JPH08305424A - Cam grinder - Google Patents

Abstract

PURPOSE: To highly efficiently perform a high-precision working very small in working error at the time of finishing an object to be worked by speedily converging the working error as much as possible. CONSTITUTION: Based on the deviation obtained corresponding to reference time at a present working position N, storage values in previously designated plural storage areas corresponding to reference time before the reference time at the present working position N are rewritten and stored. Besides, based on the respective stored values in the previously designated plural storage areas corresponding to reference time after the reference time at the present working position N, control data at the reference time at the present working position N are corrected. An amount A of separation from the storage areas corresponding to the reference time at the present working position N in the designated storage area is changed and set corresponding to the degree of the following delay of a grinding wheel base from a control command to a moving means. A number (n) of designated storage areas is changed and set corresponding to the degree of dispersion in a main shaft rotating angle at every reference time shown at every time of a grinding working operation each time a main shaft is once rotated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cam grinder for grinding a cam used in a valve operating mechanism of an internal combustion engine, and more particularly to a positioning control device for a grindstone for grinding the cam.

[0002]

2. Description of the Related Art Conventionally, as a device for rotating a main shaft on which a work piece is mounted, relatively moving a grindstone in a direction orthogonal to the main shaft to grind the outer circumference of the work piece into a non-round shape, For example, a cam grinder for grinding a cam in a vehicle engine is known.

In this type of cam grinder, speed control data that sets the relationship between the rotation angle of the spindle and the rotation speed according to a predetermined cam profile, and the relationship between the rotation angle of the spindle and the feed rate of the wheel head. The positioning control data in which is set is stored in advance in the numerical control device (hereinafter, referred to as NC device). Then, based on the control data, N
The C device controls the rotation of the spindle motor for rotating the spindle and the moving motor for moving the grindstone. As a result, the spindle is rotated at a speed according to its rotation angle, and the wheel head is moved back and forth according to the rotation angle of the spindle, so that the cam as the work piece mounted on the spindle has a predetermined cam profile. It is ground to the corresponding non-round shape.

In the above grinding machine, when controlling the rotational speed of the spindle and the feed amount of the grinding wheel head, due to the operation delay of each motor, etc., there is a tracking delay individually in the spindle and the wheel head, and the tracking delay is caused. Due to the delay, there is a problem in that the synchronous relationship between the rotation angle of the spindle and the moving position of the wheel head is displaced. Such a follow-up delay becomes particularly noticeable when the depth of cut to the cam is increased or the spindle rotation speed is increased to improve productivity, and these delays cause a reduction in machining accuracy. There was a problem.

As a measure against such a problem, the control data is corrected in advance in anticipation of the follow-up delay. However, the follow-up delay depends on machining conditions such as the depth of cut and the spindle rotation speed at that time. It was extremely difficult to set when there was a change in the environment due to variations in characteristics of individual grinding machines.

In order to solve the above problems, conventionally, a deviation between the feed amount of the grinding wheel head and the actual wheel head position in the positioning control data is obtained, and based on this deviation, the grinding wheel head for the next processing in the positioning control data is obtained. Correct the feed amount,
Learning control is performed such that the moving motor is controlled based on the correction control data in the next processing. In the learning control that corrects such deviation, the processing error is gradually learned by reflecting the processing while correcting the deviation and is reflected in the control of the next processing, so the processing error is reduced as the processing progresses, Finally, it is possible to obtain a highly accurate cam with little error.

[0007]

However, in the conventional learning control, a large number of learning control times may be required in order to converge the processing error depending on the magnitude of the tracking delay described above. There is a possibility that the processing cannot be efficiently performed in a short time. In some cases, no matter how many times the learning control is performed, the machining error does not converge to a certain value or less, and in today's demand for higher machining accuracy, the conventional learning control does not provide satisfactory machining accuracy. I can't get it.

Moreover, in the conventional learning control, the deviation for the learning control is stored using the reference time for each minute time as an address. That is, conventionally, the wheel head feed amount in the next processing is corrected based on the deviation from the positioning control data of the wheel head feed amount when the spindle has a certain rotation angle at a certain reference time. However, due to the influence of disturbance such as vibration, the spindle rotation angle at a certain reference time shown in the next machining may not match the spindle rotation angle at the same previous reference time. Then, in such a case, the correction data learned in the previous machining is not accurately reflected in the next machining position, and the machining error is a constant value no matter how many times the learning control is performed, as in the case described above. There was a problem that it did not converge to the following.

The present invention has been made to solve the above problems, and an object thereof is to correct a machining error as quickly as possible so that the machining error can be minimized.
It is an object of the present invention to provide a cam grinder that can perform highly accurate machining with extremely low machining error at the time of finishing a workpiece with high efficiency.

[0010]

In order to achieve the above object, in the invention of claim 1, a rotating means for rotating a main shaft on which a workpiece is mounted and a grindstone for grinding a cam surface of the workpiece are provided. Moving means of the grindstone that relatively moves in the direction orthogonal to the spindle, and moves based on control data that sets the relative positional relationship between the rotation angle of the spindle and the feed amount of the grindstone in advance according to the desired machining shape. In a cam grinder for grinding the cam surface of the workpiece into a desired cam profile by rotating the workpiece and performing a plurality of grinding operations, the control means controlling the means by feedback control.
With the movement of the wheel head according to the rotation of the spindle, the control means, at each reference time for each predetermined time indicated during each grinding operation for each rotation of the spindle, the feed amount of the wheel head and the actual amount in the control data. Of the grinding wheel head position and learning means for correcting the control data used in the next grinding operation based on this deviation. This learning means is provided for a plurality of reference times corresponding to one revolution of the spindle. And a storage means having a storage area, which is based on the deviation obtained corresponding to the reference time at the current processing position, and which corresponds to the reference time before the reference time at the current processing position in advance. Rewriting and storing the stored values in the plurality of designated storage areas, and based on the respective stored values in the plurality of designated storage areas corresponding to the reference time after the reference time at the current machining position, Present Corresponding to the reference time at the current processing position of the specified storage area according to the correction means for correcting the control data at the reference time at the work position and the degree of the follow-up delay of the wheel head to the control command to the moving means. The amount of separation from the storage area to be changed is set, and the number of storage areas to be specified is changed and set according to the degree of variation in the spindle rotation angle at each reference time indicated during each grinding operation for each rotation of the spindle. And a setting means for setting.

According to the invention of claim 2, in claim 1,
The storage means rewrites the stored value based on a value obtained by weighting the obtained deviation with a predetermined weighting coefficient, and the correction means weights each storage value in the plurality of storage areas with a predetermined weighting coefficient. The control data is corrected on the basis of the total sum of the values.

According to a third aspect of the present invention, in the first or second aspect, the setting means has a larger follow-up delay of the wheel head,
The separation amount of the designated storage area is set to a large value. According to a fourth aspect of the present invention, in any one of the first to third aspects, the setting unit sets a smaller number of storage areas to be designated as the variation in the spindle rotation angle is smaller.

According to a fifth aspect of the present invention, there are provided a rotating means for rotating a main shaft on which a work piece is mounted, and a grindstone stand for relatively moving a grindstone for grinding a cam surface of the work piece in a direction orthogonal to the main shaft. A moving means, and a control means for feedback-controlling the moving means based on control data in which the relative positional relationship between the rotation angle of the spindle and the feed amount of the grindstone is set in advance according to the desired machining shape, In the cam grinder that grinds the cam surface of the workpiece to a desired cam profile by rotating the grinding wheel a plurality of times, the control means controls movement of the wheel head according to the rotation of the spindle. Along with this, there is provided a learning means for obtaining the deviation between the feed amount of the grinding wheel head and the actual wheel head position in the control data, and correcting the control data used in the next grinding operation based on this deviation. The means is a storage means having a plurality of storage areas respectively corresponding to the respective processing positions on the workpiece by the grindstone, and the storage means is based on the deviation obtained corresponding to the current processing position, Rewriting and storing the stored value in the storage area, and correction means for correcting the control data at the current machining position based on the stored value in the predetermined storage area, each storage area of the storage means ,
The stored value is assigned according to the rotation angle of the spindle.

According to the invention of claim 6, in claim 5,
The correction means corrects the control data at the current processing position based on the stored values in a plurality of storage areas designated in advance corresponding to the processing position after the current processing position.

According to a seventh aspect of the present invention, in the fifth or sixth aspect, the storage means pre-designates a machining position prior to the current machining position based on the deviation obtained corresponding to the current machining position. The stored values in the plurality of stored storage areas are rewritten and stored.

[0016]

Therefore, according to the first aspect of the invention, in the process of rotating the workpiece and performing the grinding operation a plurality of times, the spindle 1
At each reference time for each predetermined time shown during each grinding operation for each rotation, the deviation between the feed amount of the wheel head and the actual wheel head position in the control data is calculated, and the next grinding operation is performed based on this deviation. The control data used is corrected. Specifically, based on the deviation obtained corresponding to the reference time at the current processing position on the workpiece by the grindstone, a pre-specified corresponding to the reference time before the reference time at the current processing position The stored values in the plurality of storage areas are rewritten and stored. Further, the control data at the reference time at the current processing position is corrected based on the stored values in the plurality of storage areas designated in advance corresponding to the reference time after the reference time at the current processing position.

Here, the amount of separation from the storage area corresponding to the reference time at the current processing position of the specified storage area is:
The setting is changed and set according to the degree of the delay in the follow-up of the wheel head to the control command to the moving means. That is, the correction is made based on the stored value in the storage area corresponding to the machining position ahead of the current machining position by a predetermined amount according to the degree of the tracking delay of the grinding wheel head. Also, the number of storage areas specified is
It is changed and set according to the degree of variation of the spindle rotation angle at each reference time shown during each grinding operation for each spindle rotation.

As a result, the optimum learning control can be executed according to the follow-up delay of the wheel head and the variation of the spindle rotation angle, and the processing error can be converged with the least number of learning times and the processing error. Can be reliably converged within the allowable range.

According to the second aspect of the present invention, the control data is properly corrected based on the sum of the values obtained by weighting the respective storage values in the plurality of storage areas with the predetermined weighting coefficient.
According to the invention of claim 3, as the follow-up delay of the grinding wheel head is larger, the separation amount of the designated storage area is set to be larger, so that the control data at the reference time at the current processing position can be processed with a larger distance. It is possible to predict and correct the tendency of deviation in the position. Therefore, it is possible to quickly deal with a large follow-up delay, and the processing error converges quickly.

According to the fourth aspect of the present invention, the smaller the variation of the spindle rotation angle is, the smaller the number of storage areas to be designated is, so that the correction amount becomes more concentrated and the machining error converges faster. The number of learning controls is small.

According to the inventions of claims 5 to 7, learning control based on the spindle rotation angle is performed by allocating the stored value to each storage area of the storage means in correspondence with the rotation angle of the spindle. Therefore, even if there are variations in the spindle rotation angle, it is possible to extremely reduce the number of storage areas to be specified, and at each machining position specified by the rotation angle of the spindle on which the workpiece is mounted, It is possible to accurately reflect the correction data learned in the processing on the control data at the current processing position.

[0022]

【Example】

(First Embodiment) A first embodiment of the present invention will be described below with reference to FIGS.

As shown in FIGS. 1 and 2, the work support 1 is mounted on the upper surface of one side of the base 2 by a moving mechanism (not shown).
It is movably supported in the left-right direction (Z direction). The spindle headstock 3 is disposed on the upper surface of the work support base 1 and includes a spindle 4 for detachably supporting one end of the camshaft W and a spindle motor including a servomotor as a rotating means for rotating the spindle 4. It is equipped with 5. Further, on the cam shaft W, a plurality of cams Wa as workpieces are formed at predetermined intervals in the axial direction, and the outer peripheral surfaces of these cams Wa are surfaces Wb to be ground.

The holder 6 is arranged on the upper surface of the work support 1 so that the distance between the holder 6 and the main shaft 4 can be adjusted, and the camshaft W is rotatable between the main shaft 4 and the holder 6 so as to extend in the Z direction. And it is detachably supported. Then, the cam shaft W is rotated in a predetermined direction in accordance with the driving of the spindle motor 5 in this supported state. The encoder 7 is attached to the spindle motor 5, and a detection signal from the encoder 7 is input to an NC device 18 described later.

The grindstone base 8 has a camshaft W on the base 2.
It is supported so as to be movable in the horizontal direction (X direction) orthogonal to the axis line of. A moving motor 9 composed of a servo motor is attached to a side portion of the base 2, and the ball screw 10 is rotated by the moving motor 9 to move the grindstone base 8 in a direction toward or away from the camshaft W. . In this embodiment, the moving motor 9 and the ball screw 10 form a moving means. The encoder 11 is attached to the moving motor 9, and a detection signal from the encoder 11 is input to an NC device 18 described later. The rotary grindstone 12 as a tool is rotatably supported by a spindle 13 at one end of the grindstone base 8 so as to face the camshaft W. The grindstone motor 14 is disposed on the grindstone base 8,
The grindstone motor 14 rotates the grindstone 12 in one direction via the pulleys 15 and 16 and the belt 17.

The NC device 18 constituting the control means, the learning means and the setting means is for controlling the operation of the entire device. This NC device 18 is a CP that performs various arithmetic processes.
It has a U (central processing unit) 19, a ROM (read only memory) 20 that stores programs for controlling the operation of the entire device, and a RAM (random access memory) 21 that temporarily stores various information. There is.

The RAM 21 stores spindle speed control data for controlling the rotation speed of the spindle 4 and grinding wheel position control data for controlling the position of the grinding wheel head 8 in the X direction according to a predetermined cam profile. Is stored in advance. As illustrated in FIG. 3, the spindle speed control data indicates the relationship between the rotation angle and the rotation speed of the spindle 4, and the grinding wheel position control data indicates the rotation angle of the spindle 4 and the feed amount (moving position) of the grinding wheel mount 8. The relationship is set, for example, for each 1 degree of the main axis angle.

Then, at the time of grinding, the NC device 1
Reference numeral 8 denotes a reference time generator 23, which will be described later, as shown in FIG.
Accordingly, for example, in accordance with the reference time t _N shown every 1 ms, based on the spindle speed control data and the grinding wheel head position control data shown in FIG. 3, an interpolation calculation using a predetermined interpolation formula (for example, spline interpolation calculation) is performed. , The rotation speed command value of the spindle 4 corresponding to the current angle σ _N of the spindle 4 and the wheel head 8
The movement command value B _N is calculated. Further, the NC device 18 detects the present angle σ _N of the spindle 4 at that time by the encoder 7. FIG. 5 shows the obtained movement command value B _N of the grinding stone head 8. The rotation speed command value of the spindle 4 is also obtained in the same manner, but the illustration is omitted. Incidentally, as will be described later, the deviation data Z _N in FIG. 4 is obtained in correspondence with the reference time t _N so as to correct the prediction error of the movement command value B _N of the wheel head 8, and is calculated in each ring memory described later. It is stored in the storage area. Further, the NC device 18 detects the moving position of the grinding wheel base 8 at that time in the X direction by the encoder 11 in correspondence with the reference time t _N.

Then, the NC device 18 controls the rotation of the spindle motor 5 and the moving motor 9 while rotating the grindstone 12 based on the command value as shown in FIG. As a result, the cam Wa (that is, the main shaft 4) is rotated at a speed according to the rotation angle thereof, and the grinding wheel head 8 is moved back and forth in the X direction according to the rotation angle of the main shaft 4. In the graph of FIG. 5, the spindle rotation angle when the cam Wa is in the state of FIG. 6 is 0 degree. Further, the NC device 18 controls the movement of the work support table 1 in the Z direction to dispose the predetermined cam Wa opposite the grindstone 12. As a result, the predetermined cam Wa is ground into a non-round shape corresponding to the predetermined cam profile.

FIG. 7 shows a control block diagram relating to the control of the moving motor 9 executed by the NC device 18. As shown in FIG.
This storage unit 22 constitutes a part of the AM 21.
The above-mentioned grindstone position control data is stored in.
The reference time generator 23 is for indicating the reference time every 1 ms, for example. Then, in the control data extractor 24, based on the wheel head position control data in the control data storage 22, as described above, the wheel head 8 at each reference time
The movement command value of the position in the X direction is calculated for each reference time. As described above, this movement command value is set as a value corresponding to the rotation angle of the spindle 4 at each reference time.

The movement command value of the grinding wheel base 8 thus obtained is
It is given to the adder 25. In the adder 25, an error prediction correction value described later is added to the given movement command value to correct the movement command value. Then, the corrected movement command value is output to the first subtractor 26. On the other hand, in the position counter 27, the current value of the X-direction position of the wheel head 8 is obtained based on the detection signal from the encoder 11 and output to the first subtractor 26. Then, the first subtractor 26
Then, the deviation between the corrected movement command value from the adder 25 and the current value of the X-direction position of the wheel head 8 from the position counter 27 is obtained. The deviation is determined by the deviation value determining means 35.
Thus, it is determined whether or not the value is within a predetermined value set in advance.

Next, when the deviation is given to the speed command setting unit 28, the speed command setting unit 28 sets the speed command output to the moving motor 9 via the motor driver 29. As described above, the rotational position of the moving motor 9, that is, the X-direction position of the grindstone 8 is controlled.

Therefore, in the above control process, the adder 25
In, the error prediction correction value is added to the movement command value based on the wheel head position control data, so that the error command correction is performed on each movement command value.

On the other hand, the current value of the X-direction position of the grinding wheel head 8 which is the output of the position counter 27 is also given to the second subtractor 30. In the second subtractor 30, the grindstone 8
The deviation between the present value of the X-direction position and the movement command value of the X-direction position of the grinding wheel head 8 given from the control data extractor 24 is obtained at each reference time, and the deviation is given to the correction means 31.

The correction means 31 is an error prediction correction means 32.
And a deviation data storage device 33 as a storage means. In the error prediction correction means 32, the second subtractor 30
The error prediction correction value is obtained by applying the calculation formula (1), an example of which will be described later, to the deviation between the current value of the X-direction position of the grinding wheel head 8 and the movement command value given by Then, the error prediction correction value obtained by the error prediction correction means 32 is
It is given to the adder 25 by the error prediction correction value extractor 34.

On the other hand, the deviation data storage unit 33 is composed of a ring memory and a rewriting means for rewriting the contents of the ring memory. FIG. 8 shows a conceptual layout diagram of the ring memory.
The storage area in this ring memory is provided corresponding to each reference time indicated by the reference time generator 23, and the number thereof corresponds to the number of reference times generated during one rotation of the cam Wa. It is equivalent. As shown in FIG. 8, each storage area in the ring memory has a one-to-one correspondence with a processing position corresponding to each reference time on the cam Wa that is the workpiece.
Is set according to. In other words, each storage area in the ring memory is set in one-to-one correspondence with the spindle rotation angle corresponding to each reference time. That is, assuming that the current processing position of the cam Wa is N, in the ring memory, the traveling direction of the processing position (direction opposite to the rotational direction S of the cam Wa).
A storage area corresponding to the positions of N + 1, N + 2, N + 3, N + 4 ... Is set along with, and N-1, N-2, N-3, N along the direction opposite to the traveling direction of the machining position.
A storage area corresponding to the position of -4 ... Is set.

In this case, in this embodiment, in the ring memory, in the storage area set along the traveling direction of the machining position and the opposite direction thereof, calculation processing of an error prediction correction value described later and rewriting of the stored value are performed. The number n of storage areas designated for processing can be changed and set.

Next, an example of processing in the error predicting / correcting means 32 will be described. In the error prediction correction means 32, the deviation data storage unit 3 is calculated using, for example, the following calculation formula (1).
On the basis of the data relating to the deviation generated in the pre-machining operation stored in the ring memory of No. 3, what kind of deviation occurs in the non-machining position where the machining progresses after the current machining position, and the tendency of the deviation is predicted and added. Then, the correction value of the movement command value based on the wheel head position control data at the current processing position is set. In other words, the error prediction correction means 32 obtains a correction value for correcting the movement position of the grinding wheel base 8 in the X direction. Here, it is assumed that, for example, seven storage areas are specified in the ring memory along the traveling direction of the machining position including the current machining position of the cam Wa. F _N = E _N + (K ₁₁ × Z [N] + K ₁₂ × Z [N + 1] + K ₁₃ × Z [N + 2] + K ₁₄ × Z [N + 3] + K ₁₅ × Z [N + 4] + K ₁₆ × Z [N + 5] + K ₁₇ × Z [N + 6]) × K ₂ (1) F _N : Error prediction correction value at N position E _N : Deviation at N position K ₂ : Depends on individual processing device, type of cam Wa and processing speed determined constant Z [N] ~Z [N + 6]: N~N + 6 stored value in the ring memory corresponding to the position (the previous processing time values based on the deviation data) K ₁₁ ~K _17: weighting coefficient (where, K ₁₁ + K ₁₂ + K ₁₃ +
K ₁₄ + K ₁₅ + K ₁₆ + K ₁₇ = 1) That is, the stored value is simultaneously output from the predetermined storage area of the ring memory of the deviation data storage unit 33, and the stored value corresponding to the unprocessed position, that is, the current processing position is N Then, N, N + 1, N + 2, N + 3, N + 4 ...
Stored values Z [N], Z [N + 1], Z corresponding to the position of
[N + 2], Z [N + 3], Z [N + 4], ... Are weighted by a predetermined weighting coefficient (for example, Hanning window function) and added to the deviation E _N at the current machining position, resulting in the current machining position. The error prediction correction value F _{N at} is calculated. In other words, the error prediction correction value at each current machining position affects the deviation of the current machining position as the magnitude of the deviation that is expected to occur in the plurality of stored values corresponding to each unmachined position and the tendency in that direction. The error prediction correction is performed accordingly.

Further, as the machining progresses in the above process, a predetermined plurality of n storage areas of the ring memory of the deviation data storage unit 33 corresponding to the already machined machining positions on the cam Wa are stored in the following areas. The stored value rewriting process shown in equation (2) is simultaneously performed. Here, it is assumed that, for example, seven storage areas are designated in the ring memory along the direction opposite to the traveling direction of the machining position including the current machining position of the cam Wa. Z [N] = Z [N ] + K 21 × E N × K 1 Z [N-1] = Z [N-1] + K 22 × E N × K 1 Z [N-2] = Z [N-2 _{] + K 23 × E N ×} K 1 Z [N-3] = Z [N-3] + K 24 × E N × K 1 Z [N-4] = Z [N-4] + K 25 × E N × K _{1 Z [N-5] =} Z [N-5] + K 26 × E N × K 1 Z [N-6] = Z [N-6] + K 27 × E N × K 1 ··· (2) Z [N] to Z [N-6]: Stored value in the ring memory corresponding to N to N + 6 positions E _N : Deviation at N position K ₁ : Constant determined by individual machining device, type of cam Wa and machining speed K _{21 to} K ₂₇ : Weighting coefficient (however, K ₂₁ + K ₂₂ + K ₂₃ +
K ₂₄ + K ₂₅ + K ₂₆ + K ₂₇ = 1) Also, in the above-described error prediction correction value calculation processing and storage value rewriting processing, as shown in FIG. Each stored value in is set to have a smaller weighting from the central one toward both sides. In this case, in this embodiment, the separation amount A from the storage area of the ring memory corresponding to the current machining position N to the central storage area having the largest weight can be changed and set. The separation amount A is A ≧
(N / 2) +1 is established, and is set to such an extent that the storage area corresponding to the current machining position N is not too far from the storage area.

Next, the grinding operation for the cam Wa executed by the NC unit 18 will be described with reference to the flowchart of FIG. First, before starting the machining operation,
In step S1, the number n of storage areas and the separation amount A in the ring memory, which are designated during the calculation processing of the error prediction correction value and the rewriting processing of the storage value, are set to predetermined values, and the weighting coefficient is set accordingly. It
Next, in step S2, the storage value in each storage area in the ring memory is initialized to "0". When the machining operation is started in this state, first, in step S3, the spindle 4 is started to rotate according to the spindle speed control data. At the same time, in step S4,
The wheel head 8 is started to move back and forth according to the wheel head position control data.

In this state, the error prediction correction means 32 calculates an error prediction correction value. That is, first in step S5, for example, the current processing position (grinding point)
Is set to N = 1. Subsequently, in step S6, a deviation E _N between the movement command value of the wheel head 8 determined based on the wheel head position control data and the current position of the wheel head 8 from the position counter 27 is calculated. Next, step S7
In was determined deviation E _N and error data storage 33
The error prediction correction value F _N is calculated according to the equation (1) based on the stored value in the predetermined storage area of the ring memory.

Then, in step S8, the moving motor 9 is controlled based on the calculated error prediction correction value F _N , and the grindstone base 8 is moved to the predetermined X direction position. At the same time, in step S9, the stored value in the predetermined storage area in the ring memory of the deviation data storage unit 33 is rewritten according to the above equation (2).

Thereafter, in step S10, the cam W
It is determined whether or not a has been rotated once. If it has not been rotated once yet, the process proceeds to step S11, and a new current grinding point associated with the movement of the grinding point is set to N = N + 1. Then, returning to step S6, the cam Wa is set to 1
The processes of steps S6 to S11 are repeated until rotated.

After that, if the decision result in the step S10 is YES, the process advances to a step S12, and the deviation value determining means 35 determines whether or not each deviation for one revolution of the cam Wa is within a predetermined value set in advance. Is determined. Here, if the deviation is within the predetermined value, the machining operation is terminated at that time, and if the deviation is not within the predetermined value, the process proceeds to step S13 and the cam W
It is determined whether or not the number of rotations of a (that is, the number of times of learning) has reached a predetermined number set in advance. If the predetermined number of times has not been reached, the process returns to step S5 to continue the grinding operation as it is, and the current grinding point is again set to N =
It is set to 1, and the processing of steps S5 to S13 is repeated. When the number of times reaches the predetermined number, it is determined that the number n of storage areas, the distance A and the weighting coefficient set in step S1 are not appropriate, and the process returns to step S1. Then, the number n of storage areas, the distance A, and the weighting coefficient are reset, and the processes of steps S1 to S13 are repeated.

FIG. 10 is a diagram for explaining the status of rewriting the stored value in the ring memory in step S9. In addition, in this figure, for ease of explanation,
One rotation of the cam is divided into 20 parts. As shown by the diagonal lines in the drawing, the rewriting of the stored value is performed, for example, in the ring memory for each of seven storage areas corresponding to the current grinding point of the cam Wa and the six already ground points before that. Has been done. When calculating the error prediction correction value F _N in step S7, the stored value in each storage area corresponding to a predetermined number of unground points after the current ground point of the cam Wa is referred to in the ring memory. .

As described above, in the present embodiment, based on the stored value stored in the storage area corresponding to the machining position after the current machining position of the deviation data storage unit 33, machining is not progressed after the current machining position. What kind of deviation occurs at the machining position, the tendency of the deviation is predicted, and the movement command value based on the wheel head position control data at the current machining position is corrected to perform the machining. For this reason, it is possible to reduce the machining error as the machining progresses by following the ever-changing machining conditions.

Further, in this embodiment, in order to perform the above-described error prediction correction value calculation processing and stored value rewriting processing, in the ring memory, the processing position is centered on the storage area corresponding to the current processing position N. A predetermined number n of storage areas are designated in advance along the traveling direction and the opposite direction. In this case, in this embodiment, it is possible to change and set the separation amount A from the storage area corresponding to the current machining position N to the central storage area having the highest weighting among the specified predetermined number n of storage areas. It is configured. This is preset by experiments or trial machining before actual machining operation according to the degree of delay of follow-up of the grindstone 8 with respect to the control command to the moving motor 9 in the movement control of the grindstone 8. It is a thing.

For example, when the follow-up delay of the grinding wheel head 8 is large, the separation amount A of the storage area in the ring memory is set to a large value, and the storage value to be referred to when rewriting and calculating the error prediction correction value is increased from the current machining position. It should be separated. With this configuration, the movement command value based on the grinding wheel head position control data at the current processing position can be corrected by predicting the tendency of the deviation at the further unprocessed position. Therefore, even a large tracking delay can be dealt with appropriately and quickly, and the processing error can be quickly converged with a small number of learnings. Therefore, it is possible to efficiently perform the machining in a short time, and it is possible to obtain the high-precision cam Wa with extremely few machining errors in the finishing machining.

Further, in this embodiment, the number n of storage areas designated in the ring memory can be changed and set in the process of calculating the error prediction correction value and the process of rewriting the stored value. This is set in advance by experiments or trial machining before performing the actual machining operation, depending on the degree of variation in the spindle rotation angle at each reference time indicated during each grinding machining operation for each revolution of the spindle 4. It is a thing.
The variation of the spindle rotation angle means, for example, the spindle rotation angle at a certain reference time shown in the next machining,
This is the deviation from the spindle rotation angle at the same reference time indicated during the previous machining.

For example, when there is a large variation in the rotation angle of the spindle, the number n of storage areas designated in the ring memory is set to be large so that the number of storage values that can be referred to when rewriting and calculating the error prediction correction value becomes large. To With this configuration, the movement command value based on the wheel head position control data at the current machining position can be corrected by incorporating the tendency of the deviation at the non-machining position over a wider range. As a result, even if the variation is large, in other words, even if the spindle rotation angle at a certain reference time shown in the next processing is significantly different from the spindle rotation angle at the same reference time shown in the previous processing, The error can be reliably converged within the allowable range.

Further, for example, when the variation in the spindle rotation angle is small, the number n of storage areas designated in the ring memory is set to be small, and the number of storage values that can be referred to when rewriting and calculating the error prediction correction value is small. To be By doing so, it becomes possible to correct the movement command value based on the grinding wheel head position control data at the current machining position by taking in the necessary range without taking the tendency of deviation at the unmachined position more than necessary. . As a result, the processing error can be converged as quickly as possible.

FIG. 8 exemplifies a state in which the separation amount A of the storage area designated in the ring memory and the number n of the storage areas designated are set. As illustrated in the figure, it is assumed that by setting the separation amount A of the designated storage area, the central storage area having the highest weighting is set to correspond to the processing positions N + 3 and N-3, respectively. In this case, if the number n of designated storage areas is set to “7”, the storage areas corresponding to the machining positions N + 3 and N−3 for calculation processing of error prediction correction values and rewriting processing of storage values. The storage areas corresponding to the machining positions N to N + 6 and N to N-6, respectively, are designated with the center as the center. At this time, in the range of the designated storage area, the weighting of each storage value and the deviation is as shown by the solid line L1 in FIG. 8 according to the Hanning window function, for example.

Further, it is assumed that the central storage area having the largest weight is set to the one corresponding to the processing positions N + 3 and N-3, respectively, by setting the separation amount A of the designated storage area, as described above. In this case, if the number n of storage areas to be designated is set to "5", the storage areas corresponding to the machining positions N + 3 and N-3 for calculation processing of error prediction correction values and rewriting processing of storage values. The storage areas corresponding to the machining positions N + 1 to N + 5 and N-1 to N-5 are designated with the center as the center. At this time, weighting of each storage value and deviation in the designated storage area range is shown by a chain line L2 in FIG. 8 according to, for example, a Hanning window function.

That is, as is clear from the comparison between the solid line L1 and the chain line L2 in FIG. 8, the smaller the number n of storage areas to be designated is set, the larger the weighting corresponding to the central storage area becomes, and both sides thereof become larger. The difference from the weighting corresponding to the storage area becomes larger. Therefore, when the above-described variation in the spindle rotation angle is small, if the number n of storage areas to be designated is set small, the influence of the storage value in the central storage area that is most necessary for learning control becomes large, Since the influence of the stored values in the other storage areas becomes small, the processing error converges quickly.

As described above, in this embodiment, the optimum learning control can be executed in accordance with the follow-up delay of the grinding wheel head 8 and the variation in the spindle rotation angle, and the machining error can be converged with the least number of learning times. In addition, the processing error can be reliably converged within the allowable range.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. 11 and FIG. 4 described in the first embodiment.

In the first embodiment, each storage area in the ring memory of the deviation data storage unit 33 has a cam Wa corresponding to each reference time indicated by the reference time generator 23.
It is set corresponding to the above machining position. In other words, a deviation value for learning control is stored in each storage area of the ring memory with the reference time as an address. On the other hand, in the second embodiment, the deviation value for learning control is stored in each storage area of the ring memory with the rotation angle of the spindle 4 as an address.

That is, as shown in FIG. 11, in the wheel head position control data, the wheel head position is set in correspondence with the spindle rotation angle, but in the second embodiment, it corresponds to the spindle rotation angle. The deviation value for learning control is stored.

The storage method will be described here. As shown in FIG. 4, first, the grinding wheel head position control data shown in FIG. 11 is converted to the reference time t _N shown by the reference time generator 23. Based on the interpolation calculation (for example, spline interpolation calculation) using a predetermined interpolation formula,
The movement command value B _N of the wheel head 8 corresponding to the present angle σ _N of is calculated. Next, deviation data Z _N corresponding to the movement command value B _N is stored in correspondence with the spindle rotation angle θ _N shown in FIG. 11 in order to correct the movement command value B _N of the grinding wheel head 8 with a prediction error. Based on the deviation data G _N, it is obtained by an interpolation calculation using a predetermined interpolation formula.

In addition to the deviation data Z _N obtained at the current machining position, a predetermined number of deviation data Z _{N + 1,} Z _{N + 2} ...
Rotation angle sigma _{N + 1} of the current angle sigma _N after the main shaft _4, σ _{N + 2} ... calculated from the Get therewith deviation data G _{N + 1,} is determined by interpolation on the basis of the G N _{+ 2} .... Then, the deviation data Z _N at the current machining position obtained in this way,
Based on a predetermined number of deviation data Z _{N + 1,} Z _{N + 2} ... In the machining positions after the current machining position, the movement command value B _N of the grinding wheel head 8 is calculated according to the equation (1) in the first embodiment. The prediction error is corrected. Then, the movement motor 9 is controlled on the basis of the movement command value B _N corrected with the prediction error, and the grindstone base 8 is moved to a predetermined X direction position.

On the other hand, the deviation between the movement command value B _N of the grindstone 8 at the current machining position and the current position of the grindstone 8 is obtained,
According to the equation (2) in the first embodiment, the deviation is given a predetermined weighting, and the deviation data Z _N at the current machining position is obtained.
And a predetermined number of deviation data Z _N-1, Z _N-2, ... At the machining positions before the current machining position are added. Then, the newly weighted deviation data Z _N, Z _N-1, Z _N-2, ... Are converted to deviation data G _N, corresponding to the spindle rotation angle θ _N shown in FIG.
In order to store as G _N-1, G _N-2 ..., Interpolation calculation is performed again in order from the deviation data G _N near the current angle σ _N corresponding to the deviation data Z _N.

As described above, in the second embodiment, the learning control based on the spindle rotation angle is performed by storing the data regarding the deviation for the learning control in correspondence with the rotation angle of the spindle 4. I am trying. Therefore, even if there are variations in the spindle rotation angle as described in the first embodiment, it is possible to extremely reduce the number of designated storage areas, and the rotation angle of the spindle 4 on which the cam Wa is mounted can be changed. At each specified machining position, the deviation data generated during the previous machining can be accurately reflected in the movement command value based on the wheel head position control data at the current machining position. Therefore, even if the spindle rotation angle at a certain reference time shown in the next machining does not match the spindle rotation angle at the same reference time shown in the previous machining, the learning control is not adversely affected. Therefore, in the second embodiment, the processing error can be converged with a smaller number of times of learning, and the processing error can be made extremely small.

The present invention is not limited to the above-mentioned embodiment, and the constitution of each part may be modified and embodied as follows. (1) In the above-described embodiment, the error prediction correction is performed when the position of the wheel head 8 is controlled, but the error prediction correction is performed when the speed of the spindle 4 is controlled.

[0064]

As described in detail above, the present invention has the following excellent effects. According to the invention of claim 1, the optimum learning control can be executed according to the follow-up delay of the grinding wheel head and the variation of the spindle rotation angle, and the machining error can be converged with the least number of learning. The processing error can be reliably converged within the allowable range.

According to the second aspect of the present invention, the control data is properly corrected based on the sum of the values obtained by weighting the respective storage values in the plurality of storage areas with the predetermined weighting coefficient.
According to the third aspect of the present invention, the control data at the current machining position can be predicted and corrected by the tendency of the deviation at the further unmachined position, and a large follow-up delay can be quickly dealt with. Therefore, the processing error can be quickly converged with a small number of learnings.

According to the fourth aspect of the present invention, the control data at the current machining position can be corrected by incorporating only the necessary range without taking the tendency of the deviation at the unmachined position more than necessary. The processing error can be quickly converged by the number of learnings.

According to the inventions of claims 5 to 7, at each machining position specified by the rotation angle of the spindle on which the workpiece is mounted, the correction data learned in the previous machining is used as the control data at the current machining position. Can be reflected accurately, and the processing error can be quickly converged with a small number of learnings, and the processing error can be made extremely small.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view showing an embodiment in which the present invention is embodied in a grinding machine.

FIG. 2 is a plan view of a grinder.

FIG. 3 is an explanatory diagram showing spindle speed control data and grinding wheel head position control data.

FIG. 4 is an explanatory diagram showing each data obtained corresponding to a reference time.

FIG. 5 is a graph showing a movement command value of a grinding wheel head with respect to a spindle rotation angle.

FIG. 6 is a partial side view showing a cam and a grindstone on a spindle.

FIG. 7 is a control block diagram relating to control of a moving motor.

FIG. 8 is a conceptual diagram illustrating a ring memory in a deviation data storage device.

FIG. 9 is a flowchart showing a grinding operation for the cam.

FIG. 10 is an explanatory diagram showing a state of rewriting a stored value in a ring memory.

FIG. 11 is an explanatory diagram showing a deviation allocation state in the second embodiment.

[Explanation of symbols]

4 ... Spindle, 5 ... Spindle motor as rotating means, 7 ... Encoder, 8 ... Grinding wheel mount, 9 ... Moving motor configuring moving means, 10 ... Ball screw configuring moving means,
11 ... Encoder, 12 ... Rotating grindstone, 18 ... Control means,
NC device constituting learning means and setting means, 22 ... control data storage, 23 ... reference time generator, 31 ... correction means, 32 ... error prediction correction means, 33 ... deviation data storage as storage means, Wa ... Cam as work piece, Wb
… Surface to be ground.

Claims (7)

[Claims] 1. A rotating means for rotating a main shaft on which a work piece is mounted, a moving means for moving a grindstone for grinding a cam surface of the work piece in a direction orthogonal to the main shaft, and a desired means. And a control means for feedback-controlling the moving means on the basis of control data in which the relative positional relationship between the rotation angle of the spindle and the feed amount of the grindstone is set in advance according to the machining shape. In a cam grinder that grinds a cam surface of a workpiece into a desired cam profile by performing a single grinding operation, the control means rotates the spindle one revolution in accordance with the movement of the wheel head according to the rotation of the spindle. At each reference time for each predetermined time shown during each grinding operation, the deviation between the feed amount of the wheel head and the actual wheel head position in the control data is obtained, and the next grinding operation is performed based on this deviation. A learning means for correcting the control data used in step S1 is provided. The learning means includes a storage means having a plurality of storage areas respectively corresponding to respective reference times for one rotation of the spindle, and the storage means is a current processing position. Based on the deviation obtained corresponding to the reference time in, to rewrite and store the storage value in a plurality of pre-designated storage areas corresponding to the reference time before the reference time at the current machining position, Based on each stored value in a plurality of storage areas designated in advance corresponding to the reference time after the reference time at the current processing position,
A correction means for correcting the control data at the reference time at the current processing position, and a reference time at the current processing position of the specified storage area according to the degree of the delay in following the grinding head to the control command to the moving means. The amount of separation from the storage area corresponding to is set, and the number of storage areas to be specified is determined according to the degree of variation of the spindle rotation angle at each reference time indicated during each grinding operation for each rotation of the spindle. A cam grinder equipped with setting means for changing and setting. 2. The storage unit rewrites the stored value based on a value obtained by weighting the obtained deviation with a predetermined weighting coefficient, and the correction unit sets a predetermined value for each stored value in a plurality of storage areas. The cam grinder according to claim 1, wherein the control data is corrected based on the sum of the values weighted by the weighting coefficient of. 3. The cam grinder according to claim 1, wherein the setting unit sets the separation amount of the designated storage area to be larger as the follow-up delay of the wheel head is larger. 4. The cam grinder according to claim 1, wherein the setting unit sets the number of storage areas to be designated to be smaller as the variation of the spindle rotation angle is smaller. 5. A rotating means for rotating a spindle on which a workpiece is mounted, a means for moving a grindstone for relatively moving a grindstone for grinding a cam surface of the workpiece in a direction orthogonal to the spindle. And a control means for feedback-controlling the moving means on the basis of control data in which the relative positional relationship between the rotation angle of the spindle and the feed amount of the grindstone is set in advance according to the machining shape. In a cam grinder that grinds a cam surface of a workpiece into a desired cam profile by performing a single grinding operation, the control means may move the grinding wheel head according to the rotation of a spindle to control the control data. Is provided with learning means for obtaining a deviation between the feed amount of the grinding wheel head and the actual position of the grinding wheel head, and correcting the control data used in the next grinding processing operation based on this deviation. Storage means having a plurality of storage areas corresponding to each processing position on the workpiece,
The storage means rewrites and stores the stored value in the predetermined storage area based on the deviation obtained corresponding to the current processing position, and the current processing based on the stored value in the predetermined storage area. A cam grinder comprising: a correction unit that corrects control data at a position, and a storage value is assigned to each storage area of the storage unit in correspondence with a rotation angle of a spindle. 6. The correction means corrects the control data at the current machining position based on the respective stored values in a plurality of predesignated storage areas corresponding to the machining positions after the current machining position. Cam grinder described in. 7. The storage means rewrites stored values in a plurality of predesignated storage areas corresponding to processing positions before the current processing position based on the deviation obtained corresponding to the current processing position. The cam grinder according to claim 5, wherein the cam grinder is stored as a memory.