Plasticizing device, three-dimensional shaping device, and injection molding device

Abstract

To stably plasticize a material.SOLUTION: A plasticization device comprises: a flat screw 40 having a groove formation face 48 and having a length in a rotating shaft direction shorter than a length in a direction perpendicular to the rotating shaft direction; a barrel 50 having an opposing face 52 facing the groove formation face 48 and formed with a communication hole 56 communicating with the opposing face 52; and a heating part 58 heating a material fed into a groove 42, and in a region where the groove formation face 48 and the opposing face 52 face each other, a region where the surface free energy of the groove formation face 48 is lower than the surface free energy of the opposing face 52 is provided.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a plasticizing device, a three-dimensional shaping device, and an injection molding device.

Background Art

[0002] Conventionally, various plasticizing devices for plasticizing materials have been used. For example, Patent Document 1 discloses a plasticizing and feeding device including a rotor having a groove-forming surface with a groove formed at one end in the rotational axis direction, and a barrel having a communication hole formed in a facing surface facing the groove-forming surface.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a plasticizing device including a rotor having a groove-forming surface with a groove formed at one end in the rotational axis direction, such as the plasticizing and feeding device of Patent Document 1, and a barrel having a communication hole formed in a facing surface facing the groove-forming surface, there are cases where the material cannot be stably plasticized. This is due to the fact that the material being plasticized and the plasticized material in the region where the groove-forming surface and the facing surface face each other stick to the rotor side, making it difficult to be supplied to the communication hole on the barrel side.

Means for Solving the Problems

[0005] The plasticizing device of the present invention for solving the above problems is rotatable about a rotation axis, has a groove-forming surface on which grooves are formed, and a flat screw whose length in the direction along the rotation axis is shorter than the length in the direction perpendicular to the direction along the rotation axis, a barrel having an opposing surface facing the groove-forming surface and having communication holes formed in the opposing surface, and a heating unit for heating the material supplied into the grooves, wherein the groove-forming surface includes a region having a surface free energy lower than the surface free energy of the opposing surface.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0007] First, the present invention will be schematically described. The plasticizing device according to the first aspect of the present invention for solving the above problems is rotatable about a rotation axis, has a groove-forming surface on which grooves are formed, and a flat screw whose length in the direction along the rotation axis is shorter than the length in the direction perpendicular to the direction along the rotation axis, a barrel having an opposing surface facing the groove-forming surface and having communication holes formed in the opposing surface, and a heating unit for heating the material supplied into the grooves, wherein the groove-forming surface includes a region having a surface free energy lower than the surface free energy of the opposing surface.

[0008] According to this aspect, in a region where the groove formation surface and the opposing surface face each other, there is a region where the surface free energy of the groove formation surface is lower than the surface free energy of the opposing surface. By adopting such a configuration, the material being plasticized and the plasticized material in this region are less likely to stick to the flat screw compared to the barrel, and the material is more likely to head towards the communication holes. Therefore, it is possible to suppress the material from being less likely to be supplied to the communication holes on the barrel side, and the material can be stably plasticized.

[0009] The plasticizing device according to the second aspect of the present invention, in the first aspect, the groove formation surface has a first formation surface and a second formation surface located closer to the center than the first formation surface, and the opposing surface has a first opposing surface facing the first formation surface and a second opposing surface facing the second formation surface and located closer to the center than the first opposing surface, and the surface free energy of the first formation surface is lower than the surface free energy of the first opposing surface, and the surface free energy of the second formation surface is lower than the surface free energy of the second opposing surface.

[0010] According to this aspect, the surface free energy of the first formation surface is lower than the surface free energy of the first opposing surface, and the surface free energy of the second formation surface is lower than the surface free energy of the second opposing surface. By adopting such a configuration, in the entire region where the groove formation surface and the opposing surface face each other, that is, in both the outer region where the first formation surface and the first opposing surface face each other and the central region where the second formation surface and the second opposing surface face each other, the material is less likely to stick to the flat screw compared to the barrel. Therefore, the conveying force of the material towards the communication holes can be improved in the entire region where the groove formation surface and the opposing surface face each other. For this reason, for example, it is possible to inject the plasticized material from a nozzle with a small diameter at a high pressure.

[0011] The plasticizing device according to the third aspect of the present invention is, in the first aspect, wherein the groove forming surface has a first forming surface and a second forming surface located closer to the center than the first forming surface, and the opposing surface has a first opposing surface opposing the first forming surface and a second opposing surface opposing the second forming surface and located closer to the center than the first opposing surface, and the surface free energy of the first forming surface is lower than the surface free energy of the first opposing surface, and the surface free energy of the second forming surface is higher than the surface free energy of the second opposing surface.

[0012] According to this aspect, the surface free energy of the first forming surface is lower than the surface free energy of the first opposing surface, and the surface free energy of the second forming surface is higher than the surface free energy of the second opposing surface. With such a configuration, in the outer region where the first forming surface and the first opposing surface face each other, it becomes more difficult for the material to adhere to the flat screw compared to the barrel. Therefore, in the outer region where the first forming surface and the first opposing surface face each other, the conveying force of the material toward the communication hole can be improved, and in the central region where the second forming surface and the second opposing surface face each other, the material can be plastified thoroughly. For this reason, for example, it is possible to inject a material plastified with a large injection amount using a large-diameter nozzle.

[0013] The plasticizing device according to the fourth aspect of the present invention is, in the first aspect, wherein the groove forming surface has a first forming surface and a second forming surface located closer to the center than the first forming surface, and the opposing surface has a first opposing surface opposing the first forming surface and a second opposing surface opposing the second forming surface and located closer to the center than the first opposing surface, and the surface free energy of the first forming surface is higher than the surface free energy of the first opposing surface, and the surface free energy of the second forming surface is lower than the surface free energy of the second opposing surface.

[0014] According to this aspect, the surface free energy of the first forming surface is higher than that of the first opposing surface, and the surface free energy of the second forming surface is lower than that of the second opposing surface. With such a configuration, in the region on the central side where the second forming surface and the second opposing surface face each other, it becomes more difficult for the material to adhere to the flat screw compared to the barrel. Therefore, in the outer region where the first forming surface and the first opposing surface face each other, the material can be slowly plasticized, and in the central region where the second forming surface and the second opposing surface face each other, the conveying force of the material toward the communication hole can be improved. For this reason, for example, a material that is difficult to plasticize can be slowly and sufficiently plasticized in the outer region and then injected.

[0015] The plasticizing device according to the fifth aspect of the present invention is characterized in that, in any one of the first to fourth aspects, a coating treatment or a cutting treatment is performed on at least one of the groove forming surface and the opposing surface.

[0016] According to this aspect, a coating treatment or a cutting treatment is performed on at least one of the groove forming surface and the opposing surface. For this reason, for example, the groove forming surface and the opposing surface can be made of the same material, and the types of materials that can be used for manufacturing the flat screw and the barrel can be increased.

[0017] The plasticizing device according to the sixth aspect of the present invention is characterized in that, in the fifth aspect, at least one of diamond coating, chromium coating, or titanium coating is performed on the opposing surface as the coating treatment.

[0018] According to this aspect, at least one of diamond coating, chromium coating, or titanium coating is performed on the opposing surface. For this reason, an opposing surface with a high surface free energy can be formed easily and with high durability.

[0019] In the plasticizing device according to the seventh aspect of the present invention, in the fifth or sixth aspect, the groove forming surface is characterized in that a fluorine coating is applied as the film treatment.

[0020] According to this aspect, the groove forming surface is provided with a fluorine coating. Therefore, a groove forming surface having a particularly low surface free energy can be easily formed.

[0021] In the plasticizing device according to the eighth aspect of the present invention, in any one of the first to seventh aspects, the material is characterized by containing at least one of metal particles and ceramic particles.

[0022] According to this aspect, the material contains at least one of metal particles and ceramic particles. When a material containing at least one of metal particles and ceramic particles is used, the material is particularly likely to adhere to the flat screw side, but even in such a case, it is possible to suppress the material from adhering to the flat screw side and suppress the material from being difficult to be supplied to the communication hole on the barrel side.

[0023] In the plasticizing device according to the ninth aspect of the present invention, in any one of the first to eighth aspects, the difference in surface free energy in a region where the surface free energy of the groove forming surface is lower than the surface free energy of the opposing surface is 4.6 mJ / m 2 or more.

[0024] According to this aspect, the difference in surface free energy in a region where the surface free energy of the groove forming surface is lower than the surface free energy of the opposing surface is 4.6 mJ / m 2 or more. With such a configuration, it is possible to particularly effectively suppress the material from being difficult to be supplied to the communication hole on the barrel side and stably plasticize the material.

[0025] The three-dimensional shaping apparatus according to the tenth aspect of the present invention includes a nozzle that discharges the material plasticized by the plasticizing apparatus according to any one of the first to ninth aspects, and a table that supports the material discharged from the nozzle.

[0026] According to this aspect, a three-dimensional shaped object can be shaped using a stably plasticized material.

[0027] The three-dimensional shaping apparatus according to the eleventh aspect of the present invention includes a nozzle that discharges the material plasticized by the plasticizing apparatus according to any one of the first to ninth aspects, and a fixing portion that fixes a molding die that receives the material discharged from the nozzle.

[0028] According to this aspect, injection molding can be performed using a stably plasticized material.

[0029] <Three-dimensional shaping apparatus (plasticizing apparatus)> Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. First, the overall configuration of a three-dimensional shaping apparatus 100 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. Note that all of the following figures are schematic views, and some constituent members are omitted or simplified. In each figure, the X-axis direction is the horizontal direction, the Y-axis direction is the horizontal direction and is perpendicular to the X-axis direction, and the Z-axis direction is the vertical direction.

[0030] The three-dimensional shaping device 100 includes a control unit 101 that controls the three-dimensional shaping device 100, a shaping unit 110 that generates and discharges a shaping material, a shaping stage 210 that serves as a base for the three-dimensional shaped object, and a moving mechanism 230 that controls the discharge position of the shaping material. Under the control of the control unit 101, the shaping unit 110 discharges the shaping material, which is obtained by melting a solid-state material into a paste state, onto the stage 210. The shaping unit 110 includes a material supply unit 20 that is a supply source of the raw material MR before being converted into the shaping material, a shaping material generation unit 30 that converts the raw material MR into the shaping material, and a discharge unit 60 that discharges the shaping material. That is, the three-dimensional shaping device 100 of the present embodiment can be regarded as a plasticizing device that plasticizes the material. Further, the three-dimensional shaping device 100 includes a plasticizing device composed of the material supply unit 20 and the shaping material generation unit 30, and can also be regarded as a device that discharges the material (shaping material) plasticized by the plasticizing device from the discharge unit 60 to shape a three-dimensional shaped object. Here, "plasticizing" is a concept including melting. In the case of a material having a glass transition point, it means heating the material above the glass transition point to convert it into a state having fluidity. In the case of a material having no glass transition point, it means heating the material above the melting point to convert it into a state having fluidity.

[0031] The material supply unit 20 supplies the raw material MR for generating the shaping material to the shaping material generation unit 30. The material supply unit 20 is composed of, for example, a hopper that houses the raw material MR. The material supply unit 20 has a discharge port downward. The discharge port is connected to the shaping material generation unit 30 via a communication path 22. The raw material MR is input into the material supply unit 20 in the form of pellets, powder, or the like.

[0032] The shaping material generation unit 30 melts the raw material MR supplied from the material supply unit 20 to generate a paste-like shaping material that exhibits fluidity, and guides it to the discharge unit 60. The shaping material generation unit 30 includes a screw case 31, a motor 32, a flat screw 40, and a barrel 50.

[0033] FIG. 2 is a perspective view showing a schematic configuration on the side of the groove forming surface 48 of the flat screw 40. The flat screw 40 shown in FIG. 2 is shown in a state where the positional relationship between the upper surface 47 shown in FIG. 1 and the groove forming surface 48 which is the lower surface is reversed in the vertical direction for easy understanding of the technology. FIG. 3 is a schematic plan view showing the side of the opposing surface 52 which is the upper surface of the barrel 50. The flat screw 40 has a substantially cylindrical shape in which the height in the axial direction, which is the direction along its central axis, is smaller than the diameter. In other words, the flat screw 40 is rotatable with respect to the rotation axis RX along the Z-axis direction, and the length in the rotation axis direction is shorter than the length in the direction perpendicular to the rotation axis direction.

[0034] The flat screw 40 is housed in the screw case 31. The upper surface 47 side of the flat screw 40 is connected to the motor 32, and the flat screw 40 rotates in the screw case 31 by the rotational driving force generated by the motor 32. The motor 32 drives under the control of the control unit 101.

[0035] On the groove forming surface 48 which is a surface of the flat screw 40 intersecting the rotation axis RX, a groove 42 is formed. The communication path 22 of the above-described material supply unit 20 communicates with the groove 42 from the side surface of the flat screw 40. As shown in FIG. 2, in the present embodiment, the groove 42 is formed in three portions separated by the convex portions 43. Note that the number of the grooves 42 is not limited to three, and may be one, or two or more.

[0036] The groove forming surface 48 of the flat screw 40 faces the opposing surface 52 of the barrel 50, and a space is formed between the groove 42 of the groove forming surface 48 of the flat screw 40 and the opposing surface 52 of the barrel 50. The shaping unit 110 supplies the raw material MR from the material supply unit 20 to the material inlet 44 in this space between the flat screw 40 and the barrel 50.

[0037] A heater 58 as a heating unit for heating the raw material MR supplied into the groove 42 of the rotating flat screw 40 is embedded in the barrel 50. However, the heating unit may be provided at a location other than the barrel 50. Further, a plurality of guide grooves 54 are formed on the opposing surface 52, which are connected to the communication hole 56 and extend spirally from the communication hole 56 toward the outer periphery. However, a configuration in which the guide grooves 54 are not formed may also be adopted. The raw material MR supplied into the groove 42 of the flat screw 40 melts in the groove 42 and flows along the groove 42 by the rotation of the flat screw 40, and is guided as a modeling material to the central portion 46 of the flat screw 40. The paste-like modeling material that has flowed into the central portion 46 and exhibits fluidity is supplied to the discharge unit 60 through the communication hole 56 provided at the center of the barrel 50 shown in FIG. 3. Note that in the modeling material, not all types of substances constituting the modeling material need to be melted. The modeling material only needs to be converted into a state having fluidity as a whole by melting at least some of the types of substances constituting the modeling material.

[0038] The discharge unit 60 includes a nozzle 61 that discharges the modeling material, a flow path 65 for the modeling material provided between the flat screw 40 and the nozzle 61, and an opening / closing mechanism 70 that opens and closes the flow path 65. The nozzle 61 is connected to the communication hole 56 of the barrel 50 through the flow path 65. The nozzle 61 discharges the modeling material generated in the modeling material generation unit 30 from the discharge port 62 at the tip toward the stage 210.

[0039] The opening / closing mechanism 70 opens and closes the flow path 65 to control the outflow of the modeling material from the nozzle 61. In the present embodiment, the opening / closing mechanism 70 is configured by a butterfly valve. The opening / closing mechanism 70 includes a drive shaft 72 which is a shaft-like member extending in one direction, a valve body 73 that rotates by the rotation of the drive shaft 72, and a valve drive unit 74 that generates a rotational driving force for the drive shaft 72.

[0040] The drive shaft 72 is attached in the middle of the flow path 65 so as to intersect the flow direction of the shaping material. More specifically, the drive shaft 72 is attached so as to be parallel to the Y-axis direction, which is perpendicular to the flow direction of the shaping material in the flow path 65. The drive shaft 72 is rotatable about a central axis along the Y-axis direction.

[0041] The valve body 73 is a plate-shaped member that rotates within the flow path 65. In the present embodiment, the valve body 73 is formed by machining the portion of the drive shaft 72 disposed within the flow path 65 into a plate shape. When the valve body 73 is viewed in a direction perpendicular to its plate surface, its shape substantially matches the opening shape of the flow path 65 at the portion where the valve body 73 is disposed.

[0042] The valve drive unit 74 rotates the drive shaft 72 under the control of the control unit 101. The valve drive unit 74 is constituted by, for example, a stepping motor. When the drive shaft 72 rotates, the valve body 73 rotates within the flow path 65.

[0043] The state in which the plate surface of the valve body 73 is perpendicular to the flow direction of the shaping material in the flow path 65 is the state in which the flow path 65 is closed. In this state, the inflow of the shaping material from the flow path 65 to the nozzle 61 is blocked, and the outflow of the shaping material from the discharge port 62 is stopped. When the plate surface of the valve body 73 is rotated from this perpendicular state by the rotation of the drive shaft 72, the inflow of the shaping material from the flow path 65 to the nozzle 61 is allowed, and the shaping material with a discharge amount corresponding to the rotation angle of the valve body 73 flows out from the discharge port 62. As shown in FIG. 1, the state along the flow direction of the shaping material in the flow path 65 is the state in which the flow path 65 is fully open. In this state, the discharge amount of the shaping material per unit time from the discharge port 62 is maximized. In this way, the opening and closing mechanism 70 can realize the adjustment of the discharge amount of the shaping material as well as the ON and OFF of the outflow of the shaping material.

[0044] The stage 210 is arranged at a position facing the discharge port 62 of the nozzle 61. In the present embodiment, the surface 211 of the stage 210 facing the discharge port 62 of the nozzle 61 is arranged in the horizontal direction. The three-dimensional shaping device 100 shapes a three-dimensional shaped object by discharging a shaping material from the discharge unit 60 toward the surface 211 of the stage 210 to stack layers.

[0045] The moving mechanism 230 changes the relative position between the stage 210 and the nozzle 61. In the present embodiment, the position of the nozzle 61 is fixed, and the moving mechanism 230 moves the stage 210. The moving mechanism 230 is composed of a three-axis positioner that moves the stage 210 in three axial directions, namely the X-axis direction, the Y-axis direction, and the Z-axis direction, by the driving force of three motors M. The moving mechanism 230 changes the relative positional relationship between the nozzle 61 and the stage 210 under the control of the control unit 101. In this specification, unless otherwise specified, the movement of the nozzle 61 means moving the nozzle 61 relative to the stage 210.

[0046] Note that instead of the configuration in which the moving mechanism 230 moves the stage 210, a configuration may be adopted in which the moving mechanism 230 moves the nozzle 61 relative to the stage 210 with the position of the stage 210 fixed. Also, a configuration in which the moving mechanism 230 moves the stage 210 in the Z-axis direction and moves the nozzle 61 in the X-axis direction and the Y-axis direction, or a configuration in which the moving mechanism 230 moves the stage 210 in the X-axis direction and the Y-axis direction and moves the nozzle 61 in the Z-axis direction may be adopted. Even with these configurations, the relative positional relationship between the nozzle 61 and the stage 210 can be changed.

[0047] The control unit 101 is a control device that controls the operation of the entire three-dimensional shaping apparatus 100. The control unit 101 is composed of a computer including one or a plurality of processors, a main storage device, and an input / output interface for inputting and outputting signals to and from the outside. The control unit 101 exhibits various functions when the processor executes programs and instructions read onto the main storage device. Instead of being composed of a computer, the control unit 101 may be realized by a configuration combining a plurality of circuits for realizing at least a part of each function.

[0048] As described above, the three-dimensional shaping apparatus 100 of this embodiment is rotatable about the rotation axis RX, and includes a flat screw having a groove forming surface 48 with a groove 42 formed at one end in the rotation axis direction, a barrel 50 having an opposing surface 52 opposing the groove forming surface 48 and having a communication hole 56 formed in the opposing surface 52, and a heater 58 for heating the material supplied into the groove 42. Here, the flat screw 40 and the barrel 50, which are the main parts of the three-dimensional shaping apparatus 100 of this embodiment, will be described in more detail below.

[0049] In the flat screw 40 and the barrel 50 of the three-dimensional shaping apparatus 100 of this embodiment, in the region where the groove forming surface 48 and the opposing surface 52 oppose each other, the surface free energy of the groove forming surface 48 is configured to be lower than the surface free energy of the opposing surface 52. Specifically, both the flat screw 40 and the barrel 50 of this embodiment are made of stainless steel (SUS), but the opposing surface 52 is coated with titanium nitride (TiN) having a higher surface free energy than SUS.

[0050] Incidentally, the surface free energy can be measured in accordance with the wettability test method for the substrate glass surface of JIS R 3257 (1999). Here, as Table 1, the contact angles of water and n-hexadecane were measured using Drop Master 500 manufactured by Kyowa Interface Science Co., Ltd., and the surface free energy obtained based on the theoretical formula of Kaelble Uy from the measurement results is shown. In Table 1, polysilazane is NL120A manufactured by Merck KGaA, TaOx is an ALD film formed using (t-butylimide)tris(ethylmethylamino)tantalum: TBTEMT, and SCA is Optool DSX-E manufactured by Daikin Industries, Ltd. Incidentally, the constants of water and n-hexadecane were calculated using the values in Table 2.

[0051]

Table 1

[0052]

Table 2

[0053] As shown in Table 1, since the groove forming surface 48 is made of SUS, the surface free energy of the groove forming surface 48 is 24.3 mJ / m 2 and since the opposing surface 52 is TiN-coated, the surface free energy of the opposing surface 52 is 4.6 mJ / m higher than that of SUS, which is 28.9 mJ / m 2 2 ​It is like this. In Table 1, SUS303 was used as SUS, but other SUS such as SUS440 also has the same values. In a region where the groove forming surface 48 and the opposing surface 52 face each other, like the three-dimensional shaping apparatus 100 of this embodiment, it is preferable to have a region where the surface free energy of the groove forming surface 48 is lower than the surface free energy of the opposing surface 52. By adopting such a configuration, in this region, the material being plasticized and the plasticized material are less likely to stick to the flat screw 40 compared to the barrel 50, and the material is more likely to move toward the communication hole 56. And by adopting such a configuration, it is possible to suppress the material from being less likely to be supplied to the communication hole 56 on the barrel 50 side, and the material can be stably plasticized.

[0054] Also, as described above, in the three-dimensional shaping apparatus 100 of this embodiment, the difference between the surface free energy of the groove forming surface 48 and the surface free energy of the opposing surface 52 is 4.6 mJ / m 2 That is. In this way, the difference in surface free energy in the region where the surface free energy of the groove forming surface 48 is lower than the surface free energy of the opposing surface 52 is 4.6 mJ / m 2 or more is preferable. By adopting such a configuration, it is possible to particularly effectively suppress the material from being less likely to be supplied to the communication hole 56 on the barrel 50 side, and the material can be stably plasticized.

[0055] Also, as described above, in the three-dimensional shaping apparatus 100 of this embodiment, the opposing surface 52 is subjected to a film treatment. It is preferable that at least one of the groove forming surface 48 and the opposing surface 52 is subjected to a film treatment, or at least one of the groove forming surface 48 and the opposing surface 52 is subjected to a cutting treatment. By adopting such a configuration, for example, the groove forming surface 48 and the opposing surface 52 can be made of the same material, and the types of materials that can be used for manufacturing the flat screw 40 and the barrel 50 can be increased. Here, the "cutting treatment" includes, for example, knurling and surfaces treated with chemicals.

[0056] Also, as described above, in the three-dimensional shaping apparatus 100 of the present embodiment, the opposing surface 52 is titanium-coated with TiN. Preferred coating treatments for the opposing surface 52 include, in addition to titanium coating, diamond coating, chromium coating, and the like. By applying at least any one of diamond coating, chromium coating, or titanium coating to the opposing surface 52, the opposing surface 52 with a high surface free energy can be formed easily and with high durability.

[0057] On the other hand, instead of applying a coating treatment or a cutting treatment to the opposing surface 52, or in addition to applying a coating treatment or a cutting treatment to the opposing surface 52, it is also possible to apply a coating treatment or a cutting treatment to the groove forming surface 48. Here, applying a fluorine coating is mentioned as a preferred coating treatment for the groove forming surface 48. By applying a fluorine coating to the groove forming surface 48, the groove forming surface 48 with a particularly low surface free energy can be easily formed.

[0058] Here, as shown in FIG. 2, the groove forming surface 48 has a first forming surface 48A in a region located outside when viewed from the Z-axis direction, and a second forming surface 48B in a region located closer to the center than the first forming surface 48A when viewed from the Z-axis direction. Also, as shown in FIG. 3, the opposing surface 52 is a region located outside when viewed from the Z-axis direction, and a first opposing surface 52A in a region opposing the first forming surface 48A, and a second opposing surface 52B in a region located closer to the center than the first opposing surface 52A when viewed from the Z-axis direction and opposing the second forming surface 48B.

[0059] And in the three-dimensional shaping apparatus 100 of the present embodiment, both the first forming surface 48A and the second forming surface 48B of the groove forming surface 48 are made of SUS that has not been subjected to film treatment and cutting treatment, and both the first opposing surface 52A and the second opposing surface 52B of the opposing surface 52 are subjected to titanium coating with TiN. That is, in the three-dimensional shaping apparatus 100 of the present embodiment, the surface free energy of the first forming surface 48A is lower than the surface free energy of the first opposing surface 52A, and the surface free energy of the second forming surface 48B is lower than the surface free energy of the second opposing surface 52B. By adopting such a configuration, in the entire region where the groove forming surface 48 and the opposing surface 52 face each other, that is, in both the outer region where the first forming surface 48A and the first opposing surface 52A face each other and the central region where the second forming surface 48B and the second opposing surface 52B face each other, the material is less likely to adhere to the flat screw 40 compared to the barrel 50. Therefore, the conveying force of the material toward the communication hole 56 can be improved in the entire region where the groove forming surface 48 and the opposing surface 52 face each other. For this reason, for example, when the nozzle 61 has a small diameter, the plasticized material can be injected from the nozzle 61 at a high pressure.

[0060] However, the present invention is not limited to the configuration in which the surface free energy relationship of the first forming surface 48A and the second forming surface 48B and the first opposing surface 52A and the second opposing surface 52B is as described above. For example, a configuration can be adopted in which the surface free energy of the first forming surface 48A is lower than the surface free energy of the first opposing surface 52A, and the surface free energy of the second forming surface 48B is higher than the surface free energy of the second opposing surface 52B. By adopting such a configuration, in the outer region where the first forming surface 48A and the first opposing surface 52A face each other, the material is less likely to adhere to the flat screw 40 compared to the barrel 50. Therefore, the conveying force of the material toward the communication hole 56 can be improved in the outer region where the first forming surface 48A and the first opposing surface 52A face each other, and the material can be plastified slowly by deliberately reducing the conveying force in the central region where the second forming surface 48B and the second opposing surface 52B face each other. For this reason, for example, a large-diameter nozzle 61 can be used as the nozzle 61, and the plasticized material can be injected with a large injection amount.

[0061] Further, for example, the surface free energy of the first forming surface 48A can be made higher than the surface free energy of the first opposing surface 52A, and the surface free energy of the second forming surface 48B can be made lower than the surface free energy of the second opposing surface 52B. With such a configuration, in the region on the central side where the second forming surface 48B and the second opposing surface 52B face each other, it becomes more difficult for the material to adhere to the flat screw 40 compared to the barrel 50. Therefore, by deliberately reducing the conveying force in the outer region where the first forming surface 48A and the first opposing surface 52A face each other, the material can be plastified thoroughly, and in the region on the central side where the second forming surface 48B and the second opposing surface 52B face each other, the conveying force of the material toward the communication hole 56 can be improved. For this reason, for example, a material that is difficult to plastify can be plastified thoroughly in the outer region and then injected.

[0062] In the three-dimensional shaping apparatus 100 of this embodiment, as the material, one containing at least either metal particles or ceramic particles can be used. When a material containing at least either metal particles or ceramic particles is used, the material is particularly likely to adhere to the flat screw 40 side, but with the above-described configuration, even in such a case, it is possible to suppress the material from adhering to the flat screw 40 side and suppress the material from being less likely to be supplied to the communication hole 56 on the barrel 50 side. In addition to materials containing at least either metal particles or ceramic particles, it is also possible to use materials containing biodegradable plastics such as polylactic acid and paraffin, cellulose, and composites thereof.

[0063] <Injection Molding Apparatus (Plasticizing Apparatus)> Next, the overall configuration of the injection molding apparatus 310 according to an embodiment of the present invention will be described with reference to FIG. 4. Note that all the following figures are schematic diagrams, and some constituent members are omitted or simplified. The injection molding apparatus 310 of the present embodiment includes a flat screw 321 having a groove forming surface similar to the flat screw 40 of the three-dimensional shaping apparatus 100, a barrel 325 having an opposing surface similar to the barrel 50 of the three-dimensional shaping apparatus 100, and a heater 324 as a heating unit. That is, the injection molding apparatus 310 of the present embodiment can be regarded as a plasticizing apparatus for plasticizing a material. Further, the injection molding apparatus 310 can also be regarded as an apparatus including a plasticizing apparatus and capable of performing injection molding using the material plasticized by the plasticizing apparatus.

[0064] FIG. 4 schematically shows a cross-section obtained by cutting the injection molding apparatus 310 along the vertical direction in a cross-section including the axis AX of the flow path 450 formed in the hot runner 400. Note that the axis AX corresponds to the rotation axis of the flat screw 321. In FIG. 4, U-axis, V-axis, and W-axis that are orthogonal to each other are shown. The injection molding apparatus 310 injects the plasticized material into a mold to produce a molded product. The injection molding apparatus 310 includes a material generation unit 320, an injection unit 330, a mold 340, a fixing unit 360 for fixing the mold 340, a mold opening and closing unit 350, and a control unit 390.

[0065] The material generation unit 320 generates a molding material having fluidity by plasticizing at least a part of the solid material supplied from a hopper (not shown) disposed vertically above, and supplies it to the injection unit 330 side. Such solid material is introduced into the hopper in various granular forms such as pellets and powders. The material generation unit 320 includes a flat screw 321, a barrel 325, and a drive motor 329.

[0066] The flat screw 321 has a substantially cylindrical outer shape with a length along the axis AX smaller than the diameter, similar to the flat screw 40 of the three-dimensional shaping apparatus 100. The flat screw 321 is arranged such that the axis AX of the flow path 450 formed in the hot runner 400 coincides with the axis AX of the flat screw 321. A groove 322 is formed on the groove forming surface 311 of the flat screw 321, and a material inlet 23 is formed on the outer peripheral surface of the flat screw 321. The groove 322 is continuous up to the material inlet 323. The material inlet 323 receives the solid material supplied from the hopper.

[0067] The barrel 325 has a substantially disc-shaped outer appearance and is arranged to face the groove forming surface 311 of the flat screw 321 at the opposing surface 327. A heater 324 as a heating part for heating the material is embedded in the barrel 325. However, the heating part may be provided at a location other than the barrel 325. Further, a through hole 326 penetrating along the axis AX is formed in the barrel 325. The through hole 326 functions as a flow path for guiding the molding material to the hot runner 400. An injection cylinder 332 penetrating along an axis orthogonal to the axis AX is formed in the barrel 325. The injection cylinder 332 constitutes a part of the injection part 330 and communicates with the through hole 326.

[0068] The drive motor 329 is connected to the end face of the flat screw 321 on the side opposite to the side facing the barrel 325. The drive motor 329 is driven in response to a command from the control unit 390 and rotates the flat screw 321 with the axis AX as the rotation axis.

[0069] At least a part of the material supplied from the material inlet 323 is heated by the heater 324 provided in the barrel 325 in the groove 322 of the flat screw 321, while being plasticized and increased in fluidity by the rotation of the flat screw 321, and is guided to the through hole 326. Compression and degassing of the molding material are also achieved by the rotation of the flat screw 321.

[0070] The injection unit 330 measures the molding material supplied from the material generation unit 320 and injects it into the cavity 349 formed in the movable mold 348 of the mold 340. The injection unit 330 includes an injection cylinder 332, an injection plunger 334, a check valve 336, an injection motor 338, and a hot runner 400.

[0071] The injection cylinder 332 is formed in a substantially cylindrical shape inside the barrel 325 and communicates with the through hole 326. The injection plunger 334 is slidably disposed within the injection cylinder 332. When the injection plunger 334 slides, the molding material in the through hole 326 is drawn into the injection cylinder 332 and measured, and the molding material in the injection cylinder 332 is pumped toward the hot runner 400 side and injected into the cavity 349. The check valve 336 is disposed within the through hole 326 on the flat screw 321 side rather than at the communication location between the injection cylinder 332 and the through hole 326. The check valve 336 allows the flow of the molding material from the flat screw 321 side to the hot runner 400 side while suppressing the backflow of the molding material from the hot runner 400 side to the flat screw 321 side. The injection motor 338 is driven in response to a command from the control unit 390 to slide the injection plunger 334 within the injection cylinder 332. The sliding speed and sliding amount of the injection plunger 334 are preset according to the type of the molding material, the size of the cavity 349, and the like. The hot runner 400 has a function of guiding the molding material to the cavity 349 in a heated state.

[0072] The mold 340 includes a fixed mold 341 and a movable mold 348. Inside the fixed mold 341, a hot runner mounting hole 342 penetrating along the axis AX is formed. The hot runner 400 is disposed in the hot runner mounting hole 342.

[0073] The hot runner mounting hole 342 is formed such that its inner diameter gradually decreases in order from the material generation part 320 side. The end of the hot runner mounting hole 342 on the side opposite to the material generation part 320 side functions as a gate opening 345 through which the molding material flows in. The gate opening 345 is configured as a substantially circular hole.

[0074] The movable mold 348 is disposed opposite to the fixed mold 341. The movable mold 348 abuts against the fixed mold 341 during mold closing and clamping including when injecting and cooling the molding material, and separates from the fixed mold 341 during mold opening including when ejecting the molded product. When the fixed mold 341 and the movable mold 348 abut against each other, a cavity 349 communicating with the gate opening 345 is formed between the fixed mold 341 and the movable mold 348. The cavity 349 is pre-designed to have the shape of the molded product to be formed by injection molding. In this embodiment, the cavity 349 is formed directly continuous with the gate opening 345, but may also be formed continuous via a runner.

[0075] In this embodiment, the mold 340 is formed of an Invar material. The Invar material has the property of having an extremely small coefficient of thermal expansion. Further, a refrigerant flow path (not shown) is formed in the mold 340. By flowing a refrigerant such as cooling water through the refrigerant flow path, the temperature of the mold 340 is kept lower than the melting temperature of the resin, and the molding material injected into the cavity 349 is cooled and cured. The refrigerant is flowed both during mold clamping and mold opening. The cooling and curing of the molding material may be realized using any cooling means such as a Peltier element instead of flowing the refrigerant through the refrigerant flow path.

[0076] The mold opening / closing part 350 opens and closes the fixed mold 341 and the movable mold 348. The mold opening / closing part 350 includes a mold opening / closing motor 358 and an ejection pin 359. The mold opening / closing motor 358 is driven in response to a command from the control unit 390 to move the movable mold 348 along the axis AX. Thereby, mold closing, mold clamping, and mold opening of the molding die 340 are realized. The ejection pin 359 is disposed at a position communicating with the cavity 349. The ejection pin 359 ejects the molded product when the mold is opened, thereby demolding the molded product.

[0077] The control unit 390 controls the operation of the entire injection molding apparatus 310 to execute injection molding. The control unit 390 is constituted by a computer having a CPU, a storage device, and an input / output interface. The CPU executes a control program stored in advance in the storage device. The control unit 390 controls the temperature of the heater 130 embedded in the hot runner 400 to adjust the temperature of the hot runner 400. The user of the injection molding apparatus 310 can perform various settings regarding injection molding conditions by operating a controller which is the input / output interface of the control unit 390.

[0078] The hot runner 400 guides the molding material supplied from the injection part 330 to the gate opening 345 in a heated state. The hot runner 400 is disposed in the hot runner mounting hole 342 of the fixed mold 341. Note that the injection molding apparatus 310 may be provided with a nozzle in which a flow path for guiding the molding material to the gate opening 345 is formed instead of the hot runner 400.

[0079] As described above, the injection molding apparatus 310 of the present embodiment includes a flat screw 321 having a groove forming surface similar to that of the flat screw 40 of the three-dimensional modeling apparatus 100, a barrel 325 having an opposing surface similar to that of the barrel 50 of the three-dimensional modeling apparatus 100, and a heater 324 as a heating unit. Therefore, it has the same characteristics as those of the plasticizing device described in the three-dimensional modeling apparatus 100. Further, although the injection molding apparatus 310 of the present embodiment has the overall configuration as described above, it is not limited to such a configuration as long as it has the above characteristics as a plasticizing device.

[0080] The present invention is not limited to the above-described embodiments, and can be realized in various configurations without departing from the gist thereof. The technical features in the embodiments corresponding to the technical features in each form described in the summary of the invention can be appropriately replaced or combined in order to solve some or all of the above-described problems or to achieve some or all of the above-described effects. Further, if the technical feature is not described as essential in this specification, it can be appropriately deleted.

Explanation of Signs

[0081] 20…Material supply section, 22…Communication path, 30…Molding material generation section, 31…Screw case, 32…Motor, 40…Flat screw, 42…Groove, 43…Convex part, 44…Material inlet, 46…Central part, 47…Upper surface, 48…Groove formation surface, 50…Barrel, 52…Opposing surface, 54…Guide groove, 56…Communication hole, 58…Heater (heating section), 60…Discharge section, 61…Nozzle, 62…Discharge port, 65…Flow path, 70…Opening / closing mechanism, 72…Drive shaft, 73…Valve body, 74…Valve drive section, 100…Three-dimensional molding device (plasticizing device), 101…Control section, 110…Molding section, 210…Stage, 211…Surface, 230…Moving mechanism, 310…Injection molding device, 311…Groove formation surface, 320…Material generation section, 321…Flat screw, 322…Groove, 23…Material inlet, 324…Heater (heating section), 325…Barrel, 326…Through hole, 327…Opposing surface, 329…Drive motor, 330…Injection section, 332…Injection cylinder, 334…Injection plunger, 336…Check valve, 338…Injection motor, 340…Mold, 341…Fixed mold, 342…Hot runner attachment hole, 345…Gate opening, 348…Movable mold, 349…Cavity, 350…Mold opening / closing section, 358…Mold opening / closing motor, 359…Extrusion pin, 360…Fixed section, 390…Control section, 400…Hot runner, 450…Flow path, AX…Axis (rotation axis), M…Motor, MR…Raw material, RX…Rotation axis

Claims

1. A flat screw that is rotatable about a rotation axis, has a groove-forming surface on which a groove is formed, and has a length in a direction along the rotation axis shorter than a length in a direction perpendicular to the direction along the rotation axis, a barrel having an opposing surface that faces the groove-forming surface and having a communication hole formed in the opposing surface, a heating unit that heats a material supplied into the groove, comprising: The groove-forming surface includes a region having a surface free energy lower than that of the opposing surface, and the plasticizing device for the material is characterized by this.

2. In the plasticizing device according to Claim 1, the groove-forming surface has a first forming surface and a second forming surface located closer to the center than the first forming surface, the opposing surface has a first opposing surface that faces the first forming surface and a second opposing surface that faces the second forming surface and is located closer to the center than the first opposing surface, the surface free energy of the first forming surface is lower than the surface free energy of the first opposing surface, and the surface free energy of the second forming surface is lower than the surface free energy of the second opposing surface, and the plasticizing device is characterized by this.

3. In the plasticizing device according to Claim 1, the groove-forming surface has a first forming surface and a second forming surface located closer to the center than the first forming surface, the opposing surface has a first opposing surface that faces the first forming surface and a second opposing surface that faces the second forming surface and is located closer to the center than the first opposing surface, the surface free energy of the first forming surface is lower than the surface free energy of the first opposing surface, and the surface free energy of the second forming surface is higher than the surface free energy of the second opposing surface, and the plasticizing device is characterized by this.

4. In the plasticizing device according to Claim 1, the groove-forming surface has a first forming surface and a second forming surface located closer to the center than the first forming surface, the opposing surface has a first opposing surface that faces the first forming surface and a second opposing surface that faces the second forming surface and is located closer to the center than the first opposing surface, the surface free energy of the first forming surface is higher than the surface free energy of the first opposing surface, and the surface free energy of the second forming surface is lower than the surface free energy of the second opposing surface, and the plasticizing device is characterized by this.

5. In the plasticizing device according to any one of Claims 1 to 4, A plasticizing device, characterized in that at least one of the groove-forming surface and the opposing surface is subjected to a coating treatment or a cutting treatment. **Claim 6** In the plasticizing device according to claim 5, the opposing surface is characterized in that at least one of diamond coating, chromium coating or titanium coating is applied as the coating treatment. **Claim 7** In the plasticizing device according to claim 5 or 6, the groove-forming surface is characterized in that a fluorine coating is applied as the coating treatment. **Claim 8** In the plasticizing device according to any one of claims 1 to 7, the material is characterized by containing at least one of metal particles and ceramic particles. **Claim 9** In the plasticizing device according to any one of claims 1 to 8, The difference in surface free energy in a region where the surface free energy of the groove forming surface is lower than the surface free energy of the opposing surface is 4.6 mJ / m ２ The plasticizing device is characterized in that it is as described above. **Claim 10** A three-dimensional shaping device, comprising: a nozzle for discharging the material plasticized by the plasticizing device according to any one of claims 1 to 9; and a table for supporting the material discharged from the nozzle. **Claim 11** An injection molding device, comprising: a nozzle for discharging the material plasticized by the plasticizing device according to any one of claims 1 to 9; and a fixing portion for fixing a molding die for receiving the material discharged from the nozzle.

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