JP6087328B2 - Additive manufacturing equipment - Google Patents

Description

  The present invention relates to an additive manufacturing apparatus.

  In the additive manufacturing of metal by laser light, a very thin material powder layer is formed on a modeling table that can be moved in the vertical direction. A desired shaped object is formed by repeating the process of sintering the powder.

  A layered manufacturing apparatus for performing such layered modeling has a large number of heat sources, and thermal displacement occurs in various members due to the heat from the heat source. As a result, the laser beam irradiation position is shifted. May occur.

  In Patent Document 1, in order to correct such a deviation, a reference mark is set at a position adjacent to the modeling area, and the positional deviation is detected by measuring the reference mark before and during the modeling through the scanning optical system. Correction is being performed. In order to measure the fiducial mark, the imaging unit is moved and inserted into the optical path by using a moving mechanism at the time of measurement, or the half mirror is always placed in the optical path and the light is captured by the half mirror. The structure which leads to is adopted.

Japanese Patent No. 3770206

  However, the method of Patent Document 1 has a problem that the correction accuracy decreases due to the thermal displacement of the moving mechanism itself when the moving mechanism is used. In the method of inserting the half mirror, the laser beam is attenuated by the half mirror. There are problems such as. Furthermore, since the position of the reference mark is away from the imaging unit, it is difficult to perform highly accurate correction. Furthermore, since the reference mark itself does not emit light, it is necessary to separately prepare illumination means for observing the reference mark, leading to an increase in apparatus cost.

  The present invention has been made in view of such circumstances, and provides an additive manufacturing apparatus capable of correcting the irradiation position of laser light with high accuracy at low cost.

  According to the present invention, a chamber that covers a required modeling area and is filled with an inert gas having a predetermined concentration, and an irradiation position by irradiating a predetermined position of a material powder layer formed on the modeling area with laser light. A laser beam irradiating unit that sinters the material powder, an imaging unit disposed adjacent to the modeling region, and a correcting unit that corrects the irradiation position of the laser beam, wherein the correcting unit includes the laser beam The imaging unit detects the actual irradiation position of the laser beam or the guide light having substantially the same optical axis as that when the coordinates of a predetermined point on the imaging unit are input as the irradiation position of the imaging unit, and the detected irradiation There is provided an additive manufacturing apparatus configured to correct an irradiation position of the laser beam based on a change in position with time.

  In the present invention, the irradiation position of the laser beam or the guide light having the same optical axis as the laser beam is detected using an imaging unit arranged adjacent to the modeling region, and the irradiation position of the laser beam is corrected based on the change over time. I do. According to this method, since the laser beam or the guide light is directly observed, no separate illumination means is required, and the imaging unit is disposed at a position adjacent to the modeling area, so that the laser beam or the guide light is irradiated with high resolution. A positional shift can be detected. Therefore, according to the present invention, it is possible to correct the irradiation position of the laser light with high accuracy at low cost.

Hereinafter, various embodiments of the present invention will be exemplified. The following embodiments can be combined with each other.
Preferably, the imaging unit is disposed at a plurality of locations adjacent to the modeling region and spaced apart from each other, and the correction unit is configured to change the laser based on a change with time of an irradiation position detected by each of the plurality of imaging units. It is comprised so that the irradiation position of light may be correct | amended.
Preferably, the laser light irradiation unit includes a laser light source that outputs laser light and a pair of galvano scanners that two-dimensionally scan the laser light output from the laser light source, and the imaging unit rotates the galvano scanner. The irradiation position of the laser beam or the guide light is detected in a state where the angle control signal is set to a value corresponding to the predetermined coordinate.
Preferably, the imaging unit is configured to detect an irradiation position of the laser beam or guide light before the start of additive manufacturing and during the additive manufacturing.
Preferably, the imaging unit is configured such that the laser light or the guide light is incident through a translucent plate.

It is a schematic block diagram of the additive manufacturing apparatus of one Embodiment of this invention. 3 is a perspective view of a powder layer forming apparatus 3 and a laser beam irradiation unit 13. FIG. 2 is a perspective view of a recoater head 11. FIG. 3 is a perspective view of the recoater head 11 as seen from another angle. FIG. It is explanatory drawing of the process of detecting the irradiation position of the laser beam L and the guide light G in the additive manufacturing method using the additive manufacturing apparatus of one Embodiment of this invention before the start of additive manufacturing. It is a perspective view corresponding to FIG. 5 of the powder layer forming apparatus 3 and the laser beam irradiation part 13. FIG. It is explanatory drawing of the additive manufacturing method using the additive manufacturing apparatus of one Embodiment of this invention. It is explanatory drawing of the additive manufacturing method using the additive manufacturing apparatus of one Embodiment of this invention. It is explanatory drawing of the position shift of the irradiation position of the laser beam L and the guide beam G.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Various characteristic items shown in the following embodiments can be combined with each other.

  As shown in FIGS. 1 to 2, the additive manufacturing apparatus according to the embodiment of the present invention is formed on the modeling region R and the chamber 1 that covers the required modeling region R and is filled with an inert gas having a predetermined concentration. A laser beam irradiation unit 13 is provided that irradiates a predetermined portion of the material powder layer 8 with the laser beam L to sinter the material powder at the irradiation position.

  A powder layer forming device 3 is provided in the chamber 1. The powder layer forming apparatus 3 includes a base 4 having a modeling region R, a recoater head 11 disposed on the base 4 and configured to be movable in a horizontal uniaxial direction (arrow B direction), and the recoater head 11. And elongate members 9r and 9l provided on both sides of the modeling region R along the moving direction. In the modeling area R, a modeling table 5 that is driven by the drive mechanism 31 and is movable in the vertical direction (the direction of arrow A in FIG. 1) is provided. When the additive manufacturing apparatus is used, the modeling plate 7 is disposed on the modeling table 5, and the material powder layer 8 is formed thereon. An imaging unit 41 is disposed adjacent to the modeling region R. The imaging units 41 are installed at two locations so as to face each other with the modeling region R in between. The imaging unit 41 is configured such that laser light enters through a translucent plate (not shown). The imaging unit 41 is constituted by, for example, a CCD camera, and is used for detecting the irradiation position of the laser light L or the guide light G having the same optical axis as this and correcting the deviation of the irradiation position. The translucent plate has a function of preventing the imaging unit 41 from being damaged by the laser light L or the guide light G by attenuating the laser light L or the guide light G. The translucent plate can be omitted if unnecessary.

  A powder holding wall 26 is provided so as to surround the modeling table 5, and the unsintered material powder is held in the powder holding space surrounded by the powder holding wall 26 and the modeling table 5. Below the powder holding wall 26, a powder discharge portion 27 capable of discharging the material powder in the powder holding space is provided. The resulting material powder is discharged from the powder discharge unit 27, and the discharged material powder is guided to the shooter 29 by the shooter guide 28 and is accommodated in the bucket 30 through the shooter 29.

  2 to 4, the recoater head 11 is provided with a material container 11a, a material supply unit 11b provided on the top surface of the material container 11a, a bottom surface of the material container 11a, and a material container. The material discharge part 11c which discharges | emits the material powder in the part 11a is provided. The material discharging part 11c has a slit shape extending in the horizontal one-axis direction (arrow C direction) orthogonal to the moving direction of the recoater head 11 (arrow B direction). On both side surfaces of the recoater head 11, squeezing blades 11fb and 11rb for flattening the material powder discharged from the material discharging portion 11c to form the material powder layer 8 are provided. Further, on both side surfaces of the recoater head 11, fume suction portions 11 fs and 11 rs for sucking fume generated during sintering of the material powder are provided. The fume suction portions 11fs and 11rs are provided along a horizontal one-axis direction (arrow C direction) orthogonal to the moving direction (arrow B direction) of the recoater head 11. The material powder is, for example, metal powder (eg, iron powder), and has a spherical shape with an average particle diameter of 20 μm, for example.

  The elongated members 9r, 9l are each provided with an opening along the moving direction of the recoater head 11 (the direction of arrow B). Since one of these openings is used as an inert gas supply port and the other is used as an inert gas discharge port, an inert gas can flow on the modeling region R in the direction of arrow C. Fumes generated in R are easily discharged along the flow of the inert gas. In this specification, “inert gas” is a gas that does not substantially react with the material powder, and examples thereof include nitrogen gas, argon gas, and helium gas.

  A laser beam irradiation unit 13 is provided above the chamber 1. As shown in FIG. 2, the laser beam irradiation unit 13 includes a laser light source 42 that outputs laser light L, a pair of galvano scanners 43a and 43b that two-dimensionally scan the laser light L output from the laser light source 42, and a laser. And a condensing lens 44 that condenses the light L. The laser light source 42 can also output guide light G having substantially the same optical axis as the laser light L. The guide light G is visible laser light such as red laser light. The galvano scanner (X-axis scanner) 43a scans the laser beam L and the guide beam G in the direction of the arrow B (X-axis direction), and the galvano scanner (Y-axis scanner) 43b scans the laser beam L and the guide beam G with the arrow C Scan in the direction (Y-axis direction). Since the rotation angles of the scanners 43a and 43b are controlled in accordance with the magnitudes of the rotation angle control signals, the lasers are moved to desired positions by changing the magnitudes of the rotation angle control signals input to the scanners 43a and 43b. The irradiation positions of the light L and the guide light G can be moved. An example of the condenser lens 44 is an fθ lens.

The laser light L and the guide light G that have passed through the condensing lens 44 pass through the window 1 a provided in the chamber 1 and are irradiated onto the material powder layer 8 formed in the modeling region R. The type of the laser beam L is not limited as long as the material powder can be sintered, and examples thereof include a CO ₂ laser, a fiber laser, and a YAG laser. The window 1a is formed of a material that can transmit the laser light L. For example, when the laser beam L is a fiber laser or a YAG laser, the window 1a can be made of quartz glass.

  A fume diffusion portion 17 is provided on the upper surface of the chamber 1 so as to cover the window 1a. The fume diffusing unit 17 includes a cylindrical casing 17a and a cylindrical diffusing member 17c disposed in the casing 17a. An inert gas supply space 17d is provided between the housing 17a and the diffusion member 17c. An opening 17b is provided on the bottom surface of the housing 17a inside the diffusion member 17c. The diffusion member 17c is provided with a large number of pores 17e, and the clean inert gas supplied to the inert gas supply space 17d fills the clean space 17f through the pores 17e. And the clean inert gas with which the clean space 17f was filled is ejected toward the downward direction of the fume spreading | diffusion part 17 through the opening part 17b.

  Next, an inert gas supply system to the chamber 1 and a fume discharge system from the chamber 1 will be described.

  An inert gas supply device 15 and a fume collector 19 are connected to the inert gas supply system to the chamber 1. The inert gas supply device 15 has a function of supplying an inert gas, and is, for example, a gas cylinder of an inert gas. The fume collector 19 has duct boxes 21 and 23 on the upstream side and the downstream side thereof. The gas discharged from the chamber 1 (inert gas including fumes) is sent to the fume collector 19 through the duct box 21, and the inert gas from which fumes have been removed in the fume collector 19 is sent to the chamber 1 through the duct box 23. . With such a configuration, the inert gas can be reused.

  As shown in FIG. 1, the inert gas supply system is connected to the upper supply port 1b of the chamber 1, the inert gas supply space 17d of the fume diffusing section 17, and the elongated member 9r. An inert gas is filled into the modeling space 1d of the chamber 1 through the upper supply port 1b. The inert gas supplied into the elongated member 9r is discharged onto the modeling region R through the opening.

  In the present embodiment, the inert gas from the fume collector 19 is sent to the upper supply port 1b, and the inert gas from the inert gas supply device 15 is sent to the inert gas supply space 17d and the elongated member 9r. Has been. Although there is a possibility that fumes that could not be removed remain in the inert gas from the fume collector 19, in the configuration of the present embodiment, the space in which the inert gas from the fume collector 19 requires particularly high purity is required. Since it is not supplied to the (clean space 17f and the space near the modeling region R), the influence of residual fume can be minimized.

  As shown in FIG. 1, the fume discharge system from the chamber 1 is connected to the upper discharge port 1c of the chamber 1, the fume suction parts 11fs and 11rs of the recoater head 11, and the elongated member 9l. As the inert gas containing fumes in the modeling space 1d of the chamber 1 is discharged through the upper discharge port 1c, a flow of inert gas from the upper supply port 1b toward the upper discharge port 1c is formed in the modeling space 1d. Is done. The fume suction units 11 fs and 11 rs of the recoater head 11 can suck the fumes generated in the modeling region R when the recoater head 11 passes over the modeling region R. In addition, an inert gas containing fumes is discharged out of the chamber 1 through the opening of the elongated member 9l. The fume discharge system is connected to the fume collector 19 through the duct box 21, and the inert gas after the fume is removed in the fume collector 19 is reused.

  Next, the layered manufacturing method using the above-described layered manufacturing apparatus will be described with reference to FIGS. 1 and 5 to 9.

  First, before the start of layered modeling, the coordinates of the point A on one imaging unit 41 are input as the irradiation position of the laser light L. Specifically, a value corresponding to the coordinates of the point A is input as a rotation angle control signal for the scanners 43a and 43b. As a result, as shown in FIGS. 5 to 6, the scanners 43 a and 43 b rotate at a predetermined rotation angle, and the irradiation positions of the laser light L and the guide light G are moved to a predetermined point A <b> 1 on the imaging unit 41. . The coordinates of the point A1 are acquired by detecting the laser light L or the guide light G with the imaging unit 41. Similarly, the coordinates of the point B on the other imaging unit 41 are input as the irradiation position of the laser beam L, the irradiation positions of the laser beam L and the guide beam G are moved to the point B1, and the imaging unit 41 uses the laser beam L. Alternatively, the coordinates of the point B1 are acquired by detecting the guide light G. The coordinates of the points A1 and B1 are the coordinates of the actual irradiation position and preferably exactly coincide with the coordinates of the points A and B as input coordinates, but may be slightly shifted. Points A1 and B1 are shown in FIG.

Next, additive manufacturing is started. First, the height of the modeling table 5 is adjusted to an appropriate position with the modeling plate 7 placed on the modeling table 5. In this state, the first layer on the modeling plate 7 is moved by moving the recoater head 11 filled with the material powder in the material container 11a from the left side to the right side of the modeling region R in the direction of arrow B in FIG. The material powder layer 8 is formed.
Next, by irradiating a laser beam L to a predetermined site in the material powder layer 8 to sinter the laser beam irradiated site of the material powder layer 8, as shown in FIG. A binder layer 81f is obtained.
Next, the height of the modeling table 5 is lowered by one layer of the material powder layer 8, and the recoater head 11 is moved from the right side to the left side of the modeling region R, whereby the second layer material is formed on the sintered layer 81f. A powder layer 8 is formed.
Next, as shown in FIG. 8, the second layer is sintered by irradiating a predetermined portion in the material powder layer 8 with the laser beam L to sinter the laser beam irradiated portion of the material powder layer 8. A bonded layer 82f is obtained.
By repeating the above steps, the third sintered layer 83f, the fourth sintered layer 84f, and the fifth and subsequent sintered layers are formed. Adjacent sintered layers are firmly fixed to each other.

  After a predetermined number (for example, 10 layers) of sintered layers are formed, the coordinates of points A and B are input again as the irradiation position of the laser beam L. The irradiation positions of the laser beam L and the guide beam G at this time are moved to points A2 and B2. The points A2 and B2 deviate from the corresponding points A1 and B1 at the start of the layered modeling when the layered modeling apparatus is distorted by the thermal displacement. As the types of deviation, as shown in FIGS. 9B to 9F, there are an X-direction deviation, a Y-direction deviation, a rotational deviation, and a combination thereof. Note that this shift is detected by the imaging unit 41 directly receiving the laser light L or the guide light G, so that the resolution of the imaging unit 41 can be utilized to the maximum. Therefore, the correction accuracy can be improved as compared with the method described in Patent Document 1.

  The deviation from the start of additive manufacturing can be corrected by calculating the X deviation amount, the Y deviation amount, and the rotational deviation amount θ and substituting them into the following conversion equation (1). For example, when the coordinates of the point A2 are (X2, Y2), the coordinates (X1, Y1) obtained by conversion by the conversion formula (1) substantially match the point A1. And the shift | offset | difference of the coordinate by a thermal displacement can be correct | amended by converting the coordinate of each point in the modeling area | region R based on conversion formula (1). Such correction can be performed by, for example, a control unit that controls the operation of the scanners 43a and 43b. This control unit corresponds to “correction means” in the claims.

  Next, a predetermined number (for example, 10 layers) of sintered layers is further formed in a state where the thermal correction is made by the conversion formula (1), and thereafter, points A and B are again set as the irradiation positions of the laser beam L. Enter the coordinates of. The irradiation positions of the laser beam L and the guide beam G at this time are moved to points A3 and B3. Since the points A3 and B3 are deviated from the corresponding points A1 and B1 at the start of the layered modeling as a result of the thermal displacement, the deviation is calculated in the same manner as described above, and the calculated value is used in the modeling region R. By converting the coordinates of each point based on the conversion formula (1), it is possible to correct a shift in coordinates due to thermal displacement.

  Thereafter, it is possible to correct the deviation by the same method every time a predetermined number of sintered layers are formed until the additive manufacturing is completed.

  After the completion of the layered modeling, the molded product can be obtained by discharging the unsintered material powder through the powder discharging unit 27.

The present invention can also be implemented in the following modes.
In the above embodiment, the imaging units 41 are provided at two locations for correcting the rotational deviation. However, when the rotational deviation is not corrected, the imaging unit 41 may be provided at one location.
In the above embodiment, the deviation from the points A1 and B1 at the start of additive manufacturing is calculated. However, the position of the reference point for calculating the deviation is limited to the points A1 and B1 at the start of additive manufacturing. For example, the point at the time after forming one or more sintered layers from the start of additive manufacturing may be used as a reference. That is, the deviation may be calculated based on the temporal change of the irradiation position of the laser light L or the guide light G when the predetermined coordinates are input.
In the above embodiment, the pair of galvano scanners 43a and 43b is used as the scanning unit for the laser beam L. However, the laser beam L may be two-dimensionally scanned by another unit.
A processing head having a spindle may be provided. In this case, it is possible to cut the shaped article every time a predetermined number (for example, 10 layers) of sintered layers is formed. The timing for performing the cutting process may be the same as or different from the timing for correcting the thermal displacement.

1: chamber, 3: powder layer forming device, 5: modeling table, 8: material powder layer, 11: recoater head, 17: fume diffusing section, 26: powder holding wall, 27: powder discharging section, 28: Shooter guide, 29: Shooter, 30: Bucket, 31: Drive mechanism, 32: Powder holding space, 33: Upper wiper, 34: Dust tray, 35: Drive mechanism partition, 36: Lower wiper, 41: Imaging unit 41a: translucent plate, 41b: imaging unit, 42: laser light source, 43a, 43b: galvano scanner, 44: condenser lens, L: laser light

Claims (5)

A chamber that covers the required modeling area and is filled with an inert gas at a predetermined concentration;
A laser beam irradiation unit that irradiates a predetermined portion of the material powder layer formed on the modeling region with laser beam to sinter the material powder at the irradiation position;
First and second imaging units arranged adjacent to the modeling area;
Compensating means for correcting the irradiation position of the laser light,
The correction means is an actual irradiation position of the laser light or guide light having substantially the same optical axis as that when the coordinates of a predetermined point on the first and second imaging units are input as the irradiation position of the laser light. Is detected by the first and second imaging units, and the irradiation position of the laser beam is corrected based on the detected temporal change of the irradiation position,
In the additive manufacturing apparatus configured to be capable of scanning the laser beam in the X-axis direction and the Y-axis direction, the laser beam irradiation unit ,
The first and second imaging units are provided on both sides of the modeling area along the moving direction of a recoater head that reciprocates in the horizontal one axis direction parallel to the X axis direction on the modeling area. It is a position excluding the position where the elongated member used as the supply port or the discharge port of the active gas is provided, so as to be at an approximately middle position between the elongated members on both sides and along the moving direction. layered manufacturing apparatus characterized by being arranged so as to face each other across the said shaping region. The additive manufacturing apparatus according to claim 1, wherein the correction unit is configured to correct the irradiation position of the laser beam based on a change with time of the irradiation position detected by each of the plurality of imaging units. The laser light irradiation unit includes a laser light source that outputs laser light, and a pair of galvano scanners that two-dimensionally scan the laser light output from the laser light source,
The said 1st and 2nd imaging part is comprised so that the irradiation position of the said laser beam or guide light may be detected in the state which made the rotation angle control signal of the said galvano scanner the value corresponding to the said predetermined coordinate. The additive manufacturing apparatus according to claim 1. The said 1st and 2nd imaging part is comprised so that the irradiation position of the said laser beam or guide light may be detected before the lamination modeling start and during the lamination modeling. The additive manufacturing apparatus described. The additive manufacturing according to any one of claims 1 to 4, wherein the first and second imaging units are configured such that the laser light or the guide light is incident through a translucent plate. apparatus.