JP2019130854A - Powder material for powder bed fusion bonded molding and forming method thereof, and powder bed fusion bonded molding - Google Patents

Abstract

To provide a powder material of a powder bed fusion bonded molding and a forming method thereof that suppress static electricity generated in the powder material and prevent defects in production of the molding.SOLUTION: A powder material 1 of a powder bed fusion bonded molding is composed of a resin powder 2 for molding having a first polarity by friction and a charged powder 3 charged in advance to a second polarity opposite to the first polarity.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a powder material of a powder bed fusion bond model, a method for forming the powder material, and a powder bed melt bond model.

  In recent years, there has been an increasing demand for modeling apparatuses for modeling prototype parts for functional tests and parts used in a small variety of products.

  Examples of such a modeling apparatus include an optical modeling apparatus and a powder bed fusion bonding apparatus.

  Among these modeling apparatuses, the powder bed fusion bonding apparatus stores a powder material in a storage container. The powder material is transported from the storage container to the production container by the recoater, and a thin layer of the powder material is formed on the modeling table in the production container. Next, by irradiating a specific region of the thin layer of the powder material with laser light, the powder material is melted and bonded and solidified to form a solidified layer in this region.

  By repeatedly forming such a thin layer of powder material and forming a solidified layer by laser irradiation in the production container, the solidified layer is laminated on the modeling table to produce a three-dimensional modeled object. .

  Further, in the powder bed fusion bonding apparatus, a heater is provided above the storage container and the production container. The thin layer of the powder material is preheated by the heater, and the temperature of the thin layer is raised to a temperature slightly lower than the melting point of the powder material, and then the laser beam is irradiated.

  As a result, the temperature difference between the region receiving the laser beam in the thin layer of the powder material and the surrounding region is reduced, and excessive shrinkage occurs in the solidified layer after the laser beam is irradiated. It is possible to suppress the occurrence of warping.

  Examples of the powder material used in the powder bed fusion bonding apparatus include resin powder, metal powder, ceramic powder, and mixed powders thereof.

JP 2009-13395 A Japanese Patent Laid-Open No. 7-150038

  When a resin powder material is used in the powder bed fusion bonding apparatus, when the powder material is transported from the storage container to the production container via the transport plate, static electricity is generated in the powder material due to friction between the powder materials.

  Since the individual powders of the powder material are very light, the powder material may be scattered in the space in the device above the transport plate due to repulsive force (repulsive force) due to static electricity. The scattered powder material may adhere to various devices and parts in the apparatus such as a recoater and a heater by an attractive force due to static electricity, and form a lump of powder material.

  When the lump of powdered material falls onto a transport plate or production container, the thickness of the thin layer formed on the modeling table becomes thicker than the design, or the surface of the thin layer is uneven, causing accurate solidification. Problems such as obstructing the formation of the layer will result in the production of the shaped object.

  As mentioned above, in the powder material of a powder bed fusion bond modeling thing and its formation method, it aims at controlling the static electricity which occurs in a powder material and preventing the malfunction of preparation of a modeling thing.

  According to one aspect of the disclosed technology, the resin powder for modeling having the charging property of the first polarity by friction and the charged powder charged in advance to the second polarity opposite to the first polarity. A powder material for a powder bed fusion bonded structure is provided.

  According to another aspect of the disclosed technology, a modeling resin powder having a first polarity charging property by friction and a charged powder charged in advance to a second polarity opposite to the first polarity. Provided is a method for forming a powder material of a powder bed fusion bonded article having a step of forming a powder material by stirring.

  According to one aspect of the disclosed technology, charged powder that has been charged in advance to a second polarity opposite to the first polarity is added to the resin powder for modeling having the chargeability of the first polarity by friction. Therefore, the charged powder adheres to the surface of the resin powder, and the static electricity generated in the resin powder due to friction during transportation of the powder material can be counteracted to some extent by the charged powder. As a result, static electricity generated in the powder material can be suppressed.

  For this reason, it is possible to avoid the powder material from being scattered in the space in the powder bed fusion bonding apparatus due to static electricity and adhering to various devices and parts. As a result, it is possible to prevent problems in the production of a shaped article due to the dropping of the lump of powder material.

FIG. 1 is a diagram for explaining the states of the resin powder and the charged powder in the powder material according to the present embodiment. FIG. 2 is a diagram for explaining an example of the configuration of a powder bed fusion bonding apparatus for producing a model using the powder material according to the present embodiment. Fig.3 (a) is a top view which shows structures other than the housing | casing of a powder bed fusion | bonding apparatus, FIG.3 (b) is sectional drawing in the II line | wire of Fig.3 (a). FIG. 4 is a cross-sectional view (part 1) in the middle of the formation of the buffer layer of the powder material. FIG. 5 is a cross-sectional view (part 2) in the middle of the formation of the buffer layer of the powder material. FIG. 6 is a cross-sectional view (No. 3) in the middle of the formation of the buffer layer of the powder material. FIG. 7 is a cross-sectional view (part 4) in the middle of the formation of the buffer layer of the powder material. FIG. 8 is a cross-sectional view (No. 1) in the middle of the fabrication of the shaped object. FIG. 9 is a cross-sectional view (No. 2) in the middle of the fabrication of the shaped object. FIG. 10 is a cross-sectional view (No. 3) in the middle of the fabrication of the shaped object. FIG. 11 is a cross-sectional view (part 4) in the middle of the fabrication of the shaped object. FIG. 12 is a cross-sectional view (part 5) in the middle of the fabrication of the shaped object.

  Prior to the description of the present embodiment, items studied by the inventor will be described.

  In order to suppress static electricity generated in the resin powder material, it is conceivable to form a powder material by adding carbon black powder as an antistatic material to the resin powder. Since carbon black has conductivity, static electricity generated in the resin powder through the carbon black can be removed.

  However, the modeled object produced using this powder material becomes black due to carbon black. For this reason, this powder material may not be able to be used depending on the demand for the modeled object.

  It is also conceivable to form a powder material by adding hydrophilic silica powder, which is also used as a fluidity improver, to the resin powder. Hydrophilic silica adsorbs water in the air and a water film is formed on the surface of the silica. Static electricity generated in the resin powder can be removed through this water film.

  However, even a powder material to which hydrophilic silica powder is added may generate static electricity and the powder material may be scattered in the space in the powder bed fusion bonding apparatus. The reason is considered as follows.

  Depending on the type of resin used for producing the modeled object, the temperature in the apparatus may be 100 ° C. or higher due to the preheating, and water in the air in the apparatus may evaporate. In this case, since a water film is not formed on the surface of hydrophilic silica, it is considered that static electricity generated in the resin powder cannot be removed via the water film.

  Based on such examination, in the present embodiment, static electricity generated in the powder material is suppressed as follows.

(This embodiment)
The powder material of the powder bed fusion bonded model according to the present embodiment will be described together with its forming method.

  First, as a raw material for the powder material, a resin powder of a thermoplastic resin and a charged powder are prepared.

  Among these raw materials, the resin powder is, for example, a spherical polypropylene powder having an average particle diameter of about 50 μm.

  The method for forming the resin powder is not particularly limited. For example, a resin powder formed by a suspension polymerization method can be used as the resin powder. Since the resin powder thus formed has a spherical shape, the fluidity is good.

  It is known that the polypropylene is negatively charged by friction from the charge train.

On the other hand, the charged powder is, for example, silica (SiO ₂ ) powder that has been positively charged in advance by chemically treating the surface with hexamethyldisilazane and aminosilane.

  The kind of the silica powder positively charged in advance is not particularly limited. For example, as such silica powder, fumed silica AEROSIL (registered trademark) RA200H powder manufactured by Nippon Aerosil Co., Ltd. may be used.

  The charged powder has various shapes such as a thread shape and a branch shape by aggregation or fusion of silica particles during formation. For this reason, the size of the charged powder is not particularly limited, but is about 500 nm to 3 μm.

  In addition, the polypropylene used as the resin powder is a hydrophobic material. On the other hand, silica used as a charged powder is a hydrophilic material. However, when the above-described chemical treatment is applied to the surface of the silica, the charged powder has a hydrophobic property. However, the property of the charged powder is not limited to being hydrophobic, and the property may be hydrophilic.

  Then, the resin powder and the charged powder as raw materials for the powder material described above are put into, for example, a double cone type dry powder mixer.

  The double-cone type dry powder mixer has a hollow metal mixing container in which the bottom surfaces of two frustoconical containers are joined directly or sandwiching a cylindrical container, and a rotating mechanism for rotating the mixing container. I have.

  The type of dry powder mixer for forming the powder material is not particularly limited. For example, a dry powder mixer in which the shape of the mixing container is V-shaped or cylindrical can be used. Further, a dry powder mixer that includes a stirrer in a mixing container and rotates the stirrer instead of the mixing container to mix the raw materials may be used.

  The raw material of the powder material described above is put into a mixing container of such a dry powder mixer. At that time, the proportion of the charged powder in the powder material is set to 0.1 wt% to 0.3 wt%.

  Then, by rotating the mixing container for about 20 minutes at a rotation speed of about 10 times / minute, the resin powder and the charged powder are stirred and mixed in the mixing container.

  In this way, a powder material is formed. The state of the resin powder and the charged powder in the powder material is schematically shown in FIG.

  When the powder material is formed, the resin powders rub against each other, and the polypropylene resin powder is negatively charged.

  As described above, since polypropylene is a hydrophobic material, it is difficult to form a water film on the surface of the resin powder, and static electricity is likely to be generated in the resin powder.

  Furthermore, the average particle diameter of the resin powder may vary depending on the situation when the resin powder is formed. In general, as the particle size of the resin powder decreases, the specific surface area of the resin powder increases. For this reason, when the resin powder is formed smaller than a specified value (for example, 50 μm), the entire resin powder has a large contact area between the resin powders, and static electricity is easily generated in the resin powder.

  As shown in FIG. 1, in the powder material 1 according to the present embodiment, the charged powder 3 that has been positively charged in advance is added to the resin powder 2 that is negatively charged by friction. The charged powder 3 adheres and the static electricity generated in the resin powder 2 due to friction during the formation of the powder material 1 can be counteracted to some extent by the charged powder 3. As a result, static electricity generated in the powder material 1 can be suppressed.

  For this reason, when the powder material 1 is transferred from the mixing container of the dry powder mixer to another container (for example, a storage container of a powder bed melting and bonding apparatus described later), the powder material 1 is brought into the manufacturing chamber of the powder material 1 by static electricity. 1 can be prevented from scattering. Furthermore, it can also suppress that the powder material 1 adheres to the inner surface and outlet of a mixing container by static electricity. Moreover, these effects are exhibited even when the humidity in the manufacturing chamber is low.

  Moreover, in the powder material 1, since the size of the charged powder 3 is smaller than that of the resin powder 2, the friction between the resin powders 2 is reduced when the charged powder 3 is interposed between the resin powders 2. As a result, the fluidity of the powder material 1 can be improved. That is, the charged powder 3 not only functions as a static electricity suppressing material but also functions as a fluidity improving material.

  For this reason, the powder material 1 can be smoothly transferred from the mixing container to another container. Furthermore, it is possible to further suppress the powder material 1 from adhering to the inner surface or the outlet of the mixing container.

  In this embodiment, such a powder material 1 is used to produce a modeled object.

  Before explaining the method for producing the modeled object, the configuration of the powder bed fusion bonding apparatus for producing the modeled object will be described.

  FIG. 2 is a diagram for explaining an example of the configuration of the powder bed fusion bonding apparatus. Moreover, Fig.3 (a) is a top view which shows structures other than the housing | casing of a powder bed fusion | bonding apparatus, FIG.3 (b) is sectional drawing in the II line | wire of Fig.3 (a).

  As shown in FIG. 2, the powder bed fusion bonding apparatus 4 uses two storage containers 6 and 7 for storing the powder material 1 and the powder material 1 of the storage containers 6 and 7 in the housing 5. A production container 8 in which a model is produced is accommodated.

  As shown in FIG. 3, among these containers 6 to 7, the storage containers 6 and 7 are formed by bending a steel plate and processing such as welding, and are cylinders that open in a rectangular shape when viewed from above. Shaped container.

  In the storage containers 6 and 7, supply tables 9 and 10 are arranged, respectively. The powder material 1 is supplied onto the supply tables 9 and 10. Support rods 11 and 12 connected to a driver (not shown) are attached to the lower surfaces of the supply tables 9 and 10. By driving the driver, the supply tables 9 and 10 are moved up and down in the storage containers 6 and 7 through the support bars 11 and 12.

  On the other hand, the production container 8 is a cylindrical container that is formed by performing processing such as bending and welding on a steel plate and is opened in a square shape when viewed from above.

  A modeling table 13 is arranged in the production container 8. The powder material 1 is supplied onto the modeling table 13. A support bar 14 connected to a driver (not shown) is attached to the lower surface of the modeling table 13. By driving this driver, the modeling table 13 moves up and down in the production container 8 via the support bar 14.

  On the storage containers 6, 7 and the production container 8, a transport plate 15 is installed. A recoater 16 is provided on the transport plate 15.

  The transport plate 15 is a steel plate having a flat upper surface 15a and a lower surface 15b, and is provided with three through holes 15c to 15e.

  Among these through holes 15c to 15e, in FIG. 3, the left through hole 15c and the right through hole 15e have the same shape and size as the upper openings of the storage containers 6 and 7. Further, the central through hole 15 d has the same shape and size as the upper opening of the production container 8.

  And the storage container 6 is arrange | positioned under the through-hole 15c, the preparation container 8 is arrange | positioned under the through-hole 15d, the storage container 7 is arrange | positioned under the through-hole 15e, the through-hole 15c, the through-hole 15d, And the through hole 15 e communicate with the upper opening of the storage container 6, the upper opening of the production container 8, and the upper opening of the storage container 7, respectively.

  Further, the recoater 16 is an elongated metal plate standing in a direction perpendicular to the upper surface 15a of the transport plate 15, and is connected to a driver (not shown). By driving this driver, the recoater 16 moves leftward or rightward on the upper surface 15a of the transport plate 15.

  By moving up and down the supply tables 9 and 10 and the modeling table 13 and moving the recoater 16 to the left and right, the powder material 1 of the storage container 6 or the storage container 7 can be obtained from the upper surface 15a of the transport plate 15 and the through holes 15c to 15e. To the production container 8.

  Upper heating units 17 to 19 and reflection plates 20 and 21 are provided in the space in the housing 5 above the transport plate 15.

  Of the upper heating units 17 to 19, the upper heating unit 17 is disposed above the storage container 6 and includes two rod-shaped heaters 22 and 23. Furthermore, the upper heating unit 18 is disposed above the storage container 7 and includes two rod-shaped heaters 24 and 25.

  These heaters 22 to 25 are infrared heaters or resistance heaters, and are arranged in parallel with each of these side portions inside the longitudinal side portions of the storage containers 6 and 7 when viewed from above. Yes. Thereby, the powder material 1 of the storage containers 6 and 7 is heated from above.

  On the other hand, the upper heating unit 19 is disposed above the production container 8 and includes four rod-shaped heaters 26 to 29.

  These heaters 26 to 29 are infrared heaters or resistance heaters, and are installed in parallel to each of these side portions inside all the side portions of the production container 8 when viewed from above. Thereby, the powder material 1 of the production container 8 is heated from above.

  The reflection plates 20 and 21 are metal plates that are attached to a support column in the housing 5 (not shown) and are set up in a direction perpendicular to the upper surface 15 a of the transport plate 15. And between the production container 8 and the storage container 7.

  In FIG. 3, the left reflector 20 has a mirror-finished surface on the production container 8 side, and the right reflector 21 has a mirror-finished surface on the production container 8 side.

  Thereby, the reflecting plates 20 and 21 can heat the powder material 1 of the production container 8 by reflecting the heat (infrared rays) of the heaters 26 to 29. For this reason, the upper heating part 19 can raise the temperature of the powder material 1 of the production container 8 to a predetermined temperature with low power consumption, and can maintain the temperature.

  The reflecting plates 20 and 21 are connected to the upper portions 20a and 21a via the upper portions 20a and 21a fixed to the support column in the housing 5 and the hinges 20b and 21b, and can swing left and right. It consists of lower parts 20c and 21c. Thereby, the recoater 16 can pass through the reflecting plates 20 and 21 via the lower portions 20c and 21c.

  In addition, although not shown in figure, the powder bed fusion | bonding apparatus 4 is provided with the heating part different from the upper heating parts 17-19.

  For example, a side heating unit that heats the powder material 1 of the manufacturing container 8 from the side is provided on the side of the manufacturing container 8. Further, a lower heating unit for heating the powder material 1 of the production container 8 from below is provided between the modeling table 13 and the support bar 14. Further, the lower surface 15 b of the transport plate 15 is provided with a transport plate heating unit that heats the powder material 1 in contact with the transport plate 15. Each of these heating units includes a plate-like resistance heating type heater.

  The storage containers 6 and 7, the production container 8, the transport plate 15, the recoater 16, the upper heating units 17 to 19, the reflection plates 20 and 21, and the like are disposed in the housing 5.

  On the other hand, two glass windows 5a and 5b are fitted into the upper portion of the housing 5. Among these windows 5a and 5b, a temperature detector 30 is provided above one window 5a.

  The temperature detection unit 30 is a device that detects the temperature by infrared rays, and is disposed inside the side portion of the production container 8 when viewed from above. Thereby, the temperature detection unit 30 can detect the surface temperature of the powder material 1 in the through hole 15 d of the transport plate 15 communicating with the opening of the production container 8.

  Further, a laser beam emitting portion 31 is provided above the other window 5b.

  Although not shown, the laser beam emitting unit 31 is adjusted to the surface of the powder material 1 by changing the laser beam light source, the mirror that scans the laser beam by changing the laser beam emission angle, and the focal length of the laser beam. A lens, a mirror, a driver for driving the lens, and the like are provided. The laser beam emitting portion 31 is disposed inside the side portion of the production container 8 when viewed from above.

  Thereby, the laser beam emitting part 31 can emit and scan the laser beam on the surface of the powder material 1 in the through hole 15d of the transport plate 15.

  The powder bed fusion bonding apparatus 4 is configured as described above. A method for producing a shaped article performed in the powder bed fusion bonding apparatus 4 will be described.

  In the powder bed fusion bonding apparatus 4, in order to prevent the shaped object produced in the production container 8 from being fixed to the upper surface of the shaping table 13, before the production of the shaped object is started, on the shaping table 13. A buffer layer of powder material is formed.

  First, a method for forming the buffer layer will be described. 4 to 7 are cross-sectional views during the formation of the buffer layer.

  For example, the powder bed fusion bonding apparatus 4 before starting the formation of the buffer layer is in the state shown in FIG.

  That is, after the powder material 1 is supplied to each of the storage containers 6 and 7 from the dry powder mixer, the upper surfaces of the powder material 1 of the storage containers 6 and 7 are raised by raising the supply tables 9 and 10. Is the same height as the upper surface 15 a of the transport plate 15.

  Further, by raising the modeling table 13 of the production container 8, the upper surface of the modeling table 13 is flush with the upper surface 15 a of the transport plate 15. Furthermore, the recoater 16 is disposed on the left side of the storage container 6 in the upper surface 15 a of the transport plate 15.

  When the powder bed fusion bonding apparatus 4 is in such a state, first, as shown in FIG. 4 (a), the supply table 9 of the left storage container 6 is raised so that the storage container 6 The powder material 1 is protruded above the upper surface 15a of the transport plate 15 through the through hole 15c.

  Further, the modeling table 13 of the production container 8 is lowered by a thickness of a thin layer of the powder material 1, for example, 0.1 mm, and the supply table 10 of the right storage container 7 is lowered.

  Subsequently, as shown in FIG. 4B, the recoater 16 scrapes the powder material 1 in the storage container 6 protruding from the upper surface 15a by moving the recoater 16 rightward on the upper surface 15a of the transport plate 15. Then, it is transported to the production container 8 through the upper surface 15a and the through hole 15d.

  In this way, the powder material 1 of the storage container 6 is supplied to the production container 8, and the thin layer 32 of the first layer of the powder material 1 is formed on the modeling table 13.

  Further, as shown in FIG. 5A, by moving the recoater 16 in the right direction, the recoater 16 removes the powder material 1 remaining without being used for forming the thin layer 32 through the upper surface 15a and the through holes 15e. To the storage container 7.

  In this way, the remaining powder material 1 is stored in the storage container 7.

  Then, the recoater 16 is stopped at the right position of the storage container 7.

  Next, as shown in FIG. 5B, by raising the supply table 10 of the storage container 7, the powder material 1 of the storage container 7 is placed above the upper surface 15a of the transport plate 15 through the through hole 15e. To protrude.

  Furthermore, the modeling table 13 of the production container 8 is lowered by the thickness of one thin layer of the powder material 1 and the supply table 9 of the storage container 6 is lowered.

  Subsequently, as shown in FIG. 6A, the recoater 16 is moved leftward on the upper surface 15a of the transport plate 15, so that the recoater 16 scrapes off the powder material 1 in the storage container 7 protruding from the upper surface 15a. Then, it is transported to the production container 8 through the upper surface 15a and the through hole 15d.

  In this way, the powder material 1 of the storage container 7 is supplied to the production container 8, and the thin layer 33 of the second layer of the powder material 1 is formed on the modeling table 13.

  Furthermore, as shown in FIG. 6B, the recoater 16 moves the recoater 16 leftward so that the powder material 1 remaining without being used to form the thin layer 33 is removed from the upper surface 15a and the through-hole 15c. To the storage container 6.

  In this way, the remaining powder material 1 is stored in the storage container 6.

  Then, the recoater 16 is stopped on the left side of the storage container 6.

  Thereafter, in the production container 8, the thin layer 34 of the third layer of the powder material 1 is formed on the second thin layer 33 in the same manner as the formation of the first thin layer 32. Further, in the same manner as the formation of the second thin layer 33, the fourth thin layer 35 of the powder material 1 is formed on the third thin layer 34.

  By repeating the formation of such a thin layer of the powder material 1, a plurality of thin layers of the powder material 1 are stacked on the modeling table 13 of the production container 8 as shown in FIG. A buffer layer 36 (for example, 10 mm thick) is formed.

  In FIG. 7, for convenience, four thin layers 32 to 35 of the powder material 1 are shown as the buffer layer 36, but the actual number of thin layers of the powder material 1 depends on the thickness of the buffer layer 36. Number of layers.

  Further, in the powder bed fusion bonding apparatus 4, all the heaters including the heaters 22 to 29 of the upper heating units 17 to 19 are turned on simultaneously with the start of the formation of the buffer layer 36.

  And about the upper heating parts 17-19, based on the data of the surface temperature of the powder material 1 in the through-hole 15d of the conveyance board 15 detected by the temperature detection part 30, the emitted-heat amount of the heaters 22-29 is adjusted. The amount of heat generated is also adjusted for the heaters of the heating units other than the upper heating units 17 to 19.

  As a result, the surface temperature of the powder material 1 in the through-hole 15d of the transport plate 15 is 10 ° C. to 15 ° C. higher than the melting point of the powder material 1, for example, a temperature suitable for starting production of a shaped object in the production container 8. The temperature is raised to about 0 ° C., and this optimum temperature is maintained.

  For example, when polypropylene powder is used as the resin powder 2 of the powder material 1, since the melting point of polypropylene is about 130 ° C., the above-mentioned appropriate temperature is raised to about 115 ° C. to 120 ° C., and this temperature is maintained. The

  In this way, the buffer layer 36 is preheated.

  In this embodiment, in order to perform preheating, all the heaters of the powder bed melting and bonding apparatus 4 are turned on simultaneously with the start of the formation of the buffer layer 36, but the powder bed is melted before the start of the formation of the buffer layer 36. All the heaters of the coupling device 4 may be turned on. For example, when the storage containers 6 and 7 storing the powder material 1 and the production container 8 are stored in the casing 5 of the powder bed fusion bonding apparatus 4, all the heaters of the powder bed fusion bonding apparatus 4 are turned on. It may be.

  After the formation of the buffer layer 36 and the preheating of the buffer layer 36, the fabrication of the shaped object is started.

  A method for producing the shaped object will be described. 8-12 is sectional drawing in the middle of preparation of a molded article.

  In the powder bed fusion bonding apparatus 4, the above-described preheating is performed not only during the formation of the buffer layer 36, but also during the formation of a shaped article on the buffer layer 36. Thereby, the surface temperature of the powder material 1 of the production container 8 is maintained at an appropriate temperature.

  When the powder bed fusion bonding apparatus 4 is in such a state, first, as shown in FIG. 8A, the supply table 9 of the storage container 6 on the left side is raised, so that the storage container 6 The powder material 1 is protruded above the upper surface 15a of the transport plate 15 through the through hole 15c.

  Further, the modeling table 13 of the production container 8 is lowered by the thickness of one thin layer of the powder material 1, and the supply table 10 of the right storage container 7 is lowered.

  Subsequently, as shown in FIG. 8B, the recoater 16 scrapes the powder material 1 in the storage container 6 protruding from the upper surface 15a by moving the recoater 16 rightward on the upper surface 15a of the transport plate 15. Then, it is transported to the production container 8 through the upper surface 15a and the through hole 15d.

  In this way, the powder material 1 of the storage container 6 is supplied to the preparation container 8, and the thin layer 37 of the first powder material 1 is formed on the buffer layer 36 for forming a model.

  Further, as shown in FIG. 9A, by moving the recoater 16 to the right, the recoater 16 removes the powder material 1 remaining without being used for forming the thin layer 37 through the upper surface 15a and the through holes 15e. To the storage container 7.

  In this way, the remaining powder material 1 is stored in the storage container 7.

  Then, the recoater 16 is stopped on the right side of the storage container 7.

  Next, as shown in FIG. 9B, based on the slice data (drawing pattern) of the three-dimensional structure to be manufactured, the movement of the mirror and lens of the laser light emitting unit 31 is controlled, and the output of the light source is changed. By controlling and emitting laser light to the thin layer 37 of the powder material 1 of the first layer and scanning it, the powder material 1 in a specific region in the thin layer 37 of the first layer is melted. Combine and solidify.

  In this way, the first solidified layer 37 a is formed in a specific region of the first thin layer 37.

  Then, emission and scanning of the laser beam are stopped.

  Next, as shown in FIG. 10A, by raising the supply table 10 of the storage container 7, the powder material 1 of the storage container 7 is placed above the upper surface 15a of the transport plate 15 through the through hole 15e. To protrude.

  Furthermore, the modeling table 13 of the production container 8 is lowered by the thickness of one thin layer of the powder material 1 and the supply table 9 of the storage container 6 is lowered.

  Subsequently, as shown in FIG. 10 (b), the recoater 16 scrapes the powder material 1 of the storage container 7 protruding from the upper surface 15a by moving the recoater 16 leftward on the upper surface 15a of the transport plate 15. Then, it is transported to the production container 8 through the upper surface 15a and the through hole 15d.

  In this way, the powder material 1 of the storage container 7 is supplied to the production container 8, and the second layer powder is formed on the thin layer 37 of the powder material 1 on which the first solidified layer 37 a is formed. A thin layer 38 of material 1 is formed.

  Further, as shown in FIG. 11A, the recoater 16 moves the recoater 16 leftward so that the powder material 1 remaining without being used for forming the thin layer 38 is removed from the upper surface 15a and the through holes 15c. To the storage container 6.

  In this way, the remaining powder material 1 is stored in the storage container 6.

  Then, the recoater 16 is stopped on the left side of the storage container 6.

  Next, as shown in FIG. 11B, the laser light emitting unit 31 is controlled to emit laser light to the thin layer 38 of the second layer of powder material 1 and scan the second layer. The powder material 1 in a specific region of the thin layer 38 of the eye is melted, bonded and solidified.

  In this way, the second solidified layer 38 a is formed in a specific region of the second thin layer 38.

  Then, emission and scanning of the laser beam are stopped.

  Thereafter, in the production container 8, in the same manner as the formation of the first thin layer 37 and the solidified layer 37a, the third powder material 1 is formed on the second thin layer 38 and the solidified layer 38a. In the same manner as the formation of the second thin layer 38 and the solidified layer 38a, the fourth thin layer 39 and the solidified layer 39a are formed on the third thin layer 39 and the solidified layer 39a. The thin layer 40 and the solidified layer 40a of the powder material 1 of the layer are formed.

  By repeating the formation of such a thin layer of the powder material 1 for forming a molded article and the formation of a solidified layer with this thin layer, as shown in FIG. A plurality of solidified layers 37a to 40a are stacked to produce a three-dimensional structure 41.

  When the production of the molded article 41 is completed, all the heaters of the powder bed fusion bonding apparatus 4 are turned off.

  Thereafter, the storage containers 6 and 7 and the production container 8 are taken out from the housing 5. And the modeling object 41 buried in the powder material 1 is taken out by raising the modeling table 13 of the production container 8 by a lift (not shown).

  In this way, the shaped article 41 is produced using the powder material 1 in the powder bed fusion bonding apparatus 4.

  In the powder material 1, the powder material 1 is transported from the storage container 6, 7 to the preparation container 8 when the buffer layer 36 is formed and when the molded article 41 is manufactured, and from the one storage container 6, 7 to the other The resin powders 2 are rubbed with each other by the conveyance of the powder material 1 to the storage containers 7 and 6, and the polypropylene resin powder 2 is negatively charged.

  As described above, in the powder material 1 according to the present embodiment, since the charged powder 3 that is positively charged in advance is added to the resin powder 2 that is negatively charged by friction, the buffer layer 36 is formed and formed. Static electricity generated in the resin powder 2 due to friction during the production of the object 41 can be canceled to some extent by the charged powder 3. As a result, static electricity generated in the powder material 1 can be suppressed.

  Therefore, when the powder material 1 is transported, the powder material 1 is scattered by the static electricity in the housing 5 of the powder bed fusion bonding device 4, and the recoater 16, the reflection plates 20 and 21, the heaters 22 to 29, etc. It is possible to avoid the powder material 1 from adhering to the devices and parts in the housing 5. As a result, it is possible to avoid a problem in producing the shaped object 41 due to the drop of the lump of the powder material 1.

  Furthermore, after taking out the model 41 from the powder material 1 of the production container 8, the remaining powder material 1 of the production container 8 and the powder material 1 of the storage containers 6 and 7 are transferred to another container. Also in that case, it is possible to suppress the powder material 1 from scattering into the room due to static electricity. Furthermore, it is possible to suppress the powder material 1 from adhering to the inner surfaces of the storage containers 6 and 7 and the production container 8 due to static electricity. Moreover, these effects are exhibited even when the humidity in the room is low.

  Moreover, in the powder material 1, since the size of the charged powder 3 is smaller than that of the resin powder 2, the friction between the resin powders 2 is reduced when the charged powder 3 is interposed between the resin powders 2. As a result, the fluidity of the powder material 1 can be improved.

  Therefore, the powder material 1 can be smoothly transported from the storage containers 6 and 7 to the production container 8 and can be smoothly transported from the one storage container 6 and 7 to the other storage container 7 and 6. Furthermore, the thin layers 32 to 35 and 37 to 40 of the powder material 1 can be formed on the modeling table 13 of the production container 8 with an equal thickness. As a result, the shaped article 41 can be produced with good quality.

  Furthermore, in the powder material 1, since the charged powder 3 also functions as a fluidity improving material, it is not necessary to add an extra additive to the resin powder 2.

  In other words, for example, after adding silica powder as a fluidity improver to the resin powder 2, a dye-based or metal salt-based charge control agent for controlling the triboelectric charge amount of the resin powder 2 is added. There is no need to add. For this reason, the coloring of the molded article 41 and the change of the physical property of the molded article 41 which are not intended can be avoided.

  The melting point of silica is about 1600 ° C. to 1700 ° C., which is higher than that of polypropylene. For this reason, when each of the thin layers 37 to 40 of the powder material 1 is irradiated with laser light, even if the resin powder 2 of the powder material 1 is melted, the charged powder 3 is not melted. As a result, the charged powder 3 is taken into each of the solidified layers 37a to 40a while maintaining a positively charged state.

  However, even if the charged powder 3 is taken in, the physical property of the molded article 41 does not change. In addition, the charged powder 3 can suppress the charging of the shaped article 41 containing the resin powder 2 as a main component.

  In the above-described embodiment, the case where, among the raw materials of the powder material 1, the polypropylene powder that is negatively charged by friction as the resin powder 2 and the silica powder that is positively charged in advance as the charged powder 3 has been described. However, the combination of the resin powder 2 and the charged powder 3 is not limited to this.

  For example, thermoplastic resins that are negatively charged by friction include polystyrene, polyester, acrylic, polyethylene, and polyvinyl chloride in addition to polypropylene. As the resin powder 2, resin powders of these thermoplastic resins can be used. When such a resin powder 2 is used, a positively charged silica powder is used as the charged powder 3.

  On the other hand, examples of the thermoplastic resin that is positively charged by friction include polyamides such as nylon 6, nylon 11, and nylon 12 (nylon is a registered trademark). As the resin powder 2, resin powders of these thermoplastic resins can be used. When such a resin powder 2 is used, a negatively charged silica powder is used as the charged powder 3 in advance.

Further, as the charged powder 3, in addition to the silica powder described above, a metal such as alumina (Al ₂ O ₃ ) and titania (TiO ₂ ) that has been positively or negatively charged in advance by subjecting the surface to chemical treatment. Oxide powders can be used. Such a charged powder 3 not only functions as a static electricity suppressing material but also functions as a fluidity improving material.

  The raw material of the powder material 1 is not limited to the resin powder 2 and the charged powder 3 alone. For example, depending on the specifications of the molded article 41 to be produced, additives and additions such as carbon fibers and glass beads for improving mechanical strength, pigments and dyes for coloring, etc. are added to the resin powder 2 and the charged powder 3 An agent may be added.

  DESCRIPTION OF SYMBOLS 1 ... Powder material, 2 ... Resin powder, 2a ... Surface of resin powder, 3 ... Charged powder, 4 ... Powder bed fusion bonding apparatus, 5 ... Housing, 6, 7 ... Storage container, 8 ... Preparation container, 9, 10 DESCRIPTION OF SYMBOLS ... Supply table, 13 ... Modeling table, 15 ... Transport plate, 15a ... Upper surface of transport plate, 15c-15e ... Through hole in transport plate, 16 ... Recoater, 17-19 ... Upper heating unit, 20, 21 ... Reflection Plates 22 to 29 ... heaters 30 ... temperature detectors 31 ... laser light emitting parts 32 to 35, 37 to 40 ... powder material thin layers 36 ... powder material buffer layers 37a to 40a ... solidified layers, 41 ... Modeled object.

Claims (5)

A resin powder for modeling having a charge property of the first polarity by friction;
A powder material of a powder bed melt-bonded shaped product, comprising: a charged powder charged in advance with a second polarity opposite to the first polarity.   The powder bed fusion bonded model according to claim 1, wherein the resin powder is a polypropylene powder that is negatively charged by friction, and the charged powder is a positively charged silica powder. Powder material.   The powder material of the powder bed fusion bonded model according to claim 1 or 2, wherein the charged powder is smaller than the size of the resin powder. The step of forming a powder material by stirring the resin powder for modeling having the charging property of the first polarity by friction and the charged powder charged in advance to the second polarity opposite to the first polarity. A method for forming a powder material of a powder bed fusion bonded shaped product, comprising:   It was formed using a powder material having a resin powder for modeling having the charging property of the first polarity by friction and a charged powder charged in advance to the second polarity opposite to the first polarity. A powder bed fusion bonded shaped product characterized by

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