Injection molding apparatus

Abstract

To provide an injection molding apparatus capable of increasing the holding pressure during holding without increasing the capacity of a motor.SOLUTION: A power transmission part has a rotary plate provided with a rotary shaft at an eccentric position, and a support part formed with a hole through which the rotary shaft passes and which supports a plunger. The hole part extends in the moving direction of the plunger, the support part swings in the extending direction of the hole part due to the rotation of the rotary plate, and the angle formed by a straight line connecting the rotary shaft and the center of the rotary plate and the moving direction of the plunger is larger than 90° and less than 180° when viewed from the direction of the rotary shaft at the end of the delivery processing. A control part controls the number of rotations of the motor according to the angle in the delivery processing.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to an injection molding apparatus.

Background Art

[0002] There is known an injection molding apparatus that forms a molded product by injecting a material plasticized by a plasticizing unit toward a cavity and curing it.

[0003] For example, Patent Document 1 describes an injection molding machine including an injection control unit having a cylinder, a plunger that moves within the cylinder, and a plunger drive unit that drives the plunger.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the injection molding machine as described above, when holding the pressure on the plasticized material filled in the cavity after filling the cavity with the plasticized material, a load is applied to the motor of the plunger drive unit. Therefore, in some cases, it is necessary to increase the size of the motor.

Means for Solving the Problems

[0006] One aspect of the injection molding apparatus according to the present invention is a plasticizing unit that plasticizes a material to generate a plasticized material, a nozzle in which a nozzle opening is formed and that sends out the plasticized material from the nozzle opening, A suction and delivery unit having a cylinder communicating with the nozzle opening and connected to a flow path through which the plasticized material flows, a plunger reciprocating within the cylinder, a motor for driving the plunger, and a power transmission unit for transmitting the power of the motor to the plunger; a control unit for controlling the motor; comprising the control unit performs a suction process of sucking the plasticized material into the cylinder by controlling the rotational speed of the motor to move the plunger in a direction away from the flow path, and a delivery process of delivering the plasticized material in the cylinder to the nozzle by controlling the rotational speed of the motor to move the plunger in a direction approaching the flow path, and performs the power transmission unit has a rotating plate provided with a rotating shaft at an eccentric position, and a support portion having a hole through which the rotating shaft passes and supporting the plunger, and has the hole extends in the moving direction of the plunger, the support portion swings in the extending direction of the hole as the rotating plate rotates, at the end point of the delivery process, when viewed from the rotating shaft direction, the angle formed by the straight line connecting the rotating shaft and the center of the rotating plate and the moving direction of the plunger is greater than 90° and less than 180°, the control unit controls the rotational speed of the motor according to the angle in the delivery process.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Mode for Carrying Out the Invention

[0008] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Note that the embodiments described below do not unduly limit the content of the present invention described in the claims. Also, not all of the configurations described below are essential constituent elements of the present invention.

[0009] 1. Injection Molding Apparatus 1.1. Overall Configuration First, the injection molding apparatus according to the present embodiment will be described with reference to the drawings. FIG. 1 is a side view schematically showing the injection molding apparatus 100 according to the present embodiment. In FIG. 1, the X-axis, Y-axis, and Z-axis are shown as three axes orthogonal to each other. The X-axis direction and the Y-axis direction are, for example, horizontal directions. The Z-axis direction is, for example, the vertical direction.

[0010] As shown in Fig. 1, the injection molding apparatus 100 includes a material supply unit 10, an injection unit 20, a mold unit 30, a mold clamping unit 40, and a control device 50.

[0011] The material supply unit 10 supplies a material as a raw material to the injection unit 20. The material supply unit 10 is constituted by, for example, a hopper. The shape of the material supplied from the material supply unit 10 is, for example, pellet shape or powder shape. The material supplied by the material supply unit 10 is, for example, acrylonitrile butadiene styrene (ABS) resin.

[0012] The injection unit 20 plasticizes the material supplied from the material supply unit 10 to make it a plasticized material. Then, the injection unit 20 injects the plasticized material toward the mold unit 30.

[0013] Note that plasticization is a concept including melting, and it 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 means raising the temperature of the material above the glass transition point. In the case of a material in which glass transition does not occur, plasticization means raising the temperature of the material above the melting point.

[0014] A cavity corresponding to the shape of the molded product is formed in the mold unit 30. The plasticized material injected from the injection unit 20 flows into the cavity. Then, the plasticized material is cooled and solidified to produce a molded product.

[0015] The mold clamping unit 40 opens and closes the mold unit 30. After the plasticized material is cooled and solidified, the mold clamping unit 40 opens the mold unit 30. Thereby, the molded product is discharged to the outside.

[0016] The control device 50 is constituted by, for example, a computer having a processor, a main memory device, and an input / output interface for inputting and outputting signals to and from the outside. The control device 50 exhibits various functions by, for example, the processor executing a program read into the main memory device. Specifically, the control device 50 controls the injection unit 20 and the mold clamping unit 40. Note that the control device 50 may be constituted by a combination of a plurality of circuits instead of a computer.

[0017] 1.2. Specific Configuration FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1 schematically showing the injection molding apparatus 100. As shown in FIG. 2, the injection unit 20 has, for example, a plasticizing unit 60, a suction and delivery unit 70, and a nozzle 80.

[0018] The plasticizing unit 60 is configured to plasticize at least a part of the material supplied from the material supply unit 10, generate a paste-like plasticized material having fluidity, and guide it to the suction and delivery unit 70. The plasticizing unit 60 includes, for example, a screw case 62, a drive motor 64, a flat screw 110, a barrel 120, and a heater 130.

[0019] The screw case 62 is a housing that houses the flat screw 110. The flat screw 110 is housed in a space surrounded by the screw case 62 and the barrel 120.

[0020] The drive motor 64 is connected to the screw case 62. The drive motor 64 rotates the flat screw 110. The drive motor 64 is, for example, a servo motor. The shaft 66 of the drive motor 64 is connected to the flat screw 110. The drive motor 64 is controlled by the control unit 56 of the control device 50.

[0021] The flat screw 110 has a substantially cylindrical shape in which the size in the direction of the rotation axis R is smaller than the size in the direction orthogonal to the direction of the rotation axis R. In the illustrated example, the rotation axis R is parallel to the Y-axis. The flat screw 110 rotates about the rotation axis R by the torque generated by the drive motor 64. The flat screw 110 has, for example, a shaft surface 111 to which the shaft 66 is connected, a groove forming surface 112 on the side opposite to the shaft surface 111, and a connecting surface 113 connecting the shaft surface 111 and the groove forming surface 112. Here, FIG. 3 is a perspective view schematically showing the flat screw 110. For the sake of convenience, in FIG. 3, the state where the vertical positional relationship is opposite to the state shown in FIG. 2 is shown.

[0022] As shown in FIG. 3, a first groove 114 is formed in the groove forming surface 112 of the flat screw 110. The first groove 114 has, for example, a central portion 115, a connecting portion 116, and a material introduction portion 117. The central portion 115 faces the communication hole 126 formed in the barrel 120. The central portion 115 communicates with the communication hole 126. The connecting portion 116 connects the central portion 115 and the material introduction portion 117. In the illustrated example, the connecting portion 116 is formed in a spiral shape from the central portion 115 toward the outer periphery of the groove forming surface 112. The material introduction portion 117 is formed on the outer periphery of the groove forming surface 112. That is, the material introduction portion 117 is formed on the connecting surface 113 of the flat screw 110. The material supplied from the material supply unit 10 is introduced into the first groove 114 from the material introduction portion 117, passes through the connecting portion 116 and the central portion 115, and is conveyed to the communication hole 126 formed in the barrel 120. In the illustrated example, two first grooves 114 are formed.

[0023] Note that the number of the first grooves 114 is not particularly limited. Although not shown, three or more first grooves 114 may be formed, or only one first groove 114 may be formed.

[0024] Also, although not shown in the drawings, the plasticizing unit 60 may have a long in-line screw having spiral grooves on its side surface instead of the flat screw 110. And the plasticizing unit 60 may plasticize the material by rotating the in-line screw.

[0025] As shown in FIG. 2, the barrel 120 is provided opposite to the flat screw 110. The barrel 120 has an opposing surface 122 that faces the groove-forming surface 112 of the flat screw 110. The opposing surface 122 faces the groove-forming surface 112 in the Y-axis direction. A communication hole 126 is formed at the center of the opposing surface 122. Here, FIG. 4 is a diagram schematically showing the barrel 120.

[0026] As shown in FIG. 4, a second groove 124 and a communication hole 126 are formed in the opposing surface 122 of the barrel 120. A plurality of second grooves 124 are formed. In the illustrated example, six second grooves 124 are formed, but the number is not particularly limited. The plurality of second grooves 124 are formed around the communication hole 126 when viewed in the Y-axis direction. One end of the second groove 124 is connected to the communication hole 126 and extends spirally from the communication hole 126 toward the outer periphery of the opposing surface 122. The second groove 124 has a function of guiding the plasticized material to the communication hole 126. The communication hole 126 allows the plasticized material to flow out of the barrel 120.

[0027] Note that the shape of the second groove 124 is not particularly limited and may be, for example, linear. Also, one end of the second groove 124 may not be connected to the communication hole 126. Furthermore, the second groove 124 may not be formed in the opposing surface 122. However, considering efficiently guiding the plasticized material to the communication hole 126, it is preferable that the second groove 124 is formed in the opposing surface 122.

[0028] As shown in FIG. 2, the heater 130 is provided in the barrel 120. The heater 130 heats the material supplied between the flat screw 110 and the barrel 120. The heater 130 heats the material supplied to the first groove 114. The heater 130 is controlled by the control unit 56 of the control device 50. The plasticizing unit 60 heats and plasticizes the material while conveying it toward the communication hole 126 by the flat screw 110, the barrel 120, and the heater 130, and causes the generated plasticized material to flow out from the communication hole 126 to the suction and delivery unit 70.

[0029] The suction and delivery unit 70 has a cylinder 73 and a plunger 78. The suction and delivery unit 70 guides the plasticized material located in the communication hole 126 into the cylinder 73 by moving the plunger 78 in the -X axis direction away from the communication hole 126 and measures it in the cylinder 73. Then, the suction and delivery unit 70 injects the plasticized material in the cylinder 73 into the mold part 30 through the nozzle 80 by moving the plunger 78 in the +X axis direction approaching the communication hole 126. Details of the suction and delivery unit 70 will be described later. In FIG. 2, the suction and delivery unit 70 is shown in a simplified manner.

[0030] The nozzle 80 is formed with a nozzle hole 82. The nozzle hole 82 communicates with the communication hole 126. The nozzle hole 82 has a nozzle opening 84 through which the plasticized material is injected. The nozzle 80 sends the plasticized material supplied from the plasticizing unit 60 toward the mold 32 of the mold part 30 from the nozzle opening 84. Specifically, the plasticized material measured in the cylinder 73 is sent from the suction and delivery unit 70 to the nozzle hole 82 through the communication hole 126. Then, the plasticized material is injected from the nozzle opening 84 of the nozzle hole 82 into the mold part 30.

[0031] The nozzle hole 82 and the communication hole 126 constitute a flow path 140 through which the plasticized material flows. In the illustrated example, the longitudinal direction of the flow path 140 is the Y axis direction. The cylinder 73 is connected to the flow path 140. In the illustrated example, the cylinder 73 extends in the X axis direction.

[0032] As shown in FIG. 2, the nozzle 80 has an opening / closing mechanism 86 for opening and closing the nozzle opening 84. The opening / closing mechanism 86 is configured such that the nozzle opening 84 opens when the pressure in the flow path 140 is greater than a predetermined pressure (hereinafter also referred to as the "nozzle release pressure"). The opening / closing mechanism 86 is constituted by, for example, a valve or the like.

[0033] The mold part 30 has a molding die 32. The molding die 32 is a mold. The plasticized material sent to the nozzle hole 82 is injected from the nozzle hole 82 into the cavity 34 of the molding die 32. Specifically, the molding die 32 has a movable die 36 and a fixed die 38 that face each other, and has a cavity 34 between the movable die 36 and the fixed die 38. The cavity 34 is a space corresponding to the shape of the molded product. The materials of the movable die 36 and the fixed die 38 are metals. Note that the materials of the movable die 36 and the fixed die 38 may be ceramics or resins.

[0034] The mold clamping part 40 has, for example, a mold driving part 42 and a ball screw part 44. The mold driving part 42 is constituted by, for example, a motor, gears, etc. The mold driving part 42 is connected to the movable die 36 via the ball screw part 44. The mold driving part 42 is controlled by the control part 56 of the control device 50. The ball screw part 44 transmits the power generated by the driving of the mold driving part 42 to the movable die 36. The mold clamping part 40 opens and closes the mold part 30 by moving the movable die 36 by the mold driving part 42 and the ball screw part 44.

[0035] The control device 50 has, for example, a storage part 52, a display part 54, and a control part 56.

[0036] The storage part 52 stores programs, data, etc. for the control part 56 to perform various calculation processes and control processes. Further, the storage part 52 is used as a work area for the control part 56. The storage part 52 is constituted by, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), etc.

[0037] The display unit 54 displays various images according to instructions from the control unit 56. The display unit 54 is composed of, for example, an LCD (Liquid Crystal Display), an organic EL (Electroluminescence) display, an EPD (Electrophoretic Display), a touch panel type display, and the like.

[0038] The control unit 56 performs various calculation processes and control processes according to, for example, a program stored in the storage unit 52. The control unit 56 is composed of, for example, a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), and the like.

[0039] 1.3. Suction and Delivery Unit FIG. 5 and FIG. 6 are perspective views schematically showing the suction and delivery unit 70 of the injection molding apparatus 100 according to the present embodiment. FIG. 7 is a sectional view taken along line VII-VII of FIG. 5 schematically showing the suction and delivery unit 70 of the injection molding apparatus 100 according to the present embodiment.

[0040] As shown in FIGS. 5 to 7, the suction and delivery unit 70 has, for example, a housing 72, a plunger 78, a motor 79, and a power transmission unit 150. For convenience, in FIG. 5, the internal structure of the housing 72 is shown by a broken line. Also, in FIG. 6, the illustration of the housing 72 is omitted.

[0041] As shown in FIG. 5, the shape of the housing 72 has, for example, a substantially rectangular parallelepiped shape. The housing 72 houses the plunger 78 and the power transmission unit 150. The housing 72 constitutes a cylinder 73. The cylinder 73 communicates with the nozzle opening 84 and is connected to a flow path 140 through which the plasticized material flows. The cylinder 73 extends, for example, in the -X axis direction from the flow path 140.

[0042] The plunger 78 reciprocates within the cylinder 73. In the illustrated example, the plunger 78 reciprocates in the X-axis direction within the cylinder 73. The +X-axis direction is the direction in which the plunger 78 approaches the flow path 140. The -X-axis direction is the direction in which the plunger 78 moves away from the flow path 140. The plunger 78 is a rod-shaped member extending in the X-axis direction. The plunger 78 is composed of, for example, one member.

[0043] The motor 79 drives the plunger 78 via the power transmission unit 150. The type of the motor 79 is not particularly limited as long as it can drive the plunger 78. The motor 79 is controlled by the control unit 56.

[0044] The power transmission unit 150 transmits the force of the motor 79 to the plunger 78. As shown in FIGS. 6 and 7, the power transmission unit 150 has, for example, a rotating plate 152, a shaft 154, a support portion 156, and a biasing portion 158.

[0045] As shown in FIG. 5, the rotating plate 152 is provided in the first opening 74 formed in the housing 72. The shape of the rotating plate 152 is, for example, a disc shape. The rotating plate 152 rotates about the rotation axis Q. In the illustrated example, the rotation axis Q is parallel to the Z-axis. As shown in FIG. 7, the rotation axis Q is provided at an eccentric position of the rotating plate 152. That is, when viewed from the Z-axis direction, the rotation axis Q is separated from the center O of the rotating plate 152.

[0046] The shaft 154 connects the rotating plate 152 and the motor 79. In the illustrated example, the shaft 154 is a rod-shaped member extending in the Z-axis direction. The shaft 154 rotates about the rotation axis Q by the drive of the motor 79. As the shaft 154 rotates, the rotating plate 152 rotates. The rotation axis Q is the central axis of the shaft 154.

[0047] The support portion 156 supports the plunger 78. As shown in FIGS. 6 and 7, the support portion 156 has a first wall portion 156a, a second wall portion 156b, a third wall portion 156c, and a fourth wall portion 156d.

[0048] The first wall portion 156a of the support portion 156 is provided between the rotating plate 152 and the plunger 78. The plunger 78 is connected to the first wall portion 156a. As shown in FIGS. 5 and 7, a second opening 75 into which the first wall portion 156a is inserted is formed in the housing 72. The second opening 75 is located between the cylinder 73 and the first opening 74. The size of the second opening 75 in the direction orthogonal to the X-axis direction is larger than the size of the cylinder 73 in the direction orthogonal to the X-axis direction. Thereby, the housing 72 has a stepped surface 76.

[0049] The second wall portion 156b of the support portion 156 is disposed opposite to the first wall portion 156a as shown in FIGS. 6 and 7. The rotating plate 152 is provided between the first wall portion 156a and the second wall portion 156b in the X-axis direction. In the example shown in FIG. 7, the second wall portion 156b is in contact with the side surface 153 of the rotating plate 152.

[0050] The third wall portion 156c and the fourth wall portion 156d of the support portion 156 connect the first wall portion 156a and the second wall portion 156b. The rotating plate 152 is provided between the third wall portion 156c and the fourth wall portion 156d in the Y-axis direction. As shown in FIG. 6, a hole portion 157 is formed in the third wall portion 156c. The hole portion 157 penetrates the third wall portion 156c in the Z-axis direction. The rotating shaft Q and the shaft 154 pass through the hole portion 157. The hole portion 157 extends in the X-axis direction. When the rotating plate 152 rotates, the support portion 156 swings in the X-axis direction, which is the extending direction of the hole portion 157. As the support portion 156 swings, the plunger 78 moves in the X-axis direction.

[0051] As shown in FIG. 7, the biasing portion 158 is provided between the rotating plate 152 and the first wall portion 156a. The biasing portion 158 has a contact portion 158a and a spring 158b. The contact portion 158a is in contact with the side surface 153 of the rotating plate 152. The shape of the contact portion 158a is, for example, plate-shaped. The contact portion 158a is separated from the first wall portion 156a. The spring 158b connects the contact portion 158a and the first wall portion 156a. Note that the position of the biasing portion 158 is not limited to being between the rotating plate 152 and the first wall portion 156a.

[0052] When the rotating plate 152 rotates, the contact portion 158a of the biasing portion 158 moves in the +X-axis direction. As a result, the spring 158b contracts, and the biasing portion 158 biases the first wall portion 156a in the +X-axis direction. The biasing force by the biasing portion 158 is smaller than the reaction force of the plunger 78 due to the nozzle opening pressure. That is, when the pressure in the flow path 140 reaches the nozzle opening pressure, the biasing portion 158 cannot move the first wall portion 156a in the +X-axis direction. The "biasing force by the biasing portion 158" is the force with which the biasing portion 158 pushes the first wall portion 156a in the +X-axis direction. The "reaction force of the plunger 78" is the force with which the plunger 78 pushes the first wall portion 156a in the -X-axis direction due to the pressure in the flow path 140.

[0053] 1.4. Operation FIG. 8 is a flowchart for explaining the operation of the injection molding apparatus 100. Specifically, FIG. 8 is a flowchart for explaining the processing of the control unit 56.

[0054] The user operates an operation unit (not shown) to output a processing start signal for starting processing to the control unit 56. The processing start signal includes, for example, information regarding the type of material stored in the material supply unit 10 and information regarding the size in the X-axis direction (hereinafter, also simply referred to as "length") of the plunger 78. The operation unit is constituted by, for example, a mouse, a keyboard, a touch panel, or the like. When the control unit 56 receives the processing start signal, it starts the processing.

[0055] First, as shown in FIG. 8, the control unit 56 performs a process of obtaining the length of the plunger 78 as step S1. Specifically, the control unit 56 obtains the length of the plunger 78 from the process start signal. The length of the plunger 78 is set by the user.

[0056] Next, as step S2, the control unit 56 performs a process of selecting control data for controlling the rotation speed of the motor 79 from among those stored in the storage unit 52 according to the detected length of the plunger 78. The control data includes information regarding the time series of the rotation speed of the motor 79. Control data is stored in the storage unit 52 for each length of the plunger 78.

[0057] Note that the control unit 56 may create control data according to the detected length of the plunger 78 instead of reading the control data from the storage unit 52. For example, the control data may be created according to the length of the plunger 78 based on information regarding the time series of the rotation speed of the motor 79 stored in the storage unit 52 in advance.

[0058] Next, as step S3, the control unit 56 performs a process of generating a plasticized material. Specifically, the control unit 56 controls the drive motor 64 to supply a material between the flat screw 110 and the barrel 120, and controls the heater 130 to plasticize the material to generate a plasticized material.

[0059] Next, as step S4, the control unit 56 performs a suction process of sucking the plasticized material into the cylinder 73 by controlling the rotation speed of the motor 79 based on the control data and moving the plunger 78 in the -X axis direction. As a result, a predetermined amount of the plasticized material is sucked into the cylinder 73.

[0060] While detecting the pressure in the flow path 140, the control unit 56 performs the suction process in step S5. The control unit 56 detects the pressure in the flow path 140 while detecting, for example, the torque value of the motor 79. Although not shown in the figure, the control unit 56 may detect the pressure in the flow path 140 based on a pressure sensor (not shown) provided in the flow path 140. At the end of the suction process, the control unit 56 performs the suction process so that the biasing force of the biasing unit 158 is greater than the reaction force of the plunger 78.

[0061] Next, as step S5, the control unit 56 controls the rotational speed of the motor 79 based on the control data, and moves the plunger 78 in the +X-axis direction to perform a delivery process of delivering the plasticized material in the cylinder 73 to the nozzle 80. Here, FIG. 9 is a cross-sectional view for explaining the delivery process. The delivery process is divided into, for example, section A, section B, section C, and section D as shown in FIG. 9. In section A to section D, the rotary plate 152 is rotated in the S direction.

[0062] In section A, the biasing force of the biasing unit 158 is greater than the reaction force of the plunger 78. Therefore, the spring 158b of the biasing unit 158 is not compressed, and the plunger 78 moves in the +X-axis direction. Due to the movement of the plunger 78, the pressure in the flow path 140 increases, but does not reach the nozzle opening pressure.

[0063] In section B, the biasing force of the biasing unit 158 becomes equal to the reaction force of the plunger 78, and the movement of the plunger 78 in the +X-axis direction stops. The spring 158b of the biasing unit 158 begins to be compressed.

[0064] In section C, with the spring 158b fully compressed, the plunger 78 moves in the +X-axis direction again. Due to the movement of the plunger 78, the pressure in the flow path 140 increases, but does not reach the nozzle opening pressure.

[0065] In the D section, further, the plunger 78 moves in the +X-axis direction, and the pressure in the flow path 140 reaches the nozzle opening pressure. As a result, the plasticized material sucked into the cylinder 73 and metered in the suction process is injected from the nozzle opening 84 toward the mold 32. Then, the control unit 56 ends the delivery process.

[0066] Here, FIG. 10 is a diagram for explaining the delivery process, specifically, a view seen from the Z-axis direction. For convenience, in FIG. 10, the illustration of members other than the rotating plate 152 and the shaft 154 is omitted. FIG. 10 shows the states of the C section and the D section.

[0067] As shown in FIG. 10, in the delivery process, the angle θ changes. The angle θ is the angle formed by the first straight line L1 and the second straight line L2 as seen from the Z-axis direction. The first straight line L1 is a straight line connecting the rotation axis Q and the center O of the rotating plate 152. The second straight line L2 is parallel to the X-axis and passes through the rotation axis Q. The extending direction of the second straight line L2 is the moving direction of the plunger 78. The angle θ is the smallest in the A section and increases in the order of the B section, the C section, and the D section in the A section, the B section, the C section, and the D section. For example, in the A section, the angle θ is greater than 0° and less than 90°.

[0068] In the delivery process, the control unit 56 controls the rotation speed of the motor 79 according to the angle θ. For example, the control unit 56 controls the rotation speed of the motor 79 according to the angle θ so that the moving speed of the plunger 78 in the +X-axis direction in the C section is constant.

[0069] At the end point of the delivery process, that is, at the end point of the D section, the angle θ is greater than 90° and less than 180°, preferably 100° or more and 170° or less, more preferably 110° or more and 160° or less, and even more preferably 120° or more and 150° or less. The control unit 56 controls the motor 79 so that the angle θ is greater than 90° and less than 180° at the end point of the delivery process.

[0070] Next, as step S6, the control unit 56 performs a process of causing the display unit 54 to display the variable amount of the length of the plunger 78 based on the time-series data of the torque value of the motor 79 in the feeding process.

[0071] Specifically, the control unit 56 causes the storage unit 52 to store the time-series data of the torque value of the motor 79 in the feeding process. Then, after the feeding process is completed, the control unit 56 reads out the time-series data from the storage unit 52 and compares the time-series data with the control data for each length of the plunger 78 previously stored in the storage unit 52. From this comparison, the control unit 56 determines the variable amount of the length of the plunger 78 and causes the display unit 54 to display the variable amount. The "variable amount of the length of the plunger 78" refers to the length of the plunger 78 that enables the feeding process to be performed while keeping the load on the motor 79 below a predetermined value.

[0072] Furthermore, the control unit 56 calculates at least one of the maximum injection output, maximum holding pressure, longest holding time, and moving speed of the plunger 78 according to the length of the plunger 78 based on the time-series data of the torque value of the motor 79 in the feeding process, and performs a process of causing the calculated value to be displayed on the display unit 54.

[0073] Note that the "maximum injection output" is the maximum of the injection outputs applied in the direction of opening the mold 32 when the plasticized material is injected into the mold 32. The "maximum holding pressure" is the maximum of the holding pressures applied to the plasticized material injected into the mold 32. The "longest holding time" is the maximum of the holding times. The "moving speed of the plunger 78" is the moving speed of the plunger 78 in the X-axis direction. The display unit 54 may display the maximum of the moving speeds of the plunger 78.

[0074] Next, as step S7, the control unit 56 performs a process of applying pressure to the plasticized material injected into the mold 32 and holding the pressure. For example, the control unit 56 applies a pressure equal to or higher than the pressure in the flow path 140 at the end of the delivery process to the plasticized material injected into the mold 32. The closer the angle θ is to 180°, the more the load torque and output of the motor 79 can be suppressed. Furthermore, by suppressing the load torque and output to the motor 79, the holding pressure time can also be extended. In the holding pressure process, the moving speed of the plunger 78 in the +X-axis direction is smaller than that in the delivery process. In the holding pressure process, the movement of the plunger 78 in the +X-axis direction may be stopped. After a predetermined time has elapsed, the control unit 56 ends the holding pressure process.

[0075] Then, the control unit 56 ends the process. Note that the order of step S6 and step S7 is not particularly limited.

[0076] 1.5. Operational Effects In the injection molding apparatus 100, the power transmission unit 150 includes a rotating plate 152 having a rotating shaft Q provided at an eccentric position, and a support portion 156 that forms a hole portion 157 through which the rotating shaft Q passes and supports the plunger 78. The hole portion 157 extends in the moving direction of the plunger 78. When the rotating plate 152 rotates, the support portion 156 swings in the extending direction of the hole portion 157. At the end of the delivery process, when viewed from the direction of the rotating shaft Q, the angle θ formed by the first straight line L1 connecting the rotating shaft Q and the center O of the rotating plate 152 and the moving direction of the plunger 78 is greater than 90° and less than 180°. The control unit 56 controls the rotation speed of the motor 79 according to the angle θ in the delivery process.

[0077] Therefore, in the injection molding apparatus 100, the pressing force of the plunger 78 in the +X-axis direction can be increased as compared with the case where the angle θ is 90° or less. Therefore, the holding pressure during holding can be increased without increasing the capacity of the motor 79.

[0078] In the injection molding apparatus 100, the control unit 56 performs a process of creating control data for controlling the rotational speed of the motor 79 according to the detected length of the plunger 78, or a process of selecting from the control data stored in the storage unit 52. Therefore, in the injection molding apparatus 100, the suction process and the delivery process can be performed based on the control data corresponding to the length of the plunger 78.

[0079] In the injection molding apparatus 100, the control unit 56 performs a process of causing the display unit 54 to display the variable amount of the length of the plunger 78 based on the time-series data of the torque value of the motor 79 in the delivery process. Therefore, the user of the injection molding apparatus 100 can know the variable amount of the length of the plunger 78.

[0080] In the injection molding apparatus 100, the control unit 56 performs a process of causing the display unit 54 to display at least one of the maximum injection output, the maximum holding pressure, the longest holding time, and the moving speed of the plunger according to the length of the plunger 78. Therefore, the user of the injection molding apparatus 100 can know at least one of the maximum injection output, the maximum holding pressure, the longest holding time, and the moving speed of the plunger according to the length of the plunger 78.

[0081] In the injection molding apparatus 100, the support portion 156 is provided between the rotating plate 152 and the plunger 78 and has a first wall portion 156a to which the plunger 78 is connected. The power transmission portion 150 is provided between the first wall portion 156a and the rotating plate 152 and has a biasing portion 158 that biases the first wall portion 156a in a direction approaching the flow path 140. The nozzle 80 has an opening / closing mechanism 86 for opening and closing the nozzle opening 84. The opening / closing mechanism 86 is configured such that the nozzle opening 84 opens when the pressure in the flow path 140 is greater than the nozzle opening pressure. The biasing force by the biasing portion 158 is smaller than the reaction force of the plunger 78 by the nozzle opening pressure. Therefore, in the injection molding apparatus 100, the acceleration of the motor 79 can be completed before the plasticized material is ejected from the nozzle 80, and for example, the plunger 78 can be moved at a constant speed. Thereby, the leveling of the injection rate of the plasticized material can be achieved.

[0082] In the injection molding apparatus 100, the control unit 56 performs a suction process while detecting the pressure in the flow path 140. At the end of the suction process, the biasing force of the biasing unit 158 is greater than the reaction force of the plunger 78 due to the pressure in the flow path 140. Therefore, in the injection molding apparatus 100, the feeding process can be started in a state where the plunger 78 can be moved in the +X-axis direction by the biasing force of the biasing unit 158.

[0083] 2. Modification Example of Injection Molding Apparatus 2.1. First Modification Example Next, an injection molding apparatus according to the first modification example of the present embodiment will be described with reference to the drawings. FIG. 11 is a perspective view schematically showing the plunger 78 of the injection molding apparatus 200 according to the first modification example of the present embodiment.

[0084] Hereinafter, in the injection molding apparatus 200 according to the first modification example of the present embodiment, members having the same functions as the constituent members of the injection molding apparatus 100 according to the above-described present embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0085] In the above-described injection molding apparatus 100, the plunger 78 was composed of one part.

[0086] On the other hand, in the injection molding apparatus 200, the plunger 78 is composed of a plurality of parts. In the illustrated example, the plunger 78 is composed of two parts, a first part 178 and a second part 278.

[0087] The first part 178 constitutes the root portion of the plunger 78. The first part 178 is connected to, for example, the first wall portion 156a of the support portion 156. The first part 178 has a protrusion 179 that is inserted into the second part. For example, a male screw is provided on the surface of the protrusion 179.

[0088] The second component 278 constitutes the tip portion of the plunger 78. The second component 278 is connected to the first component 178. The first component 178 and the second component 278 are arranged side by side in the X-axis direction, which is the moving direction of the plunger 78. The second component 278 has an insertion hole 279 into which the protrusion 179 of the first component 178 is inserted. On the inner surface of the insertion hole 279, for example, a female screw that engages with the male screw of the protrusion 179 is provided.

[0089] The first component 178 and the second component 278 are detachably connected to each other. For example, by screwing and unscrewing the male screw of the protrusion 179 and the female screw of the insertion hole 279, the first component 178 and the second component 278 can be detachably connected.

[0090] In the above description, an example in which the plunger 78 is composed of two components has been described. However, the number of components constituting the plunger 78 is not particularly limited. Although not shown in the drawings, the plunger 78 may be composed of three or more components.

[0091] In the injection molding apparatus 200, the plunger 78 is composed of a plurality of components. The plurality of components are detachable and arranged side by side in the moving direction of the plunger 78. Therefore, in the injection molding apparatus 200, the length of the plunger 78 can be easily changed.

[0092] 2.2. Second Modified Example Next, an injection molding apparatus according to a first modified example of the present embodiment will be described with reference to the drawings. FIG. 12 is a perspective view schematically showing the plunger 78 of the injection molding apparatus 300 according to the first modified example of the present embodiment.

[0093] Hereinafter, in the injection molding apparatus 300 according to the second modified example of the present embodiment, members having the same functions as the constituent members of the injection molding apparatus 100 according to the present embodiment described above are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0094] In the injection molding apparatus 300, similar to the injection molding apparatus 200 described above, the plunger 78 has a first component 178 and a second component 278. The second component 278 has a convex portion 302 formed on its periphery. In the illustrated example, the convex portion 302 encircles the second component 278. The convex portion 302 may be integrally formed with the second component 278.

[0095] When the control unit 56 acquires the length of the plunger 78, it controls the motor 79 to bring the convex portion 302 into contact with the step surface 76 as a reference corresponding to the moving direction of the plunger 78. Then, the control unit 56 detects the length of the plunger 78 by detecting the torque value of the motor 79. When the plunger 78 contacts the step surface 76, the torque value of the motor 79 increases. Therefore, by varying the position where the convex portion 302 is provided according to the length of the second component 278, the length of the plunger can be detected from the torque value.

[0096] In the injection molding apparatus 300, the plunger 78 has a convex portion 302 formed on its periphery, and the control unit 56 performs a process of detecting the length of the plunger 78 by bringing the convex portion 302 formed on the plunger 78 into contact with a reference corresponding to the moving direction of the plunger 78 and detecting the torque value of the motor 79. Therefore, in the injection molding apparatus 300, the length of the plunger 78 can be easily detected.

[0097] Although not shown in the figure, the reference with which the convex portion 302 contacts may be provided in the -X axis direction of the plunger 78.

[0098] Also, although not shown in the figure, a concave portion may be formed in the second component 278, and the support portion 156 may be formed with a convex portion as a reference that engages with the concave portion. Then, the length of the plunger 78 may be detected by bringing the surface of the second component 278 that defines the concave portion into contact with the convex portion.

[0099] 2.3. Third Modification Example Next, an injection molding apparatus according to a third modification of the present embodiment will be described. Hereinafter, in the injection molding apparatus according to the second modification of the present embodiment, differences from the example of the injection molding apparatus 100 according to the present embodiment described above will be described, and descriptions of the same points will be omitted.

[0100] In the injection molding apparatus 100 described above, the material supplied from the material supply unit 10 was an ABS resin.

[0101] On the other hand, in the injection molding apparatus according to the second modification of the present embodiment, the material supplied from the material supply unit 10 is a material other than the ABS resin, or a material in which other components are added to the ABS resin. Since the injection molding apparatus according to the present invention can increase the holding pressure during holding pressure, the types of resins that can be handled can be increased.

[0102] Examples of the material supplied from the material supply unit 10 include materials mainly made of various materials such as thermoplastic materials, metal materials, and ceramic materials. Here, the "main material" means the central material that forms the shape of the molded product molded by the injection molding apparatus, and means a material that occupies a content rate of 50% by mass or more in the molded product. The materials described above include those in which the main materials are melted alone and those in which some components contained together with the main materials are melted into a paste shape.

[0103] As the thermoplastic material, for example, a thermoplastic resin can be used. Examples of the thermoplastic resin include general-purpose engineering plastics and super engineering plastics.

[0104] Examples of general-purpose engineering plastics include polypropylene (PP), polyethylene (PE), polyacetal (POM), polyvinyl chloride (PVC), polyamide (PA), polylactic acid (PLA), polyphenylene sulfide (PPS), polycarbonate (PC), modified polyphenylene ether, polybutylene terephthalate, and polyethylene terephthalate.

[0105] Examples of super engineering plastics include polysulfone (PSU), polyethersulfone (PES), polyphenylene sulfide (PPS), polyarylate (PAR), polyimide (PI), polyamideimide (PAI), polyetherimide (PEI), and polyetheretherketone (PEEK).

[0106] The thermoplastic material may be mixed with pigments, metals, ceramics, and other additives such as waxes, flame retardants, antioxidants, and heat stabilizers. In the plasticizing section 60, the thermoplastic material is plasticized and converted into a molten state by the rotation of the flat screw 110 and the heating of the heater 130. Further, the plasticized material thus produced hardens due to a decrease in temperature after being deposited from the nozzle 80. It is desirable that the thermoplastic material be heated above its glass transition point and discharged from the nozzle 80 in a completely molten state.

[0107] In the plasticizing section 60, for example, a metal material may be used as the main material instead of the above-described thermoplastic material. In this case, it is desirable that a component that melts during the production of the plasticized material be mixed with the powdered metal material and then introduced into the plasticizing section 60.

[0108] Examples of metal materials include single metals such as magnesium (Mg), iron (Fe), cobalt (Co), chromium (Cr), aluminum (Al), titanium (Ti), copper (Cu), nickel (Ni), or alloys containing one or more of these metals. Also, maraging steel, stainless steel, cobalt chromium molybdenum, titanium alloy, nickel alloy, aluminum alloy, cobalt alloy, and cobalt chromium alloy can be mentioned.

[0109] In the plasticizing section 60, it is possible to use a ceramic material as the main material instead of the above-mentioned metal material. Examples of the ceramic material include oxide ceramics such as silicon dioxide, titanium dioxide, aluminum oxide, and zirconium oxide, and non-oxide ceramics such as aluminum nitride.

[0110] The powder materials of the metal material or ceramic material supplied from the material supply section 10 may be a mixed material obtained by mixing a plurality of powders of a single metal, an alloy powder, or a ceramic material powder. Further, the powder materials of the metal material or ceramic material may be coated with, for example, the above-mentioned thermoplastic resin or other thermoplastic resin. In this case, in the plasticizing section 60, it may be assumed that the thermoplastic resin melts and exhibits fluidity.

[0111] For example, a solvent can also be added to the powder materials of the metal material or ceramic material supplied from the material supply section 10. Examples of the solvent include water; (poly)alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether; acetate esters such as ethyl acetate, n-propyl acetate, iso-propyl acetate, n-butyl acetate, and iso-butyl acetate; aromatic hydrocarbons such as benzene, toluene, and xylene; ketones such as methyl ethyl ketone, acetone, methyl isobutyl ketone, ethyl-n-butyl ketone, diisopropyl ketone, and acetylacetone; alcohols such as ethanol, propanol, and butanol; tetraalkylammonium acetates; sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide; pyridine solvents such as pyridine, γ-picoline, and 2,6-lutidine; tetraalkylammonium acetate (for example, tetrabutylammonium acetate, etc.); ionic liquids such as butyl carbitol acetate.

[0112] In addition, a binder may be added to the powder materials of metallic materials and ceramic materials supplied from the material supply unit 10, for example. Examples of the binder include acrylic resins, epoxy resins, silicone resins, cellulose-based resins, or other synthetic resins, or PLA, PA, PPS, PEEK, or other thermoplastic resins.

[0113] The above-described embodiments and modifications are merely examples and are not intended to be limiting. For example, it is also possible to appropriately combine each embodiment and each modification.

[0114] The present invention includes configurations that are substantially the same as the configurations described in the embodiments, for example, configurations having the same functions, methods, and results, or configurations having the same objectives and effects. The present invention also includes configurations in which non-essential portions of the configurations described in the embodiments are replaced. The present invention also includes configurations that exhibit the same operational effects as the configurations described in the embodiments or configurations that can achieve the same objectives. The present invention also includes configurations in which known technologies are added to the configurations described in the embodiments.

[0115] The following content is derived from the above-described embodiments and modifications.

[0116] One aspect of the injection molding apparatus is a plasticizing unit that plasticizes a material to generate a plasticized material, a nozzle in which a nozzle opening is formed and that sends out the plasticized material from the nozzle opening, a cylinder that communicates with the nozzle opening and is connected to a flow path through which the plasticized material flows, a plunger that reciprocates within the cylinder, a motor that drives the plunger, and a power transmission unit that transmits the power of the motor to the plunger, and a suction and delivery unit having the same, a control unit that controls the motor, and includes wherein the control unit controls the rotational speed of the motor to move the plunger in a direction away from the flow path, thereby performing a suction process of sucking the plasticized material into the cylinder, By controlling the rotational speed of the motor to move the plunger in a direction approaching the flow path, a delivery process for delivering the plasticized material in the cylinder to the nozzle is performed, and the power transmission unit includes a rotating plate having a rotating shaft provided at an eccentric position, and a support portion that forms a hole through which the rotating shaft passes and supports the plunger, and the hole extends in the moving direction of the plunger, and the support portion swings in the extending direction of the hole as the rotating plate rotates, at the end point of the delivery process, when viewed from the direction of the rotating shaft, the angle formed by the straight line connecting the rotating shaft and the center of the rotating plate and the moving direction of the plunger is greater than 90° and less than 180°, and the control unit controls the rotational speed of the motor according to the angle in the delivery process.

[0117] According to this injection molding apparatus, the holding pressure during holding pressure can be increased without increasing the capacity of the motor.

[0118] In one aspect of the injection molding apparatus, the plunger is composed of a plurality of parts, the plurality of parts are detachable and may be arranged in the moving direction of the plunger.

[0119] According to this injection molding apparatus, the length of the plunger can be easily changed. In one aspect of the injection molding apparatus, the plunger has a recess or a protrusion formed on its periphery, and the control unit may perform a process of detecting the length of the plunger by bringing the recess or the protrusion formed on the plunger into contact with a position reference in the moving direction of the plunger and detecting the torque value of the motor.

[0120] According to this injection molding apparatus, the length of the plunger can be easily detected.

[0121] In one aspect of the injection molding apparatus, the control unit may perform a process of creating control data for controlling the rotation speed of the motor according to the detected length of the plunger, or a process of selecting from among the control data stored in the storage unit.

[0122] According to this injection molding apparatus, suction processing and delivery processing can be performed based on control data corresponding to the length of the plunger.

[0123] In one aspect of the injection molding apparatus, the control unit may perform a process of causing the display unit to display the variable amount of change in the length of the plunger based on the time-series data of the torque value of the motor in the delivery process.

[0124] According to this injection molding apparatus, the user can know the variable amount of change in the length of the plunger.

[0125] In one aspect of the injection molding apparatus, the control unit may perform a process of causing the display unit to display at least one of the maximum injection output, the maximum holding pressure, the longest holding time, and the moving speed of the plunger according to the length of the plunger.

[0126] According to this injection molding apparatus, the user can know at least one of the maximum injection output, the maximum holding pressure, the longest holding time, and the moving speed of the plunger according to the length of the plunger.

[0127] In one aspect of the injection molding apparatus, the support portion is provided between the rotating plate and the plunger and has a wall portion to which the plunger is connected. the power transmission portion is provided between the wall portion and the rotating plate and has a biasing portion that biases the wall portion in a direction approaching the flow path. The nozzle has an opening and closing mechanism for opening and closing the nozzle opening. The opening and closing mechanism is configured such that the nozzle opening opens when the pressure in the flow path is greater than a predetermined pressure. The biasing force by the biasing portion may be smaller than the reaction force of the plunger by the predetermined pressure.

[0128] According to this injection molding apparatus, it is possible to equalize the injection rate of the plasticized material.

[0129] In one aspect of the injection molding apparatus, The control unit performs the suction process while detecting the pressure in the flow path. At the end point of the suction process, the biasing force of the biasing portion may be greater than the reaction force of the plunger by the pressure in the flow path.

[0130] According to this injection molding apparatus, the feeding process can be started in a state where the plunger can be moved by the biasing force of the biasing portion.

Explanation of reference numerals

[0131] 10…Material supply section, 20…Injection section, 30…Mold section, 32…Molding die, 34…Cavity, 36…Movable mold, 38…Fixed mold, 40…Mold clamping section, 42…Mold drive section, 44…Ball screw section, 50…Control device, 52…Memory section, 54…Display section, 56…Control section, 60…Plasticizing section, 62…Screw case, 64…Drive motor, 66…Shaft, 70…Suction and delivery section, 72…Housing, 73…Cylinder, 74…First opening, 75…Second opening, 76…Step surface, 78…Plunger, 79…Motor, 80…Nozzle, 82…Nozzle hole, 84…Nozzle opening, 86…Opening and closing mechanism, 100…Injection molding device, 110…Flat screw, 111…Shaft surface, 112…Groove forming surface, 113…Connection surface, 114…First groove, 115…Central part, 116…Connection part, 117…Material introduction part, 120…Barrel, 122…Opposing surface, 124…Second groove, 126…Communication hole, 130…Heater, 140…Flow path, 150…Power transmission section, 152…Rotating plate, 153…Side surface, 154…Shaft, 156…Support section, 156a…First wall section, 156b…Second wall section, 156c…Third wall section, 156d…Fourth wall section, 157…Hole section, 158…Biasing section, 158a…Contact section, 158b…Spring, 178…First component, 179…Protrusion, 200…Injection molding device, 278…Second component, 279…Insertion hole, 300…Injection molding device, 302…Convex part

Claims

1. A plasticizing unit that plasticizes a material to generate a plasticized material, a nozzle having a nozzle opening through which the plasticized material is discharged from the nozzle opening, a cylinder communicating with the nozzle opening and connected to a flow path through which the plasticized material flows, a plunger that reciprocates within the cylinder, a motor that drives the plunger, and a suction and discharge unit having a power transmission unit that transmits the power of the motor to the plunger, a control unit that controls the motor, comprising: the control unit controls the rotational speed of the motor to move the plunger in a direction away from the flow path, thereby performing a suction process of sucking the plasticized material into the cylinder, controls the rotational speed of the motor to move the plunger in a direction approaching the flow path, thereby performing a discharge process of discharging the plasticized material in the cylinder to the nozzle, performs, the power transmission unit has a rotating plate provided with a rotating shaft at an eccentric position, a support portion that forms a hole through which the rotating shaft passes and supports the plunger, has, the hole extends in the moving direction of the plunger, the support portion swings in the extending direction of the hole as the rotating plate rotates, at the end point of the discharge process, when viewed from the direction of the rotating shaft, the angle formed by the straight line connecting the rotating shaft and the center of the rotating plate and the moving direction of the plunger is greater than 90° and less than 180°, the control unit controls the rotational speed of the motor according to the angle in the discharge process, an injection molding device.

2. In Claim 1, the plunger is composed of a plurality of parts, the plurality of parts are detachable and arranged in the moving direction of the plunger, an injection molding device.

3. In Claim 1, the plunger is formed with a recess or a protrusion around it, the control unit performs a process of detecting the length of the plunger by bringing the recess or the protrusion formed on the plunger into contact with a position indicator in the moving direction of the plunger and detecting the torque value of the motor, an injection molding device.

4. In Claim 3, the control unit performs a process of creating control data for controlling the rotational speed of the motor according to the detected length of the plunger, or a process of selecting from the control data stored in a storage unit, an injection molding device.

5. In claim 1, the control unit performs a process of causing a display unit to display an amount by which the length of the plunger can be changed, based on time-series data of the torque value of the motor in the sending process, in an injection molding apparatus.

6. In claim 1, the control unit performs a process of causing a display unit to display at least one of a maximum injection force, a maximum holding pressure, a longest holding time, and a moving speed of the plunger according to the length of the plunger, in an injection molding apparatus.

7. In any one of claims 1 to 6, the support portion is provided between the rotary plate and the plunger and has a wall portion to which the plunger is connected, the power transmission portion is provided between the wall portion and the rotary plate and has a biasing portion that biases the wall portion in a direction approaching the flow path, the nozzle has an opening / closing mechanism that opens and closes the nozzle opening, the opening / closing mechanism is configured such that the nozzle opening opens when the pressure in the flow path is greater than a predetermined pressure, in an injection molding apparatus, a biasing force by the biasing portion is smaller than a reaction force of the plunger by the predetermined pressure.

8. In claim 7, the control unit performs the suction process while detecting the pressure in the flow path, in an injection molding apparatus, at the end point of the suction process, a biasing force of the biasing portion is greater than a reaction force of the plunger by the pressure in the flow path.

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