Injection molding machine

Abstract

To provide an injection molding machine that can improve the stability of the quality of thermoplastic material after molding.SOLUTION: An injection molding machine comprises: a barrel (100) extending axially and into which thermoplastic material is supplied; a torpedo (120) extending axially and inserted into the barrel; a heater (132) provided on at least one of the barrel and the torpedo; a supply device (30) for supplying thermoplastic material into a space enclosed by an inner wall surface of the barrel and the outer peripheral surface of the torpedo; a hollow plunger (110) interposed between the barrel and the torpedo for pressing and melting the thermoplastic material supplied from the supply device under heating by the heater; a drive mechanism (150) for driving the torpedo and the plunger to reciprocate independently in an axial direction; and a control device (20) that controls operation of the drive mechanism to update a pressing force by the plunger for each shot or multiple shots, which are units of the injection operation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an injection molding machine for injection molding a thermoplastic material. [Background technology]

[0002] 2. Description of the Related Art Conventionally, injection molding machines are known that heat, push, melt, and inject thermoplastic materials.

[0003] In this regard, Patent Document 1 discloses an injection molding machine that includes a barrel, a plunger for inserting a thermoplastic material, a rod that passes through a through-hole in the plunger and is movable in the axial direction, and a torpedo connected to the rod. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6657550 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technology described in Patent Document 1 has a problem in that the pressing force when the thermoplastic material is pressed in by the plunger to melt it can be set to only one level, which makes the quality of the material unstable.

[0006] The present invention has been made in view of the above problems, and its object is to provide an injection molding machine that can improve the stability of the quality of the thermoplastic material after molding. [Means for solving the problem]

[0007] In order to solve the above problems, the injection molding machine of the present invention includes: a barrel extending in an axial direction and into which a thermoplastic material is supplied; a torpedo extending in the axial direction and inserted into the barrel; a heater provided in at least one of the barrel and the torpedo; a supply device that supplies the thermoplastic material into a space surrounded by an inner wall surface of the barrel and an outer peripheral surface of the torpedo; a hollow plunger that is interposed between the barrel and the torpedo and that pushes and melts the thermoplastic material supplied from the supply device under the heat of the heater; a drive mechanism that drives the torpedo and the plunger independently to move back and forth in the axial direction; and a control device that controls the operation of the drive mechanism to update the pressing force of the plunger for each shot or for each set of multiple shots that is a unit of injection operation.

[0008] The injection molding machine of the present invention further includes a pressure measuring unit provided at the axial end of the torpedo for measuring the pressure applied to the torpedo, and the control device updates the pressing force based on at least the pressure measured by the pressure measuring unit during the pushing operation of the plunger.

[0009] In addition, the injection molding machine of the present invention further includes a position measurement unit that measures the position of the plunger, and the control device updates the pressing force based on at least the position or the amount of change in position over time measured by the position measurement unit during the pushing operation of the plunger.

[0010] In addition, the injection molding machine of the present invention further includes a temperature measurement unit that measures the temperature of the barrel or the torpedo, and the control device updates the pressing force based on at least the temperature measured by the temperature measurement unit during the pushing operation of the plunger.

[0011] The injection molding machine of the present invention further includes a pressure measuring unit provided at the axial end of the torpedo for measuring the pressure applied to the torpedo, a position measuring unit for measuring the position of the plunger, and a temperature measuring unit for measuring the temperature of the torpedo, and the control device calculates the filling rate of the thermoplastic material in the barrel based on the pressure measured by the pressure measuring unit and the position measured by the position measuring unit during the plunger pushing operation, and updates the pressing force based on the temperature measured by the temperature measuring unit during the plunger pushing operation, the filling rate, and information indicating a predetermined type or size of the thermoplastic material. [Effects of the Invention]

[0012] According to the present invention, the injection molding machine can improve the stability of the quality of the thermoplastic material after molding. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram showing the overall configuration of an injection molding machine according to an embodiment of the present invention; [Figure 2] FIG. 2 is a diagram showing the details of the configuration of the drive mechanism shown in FIG. 1 together with a control device, a plunger, and a torpedo. [Figure 3] FIG. 2 is a diagram illustrating a functional configuration of a control device illustrated in FIG. [Figure 4] 2 is an example of a flowchart showing a series of processing steps of the injection molding machine shown in FIG. 1. [Figure 5A] 2 is a cross-sectional view of a part of the injection molding machine showing the operation of the supply process of the injection unit shown in FIG. 1. FIG. [Figure 5B] 2 is a cross-sectional view of a part of the injection molding machine, illustrating the operation of the plasticizing step of the injection unit shown in FIG. 1. FIG. [Figure 5C] 2 is a cross-sectional view of a part of the injection molding machine showing the operation of the injection process of the injection unit shown in FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components and steps in each drawing will be assigned the same reference numerals as much as possible, and redundant description will be omitted. Furthermore, the term "part" may be replaced with other terms such as unit, module, device, or element.

[0015] <Overall structure> 1 is a diagram showing the overall configuration of an injection molding machine 1 according to this embodiment. As shown in Fig. 1, the injection molding machine 1 is mainly configured to include, for example, an injection unit 10, a control unit 20, and a supply unit 30.

[0016] The injection device 10 heats and melts the thermoplastic material 3 (see FIG. 5A ), which will be described later, supplied from the supply device 30, and then injects it into a molding die in accordance with the operational control of the control device 20. The injection device 10 is mainly configured to include, for example, a barrel 100, a plunger 110, a torpedo 120, heaters 131 and 132, a pressure measuring unit 141, a position measuring unit 142, a temperature measuring unit 144, and a drive mechanism 150.

[0017] The barrel 100 has a supply port 102 on its side through which the thermoplastic material 3 is supplied, and an injection port 104 on its bottom through which the thermoplastic material 3 is injected, and is formed into a bottomed cylindrical shape extending along an axis A (see FIG. 5A). The barrel 100 also has a space 103 inside for forcing, melting, and injecting the thermoplastic material 3. The barrel 100 also has a heater 132 on its outer peripheral side for heating the barrel 100.

[0018] The torpedo 120 is a component that extends in the direction of axis A, is inserted into the barrel 100, and incorporates a heater 131. The torpedo 120 conducts heat generated by the heater 131 to the thermoplastic material 3. The torpedo 120 also injects the thermoplastic material 3 plasticized by the plunger 110 from the injection port 104. The torpedo 120 is provided to be movable back and forth along its axial direction (the direction of axis A) and moves along axis A according to a force transmitted from the drive mechanism 150. The torpedo 120 has, for example, a rod-shaped portion extending along axis A, a tip portion connected to one end of the rod-shaped portion in the downward direction (toward the injection port 104), and a base portion connected to the other end of the rod-shaped portion in the upward direction (the direction opposite to the injection port 104). The tip portion is tapered from the downward direction to the upward direction along axis A, and the outer periphery of the lower end is formed in a gear shape. The rod-shaped portion is formed to extend in the direction of axis A, and is provided therein with heater 131 for heating torpedo 120. The rod-shaped portion is provided so that one end connected to the tip end is located inside barrel 100, and the other end connected to the base end is located outside barrel 100. The rod-shaped portion penetrates between the top and bottom surfaces of plunger 110 and is provided so as to be movable along axis A. The base end is provided outside of barrel 100 in the upward direction, the bottom surface is connected to the rod-shaped portion, and a pressure measuring unit 141 is provided on the top surface.

[0019] The plunger 110 is hollow and inserted between the barrel 100 and the torpedo 120. Under heating by the heater 131, the plunger 110 pushes in the thermoplastic material 3 supplied from the supply device 30 to melt and plasticize the material. The plunger 110 is inserted into the barrel 100 so as to be movable back and forth along the axis A, and moves along the axis A in response to a force transmitted from the drive mechanism 150. The plunger 110 also has a hole penetrating from the top surface to the bottom surface, and the rod-shaped portion of the torpedo 120 is inserted into the hole so as to be movable along the axis A.

[0020] Heater 131 is a rod-shaped member provided inside torpedo 120, and heats torpedo 120 from the inside. Heater 131 starts and stops heating in accordance with a control command transmitted from control device 20.

[0021] The heater 132 is provided on the outer side surface of the barrel 100, and heats the barrel 100 from the outside. The heater 132 starts and stops heating in accordance with a control command transmitted from the control device 20.

[0022] The temperature measurement unit 144 is, for example, a thermometer having a thermocouple, and measures the temperature at a location where the thermocouple is connected. The temperature measurement unit 144 has a thermocouple provided inside the heater 131, and measures the temperature of the torpedo 120. The temperature measurement unit 144 transmits the measurement result to the control device 20. Note that the temperature measurement unit 144 may further include a separate unit for measuring the temperature of the barrel 100. The temperature measurement unit 144 for measuring the temperature of the barrel 100 measures the temperature of the barrel 100 using a thermocouple provided near the heater 132 on the barrel 100 or inside the heater 132. The temperature measurement unit 144 transmits the measurement result to the control device 20.

[0023] The pressure measuring unit 141 is, for example, a load sensor provided at the base end of the torpedo 120, and measures the pressure applied to the torpedo 120 in the direction of the axis A. The pressure measuring unit 141 also transmits the measurement result to the control device 20.

[0024] The position measurement unit 142 is, for example, a position detection device such as a scale, and measures the position of a predetermined point on the plunger 110 in the direction of the axis A. The position measurement unit 142 also transmits the measurement result to the control device 20. The predetermined point on the plunger 110 is, for example, the top surface of the base end of the plunger 110, or a corner formed by the top surface and side surface of the plunger 110.

[0025] The drive mechanism 150 is a mechanism that drives the torpedo 120 and the plunger 110 to independently move forward and backward in the direction of the axis A. The drive mechanism 150 drives the torpedo 120 and the plunger 110 in accordance with an operation control command from the control device 20.

[0026] The supply device 30 supplies the thermoplastic material 3 to a space 103 surrounded by the inner wall surface of the barrel 100 and the outer circumferential surface of the torpedo 120 in the injection device 10 under the control of the control device 20. Specifically, the supply device 30 supplies the thermoplastic material 3 stored in the supply device 30 or in an external container into the space 103 through the supply port 102 of the injection device 10 at a period indicated by a control command transmitted from the control device 20.

[0027] The control device 20 controls the pushing, melting, and injection operations of the thermoplastic material 3 by the injection device 10, and the supply operation of the thermoplastic material 3 to the injection device 10 by the supply device 30. The control device 20 also acquires various information related to the injection device 10 and the supply device 30 transmitted from the injection device 10 and the supply device 30. The control device 20 mainly includes a storage device 21 that stores various programs, various information, and information on processing results required for the CPU 22 to execute processing, and a CPU (Central Processing Unit) 22 that functions as various functional means by executing predetermined programs stored in the memory 24 or the storage device 21. The control device 20 also mainly includes a memory 24 that temporarily stores predetermined programs and data required for the CPU 22 to execute the predetermined programs, and a communication device 23 for communicating with external devices. The control device 20 also mainly includes an input / output device 25 that receives operations from the operator of the injection molding machine 1 and outputs screen displays, audio, and the like to the operator. The control device 20 can be realized using an information processing device such as a dedicated or general-purpose computer, and may be configured from a single information processing device or multiple information processing devices.

[0028] Next, a detailed description will be given of the configuration of the drive mechanism 150. Fig. 2 is a diagram showing the detailed configuration of the drive mechanism 150 shown in Fig. 1 together with the control device 20, the plunger 110, and the torpedo 120. As shown in Fig. 2, the main parts of the drive mechanism 150 include, for example, a hydraulic system 151, hydraulic cylinders 152A and 152B, and hydraulic pressure measurement units 143A and 143B.

[0029] The hydraulic system 151 is, for example, a hydraulic circuit, and drives the hydraulic cylinders 152A and 152B to operate the plunger 110 with a predetermined pressing force in accordance with a control signal CNT1 transmitted from the control device 20. The hydraulic system 151 has, for example, an electric motor (not shown) that rotates at a torque and rotational speed in accordance with the control signal CNT1. The hydraulic system 151 also has, for example, a hydraulic tank for storing oil, and a hydraulic pump (not shown) that discharges oil supplied from the hydraulic tank toward the hydraulic cylinders 152A and 152B in accordance with the rotation transmitted from the electric motor. The hydraulic system 151 also has, for example, flow paths (not shown) for supplying oil to the hydraulic cylinders 152A and 152B and for receiving oil flowing out from the hydraulic cylinders 152A and 152B. The hydraulic system 151 also has, for example, a directional valve for controlling the driving direction of the hydraulic cylinders 152A and 152B, a flow control valve for controlling the flow rate of oil in the flow path, and a hydraulic control valve for controlling the pressure of oil in the flow path (not shown).

[0030] The hydraulic cylinders 152A and 152B are, for example, double-acting hydraulic cylinders, and their rods and pistons move along the direction of axis A in accordance with the force and flow of oil flowing in and out of the hydraulic system 151. The hydraulic cylinder 152A transmits the force generated by the movement of the piston and rod to the plunger 110. The hydraulic cylinder 152A has a port on its cylinder cap side connected to the first flow path of the hydraulic system 151 and the hydraulic pressure measuring unit 143B, and a port on its rod side connected to the second flow path of the hydraulic system 151 and the hydraulic pressure measuring unit 143A. The hydraulic cylinder 152B transmits the force generated by the movement of the piston and rod to the torpedo 120. The hydraulic cylinder 152B has a port on its cylinder cap side connected to the third flow path of the hydraulic system 151, and a port on its rod side connected to the fourth flow path of the hydraulic system 151.

[0031] The hydraulic pressure measuring units 143A and 143B measure the hydraulic pressure of the oil flowing through the flow paths and transmit the measurement results to the control device 20. Specifically, the hydraulic pressure measuring unit 143A measures the hydraulic pressure of the oil flowing through the flow path between the rod-side port of the hydraulic cylinder 152A and the first flow path of the hydraulic system 151 and transmits a measurement signal M1 including the measurement results to the control device 20. In addition, the hydraulic pressure measuring unit 143B measures the hydraulic pressure of the oil flowing through the flow path between the cylinder cap-side port of the hydraulic cylinder 152A and the second flow path of the hydraulic system 151 and transmits a measurement signal M2 including the measurement results to the control device 20.

[0032] <Functional configuration> The overall configuration of the injection molding machine 1 and the configuration of the drive mechanism 150 have been described above in detail. Next, the functional configuration of the control device 20 in the injection molding machine 1 will be described. FIG. 3 is a diagram showing the functional configuration of the control device 20 shown in FIG. 1. As shown in FIG. 3, the control device 20 is configured such that its main functional components include, for example, an acquisition unit 210, a calculation unit 220, a drive unit 230, a heating unit 240, and a storage unit 250. Functional means other than the storage unit 250 are realized by the CPU 22 executing programs stored in the storage device 21 or the like.

[0033] The acquisition unit 210 acquires the measurement results measured by the injection device 10. The acquisition unit 210 refers to the storage unit 250 and updates the measurement data 253 with the acquired measurement results. Specifically, the acquisition unit 210 acquires the measurement results of the pressure applied to the torpedo 120 in the axial A direction from the pressure measurement unit 141. The acquisition unit 210 also acquires the measurement results of the position of a predetermined point on the plunger 110 in the axial A direction from the position measurement unit 142. The acquisition unit 210 also acquires the measurement results of the temperature of the torpedo 120 from the temperature measurement unit 144.

[0034] The acquisition unit 210 also acquires, from the hydraulic pressure measurement unit 143A, the measurement result of the hydraulic pressure of the oil flowing in the flow path between the rod-side port of the hydraulic cylinder 152A and the first flow path of the hydraulic system 151. The acquisition unit 210 also acquires, from the hydraulic pressure measurement unit 143B, the measurement result of the hydraulic pressure of the oil flowing in the flow path between the cylinder cap-side port of the hydraulic cylinder 152A and the second flow path of the hydraulic system 151.

[0035] The calculation unit 220 calculates the pressing force of the plunger 110 against the thermoplastic material 3 based on the measurement results of the injection device 10 acquired by the acquisition unit 210. In calculating the pressing force, the calculation unit 220 first calculates the filling rate of the thermoplastic material 3 in the barrel 100 based on the measurement results of the pressure applied to the torpedo 120 in the axial A direction and the measurement results of the position of a predetermined location on the plunger 110 in the axial A direction. Next, the calculation unit 220 calculates the pressing force of the plunger 110 based on the calculated filling rate, the measurement results of the temperature of the torpedo 120, and information indicating the type or size of the thermoplastic material 3 stored in the memory unit 250. The calculation unit 220 updates the setting value of the pressing force included in the setting data 252 stored in the memory unit 250 with the calculated value of the pressing force. Note that, in calculating the filling rate, the calculation unit 220 may use the amount of change over time in the position calculated from the measurement results of the position, instead of the measurement results of the position of the predetermined location on the plunger 110 in the axial A direction.

[0036] The drive unit 230 drives the injection device 10 and the supply device 30. Specifically, the drive unit 230 receives a control program stored in the storage unit 250 and instructions from the operator of the control device 20. The drive unit 230 also refers to setting data 252 stored in the storage unit 250. The drive unit 230 transmits a control signal CNT1 to the injection device 10 and a control signal CNT2 to the supply device 30, thereby driving the injection device 10 and the supply device 30 so that they operate in accordance with the setting values ​​included in the setting data 252.

[0037] Heating unit 240 controls the heating and stopping operations of heaters 131 and 132. Specifically, heating unit 240 refers to measurement data 253 and setting data 252 in memory unit 250, and controls the heating and stopping operations of heating unit 240 so that the measurement result of the temperature of torpedo 120 becomes the setting temperature included in setting data 252.

[0038] The storage unit 250 stores control programs for the injection device 10 and the supply device 30. The storage unit 250 also stores material information 251 indicating the type or size of the thermoplastic material 3, setting data 252 related to the operation of the injection device 10 and the supply device 30, and measurement data 253 including each measurement result related to the operation of the injection device 10. The storage unit 250 also stores various values ​​and information that the control device 20 needs to store in advance.

[0039] The material information 251 is information indicating the type, size, shape, etc. of the material of the thermoplastic material 3. For multiple types of thermoplastic material 3, the material information 251 includes a value previously associated with which material the material is made of, a value related to size such as radius or diameter, and a value previously associated with the shape. The type of shape is, for example, cylindrical, spherical, etc.

[0040] The setting data 252 is information indicating various setting values ​​used when driving the injection device 10 and the supply device 30. The setting data 252 includes, for example, the value of the pressing force of the plunger 110 and the cycle of one shot in which the injection device 10 presses, melts, and injects the thermoplastic material 3. The setting data 252 also includes the set oil pressure and set flow rate values ​​of the hydraulic cylinders 152A and 152B as values ​​related to the pressing force of the plunger 110. The setting data 252 also includes the amount of thermoplastic material 3 supplied by the supply device 30 and the set temperatures of the heaters 131 and 132.

[0041] The measurement data 253 is information indicating the measurement results measured by the injection device 10. The measurement data 253 includes the measurement results of each part by the injection device 10 acquired by the acquisition unit 210 described above, and the measurement time associated with each measurement result.

[0042] <Flow of operations> The above describes the functional configuration of the control device 20. Next, we will explain in detail the flow of a series of processes in the injection molding machine 1. Figure 4 is an example of a flowchart showing the flow of a series of processes in the injection molding machine 1 shown in Figure 1.

[0043] (Step SP10) The injection molding machine 1 executes the supplying process using the control device 20. In the supplying process, the injection molding machine 1 supplies one shot of thermoplastic material 3 indicated by the setting data 252 from the supply device 30 to the supply port 102 of the barrel 100. Here, with reference to FIG. 5A, the operation when the thermoplastic material 3 is supplied to the injection device 10 will be described. FIG. 5A is a diagram showing a partial cross section of the injection molding machine 1, illustrating the operation of the injection device 10 in the supplying process.

[0044] As shown in Fig. 5A, when the thermoplastic material 3 is supplied to the supply port 102 of the injection molding machine 1, a predetermined portion of the plunger 110 is positioned at position ref, which is a reference position, by driving the hydraulic cylinder 152A toward the rod side. Also, the tip of the torpedo 120 is positioned on the lower surface side by driving the hydraulic cylinder 152B toward the cylinder cap side. The supply device 30 supplies the thermoplastic material 3 to the space 103 of the barrel 100 through the supply port 102. Returning to Fig. 4, the process proceeds to step SP12.

[0045] (Step SP12) The injection molding machine 1 executes a plasticizing step and a calculation step using the control device 20. Specifically, the injection molding machine 1 first executes the plasticizing step. In the plasticizing step, the injection molding machine 1 drives the plunger 110 toward the injection port 104 so that the pressing force indicated by the setting data 252 is achieved, and pushes the thermoplastic material 3 toward the injection port 104. Here, with reference to FIG. 5B, the operation when the thermoplastic material 3 is pushed toward the injection port 104 by the plunger 110 will be described. FIG. 5B is a diagram showing a partial cross section of the injection molding machine 1, illustrating the operation of the plasticizing step of the injection device 10 shown in FIG.

[0046] As shown in FIG. 5B , when the thermoplastic material 3 is forced into the injection molding machine 1 by the plunger 110 and plasticized, the hydraulic cylinder 152A is driven toward the cylinder cap, so that the injection molding machine 1 is positioned, for example, a distance d away from the reference position ref. As a result, the thermoplastic material 3 in the barrel 100 is forced toward the injection port 104 by the plunger 110, passes through the gap between the gear-shaped portion at the tip of the torpedo 120 and the barrel 100, and moves toward the injection port 104. The thermoplastic material 3 melts as it passes through the gap between the torpedo 120, which is heated to a set temperature by heaters 131 and 132, and the barrel 100. Next, in the injection molding machine 1, the back pressure of the thermoplastic material 3 that has moved toward the injection port 104 drives the torpedo 120 upward (toward the opposite side of the injection port 104). As a result, in the injection molding machine 1, the hydraulic cylinder 152B moves toward the rod side as the torpedo 120 moves. Returning to FIG. 4, the process proceeds to step SP14.

[0047] (Step SP14) The injection molding machine 1 executes the calculation step following the plasticization step. In the calculation step, the injection molding machine 1 uses the pressure measurement unit 141 to measure the pressure applied in the axial A direction of the torpedo 120 when the plunger 110 is driven with the set pressing force. The direction of the pressure applied to the torpedo 120 is the direction of the upper surface in the axial A direction, because the plunger 110 pushes the thermoplastic material 3 toward the injection port 104. Then, the process proceeds to step SP16.

[0048] (Step SP16) In the calculation step, the injection molding machine 1 measures the position of a predetermined location on the plunger 110 in the direction of axis A using the position measurement unit 142. When measuring the position of the plunger 110, the injection molding machine 1 measures, for example, how much difference there is in either the up or down direction relative to a reference position ref, which is a reference position. Then, the processing proceeds to step SP16.

[0049] (Step SP18) In the calculation step, the injection molding machine 1 measures the temperature of the torpedo 120 using the temperature measurement unit 144. Then, the injection molding machine 1 acquires the results of measurements made by the pressure measurement unit 141, the position measurement unit 142, and the temperature measurement unit 144 using the acquisition unit 210 of the control device 20, and updates the measurement data 253 in the memory unit 250 with the acquired measurement results. Then, the process proceeds to step SP20.

[0050] (Step SP20) In a calculation step, the injection molding machine 1 uses the calculation unit 220 of the control device 20 to refer to the measurement data 253 and calculate the filling rate of the thermoplastic material 3 in the barrel 100 based on the measurement results of the pressure measurement unit 141 and the position measurement unit 142. The filling rate is, for example, the proportion of the volume of the thermoplastic material 3 in the space 103 that is closer to the injection port 104 than the plunger 110, and is expressed as a percentage. When calculating the filling rate, the injection molding machine 1 calculates the filling rate by, for example, referring to a correspondence table in which the filling rate is associated with a combination of information about the pressure applied to the torpedo 120, the position of the plunger 110, and the thermoplastic material 3. Furthermore, when calculating the filling rate, the injection molding machine 1 calculates the filling rate by, for example, substituting values ​​related to the pressure applied to the torpedo 120, the position of the plunger 110, and the thermoplastic material 3 into a filling rate derivation formula stored in the memory unit 250. Then, the process proceeds to step SP22.

[0051] (Step SP22) In the calculation step, the injection molding machine 1 uses the calculation unit 220 of the control device 20 to drive the plunger 110 based on the calculated filling rate and the measurement results of the temperature measurement unit 144 to calculate the pressing force when pressing the thermoplastic material 3. When calculating the pressing force, the injection molding machine 1 calculates the pressing force, for example, by referring to a correspondence table in which the pressing force is associated with a combination of the filling rate and the surface temperature of the torpedo 120. In addition, when calculating the pressing force, the injection molding machine 1 calculates the pressing force, for example, by substituting the filling rate and the surface temperature of the torpedo 120 into a pressing force derivation formula stored in the memory unit 250. Then, the processing proceeds to step SP24.

[0052] (Step SP24) In the calculation step, the injection molding machine 1 causes the calculation unit 220 of the control device 20 to refer to the storage unit 250, and updates the value of the pressing force in the setting data 252 with the value indicated by the pressing force of the plunger 110 calculated by the calculation unit 220. Then, the process proceeds to step SP26.

[0053] (Step SP26) The injection molding machine 1 executes the injection process under the control of the control device 20. Here, referring to FIG. 5C, the operation of the injection device 10 shown in FIG. 1 during the injection process is described. FIG. 5C is a cross-sectional view of a portion of the injection molding machine 1, illustrating the operation of the injection device 10 shown in FIG. 1 during the injection process. As shown in FIG. 5C, the injection molding machine 1 first moves the plunger 110 to a reference position ref by driving the hydraulic cylinder 152A toward the rod side. Next, the injection molding machine 1 moves the torpedo 120 downward along the axis A by driving the hydraulic cylinder 152B toward the cylinder cap side. As a result, the injection molding machine 1 injects the molten thermoplastic material 3 from the injection port 104 into a mold (not shown) provided outside the injection molding machine 1. Returning to FIG. 4, the process proceeds to step SP28.

[0054] (Step SP28) The injection molding machine 1 determines whether the timing for the next cycle of performing a series of processes including the supplying process, the plasticizing process, the calculating process, and the injecting process has arrived. The timing for performing the series of processes is stored, for example, in the storage unit 250 as data indicating the cycle of performing the series of processes or as a control program for the injection molding machine 1. If the determination is affirmative, the process returns to step SP10. On the other hand, if the determination is negative, the process proceeds to step SP30.

[0055] (Step SP30) The injection molding machine 1 determines, via the drive unit 230 of the control device 20, whether or not a stop command to stop a series of processes including the supplying process, the plasticizing process, the calculating process, and the injecting process has been transmitted from the operator of the control device 20, the control program, or the like. If the determination is negative, the process returns to step SP10. On the other hand, if the determination is positive, the series of processes shown in FIG. 4 ends.

[0056] <Effects> As described above, in this embodiment, the injection molding machine 1 updates the pressing force of the plunger 110 for each shot of the thermoplastic material 3. Therefore, the injection molding machine 1 can improve the stability of the quality of the thermoplastic material 3 after molding.

[0057] Furthermore, in this embodiment, the injection molding machine 1 updates the pressing force based on the pressure applied to the torpedo 120 during the pushing operation of the plunger 110. Therefore, the injection molding machine 1 can further improve the stability of the quality of the thermoplastic material 3 after molding.

[0058] Furthermore, in this embodiment, the injection molding machine 1 updates the pressing force depending on the position or the amount of change in the position of the plunger 110 over time during the pressing operation of the plunger 110. Therefore, the injection molding machine 1 can further improve the stability of the quality of the thermoplastic material 3 after molding.

[0059] Furthermore, in this embodiment, the injection molding machine 1 updates the pressing force depending on the temperature of the torpedo 120. Therefore, the injection molding machine 1 can further improve the stability of the quality of the thermoplastic material 3 after molding.

[0060] Furthermore, in this embodiment, the injection molding machine 1 calculates the filling rate of the thermoplastic material 3 in the barrel 100 from the pressure applied to the torpedo 120 and the position of the plunger 110, and calculates and updates the pressing force based on the calculated filling rate and information about the thermoplastic material 3. Therefore, the injection molding machine 1 can improve the stability of the quality of the thermoplastic material 3 after molding, taking into account the type, shape, size, etc. of the thermoplastic material 3.

[0061] <Modification> The present invention is not limited to the above-described embodiments. In other words, variations on the above-described embodiments, made by a person skilled in the art, are also included within the scope of the present invention as long as they incorporate the features of the present invention. Furthermore, the elements of the above-described embodiments and the modifications described below can be combined to the extent technically possible, and such combinations are also included within the scope of the present invention as long as they incorporate the features of the present invention. Alternatively, the execution or order of execution of each step in the flowchart may be changed as long as no technical contradictions arise.

[0062] For example, in the present embodiment, the injection molding machine 1 updates the pressing force of the plunger 110 for each shot of the thermoplastic material 3, but this is not limited to this. The injection molding machine 1 may also update the pressing force of the plunger 110, for example, after each of several shots. Furthermore, the injection molding machine 1 may refer to information regarding the cycle or timing of updating the pressing force from the storage unit 250, and update the pressing force of the plunger 110 at a timing according to the referenced information. With this configuration, the injection molding machine 1 updates the pressing force at an appropriate timing, not just for each shot, so that the thermoplastic material 3 can be molded with higher efficiency and the stability of the quality of the thermoplastic material 3 after molding can be improved.

[0063] Furthermore, after the processing of step SP24, the injection molding machine 1 may determine whether or not preparations for molding the thermoplastic material 3 are complete. If the determination is affirmative, the processing proceeds to the processing of step SP26. On the other hand, if the determination is negative, the processing returns to the processing of step SP10. With this configuration, the injection molding machine 1 can improve the stability of the quality of the molded thermoplastic material 3 even when repeatedly executing the steps including the supplying step, the plasticizing step, and the calculating step until preparations for molding the thermoplastic material 3 are complete.

[0064] Furthermore, when the injection molding machine 1 injects the thermoplastic material 3 from the injection port 104 in the processing of step SP26 in FIG. 4, the injection molding machine 1 may supply one shot of new thermoplastic material 3 from the supply device 30 to the supply port 102 of the barrel 100. That is, the injection molding machine 1 may perform the supply step in the next series of processing simultaneously with the injection step. In the subsequent processing, the injection molding machine 1 determines whether or not a stop command has been transmitted. If the determination is negative, the processing returns to the processing of step SP12. On the other hand, if the determination is positive, the processing ends. With this configuration, the injection molding machine 1 can improve the stability of the quality of the thermoplastic material 3 after molding, even when the injection step and the supply step are performed simultaneously.

[0065] In addition, in this embodiment, the injection molding machine 1 uses the position of the predetermined portion of the plunger 110 measured by the position measurement unit 142 when updating the pressing force of the plunger 110, but this is not limited to this. The injection molding machine 1 may, for example, calculate the difference between the position of the predetermined portion of the plunger 110 measured by the position measurement unit 142 and a reference position ref, which is a reference position. Furthermore, the injection molding machine 1 may store the calculated difference together with the measurement time in the memory unit 250. Furthermore, the injection molding machine 1 may calculate the amount of change per time in the difference between past positions of the predetermined portion of the plunger 110 and use the calculated amount of change to update the pressing force. With this configuration, the injection molding machine 1 uses the amount of change per time in the position of the predetermined portion of the plunger 110 when pressing, melting, and injecting the thermoplastic material 3 to update the pressing force, thereby further improving the stability of the quality of the thermoplastic material 3 after molding.

[0066] Furthermore, in this embodiment, the injection molding machine 1 uses a hydraulic circuit including hydraulic cylinders 152A and 152B as the drive mechanism 150 for driving the plunger 110 and the torpedo 120, but this is not limited to this. The drive mechanism 150 may be any mechanism that can drive the plunger 110 and the torpedo 120, such as a mechanism that directly drives the plunger 110 and the torpedo 120 using the power of an electric motor. With this configuration, the injection molding machine 1 can improve the stability of the quality of the thermoplastic material 3 after molding, even when the plunger 110 and the torpedo 120 are driven by a mechanism other than a hydraulically driven mechanism. [Explanation of symbols]

[0067] 1... injection molding machine, 3... thermoplastic material, 20... control device, 30... supply device, 100... barrel, 104... injection port, 110... plunger, 120... torpedo, 131... heater, 132... heater, 141... pressure measuring unit, 142... position measuring unit, 144... temperature measuring unit, 150... drive mechanism

Claims

1. an axially extending barrel into which a thermoplastic material is supplied; a torpedo extending in the axial direction and inserted into the barrel; a heater provided in at least one of the barrel and the torpedo; a supply device for supplying the thermoplastic material into a space surrounded by the inner wall surface of the barrel and the outer circumferential surface of the torpedo; a hollow plunger interposed between the barrel and the torpedo, for pushing and melting the thermoplastic material supplied from the supply device under heating by the heater; a drive mechanism that drives the torpedo and the plunger independently to move forward and backward in the axial direction; a control device that controls the operation of the drive mechanism so as to update the pressing force of the plunger for each shot or for each set of multiple shots that is a unit of injection operation; An injection molding machine comprising:

2. a pressure measuring unit provided at an end of the torpedo in the axial direction to measure a pressure applied to the torpedo; 2. The injection molding machine according to claim 1, wherein the control device updates the pressing force based on the pressure measured by the pressure measuring unit at least during the pressing operation of the plunger.

3. a position measuring unit for measuring the position of the plunger; 2. The injection molding machine according to claim 1, wherein the control device updates the pressing force based on at least the position or the amount of change in position over time measured by the position measurement unit during the pressing operation of the plunger.

4. Further provided is a temperature measuring unit for measuring the temperature of the barrel or the torpedo, The injection molding machine according to any one of claims 1 to 3, characterized in that the control device updates the pressing force based on the temperature measured by the temperature measuring unit at least during the pressing operation of the plunger.

5. a pressure measuring unit provided at an end of the torpedo in the axial direction and configured to measure a pressure applied to the torpedo, a position measuring unit configured to measure a position of the plunger, and a temperature measuring unit configured to measure a temperature of the torpedo; 2. The injection molding machine according to claim 1, wherein the control device calculates a filling rate of the thermoplastic material in the barrel based on the pressure measured by the pressure measuring unit and the position measured by the position measuring unit during the pushing operation of the plunger, and updates the pressing force based on the temperature measured by the temperature measuring unit during the pushing operation of the plunger, the filling rate, and information indicating a predetermined type or size of the thermoplastic material.

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