JP6477428B2 - Control method of additive manufacturing apparatus - Google Patents

Description

  The present invention relates to an additive manufacturing apparatus.

  In recent years, a layered modeling apparatus that produces a three-dimensional layered object by irradiating a powder made of an inorganic material or an organic material with a light beam and sintering or melting and solidifying has been attracting attention. Specifically, a process of forming a powder layer by spreading powder on a surface plate, and a process of forming a hardened layer by irradiating a predetermined region of the powder layer with a light beam and sintering or melting and solidifying it. And repeat. Thereby, many hardened layers can be laminated and integrated to produce a three-dimensional shaped object.

  Patent Document 1 describes that when forming a small shaped object, a powder material is sintered with a laser beam to form a support wall, thereby forming a work area smaller than the maximum work area.

JP 2011-251529 A

  However, in the modeling method of Patent Document 1, the powder is prepared with a squeegee, the modeled objects are stacked, and the support wall is also stacked in accordance with the stacking height. It is necessary to re-form the support wall. Therefore, the modeling method of the cited document 1 has the problem that the consumption of the powder which forms a support wall, and modeling time increase.

  Also, when forming the support wall with a plate, it is necessary to change the height of the plate according to the lamination of the powder, but since the workpiece foundation also laminates the powder, the workpiece foundation is laminated under the same conditions as the modeling part, If the height of the support wall is changed, there is a problem that the molding time increases.

  In view of the above, an object of the present invention is to provide an additive manufacturing apparatus that can reduce modeling time.

  The additive manufacturing apparatus of the present invention supplies and laminates powder in a modeling tank, solidifies the laminated powder layer in a desired region, and forms a desired shape and a workpiece base that serves as the foundation of the modeling portion. And forming a collapsing prevention wall in the modeling tank, which raises the height of the wall together with the lamination of powder and prevents the collapsing of the laminated powder, and the work base of the collapsing prevention wall The rising speed up to the height of the upper end of the was made faster than the rising speed at the height of the modeling part.

  According to the additive manufacturing apparatus of the present invention, it is possible to reduce the time required for raising the collapsing prevention wall.

It is typical sectional drawing which shows the outline | summary of the additive manufacturing apparatus which concerns on this Embodiment. It is typical sectional drawing which shows arrangement | positioning of the collapsing prevention wall in the additive manufacturing apparatus which concerns on this Embodiment. It is a typical top view which shows the outline | summary of the additive manufacturing apparatus which concerns on this Embodiment. It is a flowchart which shows the outline of operation | movement of the additive manufacturing apparatus which concerns on this Embodiment. It is a flowchart explaining the workpiece base filling process of the additive manufacturing apparatus which concerns on this Embodiment. It is a flowchart explaining the process of laminating | stacking the modeling part of the additive manufacturing apparatus which concerns on this Embodiment.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiment. In addition, for clarity of explanation, the following description and drawings are simplified as appropriate.

  In the present embodiment, the overall configuration of the additive manufacturing apparatus will be described first, then the part where the collapse prevention wall is provided will be described, and then the configuration of the collapse prevention wall, which is a feature of the present embodiment, will be described.

(This embodiment)
First, the layered manufacturing apparatus according to the present embodiment will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing an overview of the additive manufacturing apparatus according to the present embodiment.
As shown in FIG. 1, the additive manufacturing apparatus according to the present embodiment includes a base 1, a surface plate 2, a modeling tank 3, a modeling tank support unit 4, a modeling tank drive unit 5, a support column 6, a support unit 7, and a laser scanner. 8, an optical fiber 9, a laser oscillator 10, a squeegee 11, a basket 12, a powder distributor 13, a powder supply unit 14, fall prevention walls 201 and 202, and a fall prevention wall driving device 203.

  The base 1 is a table for fixing the surface plate 2 and the column 6. The base 1 is installed on the floor so that the upper surface on which the surface plate 2 is placed is horizontal.

  The surface plate 2 is placed and fixed on the horizontal upper surface of the base 1. The upper surface of the surface plate 2 is also horizontal, and powder is spread on the upper surface of the surface plate 2 to form a shaped object 50. In the example of FIG. 1, the surface plate 2 is a quadrangular columnar member. As shown in FIG. 1, a flange-like convex portion 2 a that protrudes in the horizontal direction is formed on the entire periphery of the upper surface of the surface plate 2. Since the outer peripheral surface of the convex portion 2 a is in contact with the inner surface of the modeling tank 3 throughout, the laminated powder 51 can be held in the space surrounded by the upper surface of the surface plate 2 and the inner surface of the modeling tank 3. it can. Here, by providing a seal member (not shown) made of felt, for example, on the outer peripheral surface of the convex portion 2 a that is in contact with the inner side surface of the modeling tank 3, the holding power of the laminated powder 51 can be increased.

  The modeling tank 3 is a cylindrical member that holds the powder spread on the upper surface of the surface plate 2 from the side surface. In the example of FIG. 1, since the surface plate 2 has a quadrangular prism shape, the modeling tank 3 is a square pipe having a flange portion 3a at the upper end. The modeling tank 3 is made of, for example, a stainless steel plate having a thickness of about 1 to 6 mm (preferably about 3 to 5 mm) and is lightweight. A powder layer is formed on the upper opening end 3b of the modeling tank 3, and a hardened layer is formed by irradiating the powder layer with a laser beam LB. The shape of the upper opening end 3b is, for example, 600 mm × 600 mm.

  The modeling tank 3 is installed so as to be movable in the vertical direction (z-axis direction). Each time a hardened layer is formed, the modeling tank 3 is raised by a certain amount relative to the surface plate 2 to form a modeled object 50. Here, in the additive manufacturing apparatus according to the present embodiment, only the constant-weight and lightweight modeling tank 3 may be raised. Therefore, the powder layer can be formed with high accuracy every time. As a result, the molded article 50 can be formed with high accuracy.

The modeling tank support part 4 is a support member that supports the lower surface of the flange part 3a at three points so that the upper surface of the flange part 3a of the modeling tank 3 is horizontal.
The modeling tank support part 4 is connected to a connecting part 5c of a modeling tank drive unit 5 that moves the modeling tank 3 in the vertical direction (z-axis direction).

  The modeling tank drive unit 5 is a drive mechanism for moving the modeling tank 3 in the vertical direction (z-axis direction). The modeling tank driving unit 5 includes a motor 5a, a ball screw 5b, and a connecting portion 5c. When the motor 5a is driven, the ball screw 5b extending in the z-axis direction rotates. When the ball screw 5b rotates, the connecting portion 5c moves in the vertical direction (z-axis direction) along the ball screw 5b. Since the modeling tank support part 4 which supports the modeling tank 3 is connected with the connection part 5c as above-mentioned, the modeling tank 3 becomes movable by the modeling tank drive part 5 to an up-down direction (z-axis direction). The drive source of the modeling tank drive unit 5 is not limited to a motor, and a hydraulic cylinder or the like may be used.

  Here, the modeling tank drive unit 5 is fixed to an upper portion of a support column 6 that is erected substantially vertically (that is, in a vertical direction) from the base 1. As described above, in the additive manufacturing apparatus according to the present embodiment, the modeling tank driving unit 5 is installed outside the modeling tank 3, and thus has excellent maintainability.

The laser scanner 8 irradiates the powder layer formed on the upper opening end 3 b of the modeling tank 3 with the laser beam LB. The laser scanner 8 has a lens and a mirror (not shown). Therefore, as shown in FIG. 1, the laser scanner 8 can focus the laser beam LB on the powder layer regardless of the position on the horizontal plane (xy plane) in the powder layer.
Here, the laser beam LB is generated in the laser oscillator 10 and introduced into the laser scanner 8 via the optical fiber 9.

  The laser scanner 8 is fixed to the flange portion 3 a of the modeling tank 3 through the support portion 7. Therefore, the distance between the laser scanner 8 and the powder layer that is the irradiation target of the laser beam LB can be kept constant. Therefore, the additive manufacturing apparatus according to the present embodiment can manufacture the modeled object 50 with high accuracy.

  The squeegee 11 includes a first squeegee 11a and a second squeegee 11b. Both the first squeegee 11a and the second squeegee 11b extend in the y-axis direction. Further, the squeegee 11 can slide in the x-axis direction from the one flange portion 3 a to the opposite flange portion 3 a via the upper opening end 3 b of the modeling tank 3.

  As shown in FIG. 1, the powder is supplied between the first squeegee 11a and the second squeegee 11b on the flange 3a on the negative side of the x-axis. Here, the powder for forming the powder layer for 2 times is supplied. That is, the squeegee 11 slides from the x-axis minus side flange portion 3 a to the x-axis plus side flange portion 3 a, so that one powder layer is formed at the upper opening end 3 b of the modeling tank 3. As indicated by a broken line in FIG. 1, while the powder layer is irradiated with the laser beam LB and the hardened layer is formed, the squeegee 11 stands by on the flange 3a on the x-axis plus side. Then, the squeegee 11 slides from the x-axis plus side flange portion 3 a to the x-axis minus side flange portion 3 a, whereby another powder layer is formed on the upper opening end 3 b of the modeling tank 3.

  For example, when the formation region of the hardened layer is narrow, the hardened layer formation region is covered without sliding the squeegee 11 from the x-axis minus side flange portion 3a to the x-axis plus side flange portion 3a as much as possible. Above, you may stop the slide in the middle. The amount of powder for forming the powder layer can be saved and the time can be shortened.

The basket 12 and the powder distributor 13 are for uniformly distributing the powder dropped from the powder supply unit 14 in the longitudinal direction of the squeegee 11.
An opening having a length (y-axis direction) that is narrower than the distance (x-axis direction) between the first squeegee 11 a and the second squeegee 11 b (x-axis direction) and is approximately the same as the powder injection region of the squeegee 11 is formed on the lower surface of the flange 12. Is formed. However, the powder is dropped from the powder supply unit 14 to the end of the ridge 12 where no opening is formed.

  The powder distributor 13 is a plate-like member having the same shape as the cross-sectional shape of the groove of the ridge 12. The powder distributor 13 can be slid in the y-axis direction by a drive mechanism (not shown). Here, in FIG. 1, the powder distributor 13 is drawn away from the basket 12 for easy understanding. However, in practice, the powder distributor 13 slides in contact with both sides of the groove of the ridge 12 without any gap. When the powder distributor 13 slides from one end to the other end where the powder is dropped in the basket 12, the powder is uniformly distributed in the longitudinal direction of the squeegee 11 through the opening of the basket 12.

  For example, when the formation area of the hardened layer is narrow, the powder distributor 13 is not slid from one end to the other end of the basket 12 as much as possible. May be. The amount of powder for forming the powder layer can be saved and the time can be shortened.

  The powder supply unit 14 is a small tank in which powder is stored. The powder is made of an inorganic material (metal or ceramic) or an organic material (plastic). Preferably, iron powder having an average particle size of about 20 μm is used.

The collapsing prevention walls 201 and 202 are walls that rise with the lamination of powders and prevent the laminated powders from collapsing.
The collapsing prevention wall driving device 203 is a device that is provided in or on the surface plate 2 and controls and moves the collapsing preventing walls 201 and 202 on the horizontal plane (XY position).

  Next, the site | part which provides a collapsing prevention wall is demonstrated. FIG. 2 is a schematic cross-sectional view showing the arrangement of the collapse prevention walls in the additive manufacturing apparatus according to the present embodiment. As shown in FIG. 2, in the present embodiment, a collapse prevention wall is provided in an area defined by the surface plate 2 and the modeling tank 3 of the layered modeling apparatus. FIG. 3 is a schematic top view showing an outline of the additive manufacturing apparatus according to the present embodiment.

  As shown in FIG. 3, the additive manufacturing apparatus is provided with collapse prevention walls 201 and 202 in an area defined by the surface plate 2 and the modeling tank 3 (that is, an area indicated by the upper opening end 3 b).

  The collapsing prevention walls 201 and 202 can move in the horizontal direction within an area defined by the surface plate 2 and the modeling tank 3. Specifically, the collapsing prevention wall 201 is movable in the X direction, and the collapsing prevention wall 202 is movable in the Y direction. A work area smaller than the maximum work area can be defined by the surface plate 2, the modeling tank 3, and the collapsing prevention walls 201 and 202. The collapsing prevention walls 201 and 202 can be moved in the XYZ triaxial directions by a hydraulic control device built in the surface plate 2. The movement of the collapsing prevention walls 201 and 202 in the Z-axis direction (vertical direction) will be described later.

Next, the operation of the additive manufacturing apparatus according to the present embodiment will be described with reference to FIGS. First, the overall operation will be described with reference to FIG. 4, then the details of the step of filling the workpiece base will be described with reference to FIG. 5, and then the region of the modeling part will be stacked with reference to FIG. 6. Details will be described.
FIG. 4 is a flowchart showing an outline of the operation of the additive manufacturing apparatus according to the present embodiment.

First, in step S401, the additive manufacturing apparatus acquires information on the opening control of the squeegees 11a and 11b (that is, information on the powder material supply area in FIG. 3), and proceeds to step S402.
In step S402, the additive manufacturing apparatus determines positions (XY positions) of the collapsing prevention walls 201 and 202 on the horizontal plane based on the acquired information on the powder material supply region, and the process proceeds to step S403. Specifically, in step S402, as shown in FIG. 2, the position where the squeegee margin is added to the powder material supply region is set as the positions of the collapse prevention walls 201 and 202.

In step S403, the additive manufacturing apparatus raises the collapsing prevention walls 201 and 202 at a faster speed than the additive manufacturing process described later (in step S404). Then, after the collapsing prevention walls 201 and 202 are completed (and the work base area is filled), the process proceeds to step S404.
In step S404, the region of the modeling part is filled with powder, and the collapsing prevention walls 201 and 202 are raised at a slower speed than the work base filling process in step S403 described above. That is, in the stacking of the modeling parts, the collapsing prevention walls 201 and 202 slide with the powder material as the collapsing prevention walls 201 and 202 rise. Therefore, it is necessary to suppress the deterioration of accuracy. Therefore, in the additive manufacturing process, the collapsing prevention walls 201 and 202 are raised at a slower speed than the work base filling process. And in step S404, a series of processings are ended by completing the lamination of the modeling parts.

Next, details of the process of filling the workpiece base will be described. FIG. 5 is a flowchart for explaining a work base filling process of the additive manufacturing apparatus according to the present embodiment.
First, in step S501, it is determined whether or not to start the process of filling the powder material. And when starting the process of filling a powder material, it progresses to step S502, and when not starting the process of filling a powder material, step S501 is repeated. Specifically, when a signal related to the start of the process of filling the powder material is detected, the process of filling the powder material is started, and the process proceeds to step S502. If the signal related to the start of the process of filling the powder material is not detected, the process of filling the powder material is not started and step S501 is repeated.

The signal relating to the start of the process of filling the powder material may be any of the following.
(1) An operation (or operation preparation) signal of the powder supply unit 14 in FIG.
(2) A signal generated by turning on a work start switch (not shown) when an operator inputs powder material.
(3) When using “another powder material supply means (not shown)” that can supply a mass (or a predetermined amount) of powder instead of a squeegee, the operation of another powder material supply means (or Ready for operation) signal.

  In step S502, the collapsing prevention walls 201 and 202 are raised at a speed faster than the rising speed in the additive manufacturing process, and the process proceeds to step S503. Specifically, the ascending speed in the layered manufacturing process satisfies the conditional expression of the ascending speed ≧ the height of two layers / the squeegee return path moving time. In step S502, the collapsing prevention walls 201 and 202 are raised at a speed faster than the rising speed in the additive manufacturing process that satisfies this conditional expression.

  In step S503, it is determined whether or not the heights of the collapse prevention walls 201 and 202 have reached the height of the upper end of the workpiece base. If the heights of the collapsing prevention walls 201 and 202 have reached the height of the upper end of the workpiece base, the process proceeds to step S504. If the heights of the collapsing prevention walls 201 and 202 have not reached the height of the upper end of the workpiece base, the process returns to step S502.

In step S504, the rising of the collapsing prevention walls 201 and 202 is stopped, and the setting of the climbing speed of the collapsing prevention walls 201 and 202 is returned to the normal climbing speed (that is, the climbing speed when stacking the modeling parts in the layered modeling process). The process proceeds to step S505.
In step S505, the work base region is filled with the powder material, and the process proceeds to step S506.

In step S506, it is determined whether or not filling of the powder material into the work base region is completed. Specifically, it is determined whether or not the filling of the powder material in the work base region is completed based on the following signals.
(1) A signal based on comparison between the shape data up to the upper end of the “work base” and the accumulated stacking height, or the number of stacking, etc. (2) A signal generated by turning on a work completion switch (not shown) by an operator.
(3) Stop signal of another powder material supply means.
(4) A signal from an optical sensor provided in the modeling tank.
If the work base area is not completely filled with the powder material, the process returns to step S505. When the filling of the powder material into the work base region is completed, the work base filling process (step 603 in FIG. 4) is terminated.

Next, the detail of the process of laminating | stacking the area | region of a modeling part is demonstrated. FIG. 6 is a flowchart for explaining a process of laminating the modeling parts of the additive manufacturing apparatus according to the present embodiment.
First, in step S601, it is determined whether or not the squeegee has been reversed (the return path has been stacked). If the squeegee is not reversed, step S601 is repeated. If the squeegee is reversed, the process proceeds to step S602.

In step S602, the collapsing prevention walls 201 and 202 are raised by the height of two layers (that is, a reciprocating stacked portion), and the process proceeds to step S603.
In step S <b> 603, it is detected whether the stacking upper limit height (for example, the workpiece height) has been reached from the comparison between the shape data of the modeled product and the cumulative stacking height, or the number of stacking times. If the stacking upper limit height has not been reached, the process returns to step S601. Moreover, when the lamination | stacking upper limit height is reached | attained, a lamination modeling process (step 604 of FIG. 4) is complete | finished.

  With the above operation, the additive manufacturing apparatus according to the present embodiment increases the rising speed of the collapsing prevention walls 201 and 202 when the workpiece base is filled with the material powder, and maintains the precision of the additive manufacturing in the additive manufacturing process. The collapsing prevention walls 201 and 202 are raised at a speed capable of being

  Thus, according to the additive manufacturing apparatus of the present embodiment, the collapsing prevention wall is raised to the height of the upper end of the work base at a rising speed faster than the climbing speed at the height of the modeling part. It is possible to reduce the time required for the increase in the modeling time.

Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention. For example, in the work base filling process, raising the collapsing prevention walls 201 and 202 at a faster speed than the additive manufacturing process may be applied to the following cases.
(1) Up to the upper end of the workpiece base, the speed is more important than the accuracy of the thickness of the stack, and the operation (stacking) speed of the squeegee is increased.
(2) Instead of a squeegee, an operator inputs a powder material.
(3) Another powder supply means capable of feeding a mass of material is used.

2 Surface plate 3 Modeling tank 3b Upper open end 201, 202 Collapse prevention wall 203 Collapse prevention wall drive device

Claims (1)

Shaping the powder was fed and stacked in the vessel, a stacked layer of powder solidified in a desired region, and shaping part of the desired shape, the lamination modeling apparatus for forming a workpiece foundation as a foundation of the shaped portion A control method ,
The additive manufacturing apparatus includes a collapse prevention wall in the modeling tank that increases the height of the wall together with the lamination of powder, and prevents the collapse of the laminated powder.
The method for controlling an additive manufacturing apparatus, wherein the rising speed of the collapsing prevention wall to the height of the upper end of the workpiece base is faster than the rising speed at the height of the modeling part.

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