JP6980636B2 - Evaluation method and evaluation device - Google Patents

Description

The present invention relates to a technique for evaluating the shape of a spiral groove formed on a surface of a measurement target.

For example, the surface of a heavy and long metal round bar having a length of 1 m and a diameter of 30 cm or more is machined with a cutting machine to form a spiral groove on the surface of the metal round bar, and a screw, a propeller, a drill, etc. Manufacture of workpieces is carried out. In such a work piece, the shape of the groove is evaluated in order to prevent the production of defective products. For example, in the case of a workpiece having a male-female structure in which the workpiece is fitted to the workpiece on the receiving side, the workpiece is lifted from the cutting machine by a crane, fitted to the workpiece on the receiving side, and is fitted with a feeler gauge. The shape of the work piece is evaluated by manually measuring the gaps at dozens of places. Then, as a result of evaluating the shape, if there is a problem, the workpiece is lifted again by the crane, installed in the cutting machine, and the problem portion is machined. The above process is repeated to finally produce a workpiece having a groove shape satisfying the standard. As described above, in the conventional evaluation method, there is a problem that it takes a lot of work days because it is necessary to transfer the workpiece from the cutting machine using a crane. Therefore, a new evaluation method for solving this problem is desired.

Against this background, Patent Document 1 discloses a technique for measuring the shape of a measurement object having a spiral groove formed on the surface with high resolution and in a short time. Specifically, in Patent Document 1, the cross-sectional shape of the groove of the measurement object that moves in parallel with the central axis while rotating around the central axis of the measurement object is measured by the measuring unit in a non-contact manner, and the entire area of the groove is measured. The technique for acquiring the measurement data of the shape of the above is disclosed.

Further, Patent Document 2 discloses a three-dimensional measurement method for accurately specifying a corrected portion with respect to a design value in a measurement object having an uneven surface such as a spherical lens.

Japanese Unexamined Patent Publication No. 2015-148592 Japanese Unexamined Patent Publication No. 2002-122423

However, in the methods of Patent Documents 1 and 2, since the positional relationship between the measuring unit and the measuring object is not considered at all, there is a problem that the processing accuracy of the shape of the measuring object cannot be evaluated correctly.

An object of the present invention is to provide an evaluation method and an evaluation device for accurately evaluating the shape of a spiral groove in a measurement target having a spiral groove formed on the surface.

The first aspect of the present invention is
An evaluation method for evaluating the shape of a target groove, which is a groove of an evaluation target spirally formed around the central axis on the surface of a measurement target having a columnar rod axis concentric with the central axis.
The shape of the reference groove formed on the surface of the reference object by a measuring unit capable of measuring the shape of the object in a non-contact manner and having the same groove shape as the target groove is measured at the first measurement position, and the lowest position of the reference groove is measured. The first positioning step of obtaining the first deviation amount between the groove bottom line, which is a line connecting the two, and the center of the field of view of the measurement unit, and positioning the measurement unit at the first reference position where the first deviation amount becomes zero.
A reference groove measuring step for measuring the shape of the reference groove by the measuring unit positioned at the first reference position, and a reference groove measuring step.
The shaft shape of the rod shaft is measured by the measuring unit at the second measuring position, and the measuring unit is placed at the second reference position where the amount of deviation between the center of the visual field of the measuring unit and the top position of the rod shaft becomes zero. The second positioning step for positioning and
The measuring unit is moved from the second reference position along the central axis to measure the shape of the target groove at a plurality of measurement positions by the measuring unit, and the difference from the shape of the reference groove is minimized. A third positioning step of obtaining a third reference position, which is a position, and positioning the measuring unit at the third reference position,
A target groove measuring step for measuring the shape of the target groove by the measuring unit positioned at the third reference position, and a target groove measuring step.
An evaluation step for evaluating the shape of the target groove based on the difference between the shape of the target groove measured in the target groove measurement step and the shape of the reference groove measured in the reference groove measurement step, and an evaluation step for evaluating the shape of the target groove.
It is equipped with.

The second aspect of the present invention is
An evaluation device that evaluates the shape of a target groove, which is a groove of an evaluation target spirally formed around the central axis on the surface of a measurement target having a columnar rod axis concentric with the central axis.
A measuring unit that can measure the shape of an object in a non-contact manner,
A reference object having a reference groove having the same groove shape as the target groove formed on the surface thereof,
The shape of the reference groove is measured by the measuring unit positioned at the first measurement position, and the first deviation amount between the groove bottom line, which is a line connecting the lowest positions of the reference groove, and the center of the field of view of the measuring unit is determined. A reference groove processing unit for measuring the shape of the reference groove by the measuring unit in a state where the measuring unit is positioned at a first reference position where the first deviation amount becomes zero.
The shaft shape of the rod shaft is measured by the measuring unit at the second measuring position, and the measuring unit is placed at the second reference position where the amount of deviation between the center of the field of view of the measuring unit and the top position of the rod shaft becomes zero. The rod shaft processing unit for positioning and
The measuring unit is moved from the second reference position along the central axis to measure the shape of the target groove at a plurality of measurement positions by the measuring unit, and the difference from the shape of the reference groove is minimized. A target groove processing unit that measures the shape of the target groove by the measurement unit in a state where the measurement unit is positioned at the third reference position after obtaining a third reference position, which is a position.
An evaluation processing unit that evaluates the shape of the target groove based on the difference between the shape of the target groove measured by the target groove processing unit and the shape of the reference groove measured by the reference groove processing unit.
It is equipped with.

In the first aspect and the second aspect, the shape of the reference groove is measured by the measuring unit to obtain the first deviation amount between the center of the visual field of the measuring unit and the groove bottom line of the reference groove, and the first deviation amount becomes zero. With the measuring unit positioned at the first reference position, the shape of the reference groove is measured by the measuring unit. Therefore, even if the position of the reference object is deviated or the position of the measuring portion with respect to the reference object is deviated, the shape of the reference groove can be measured with high accuracy. Further, the shaft shape of the rod shaft is measured by the measuring unit, and the measuring unit is positioned at the second reference position where the amount of deviation between the center of the visual field of the measuring unit and the top position of the rod shaft becomes zero. Since the rod axis has a cylindrical shape, the center of the visual field of the measuring unit coincides with the central axis of the measurement target at the second reference position. Therefore, the shape of the target groove can be measured with high accuracy while the center of the visual field of the measurement unit coincides with the central axis of the measurement target. As a result, the shape of the target groove is evaluated based on the difference between the shape of the target groove measured with high accuracy and the shape of the reference groove measured with high accuracy, so that the shape of the target groove can be evaluated with high accuracy. ..

In the first aspect, for example,
In the first positioning step, the measuring unit is moved in a predetermined direction, the shape of the reference groove is measured by the measuring unit at a plurality of measuring positions including the first measuring position, and the first deviation is measured for each measurement. Each amount is obtained, a first deviation approximate straight line that approximates the relationship between each of the first deviation amounts and the plurality of measurement positions is obtained, and the position of the first deviation approximate straight line at which the first deviation amount becomes zero is obtained. It may be obtained as the first reference position.

According to this aspect, even if there is an error in the obtained first deviation amount, a first deviation approximate straight line that approximates the relationship between each first deviation amount and a plurality of measurement positions is obtained, and the first deviation is obtained. Since the position of the first deviation approximate straight line where the amount becomes zero is obtained as the first reference position, the first reference position can be obtained with high accuracy.

In the first aspect, for example,
The first positioning step is performed from the first measurement position based on the angle formed by the moving direction from the first measurement position to the first reference position and the direction in which the groove bottom line extends, and the first deviation amount. The first correction movement amount, which is the movement amount to the first reference position, may be obtained, the measurement unit may be moved by the first correction movement amount, and the measurement unit may be positioned at the first reference position.

According to this aspect, the measuring unit can be easily positioned at the first reference position only by measuring the shape of the reference groove at the first measurement position with the measuring unit.

In the first aspect, for example,
In the second positioning step, the measuring unit is moved in a predetermined direction, and axis measurement values representing the shaft shape of the rod shaft are measured by the measuring unit at a plurality of measurement positions including the second measurement position, and measured. In each case, the axis measurement value is inverted left and right with respect to the center of the field of view of the measurement unit to obtain an inversion measurement value, a difference value between the axis measurement value and the inversion measurement value is obtained, and the difference value and the plurality of are obtained. The difference approximation straight line that approximates the relationship with the measurement position is obtained, the inclination of the difference approximation straight line is obtained, the inclination approximation straight line that approximates the relationship between the inclination and the plurality of measurement positions is obtained, and the inclination becomes zero. The position of the inclination approximate straight line may be obtained as the second reference position.

In this embodiment, since the rod axis has a cylindrical shape, the axis measurement value and the inversion measurement value are bilaterally symmetric. Therefore, at the second reference position, the slope of the difference approximate straight line becomes zero. Therefore, according to this aspect, the second reference position can be obtained with high accuracy.

In the first aspect, for example,
In the second positioning step, the measuring unit is moved in a predetermined direction, the shaft shape of the rod shaft is measured by the measuring unit at a plurality of measuring positions including the second measuring position, and the measuring unit is measured for each measurement. The second deviation amount between the center of the field of view and the top position of the rod axis is obtained, and the second deviation approximate straight line that approximates the relationship between the second deviation amount and the plurality of measurement positions is obtained. The position of the second deviation approximate straight line at which the deviation amount becomes zero may be obtained as the second reference position.

According to this aspect, even if there is an error in the obtained second deviation amount, a second deviation approximate straight line that approximates the relationship between each second deviation amount and the plurality of measurement positions is obtained, and the second deviation is obtained. Since the position of the second deviation approximate straight line where the amount becomes zero is obtained as the second reference position, the second reference position can be obtained with high accuracy.

In the first aspect, for example,
In the second positioning step, the second deviation amount between the center of the field of view of the measuring unit and the top position of the rod axis is obtained, and the angle formed by the direction in which the second deviation amount extends and the direction in which the central axis extends is determined. Based on the second deviation amount, the second correction movement amount, which is the movement amount from the second measurement position to the second reference position, is obtained, and the measurement unit is moved by the second correction movement amount to obtain the second correction movement amount. 2 The measuring unit may be positioned at a reference position.

According to this aspect, the measuring unit can be easily positioned at the second reference position only by measuring the shaft shape of the rod shaft with the measuring unit at the second measuring position.

According to the present invention, the shape of the target groove is evaluated based on the difference between the shape of the target groove measured with high accuracy and the shape of the reference groove measured with high accuracy, so that the shape of the target groove is evaluated with high accuracy. be able to.

It is a block diagram which shows schematic the electric composition example of the evaluation apparatus in this embodiment. It is a figure which shows schematically the evaluation apparatus which evaluates a screw rotor. It is a figure which shows the appearance of the standard thing. It is a figure which shows schematicly the standard thing mounted on the rotor shaft of a screw rotor. It is a plan view which looked at the reference object from above. It is a top view which saw the rotor shaft of a screw rotor from above. It is a figure which shows roughly one part of a target groove and a rotor shaft. It is a figure explaining the difference value calculated by the groove shape measurement process of a target groove. It is a figure which shows an example of the approximate straight line of an inclination. It is a flowchart which shows schematic operation of the evaluation apparatus of this embodiment. It is a flowchart which shows schematic operation of the evaluation apparatus of this embodiment. It is a flowchart which shows schematic operation of the evaluation apparatus of this embodiment. It is a figure which shows the reference object and the groove shape measured value roughly. It is a figure which shows an example of the approximate straight line of the deviation amount. FIG. 3 is a flowchart schematically showing different procedures for measuring the groove shape of the reference groove shown in FIG. 10. It is a figure which shows the rotor shaft and the shaft shape measured value roughly. It is a figure which shows an example of the approximate straight line of the deviation amount. FIG. 11 is a flowchart schematically showing different procedures for measuring the shaft shape of the rotor shaft shown in FIG. 11. It is a figure which shows the rotor shaft and the shaft shape measured value roughly. It is a figure which shows an example of the approximate straight line of an inclination. FIG. 11 is a flowchart schematically showing a further different procedure of the shaft shape measuring operation of the rotor shaft shown in FIG. 11. It is a figure explaining the effect of each embodiment. It is a figure explaining the problem when each embodiment is not used.

(Embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, the same reference numerals are used for the same components, and detailed description thereof will be omitted as appropriate.

FIG. 1 is a block diagram schematically showing an example of an electrical configuration of the evaluation device 100 in the present embodiment. FIG. 2 is a diagram schematically showing an evaluation device 100 for evaluating a screw rotor 300. FIG. 3 is a diagram schematically showing the appearance of the reference object 400. FIG. 4 is a diagram schematically showing a reference object 400 mounted on the rotor shaft 320 of the screw rotor 300.

As shown in FIG. 1, the evaluation device 100 includes a display 10, an operation unit 15, a measurement unit 20, a drive unit 25, and a control circuit 30. The measuring unit 20 includes a light source 21 and a camera 22. The drive unit 25 includes a rotary drive unit 26 and a mobile drive unit 27. The control circuit 30 includes a memory 35, a central processing unit (CPU) 40, and peripheral circuits (not shown).

The display 10 includes, for example, a liquid crystal display panel. The display 10 is controlled by the CPU 40 and displays, for example, an evaluation result. The display 10 may display a groove shape measured value (FIG. 5 or the like), a shaft shape measured value (FIG. 6), or the like, which will be described later. The display 10 is not limited to the liquid crystal display panel. The display 10 may include other panels such as an organic EL (electroluminescence) panel.

The operation unit 15 includes, for example, a mouse or a keyboard. When operated by the user, the operation unit 15 outputs an operation signal indicating the operation content (for example, an instruction to start measurement) to the CPU 40. When the display 10 is a touch panel display, the touch panel display may also serve as the operation unit 15 instead of the mouse or keyboard.

The memory 35 is composed of, for example, a semiconductor memory or the like. The memory 35 includes, for example, a read-only memory (ROM), a random access memory (RAM), an electrically erasable and rewritable ROM (EEPROM), and the like. For example, the ROM of the memory 35 stores the control program of the present embodiment for operating the CPU 40.

By operating according to the control program of the present embodiment stored in the memory 35, the CPU 40 serves as a measurement control unit 41, a reference groove processing unit 42, a rotor shaft processing unit 43, a target groove processing unit 44, and an evaluation processing unit 45. Function. The functions of the measurement control unit 41, the reference groove processing unit 42, the rotor shaft processing unit 43, the target groove processing unit 44, and the evaluation processing unit 45 will be described later.

As shown in FIG. 2, the evaluation device 100 includes a pedestal portion 110, a pair of holding portions 120, a measuring portion 20, a support portion 140, and a top plate portion 150. The evaluation device 100 evaluates the shape of the target groove 302, which is a groove spirally formed around the central axis CZ on the surface of the screw rotor 300 (corresponding to an example of the measurement target). The screw rotor 300 has a rotor shaft 320 (corresponding to an example of a rod shaft) concentric with the central shaft CZ. The rotor shaft 320 is a cylindrical member extending along the central shaft CZ. Although not shown in the drawings of the present specification, the target groove 302 is formed in a spiral shape while being twisted around the central axis CZ. The groove evaluated by the evaluation device 100 is not limited to that formed in the screw rotor 300, and may be, for example, a groove formed in a drill bit of a cutting tool or the like.

In this embodiment, as shown in FIG. 2, the X, Y, and Z directions are set. The Z direction is set to the left-right direction in FIG. 2, the + Z direction is set to the right direction in FIG. 2, and the −Z direction is set to the left direction in FIG. The Y direction is set in the vertical direction of FIG. 2, the + Y direction is set upward in FIG. 2, and the −Y direction is set downward in FIG. In FIG. 2, the X direction is set to the normal direction of the paper surface, the −X direction is set to the depth direction of the paper surface of FIG. 2, and the + X direction is set to the front side of the paper surface of FIG.

The pedestal portion 110 has a flat plate shape and is fixed to, for example, the floor of a factory where the evaluation device 100 is installed. The pair of holding portions 120 are provided at both left and right ends of FIG. 2 of the pedestal portion 110, respectively. Each of the pair of holding portions 120 has, for example, a chuck, and holds both ends of the rotor shaft 320 of the screw rotor 300, respectively. The screw rotor 300 is held by a pair of holding portions 120 so that the central axis CZ of the screw rotor 300 is parallel to the Z direction, and is arranged on the pedestal portion 110.

The top plate portion 150 has a flat plate shape and is installed above the pedestal portion 110. A support portion 140 is attached to the lower surface of the top plate portion 150. The support unit 140 integrally and rotatably supports the light source 21 and the camera 22 included in the measurement unit 20. The rotary drive unit 26 includes, for example, a stepping motor. The measurement control unit 41 controls the rotation drive unit 26 to integrally rotate the light source 21 and the camera 22 with respect to the support unit 140.

The support portion 140 is installed on the top plate portion 150 so as to be movable in the Z direction and the X direction. For example, the top plate portion 150 is provided with one guide groove (not shown) parallel to the Z direction directly above the central axis CZ of the screw rotor 300, and is provided at a plurality of predetermined positions in the Z direction. A plurality of guide grooves (not shown) are provided in parallel with the X direction, and a roller (not shown) that fits into these guide grooves is provided on the upper surface of the support portion 140. The support portion 140 can be moved in the Z direction and the X direction with respect to the top plate portion 150 by being guided by the rollers in these guide grooves. The mobile drive unit 27 includes, for example, a stepping motor. The measurement control unit 41 controls the movement drive unit 27 to move the support unit 140 in the Z direction and the X direction with respect to the top plate unit 150.

The measuring unit 20 measures the three-dimensional shape of an object in a non-contact manner by a light cutting method. The light source 21 and the camera 22 of the measuring unit 20 are electrically connected to the control circuit 30. The light source 21 is controlled by the measurement control unit 41 and emits the slit light directly downward. The optical cutting method using slit light can improve the measurement efficiency because three-dimensional coordinates for one slit (light cutting line) can be obtained at a time. The slit light may be obtained, for example, by forming the spot light into a slit shape with a cylindrical lens. Alternatively, the slit light may be obtained by one-dimensionally scanning the spot light.

The camera 22 captures the reflected light in which the slit light is reflected by the object. The camera 22 outputs the captured data to the control circuit 30. The relative positional relationship between the light source 21 and the camera 22, for example, the distance between the light source 21 and the camera 22, the angle between the optical axis of the light source 21 and the optical axis of the camera 22, and the like are predetermined in the memory 35. It is stored in. The measurement control unit 41 uses the position coordinates of the reflected light image of the slit light captured by the camera 22, the relative positional relationship between the light source 21 and the camera 22, and the like, and uses the principle of the triangular survey method to make the object three-dimensional. Measure the shape.

As shown in FIG. 2, the reference object 400 is mounted on the rotor shaft 320 of the screw rotor 300. As shown in FIG. 3, the reference object 400 includes an upper half portion 404 having a reference groove 402 formed on the upper surface, a lower half portion 408 connected to the upper half portion 404 and having a recess 406 formed on the lower surface, and a lower portion. Includes legs 410,412, which are connected to half 408. The recess 406 is formed in a semicircular shape in the Z direction, and is formed so as to fit into the rotor shaft 320 of the screw rotor 300 as shown in FIG. As shown in FIG. 4, the reference object 400 is supported on the pedestal portion 110 by the legs 410 and 412 in a state where the recess 406 is fitted to the rotor shaft 320 of the screw rotor 300.

The reference groove 402 is a groove for evaluating the target groove 302 of the screw rotor 300. Therefore, the reference material 400 is made of the same material as the screw rotor 300. The reference groove 402 is not spiral, but is formed linearly in a direction orthogonal to both the width direction D1 (described later in FIG. 5) and the depth direction D2 of the reference groove 402. In other words, in this orthogonal direction, the reference groove 402 has the same shape and dimensions. Further, in the reference groove 402 of the reference object 400, when the recess 406 is fitted to the rotor shaft 320, the extension direction of the reference groove 402 is parallel to the extension direction L21 (FIG. 2) of the target groove 302. , Is formed. If the shape, size, extension direction, etc. of the target groove 302 of the screw rotor 300 are different, a different reference object 400 is used. That is, the reference material 400 is prepared for each model number or specification of the screw rotor 300.

FIG. 5 is a plan view of the reference object 400 as viewed from above. That is, FIG. 5 is a view of the reference object 400 mounted on the rotor shaft 320 of the screw rotor 300 (FIG. 2) as viewed from the + Y direction to the −Y direction. In FIG. 5, the X-axis is set at the center of the field of view in the Z direction of the measuring unit 20 (camera 22) arranged at the position Z6. The shape measurement of the reference groove 402 will be described with reference to FIGS. 1 and 5.

In FIG. 5, the groove bottom line CB1 is a line connecting the lowest positions of the reference groove 402. That is, the groove bottom line CB1 is orthogonal to the width direction D1 of the reference groove 402. When the reference object 400 to be used is determined, the user inputs in advance the extending direction of the groove bottom line CB1 (or the width direction D1 of the reference groove 402) using the operation unit 15 (FIG. 1). The measurement control unit 41 (FIG. 1) controls the rotation drive unit 26 to rotate the measurement unit 20 so that the slit light emitted from the light source 21 is orthogonal to the input groove bottom line CB1. Therefore, in FIG. 5, the slit lights SLa and SL6 are orthogonal to the groove bottom line CB1. Further, the extending direction of the groove bottom line CB1 determines the angle θ between the extending direction of the groove bottom line CB1 and the X direction in a plan view seen from above the paper surface (that is, the + Y direction) in FIG. Therefore, the measurement control unit 41 (FIG. 1) calculates the angle θ based on the input direction of the groove bottom line CB1 and stores it in the memory 35 in advance.

Here, using the reference groove 402 as an example, data representing the shape of an object measured by the light source 21 of the measuring unit 20 and the camera 22 will be described. For example, the data representing the shape of the reference groove 402 measured by the slit light SLa emitted from the light source 21 is incident with the slit light SLa when a certain position in the Y direction is set as the reference height (or reference depth). Represents the height (or depth) of each of the multiple sampling points at a position.

The measurement control unit 41 acquires an image taken by the camera 22, and the coordinates of the optical cut line (for example, the reflected light of the slit light SLa) appearing in the image, the optical axis of the camera 22 and the optical axis of the light source 21 form each other. The height data of each sampling point is calculated by the principle of the triangular survey method based on the angle, the distance between the light source 21 and the camera 22 and the like. As the coordinates of the optical cutting line, for example, when the optical cutting line extends in the horizontal direction of the image, the coordinates in the vertical direction are adopted. In this case, the measurement control unit 41 sets the attention line parallel to the vertical direction with respect to the image in which the optical cut line appears, and performs the process of searching for the coordinates where the peak of the pixel value appears in the attention line horizontally. By repeating while shifting in the direction, the coordinates of the optical cut line at each sampling point are specified.

The measurement control unit 41 controls the movement drive unit 27 to move the measurement unit 20 in the Z direction and position it at the position Z6. The measurement control unit 41 controls the movement drive unit 27 to move the measurement unit 20 in the X direction and position it at an arbitrary position Xa (corresponding to an example of the first measurement position) on the reference object 400. The measurement control unit 41 controls the measurement unit 20 to emit the slit light SLa from the light source 21 and measures the height data of the reference groove 402 by the camera 22.

The height data measured by the measurement control unit 41 based on the image pickup data of the camera 22 is discrete data at each sampling point. Therefore, the reference groove processing unit 42 obtains a curve such as the groove shape measurement value 500 (FIG. 5) from the discrete data by regression analysis such as polynomial fitting using the least squares method. The horizontal axis (position) of the groove shape measurement value 500 shown in FIG. 5 represents the distance from the visual field center VC1 in the slit light SLa. The reference groove processing unit 42 calculates the deviation amount L1 (corresponding to an example of the first deviation amount) between the visual field center VC1 and the groove bottom line CB1 based on the groove shape measurement value 500.

The reference groove processing unit 42 uses the calculated deviation amount L1 and the angle θ between the groove bottom line CB1 and the X axis stored in advance in the memory 35 to form the center of the visual field and the groove bottom line CB1 from the position Xa. The corrected movement amount M1 (corresponding to an example of the first corrected movement amount) up to the matching position X1 (corresponding to an example of the first reference position) is
M1 = L1 / sinθ
Calculated by. The angle θ can also be said to be the angle formed by the moving direction from the position Xa to the position X1 and the direction in which the groove bottom line CB1 extends.

The measurement control unit 41 controls the movement drive unit 27 to move the measurement unit 20 in the X direction by the correction movement amount M1 to position the measurement unit 20 at the position X1. The measurement control unit 41 controls the measurement unit 20 to emit the slit light SL6 from the light source 21, and acquires the height data of the reference groove 402 by the camera 22. The reference groove processing unit 42 obtains a curve as shown in the groove shape measurement value 505 (FIG. 5) from the height data acquired by the measurement control unit 41 by regression analysis such as polynomial fitting. The reference groove processing unit 42 stores the obtained groove shape measurement value 505 in the memory 35.

FIG. 6 is a plan view of the rotor shaft 320 of the screw rotor as viewed from above. That is, FIG. 6 is a view of the rotor shaft 320 of the screw rotor viewed from the + Y direction to the −Y direction. In FIG. 6, the X-axis is set at the center of the field of view in the Z direction of the measuring unit 20 (camera 22) arranged at the position Z7. The shaft shape measurement of the rotor shaft 320 by the rotor shaft processing unit 43 will be described with reference to FIGS. 1 and 6.

The measurement control unit 41 controls the movement drive unit 27 to move the measurement unit 20 in the Z direction and position it at the position Z7. The measurement control unit 41 controls the movement drive unit 27 to move the measurement unit 20 in the X direction and position it at an arbitrary position Xb (corresponding to an example of the second measurement position) on the rotor shaft 320. The measurement control unit 41 controls the measurement unit 20 to emit the slit light SLb from the light source 21, and measures the height data of the rotor shaft 320 by the camera 22. The rotor shaft 320 has a cylindrical shape, and the surface of the cylinder is measured obliquely by the slit light SLb. Therefore, the height data has an elliptical shape. Therefore, the apex of the ellipse (that is, the top position of the rotor shaft 320) is located on the central axis CZ.

As described above, the height data measured by the measurement control unit 41 based on the image pickup data of the camera 22 is discrete data of each sampling point. Therefore, the rotor shaft processing unit 43 obtains a curve as shown in the shaft shape measurement value 510 (FIG. 6) from the discrete data by regression analysis such as polynomial fitting or ellipse fitting. The horizontal axis (position) of the shaft shape measurement value 510 shown in FIG. 6 represents the distance from the visual field center VC2 in the slit light SLb. The rotor shaft processing unit 43 calculates the deviation amount L2 (corresponding to an example of the second deviation amount) between the visual field center VC2 and the top position VT based on the shaft shape measurement value 510. The top position VT is the position of the highest height AP on the rotor shaft 320 that reflects the slit light SLb. In other words, the top position VT corresponds to the point where the slit light SLb and the central axis CZ intersect when viewed from the + Y direction.

The rotor shaft processing unit 43 uses the calculated deviation amount L2 and the angle θ stored in advance in the memory 35 to position X2 (second reference) where the top position VT and the center of the visual field coincide with each other from the position Xb. The corrected movement amount M2 (corresponding to an example of the second corrected movement amount) up to (corresponding to an example of the position),
M2 = L2 × sinθ
Calculated by. The measurement control unit 41 moves the measurement unit 20 in the X direction by the correction movement amount M2, and positions the measurement unit 20 at the position X2. In FIG. 6, the angle θ is represented as an angle formed by the central axis CZ and the slit light SLb, but as can be seen from FIGS. 5 and 6, the angle θ in FIG. 5 and the angle θ in FIG. 6 Are the same size.

FIG. 7 is a diagram schematically showing a part of one target groove 302 and a rotor shaft 320. FIG. 8 is a diagram illustrating a difference value calculated by the groove shape measurement process of the target groove 302. FIG. 9 is a diagram showing an example of an approximate straight line of inclination. The groove shape measurement of the target groove 302 by the target groove processing unit 44 will be described with reference to FIGS. 1 and 7 to 9.

The measurement control unit 41 sets a predetermined range R along the central axis CZ (that is, in the Z direction), and measures the groove shape of the target groove 302 by the measuring unit 20 at a plurality of measurement positions included in the predetermined range R. .. As a result, a plurality of groove shape measurement values can be obtained. In the example of FIG. 7, the predetermined range R is a range between the position Z5 and the position Z4 with the position Z3 as the center.

In FIG. 7, the groove bottom line CB2 is a line connecting the lowest positions of the target groove 302. The slit light SL1 passing through the point P302 is emitted from the light source 21 at the position Z1, the slit light SL3 is emitted from the light source 21 at the position Z3, the slit light SL4 is emitted from the light source 21 at the position Z4, and the slit light SL4 is emitted from the light source 21 at the position Z5. Light SL5 is emitted. The point P302 on the groove bottom line CB2 is located at the lowest point of the target groove 302 on the cut surface when the screw rotor 300 is cut on a plane parallel to the Y direction including the central axis CZ.

Here, the reason for measuring the shape of the target groove 302 at a plurality of measurement positions included in the predetermined range R will be described. As described above, the target groove 302 is formed in a spiral shape while being twisted around the central axis CZ. That is, in FIG. 7, for convenience, the groove bottom line CB2 is shown as a straight line, but in reality, the groove bottom line CB2 becomes a curved line. Therefore, only the slit light SL1 passing through the point P302 is orthogonal to the groove bottom line CB2. That is, the slit lights SL3, SL4, SL5 are not orthogonal to the groove bottom line CB2. Therefore, the shape of the target groove 302 to be measured will be different even if it is slightly deviated from the position Z1 along the central axis CZ. Therefore, when measuring the shape of the target groove 302, it is necessary to accurately position the measuring unit 20 at the position Z1.

The screw rotor 300 is designed and manufactured so that the shape and dimensions of the target groove 302 as measured by the slit light SL1 match the shape and dimensions of the reference groove 402. In other words, when the screw rotor 300 is manufactured as designed without manufacturing error, the shape and dimensions of the target groove 302 as measured by the slit light SL1 match the shape and dimensions of the reference groove 402. do.

The position Z1 can be specified based on design values such as the length of the rotor shaft 320 and the spiral shape of the target groove 302 when the screw rotor 300 is held by the holding portion 120 and arranged on the pedestal portion 110. Is. However, a position error when arranging the screw rotor 300 on the pedestal portion 110 inevitably occurs. Therefore, there is a possibility that the shape of the target groove 302 is measured by the slit light SL3 in a state where the measuring unit 20 is positioned at the position Z3 specified based on the design value. As shown in FIG. 7, this position Z3 deviates from the position Z1. In that case, the shape of the target groove 302 for comparison with the reference groove 402 cannot be accurately measured.

Therefore, the user sets a predetermined range R along the central axis CZ centering on the position specified by the design value of the screw rotor 300 (position Z3 in this embodiment). The user determines the predetermined range R in advance so that the position Z1 is always included in the predetermined range R in consideration of the above error. The user uses the operation unit 15 to store the size of the determined predetermined range R in the memory 35 in advance. In the present embodiment, as shown in FIG. 7, the predetermined range R is a position Z4 separated by δ [mm] in the −Z direction and a position Z5 separated by δ [mm] in the + Z direction with respect to the position Z3. It is determined within the range specified by.

The measurement control unit 41 controls the movement drive unit 27 to move the measurement unit 20 positioned at the position X2 in the X direction in the Z direction (that is, along the central axis CZ), and the positions Z3, Z4, Z5. The height data of the target groove 302 is measured by the measuring unit 20 at n (n is an integer of 3 or more) measurement positions in a predetermined range R including. The target groove processing unit 44 generates n groove shape measurement values of the target groove 302 from the height data of the target groove 302 by regression analysis such as polynomial fitting. The target groove processing unit 44 has n of each of the n groove shape measurement values of the target groove 302 and the groove shape measurement value 505 (FIG. 5) of the reference groove 402 measured by the slit light SL6 (FIG. 5). The difference values DD-1 to DD-n of are calculated.

In the figure showing the difference value in FIG. 8, the line shown in black represents the difference value DD-1, DD-m, DD-n, and the straight line shown in gray is the difference value DD-1, DD-m, Represents an approximate straight line of DD-n. Further, the figure showing the groove shape measurement value SD-1 by the slit light SL1, the groove shape measurement value SD-m by the slit light SL3, the groove shape measurement value SDn by the slit light SL5, and the groove shape measurement value SD2 by the slit light SL6. In, the horizontal axis represents the position on the cross section along each slit light (that is, along the width direction D1 of the reference groove 402), and the vertical axis represents the depth of the groove shape. Since the vertical axis represents the depth of the groove shape, the groove shape measurement value SD2 by the slit light SL6 represents the same as the groove shape measurement value 505 (FIG. 5) of the reference groove 402, but the curve. Is upside down.

The target groove processing unit 44 calculates approximately straight lines of n difference values DD-1 to DD-n, respectively. The target groove processing unit 44 calculates the slopes of the calculated n approximate straight lines, respectively. As described above, the slit light SL4 emitted from the light source 21 at the position Z4, the slit light SL3 emitted from the light source 21 at the position Z3, and the slit light SL5 emitted from the light source 21 at the position Z5 are the groove bottom lines CB2, respectively. Not orthogonal to. Therefore, the shape and dimensions of the target groove 302 measured at the positions Z4, Z3, and Z5 do not match the shape and dimensions of the reference groove 402. Therefore, the slopes of the approximate straight lines of the difference value DD-1, the difference value DD-m, and the difference value DD-n do not become zero.

As shown in FIG. 9, for example, the target groove processing unit 44 calculates a slope approximation straight line representing the relationship between n measurement positions and n slopes by regression analysis such as polynomial fitting. In FIG. 9, the horizontal axis represents the position in the Z direction, and the vertical axis represents the inclination. The black circles (11 in the example of FIG. 9) shown in FIG. 9 represent the calculated values of the slopes calculated corresponding to each of the n measurement positions.

The target groove processing unit 44 determines whether or not the calculated values of n slopes are outliers with respect to the calculated approximate straight line. For the determination of outliers, a method for statistically determining outliers such as studentized residuals and standard deviation of residuals is used. When the calculated value of any of the slopes is determined to be an outlier, the target groove processing unit 44 excludes the calculated value of the slope determined to be an outlier and recalculates the approximate straight line of the slope. For example, in FIG. 9, when the calculated slope value DV1 is determined to be an outlier, the target groove processing unit 44 excludes the calculated slope value DV1 and recalculates the slope approximate straight line. The target groove processing unit 44 repeats this until the calculated value of the slope determined to be an outlier disappears. The target groove processing unit 44 calculates the position Z1 in the Z direction where the slope becomes zero in the calculated slope approximation straight line.

The measurement control unit 41 controls the movement drive unit 27 to position the measurement unit 20 at the position Z1 calculated by the target groove processing unit 44. The measurement control unit 41 emits the slit light SL1 from the light source 21 at this position Z1, images the reflected light of the slit light SL1 by the camera 22, and measures the height data of the target groove 302. The target groove processing unit 44 generates a groove shape measurement value from the measured height data by regression analysis such as polynomial fitting.

The evaluation processing unit 45 evaluates the shape of the target groove 302 based on the difference between the groove shape measurement value of the target groove 302 obtained by this measurement and the groove shape measurement value 505 (FIG. 5) of the reference groove 402. .. As described above, the screw rotor 300 is designed and manufactured so that the shape and dimensions of the target groove 302 measured by the slit light SL1 match the shape and dimensions of the reference groove 402 of the reference object 400. Therefore, the groove shape measurement value of the target groove 302 should ideally match the groove shape measurement value 505 of the reference groove 402. However, in reality, the two do not match due to a machining error of the target groove 302 or the like. Therefore, the evaluation processing unit 45 evaluates the shape of the target groove 302 based on the difference between the groove shape measurement value of the target groove 302 and the groove shape measurement value 505 (FIG. 5) of the reference groove 402.

For example, the evaluation processing unit 45 obtains a difference value between the heights corresponding to the sampling points in the groove shape measurement value of the target groove 302 and the groove shape measurement value 505 of the reference groove 402, and the statistical value of the difference value. (For example, the average value) is calculated. As a result, the evaluation processing unit 45 calculates the evaluation value of the difference value between the groove shape measurement value of the target groove 302 and the groove shape measurement value 505 of the reference groove 402. If the evaluation value is equal to or less than a predetermined evaluation reference value, the evaluation processing unit 45 determines that the groove shape of the target groove 302 is normal, and if the evaluation value exceeds the evaluation reference value, the groove shape of the target groove 302 is changed. Judged as abnormal.

The measurement control unit 41 and the target groove processing unit 44 may generate the groove shape measurement value of the target groove 302 at a plurality of positions. For example, in each of the four target grooves 302 shown in FIG. 2, the position Z1 may be obtained and the groove shape measured values of the four target grooves 302 may be generated. In this case, the evaluation processing unit 45 may obtain an evaluation value for the groove shape measured value of the target groove 302 at each of the plurality of positions. The evaluation processing unit 45 may determine that the shape of the target groove 302 is normal, for example, if all the evaluation values are equal to or less than the evaluation reference value.

10 to 12 are flowcharts schematically showing the operation of the evaluation device 100 of the present embodiment. FIG. 10 shows the groove shape measuring operation of the reference groove 402, FIG. 11 shows the shaft shape measuring operation of the rotor shaft 320, and FIG. 12 shows the groove shape measuring operation of the target groove 302. The operation of FIGS. 10 to 12 is started when the user instructs the start of measurement using, for example, the operation unit 15.

In step S1000 of FIG. 10, the measurement control unit 41 controls the movement drive unit 27 to move the measurement unit 20 in the Z direction and positions it at the position Z6 (FIG. 5) above the reference object 400. In step S1005, the measurement control unit 41 controls the movement drive unit 27 to move the measurement unit 20 in the X direction, positions the measurement unit 20 at the position Xa (FIG. 5) above the reference groove 402, and is positioned by the measurement unit 20. The height data of the reference groove 402 is measured. In step S1010, the reference groove processing unit 42 generates a groove shape measurement value 500 (FIG. 5) of the reference groove 402 based on the measured height data. In step S1015, the reference groove processing unit 42 calculates the deviation amount L1 between the visual field center VC1 and the groove bottom line CB1. In step S1020, the reference groove processing unit 42 calculates the correction movement amount M1 from the position Xa to the position X1 where the center of the visual field and the groove bottom line CB1 coincide.

In step S1025, the reference groove processing unit 42 moves the measurement unit 20 in the X direction by the correction movement amount M1, positions the measurement unit 20 at the position X1, and measures the height data of the reference groove 402 by the measurement unit 20. do. In step S1030, the reference groove processing unit 42 generates a groove shape measurement value 505 (FIG. 5) of the reference groove 402 based on the measured height data, and stores the generated groove shape measurement value 505 in the memory 35. do. In the present embodiment, steps S1000 to S1025 correspond to an example of the first positioning step, and steps S1025 to S1030 correspond to an example of the reference groove measurement step.

In step S1100 of FIG. 11, the measurement control unit 41 controls the movement drive unit 27 to move the measurement unit 20 in the Z direction and positions the measurement unit 20 at the position Z7 on the rotor shaft 320. In step S1105, the measurement control unit 41 controls the movement drive unit 27 to move the measurement unit 20 in the X direction, positions the measurement unit 20 at the position Xb (FIG. 6) on the rotor shaft 320, and is positioned by the measurement unit 20. The height data of the rotor shaft 320 is measured. In step S1110, the rotor shaft processing unit 43 generates a shaft shape measurement value 510 (FIG. 6) based on the measured height data, and stores the generated shaft shape measurement value 510 in the memory 35.

In step S1115, the rotor shaft processing unit 43 calculates the deviation amount L2 between the visual field center VC2 and the top position VT based on the shaft shape measurement value 510. In step S1120, the rotor shaft processing unit 43 calculates the corrected movement amount M2 from the position Xb to the position X2 where the top position VT (FIG. 6) and the center of the visual field (X axis) coincide. In step S1125, the rotor shaft processing unit 43 moves the measuring unit 20 in the X direction by the correction movement amount M2, and positions the measuring unit 20 at the position X2. In the present embodiment, steps S1100 to S1125 correspond to an example of the second positioning step.

In step S1200 of FIG. 12, the measurement control unit 41 controls the movement drive unit 27 to move the measurement unit 20 in the Z direction, for example, n in a predetermined range R from the position Z5 (FIG. 7) to the position Z4. The height data of the target groove 302 is measured by the measuring unit 20 at each measurement position. In step S1205, the target groove processing unit 44 generates n groove shape measurement values of the target groove 302 from the height data of the target groove 302 by regression analysis such as polynomial fitting. In step S1210, the target groove processing unit 44 calculates n difference values between each of the n groove shape measurement values of the target groove 302 and the groove shape measurement value 505 of the reference groove 402.

In step S1215, the target groove processing unit 44 calculates approximate straight lines of the difference values at the n measurement positions. In step S1220, the target groove processing unit 44 calculates the slopes of the calculated n approximate straight lines. In step S1225, the target groove processing unit 44 calculates an approximate straight line of inclination. In step S1230, the target groove processing unit 44 determines whether or not the calculated values of n slopes are outliers with respect to the calculated approximate straight line. If the calculated value of any of the slopes is determined to be an outlier (YES in step S1230), the process proceeds to step S1235. On the other hand, if it is determined that the calculated values of all the slopes are not outliers (NO in step S1230), the process proceeds to step S1240. In step S1235, the target groove processing unit 44 excludes the calculated value of the slope determined to be an outlier, and the process returns to step S1225.

In step S1240, the target groove processing unit 44 calculates the position Z1 in the Z direction where the slope becomes zero in the calculated slope approximate straight line. In step S1245, the measurement control unit 41 controls the movement drive unit 27 to position the measurement unit 20 at the position Z1 and measure the height data of the target groove 302. In step S1250, the target groove processing unit 44 generates a groove shape measured value of the target groove 302 from the measured height data. In step S1255, the evaluation processing unit 45 evaluates the shape of the target groove 302 based on the difference between the groove shape measurement value of the target groove 302 and the groove shape measurement value 505 (FIG. 5) of the reference groove 402. The operation of FIG. 12 ends. In the present embodiment, steps S1200 to S1245 correspond to an example of a third positioning step, steps S1245 to S1250 correspond to an example of a target groove measurement step, and step S1255 corresponds to an example of an evaluation step.

(Deformation form related to groove shape measurement of reference groove 402)
FIG. 13 is a diagram schematically showing the reference object 400 and the groove shape measured values. FIG. 14 is a diagram showing an example of an approximate straight line having a deviation amount L1. FIG. 15 is a flowchart schematically showing different procedures for measuring the groove shape of the reference groove 402 shown in FIG. A modified embodiment of the shape measurement of the reference groove 402 will be described with reference to FIGS. 13-15.

In step S1000 of FIG. 15, the measurement control unit 41 controls the movement drive unit 27 to move the measurement unit 20 in the Z direction and position it at the position Z6 in the same manner as in FIG. In step S1500, the measurement control unit 41 controls the movement drive unit 27, moves the measurement unit 20 in the X direction, positions the measurement unit 20 at the initial position X0 (FIG. 13) on the reference object 400, and causes the measurement unit 20 to position the measurement unit 20 at the initial position X0 (FIG. 13). The height data of the reference groove 402 is measured. In step S1505, the reference groove processing unit 42 generates a groove shape measured value 505-0 (FIG. 13) of the reference groove 402 by regression analysis such as polynomial fitting from the measured height data. In step S1510, the reference groove processing unit 42 calculates the deviation amount L1 between the center of the visual field and the groove bottom line CB1 and stores it in the memory 35.

In step S1515, the measurement control unit 41 determines whether or not the measurement unit 20 has moved to X0 + ΔX × N. If the measuring unit 20 has not moved to X0 + ΔX × N (NO in step S1515), the process proceeds to step S1520. On the other hand, if the measuring unit 20 has moved to X0 + ΔX × N (YES in step S1515), the process proceeds to step S1525. At this time, the measurement control unit 41 may control the movement drive unit 27 to stop the measurement unit 20.

In step S1520, the measurement control unit 41 moves the measurement unit 20 by ΔX in the X direction and measures the height data of the reference groove 402 by the measurement unit 20. After that, the process returns to step S1505. When the measuring unit 20 moves to the position X0 + ΔX × N, in step S1505, the reference groove processing unit 42 generates the groove shape measured value 505-N (FIG. 13). In this way, (N + 1) groove shape measured values 505 to 505-N at (N + 1) measurement positions are generated.

In step S1525, the reference groove processing unit 42 calculates an approximate straight line L1 = aX + b (FIG. 14) with a deviation amount L1. In step S1530, the reference groove processing unit 42 determines whether or not the calculated value of the deviation amount L1 of (N + 1) pieces is an outlier with respect to the calculated approximate straight line. If any of the calculated values of the deviation amount L1 is determined to be an outlier (YES in step S1530), the process proceeds to step S1535. On the other hand, if it is determined that all the calculated values of the deviation amount L1 are not outliers (NO in step S1530), the process proceeds to step S1540.

In step S1535, the reference groove processing unit 42 excludes the calculated value of the deviation amount L1 determined to be an outlier, and the processing returns to step S1525. For example, when the calculated value DV2 of the deviation amount L1 in FIG. 14 is determined to be an outlier, the reference groove processing unit 42 excludes this calculated value DV2 (step S1535), and the approximate straight line L1 = aX + b of the deviation amount L1. (FIG. 14) is calculated (step S1525).

In step S1540, the reference groove processing unit 42 calculates the position X1 = −b / a in the X direction in which the deviation amount L1 becomes zero in the calculated approximate straight line L1 = aX + b. Subsequent steps S1025 and S1030 are the same as steps S1025 and S1030 in FIG. 10, respectively. In this embodiment, steps S1000 to S1025 in FIG. 15 correspond to an example of the first positioning step, and the approximate straight line L1 in FIG. 17 corresponds to an example of the first deviation approximate straight line.

In the method described with reference to FIGS. 5 and 10 of the above-described embodiment, the measurement error of the deviation amount L1 becomes large due to variations in the measured values and the like, and there is a possibility that the desired measurement accuracy cannot be obtained. On the other hand, in the embodiment of FIGS. 13 to 15, the measuring unit 20 is moved from the initial position X0 to X = X0 + ΔX × N at the ΔX pitch, and the groove shape measured value of the reference groove 402 is generated at each measuring position. Then, the deviation amount L1 between the groove bottom line CB1 and the center of the visual field is calculated. When these calculated values of the deviation amount L1 are plotted, as shown in FIG. 14, the deviation amount L1 is proportional to the movement amount of the measuring unit 20 in the X direction. By calculating an approximate straight line with respect to the calculated value of the deviation amount L1 and calculating the position X1 at which the deviation amount L1 becomes zero, it is possible to specify the position in the X direction where the center of the visual field and the groove bottom line CB1 coincide. The method for determining the outliers may be the same as in the above embodiment.

(Deformed form related to shaft shape measurement of rotor shaft 320)
FIG. 16 is a diagram schematically showing a rotor shaft 320 and shaft shape measured values. FIG. 17 is a diagram showing an example of an approximate straight line having a deviation amount L2. FIG. 18 is a flowchart schematically showing different procedures for measuring the shaft shape of the rotor shaft 320 shown in FIG. A modified embodiment of the shaft shape measurement of the rotor shaft 320 by the rotor shaft processing unit 43 will be described with reference to FIGS. 16 to 18.

In step S1100 of FIG. 18, the measurement control unit 41 controls the movement drive unit 27 to move the measurement unit 20 in the Z direction and position it at the position Z7 in the same manner as in FIG. In step S1800, the measurement control unit 41 controls the movement drive unit 27, moves the measurement unit 20 in the X direction, positions it at the initial position X3 (FIG. 16) on the rotor shaft 320, and causes the measurement unit 20 to position the measurement unit 20 at the initial position X3 (FIG. 16). The height data of the rotor shaft 320 is measured. In step S1805, the rotor shaft processing unit 43 generates a shaft shape measured value 510-0 (FIG. 16) of the rotor shaft 320 from the measured height data by regression analysis such as polynomial fitting. In step S1810, the rotor shaft processing unit 43 calculates the deviation amount L2 between the top position and the center of the visual field and stores it in the memory 35.

In step S1815, the measurement control unit 41 determines whether or not the measurement unit 20 has moved to X3 + ΔXk × M. If the measuring unit 20 has not moved to X3 + ΔXk × M (NO in step S1815), the process proceeds to step S1820. On the other hand, if the measuring unit 20 has moved to X3 + ΔXk × M (YES in step S1815), the process proceeds to step S1825. At this time, the measurement control unit 41 may control the movement drive unit 27 to stop the measurement unit 20.

In step S1820, the measurement control unit 41 moves the measurement unit 20 by ΔXk in the X direction and measures the height data of the rotor shaft 320 by the measurement unit 20. After that, the process returns to step S1805. When the measuring unit 20 moves to the position X3 + ΔXk × M, in step S1805, the rotor shaft processing unit 43 generates the shaft shape measured value 510-M (FIG. 16). In this way, (M + 1) shaft shape measured values 510- to 510-M at (M + 1) measurement positions are generated.

In step S1825, the rotor shaft processing unit 43 calculates an approximate straight line L2 = cX + d (FIG. 17) with a deviation amount L2 by regression analysis such as polynomial fitting. In step S1830, the rotor shaft processing unit 43 determines whether or not the calculated value of the deviation amount L2 of (M + 1) pieces is an outlier with respect to the calculated approximate straight line. When any of the calculated values of the deviation amount L2 is determined to be an outlier (YES in step S1830), the process proceeds to step S1835. On the other hand, if it is determined that all the calculated values of the deviation amount L2 are not outliers (NO in step S1830), the process proceeds to step S1840.

In step S1835, the rotor shaft processing unit 43 excludes the calculated value of the deviation amount L2 determined to be an outlier, and the processing returns to step S1825. For example, when the calculated value DV3 of the deviation amount L2 in FIG. 17 is determined to be an outlier, the rotor shaft processing unit 43 excludes this calculated value DV3 (step S1835), and the approximate straight line L2 = cX + d of the deviation amount L2. (FIG. 17) is calculated (step S1825).

In step S1840, the rotor shaft processing unit 43 calculates the position X2 = −d / c (FIG. 17) in the X direction in which the deviation amount L2 becomes zero in the calculated approximate straight line L2 = cX + d. Subsequent step S1125 is the same as step S1125 in FIG. In this embodiment, steps S1100 to S1125 in FIG. 18 correspond to an example of the second positioning step, and the approximate straight line L2 in FIG. 17 corresponds to an example of the second deviation approximate straight line.

In the method described with reference to FIGS. 6 and 11 of the above-described embodiment, the measurement error of the deviation amount L2 becomes large due to variations in the measured values and the like, and there is a possibility that the desired measurement accuracy cannot be obtained. On the other hand, in the embodiment of FIGS. 16 to 18, the measuring unit 20 is moved from the initial position X3 to X = X3 + ΔXk × M at the ΔXk pitch, and the shaft shape measured value of the rotor shaft 320 is generated at each measuring position. Then, the amount of deviation L2 between the top position and the center of the visual field is calculated. When these calculated values of the deviation amount L2 are plotted, as shown in FIG. 17, the deviation amount L2 is proportional to the movement amount of the measuring unit 20 in the X direction. By calculating an approximate straight line with respect to the calculated value of the deviation amount L2 and calculating the position X2 at which the deviation amount L2 becomes zero, the position in the X direction where the top position and the center of the visual field coincide with each other can be specified. The method for determining the outliers may be the same as in the above embodiment.

(Another deformation form related to the shaft shape measurement of the rotor shaft 320)
FIG. 19 is a diagram schematically showing a rotor shaft 320 and shaft shape measured values. FIG. 20 is a diagram showing an example of an approximate straight line of the inclination GR. FIG. 21 is a flowchart schematically showing a further different procedure of the shaft shape measuring operation of the rotor shaft 320 shown in FIG. 19 to 21 show a further modified embodiment of the shaft shape measurement of the rotor shaft 320 by the rotor shaft processing unit 43.

In step S1100 of FIG. 21, the measurement control unit 41 controls the movement drive unit 27 to move the measurement unit 20 in the Z direction and position it at the position Z7, as in FIG. In step S1800, the measurement control unit 41 controls the movement drive unit 27 to move the measurement unit 20 in the X direction and positions it at the initial position X3 (FIG. 19) on the rotor shaft 320, as in FIG. Then, the height data 515-0 (FIG. 19) of the rotor shaft 320 is measured by the measuring unit 20.

In step S2100, the rotor shaft processing unit 43 calculates left-right inverted data 520-0 (FIG. 19) in which the measured height data is inverted left-right with respect to the X-axis. In step S2105, the rotor shaft processing unit 43 subtracts the left-right inversion data from the height data to calculate the difference value. In step S2110, the rotor axis processing unit 43 calculates an approximate straight line 525-0 (FIG. 19) of the difference value by regression analysis such as polynomial fitting. In step S2115, the rotor shaft processing unit 43 determines whether or not the difference value is an outlier with respect to the calculated approximate straight line. If any of the difference values is determined to be an outlier (YES in step S2115), the process proceeds to step S2120. On the other hand, if it is determined that all the difference values are not outliers (NO in step S2115), the process proceeds to step S2125. In step S2120, the rotor shaft processing unit 43 excludes the difference value determined to be an outlier, and the processing returns to step S2110.

In step S2125, the rotor shaft processing unit 43 calculates the slope GR of the calculated approximate straight line 525-0 (FIG. 19) and stores it in the memory 35. In step S2130, the measurement control unit 41 determines whether or not the measurement unit 20 has moved to X3 + ΔXk × M. If the measuring unit 20 has not moved to X3 + ΔXk × M (NO in step S2130), the process proceeds to step S2135. On the other hand, if the measuring unit 20 has moved to X3 + ΔXk × M (YES in step S2130), the process proceeds to step S2140. At this time, the measurement control unit 41 may control the movement drive unit 27 to stop the measurement unit 20.

In step S2135, the measurement control unit 41 moves the measurement unit 20 by ΔXk in the X direction and measures the height data of the rotor shaft 320 by the measurement unit 20. After that, the process returns to step S2100. When the measuring unit 20 moves to the position X3 + ΔXk × M, in step S2135, the rotor shaft processing unit 43 measures the height data 515-M (FIG. 19) of the rotor shaft 320. In the following step S2100, the rotor shaft processing unit 43 calculates the left-right inversion data 520-M (FIG. 19). In the step S2110 following the step S2105, the rotor shaft processing unit 43 calculates an approximate straight line 525-M (FIG. 19) of the difference value. Then, in step S2125, the rotor shaft processing unit 43 calculates the slope GR of the approximate straight line 525-M (FIG. 19) of the difference value. In this way, (M + 1) approximate straight lines 525 to 525-M at (M + 1) measurement positions are calculated, and the respective slope GRs are calculated.

In step S2140, the rotor shaft processing unit 43 calculates an approximate straight line GR = pX + q (FIG. 20) of the slope GR by regression analysis such as polynomial fitting. In step S2145, the rotor shaft processing unit 43 determines whether or not the calculated values of (M + 1) slope GRs are outliers with respect to the calculated approximate straight line. If any of the calculated values of the slope GR is determined to be an outlier (YES in step S2145), the process proceeds to step S2150. On the other hand, if it is determined that all the calculated values of the slope GR are not outliers (NO in step S2145), the process proceeds to step S2155.

In step S2150, the rotor shaft processing unit 43 excludes the calculated value of the inclination GR determined to be an outlier, and the processing returns to step S2140. For example, when the calculated value DV4 of the inclination GR in FIG. 20 is determined to be an outlier, the rotor shaft processing unit 43 excludes this calculated value DV4 (step S2150), and the approximate straight line GR = pX + q of the inclination Gr (FIG. 20). 20) is calculated (step S2140).

In step S2155, the rotor shaft processing unit 43 calculates the position X2 = −q / p (FIG. 20) in the X direction at which the inclination GR becomes zero in the calculated approximate straight line GR = pX + q. Subsequent step S1125 is the same as step S1125 in FIG. In this embodiment, steps S110 to S1125 in FIG. 21 correspond to an example of the second positioning step, and the approximate straight lines 525-0,525-M in FIG. 19 correspond to an example of the difference approximate straight line, and FIG. The approximate straight line GR corresponds to an example of a slope approximate straight line.

In the method described with reference to FIGS. 6 and 11 of the above-described embodiment, the measurement error of the deviation amount L2 becomes large due to variations in the measured values and the like, and there is a possibility that the desired measurement accuracy cannot be obtained. On the other hand, in the embodiment of FIGS. 19 to 21, the measuring unit 20 is moved from the initial position X3 to X = X3 + ΔXk × M at a ΔXk pitch, and the height data of the rotor shaft 320 is measured at each measuring position. .. As described above, since the rotor shaft 320 has a cylindrical shape, the height data has an elliptical shape. Therefore, when the difference value between the height data and the left-right inverted data obtained by inverting the height data is calculated, a linear shape is obtained. For example, at the position X2 (FIG. 19) where the center of the visual field and the central axis CZ coincide, the elliptical shapes of the height data 515-C (FIG. 19) and the left-right inverted data 520-C (FIG. 19) are respectively. Since it is symmetrical, the slope of the approximate straight line 525-C (FIG. 19) of the difference value becomes zero.

By calculating the slope GR of the approximate straight line of the difference value at each measurement position and plotting the slope GR, the approximate straight line GR = pX + q as shown in FIG. 20 can be calculated. Therefore, by calculating the position X2 = −q / p at which the approximate straight line GR becomes zero, it is possible to specify the position in the X direction where the top position and the center of the visual field coincide. The method for determining the outliers may be the same as in the above embodiment.

(Effects of each of the above embodiments)
FIG. 22 is a diagram illustrating the effects of each of the above embodiments. FIG. 23 is a diagram illustrating a problem when each of the above embodiments is not used. FIG. 22 shows the reference object 400, the rotor shaft 320 of the screw rotor 300, and the target groove 302. On the other hand, FIG. 23 shows the reference object 400 and the target groove 302 of the screw rotor 300, but does not show the rotor shaft 320.

In FIG. 23, originally, the measuring unit 20 is positioned at the position Z2, and the measurement is performed by the slit light SL2 passing through the point where the groove bottom line CB1 and the central axis CZ intersect, and the groove shape of the reference groove 402 is obtained. It is hoped that the measured value 600 will be generated. Then, the measuring unit 20 moves in the Z direction, the measuring unit 20 is positioned at the position Z1, and the measurement is performed by the slit light SL1 passing through the point where the groove bottom line CB2 and the central axis CZ intersect, and the target groove 302 is performed. It is desired that the groove shape measurement value 610 of the above is generated. In this case, it is not necessary to measure the shaft shape of the rotor shaft 320.

However, in practice, when the reference object 400 is placed on the rotor shaft 320 (for example, FIG. 4) of the screw rotor 300, the reference groove 402 may be misaligned. For example, when the reference object 400 shown in FIG. 3 is manufactured, if the recess 406 is manufactured so as to be displaced in the X direction with respect to the reference groove 402, the position of the reference groove 402 is in the X direction with respect to the central axis CZ. It shifts to. Further, due to the positional deviation of the camera 22 with respect to the reference object 400, the position of the center of the field of view of the camera 22 may be displaced from the center of the groove bottom line CB1 of the reference groove 402. That is, the position of the center of the field of view of the camera 22 may shift from the position Z2 to the position Z2a.

In these cases, the measurement is performed by the slit light SLp, which is equivalent to the measurement unit 20 being positioned at the position Z2a, and the groove shape measured value 605 of the reference groove 402 is generated. Then, the measuring unit 20 moves in the Z direction, the measuring unit 20 is positioned at the position Z1a, the measurement is performed by the slit light SLq, and the groove shape measured value 615 of the target groove 302 is generated.

As described above, the reference groove 402 is formed in a linear shape instead of a spiral shape. Therefore, the groove shape measured value 600 and the groove shape measured value 605 of the reference groove 402 have the same shape. On the other hand, as described above, the target groove 302 is formed in a spiral shape while being twisted around the central axis CZ. Therefore, the groove shape measured value 610 of the target groove 302 and the groove shape measured value 615 of the target groove 302 have different shapes. As a result, even if the groove shape measurement value 615 of the target groove 302 and the groove shape measurement value 605 of the reference groove 402 are compared, the target groove 302 cannot be evaluated accurately.

On the other hand, in the present embodiment, as shown in FIG. 22, the measuring unit 20 is first positioned at the position Z6, and the reference groove 402 is measured so that the groove bottom line CB1 and the center of the visual field coincide with each other. The position X1 is obtained. Then, the measuring unit 20 is positioned at the position X1, the measurement is performed by the slit light SL6, and the groove shape measured value 505 of the reference groove 402 is generated. Therefore, according to the present embodiment, even if the reference groove 402 is misaligned or the camera 22 is misaligned with respect to the reference object 400, the groove shape measurement value 505 of the reference groove 402 is accurately obtained. Can be done.

Next, the shaft shape measurement value 530 of the rotor shaft 320 is generated, and the position X2 where the top position of the rotor shaft 320 and the center of the field of view coincide with each other is obtained. Therefore, according to the present embodiment, the position X2 in the X direction corresponding to the central axis CZ can be obtained with high accuracy.

Further, the measuring unit 20 moves in the Z direction while the position in the X direction is maintained at the position X2, and the measurement is performed at a plurality of measuring positions, and the groove bottom line CB2 and the reference groove 402 in the width direction D1 ( The position Z1 orthogonal to FIG. 5) is obtained. This position Z1 can also be said to be a position where the groove bottom line CB2, which is actually a curve, and the slit light SL1 are orthogonal to each other. Then, the measuring unit 20 is positioned at the position Z1, and the groove shape measured value 535 of the target groove 302 is generated. Therefore, according to the present embodiment, it is possible to accurately obtain the groove shape measurement value 535 of the target groove 302 for comparison with the groove shape measurement value 505 of the reference groove 402.

Further, in the present embodiment, the evaluation processing unit 45 evaluates the groove shape of the target groove 302 based on the difference between the groove shape measurement value 505 of the reference groove 402 and the groove shape measurement value 535 of the target groove 302. For example, even if there is a measurement error of the measurement unit 20 due to the surrounding environment and a measurement error that the measurement unit 20 has in principle, these measurement errors are the groove shape measurement value 505 of the reference groove 402 and the groove of the target groove 302. It is included in both the shape measurement value and the 535. Therefore, by obtaining the above difference, these measurement errors are canceled out and disappear. Further, when the shape of the screw rotor 300 changes due to thermal expansion and thermal contraction, the shape of the reference object 400 also changes in the same manner as the screw rotor 300. Therefore, by obtaining the above difference, these components of the shape change are canceled out and disappear. Therefore, according to the present embodiment, the groove shape of the target groove 302 can be evaluated with high accuracy.

(others)
(1) In the embodiment of FIGS. 13 to 15, the embodiment of FIGS. 16 to 18, and the embodiment of FIGS. 19 to 21, the measuring unit 20 is moved in the X direction, but the present invention is not limited to this. For example, the measuring unit 20 may be moved in the Z direction, and the moving direction of the measuring unit 20 is arbitrary. The same result can be obtained by adjusting the length of the slit light emitted from the light source 21 according to the moving direction of the measuring unit 20 and causing the slit light to enter the measurement target in the same manner as in each of the above embodiments. can.

(2) In FIG. 12, the measuring unit 20 is moved in the Z direction, and the height data of the target grooves 302 are measured at n measurement positions. Further, in FIGS. 15, 18, and 21, the height data is measured by the measuring unit 20 every time the measuring unit 20 moves by ΔX or ΔXk.

In this case, the measurement control unit 41 stops the measurement unit 20 every time the movement of a predetermined pitch, causes the light source 21 to emit the slit light, images the reflected light of the slit light with the camera 22, and then the measurement unit after imaging. The movement of 20 may be restarted.

Alternatively, the measurement control unit 41 continuously moves the measurement unit 20 at a constant speed, instantaneously emits the slit light from the light source 21 at each timing when the measurement unit 20 moves at a predetermined pitch, and the camera 22 reflects the slit light. The light may be imaged.

Further, as an alternative, the measurement control unit 41 continuously moves the measurement unit 20 at a constant speed, continuously emits the slit light from the light source 21, and the camera 22 moves at a predetermined pitch at each timing. The reflected light of the slit light may be imaged.

20 Measurement unit 41 Measurement control unit 42 Reference groove processing unit 43 Rotor shaft processing unit 44 Target groove processing unit 45 Evaluation processing unit 100 Evaluation device 300 Screw rotor 302 Target groove 320 Rotor shaft 400 Reference material 402 Reference groove

Claims (7)

An evaluation method for evaluating the shape of a target groove, which is a groove of an evaluation target spirally formed around the central axis on the surface of a measurement target having a columnar rod axis concentric with the central axis.
The shape of the reference groove formed on the surface of the reference object by a measuring unit capable of measuring the shape of the object in a non-contact manner and having the same groove shape as the target groove is measured at the first measurement position, and the lowest position of the reference groove is measured. The first positioning step of obtaining the first deviation amount between the groove bottom line, which is a line connecting the two, and the center of the field of view of the measurement unit, and positioning the measurement unit at the first reference position where the first deviation amount becomes zero.
A reference groove measuring step for measuring the shape of the reference groove by the measuring unit positioned at the first reference position, and a reference groove measuring step.
The shaft shape of the rod shaft is measured by the measuring unit at the second measuring position, and the measuring unit is placed at the second reference position where the amount of deviation between the center of the visual field of the measuring unit and the top position of the rod shaft becomes zero. The second positioning step for positioning and
The measuring unit is moved from the second reference position along the central axis to measure the shape of the target groove at a plurality of measurement positions by the measuring unit, and the difference from the shape of the reference groove is minimized. A third positioning step of obtaining a third reference position, which is a position, and positioning the measuring unit at the third reference position,
A target groove measuring step for measuring the shape of the target groove by the measuring unit positioned at the third reference position, and a target groove measuring step.
An evaluation step for evaluating the shape of the target groove based on the difference between the shape of the target groove measured in the target groove measurement step and the shape of the reference groove measured in the reference groove measurement step, and an evaluation step for evaluating the shape of the target groove.
Evaluation method with. In the first positioning step, the measuring unit is moved in a predetermined direction, the shape of the reference groove is measured by the measuring unit at a plurality of measuring positions including the first measuring position, and the first deviation is measured for each measurement. Each amount is obtained, a first deviation approximate straight line that approximates the relationship between each of the first deviation amounts and the plurality of measurement positions is obtained, and the position of the first deviation approximate straight line at which the first deviation amount becomes zero is obtained. Obtained as the first reference position.
The evaluation method according to claim 1. The first positioning step is performed from the first measurement position based on the angle formed by the moving direction from the first measurement position to the first reference position and the direction in which the groove bottom line extends, and the first deviation amount. The first correction movement amount, which is the movement amount to the first reference position, is obtained, the measurement unit is moved by the first correction movement amount, and the measurement unit is positioned at the first reference position.
The evaluation method according to claim 1. In the second positioning step, the measuring unit is moved in a predetermined direction, and axis measurement values representing the shaft shape of the rod shaft are measured by the measuring unit at a plurality of measurement positions including the second measurement position, and measured. In each case, the axis measurement value is inverted left and right with respect to the center of the field of view of the measurement unit to obtain an inversion measurement value, a difference value between the axis measurement value and the inversion measurement value is obtained, and the difference value and the plurality of are obtained. The difference approximation straight line that approximates the relationship with the measurement position is obtained, the inclination of the difference approximation straight line is obtained, the inclination approximation straight line that approximates the relationship between the inclination and the plurality of measurement positions is obtained, and the inclination becomes zero. The position of the inclination approximate straight line is obtained as the second reference position.
The evaluation method according to any one of claims 1 to 3. In the second positioning step, the measuring unit is moved in a predetermined direction, the shaft shape of the rod shaft is measured by the measuring unit at a plurality of measuring positions including the second measuring position, and the measuring unit is measured for each measurement. The second deviation amount between the center of the field of view and the top position of the rod axis is obtained, and the second deviation approximate straight line that approximates the relationship between the second deviation amount and the plurality of measurement positions is obtained. The position of the second deviation approximate straight line at which the deviation amount becomes zero is obtained as the second reference position.
The evaluation method according to any one of claims 1 to 3. In the second positioning step, the second deviation amount between the center of the field of view of the measuring unit and the top position of the rod axis is obtained, and the angle formed by the direction in which the second deviation amount extends and the direction in which the central axis extends is determined. Based on the second deviation amount, the second correction movement amount, which is the movement amount from the second measurement position to the second reference position, is obtained, and the measurement unit is moved by the second correction movement amount to obtain the second correction movement amount. 2 Position the measuring unit at the reference position.
The evaluation method according to any one of claims 1 to 3. An evaluation device that evaluates the shape of a target groove, which is a groove of an evaluation target spirally formed around the central axis on the surface of a measurement target having a columnar rod axis concentric with the central axis.
A measuring unit that can measure the shape of an object in a non-contact manner,
A reference object having a reference groove having the same groove shape as the target groove formed on the surface thereof,
The shape of the reference groove is measured by the measuring unit positioned at the first measurement position, and the first deviation amount between the groove bottom line, which is a line connecting the lowest positions of the reference groove, and the center of the field of view of the measuring unit is determined. A reference groove processing unit for measuring the shape of the reference groove by the measuring unit in a state where the measuring unit is positioned at a first reference position where the first deviation amount becomes zero.
The shaft shape of the rod shaft is measured by the measuring unit at the second measuring position, and the measuring unit is placed at the second reference position where the amount of deviation between the center of the field of view of the measuring unit and the top position of the rod shaft becomes zero. The rod shaft processing unit for positioning and
The measuring unit is moved from the second reference position along the central axis to measure the shape of the target groove at a plurality of measurement positions by the measuring unit, and the difference from the shape of the reference groove is minimized. A target groove processing unit that measures the shape of the target groove by the measurement unit in a state where the measurement unit is positioned at the third reference position after obtaining a third reference position, which is a position.
An evaluation processing unit that evaluates the shape of the target groove based on the difference between the shape of the target groove measured by the target groove processing unit and the shape of the reference groove measured by the reference groove processing unit.
An evaluation device equipped with.

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