Injection molding machine, control method for injection molding machine

Abstract

This technology provides a way to reduce the power consumption of injection molding machines. [Solution] The injection molding machine 1 performs an injection molding process in which injection material is injected into molds 15 and 16 to manufacture molded products, and comprises a machine used for the injection molding process, a motor 32 that rotates the movable shaft 31A of the machine, a generator 33 that converts the rotational energy of the movable shaft 31A into electrical energy, and a power storage device 80 that stores the electrical energy obtained by the generator 33.

Description

Technical Field

[0005]

[0001] The present disclosure relates to an injection molding machine and a method for controlling the injection molding machine.

Background Art

[0002] An injection molding machine that performs an injection molding process for manufacturing a molded product by injecting an injection material into a mold is known. For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2023-156729) discloses an injection molding machine that executes each process such as a plasticizing process for plasticizing and metering an injection material supplied from a hopper and an injection process for injecting the plasticized and metered injection material into a mold by a mechanical operation using a motor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The injection molding machine disclosed in Japanese Patent Application Laid-Open No. 2023-156729 consumes power when operating a motor. If such power consumption can be reduced, it can lead to power saving and a reduction in carbon dioxide emissions.

[0005] The present disclosure has been made to solve such problems, and an object thereof is to provide a technology capable of reducing the power consumption of an injection molding machine.

Means for Solving the Problems

[0006] An injection molding machine according to an embodiment includes a machine used for an injection molding process, a motor that rotates a movable axis of the machine, a generator that converts rotational energy of the movable axis into electrical energy, and a power storage device that stores the electrical energy obtained by the generator.

[0007] A control method for an injection molding machine according to one embodiment includes the steps of: converting the rotational energy of the movable shaft of the machine, which is rotated by a motor, into electrical energy using a generator; storing the electrical energy obtained by the generator in a power storage device; and releasing the electrical energy stored in the power storage device. [Effects of the Invention]

[0008] According to this disclosure, the power consumption of injection molding machines can be reduced. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing an injection molding machine according to an embodiment. [Figure 2] This is a block diagram showing the internal configuration of the control system installed in an injection molding machine. [Figure 3] This is a timing chart showing the motor operation timing at each stage of the injection molding process. [Figure 4] This is a timing chart showing the motor speed changes and clutch operation timing during the mold closing process. [Figure 5] This is a timing chart showing the motor speed changes and clutch operation timing during the forward movement of the injection device. [Figure 6] This is a timing chart showing the motor speed changes and clutch operation timing during the injection process. [Figure 7] This is a timing chart showing the motor speed changes and clutch operation timing during the plasticization process. [Figure 8] This timing chart shows the motor speed change and clutch operation timing during the retraction of the injection unit. [Figure 9] This is a timing chart showing the motor speed changes and clutch operation timing during the mold opening process. [Figure 10]This timing chart shows the motor speed changes and clutch operation timing during the ejector advancement process. [Figure 11] This timing chart shows the motor speed changes and clutch operation timing during the ejector retraction process. [Figure 12] This flowchart shows an example of the process by which a control device controls a motor and a clutch. [Modes for carrying out the invention]

[0010] The embodiments of this disclosure will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated.

[0011] <Main components of an injection molding machine> The configuration of the injection molding machine 1 according to the embodiment will be described with reference to Figures 1 and 2. Figure 1 is a schematic diagram showing the injection molding machine 1 according to the embodiment.

[0012] As shown in Figure 1, the injection molding machine 1 comprises a bed 2, a clamping device 10, an injection device 20, and a control device 100. The clamping device 10 and the injection device 20 are located on the bed 2. The control device 100 may be located inside the bed 2 or outside the bed 2. The injection molding machine 1 is configured to manufacture molded products by injecting injection material from the injection device 20 into molds 15 and 16 attached to the clamping device 10. Mold 15 is an example of the “first mold portion” of this disclosure. Mold 16 is an example of the “second mold portion” of this disclosure. The injection material includes, for example, a plastic material referred to as pellets.

[0013] The mold clamping device 10 comprises a mold clamping housing 11, a mold clamping mechanism 12, a movable platen 13, a fixed platen 14, molds 15 and 16, an ejector 17, reduction gears 31 and 41, a motor 32, and a motor 42.

[0014] The movable platen 13 is disposed between the clamping housing 11 and the fixed platen 14. The clamping mechanism 12 is disposed between the clamping housing 11 and the movable platen 13 and includes a toggle mechanism that connects the clamping housing 11 and the movable platen 13. By expanding and contracting using the toggle mechanism, the clamping mechanism 12 brings the movable platen 13 closer to the clamping housing 11 fixed on the bed 2 and moves the movable platen 13 away from the fixed platen 14, or moves the movable platen 13 away from the clamping housing 11 and brings the movable platen 13 closer to the fixed platen 14.

[0015] The mold 15 is attached to the fixed platen 14. The mold 16 is attached to the movable platen 13. The mold 15 and the mold 16 are disposed opposite to each other between the fixed platen 14 and the movable platen 13. The mold 16 attached to the movable platen 13 approaches and adheres to the mold 15 or separates from the mold 15 as the movable platen 13 slides on the bed 2 due to the expansion and contraction operation of the clamping mechanism 12.

[0016] The ejector 17 projects the pin 18 toward the mold 16 or retracts the pin 18 from the mold 16. When the pin 18 projects into the mold 16, the molded product adhered to the mold 16 is removed.

[0017] The speed reduction device 31 is provided in the clamping mechanism 12 and is an example of the "machine" of the present disclosure. The speed reduction device 31 is composed of a belt and pulleys. The movable shaft 31A (input shaft) of the speed reduction device 31 is connected to the motor 32, and the output shaft of the speed reduction device 31 is connected to the toggle mechanism of the clamping mechanism 12. The motor 32 is, for example, a servo motor, and rotates the movable shaft 31A of the speed reduction device 31 according to the control of the control device 100. The speed reduction device 31 increases the torque of the motor 32 based on the rotational energy of the movable shaft 31A and rotates the output shaft. The clamping mechanism 12 expands and contracts using the rotation of the output shaft and slides the movable platen 13 on the bed 2.

[0018] As the movable platen 13 slides on the bed 2, the molds 15 and 16 come into close contact or separate. In this way, the injection molding machine 1 can bring the molds 15 and 16 into close contact or separate by rotating the movable shaft 31A of the reduction gear 31 with the motor 32.

[0019] A reduction gear 41 is provided on the ejector 17 and is an example of the “machine” of this disclosure. The reduction gear 41 consists of a belt and pulleys. The movable shaft 41A (input shaft) of the reduction gear 41 is connected to a motor 42, and the output shaft of the reduction gear 41 is connected to the ejector 17 via a ball screw (not shown). The motor 42 is, for example, a servo motor and rotates the movable shaft 41A of the reduction gear 41 according to the control of the control device 100. The reduction gear 41 increases the torque of the motor 42 based on the rotational energy of the movable shaft 41A, thereby rotating the output shaft. The ejector 17 uses the rotation of the output shaft to eject the pin 18 into the mold 16 or to retract the pin 18 from the mold 16.

[0020] The molded product is removed from the mold 16 by the pin 18 protruding from the mold 16. In this way, the injection molding machine 1 can remove the molded product formed by the injection material injected into the mold from the mold by rotating the movable shaft 41A of the reduction gear 41 with the motor 42.

[0021] The injection device 20 comprises a cylinder 21, a screw 22, a hopper 23, an injection nozzle 24, a nozzle touch device 25, a heater 26, reduction gears 51, 61, 71, a motor 52, a motor 62, and a motor 72.

[0022] The cylinder 21 has a cylindrical shape and is positioned on the nozzle touch device 25. The screw 22 is located inside the cylinder 21 and applies pressure to the injection material stored in the cylinder 21 to push it out, or rotates to knead the injection material. The hopper 23 is a container for storing a fixed amount of injection material that is supplied to the inside of the cylinder 21 in accordance with the drive of the screw 22. The injection nozzle 24 is located at the tip of the cylinder 21 and injects the injection material toward the molds 15, 16 mounted on the clamping device 10. The nozzle touch device 25 slides the entire injection device 20, including the cylinder 21, toward the clamping device 10. The heater 26 consists of multiple band heaters that cover the cylinder 21 and heat the cylinder 21.

[0023] A reduction gear 51 is provided on the nozzle touch device 25 and is an example of the “machine” of this disclosure. The reduction gear 51 consists of a belt and pulleys. The movable shaft 51A (input shaft) of the reduction gear 51 is connected to a motor 52, and the output shaft of the reduction gear 51 is connected to the nozzle touch device 25 via a ball screw (not shown). The motor 52 is, for example, a servo motor and rotates the movable shaft 51A of the reduction gear 51 according to the control of the control device 100. The reduction gear 51 increases the torque of the motor 52 based on the rotational energy of the movable shaft 51A, thereby rotating the output shaft. The nozzle touch device 25 uses the rotation of the output shaft to slide the injection device 20 toward the clamping device 10.

[0024] As the injection device 20 slides toward the clamping device 10, the distance between the cylinder 21 of the injection device 20 and the molds 15 and 16 of the clamping device 10 is changed. In this way, the injection molding machine 1 can change the distance between the cylinder 21 of the injection device 20 and the molds 15 and 16 of the clamping device 10 by rotating the movable shaft 51A of the reduction gear 51 with the motor 52.

[0025] A reduction gear 61 is provided on the screw 22 and is an example of the “machine” of this disclosure. The reduction gear 61 consists of a belt and pulleys. The movable shaft 61A (input shaft) of the reduction gear 61 is connected to a motor 62, and the output shaft of the reduction gear 61 is connected to the screw 22 via a ball screw (not shown). The motor 62 is, for example, a servo motor and rotates the movable shaft 61A of the reduction gear 61 according to the control of the control device 100. The reduction gear 61 increases the torque of the motor 62 based on the rotational energy of the movable shaft 61A, thereby rotating the output shaft. The screw 22 moves towards the injection nozzle 24 in the cylinder 21 using the rotation of the output shaft.

[0026] As the screw 22 moves towards the injection nozzle 24 within the cylinder 21, the injection material stored in the cylinder 21 is injected from the injection nozzle 24 into the molds 15 and 16. In this way, the injection molding machine 1 can inject the injection material stored in the cylinder 21 into the molds 15 and 16 by rotating the movable shaft 61A of the reduction gear 61 with the motor 62.

[0027] A reduction gear 71 is provided on the screw 22 and is an example of the “machine” of this disclosure. The reduction gear 71 consists of a belt and pulleys. The movable shaft 71A (input shaft) of the reduction gear 71 is connected to a motor 72, and the output shaft of the reduction gear 71 is connected to the screw 22. The motor 72 is, for example, a servo motor and rotates the movable shaft 71A of the reduction gear 71 according to the control of the control device 100. The reduction gear 71 increases the torque of the motor 72 based on the rotational energy of the movable shaft 71A, thereby rotating the output shaft. The screw 22 rotates within the cylinder 21 using the rotation of the output shaft.

[0028] As the screw 22 rotates within the cylinder 21, the injection material supplied from the hopper 23 is plasticized and metered within the cylinder 21. In this way, the injection molding machine 1 can knead the injection material within the cylinder 21 by rotating the movable shaft 71A of the reduction gear 71 with the motor 72.

[0029] Hereafter, motors 32, 42, 52, 62, and 72, or these together, will be referred to simply as "motors." Reducers 31, 41, 51, 61, and 71, or these together, will be referred to simply as "reducers." Movable shafts 31A, 41A, 51A, 61A, and 71A, or these together, will be referred to simply as "movable shafts."

[0030] Figure 2 is a block diagram showing the internal configuration of the control device 100 provided by the injection molding machine 1. As shown in Figure 2, the control device 100 comprises amplifiers 30, 40, 50, 60, and 70, and a control unit 110.

[0031] The amplifier 30 is connected to the control unit 110 and the motor 32, and supplies power to the motor 32 according to the control of the control unit 110. The motor 32 operates using the power from the amplifier 30 to rotate the movable shaft 31A of the reduction gear 31.

[0032] The amplifier 40 is connected to the control unit 110 and the motor 42, and supplies power to the motor 42 according to the control of the control unit 110. The motor 42 operates using the power from the amplifier 40 to rotate the movable shaft 41A of the reduction gear 41.

[0033] The amplifier 50 is connected to the control unit 110 and the motor 52, and supplies power to the motor 52 according to the control of the control unit 110. The motor 52 operates using the power from the amplifier 50 to rotate the movable shaft 51A of the reduction gear 51.

[0034] The amplifier 60 is connected to the control unit 110 and the motor 62, and supplies power to the motor 62 according to the control of the control unit 110. The motor 62 operates using the power from the amplifier 60 to rotate the movable shaft 61A of the reduction gear 61.

[0035] The amplifier 70 is connected to the control unit 110 and the motor 72, and supplies power to the motor 72 according to the control of the control unit 110. The motor 72 operates using the power from the amplifier 70 to rotate the movable shaft 71A of the reduction gear 71.

[0036] In the following, amplifiers 30, 40, 50, 60, and 70, or collectively referred to as "amplifiers," will be used.

[0037] The control unit 110 comprises an arithmetic unit 111, a memory 112, a storage device 113, and an interface 114.

[0038] The arithmetic unit 111 is a computing entity (computer) that performs injection molding processes related to injection molding. The arithmetic unit 111 is composed of processors such as a CPU (Central Processing Unit), MPU (Micro-Processing Unit), TPU (Tensor Processing Unit), or GPU (Graphics Processing Unit). While a processor, as an example of the arithmetic unit 111, has the function of performing predetermined processes by executing a predetermined program, some or all of these functions may be implemented using dedicated hardware circuits such as an ASIC (Application Specific Integrated Circuit) or FPGA (Field-Programmable Gate Array). The term "processor" is not limited to processors that execute processing using stored-program methods, such as CPUs, MPUs, TPUs, or GPUs, but may also include hardwired circuits such as ASICs or FPGAs. The arithmetic unit 111 is not limited to von Neumann type computers such as CPUs or GPUs, but may also consist of non-von Neumann type computers such as quantum computers or optical computers. The arithmetic unit 111 may be interpreted as a processing circuitry for controlling the clamping device 10 and the injection device 20. The arithmetic unit 111 may consist of one chip or multiple chips. Furthermore, the processor and associated processing circuitry may consist of multiple computers interconnected by wired or wireless connections via a local area network or wireless network. The processor and associated processing circuitry may also consist of a cloud computer that remotely performs calculations based on input data and outputs the calculation results to other devices located at a distance.

[0039] Memory 112 includes a storage area (for example, a working area) for storing program code or work memory when the arithmetic unit 111 executes various programs. Examples of memory 112 include volatile memory such as DRAM (Dynamic Random Access Memory) and SRAM (Static Random Access Memory), or non-volatile memory such as ROM (Read Only Memory) and flash memory. Memory 112 may also be interpreted as a processing circuitry that stores programs or data for controlling the clamping device 10 and the injection device 20.

[0040] The storage device 113 stores various programs or data executed by the arithmetic unit 111. For example, the storage device 113 stores a control program 115 executed by the arithmetic unit 111. The storage device 113 may be one or more non-transitory computer-readable media or one or more computer-readable storage media. Examples of storage devices 113 include HDDs (Hard Disk Drives) and SSDs (Solid State Drives). The storage device 113 may also be interpreted as a processing circuitry that stores programs or data for controlling the clamping device 10 and the injection device 20.

[0041] The control program 115 specifies the processing procedures for the control device 100 to control the clamping device 10 and the injection device 20.

[0042] Interface 114 is connected to each amplifier in a communicative manner. Interface 114 may also be interpreted as a processing circuitry for external communication.

[0043] <Injection molding process> The injection molding machine 1, configured as described above, is configured to manufacture molded products by performing an injection molding process through the operation of a motor. Figure 3 is a timing chart showing the motor operation timing at each stage of the injection molding process. As shown in Figure 3, the injection molding process includes stages such as mold closing, injection device advance, injection, plasticization, injection device retraction, mold opening, ejector advance, and ejector retraction. The injection molding machine 1 can manufacture one molded product by performing the injection molding process, which includes these multiple stages, once, and can manufacture multiple molded products by repeatedly performing the injection molding process.

[0044] The injection molding machine 1 performs the mold closing process from t0 to t1. During the mold closing process, the injection molding machine 1 supplies power to the motor 32 to rotate the movable shaft 31A of the reduction gear 31, extending the mold clamping mechanism 12. When the mold clamping mechanism 12 is extended, the movable platen 13 on which the mold 16 is mounted slides along the bed 2 and approaches the fixed platen 14 on which the mold 15 is mounted. As a result, the mold 15 and the mold 16 come into close contact.

[0045] The injection molding machine 1 performs the process of advancing the injection device from t1 to t2. During the injection device advancement, the injection molding machine 1 supplies power to the motor 52 to rotate the movable shaft 51A of the reduction gear 51, and the nozzle touch device 25 slides the injection device 20 toward the clamping device 10. As a result, the injection device 20 moves forward and approaches the clamping device 10, and the injection nozzle 24 of the cylinder 21 comes into contact with the mold 15 of the clamping device 10.

[0046] The injection molding machine 1 performs the injection process from t2 to t3. During the injection process, the injection molding machine 1 supplies power to the motor 62 to rotate the movable shaft 61A of the reduction gear 61, moving the screw 22 towards the injection nozzle 24 within the cylinder 21. As a result, the injection material stored in the cylinder 21 is injected from the injection nozzle 24 into the molds 15 and 16. The injection material injected into the molds 15 and 16 is held within the molds 15 and 16 under pressure, and the molds 15 and 16 form a molded product.

[0047] The injection molding machine 1 performs a plasticization process from t3 to t4. In the plasticization process, the injection molding machine 1 supplies a fixed amount of injection material stored in the hopper 23 into the cylinder 21. The injection molding machine 1 heats the cylinder 21 with a heater 26. Furthermore, the injection molding machine 1 supplies power to the motor 72 to rotate the movable shaft 71A of the reduction gear 71, thereby rotating the screw 22 inside the cylinder 21. This causes the injection material to be plasticized and measured inside the cylinder 21. Through this plasticization process, the injection material for manufacturing the next molded product is prepared.

[0048] The injection molding machine 1 performs the injection device retraction process from t4 to t5. During injection device retraction, the injection molding machine 1 supplies power to the motor 52 to rotate the movable shaft 51A of the reduction gear 51, and the nozzle touch device 25 slides the injection device 20 away from the clamping device 10. As a result, the injection device 20 retracts and moves away from the clamping device 10.

[0049] The injection molding machine 1 performs the mold opening process from t5 to t6. During the mold opening process, the injection molding machine 1 supplies power to the motor 32 to rotate the movable shaft 31A of the reduction gear 31, thereby retracting the mold clamping mechanism 12. When the mold clamping mechanism 12 is retracted, the movable platen 13 on which the mold 16 is mounted slides across the bed 2 and separates from the fixed platen 14 on which the mold 15 is mounted. As a result, the mold 15 and the mold 16 separate.

[0050] The injection molding machine 1 performs the ejection process from t6 to t8. The ejection process includes an ejector advance step and an ejector retraction step.

[0051] The injection molding machine 1 performs the ejector advancement process from t6 to t7. In the ejector advancement process, the injection molding machine 1 supplies power to the motor 42 to rotate the movable shaft 41A of the reduction gear 41, and the ejector 17 advances the pin 18 toward the mold 16. As a result, the pin 18 protrudes from the ejector 17 toward the mold 16.

[0052] The injection molding machine 1 performs the ejector retraction process from t7 to t8. In the ejector retraction process, the injection molding machine 1 supplies power to the motor 42 to rotate the movable shaft 41A of the reduction gear 41, and the ejector 17 retracts the pin 18 from the mold 16. Through this ejection process, the molded product that is in close contact with the mold 16 is removed from the mold 16 by the protrusion of the pin 18.

[0053] <Power generation processing> As described above, the injection molding machine 1 can perform injection molding using each motor, but it consumes electricity when operating each motor. If the injection molding machine 1 can reduce such power consumption, it can save electricity and reduce carbon dioxide emissions. Therefore, the injection molding machine 1 is configured to perform a power generation process that converts the rotational energy of each movable shaft connected to each motor into electrical energy, stores the obtained electrical energy, and reuses it.

[0054] Specifically, as shown in Figures 1 and 2, the injection molding machine 1 further comprises generators 33, 43, 53, 63, and 73, clutches 34, 44, 54, 64, and 74, and an energy storage device 80. Hereinafter, any one of the generators 33, 43, 53, 63, and 73, or all of them together, will be simply referred to as "generators." Any one of the clutches 34, 44, 54, 64, and 74, or all of them together, will be simply referred to as "clutches." As shown in Figure 2, the control unit 110 of the control device 100 is communicated with each clutch via an interface 114.

[0055] The clutch 34 is located between the generator 33 and the movable shaft 31A of the reduction gear 31. Specifically, one end of the movable shaft 31A is connected to the motor 32, while the other end of the movable shaft 31A is connected to the generator 33 via the clutch 34. The clutch 34 mechanically connects the generator 33 and the reduction gear 31, or mechanically disconnects them, according to the control of the control device 100.

[0056] The generator 33 is, for example, an alternator, and is configured to generate electricity by converting the rotational energy of the movable shaft 31A into electrical energy. The electrical energy obtained by the generator 33 is stored in the energy storage device 80.

[0057] The clutch 44 is located between the generator 43 and the movable shaft 41A of the reduction gear 41. Specifically, one end of the movable shaft 41A is connected to the motor 42, while the other end of the movable shaft 41A is connected to the generator 43 via the clutch 44. The clutch 44 mechanically connects the generator 43 and the reduction gear 41, or mechanically disconnects the generator 43 and the reduction gear 41, according to the control of the control device 100.

[0058] The generator 43 is, for example, an alternator, and is configured to generate electricity by converting the rotational energy of the movable shaft 41A into electrical energy. The electrical energy obtained by the generator 43 is stored in the energy storage device 80.

[0059] The clutch 54 is located between the generator 53 and the movable shaft 51A of the reduction gear 51. Specifically, one end of the movable shaft 51A is connected to the motor 52, while the other end of the movable shaft 51A is connected to the generator 53 via the clutch 54. The clutch 54 mechanically connects the generator 53 and the reduction gear 51, or mechanically disconnects the generator 53 and the reduction gear 51, according to the control of the control device 100.

[0060] The generator 53 is, for example, an alternator, and is configured to generate electricity by converting the rotational energy of the movable shaft 51A into electrical energy. The electrical energy obtained by the generator 53 is stored in the energy storage device 80.

[0061] The clutch 64 is located between the generator 63 and the movable shaft 61A of the reduction gear 61. Specifically, one end of the movable shaft 61A is connected to the motor 62, while the other end of the movable shaft 61A is connected to the generator 63 via the clutch 64. The clutch 64 mechanically connects the generator 63 and the reduction gear 61, or mechanically disconnects them, according to the control of the control device 100.

[0062] The generator 63 is, for example, an alternator, and is configured to generate electricity by converting the rotational energy of the movable shaft 61A into electrical energy. The electrical energy obtained by the generator 63 is stored in the energy storage device 80.

[0063] The clutch 74 is located between the generator 73 and the movable shaft 71A of the reduction gear 71. Specifically, one end of the movable shaft 71A is connected to the motor 72, while the other end of the movable shaft 71A is connected to the generator 73 via the clutch 74. The clutch 74 mechanically connects the generator 73 and the reduction gear 71, or mechanically disconnects them, according to the control of the control device 100.

[0064] The generator 73 is, for example, an alternator, and is configured to generate electricity by converting the rotational energy of the movable shaft 71A into electrical energy. The electrical energy obtained by the generator 73 is stored in the energy storage device 80.

[0065] Hereinafter, the clutch state when the generator and the reduction gear are mechanically connected will be referred to as the "on state," and the clutch state when the generator and the reduction gear are mechanically disconnected will be referred to as the "off state." The clutch off state is an example of the "first state" of this disclosure. The clutch on state is an example of the "second state" of this disclosure. When the clutch is on, the rotational energy of the movable shaft of the reduction gear is transmitted to the generator. When the clutch is off, the rotational energy of the movable shaft of the reduction gear is not transmitted to the generator. The clutch off state is an example of the "first state" of this disclosure. The clutch on state is an example of the "second state" of this disclosure.

[0066] The energy storage device 80 is connected to each generator and collects and stores the power (electrical energy) obtained by each generator, and releases the stored power according to the control of the control device 100. The control device 100 is connected to the energy storage device 80 and uses the power stored in the energy storage device 80 to supply power for operation from each amplifier to each motor.

[0067] In this way, the injection molding machine 1 can generate electricity by converting the rotational energy of the movable shaft operating in each step of the injection molding process into electrical energy using a generator connected to the movable shaft of the reduction gear. For example, when a motor decelerates from a high speed, the movable shaft of the reduction gear rotates by inertia. By converting the rotational energy due to the inertial rotation of the movable shaft into electrical energy, the injection molding machine 1 can reuse rotational energy that would otherwise be consumed as heat energy. As a result, the injection molding machine 1 can reduce power consumption and save electricity, and reduce carbon dioxide emissions.

[0068] Here, the injection molding machine 1 may connect the generator directly to the movable shaft of the reduction gear without using a clutch. In this case, the generator can always convert the rotational energy of the movable shaft into electrical energy and generate power while the movable shaft of the reduction gear rotates due to the operation of the motor. However, the injection molding machine 1 must operate each mechanical component such as the clamping mechanism 12, ejector 17, screw 22, or nozzle touch device 25 in each step of the injection molding process to produce a molded product, and there are periods when the motor is subjected to an excessive load. If the generator is connected to the movable shaft of the reduction gear during such a period when the motor is subjected to an excessive load, the load on the motor when it rotates the movable shaft will increase, and the power consumption of the motor may also increase. In other words, the power generated by the generator and the power consumption of the motor may cancel each other out, resulting in no power saving.

[0069] Therefore, the control device 100 of the injection molding machine 1, in each step of the injection molding process, turns the clutch off during periods when the motor is subjected to an excessive load to prevent the rotational energy of the movable shaft from being transmitted to the generator, and turns the clutch on during periods when the motor is not subjected to an excessive load to allow the rotational energy of the movable shaft to be transmitted to the generator.

[0070] Specifically, the control device 100 determines whether the load on the motor is above a threshold. If the load on the motor is above the threshold, the control device 100 controls the clutch to the off state, and if the load on the motor is below the threshold, it controls the clutch to the on state.

[0071] The threshold value used for determination described above may be a current value preset by the designer of the injection molding machine 1. For example, the control device 100 may monitor the current flowing through the motor and control the clutch to the off state when the current flowing through the motor is greater than or equal to the threshold value, and control the clutch to the on state when the current flowing through the motor is less than the threshold value.

[0072] Alternatively, the threshold value for determination may be a torque value preset by the designer of the injection molding machine 1. For example, the control device 100 may calculate the load torque from the current flowing through the motor, control the clutch to the off state if the load torque applied to the motor is greater than or equal to the threshold value, and control the clutch to the on state if the load torque applied to the motor is less than the threshold value.

[0073] <Timing of power generation process> Referring to Figures 4 to 11, an example of the timing of the power generation process executed by the control device 100 in each step of the injection molding process will be explained.

[0074] Figure 4 is a timing chart showing the speed change of the motor 32 and the operating timing of the clutch 34 during the mold closing process. As shown in Figure 4, when the motor 32 starts operating from a stationary state at t10, the motor 32 reaches a high speed state at t11. As the motor 32 operates at high speed from t11 to t12, the mold 15 mounted on the fixed platen 14 and the mold 16 mounted on the movable platen 13 move closer together. As the molds 15 and 16 move closer together, the motor 32 decelerates from t12 to t13, and the molds 15 and 16 come into close contact. Once the molds 15 and 16 are in close contact, the mold clamping is performed from t13 to t14.

[0075] In the mold closing process shown in Figure 4, the current flowing to the motor 32 exceeds a threshold value during the period from t10 to t11 when the motor 32 moves from a stationary state to an operational state, from t11 to t12 when the motor 32 operates at high speed, and from t13 to t14 when mold clamping is performed, increasing the load on the motor 32. During these periods, the control device 100 controls the clutch 34 to the off state to prevent the rotational energy of the movable shaft 31A from being transmitted to the generator 33. On the other hand, during the period from t12 to t13 when the motor 32 is decelerating and rotating by inertia, the current flowing to the motor 32 falls below the threshold value. During these periods, the control device 100 controls the clutch 34 to the on state so that the rotational energy of the movable shaft 31A is transmitted to the generator 33, thereby generating electricity.

[0076] Figure 5 is a timing chart showing the speed change of the motor 52 and the operating timing of the clutch 54 during the forward movement of the injection device. As shown in Figure 5, when the motor 52 starts operating from a stationary state at t20, the motor 52 reaches a high speed state at t21. As the motor 52 operates at high speed from t21 to t22, the injection device 20 moves forward and approaches the clamping device 10. As the injection device 20 approaches the clamping device 10, the motor 52 decelerates from t22 to t23. When the motor 52 stops from t23 to t24, the injection device 20 stops.

[0077] In the forward movement of the injection device shown in Figure 5, the current flowing to the motor 52 exceeds a threshold value during the period from t20 to t21 when the motor 52 moves from a stationary state to an operational state, and during the period from t21 to t22 when the motor 52 is operating at high speed, increasing the load on the motor 52. Also, the movable shaft 51A stops during the period from t23 to t24 when the motor 52 stops. During these periods, the control device 100 controls the clutch 54 to the off state so that the rotational energy of the movable shaft 51A is not transmitted to the generator 53. On the other hand, during the period from t22 to t23 when the motor 52 is decelerating and rotating by inertia, the current flowing to the motor 52 falls below a threshold value. During these periods, the control device 100 controls the clutch 54 to the on state so that the rotational energy of the movable shaft 51A is transmitted to the generator 53, thereby generating electricity.

[0078] Figure 6 is a timing chart showing the speed changes of the motor 62 and the operating timing of the clutch 64 during the injection process. As shown in Figure 6, when the motor 62 starts operating from a stationary state at t30, the motor 62 reaches a high-speed, low-load state at t31. From t31 to t32, the injection material is injected from the injection nozzle 24 into the molds 15 and 16, during which time the motor 62 operates at high speed and low load. From t32 to t33, the motor 62 operates at a constant speed, causing the injection nozzle 24 to move to the holding pressure position. Holding pressure is performed from t33 to t34.

[0079] In the injection process shown in Figure 6, the current flowing to the motor 62 exceeds a threshold value during the period from t30 to t31 when the motor 62 moves from a stationary state to an operating state, from t32 to t33 when the injection nozzle 24 moves to the holding pressure position, and from t33 to t34 when the holding pressure is performed, increasing the load on the motor 62. During these periods, the control device 100 controls the clutch 64 to the off state to prevent the rotational energy of the movable shaft 61A from being transmitted to the generator 63. On the other hand, during the period from t31 to t32 when the motor 62 is in a high-speed, low-load state, the current flowing to the motor 62 falls below a threshold value. During these periods, the control device 100 controls the clutch 64 to the on state so that the rotational energy of the movable shaft 61A is transmitted to the generator 63, thereby generating electricity.

[0080] Figure 7 is a timing chart showing the speed change of the motor 72 and the operating timing of the clutch 74 during the plasticization process. As shown in Figure 7, the motor 72 starts operating from a stationary state at t40, and reaches a high speed state at t41. From t41 to t42, the motor 72 operates at high speed, causing the screw 22 to rotate in the cylinder 21 and the injection material to be mixed. From t42 to t43, the motor 72 decelerates, and then the motor 72 stops, and the rotation of the screw 22 stops.

[0081] In the plasticization process shown in Figure 7, the current flowing to the motor 72 exceeds a threshold value during the period from t40 to t41 when the motor 72 moves from a stationary state to an operational state, and during the period from t41 to t42 when the motor 72 is operating at high speed, increasing the load on the motor 72. During these periods, the control device 100 controls the clutch 74 to the off state to prevent the rotational energy of the movable shaft 71A from being transmitted to the generator 73. On the other hand, during the period from t42 to t43 when the motor 72 is decelerating and rotating by inertia, the current flowing to the motor 72 falls below a threshold value. During these periods, the control device 100 controls the clutch 74 to the on state so that the rotational energy of the movable shaft 71A is transmitted to the generator 73, thereby generating electricity.

[0082] Figure 8 is a timing chart showing the speed change of the motor 52 and the operating timing of the clutch 54 during the retraction of the injection device. As shown in Figure 8, when the motor 52 starts operating from a stationary state at t50, the motor 52 reaches a high speed state at t51. As the motor 52 operates at high speed from t51 to t52, the injection device 20 retracts and moves away from the clamping device 10. Once the injection device 20 moves away from the clamping device 10, the motor 52 decelerates from t52 to t53, and then the motor 52 stops, causing the injection device 20 to stop.

[0083] In the retraction of the injection device shown in Figure 8, the current flowing to the motor 52 exceeds a threshold value during the period from t50 to t51 when the motor 52 moves from a stationary state to an operational state, and during the period from t51 to t52 when the motor 52 is operating at high speed, increasing the load on the motor 52. During this period, the control device 100 controls the clutch 54 to the off state to prevent the rotational energy of the movable shaft 51A from being transmitted to the generator 53. On the other hand, during the period from t52 to t53 when the motor 52 is decelerating and rotating by inertia, the current flowing to the motor 52 falls below a threshold value. During this period, the control device 100 controls the clutch 54 to the on state so that the rotational energy of the movable shaft 51A is transmitted to the generator 53, thereby generating electricity.

[0084] Figure 9 is a timing chart showing the speed change of the motor 32 and the operating timing of the clutch 34 during the mold opening process. As shown in Figure 9, mold relaxation occurs as the motor 32 operates from t60 to t61. At t61, the motor 32 transitions to a high-speed state, and at t62, the motor 32 reaches a high-speed state. From t62 to t63, the motor 32 operates at high speed, causing the movable platen 13 to move away from the fixed platen 14. As the movable platen 13 moves away from the fixed platen 14, the motor 32 decelerates from t63 to t64, causing the mold 15 and mold 16 to separate.

[0085] In the mold opening process shown in Figure 9, during the period from t60 to t62 when the motor 32 enters operation mode and transitions to high speed mode, and during the period from t62 to t63 when the motor 32 is operating at high speed, the current flowing to the motor 32 exceeds a threshold, and the load on the motor 32 increases. During this period, the control device 100 controls the clutch 34 to the off state so that the rotational energy of the movable shaft 31A is not transmitted to the generator 33. On the other hand, during the period from t63 to t64 when the motor 32 is decelerating and rotating by inertia, the current flowing to the motor 32 falls below the threshold. During this period, the control device 100 controls the clutch 34 to the on state so that the rotational energy of the movable shaft 31A is transmitted to the generator 33, thereby generating electricity.

[0086] Figure 10 is a timing chart showing the speed change of the motor 42 and the operating timing of the clutch 44 during the ejector advancement process. As shown in Figure 10, when the motor 42 starts operating from a stationary state at t70, the motor 42 reaches a high speed state at t71. As the motor 42 operates at high speed from t71 to t72, the ejector 17 moves the pin 18 forward and approaches the mold 16. As the pin 18 approaches the mold 16, the motor 42 decelerates from t72 to t73.

[0087] In the ejector advancement process shown in Figure 10, the current flowing to the motor 42 exceeds a threshold value during the period from t70 to t71 when the motor 42 moves from a stationary state to an operational state, and during the period from t71 to t72 when the motor 42 is operating at high speed, increasing the load on the motor 42. During these periods, the control device 100 controls the clutch 44 to the off state to prevent the rotational energy of the movable shaft 41A from being transmitted to the generator 43. On the other hand, during the period from t72 to t73 when the motor 42 is decelerating and rotating by inertia, the current flowing to the motor 42 falls below a threshold value. During these periods, the control device 100 controls the clutch 44 to the on state so that the rotational energy of the movable shaft 41A is transmitted to the generator 43, thereby generating electricity.

[0088] Figure 11 is a timing chart showing the speed change of the motor 42 and the operating timing of the clutch 44 during the ejector retraction process. As shown in Figure 11, when the motor 42 starts operating from a stationary state at t80, the motor 42 reaches a high speed state at t81. As the motor 42 operates at high speed from t81 to t82, the ejector 17 retracts the pin 18 and moves it away from the mold 16. As the pin 18 moves away from the mold 16, the motor 42 decelerates from t82 to t83.

[0089] In the ejector retraction process shown in Figure 11, the current flowing to the motor 42 exceeds a threshold value during the period from t80 to t81 when the motor 42 moves from a stationary state to an operational state, and during the period from t81 to t82 when the motor 42 is operating at high speed, increasing the load on the motor 42. During these periods, the control device 100 controls the clutch 44 to the off state to prevent the rotational energy of the movable shaft 41A from being transmitted to the generator 43. On the other hand, during the period from t82 to t83 when the motor 42 is decelerating and rotating by inertia, the current flowing to the motor 42 falls below a threshold value. During these periods, the control device 100 controls the clutch 44 to the on state so that the rotational energy of the movable shaft 41A is transmitted to the generator 43, thereby generating electricity.

[0090] In this way, the injection molding machine 1 controls the clutch to turn on or off based on the load on the motor (specifically, the current flowing through the motor) at each stage of the injection molding process, thereby switching between generating power and not generating power, and generating power at an appropriate timing that takes into account the load on the motor.

[0091] <Flowchart of power generation process> An example of the power generation process performed by the injection molding machine 1 will be explained with reference to Figure 12. Figure 12 is a flowchart showing an example of the process by which the control device 100 controls the motor and clutch. Each step of the power generation process shown in Figure 12 is realized by the arithmetic unit 111 of the control device 100 executing the control program 115. The control device 100 repeatedly executes the power generation process shown in Figure 12 in each step of the injection molding process to control the motor and clutch used in each step. Threshold values ​​are predetermined by the designer for each step and stored in the memory device 113.

[0092] As shown in Figure 12, the control device 100 determines whether the load on the motor is below a threshold (S1). For example, the control device 100 determines whether the current flowing through the motor is below a threshold.

[0093] If the load on the motor exceeds a threshold (NO in S1), the control device 100 controls the clutch to the off state to prevent the rotational energy of the movable shaft from being transmitted to the generator (S2), and repeats the process of this flowchart from S1.

[0094] Meanwhile, if the load on the motor is below a threshold (YES in S1), the control device 100 controls the clutch to the ON state so that the rotational energy of the movable shaft is transmitted to the generator, thereby generating electricity (S3). The control device 100 stores the electrical energy obtained by the generation in the energy storage device 80 (S4), and the process of this flowchart is repeated from S1. The electrical energy stored in the energy storage device 80 in this way is released to the motor by the control device 100 and used to operate the motor.

[0095] In this way, the injection molding machine 1 controls the clutch to the off state when the load on the motor increases during each step of the injection molding process, i.e., when the current flowing to the motor exceeds a threshold, thereby preventing the rotational energy of the movable shaft from being transmitted to the generator. On the other hand, when the load on the motor decreases, i.e., when the current flowing to the motor falls below a threshold, the clutch is controlled to the on state, allowing the rotational energy of the movable shaft to be transmitted to the generator and generate electricity. As a result, the injection molding machine 1 can convert the wasted rotational energy of the movable shaft, which would otherwise be consumed as thermal energy, into electrical energy and reuse it. This allows the injection molding machine 1 to reduce power consumption, conserve energy, and reduce carbon dioxide emissions.

[0096] Furthermore, the injection molding machine 1 does not connect the generator to the movable shaft of the reduction gear during periods when the motor is under excessive load. This avoids generating electricity while the load increases as the motor rotates the movable shaft, thus enabling efficient energy saving.

[0097] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended. [Explanation of Symbols]

[0098] 1 Injection molding machine, 2 Bed, 10 Clamping device, 11 Clamping housing, 12 Clamping mechanism, 13 Movable platen, 14 Fixed platen, 15,16 Mold, 17 Ejector, 18 Pin, 20 Injection device, 21 Cylinder, 22 Screw, 23 Hopper, 24 Injection nozzle, 25 Nozzle touch device, 26 Heater, 30,40,50,60,70 Amplifier, 31,41,51,61,71 Reduction gear, 31A,41A,51A,61A,71A Movable shaft, 32,42,52,62,72 Motor, 33,43,53,63,73 Generator, 34,44,54,64,74 Clutch, 80 Energy storage device, 100 Control device, 110 Control unit, 111 Calculation unit, 112 Memory, 113 storage device, 114 interface, 115 control program.

Claims

1. An injection molding machine that performs an injection molding process to manufacture a molded product by injecting injection material into a mold, The machine used in the injection molding process, A motor that rotates the movable shaft of the aforementioned machine, A generator that converts the rotational energy of the aforementioned movable shaft into electrical energy, An injection molding machine comprising a power storage device for storing electrical energy obtained by the aforementioned generator.

2. A clutch is further provided between the generator and the movable shaft. The injection molding machine according to claim 1, wherein the clutch switches the connection state between the generator and the movable shaft between a first state in which the rotational energy of the movable shaft is not transmitted to the generator and a second state in which the rotational energy of the movable shaft is transmitted to the generator.

3. The device further comprises a control device for controlling the clutch, The control device is When the load on the motor exceeds a threshold, the clutch is controlled to change the connection state to the first state. The injection molding machine according to claim 2, wherein when the load on the motor is less than the threshold, the clutch is controlled to change the connection state to the second state.

4. The injection molding machine according to claim 3, wherein the control device determines whether the load on the motor is greater than or equal to the threshold value based on the current flowing through the motor.

5. The mold is composed of a first mold portion and a second mold portion, The injection molding machine according to any one of claims 1 to 4, wherein the machine includes a configuration for bringing the first mold portion and the second mold portion into close contact or separating them.

6. The injection molding machine according to any one of claims 1 to 4, wherein the machine includes a configuration for changing the distance between a cylinder for storing the injection material and the mold.

7. The injection molding machine according to any one of claims 1 to 4, wherein the machine includes a configuration for injecting the injection material stored in a cylinder into the mold.

8. The injection molding machine according to any one of claims 1 to 3, wherein the machine includes a configuration for plasticizing and measuring the injection material.

9. The injection molding machine according to any one of claims 1 to 4, wherein the machine includes a configuration for removing the injection material injected into the mold from the mold.

10. A control method for an injection molding machine that performs an injection molding process to manufacture a molded product by injecting injection material into a mold, further including the following steps: The injection molding machine is, The machine used in the injection molding process, A motor that rotates the movable shaft of the aforementioned machine, A generator connected to the aforementioned movable shaft, Equipped with an energy storage device, (a) The step of converting the rotational energy of the movable shaft into electrical energy using the generator; (b) A step of storing the electrical energy obtained by the generator in the energy storage device; (c) A step of releasing the electrical energy stored in the energy storage device.

11. The control method according to claim 10, further comprising the following steps: The injection molding machine further includes a clutch between the generator and the movable shaft, (d) A step of controlling the clutch to switch the connection state between the generator and the movable shaft between a first state in which the rotational energy of the movable shaft is not transmitted to the generator and a second state in which the rotational energy of the movable shaft is transmitted to the generator.

12. The control method according to claim 11, further comprising the following steps in step (d): (e) When the load on the motor is greater than or equal to a threshold, the clutch is controlled to change the connection state to the first state; (f) A step of controlling the clutch to change the connection state to the second state when the load on the motor is less than the threshold.

13. The control method according to claim 12, further comprising the following steps in step (d): (g) A step of determining whether the load on the motor is greater than or equal to the threshold value, based on the current flowing through the motor.

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