Injection molding equipment and mold clamping devices

Abstract

A technology is provided that enables precise adjustment of mold clamping force in an injection molding device equipped with a toggle section. [Solution] The injection molding apparatus comprises an injection unit, a clamping unit, and a control unit. The clamping unit has a toggle fixing unit, a fixed mold mounting unit, a movable mold mounting unit, a motor, a ball screw, a crosshead, and a toggle unit connected to the toggle fixing unit, the movable mold mounting unit, and the crosshead, and which moves the movable mold mounting unit along the clamping direction by moving the crosshead. The toggle unit has a first member connected to the toggle fixing unit via a first rotating shaft, a second member connected to the first member via a second rotating shaft and connected to the movable mold mounting unit via a third rotating shaft, and a third member connected to the crosshead and connected to the first member via a fourth rotating shaft. The length of the line connecting the center of the first rotating shaft and the center of the second rotating shaft in the first member is greater than or equal to the length of the line connecting the center of the second rotating shaft and the center of the third rotating shaft in the second member.

Description

[Technical Field]

[0001] The present disclosure relates to an injection molding apparatus and a mold clamping device. [Background technology]

[0002] Patent Document 1 discloses an injection molding device equipped with a toggle mechanism that opens and closes a mold. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-128014 Summary of the Invention [Problem to be solved by the invention]

[0004] To improve the quality of molded products produced by injection molding, it is necessary to clamp the mold with an appropriate clamping force according to the material used, the shape of the molded product, etc. Therefore, there is a demand for technology that allows for precise adjustment of the clamping force in injection molding machines equipped with a toggle unit that opens and closes the mold. [Means for solving the problem]

[0005] According to a first aspect of the present disclosure, there is provided an injection molding apparatus for injection molding a molded product using a mold consisting of a fixed mold and a movable mold, the injection molding apparatus comprising: an injection unit for injecting material for the molded product into the mold, a mold clamping unit to which the mold is attached and which clamps the mold, and a control unit for controlling the injection unit and the mold clamping unit, the mold clamping unit comprising: a toggle fixing part, a fixed mold mounting part to which the fixed mold is attached, a movable mold mounting part provided between the toggle fixing part and the fixed mold mounting part so as to be movable forward and backward in the mold clamping direction and to which the movable mold is attached, a motor, a ball screw attached to the toggle fixing part and rotated by the drive of the motor, and a control unit for controlling the toggle fixing part and the movable mold mounting part by the rotation of the ball screw. a toggle section connected to the toggle fixing section, the movable mold mounting section, and the crosshead, and configured to move the movable mold mounting section along the mold clamping direction by movement of the crosshead, wherein the toggle section has a first member connected to the toggle fixing section via a first rotating shaft, a second member connected to the first member via a second rotating shaft and connected to the movable mold mounting section via a third rotating shaft, and a third member connected to the crosshead and connected to the first member via a fourth rotating shaft, wherein the length of a line connecting the center of the first rotating shaft and the center of the second rotating shaft in the first member is equal to or greater than the length of a line connecting the center of the second rotating shaft and the center of the third rotating shaft in the second member.

[0006] According to a second aspect of the present disclosure, there is provided a mold clamping device comprising: a toggle fixing portion, a fixed mold mounting portion to which a fixed mold whose position is fixed during mold clamping operation is mounted; a movable mold mounting portion provided between the toggle fixing portion and the fixed mold mounting portion so as to be movable forward and backward in the mold clamping direction and to which a movable mold which moves relatively to the fixed mold during the mold clamping operation is mounted; a motor; a ball screw attached to the toggle fixing portion and rotated by the drive of the motor; a crosshead which moves between the toggle fixing portion and the movable mold mounting portion by the rotation of the ball screw; and a crosshead connected to the toggle fixing portion, the movable mold mounting portion, and the crosshead, which moves the crosshead. and a toggle portion that moves the movable mold mounting portion along the mold clamping direction by movement of the crosshead, the toggle portion having a first member connected to the toggle fixing portion via a first pivot shaft, a second member connected to the first member via a second pivot shaft and connected to the movable mold mounting portion via a third pivot shaft, and a third member connected to the crosshead and connected to the first member via a fourth pivot shaft, wherein the length of a line connecting the center of the first pivot shaft and the center of the second pivot shaft in the first member is equal to or greater than the length of a line connecting the center of the second pivot shaft and the center of the third pivot shaft in the second member. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is an explanatory diagram showing a schematic configuration of an injection molding device. [Figure 2] FIG. 2 is a cross-sectional view showing a schematic configuration of an injection unit. [Figure 3] FIG. 2 is a perspective view showing a schematic configuration of a flat screw. [Figure 4] FIG. 2 is a schematic plan view of the barrel. [Figure 5] FIG. 2 is an explanatory diagram showing a schematic configuration of a mold clamping unit. [Figure 6] 10 is a flowchart of a mold thickness adjustment process executed by a control unit. [Figure 7] FIG. 10 is a diagram showing the state of the mold clamping unit before the mold thickness adjustment process is executed. [Figure 8]10A and 10B are diagrams illustrating the operation of the mold clamping unit in the mold thickness adjustment process. [Figure 9] 10A and 10B are diagrams illustrating the operation of the mold clamping unit in the mold thickness adjustment process. [Figure 10] 10A and 10B are diagrams illustrating the operation of the mold clamping unit in the mold thickness adjustment process. [Figure 11] FIG. 10 is a diagram illustrating the position of the crosshead when the molding die is open. [Figure 12] 10 is a diagram illustrating the position of the crosshead when the molding die is open, in a case where the toggle fixing portion has a recess into which the crosshead cannot be fitted. FIG. [Figure 13] 10 is a diagram showing an example of a toggle portion in which the length of line L1 is longer than the length of line L2. FIG. [Figure 14] 10 is a diagram showing an example of a toggle portion in which the length of line L1 is shorter than the length of line L2. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] A. First embodiment: FIG. 1 is an explanatory diagram showing the schematic configuration of an injection molding apparatus 10. FIG. 1 shows arrows representing mutually orthogonal X, Y, and Z directions. The X and Y directions are parallel to a horizontal plane. The Z direction is parallel to the vertical direction. The X, Y, and Z directions in FIG. 1 and the X, Y, and Z directions in other figures indicate the same directions. When specifying a direction, positive and negative signs are used in combination to indicate the direction, with "+" indicating the positive direction indicated by the arrow and "-" indicating the negative direction opposite to the direction indicated by the arrow.

[0009] Injection molding apparatus 10 includes an injection unit 20, a clamping unit 30, and a control unit 40. Injection molding apparatus 10 performs injection molding of a molded product using a molding die 90 attached to the clamping unit 30. Injection unit 20 and clamping unit 30 are fixed onto a base 11. Injection molding apparatus 10 is a horizontal injection molding apparatus, and injection unit 20 and clamping unit 30 are aligned horizontally. Control unit 40 is housed in base 11.

[0010] The control unit 40 controls the injection unit 20 and the mold clamping unit 30. The control unit 40 is configured by a computer equipped with one or more processors, a memory, and an input / output interface for inputting and outputting signals to and from the outside. The control unit 40 performs various functions, such as executing the process of molding a molded product, by the processor executing programs and instructions loaded onto the main memory. Note that instead of being configured by a computer, the control unit 40 may be realized by a configuration combining multiple circuits for realizing at least some of the functions.

[0011] A metal molding die 90 is attached to the clamping unit 30. The metal molding die 90 is also called a die. The molding die 90 is composed of a fixed die 91 and a movable die 92. The fixed die 91 is a die whose position is fixed during the clamping operation. The movable die 92 is a die that is moved relative to the fixed die 91 during the clamping operation. The movable die 92 is moved in the clamping direction relative to the fixed die 91 by the clamping unit 30. In this embodiment, the clamping direction is the -X direction. Note that the molding die 90 is not limited to being made of metal, and may be made of resin or ceramic. In this specification, the clamping unit 30 is also called a clamping device.

[0012] A hopper 50 into which the material for the molded article is introduced is connected to the injection unit 20. The material for the molded article may be, for example, a thermoplastic resin formed into pellets. Examples of the thermoplastic resin include ABS (acrylonitrile butadiene styrene), PC (polycarbonate), POM (polyacetal), PP (polypropylene), and PBT (polybutylene terephthalate). The material for the molded article may contain metal or ceramic in addition to the thermoplastic resin. The material may be supplied to the injection unit 20 not only through the hopper 50 but also, for example, via a tube through which the material is pressure-fed.

[0013] The injection unit 20 plasticizes at least a portion of the material supplied from the hopper 50 to produce a molding material, and then injects the produced molding material into the mold 90. In this specification, the term "plasticization" includes melting and refers to changing a material from a solid to a fluid state. Specifically, for a material that undergoes glass transition, plasticization refers to raising the temperature of the material above its glass transition point. For a material that does not undergo glass transition, plasticization refers to raising the temperature of the material above its melting point.

[0014] 2 is a cross-sectional view showing a schematic configuration of the injection unit 20. The injection unit 20 includes a plasticizing section 21, a suction delivery section 22, and a nozzle .

[0015] The plasticizing unit 21 plasticizes at least a portion of the material supplied from the hopper 50 to produce a molding material. The plasticizing unit 21 includes a flat screw 110, a barrel 130, and a heater 140. The flat screw 110 is housed in a screw case 111. The flat screw 110 is also called a rotor or simply a screw. The flat screw 110 is driven to rotate around a rotation axis RX within the screw case 111 by a drive motor 112. In this embodiment, the direction of the rotation axis RX is aligned with the X direction. A communication hole 131 is formed in the center of the barrel 130. The communication hole 131 forms at least a portion of a flow path 170 through which the molding material flows. An injection cylinder 151, which will be described later, is connected to the communication hole 131. A check valve 132 is provided in the communication hole 131 upstream of the injection cylinder 151. The rotation of the flat screw 110 by the drive motor 112 and the heating by the heater 140 are controlled by the control unit 40 .

[0016] FIG. 3 is a perspective view showing a schematic configuration of the flat screw 110. The flat screw 110 has a generally cylindrical shape with a height along its central axis that is smaller than its diameter. A spiral groove 123 is formed around a central portion 122 on a groove-forming surface 121 of the flat screw 110 that faces the barrel 130. The groove 123 communicates with a material inlet 124 formed on the side surface of the flat screw 110. Material supplied from the hopper 50 is supplied to the groove 123 through the material inlet 124. The grooves 123 are formed by being separated by ridge portions 125. While FIG. 3 shows an example in which three grooves 123 are formed, the number of grooves 123 may be one or more. The groove 123 is not limited to a spiral shape, but may also be a spiral shape or an involute curve shape, or may have a shape extending in an arc from the central portion 122 to the outer periphery.

[0017] FIG. 4 is a schematic plan view of the barrel 130. The barrel 130 has an opposing surface 133 that faces the groove-forming surface 121 of the flat screw 110. A communication hole 131 is formed in the center of the opposing surface 133. The opposing surface 133 is formed with a plurality of guide grooves 134 that are connected to the communication hole 131 and extend spirally from the communication hole 131 toward the outer periphery. The material supplied to the groove 123 of the flat screw 110 is plasticized between the flat screw 110 and the barrel 130 by the rotation of the flat screw 110 and the heating of the heater 140. Then, the material flows along the groove 123 and the guide groove 134 due to the rotation of the flat screw 110 and is guided to the central portion 122 of the flat screw 110. The material that flows into the central portion 122 flows out from the communication hole 131 provided in the center of the barrel 130 to the suction delivery section 22. Note that the barrel 130 does not necessarily have to be provided with the guide groove 134. Furthermore, the guide groove 134 does not have to be connected to the communication hole 131 .

[0018] As shown in FIG. 2, the suction and delivery unit 22 includes an injection cylinder 151, a plunger 152, and a plunger driver 153. The suction and delivery unit 22 injects the molding material in the injection cylinder 151 into a cavity defined between the fixed mold 91 and the movable mold 92. Under the control of the control unit 40, the suction and delivery unit 22 controls the injection amount, injection speed, and injection pressure of the molding material from the nozzle 23. The injection cylinder 151 is a substantially cylindrical member connected to the communication hole 131 of the barrel 130 and includes a plunger 152 therein. The plunger 152 slides inside the injection cylinder 151 and pressure-feeds the molding material in the injection cylinder 151 to the nozzle 23 provided in the injection unit 20. The plunger 152 is driven by a plunger driver 153, which is configured by a motor.

[0019] Nozzle 23 is formed with a flow path 170. Plunger 152 pressure-feeds the molding material in injection cylinder 151 to nozzle 23, causing the molding material to be injected from nozzle 23 into mold 90. Nozzle 23 may be configured as an open-gate type nozzle or as a valve-gate type nozzle.

[0020] 5 is an explanatory diagram showing a schematic configuration of the mold clamping unit 30. The mold clamping unit 30 clamps the casting mold 90 attached to the mold clamping unit 30. The mold clamping unit 30 has a toggle fixing portion 210, a fixed mold mounting portion 220, a movable mold mounting portion 230, a motor 240, a ball screw 250, a crosshead 260, a toggle portion 270, and a fixed plate moving portion 280.

[0021] The fixed mold mounting part 220 is fixed to the end of the tie bar 201 extending in the X direction on the -X direction side. A fixed mold 91 is attached to the fixed mold mounting part 220. The toggle fixing part 210 is provided on the +X direction side of the fixed mold mounting part 220 so as to be movable along the direction in which the tie bar 201 extends. The movable mold mounting part 230 is provided between the fixed mold mounting part 220 and the toggle fixing part 210 so as to be movable along the direction in which the tie bar 201 extends. In other words, the toggle fixing part 210 and the movable mold mounting part 230 are provided so as to be able to advance and retreat in the mold clamping direction. A movable mold 92 is attached to the movable mold mounting part 230 so as to face the fixed mold 91.

[0022] The toggle fixing portion 210 has a fixing plate 211, a recess 212, and a connecting portion 213. The fixing plate 211 is provided so as to face the movable mold mounting portion 230 with the toggle portion 270 sandwiched therebetween. The recess 212 is provided on the surface of the fixing plate 211 facing the movable mold mounting portion 230 so that at least a part of a crosshead 260 (described later) can be fitted therein. The connecting portion 213 is provided so as to protrude from the fixing plate 211 in the −X direction, which is the mold clamping direction. The connecting portion 213 is provided symmetrically with respect to a horizontal plane including an axis AX of a screw shaft 251 (described later).

[0023] The motor 240 rotates a ball screw 250 (described later). The motor 240 is, for example, a servo motor. The motor 240 is controlled by the control unit 40.

[0024] The ball screw 250 is provided between the toggle fixing portion 210 and the movable mold mounting portion 230. The ball screw 250 has a screw shaft 251 and a nut 252. The screw shaft 251 is attached to a recess 212 of the toggle fixing portion 210 so as to protrude from the fixed plate 211 in the -X direction. The screw shaft 251 is connected to the output shaft of the motor 240 via a coupling. The screw shaft 251 rotates around its axis AX when driven by the motor 240. The direction along the axis AX is the X direction. The nut 252 is provided movably along the screw shaft 251 and moves in the X direction as the screw shaft 251 rotates. A crosshead 260 is connected to the nut 252. A portion of the nut 252 protrudes toward the toggle fixing portion 210 relative to the crosshead 260, but does not protrude toward the movable mold mounting portion 230 relative to the crosshead 260.

[0025] The crosshead 260 is fixed to the nut 252. Therefore, when the nut 252 moves in the X direction as the screw shaft 251 rotates, the crosshead 260 also moves in the X direction together with the nut 252. In other words, the crosshead 260 moves in the X direction between the toggle fixing part 210 and the movable die mounting part 230 as the ball screw 250 rotates.

[0026] The toggle part 270 is connected to the toggle fixing part 210, the movable die mounting part 230, and the crosshead 260. The toggle part 270 has a first member 271, a second member 272, and a third member 273. The first member 271, the second member 272, and the third member 273 are provided symmetrically with respect to a horizontal plane including the axis line AX of the screw shaft 251.

[0027] The first member 271 is connected to the connection portion 213 of the toggle fixing portion 210 via a first rotation axis BX1. The direction along the axis of the first rotation axis BX1 is the Y direction. The first member 271 is provided so as to be rotatable within the XZ plane around the first rotation axis BX1. The first member 271 is also called a crank.

[0028] One end of the second member 272 is connected to the first member 271 via a second rotation axis BX2, and the other end is connected to the movable mold attachment part 230 via a third rotation axis BX3. The direction along the axes of the second rotation axis BX2 and the third rotation axis BX3 is the Y direction. The second member 272 is provided so as to be rotatable relative to the first member 271 in the XZ plane around the second rotation axis BX2. The second member 272 is also provided so as to be rotatable relative to the movable mold attachment part 230 in the XZ plane around the third rotation axis BX3. The second member 272 is also called a connecting rod.

[0029] One end of the third member 273 is connected to the first member 271 via a fourth rotation axis BX4, and the other end is connected to the crosshead 260 via a fifth rotation axis BX5. The direction along the axes of the fourth rotation axis BX4 and the fifth rotation axis BX5 is the Y direction. The third member 273 is provided so as to be rotatable relative to the first member 271 in the XZ plane around the fourth rotation axis BX4. The third member 273 is also provided so as to be rotatable relative to the crosshead 260 in the XZ plane around the fifth rotation axis BX5. The third member 273 is also called a link.

[0030] The length of line L1 connecting the center of first rotation axis BX1 and the center of second rotation axis BX2 in first member 271 is equal to or greater than the length of line L2 connecting the center of second rotation axis BX2 and the center of third rotation axis BX3 in second member 272. Fig. 5 shows a case where the lengths of line L1 and line L2 are equal. Furthermore, the length of line L3 connecting the end of connecting portion 213 that contacts fixed plate 211 and the center of first rotation axis BX1 is longer than the length of line L1. Here, the direction along line L3 is the X direction.

[0031] When the crosshead 260 moves in the -X direction, each member of the toggle unit 270 rotates around each rotation axis, causing the movable mold mount 230 to move in the -X direction. This causes the molding die 90 to be clamped. When the crosshead 260 moves in the +X direction, each member of the toggle unit 270 rotates around each rotation axis, causing the movable mold mount 230 to move in the +X direction. This causes the molding die 90 to be opened. In other words, the toggle unit 270 moves the movable mold mount 230 in the clamping direction by moving the crosshead 260. Hereinafter, the rotation of each member of the toggle unit 270 around each rotation axis is also referred to as the toggle unit 270 operating.

[0032] The fixed plate moving unit 280 moves the toggle fixed unit 210 in the mold clamping direction. The fixed plate moving unit 280 has a base 281, a first gear 282, a second gear 283, and a fixed plate moving motor (not shown). The base 281 is attached to the +X direction side of the fixed plate 211. The first gear 282 and the second gear 283 are attached to the +X direction side of the base 281 so that their axes are aligned in the X direction. The first gear 282 is connected to the fixed plate moving motor and rotates around its axis when driven by the fixed plate moving motor. The fixed plate moving motor is controlled by the control unit 40. The second gear 283 meshes with the first gear 282. The second gear 283 has a through hole that penetrates the second gear 283 in the X direction. A screw thread is formed on the inner surface of the through hole. A tie bar 201 is located within the through hole. The threads on the inner surface of the through hole are threaded into a screw groove formed on the surface of the tie bar 201. Therefore, when the first gear 282 rotates about its axis, the second gear 283 rotates about its axis, and the fixed plate moving part 280 moves in the X direction along the tie bar 201. As a result, the toggle fixing part 210, motor 240, ball screw 250, crosshead 260, toggle part 270, and movable mold mounting part 230 move together with the fixed plate moving part 280 in the X direction as a unit.

[0033] The control unit 40 drives the motor 240 to control the position of the crosshead 260, thereby operating the toggle unit 270 and clamping and opening the fixed mold 91 and the movable mold 92. The control unit 40 also drives the fixed plate movement motor to control the position of the fixed plate movement unit 280, thereby moving the toggle fixing unit 210 and adjusting the clamping force.

[0034] FIG. 6 is a flowchart of the mold thickness adjustment process executed by the control unit 40. The mold thickness adjustment process is a process executed to adjust the clamping force during mold clamping. The mold thickness adjustment process is executed when the casting mold 90 is first attached to the clamping unit 30 and when the casting mold 90 attached to the clamping unit 30 is replaced. FIGS. 7 to 10 are diagrams illustrating the operation of the clamping unit 30 in the mold thickness adjustment process. The mold thickness adjustment process will be described below with reference to FIGS. 5 to 10. Hereinafter, movement of each part of the clamping unit 30 in the -X direction, which is the clamping direction, will be referred to as "forward," and movement in the +X direction, which is the opposite direction to the clamping direction, will be referred to as "rearward."

[0035] 7 shows the state of the mold clamping unit 30 before the mold thickness adjustment process is performed. Before the mold thickness adjustment process is performed, the fixed mold 91 and the movable mold 92 are spaced apart from each other.

[0036] In step S10 of FIG. 6, the control unit 40 drives the motor 240 to advance the crosshead 260 to a position where the first bending angle C is 180°. Here, the first bending angle C is the angle between the line L1 and the line L2 on the side farther from the ball screw 250 in the Z direction. FIG. 5 shows a state where step S10 is executed and the first bending angle C is 180°. Note that the control unit 40 does not have to advance the crosshead 260 to a position where the first bending angle C is exactly 180°. It is preferable that the control unit 40 advance the crosshead 260 to a position where the first bending angle C is equal to or greater than 179° and equal to or less than 180°.

[0037] In step S20, the control unit 40 drives the fixed plate moving motor to move the toggle fixing unit 210 forward to a position where the fixed die 91 and the movable die 92 come into contact with each other. FIG. 8 shows a state where step S20 has been executed and the fixed die 91 and the movable die 92 have come into contact with each other. In step S20, the control unit 40 does not change the position of the crosshead 260. Therefore, the first bending angle C in step S20 is equal to the first bending angle C in step S10.

[0038] In step S30, the control unit 40 drives the motor 240 to retract the crosshead 260 so that the movable mold attachment portion 230 retracts a predetermined retraction amount. The predetermined retraction amount is determined by the thickness, shape, etc. of the molding mold 90 attached to the mold clamping unit 30. As a result, the movable mold 92 retracts by the predetermined retraction amount, and the fixed mold 91 and the movable mold 92 are separated. FIG. 9 shows a state in which step S30 has been executed and the movable mold 92 has retracted. As shown in FIG. 9, the retraction of the crosshead 260 causes the first bending angle C to be smaller than 180°. At this time, it is preferable that the first bending angle C be equal to or greater than 150° and equal to or less than 175°.

[0039] In step S40, the control unit 40 drives the fixed plate moving motor to move the toggle fixing unit 210 forward to a position where the fixed mold 91 and the movable mold 92 come into contact with each other. FIG. 10 shows a state where step S40 has been executed and the fixed mold 91 and the movable mold 92 have come into contact with each other. In step S40, the control unit 40 does not change the position of the crosshead 260. Therefore, the first bending angle C in step S40 is equal to the first bending angle C in step S30. The position of the toggle fixing unit 210 in the mold clamping direction is fixed to the position when step S40 is completed. The mold thickness adjustment process is executed as described above.

[0040] After the above-described mold thickness adjustment process is performed, the molded product is injection molded. In injection molding of the molded product, the control unit 40 drives the motor 240 to move the crosshead 260 forward from the state shown in Fig. 10 to a position where the first bending angle C is 180°. This causes the fixed mold 91 and the movable mold 92 to be clamped together at high pressure. With the fixed mold 91 and the movable mold 92 clamped together at high pressure, the injection unit 20 injects the molding material into the mold 90.

[0041] After the injection molding of the molded product is completed, the molding die 90 is opened. The control unit 40 drives the motor 240 to move the crosshead 260 backward, thereby opening the molding die 90. FIG. 11 is a diagram illustrating the position of the crosshead 260 when the molding die 90 is open. As shown in FIG. 11 , when the molding die 90 is open, a portion of the nut 252 protruding toward the toggle fixing portion 210 and a portion of the crosshead 260 fit into the recess 212. When the molding die 90 is open, the crosshead 260 is positioned closest to the toggle fixing portion 210. In other words, when the crosshead 260 is positioned closest to the toggle fixing portion 210, a portion of the crosshead 260 fits into the recess 212. Note that when the crosshead 260 is positioned closest to the toggle fixing portion 210, the entire crosshead 260 may fit into the recess 212.

[0042] 12 is a diagram illustrating the position of the crosshead 260 when the molding die 90 is open, when the toggle fixing part 210 has a recess 212a into which the crosshead 260 cannot be fitted. In this case, when the molding die 90 is open, a portion of the nut 252 protruding toward the toggle fixing part 210 fits into the recess 212a, but the crosshead 260 does not fit into the recess 212a. Therefore, as shown in FIG. 11, when the toggle fixing part 210 has the recess 212 into which at least a portion of the crosshead 260 can fit, the amount of retraction of the crosshead 260 when the mold is opened is greater than when the toggle fixing part 210 has the recess 212a into which the crosshead 260 cannot fit.

[0043] According to the first embodiment described above, the length of line L1 connecting the center of the first rotation axis BX1 and the center of the second rotation axis BX2 in the first member 271 is equal to or greater than the length of line L2 connecting the center of the second rotation axis BX2 and the center of the third rotation axis BX3 in the second member 272. When the length of line L1 is equal to or greater than the length of line L2, as in this embodiment, the clamping force used when injection molding a molded product can be adjusted more precisely than when the length of line L1 is less than the length of line L2. The reason for this will be explained below. Note that hereinafter, the clamping force used when injection molding a molded product is simply referred to as the clamping force.

[0044] The mold clamping force is determined by the amount of retraction of the movable mold mount 230, which is retracted in step S30 of the mold thickness adjustment process. Therefore, in order to precisely adjust the mold clamping force, it is necessary to precisely adjust the amount of retraction of the movable mold mount 230 in step S30. Since the movable mold mount 230 retracts as the toggle part 270 operates when the crosshead 260 retracts, the smaller the amount of retraction of the movable mold mount 230 relative to the amount of retraction of the crosshead 260, the more precisely the amount of retraction of the movable mold mount 230 can be adjusted.

[0045] Below, we will explain, using specific examples, the amount of retraction of the movable mount 230 when the crosshead 260 is retracted the same amount, for both the case where the length of line L1 is longer than the length of line L2 and the case where the length of line L1 is shorter than the length of line L2. Hereinafter, the length of line L1 is designated b, and the length of line L2 is designated a. FIG. 13 is a diagram showing an example of a toggle section 270c in which the length b of line L1 is longer than the length a of line L2. In FIG. 13, a = 50 mm, b = 65 mm. FIG. 14 is a diagram showing an example of a toggle section 270d in which the length b of line L1 is shorter than the length a of line L2. In FIG. 14, a = 80 mm, b = 65 mm.

[0046] When the crosshead 260 is retracted by the retraction amount x from the position where the first bending angle C is 180°, the retraction amount xp of the movable mold mount 230 is expressed by the following formula (1). xp=(a+b)cosθ1-bcosθ2-acosθ3...(1) In formula (1), θ2 is the angle between the X direction, which is the direction along the mold clamping direction, and the direction along line L1 in a state where the crosshead 260 has retracted by the retraction amount x. θ1 is the value of θ2 when the first bending angle C is 180°, i.e., the value of θ2 before the crosshead 260 retracts. θ3 is the angle between the X direction, which is the direction along the mold clamping direction, and the direction along line L2 in a state where the crosshead 260 has retracted by the retraction amount x. θ1, θ2, and θ3 are determined by the length b of line L1, the length a of line L2, and the retraction amount x of the crosshead 260.

[0047] In the following, for the examples shown in FIGS. 13 and 14, the retraction amount xp of the movable mold mount 230 when the crosshead 260 retracts 10 mm from the position where the first bending angle C is 180° is calculated. First, in the example shown in FIG. 13, a = 50 mm, b = 65 mm, and x = 10 mm. At this time, θ1 = 5.5°, θ2 = 9.7°, and θ3 = 0.07°. Substituting these values ​​into equation (1), xp = 0.3998 mm. That is, when the length of line L1 is 65 mm, the length of line L2 is 50 mm, and the retraction amount of the crosshead 260 is 10 mm, the retraction amount xp of the movable mold mount 230 is 0.3998 mm. Next, in the example shown in FIG. 14, a = 80 mm, b = 65 mm, and x = 10 mm. At this time, θ1 = 5.5°, θ2 = 11.2°, and θ3 = 1.2°. Substituting these values ​​into equation (1), xp = 0.5879 mm is obtained. That is, when the length of line L1 is 65 mm, the length of line L2 is 80 mm, and the retraction amount of the crosshead 260 is 10 mm, the retraction amount xp of the movable mold mount 230 is 0.5879 mm. Therefore, when the length of line L1 is longer than the length of line L2, the retraction amount of the movable mold mount 230 when the crosshead 260 is retracted by the same retraction amount is smaller than when the length of line L1 is shorter than the length of line L2. Therefore, when the length of line L1 is equal to or greater than the length of line L2, the mold clamping force can be adjusted more precisely than when the length of line L1 is shorter than the length of line L2.

[0048] Furthermore, in this embodiment, the toggle fixing part 210 is provided with a recess 212 into which at least a part of the crosshead 260 can fit. Therefore, the amount of retraction of the crosshead 260 when the mold is opened can be increased compared to when the toggle fixing part 210 does not have the recess 212. This allows the amount of opening and closing of the forming mold 90 to be increased.

[0049] Furthermore, in this embodiment, when the crosshead 260 is positioned closest to the toggle fixing part 210, at least a portion of the crosshead 260 fits into the recess 212. Therefore, the amount of retraction of the crosshead 260 when the mold is opened can be increased compared to when the toggle fixing part 210 does not have the recess 212. This allows the amount of opening and closing of the molding die 90 to be increased.

[0050] Furthermore, in this embodiment, the length of line L3 connecting the end of connecting portion 213 that contacts fixed plate 211 and the center of first pivot axis BX1 is longer than the length of line L1 connecting the center of first pivot axis BX1 and the center of second pivot axis BX2 of first member 271. When line L3 is longer than line L1, first member 271 can rotate about first pivot axis BX1 until second bending angle D becomes smaller when crosshead 260 retracts, compared to when line L3 is shorter than line L1. Here, second bending angle D is the angle between line L1 and line L3 on the side closer to ball screw 250 in the Z direction, as shown in FIG. 11 . Therefore, in this embodiment, the amount of retraction of crosshead 260 during mold opening can be increased compared to when line L3 is shorter than line L1. This increases the amount of opening and closing of molding die 90.

[0051] Furthermore, in this embodiment, a portion of the nut 252 protrudes toward the toggle fixing portion 210 relative to the crosshead 260, and does not protrude toward the movable mounting portion 230 relative to the crosshead 260. Therefore, compared to when a portion of the nut 252 protrudes toward the movable mounting portion 230 relative to the crosshead 260, the possibility of the nut 252 interfering with members such as the toggle portion 270 can be reduced.

[0052] Furthermore, in this embodiment, the control unit 40 controls the fixed plate moving unit 280 to move the toggle fixing unit 210 and adjust the clamping force. Therefore, the clamping force can be adjusted to a clamping force appropriate for the molding die 90 attached to the clamping unit 30. Furthermore, even if the molding die 90 attached to the clamping unit 30 is replaced and the thickness or shape of the molding die 90 changes, the clamping force can be adjusted. Therefore, appropriate mold clamping can be performed.

[0053] B. Other Embodiments: (B-1) In the above embodiment, the toggle fixing part 210 is provided with a recess 212 into which at least a part of the crosshead 260 can be fitted. However, the toggle fixing part 210 does not necessarily have to be provided with the recess 212.

[0054] (B-2) In the above embodiment, when the crosshead 260 is positioned closest to the toggle fixing portion 210, at least a portion of the crosshead 260 fits into the recess 212. In contrast, when the crosshead 260 is positioned closest to the toggle fixing portion 210, the crosshead 260 does not have to fit into the recess 212.

[0055] (B-3) In the above embodiment, the length of line L3 connecting the end of connecting portion 213 that contacts fixed plate 211 to the center of first rotation axis BX1 is longer than the length of line L1 connecting the center of first rotation axis BX1 and the center of second rotation axis BX2 in first member 271. In contrast, the length of line L3 does not have to be longer than the length of line L1.

[0056] (B-4) In the above embodiment, a portion of the nut 252 protrudes toward the toggle fixing portion 210 relative to the crosshead 260, and does not protrude toward the movable mounting portion 230 relative to the crosshead 260. In contrast, a portion of the nut 252 does not have to protrude toward the toggle fixing portion 210 relative to the crosshead 260. Furthermore, a portion of the nut 252 may protrude toward the movable mounting portion 230 relative to the crosshead 260.

[0057] (B-5) In the above embodiment, the mold clamping unit 30 has the fixed plate moving part 280, and the control part 40 controls the fixed plate moving part 280 to move the toggle fixing part 210 and adjust the mold clamping force. In contrast, the mold clamping unit 30 does not have to have the fixed plate moving part 280.

[0058] C. Other forms: The present disclosure is not limited to the above-described embodiments and can be realized in various forms without departing from the spirit thereof. For example, the present disclosure can also be realized in the following forms. The technical features in the above embodiments corresponding to the technical features in each form described below can be appropriately replaced or combined to solve some or all of the problems of the present disclosure or to achieve some or all of the effects of the present disclosure. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted.

[0059] (1) According to a first aspect of the present disclosure, there is provided an injection molding apparatus for injection molding a molded product using a mold consisting of a fixed mold and a movable mold, the injection molding apparatus comprising: an injection unit for injecting material for the molded product into the mold, a mold clamping unit to which the mold is attached and which clamps the mold, and a control unit for controlling the injection unit and the mold clamping unit, the mold clamping unit comprising: a toggle fixing part, a fixed mold mounting part to which the fixed mold is attached, a movable mold mounting part provided between the toggle fixing part and the fixed mold mounting part so as to be movable forward and backward in the mold clamping direction and to which the movable mold is attached, a motor, a ball screw attached to the toggle fixing part and rotated by the drive of the motor, and a control unit for controlling the toggle fixing part and the movable mold mounting part by the rotation of the ball screw. a toggle section connected to the toggle fixing section, the movable mold mounting section, and the crosshead, and configured to move the movable mold mounting section along the mold clamping direction by movement of the crosshead, wherein the toggle section has a first member connected to the toggle fixing section via a first rotating shaft, a second member connected to the first member via a second rotating shaft and connected to the movable mold mounting section via a third rotating shaft, and a third member connected to the crosshead and connected to the first member via a fourth rotating shaft, wherein the length of a line connecting the center of the first rotating shaft and the center of the second rotating shaft in the first member is equal to or greater than the length of a line connecting the center of the second rotating shaft and the center of the third rotating shaft in the second member. According to this configuration, the amount of retraction of the movable mold mount relative to the amount of retraction of the crosshead can be made smaller than when the length of the line connecting the center of the first pivot shaft and the center of the second pivot shaft in the first member is less than the length of the line connecting the center of the second pivot shaft and the center of the third pivot shaft in the second member.Since the mold clamping force is determined by the amount of retraction of the movable mold mount, this configuration allows for precise adjustment of the mold clamping force when injection molding a molded product.

[0060] (2) In the above embodiment, the toggle fixing portion may be provided with a recess into which at least a portion of the crosshead can be fitted. According to this configuration, the amount of retraction of the crosshead when the mold is opened can be increased compared to when no recess is provided in the toggle fixing portion.

[0061] (3) In the above embodiment, when the crosshead is positioned closest to the toggle fixing portion, at least a portion of the crosshead may fit into the recess. According to this configuration, the amount of retraction of the crosshead when the mold is opened can be increased compared to when no recess is provided in the toggle fixing portion.

[0062] (4) In the above embodiment, the toggle fixing portion has a fixing plate and a connecting portion that protrudes from the fixing plate in the mold clamping direction and is connected to the first member via the first rotating shaft, and the length of a line connecting the end of the connecting portion that contacts the fixing plate and the center of the first rotating shaft may be longer than the length of a line connecting the center of the first rotating shaft and the center of the second rotating shaft in the first member. According to this configuration, the amount of recoil of the crosshead when the mold is opened can be increased compared to when the length of the line connecting the end of the connection portion that contacts the fixed plate and the center of the first pivot shaft is shorter than the length of the line connecting the center of the first pivot shaft and the center of the second pivot shaft in the first member.

[0063] (5) In the above embodiment, the ball screw has a screw shaft and a nut that is movably arranged along the screw shaft and connected to the crosshead, and a portion of the nut may protrude toward the toggle fixing portion relative to the crosshead and may not protrude toward the movable mounting portion relative to the crosshead. According to this configuration, the possibility of the nut interfering with members such as the toggle portion can be reduced compared to when a portion of the nut protrudes toward the movable mounting portion relative to the crosshead.

[0064] (6) In the above embodiment, the mold clamping unit may have a fixed plate moving part that moves the toggle fixing part along the mold clamping direction, and the control part may control the fixed plate moving part to move the toggle fixing part and adjust the mold clamping force. According to this embodiment, the mold clamping force can be adjusted to a mold clamping force appropriate for the molding die attached to the mold clamping unit.

[0065] (7) According to a second aspect of the present disclosure, there is provided a mold clamping device comprising: a toggle fixing portion; a fixed mold mounting portion to which a fixed mold whose position is fixed during mold clamping operation is mounted; a movable mold mounting portion that is provided between the toggle fixing portion and the fixed mold mounting portion so as to be movable forward and backward in the mold clamping direction and to which a movable mold that moves relative to the fixed mold during the mold clamping operation is mounted; a motor; a ball screw that is attached to the toggle fixing portion and rotates when driven by the motor; a crosshead that moves between the toggle fixing portion and the movable mold mounting portion by the rotation of the ball screw; and a crosshead that is connected to the toggle fixing portion, the movable mold mounting portion, and the crosshead and moves the crosshead. and a toggle portion that moves the movable mold mounting portion along the mold clamping direction by movement of the crosshead, the toggle portion having a first member connected to the toggle fixing portion via a first pivot shaft, a second member connected to the first member via a second pivot shaft and connected to the movable mold mounting portion via a third pivot shaft, and a third member connected to the crosshead and connected to the first member via a fourth pivot shaft, wherein the length of a line connecting the center of the first pivot shaft and the center of the second pivot shaft in the first member is equal to or greater than the length of a line connecting the center of the second pivot shaft and the center of the third pivot shaft in the second member. According to this configuration, the amount of retraction of the movable mold mount relative to the amount of retraction of the crosshead can be made smaller than when the length of the line connecting the center of the first pivot shaft and the center of the second pivot shaft in the first member is less than the length of the line connecting the center of the second pivot shaft and the center of the third pivot shaft in the second member.Since the mold clamping force is determined by the amount of retraction of the movable mold mount, this configuration allows for precise adjustment of the mold clamping force when injection molding a molded product. [Explanation of symbols]

[0066] 10...injection molding apparatus, 11...base, 20...injection unit, 21...plasticizing section, 22...suction delivery section, 23...nozzle, 30...mold clamping unit, 40...control section, 50...hopper, 90...molding mold, 91...fixed mold, 92...movable mold, 110...flat screw, 111...screw case, 112...drive motor, 121...groove forming surface, 122...center section, 123...groove, 124...material inlet, 125...ridge section, 130...barrel, 131...communicating hole, 132...check valve, 133...opposing surface, 134...guide groove, 140...heater, 151...injection cylinder, 152...plunger, 153...plunger drive section, 170...flow path, 201...ta driver, 210...toggle fixing portion, 211...fixed plate, 212, 212a...recess, 213...connection portion, 220...fixed mounting portion, 230...movable mounting portion, 240...motor, 250...ball screw, 251...screw shaft, 252...nut, 260...crosshead, 270, 270c, 270d...toggle portion, 271...first member, 272...second member, 273...third member, 280...fixed plate moving portion, 281...base, 282...first gear, 283...second gear, AX...axis, BX1...first rotating axis, BX2...second rotating axis, BX3...third rotating axis, BX4...fourth rotating axis, BX5...fifth rotating axis, C...first bending angle, D...second bending angle, RX...rotating axis

Claims

1. An injection molding apparatus for injection molding a molded product using a mold consisting of a fixed mold and a movable mold, an injection unit that injects material for the molded article into the mold; a mold clamping unit to which the molding die is attached and which clamps the molding die; a control unit that controls the injection unit and the mold clamping unit, The mold clamping unit includes: A toggle fixing portion; a fixed mold mounting portion to which the fixed mold is attached; a movable mold mounting portion provided between the toggle fixing portion and the fixed mold mounting portion so as to be movable back and forth in a mold clamping direction, and to which the movable mold is attached; A motor and a ball screw attached to the toggle fixing portion and rotated by the drive of the motor; a crosshead that moves between the toggle fixing portion and the movable die mounting portion by rotation of the ball screw; a toggle part connected to the toggle fixing part, the movable mold mounting part, and the crosshead, and configured to move the movable mold mounting part along the mold clamping direction by movement of the crosshead, The toggle portion is a first member connected to the toggle fixing portion via a first rotation shaft; a second member connected to the first member via a second rotation shaft and connected to the movable die mounting portion via a third rotation shaft; a third member connected to the crosshead and connected to the first member via a fourth rotation shaft; a length of a line connecting the center of the first rotation shaft and the center of the second rotation shaft in the first member is equal to or greater than a length of a line connecting the center of the second rotation shaft and the center of the third rotation shaft in the second member; Injection molding equipment.

2. 2. The injection molding apparatus according to claim 1, The toggle fixing portion is provided with a recess into which at least a portion of the crosshead can be fitted. Injection molding equipment.

3. 3. The injection molding apparatus according to claim 2, When the crosshead is positioned closest to the toggle locking portion, at least a portion of the crosshead fits into the recess. Injection molding equipment.

4. 2. The injection molding apparatus according to claim 1, The toggle fixing portion is A fixing plate and a connection portion provided to protrude from the fixed plate in the mold clamping direction and connected to the first member via the first rotation shaft, a length of a line connecting an end of the connection portion that contacts the fixed plate and the center of the first rotation shaft is longer than a length of a line connecting the center of the first rotation shaft and the center of the second rotation shaft of the first member; Injection molding equipment.

5. 2. The injection molding apparatus according to claim 1, The ball screw A screw shaft, a nut provided movably along the screw shaft and connected to the crosshead, a part of the nut protrudes from the crosshead toward the toggle fixing portion, and does not protrude from the crosshead toward the movable mounting portion; Injection molding equipment.

6. 2. The injection molding apparatus according to claim 1, the mold clamping unit has a fixing plate moving part that moves the toggle fixing part along the mold clamping direction, the control unit controls the fixing plate moving unit to move the toggle fixing unit and adjust the mold clamping force. Injection molding equipment.

7. A toggle fixing portion; a fixed mold mounting portion to which a fixed mold whose position is fixed during a mold clamping operation is mounted; a movable mold mounting portion provided between the toggle fixing portion and the fixed mold mounting portion so as to be movable back and forth in a mold clamping direction, and to which a movable mold is attached which is moved relatively to the fixed mold during the mold clamping operation; A motor and a ball screw attached to the toggle fixing portion and rotated by the drive of the motor; a crosshead that moves between the toggle fixing portion and the movable die mounting portion by rotation of the ball screw; a toggle part connected to the toggle fixing part, the movable mold mounting part, and the crosshead, and configured to move the movable mold mounting part along the mold clamping direction by movement of the crosshead, The toggle portion is a first member connected to the toggle fixing portion via a first rotation shaft; a second member connected to the first member via a second rotation shaft and connected to the movable die mounting portion via a third rotation shaft; a third member connected to the crosshead and connected to the first member via a fourth rotation shaft; a length of a line connecting the center of the first rotation shaft and the center of the second rotation shaft in the first member is equal to or greater than a length of a line connecting the center of the second rotation shaft and the center of the third rotation shaft in the second member; Mold clamping device.

Images