JP6850945B2 - Powder bed fusion bonding equipment - Google Patents

Description

The present invention relates to a powder bed fusion coupling device that forms a three-dimensional model by selectively heating and solidifying a powder material with a laser beam while depositing the powder material in layers.

In the powder bed fusion coupling device, in order to prevent warpage and distortion of the modeled object, it is required to keep the surface of the powder laminated on the modeled object at a uniform temperature during irradiation with the laser beam.

For this reason, in the conventional powder bed fusion coupling device, the temperature distribution of the modeling container is measured by an infrared radiation thermometer or the like, and the surrounding heating means is controlled based on the measurement result of the temperature distribution to keep the temperature distribution constant. I'm keeping it.

Japanese Unexamined Patent Publication No. 2011-21218 Japanese Unexamined Patent Publication No. 2007-223192

In order to measure a more detailed temperature distribution, it is preferable to use an infrared camera capable of measuring the temperature distribution in two dimensions.

However, in the case of a small powder bed fusion coupling device whose size of the modeling container is, for example, 150 mm square, the installation space of the device is limited. Therefore, when the laser light optical system is installed, an infrared camera is installed on the modeling container. It is difficult to do.

Therefore, in the conventional powder bed fusion coupling device, the temperature distribution of the modeling container is measured after removing the optical system of the laser beam and replacing it with an infrared camera in the adjustment process for setting the conditions prior to modeling. , Complicated preparatory work is required.

In addition, there is no way to know whether the temperature of the surface of the modeling container is kept uniform while irradiating the laser beam. The operator had to make an empirical judgment.

Therefore, an object of the present invention is to provide a powder bed fusion coupling device capable of measuring a detailed temperature distribution on the surface of a modeling container without removing the optical system.

According to one aspect of the following disclosure, a modeling container that houses a modeled object together with a thin layer of the powder material, a laser light source that generates a laser beam that irradiates the thin layer of the powder material, and the modeling container are housed. A chamber, a laser window provided on the upper surface of the chamber, an optical scanning element for irradiating a thin layer of the powder material with the laser beam to scan through the laser window, and an optical scanning element arranged adjacent to the optical scanning element. Provided is a powder bed fusion bonding apparatus including an infrared camera that captures a temperature distribution of a thin layer of a powder material on the surface of the modeling container through the laser window.

According to the powder bed fusion coupling device of the above viewpoint, it is possible to take an image from above the modeling container with an infrared camera, and it is possible to obtain a detailed temperature distribution on the surface of the modeling container without removing the optical system.

It is a figure which shows the structure of the powder bed melt coupling apparatus which is an embodiment of this invention. FIG. 2 is a block diagram showing a laser beam emitting portion of the powder bed fusion bonding apparatus according to the embodiment. It is a figure which shows the chamber and the optical system accommodating part of the powder bed melt coupling apparatus of FIG. It is a figure which shows the arrangement relationship of the modeling container, an optical scanning element, and an infrared camera. It is a figure which shows the field of view of an optical scanning element and an infrared camera. It is a flowchart of the adjustment process by the powder bed melt coupling apparatus of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(1) Configuration of Powder Bed Melt Coupling Device The powder bed melt coupling device 10 according to the embodiment of the present invention includes a laser beam emitting unit, a modeling unit, and a control unit.

FIG. 1A is a top view showing the configuration of the modeling portion 101 in the powder bed fusion bonding device 10 of the embodiment. Note that FIG. 1A does not show the laser beam emitting unit and the control device. FIG. 1B is a cross-sectional view taken along the line I-I of FIG. 1A, which shows a laser beam emitting portion 102 arranged above the modeling portion 101 in addition to the modeling portion 101.

(A) Structure of the modeling unit As shown in FIGS. 1 (a) and 1 (b), the modeling unit 101 includes a modeling container 11 for which modeling is performed by irradiation with a laser beam, and a first container installed on both sides thereof. The powder material storage container 12a and the second powder material storage container 12b are provided.

The area surrounded by the inner wall of the modeling container 11 is the modeling area 11a, and the area surrounded by the powder material storage containers 12a and 12b is the storage area of the powder material 15.

Of these, the modeling container 11 is a container in which a three-dimensional model is produced, and can be, for example, a tubular container having a square planar shape.

In the present specification, the center of the modeling container 11 means the center of the planar shape (modeling region) of the container that appears when the modeling container 11 is viewed from above.

A part table 13a is provided at the bottom of the modeling container 11. A thin layer 15a of the powder material is formed on the part table 13a, and the thin layer 15a of the powder material is sintered or melted by irradiation with a laser beam to form a solidified layer 15b.

A threaded support shaft 13b is attached to the part table 13a, and the support shaft 13b is connected to a drive device (not shown). By operating this drive device, the part table 13a moves in the vertical direction.

Then, the part table 13a is moved downward and the solidified layers 15b are sequentially laminated to produce a three-dimensional model.

In the small powder bed fusion bonding device 10, the width and depth of the modeling container 11 can be set to, for example, about 150 mm × 150 mm.

In the first and second powder material storage containers 12a and 12b, the powder material 15 is stored on the feed table 14a, respectively.

A support shaft 14b is attached to each of the feed tables 14a, and the feed table 14a is moved up and down by a driving device (not shown).

Then, the powder material 15 is supplied by moving the feed table 14a upward.

A recorder 16 is provided on the modeling container 11 and the first and second powder material containers 12a and 12b.

The recorder 16 reciprocates between the first powder material container 12a and the second powder material container 12b.

Then, the powder material supplied by raising the feed tables 14a and 14b is transported to the modeling region 11a, and a thin layer 15a of the powder material is formed in the shape of the modeling table 13a. The thickness of the thin layer 15a of the material is determined by the amount of descent of the modeling table 13a.

As powder materials, polyamide, polypropylene, polylactic acid, polyethylene (PE), polyethylene terephthalate (PET), polystyrene (PS), acrylonitrile-butadiene-styrene copolyma (ABS), ethylene-vinyl acetate copolyma (EVA), styrene-acrylonitrile Thermoplastic resins such as copolyma and polycaprolactone can be used.

The modeling container 11 and the first and second powder material containers 12a and 12b are used to prevent deterioration due to oxidation of the powder material and damage to the laser light emitting portion 102 due to the vapor of the material generated by irradiation with the laser light. , Housed in a closed chamber 17.

As shown in FIG. 3, the chamber 17 is provided with an inert gas introduction port 17a and an exhaust port 17b, and is filled with the inert gas during modeling.

(B) Configuration of Heating Means FIG. 3 is a diagram showing a modeling container 11, powder material containers 12a and 12b, and a heating means 11b of the chamber 17.

The powder bed fusion bonding device 10 is provided with heaters (not shown) wound around the modeling container 11 and the powder material storage containers 12a and 12b, respectively.

Further, above the modeling container 11, four infrared heaters 11b arranged so as to surround the four sides of the modeling region 11a are provided.

The amount of heat generated by the infrared heater 11b can be individually set by adjusting the electric power supplied to the infrared heater 11b. By appropriately adjusting the combination of the calorific value of the infrared heater 11b, the surface of the modeling region 11a is kept at a uniform temperature.

At the time of modeling, the infrared heater 11b is used to keep the powder material in the modeling region 11a at a temperature slightly lower than its melting point.

(C) Configuration of Laser Light Ejecting Unit 102 FIG. 2 is a block diagram showing a laser light emitting unit 102 of the powder bed fusion coupling device according to the embodiment.

As shown in FIG. 2, the laser light emitting unit 102 includes a laser light source 23 that emits laser light, an optical scanning element 21, and a focus optical system 21c. These light emitting units 102 are installed outside the chamber 17.

As the laser light source 23, for example, a YAG laser light source that emits a laser beam in a near infrared region having a wavelength of about 1000 nm, a fiber laser light source, or the like can be used.

The wavelength used may be appropriately changed in consideration of the wavelength absorption rate and cost performance of the powder material. For example, a high-power CO ₂ laser light source that emits laser light in the far infrared region having a wavelength of about 10,000 nm is used. May be good.

The optical scanning element 21 includes a galvanometer mirror (X mirror) 21a that scans the laser beam in the X direction by changing the angle with respect to the laser beam and a galvanometer mirror (Y) that scans the laser beam in the Y direction by changing the angle with respect to the laser beam. It is equipped with a mirror) 21b.

The optical scanning element 21 scans the laser beam on the modeling region 11a in the X and Y directions.

Further, the focus optical system 21c has a function of adjusting the focal length of the laser beam. The focus optical system 21c operates so as to match the focal length, which changes according to the scanning position of the laser beam, with the surface of the thin layer 15a of the powder material.

By aligning the optical axis of the optical scanning element 21 (the central axis of the scanning range) with the center of the modeling region 11a, the relationship between the scanning position and the focal length becomes a target around the optical axis, and the focus optical system The control of 21c becomes easy, and irradiation can be performed with high accuracy.

Therefore, it is preferable that the optical axis of the optical scanning element 21 is aligned with the center of the modeling region 11a.

The X mirror 21a, the Y mirror 21b, and the focus optical system 21c of the optical scanning element 21 are operated by the control signal of the XYZ driver 24.

The XYZ driver 24 is controlled by the controller (control device) 25, and ON (lighting) and OFF (turning off) of the laser light source 23 are also controlled by the controller 25. As the controller 25, for example, a computer having a CPU (Central Processing Unit) and a memory in which a control program is stored can be used.

The laser light emitted from the laser light source 23 irradiates the thin layer 15a of the material on the part table 13a of the modeling unit 101 through the paths of the focus optical system 21c, the X mirror 21a, and the Y mirror 21b in order.

The laser beam is operated by the control of the optical scanning element 21 by the controller 25 to selectively irradiate the sintered or molten region.

Further, while the laser beam is being scanned, the lens of the optical system 21c constantly moves to adjust the focal length so that the laser beam focuses on just the surface of the thin layer 15a of the powder material.

The control of the optical scanning element 21 is performed based on the slice data (drawing pattern) of the three-dimensional model to be produced.

(D) Configuration of Infrared Camera 31 and Laser Window 32 The optical scanning element 21 is mounted above the modeling region 11a as shown in FIG. In the present embodiment, the optical scanning element 21 is arranged so that the center of the modeling region 11a and the optical axis of the optical scanning element 21 are aligned with each other from the viewpoint of facilitating the control thereof and ensuring the accuracy.

Further, the infrared camera 31 is arranged adjacent to the optical scanning element 21.

By arranging the infrared camera 31 as close as possible to the center of the modeling region 11a in this way, the distortion of the image when the modeling region 11a is imaged is reduced. As a result, the correspondence between the pixel position of the captured image data and the position of the actual modeling region 11a can be obtained relatively accurately.

During modeling, a part of the powder material heated by the irradiation of laser light or the infrared heater 11b may sublimate and reattach to the inner wall of the chamber 17. Therefore, if optical devices such as the optical scanning element 21 and the infrared camera 31 are directly attached to the chamber 17, these optical devices will break down in a short time.

Therefore, the laser window 32 is arranged between the optical scanning element 21, the infrared camera 31, and the modeling container 11.

The laser window 32 is made of, for example, a disk-shaped crystal substrate made of zinc selenide, and transmits laser light and infrared rays radiated from the surface of the modeling region 11a.

The laser light of the laser light emitting unit 102 is irradiated into the chamber 17 through the laser window 32.

Further, in the present embodiment, in order to prevent the powder material from adhering to the laser window 32, an outlet 32a for blowing an inert gas onto the laser window 32 is provided. The spout 32a is provided around the laser window 32, and the flow of the inert gas ejected from the spout 32a pushes the vapors and fine particles of the powder material back into the chamber 17 to reattach to the laser window 32. Can be prevented.

The optical axis of the optical scanning element 21 is arranged above the modeling container 11 so as to cover the entire area of the modeling region 11a within the scanning range. At this time, in order to facilitate focus control, it is preferable that the center O of the modeling region 11a and the center of the optical axis of the optical scanning element 21 are aligned with each other.

As described above, the laser window 32 is required to secure the scannable range of the optical scanning element 21 even when the optical scanning element 21 is arranged above the center O of the modeling region 11a.

Further, since the ejection port 32a protruding from the periphery of the laser window 32 may limit the irradiation range, it is preferable to arrange the center of the laser window 32 as close to the center of the optical scanning element 21 as possible.

On the other hand, it is also required to set the position of the laser window 32 so that the infrared camera 31 can cover the entire area of the modeling region 11a in the field of view.

In order to satisfy such a condition, it is conceivable to increase the size of the laser window 32 within the range necessary for securing the scanning range of the optical scanning element 21.

However, as the size of the laser window 32 increases, it becomes very expensive, so it is preferable to minimize the size increase.

FIG. 4 is a plan view showing the arrangement of the optical scanning element 21, the infrared camera 31, and the laser window 32.

Therefore, in the present embodiment, as shown in FIG. 4, the position of the center P of the laser window 32 is shifted from the center O of the modeling container 11 toward the infrared camera 31.

That is, the center P of the laser window 32 is not arranged directly under the optical scanning element 21, but is arranged between the infrared camera 31 and the optical scanning element 21.

Further, the center Q of the infrared camera 31 can be arranged on an extension of the line connecting the center O of the optical scanning element 21 and the center P of the laser window 32. Here, the center of the infrared camera 31 means the mechanical center of the infrared camera 31, and the center of the lens may not match this.

FIG. 5 is a diagram showing an arrangement relationship between the modeling container 11, the optical system (optical scanning element) 21, and the infrared camera 31.

As shown in FIG. 5, when the center P of the laser window 32 is arranged between the optical scanning element 21 and the infrared camera 31, for example, in a small powder bed fusion coupling device 10 having a modeling region 11a of about 150 mm × 150 mm, The field of view of the infrared camera 31 can be secured while aligning the scanning range of the optical scanning element 21 with the center of the modeling region 11a.

Therefore, according to the powder bed fusion coupling device 10 of the present embodiment, the surface of the modeling region 11a can be photographed by the infrared camera 31 without removing the laser light emitting unit 102.

In addition, the temperature distribution on the surface of the modeling region 11a during modeling can be detected in real time, and the conditions for the heater 11b can be easily set.

(2) Description of Adjustment Step Using Infrared Camera 31 Next, an adjustment step performed before modeling by the powder bed fusion bonding device 10 will be described with reference to FIG.

FIG. 6 is a flowchart of the adjustment process in the powder bed fusion bonding device 10.

First, as shown in step S11 of FIG. 6, the powder material 15 is set up.

Here, the part table 13a is attached to the modeling container 11 so that it can move up and down along the inner wall of the modeling container 11 shown in FIG. Further, the feed table 14a is also attached to the left and right powder material containers 12a and 12b.

Next, the left and right feed tables 14a are lowered, and the powder material 15 is placed on the feed table 14a.

After that, the recorder 16 is moved a plurality of times to spread the thin layer 15a of the powder material in the modeling region 11a. In addition, the inert gas is introduced from the gas introduction port 17a.

Next, in step S12, the powder material 15 is heated by the heaters around the containers 11, 12a and 12b, and the surface of the thin layer 15a of the powder material in the modeling region 11a is heated by the infrared heater 11b. Here, it may be heated to the same temperature as in the actual molding, for example, the surface of the powder material is set to a temperature about 5 to 15 ° C. lower than the melting point thereof.

Next, in step S13, the surface of the modeling region 11a is imaged by the infrared camera 31. Since the intensity of infrared rays emitted from each part of the modeling region 11a increases or decreases according to the temperature of that part, the brightness value detected by the infrared camera 31 reflects the temperature distribution. The image data from the infrared camera 31 is sent to the control unit 33 and converted into a temperature distribution.

Next, in step S14, under the control of the control unit 33, the combination of the outputs of the infrared heaters 11b arranged around the modeling container 11 is adjusted so that the temperature of the surface of the modeling region 11a becomes uniform.

After that, in step S15, the control unit 33 records the combination of the output values of the infrared heater 11b set in step S15 as adjustment data, and ends the adjustment step.

The output data of the infrared heater 11c recorded in step S15 is used in the subsequent modeling.

In the above example, the case where the infrared camera 31 is used in the adjustment step before the start of modeling has been described, but the present invention is not limited to this, and the infrared heater 11c is used during modeling based on the detection result of the infrared camera 31. The output may be directly controlled by the control unit 33.

10 ... Powder bed fusion coupling device, 11 ... Modeling container, 11a ... Modeling area, 12a, 12b ... Powder material storage container, 13a ... Part table, 13b, 14b ... Support shaft, 14a ... Feed table, 15 ... Powder material, 15a ... Thin layer, 15b ... Solidified layer, 16 ... Recorder, 17 ... Chamber, 17a ... Gas inlet, 17b ... Gas outlet, 21 ... Optical scanning element, 21a ... X mirror, 21b ... Y mirror, 21c ... Focus optics System, 23 ... laser light source, 24 ... XYZ driver, 25 ... controller, 31 ... infrared camera, 32 ... laser window, 32a ... spout, 33 ... control unit, 101 ... modeling unit, 102 ... laser light emitting unit.

Claims (4)

A modeling container that houses a modeled object together with a thin layer of resin powder material,
A plurality of infrared heaters that heat the surface of the modeling container,
A laser light source that generates a laser beam that irradiates a thin layer of the resin powder material,
A chamber for accommodating the modeling container and
A laser window provided on the upper surface of the chamber and
An optical scanning element that irradiates a thin layer of the resin powder material with the laser beam to scan through the laser window.
An infrared camera arranged adjacent to the optical scanning element and capturing the temperature distribution of a thin layer of the resin powder material on the surface of the modeling container through the laser window.
Equipped with a,
The optical axis of the optical scanning element coincides with the center of the modeling container,
A powder bed fusion coupling device characterized in that the center of the laser window is located between the optical scanning element and the infrared camera. The center of the infrared camera, a powder bed fusion bonding apparatus according to claim 1, characterized in that it is arranged on the extension of the center and a line connecting the center of the laser window of the optical scanning element. A control unit that controls the output of the infrared heater based on the temperature distribution of the thin layer of the resin powder material.
The powder bed melt-bonding apparatus according to claim 1 or 2 , wherein the powder bed melt-bonding apparatus is provided. The powder bed melt-bonding apparatus according to any one of claims 1 to 3 , wherein the laser window is provided with an outlet for blowing an inert gas.

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