Material dispensing device

Abstract

Miniaturize the material dispensing device. [Solution] The material dispensing device is a suction extrusion unit comprising a plasticizing unit that generates a plasticizable material by plasticizing the material, a cylinder connected to the plasticizing unit, a plunger, and a drive unit that moves the plunger, and further comprising a suction extrusion unit that sucks the plasticizable material into the cylinder or pushes the plasticizable material out from inside the cylinder by the movement of the plunger. The drive unit comprises a screw shaft, a nut, and a gear, the nut is fixed in the material dispensing device, the screw shaft passes through the nut and is connected to the plunger, the gear has the central axis of the screw shaft as its central axis and rotates the screw shaft by receiving rotational force from the outside, and the plunger is moved by the movement of the screw shaft relative to the nut caused by the rotation of the screw shaft, which is movement along the direction of the central axis.

Description

Technical Field

[0001] The present disclosure relates to a material ejection device.

Background Art

[0002] Conventionally, there exists a material ejection device that ejects a modeling material into a mold. The material ejection device of Patent Document 1 includes a cylinder, a plunger, and a plunger drive unit. When the plunger drive unit moves the plunger in the forward direction, the modeling material is suctioned into the cylinder. When the plunger drive unit moves the plunger in the reverse direction, the modeling material in the cylinder is sent out to the flow path.

[0003] The plunger drive unit includes a motor and a ball screw. The ball screw includes a screw shaft and a nut. The screw shaft is arranged parallel to the plunger. The screw shaft penetrates through the nut. The nut is connected to one end of the plunger. When the screw shaft is rotated by the motor, the nut moves along the screw shaft. Together with the nut, the plunger connected to the nut moves. As a result, the modeling material is suctioned into the cylinder, or the modeling material in the cylinder is sent out to the flow path.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the material dispensing device described in Patent Document 1, when the molding material in the cylinder is discharged into the flow path, the nut connected to the plunger moves along the screw shaft. Therefore, a space large enough for the nut, which is inserted through the screw shaft, to move along the screw shaft must be provided within the material dispensing device. Consequently, it was difficult to miniaturize the material dispensing device described in Patent Document 1. [Means for solving the problem]

[0006] This disclosure is made to solve at least some of the problems described above and can be implemented in the following forms.

[0007] According to one embodiment of the present disclosure, a material dispensing device for dispensing a plastic material is provided. The material dispensing device comprises a plasticizing unit that generates a plasticizable material by plasticizing a solid material, a cylinder connected to the plasticizing unit, a plunger, and a drive unit that moves the plunger relative to the cylinder, and a suction extrusion unit that sucks the plasticizable material into the cylinder or pushes the plasticizable material out of the cylinder by the movement of the plunger. The drive unit comprises a screw shaft, a nut, and a gear, the nut being fixed in the material dispensing device, the screw shaft passing through the nut and being connected to the plunger, the gear having the central axis of the screw shaft as its central axis and receiving rotational force from the outside to rotate the screw shaft, and the plunger being moved by the movement of the screw shaft relative to the nut, which is caused by the rotation of the screw shaft and is a movement along the direction of the central axis. [Brief explanation of the drawing]

[0008] [Figure 1] This is a plan view of the injection molding apparatus 10 in the embodiment. [Figure 2] This is a perspective view of the injection molding apparatus 10. [Figure 3] This is a cross-sectional view of the injection unit 100. [Figure 4] This is a perspective view of the flat screw 111. [Figure 5] This is a plan view of barrel 112. [Figure 6] This is a perspective view showing the drive unit 123 with a portion removed. [Figure 7] This is a cross-sectional view of the drive unit 123. [Figure 8] This is a perspective view showing the gear 123gr and the screw shaft 123ss. [Figure 9] This is a front view showing the gear 123gr and the screw shaft 123ss. [Figure 10] This is a perspective view showing the gear 123gr and the screw shaft 123ss. [Figure 11] This is a front view showing the gear 123gr and the screw shaft 123ss. [Figure 12] This is a cross-sectional view showing the state in which the screw shaft 123ss is moved as far as possible in the positive X-axis direction relative to the gear 123gr. [Figure 13] This is a cross-sectional view showing the state in which the screw shaft 123ss is moved to its maximum extent in the negative direction of the X-axis relative to the gear 123gr. [Modes for carrying out the invention]

[0009] A. Embodiments: Figure 1 is a plan view of the injection molding apparatus 10 in an embodiment. Figure 2 is a perspective view of the injection molding apparatus 10. In Figure 1, arrows are shown indicating the mutually orthogonal X, Y, and Z axes. The positive direction of the Z axis is vertically upward. The X, Y, and Z axes constitute a left-handed system. The X, Y, and Z axes shown in Figures 2 and later correspond to the X, Y, and Z axes shown in Figure 1.

[0010] The injection molding apparatus 10 is supplied with a solid thermoplastic resin and manufactures molded products from the thermoplastic resin. The injection molding apparatus 10 comprises an injection unit 100, a clamping device 130, a mold 160, and a control unit 500. The injection molding apparatus 10 injects the molding material from the injection unit 100 into the mold 160 to form a molded product (see the middle left of Figure 2).

[0011] The control unit 500 controls the operation of the injection unit 100 and the mold clamping device 130 (see upper center of Figure 1). The control unit 500 is configured as a computer equipped with a CPU (Central Processing Unit) and memory. The control unit 500 controls each part of the injection molding apparatus 10 by having the CPU execute a program stored in the memory. The control unit 500 may also be configured as a circuit.

[0012] A metal mold 160 is mounted on the clamping device 130 (see the lower left of Figure 1 and the middle right of Figure 2). The mold 160 is not limited to metal; it may also be made of resin or ceramic. The metal mold 160 is called a mold. The mold 160 includes a fixed mold 161 and a movable mold 162. The fixed mold 161 is a mold fixed to the injection unit 100, and the movable mold 162 is a mold that can move forward and backward in the clamping direction relative to the fixed mold 161 by the clamping device 130. The clamping direction is the negative direction of the Y axis.

[0013] The mold clamping device 130 has the function of opening and closing the fixed mold 161 and the movable mold 162 (see the lower right of Figure 1 and the lower right of Figure 2). Under the control of the control unit 500, the mold clamping device 130 rotates a ball screw 132 by driving a mold drive unit 131, which is composed of a motor, and moves the movable mold 162, which is coupled to the ball screw 132, relative to the fixed mold 161 to open and close the molding mold 160.

[0014] The injection unit 100 discharges a plasticizable material (see the lower left part in the lower part of FIG. 1 and the lower left part in the middle part of FIG. 2). A hopper 30 into which the material for the molded product is loaded is connected to the injection unit 100 (see the lower left part in the lower part of FIG. 1 and the upper left part in the upper part of FIG. 2). As the material for the molded product, for example, a thermoplastic resin formed in pellet form is used. As the thermoplastic resin, for example, ABS (acrylonitrile butadiene styrene), PC (polycarbonate), POM (polyacetal), PP (polypropylene), PBT (polybutylene terephthalate), etc. are used. The supply of the material to the injection unit 100 is not limited to the hopper 30, and may be performed, for example, by a tube through which the material is pressure-fed.

[0015] The injection unit 100 plasticizes at least a part of the material supplied from the hopper 30 to generate a molding material, and injects the molding material into a cavity partitioned between a fixed mold 161 and a movable mold 162. In this specification, the molding material is also referred to as a plasticized material. In this specification, "plasticization" is a concept including melting, and is to change from a solid state to a state having fluidity. Specifically, in the case of a material in which glass transition occurs, "plasticization" is to make the temperature of the material equal to or higher than the glass transition point. In the case of a material in which glass transition does not occur, "plasticization" is to make the temperature of the material equal to or higher than the melting point.

[0016] FIG. 3 is a cross-sectional view of the injection unit 100. The injection unit 100 of the present embodiment includes a plasticizing device 110 (see the lower left part in the middle part of FIG. 3). The plasticizing device 110 has a flat screw 111, a barrel 112, a heater 113 as a heating unit, a nozzle 114, and a suction and extrusion unit 120.

[0017] The flat screw 111 is housed in the housing 101 (see the middle left of Figure 3). The flat screw 111 is also called a rotor or simply a screw. The flat screw 111 rotates within the housing 101 around the drive shaft 119 of the drive motor 118 by the drive motor 118. The central axis RX, which is the rotation center of the flat screw 111, coincides with the center of the drive shaft 119 of the drive motor 118 in the XZ plane. In this embodiment, the axial directions of the drive shaft 119 and the central axis RX are parallel to the Y-axis direction. The rotation of the flat screw 111 by the drive motor 118 is controlled by the control unit 500 (see the upper right of Figure 1). The flat screw 111 may also be driven by the drive motor 118 via a reduction gear.

[0018] A communication hole 115 is formed in the center of the barrel 112 (see the middle left of Figure 3). The communication hole 115 communicates with the flow path 116. The plasticizing material flows through the flow path 116. The cylinder 121 and nozzle 114, which will be described later, are connected to the flow path 116. The flow path 116 communicates with the nozzle opening 114o of the nozzle 114 (see the lower center of Figure 3). A check valve 124 is provided in the flow path 116 upstream of the cylinder 121 (see the middle left of Figure 3). The check valve 124 prevents the plasticizing material from flowing back from the nozzle 114 side to the flat screw 111 side.

[0019] The heater 113 heats the barrel 112 and the cylinder 121 (see the middle left of Figure 3). Heating by the heater 113 is controlled by the control unit 500. In the example in Figure 3, the heater 113 is positioned on the negative Y-axis side of the cylinder 121. However, the heater 113 may be positioned on the positive Z-axis side or the negative Z-axis side of the cylinder. Alternatively, multiple heaters 113 may be positioned so as to sandwich the cylinder 121 from both the positive Z-axis side and the negative Z-axis side.

[0020] The nozzle 114 has a nozzle opening 114o (see the lower left of Figure 3). The nozzle 114 dispenses the plasticizing material from the nozzle opening 114o. The plasticizing material dispensed from the nozzle opening 114o flows into the cavity of the mold 160.

[0021] Figure 4 is a perspective view of the flat screw 111. The flat screw 111 has a substantially cylindrical external shape. In the substantially cylindrical external shape of the flat screw 111, the height in the direction along the central axis RX is smaller than the diameter. On the groove-forming surface 201 of the flat screw 111 facing the barrel 112, a plurality of spiral grooves 202 are formed around the central part 205. Each groove 202 communicates with a material input port 203 formed on the side of the flat screw 111. Material supplied from the hopper 30 is supplied to the grooves 202 through the material input port 203. The plurality of grooves 202 are formed by being separated by protruding ridges 204. Figure 4 shows an example in which three grooves 202 are formed. However, the number of grooves 202 may be one, two, or four or more. Furthermore, the groove 202 is not limited to a spiral shape; it may also have a helical or involute curve shape, or it may have a shape that extends in an arc from the central part 205 toward the outer circumference.

[0022] Figure 5 is a plan view of the barrel 112. The barrel 112 has an opposing surface 212. The opposing surface 212 of the barrel 112 faces the groove-forming surface 201 of the flat screw 111 in the direction along the drive shaft 119 (see the middle left of Figure 3). A communication hole 115 communicating with the flow path 116 is formed in the center of the opposing surface 212. Multiple guide grooves 211 are formed on the opposing surface 212, connected to the communication hole 115 and extending spirally from the communication hole 115 toward the outer circumference. Note that the barrel 112 does not necessarily have to have guide grooves 211. Also, the guide grooves 211 do not necessarily have to be connected to the communication hole 115.

[0023] The material supplied to the groove 202 of the flat screw 111 flows along the groove 202 and guide groove 211 as the flat screw 111 rotates and the heater 113 heats it, causing it to plasticize between the flat screw 111 and the barrel 112. The plasticized material is guided to the central part 205 of the flat screw 111 (see the middle section of Figure 4). The material that flows into the central part 205 flows out into the flow path 116 through a communication hole 115 located in the center of the barrel 112 (see the middle section of Figure 5 and the left section of the middle section of Figure 3). In this specification, the space between the groove-forming surface 201 of the flat screw 111 and the opposing surface of the barrel 112 is also considered part of the flow path 116. In other words, material or plasticized material passes through the flow path 116. The flat screw 111, barrel 112, and heater 113 generate plasticized material by plasticizing the solid material.

[0024] The suction extrusion unit 120 draws the plasticizing material between the flat screw 111 and the barrel 112 through the flow path 116 and pushes the drawn plasticizing material into the flow path 116 (see upper left of Figure 1, upper center of Figure 2, and right of Figure 3). The plasticizing material pushed into the flow path 116 flows into the cavity of the mold 160 through the nozzle 114. The suction extrusion unit 120 comprises a cylinder 121, a plunger 122, and a drive unit 123.

[0025] Cylinder 121 is connected to the flow path 116 (see lower left of Figure 3). Cylinder 121 is connected to the flat screw 111 and barrel 112, which are part of the plasticizer, via the flow path 116. Part of the plunger 122 is located inside cylinder 121, and the other part of the plunger 122 is located outside cylinder 121.

[0026] The drive unit 123 moves the plunger 122 relative to the cylinder 121 (see the right side of Figure 3). The movement of the plunger 122 relative to the cylinder 121 causes the plasticizing material to be drawn into the cylinder 121 or pushed out from the cylinder 121 (see arrow RA in Figure 3).

[0027] Figure 6 is a perspective view showing a state in which a portion of the drive unit 123 has been removed. Figure 6 shows a state in which a portion of the drive unit 123 has been removed by a horizontal plane passing through the central axis CA of the screw shaft 123ss and a plane passing through the central axis CA of the screw shaft 123ss and perpendicular to the horizontal plane.

[0028] Figure 7 is a cross-sectional view of the drive unit 123. Figure 7 shows a state in which a portion of the drive unit 123 has been removed by a horizontal plane passing through the central axis CA of the screw shaft 123ss. The drive unit 123 comprises an electric motor 123mt, a toothed pulley 123p1, a toothed belt 123bt, a toothed pulley 123p2, an eccentric shaft 123es, a ring gear 123rg, a gear 123gr, a transmission structure 123tr, a screw shaft 123ss, and a nut 123nt.

[0029] The electric motor 123mt is supplied with power and outputs rotational force (see upper center of Figure 6 and upper center of Figure 7). The toothed pulley 123p1 is fixed to the output shaft of the electric motor 123mt (see upper right of Figure 7). The toothed pulley 123p1 rotates along with the rotation of the output shaft of the electric motor 123mt.

[0030] The toothed pulley 123p2 is fixed to the eccentric shaft 123es (see the lower right of Figure 6 and the lower right of Figure 7). The toothed belt 123bt connects the toothed pulleys 123p1 and 123p2 (see the right side of Figure 7). The rotational force of the toothed pulley 123p1 is transmitted to the toothed pulley 123p2 via the toothed belt 123bt. The eccentric shaft 123es rotates along with the rotation of the toothed pulley 123p2 (see the lower right of Figure 6 and the lower right of Figure 7). The central axis of the eccentric shaft 123es is offset from the central axis CA of the gear 123gr and the screw shaft 123ss.

[0031] The ring gear 123rg rotates with the rotation of the eccentric shaft 123es (see the lower center of Figure 6 and the lower right of Figure 7). The ring gear 123rg has an annular structure. The central axis of the ring gear 123rg is offset from the central axis CA of the gear 123gr and the screw shaft 123ss. The ring gear 123rg has multiple protrusions, i.e., multiple teeth, on the inside of the ring. The gear 123gr is arranged inside the ring of the ring gear 123rg.

[0032] The gear 123gr has the central axis CA of the screw shaft 123ss as its central axis (see the lower center of Figure 6 and the lower right of Figure 7). The gear 123gr receives rotational force from an external source and rotates the screw shaft 123ss. Specifically, the gear 123gr receives rotational force from the ring gear 123rg. The gear 123gr has a through hole 123grh and multiple teeth.

[0033] Multiple teeth are provided on the outer circumference of gear 123gr. Gear 123gr is a cycloidal gear. Some of the multiple teeth of gear 123gr mesh with some of the multiple teeth of ring gear 123rg. When ring gear 123rg is rotated by electric motor 123mt via toothed pulley 123p1, toothed belt 123bt, toothed pulley 123p2, and eccentric shaft 123es, gear 123gr rotates at a lower rotational speed than ring gear 123rg due to the meshing of the teeth.

[0034] The through hole 123gr is provided along the direction of the central axis CA of the gear 123gr.

[0035] Figure 8 is a perspective view showing the gear 123gr and the screw shaft 123ss. Figure 9 is a front view showing the gear 123gr and the screw shaft 123ss. The screw shaft 123ss passes through a through hole 123grh so that it can slide along the direction of the central axis CA (see Figure 8).

[0036] The screw shaft 123ss has a non-circular outer shape at the portion 123sst through which it penetrates the gear 123gr. In this embodiment, the screw shaft 123ss has a substantially regular polygonal outer shape at the portion 123sst through which it penetrates the gear 123gr (see the lower center of Figure 8). In this specification, "substantially regular polygonal" means a shape in which 80% or more of the outer contour coincides with a regular polygon. In this embodiment, the outer shape of the portion 123sst of the screw shaft 123ss that penetrates the gear 123gr is substantially square. Note that "outer shape" refers to the outer shape in a cross-section perpendicular to the central axis CA. That is, in this embodiment, the portion 123sst of the screw shaft 123ss that penetrates the gear 123gr by sliding has a substantially rectangular prism shape. The through hole 123grh of the gear 123gr has a substantially square outer shape (see Figure 9).

[0037] The four outer planes 123ssp that make up the four sides of the roughly square outer shape of the screw shaft 123ss are provided with grooves 123ssg that extend along the central axis CA (see the middle section of Figure 8).

[0038] By adopting this configuration, any foreign matter that may be present between the outer surface 123ssp of the screw shaft 123ss and the inner surface 123grp of the through hole 123grh can be contained within the groove 123ssg as the screw shaft 123ss slides relative to the gear 123gr. As a result, damage to the outer surface 123ssp of the screw shaft 123ss, the inner surface 123grp of the through hole 123grh of the gear 123gr, and the roller 123cr caused by foreign matter can be reduced. The roller 123cr will be explained later.

[0039] Grease GR is placed in each groove 123ssg of the screw shaft 123ss (see the middle section of Figure 8).

[0040] Figure 10 is a perspective view showing the gear 123gr and the screw shaft 123ss. Figure 11 is a front view showing the gear 123gr and the screw shaft 123ss. However, in Figures 10 and 11, the gear 123gr is shown with a dashed line to facilitate technical understanding.

[0041] The transmission structure 123tr transmits the rotational force of the gear 123gr to the portion 123sst of the screw shaft 123ss that has a non-circular outer shape (see the lower right of Figure 10 and the middle center of Figure 11). The transmission structure 123tr is provided inside the through hole 123grh of the gear 123gr. More specifically, the transmission structure 123tr is positioned between the four outer planes 123ssp that constitute the four sides of the approximately square outer shape of the screw shaft 123ss and the four inner planes of the through hole 123grh that face these four outer planes 123ssp (see the lower right of Figure 10 and the middle center of Figure 11). Each transmission structure 123tr comprises a roller 123cr and a holder 123rt.

[0042] The roller 123cr is positioned between the four outer planes 123ssp that make up the four sides of the approximately square outer shape of the screw shaft 123ss, and the four inner planes of the through hole 123grh that face the four outer planes 123ssp (see the lower right part of Figure 10 and the middle center part of Figure 11). The roller 123cr has an approximately cylindrical shape. In the roller 123cr, both end faces of the cylinder protrude in a dome shape. The roller 123cr is positioned so that it can rotate about a direction that intersects the central axis CA perpendicularly when projected onto the central axis CA. The transmission structure 123tr has three rollers 123cr between each of the outer planes 123ssp that make up each side of the approximately square outer shape of the screw shaft 123ss, and each inner plane of the through hole 123grh that faces the four outer planes 123ssp.

[0043] Each holder 123rt is positioned between the four outer planes 123ssp that make up the four sides of the roughly square outer shape of the screw shaft 123ss, and the four inner planes of the through holes 123grh that face these four outer planes 123ssp (see the lower right part of Figure 10 and the middle center part of Figure 11). Each holder 123rt holds three rollers 123cr so that they can rotate around their respective central axes. Each holder 123rt has a plate-like structure that is bent to have a roughly M-shaped cross-section. Each holder 123rt has three roughly rectangular through holes. Each of the three rollers 123cr is positioned in a rotatable manner within the three through holes.

[0044] This configuration reduces wear on the outer surface 123ssp of the screw shaft 123ss and the inner surface 123grp of the through hole 123grh of the gear 123gr, compared to a configuration where the screw shaft and gear do not have rollers but have a spline shaft and spline boss. As a result, the positional accuracy of the screw shaft 123ss that moves the plunger 122 can be maintained at a high level. Furthermore, it offers higher durability compared to a configuration where the screw shaft and gear do not have rollers but have a spline shaft and spline boss.

[0045] Furthermore, this configuration reduces friction between the outer surface 123ssp of the screw shaft 123ss and the inner surface of the through hole 123gr of the gear 123gr. As a result, the rotational force that must be transmitted to the gear 123gr to move the screw shaft 123ss along the central axis CA can be reduced. Moreover, compared to configurations where the screw shaft and gear do not have rollers but have a spline shaft and spline boss, this configuration can withstand high loads in a smaller size.

[0046] In this embodiment, force is transmitted via a roller 123cr that makes line contact with the outer surface 123ssp of the screw shaft 123ss and the inner surface of the through hole 123grh of the gear 123gr. Therefore, it is possible to transmit a greater rotational force compared to an embodiment in which a ball spline, in which force is transmitted by point contact of spheres, is provided between the screw shaft and the gear.

[0047] Figure 12 is a cross-sectional view showing the screw shaft 123ss in its most forward position relative to the eccentric shaft 123es, the ring gear 123rg, and the gear 123gr. Figure 12 shows the plunger 122 in its most advanced position within the cylinder 121 (see the lower left of Figure 3). In other words, Figure 12 shows the plunger 122 pushing the plasticizing material into the flow path 116 as far as possible.

[0048] Figure 13 is a cross-sectional view showing the screw shaft 123ss in its most negative X-axis position relative to the eccentric shaft 123es, the ring gear 123rg, and the gear 123gr. Figure 13 shows the plunger 122 in its most retracted position within the cylinder 121 (see the lower left of Figure 3). In other words, Figure 13 shows the plunger 122 drawing as much of the plasticizing material as possible from the flow path 116.

[0049] The eccentric shaft 123es has a housing space 123hs (see the right side of Figure 12). The housing space 123hs can accommodate a portion of each groove 123ssg on the outer surface 123ssp of the screw shaft 123ss when the plunger 122 is in its most retracted position within the cylinder 121 (see the right side of Figure 13). Grease GR is placed on the inner wall defining this housing space 123hs.

[0050] With this configuration, the groove 123ssg of the screw shaft 123ss is housed in the eccentric shaft 123es, allowing the grease GR distributed on the inner wall of the eccentric shaft 123es to be additionally supplied to the groove 123ssg (see the right side of Figure 13). Therefore, compared to a configuration without an eccentric shaft 123es having grease GR on its inner wall, the lubrication between the outer surface 123ssp of the screw shaft 123ss and the inner surface 123grp of the through hole 123grh of the gear 123gr can be maintained for a longer period of time.

[0051] The screw shaft 123ss passes through the nut 123nt (see the middle left of Figure 6 and the lower center of Figure 7). The screw shaft 123ss is connected to the plunger 122. More specifically, the screw shaft 123ss is connected in series to the plunger 122 at one end (see the lower left of Figure 7, the left side of Figure 12, and the left side of Figure 13). The screw shaft 123ss has its central axis CA aligned with the central axis of the plunger 122 and the cylinder 121.

[0052] The nut 123nt is passed through by the screw shaft 123ss (see the middle left of Figure 6 and the lower left of Figure 7). The nut 123nt has several balls inside. The several balls roll along grooves provided on the outer surface of the screw shaft 123ss that pass through the nut 123nt, and circulate within the screw shaft 123ss. In other words, the nut 123nt and the screw shaft 123ss constitute a ball screw. The nut 123nt is fixed in the drive unit 123 (see the middle left of Figure 6 and the lower left of Figure 7). As a result, the nut 123nt is fixed in the injection unit 100.

[0053] The gear 123gr is connected to the screw shaft 123ss via a transmission structure 123tr in a through hole 123grh (see Figures 8 and 10). The gear 123gr has the central axis CA of the screw shaft 123ss as its central axis. The gear 123gr receives rotational force from an external source and rotates the screw shaft 123ss. More specifically, the gear 123gr receives rotational force from the ring gear 123rg. As the gear 123gr rotates, the screw shaft 123ss rotates together with the gear 123gr.

[0054] The screw shaft 123ss rotates about the central axis CA, moving relative to the nut 123nt along the direction of the central axis CA (see Figures 12 and 13). The plunger 122 is moved by the movement of the screw shaft 123ss relative to the nut 123nt, which is caused by the rotation of the screw shaft 123ss. As a result, plasticizing material is drawn into the cylinder 121 or pushed out from the cylinder 121 (see arrow RA in Figure 3).

[0055] In the injection unit 100 of this embodiment, when the plunger 122 is moved, the nut 123nt, which is inserted through the screw shaft 123ss, does not move within the injection unit 100 (see Figures 6, 7, 12, and 13). Therefore, there is no need to provide space within the injection unit 100 for the nut 123nt to move. Thus, it is easier to miniaturize the injection unit 100 compared to a configuration in which the ball screw nut moves within the injection unit 100.

[0056] In the injection unit 100 of this embodiment, the screw shaft 123ss passes through a through hole 123grh so as to be slidable along the direction of the central axis CA. A transmission structure 123tr provided inside the through hole 123grh of the gear 123gr transmits the rotational force of the gear 123gr to the portion 123sst of the screw shaft 123ss that has a non-circular outer shape (see Figures 10 to 13). Therefore, the gear 123gr can transmit rotational force to the screw shaft 123ss while sliding the screw shaft 123ss along the direction of the central axis CA without the gear 123gr moving along the direction of the central axis CA.

[0057] In the injection section 100 of this embodiment, the screw shaft 123ss has a substantially regular polygonal outer shape at the portion 123sst through the gear 123gr (see the middle section center of Figure 8 and the middle section center of Figure 10). Therefore, a force of substantially equal magnitude is applied to each side of the outer circumference of the screw shaft 123ss via the transmission structure 123tr, and rotational force can be transmitted from the gear 123gr to the screw shaft 123ss.

[0058] In the injection section 100 of this embodiment, grease GR is placed in the groove 123ssg (see the center of Figure 12). With this configuration, wear on the surface of the roller 123cr, the outer surface 123ssp of the screw shaft 123ss, and the inner surface 123grp of the through hole 123grh of the gear 123gr can be further reduced. As a result, the positional accuracy of the screw shaft 123ss that moves the plunger 122 can be maintained at an even higher level.

[0059] Furthermore, by distributing grease GR within the groove 123ssg, friction between the roller 123cr, the outer surface 123ssp of the screw shaft 123ss, and the inner surface 123grp of the through hole 123grh of the gear 123gr can be further reduced. As a result, the rotational force that must be transmitted to the gear 123gr to move the screw shaft 123ss can be further reduced.

[0060] In this embodiment, the injection unit 100 is also called the "material dispensing device." The flat screw 111, barrel 112, and heater 113 are also called the "plasticizing unit."

[0061] B. Other embodiments: B1. Other Embodiments 1: (1) In the above embodiment, the external shape of the portion 123sst of the screw shaft 123ss that penetrates the gear 123gr is approximately square (see Figures 8 and 10). However, the external shape of the portion 123sst of the screw shaft 123ss that penetrates the gear 123gr may be approximately hexagonal or approximately octagonal. Also, the external shape of the portion 123sst of the screw shaft 123ss that penetrates the gear 123gr may include an arc in part. However, it is preferable that the external shape of the portion 123sst of the screw shaft 123ss that penetrates the gear 123gr is approximately a regular polygon. Furthermore, it is even more preferable that the external shape of the portion 123sst that penetrates the gear 123gr is approximately square. A screw shaft 123ss having an approximately square external shape allows for easy positioning of the screw shaft, and the torsional rigidity of that portion of the screw shaft is also relatively high. Furthermore, the screw shaft 123ss, which has a roughly square external shape, is relatively easy to machine.

[0062] (2) In the above embodiment, the transmission structure 123tr is positioned between the four outer planes 123ssp that constitute the four sides of the substantially square outer shape of the screw shaft 123ss and the four inner planes of the through hole 123grh that face the four outer planes 123ssp (see the lower right part of Figure 10 and the middle center part of Figure 11). The transmission structure does not have to be provided on all opposing surfaces within the through hole 123grh of the gear 123gr. The transmission structure only needs to be provided inside the through hole 123grh. However, it is preferable that the transmission structure is provided between three or more outer planes that constitute three or more sides of the substantially regular polygonal outer shape of the screw shaft and three or more inner planes of the through hole that face the three or more outer planes. With such a configuration, the central axis of the screw shaft can be accurately positioned in three-dimensional space.

[0063] (3) In the above embodiment, the housing space 123hs can accommodate a portion of the groove 123ssg on the outer surface 123ssp of the screw shaft 123ss when the plunger 122 is in its most retracted position within the cylinder 121 (see the right side of Figure 13). However, the housing space can also be configured to accommodate the entire groove on the outer surface of the screw shaft when the plunger is in its most retracted position within the cylinder. When the plunger 122 is in its most advanced position within the cylinder 121, a portion of the groove 123ssg may be within the housing space 123hs, or the entire groove 123ssg may be outside the housing space 123hs.

[0064] B2. Another Embodiment 2: In the above embodiment, the drive unit 123 includes a transmission structure 123tr. The transmission structure 123tr is positioned between the four outer planes 123ssp that constitute the four sides of the approximately square outer shape of the screw shaft 123ss, and the four inner planes of the through hole 123grh that face the four outer planes 123ssp (see the lower right part of Figure 10 and the middle center part of Figure 11). However, the drive unit 123 can also be configured without such a transmission structure. For example, the portion 123sst of the screw shaft 123ss that penetrates the gear 123gr can be configured as a spline shaft, and the gear 123gr with the through hole 123grh can be configured as a spline boss.

[0065] B3. Other Embodiments 3: In the above embodiment, the external shape of the portion 123sst of the screw shaft 123ss that penetrates the gear 123gr is approximately a square as a roughly regular polygon (see Figures 8 and 10). However, the external shape of the portion 123sst of the screw shaft 123ss that penetrates the gear 123gr may be a shape other than a circle, such as a shape in which a part of a circle protrudes or a shape in which a part of a circle is cut out. On the other hand, it is preferable that the through hole 123gr of the gear 123gr has a plane that is opposite to the plane of the external shape of the portion 123sst of the screw shaft 123ss that penetrates the gear 123gr.

[0066] B4. Other Embodiments 4: In the above embodiment, each transmission structure 123tr comprises a roller 123cr and a holder 123rt (see the lower right part of Figure 10 and the middle center part of Figure 11). However, the transmission structure can also be configured to include a plurality of balls instead of rollers to transmit rotational force from an external source to the screw shaft.

[0067] B5. Other Embodiments 5: In the above embodiment, the four outer planes 123ssp that constitute the four sides of the substantially square outer shape of the screw shaft 123ss are provided with grooves 123ssg extending along the central axis CA (see the middle section of Figure 8). However, the grooves 123ssg may be provided on some of the planes that constitute the sides of the substantially regular polygonal outer shape of the screw shaft. Furthermore, the screw shaft may be configured in a way that does not have such grooves on its outer surface.

[0068] B6. Other Embodiments 6: In the above embodiment, grease GR is placed in each groove 123ssg of the screw shaft 123ss (see the middle section of Figure 8). However, grease does not have to be placed in each groove 123ssg of the screw shaft 123ss. In such an embodiment, any foreign matter that may be present between the outer surface 123ssp of the screw shaft 123ss and the inner surface 123grp of the through hole 123grh can be contained within the groove 123ssg as the screw shaft 123ss slides to form the gear 123gr.

[0069] B7. Other Embodiments 7: In the above embodiment, the eccentric shaft 123es has a housing space 123hs (see the right side of Figure 12). Grease GR is provided on the inner wall defining the housing space 123hs. However, grease GR does not have to be provided on the inner wall defining the housing space 123hs of the eccentric shaft 123es. In such an embodiment, for example, by providing grease GR in each groove 123ssg of the screw shaft 123ss, a lubricating state between the outer surface 123ssp of the screw shaft 123ss and the inner surface 123grp of the through hole 123grh of the gear 123gr can be maintained for a certain period of time.

[0070] C. Other forms: This disclosure is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit. For example, this disclosure can also be implemented in the following forms. The technical features in the embodiments described below that correspond to the technical features in each of the forms described below may be replaced or combined as appropriate in order to solve some or all of the problems of this disclosure, or to achieve some or all of the effects of this disclosure. Furthermore, if such technical features are not described as essential in this specification, they may be deleted as appropriate.

[0071] (1) According to one embodiment of the present disclosure, a material dispensing device for dispensing a plastic material is provided. The material dispensing device comprises a plasticizing unit that generates a plastic material by plasticizing a solid material; a nozzle having a nozzle opening for dispensing the plastic material from the nozzle opening; a suction extrusion unit communicating with the nozzle opening and through which the plastic material flows; a cylinder connected to the suction extrusion unit; a plunger; and a drive unit for moving the plunger relative to the cylinder, wherein the suction extrusion unit sucks the plastic material into the cylinder or pushes the plastic material out of the cylinder by the movement of the plunger. The drive unit comprises a screw shaft, a nut, and a gear, the nut being fixed in the material dispensing device, the screw shaft passing through the nut and connected to the plunger, the gear having the central axis of the screw shaft as its central axis, receiving rotational force from the outside to rotate the screw shaft, and the plunger being moved by the movement of the screw shaft relative to the nut, which is caused by the rotation of the screw shaft and is along the direction of the central axis. In this embodiment, when the plunger is moved, the nut that passes through the screw shaft does not move within the material dispensing device. Therefore, there is no need to provide space for the nut to move within the material dispensing device. Thus, it is easier to miniaturize the material dispensing device compared to an embodiment in which the nut moves within the material dispensing device.

[0072] (2) In the material dispensing device of the above form, the gear has a through hole aligned with the direction of the central axis, the screw shaft passes through the through hole so as to be slidable along the direction of the central axis, and at least a portion of the part that passes through the gear has a non-circular outer shape, and the material dispensing device may also be provided with a transmission structure inside the through hole that transmits the rotational force of the gear to the part of the screw shaft having the non-circular outer shape. In this configuration, the gear can transmit rotational force to the screw shaft while sliding the screw shaft along the direction of the central axis, without the gear moving along the direction of the central axis.

[0073] (3) In the material dispensing device of the above form, the screw shaft may also have an outer shape that is substantially a regular polygon in the portion that penetrates the gear. By adopting this configuration, a force of approximately equal magnitude is applied to each side of the outer circumference of the screw shaft via the transmission structure, thereby transmitting rotational force from the gear to the screw shaft.

[0074] (4) In the material dispensing device of the above form, there may also be a configuration in which one or more rollers are provided between three or more outer planes that constitute three or more sides of the substantially regular polygonal outer shape of the screw shaft and three or more inner planes of the through hole that face the three or more outer planes, and between each of these rollers is one or more rollers that can rotate about a direction that intersects the central axis perpendicularly when projected onto the central axis. By adopting this configuration, wear on the outer surface of the screw shaft and the inner surface of the through-hole of the gear can be reduced compared to a configuration in which the screw shaft and gear do not have rollers but do have a spline shaft and spline boss. As a result, the positional accuracy of the screw shaft that moves the plunger can be maintained at a high level. Furthermore, force is transmitted via rollers that make line contact between the outer surface of the screw shaft and the inner surface of the through-hole in the gear. Therefore, it can transmit greater rotational force compared to a ball spline, where force is transmitted by point contact of spherical objects.

[0075] (5) In the material dispensing device of the above form, at least one of the three or more outer surfaces may be provided with a groove extending along the central axis. By adopting this configuration, foreign matter that may be present between the outer surface of the screw shaft and the inner surface of the through hole can be contained within the groove as the screw shaft slides against the gear. As a result, damage to the outer surface of the screw shaft, the inner surface of the through hole of the gear, and the roller caused by foreign matter can be reduced.

[0076] (6) In the material dispensing device of the above form, grease may be provided in the groove. By adopting this configuration, wear on the roller surface, the outer surface of the screw shaft, and the inner surface of the gear through hole can be further reduced. As a result, the positional accuracy of the screw shaft that moves the plunger can be maintained at an even higher level. Furthermore, friction between the roller, the outer surface of the screw shaft, and the inner surface of the gear's through-hole can be further reduced. As a result, the rotational force that must be transmitted to the gear to move the screw shaft can be further reduced.

[0077] (7) In the material dispensing device of the above form, there may also be a screw housing portion having a housing space that can accommodate at least a portion of the groove on the outer surface of the screw shaft when the plunger is in its most retracted state within the cylinder, and grease is provided on the inner wall defining the housing space. In this configuration, the groove of the screw shaft is housed in the screw housing, allowing the grease distributed on the inner wall of the screw housing to be additionally supplied to the groove. Therefore, compared to a configuration without a screw housing with grease on its inner wall, the lubrication between the outer surface of the screw shaft and the inner surface of the gear's through-hole can be maintained for a longer period.

[0078] This disclosure can also be implemented in various forms other than centrifugal dehydrators. For example, it can be implemented in the form of a method for manufacturing or designing a material dispensing device, a computer program that implements the control method thereof, or a non-temporary recording medium that stores the computer program. [Explanation of Symbols]

[0079] 10…Injection molding machine, 30…Hopper, 100…Injection unit, 101…Storage unit, 110…Plasticizer, 111…Flat screw, 112…Barrel, 113…Heater, 114…Nozzle, 114o…Nozzle opening, 115…Communication hole, 116…Flow path, 118…Drive motor, 119…Drive shaft, 120…Suction extrusion unit, 121…Cylinder, 122…Plunger, 123…Drive unit, 123bt…Toothed belt, 123cr…Roller, 123es…Eccentric shaft, 123grh…Through hole, 123gr…Gear, 123grp…Inner surface, 123hs…Storage space, 123mt…Electric motor, 123nt… Nut, 123p1...toothed pulley, 123p2...toothed pulley, 123rg...ring gear, 123rt...retainer, 123ss...screw shaft, 123sst...part of the screw shaft that penetrates the gear, 123ssg...groove, 123ssp...outer surface, 123tr...transmission structure, 124...check valve, 130...clip clamping device, 131...mold drive unit, 132...ball screw, 160...molding mold, 161...fixed mold, 162...movable mold, 201...groove forming surface, 202...groove, 203...material input port, 204...protruding part, 205...center part, 211...guide groove, 212...opposing surface, 500...control unit, CA...central shaft, GR...grease, RX...central shaft.

Claims

1. A material dispensing device that dispenses a plastic material, A plasticizing unit that generates a plasticizable material by plasticizing a solid material, A suction extrusion unit comprising a cylinder connected to the plasticizing unit, a plunger, and a drive unit for moving the plunger relative to the cylinder, wherein the suction extrusion unit draws the plasticizing material into the cylinder or pushes the plasticizing material out of the cylinder by the movement of the plunger, The aforementioned drive unit comprises a screw shaft, a nut, and a gear. The nut is fixed in the material dispensing device. The screw shaft passes through the nut and is connected to the plunger. The gear has the central axis of the screw shaft as its central axis, receives rotational force from the outside, and rotates the screw shaft. A material dispensing device in which the plunger is moved by the movement of the screw shaft relative to the nut, which is caused by the rotation of the screw shaft, and is moved along the direction of the central axis.

2. A material dispensing device according to claim 1, The gear has a through hole aligned with the direction of the central axis, The screw shaft passes through the through hole so as to be slidable along the direction of the central axis, and at least a portion of the part that passes through the gear has a non-circular outer shape. The material dispensing device is a material dispensing device that includes a transmission structure inside the through hole for transmitting the rotational force of the gear to the portion of the screw shaft having the non-circular outer shape.

3. A material dispensing device according to claim 2, The material dispensing device wherein the screw shaft has a substantially regular polygonal outer shape in the portion that penetrates the gear.

4. A material dispensing device according to claim 3, A material dispensing device comprising, between three or more outer planes constituting three or more sides of the substantially regular polygonal outer shape of the screw shaft, and three or more inner planes of the through hole facing the three or more outer planes, one or more rollers that can rotate about a direction perpendicular to the central axis when projected onto the central axis.

5. A material dispensing device according to claim 4, A material dispensing device wherein at least one of the three or more outer surfaces is provided with a groove extending along the central axis.

6. A material dispensing device according to claim 5, A material dispensing device in which grease is placed in the groove.

7. A material dispensing device according to claim 6, A material dispensing device comprising a screw housing section having a housing space capable of accommodating at least a portion of the groove on the outer surface of the screw shaft when the plunger is in its most retracted state within the cylinder, and grease being disposed on the inner wall defining the housing space.

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