JPWO2020044522A1 - Powder bed melt coupling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powder bed melt-bonding device capable of suppressing roughening of the surface of a layer of a powder material. SOLUTION: A powder supply unit 11 and 13 for supplying a powder material M, a table 15 provided side by side on the powder supply unit 11 and 13, and a roller having a rotation axis C in a horizontal plane and facing the table 15. By moving the 20 and the roller 20 along the horizontal plane, the powder material M is transported from the powder supply units 11 and 13 onto the table 15, and the moving speed v of the roller can be freely set. And, the roller 20 is rotated in the direction opposite to the rotation direction in which the roller 20 naturally rolls on the powder material M on the table 15, and the rotation speed N of the roller 20 can be freely set. A powder bed fusion coupling device 10 having 40 and 40 is provided. [Selection diagram] Fig. 1

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.

As a technique for creating a prototype or a small-lot, high-mix model, there is a technique for depositing a layer of powder material and then irradiating the layer with a laser beam to solidify it. In this technique, a three-dimensional model can be produced by repeating the accumulation and solidification of layers of powder material.

A roller called a recoater is used to deposit layers of powder material. The recorder is a roller having a function of moving on a table for producing a modeled object to form a layer of powder material and a function of rotating itself to flatten the surface of the layer of powder material.
However, if the moving speed and the rotating speed of the recorder are arbitrary, the surface of the layer of the powder material becomes rough, and as a result, the physical properties of the modeled object such as the tensile elastic modulus and the tensile elongation are deteriorated.

Japanese Unexamined Patent Publication No. 2016-175317

An object of the present invention is to provide a powder bed melt-bonding device capable of suppressing roughening of the surface of a layer of a powder material.

According to one aspect, a powder supply unit for supplying the powder material, a table provided side by side with the powder supply unit, a roller having a rotation axis in the horizontal plane and facing the table, and a roller along the horizontal plane. By moving the roller, the powder material is transported from the powder supply unit onto the table, and a moving drive unit capable of freely setting the moving speed of the roller and the roller on the table. Provided is a powder bed fusion coupling device having a rotation drive unit that rotates the roller in a rotation direction opposite to the rotation direction that naturally rolls on the powder material and can freely set the rotation speed of the roller. NS.

According to one aspect, by making it possible to freely set the moving speed and the rotating speed of the roller, it is possible to obtain the moving speed and the rotating speed suitable for the powder material, and the surface of the layer formed from the powder material can be obtained. It is possible to prevent the material from becoming rough and to prevent the physical properties of the modeled object obtained from the layer from deteriorating.

FIG. 1 (a) is a top view of the powder bed fusion coupling device according to the present embodiment, and FIG. 1 (b) is a cross-sectional view taken along the line I-I of FIG. 1 (a). FIG. 2A is a schematic cross-sectional view of a moving drive unit that moves the rollers, and FIG. 2B is a schematic cross-sectional view of the rotary drive unit that rotates the rollers. It is a schematic cross-sectional view (the 1) for demonstrating the laminated molding method using a powder bed melt-bonding apparatus. It is a schematic cross-sectional view (No. 2) for demonstrating the laminated molding method using a powder bed melt-bonding apparatus. It is a schematic cross-sectional view (No. 3) for demonstrating the laminated molding method using a powder bed melt-bonding apparatus. It is sectional drawing of a roller. It is a schematic cross-sectional view for demonstrating the moving speed and the peripheral speed of a roller. It is a figure which shows the optical photograph of the surface of the layer obtained by various combinations of peripheral speed and moving speed when polyphenylene sulfide is used as a powder material. It is a figure which shows the optical photograph of the surface of the layer obtained by various combinations of peripheral speed and moving speed when polypropylene is used as a powder material. It is a table obtained by investigating the tensile strength of a modeled object when the peripheral speed of the roller is changed while the moving speed of the roller is fixed at 150 mm / sec. It is a table obtained by investigating the tensile elastic modulus of a modeled object when the peripheral speed of the roller is changed while the moving speed of the roller is fixed at 150 mm / sec. It is a table obtained by investigating the tensile elongation rate of a modeled object when the peripheral speed of the roller is changed while the moving speed of the roller is fixed at 150 mm / sec. It is a figure which shows the photograph of the large trace (striped pattern) of the roller 20 seen on the surface of a layer 23.

The present embodiment will be described below with reference to the accompanying drawings.
FIG. 1A is a top view of the powder bed fusion coupling device according to the present embodiment.

As shown in FIG. 1A, the powder bed fusion coupling device 10 has a first powder container 11, a modeling container 12, and a second powder container 13. Each of these containers 11 to 13 is arranged side by side on a metal top plate 14.

Further, the first powder container 11 and the second powder container 13 are examples of the powder supply unit, and accommodate the powder material M for modeling a three-dimensional modeled object. Examples of such powder material M include polypropylene, polyphenylene sulfide, polybutylene terephthalate, nylon 6, nylon 11, nylon 12, and elastomer powder. A filler such as glass beads or carbon fiber may be kneaded with these powders.
Further, a roller 20 called a recorder is arranged on the top plate 14.
FIG. 1 (b) is a cross-sectional view taken along the line I-I of FIG. 1 (a).

As shown in FIG. 1 (b), each of the first powder container 11 and the second powder container 13 has a first feed table 17a and a second feed table 17b that can be raised and lowered along the vertical direction. Is provided.

Further, the roller 20 has a cylindrical shape having a rotation axis C in a horizontal plane, and by reciprocating on the top plate 14, the powder material M in each of the powder containers 11 and 13 is transported into the modeling container 12 to carry the powder. A layer 23 of material M is formed.
On the other hand, the modeling container 12 accommodates the part table 15. The part table 15 is a table that can be raised and lowered in the vertical direction, on which the above-mentioned layer 23 is laminated.

A laser optical system 25 that generates a laser beam 24 is provided above the modeling container 12. The laser optical system 25 controls the movement of the mirror and the lens based on the slice data of the modeled object P to be created, irradiates the uppermost layer 23 with the laser beam 24, and the layer 23 of the portion corresponding to the modeled object P. Is heated to melt.
FIG. 2A is a schematic cross-sectional view of the moving drive unit 30 that moves the roller 20.

The movement drive unit 30 is a mechanism for moving the roller 20 along the horizontal plane, and has a first motor 31 and a pulley 32. A first timing belt 33 is suspended between the first motor 31 and the pulley 32, and a frame 34 is fixed to the first timing belt 33. The frame 34 rotatably supports the roller 20 and moves along the horizontal plane together with the first timing belt 33.
The rotation speed of the first motor 31 can be arbitrarily set. As a result, the moving speed v of the roller 20 along the horizontal plane can be freely set.
FIG. 2B is a schematic cross-sectional view of the rotation drive unit 40 that rotates the roller 20.

The rotation drive unit 40 is a mechanism for rotating the roller 20 in a rotation direction opposite to the rotation direction in which the roller 20 naturally rolls on the powder material M on the part table 15 (see FIG. 1B). In this example, the rotary drive unit 40 has a second motor 41 and pulleys 42, 43. A second timing belt 44 is suspended on each of the roller 20, the second motor 41, and the pulleys 42, 43, and the rotation of the second motor 41 causes the roller 20 to rotate at a rotation speed N. do. The rotation speed N is the rotation speed (rpm) of the roller 20 per unit time.

According to such a mechanism, since the second timing belt 44 is deformed as the roller 20 moves on the horizontal plane at the moving speed v, the roller 20 can be rotated without hindering the movement of the roller 20. ..
Further, in this example, the rotation speed of the second motor 41 can be arbitrarily set, whereby the rotation speed N of the roller 20 can be freely set.
Next, a laminated modeling method using the powder bed fusion bonding device 10 will be described.
3 to 5 are schematic cross-sectional views for explaining a laminated molding method using the powder bed fusion bonding device 10.

When resin powder or the like is used in the laminated molding, the heaters (not shown) of the containers 11 to 13 are operated so that the powder material M does not cool down during the laminated molding, and the containers 11 to 13 are moved. It may be heated to a predetermined temperature.
It is desirable to reduce the oxygen concentration by filling, for example, nitrogen gas so as to prevent the resin powder from being oxidized by heating with a heater or melting with a laser. At that time, it is more preferable to prevent the inflow of oxygen from the gaps in the modeling chamber and the exhaust side by setting the pressure in the modeling chamber to be slightly higher than the atmospheric pressure.

Then, as shown in FIG. 3A, the roller 20 is arranged at the open end of the first powder container 11.

Next, as shown in FIG. 3B, the first feed table 17a is raised, and the part table 15 is lowered by the thickness of one layer 23 (see FIG. 1B), for example, about 80 μm to 120 μm. Let me. Since the thickness of the layer 23 is determined from the viewpoint of whether the modeled object P is required to have high machining accuracy and whether the powder material M is a material that can be easily heated, the amount of descent of the part table 15 is determined accordingly. Is also determined.
Further, the second feed table 17b is lowered to such an extent that the powder material M not used for forming the layer 23 is sufficiently accommodated.

Next, as shown in FIG. 3C, the moving drive unit 30 moves the roller 20 along the horizontal plane. As a result, the powder material M is carried to the modeling container 12 while the roller 20 faces the part table 15, and the layer 23 of the powder material M is formed on the part table 15. At this time, the rotation drive unit 40 rotates the roller 20 in the direction opposite to the direction in which the roller 20 naturally rolls on the powder material M. As a result, a lump of the powder material M is generated in the traveling direction of the roller 20, and the roller 20 moves on the lump, so that the flatness of the surface of the layer 23 is improved.
Next, as shown in FIG. 4A, the remaining powder material M is carried to the second powder container 13 by further moving the roller 20.

After that, as shown in FIG. 4B, the laser beam 24 is scanned on the layer 23 based on the slice data of the modeled object P to be produced, and the layer 23 of the portion to be the modeled object P is melted. The layer 23 of the melted portion is solidified by natural cooling to become a solidified layer 23a.

Subsequently, as shown in FIG. 4C, the second feed table 17b is raised and the part table 15 is lowered by one layer of the layer 23. Similarly, the first feed table 17a is also lowered.

Then, as shown in FIG. 5A, the moving drive unit 30 moves the roller 20 to convey the powder material M to the modeling container 12, and forms a new layer 23 on the solidified layer 23a. In this case as well, as in the step of FIG. 3C, the rotation drive unit 40 rotates the roller 20 in the direction opposite to the roller 20 naturally rolling on the powder material M, so that the surface of the layer 23 is formed. The flatness of the

Next, as shown in FIG. 5B, the laser beam 24 is scanned on the uppermost layer 23 to melt the layer 23 of the portion to be the modeled object P. The layer 23 of the melted portion is solidified by natural cooling to become a solidified layer 23a.
By repeating such a step, a modeled object P formed by laminating a plurality of solidified layers 23a can be produced.

In the present embodiment, an example in which the roller 20 reciprocates on the top plate 14 is shown, but the present embodiment is not limited to this. For example, the roller 20 may move in only one of the two directions reciprocating on the top plate 14.
FIG. 6 is a cross-sectional view of the roller 20.
As shown in FIG. 6, the roller 20 has a cylindrical main body 20a and a coating film 20c formed on the cylindrical surface 20b of the main body 20a.

The material of the main body 20a is not particularly limited, but in this example, stainless steel, which is easy to lathe, is used as the material. Further, the coating film 20c is a nickel film harder than the main body 20a. By using a material harder than the main body 20a as the material of the coating film 20c in this way, it is possible to prevent the roller 20 from being worn and worn by the powder material M.
Next, the moving speed and the peripheral speed of the roller 20 will be described.
FIG. 7 is a schematic cross-sectional view for explaining the moving speed v (mm / sec) and the peripheral speed w (mm / sec) of the roller 20.
The moving speed v (mm / sec) is defined as the speed at which the rotation axis C of the roller 20 moves in the horizontal direction.

On the other hand, the peripheral velocity w (mm / sec) is defined as the absolute value of the velocity of the edge of the roller 20 when viewed from the coordinate system moving with the roller 20. If the diameter of the roller 20 is R and the rotation speed of the roller 20 is N (rpm), the peripheral speed w is w = π × R × N / 60 (mm / sec).

In the powder bed fusion coupling device 10 according to the present embodiment, the moving speed v can be freely set by the moving driving unit 30 as described above. Further, since the rotation speed N can be freely set by the rotation drive unit 40, the peripheral speed w can also be freely set.

At present, the inventor of the present application has set the condition that the peripheral speed w is 0.97 times the moving speed v and the condition that the peripheral speed w is 1.23 times the moving speed v. Is in operation. In order to find a condition preferable to these two conditions, the inventor of the present application investigated the influence of the peripheral speed w and the moving speed v on the layer 23. The results of the survey will be described below.
<About the surface shape of layer 23>
The inventor of the present application investigated how the surface shape of the layer 23 changes depending on the peripheral speed w and the moving speed v. The survey results are shown in FIG.

FIG. 8 is a diagram showing an optical photograph of the surface of the layer 23 obtained by various combinations of peripheral speed w and moving speed v when polyphenylene sulfide is used as the powder material M.

In this survey, polyphenylene sulfide having an average particle size of about 50 μm was used as the powder material M, and the surface of the layer 23 obtained from the powder material M was photographed. The numerical value below each photograph represents the ratio (w / v) of the peripheral speed w and the moving speed v.
As shown in FIG. 8, when compared at the same moving speed v, it was found that the higher the peripheral speed w, the smaller the unevenness on the surface of the layer 23, and a good quality layer 23 can be obtained.

In order to confirm whether such a tendency can be seen in another powder material M, the inventor of the present application used polypropylene having an average particle size of about 50 μm as the powder material M, and conducted the same investigation as above. The survey results are shown in FIG.

FIG. 9 is a diagram showing an optical photograph of the surface of the layer 23 obtained by various combinations of peripheral speed w and moving speed v when polypropylene is used as the powder material M. As in FIG. 8, the numerical value below each photograph represents the ratio (w / v) of the peripheral speed w and the moving speed v.

As shown in FIG. 9, it was clarified that even in polypropylene, when compared at the same moving speed v, the unevenness of the surface of the layer 23 becomes smaller as the peripheral speed w becomes faster.

In the powder bed fusion coupling device 10 according to the present embodiment, each of the moving speed v and the peripheral speed w can be freely set as described above. Therefore, by selecting a combination that reduces the unevenness of the surface of the layer 23 from the plurality of combinations of the moving speed v and the peripheral speed w, the unevenness of the surface of the layer 23 is reduced regardless of the type of the powder material M. be able to.

Further, in both the results of FIGS. 8 and 9, by setting the peripheral speed w to 1.7 times or more the moving speed v, the roughness of the surface of the layer 23 tends to be suppressed. Therefore, from the viewpoint of preventing the surface of the layer 23 from being roughened, it is preferable that the peripheral speed w is 1.7 times or more the moving speed v.

FIG. 13 is a photograph showing a large trace (striped pattern) of the roller 20 seen on the surface of the layer 23.
According to another investigation by the inventor of the present application, if the peripheral speed w is 2.4 times or more the moving speed v, the roller 20 shown in FIG. 13 is not shown in the photographs of FIGS. 8 and 9. It was also revealed that large marks were left on the surface of layer 23.

Therefore, in order to prevent the traces of the rollers 20 from being left on the surface of the layer 23 and to suppress the roughness of the surface of the layer 23, the peripheral speed w is set to 1.7 to 2.4 times the moving speed v. It is preferable to do so.
<Physical characteristics of model P>
The inventor of the present application investigated how the physical properties of the modeled object P change depending on the peripheral speed w and the moving speed v. The survey results are shown in FIGS. 10 to 12.
・ Tensile strength

FIG. 10 is a table obtained by investigating the tensile strength (MPa) of the modeled object P when the peripheral speed w is changed while the moving speed v is fixed at 150 mm / sec. The peripheral speed w is represented by the value of the ratio with the moving speed v. In this survey, samples S1 to S5 were prepared for each peripheral velocity w, and the average value of the tensile strengths of these samples was calculated. These are the same in each investigation of tensile elastic modulus and tensile elongation, which will be described later.
As shown in FIG. 10, it can be seen that there is no significant difference in tensile strength in the range where the peripheral speed w is 0.3 to 3.4 times the moving speed v.
・ Tension elastic modulus

FIG. 11 is a table obtained by investigating the tensile elastic modulus (MPa) of the modeled object P when the peripheral speed w is changed while the moving speed v is fixed at 150 mm / sec. In sample S5, when the ratio of the peripheral speed w and the moving speed v was 3.1, the measured value could not be obtained due to poor contact of the strain gauge.
Regarding the tensile elastic modulus, when the ratio of the peripheral speed w and the moving speed v is 3.1, the average tensile strength has a value of 797 MPa, but when the peripheral speed w is 2.4 times or less of the moving speed v, the tensile modulus A stable value with an elastic modulus of 760 MPa or more has been obtained.

-Tensile elongation rate FIG. 12 is a table obtained by investigating the tensile elongation rate (%) of the modeled object P when the peripheral speed w is changed while the moving speed v is fixed at 150 mm / sec.
When the peripheral speed w is 1.0 times or more the moving speed v, a stable value with a tensile elongation rate of 320% or more is obtained. Further, in the range where the peripheral speed w is 1.7 to 2.4 times the moving speed v, a more stable value with a tensile elongation rate of 440% or more is obtained.

From the results of FIGS. 8 to 13 described above, by setting the peripheral speed w to 1.0 to 2.4 times the moving speed v, the tensile elastic modulus of the modeled object P stably exceeds 760 MPa and the tensile elongation It was clarified that the rate stably exceeded 320% and that the large marks (striped pattern) (striped pattern) of the rollers 20 seen on the surface of the layer 23 did not occur.

Further, by narrowing the peripheral speed w to 1.7 to 2.4 times the moving speed v, the tensile elongation rate exceeds 440% and the surface roughness of the layer 23 can be prevented (FIGS. 8 and 9). It was revealed that favorable results were obtained.

As described above, the inventor of the present application presently powders under two conditions: a condition in which the peripheral speed w is 0.97 times the moving speed v and a condition in which the peripheral speed w is 1.23 times the moving speed v. Although the floor melt coupling device 10 is in operation, according to the above results, a more suitable range (1.7 to 2.4 times) than the latter condition (1.23 times) was found. By operating the powder bed melt coupling device 10 within this range (1.7 times to 2.4 times), it becomes possible to produce a modeled product P having more stable physical property values than the current state.

10 ... powder bed melt coupling device, 11 ... first powder container, 12 ... modeling container, 13 ... second powder container, 14 ... top plate, 15 ... part table, 17a ... first feed table, 17b ... second 2 feed table, 20 ... roller, 20a ... main body, 20b ... cylindrical surface, 20c ... coating, 23 ... layer, 24 ... laser light, 25 ... laser optical system, 30 ... mobile drive unit, 31 ... first motor, 32, 42, 43 ... pulley, 33 ... first timing belt, 34 ... frame, 40 ... rotary drive unit, 41 ... second motor, 44 ... second timing belt.

Claims (6)

The powder supply unit that supplies the powder material and
A table provided side by side in the powder supply unit and
A roller having a rotation axis in a horizontal plane and facing the table,
By moving the roller along a horizontal plane, the powder material is transported from the powder supply unit to the table, and a moving drive unit capable of freely setting the moving speed of the roller.
A rotation drive unit capable of rotating the roller in a rotation direction opposite to the rotation direction in which the roller naturally rolls on the powder material on the table and freely setting the rotation speed of the roller.
Powder bed fusion coupling device with. The powder bed fusion coupling device according to claim 1, wherein the rotation drive unit can set a plurality of different rotation speeds with respect to the same movement speed. The powder bed melt-bonding apparatus according to claim 1 or 2, wherein the peripheral speed of the roller is 1.0 to 2.4 times the moving speed. The powder bed melt-bonding apparatus according to claim 3, wherein the peripheral speed of the roller is 1.7 to 2.4 times the moving speed. The powder bed melt-bonding according to any one of claims 1 to 4, wherein the rotation drive unit has a motor connected to the roller and controls the rotation speed by controlling the rotation speed of the motor. Device. The roller
The main body with a cylindrical surface and
The powder bed melt-bonding apparatus according to any one of claims 1 to 5, which is formed on the cylindrical surface and has a coating film of a material harder than the main body.

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