Injection molding machine

Abstract

To suppress unintentional changes in a rotation angle of a motor due to external forces on the motor while at the same time suppressing an increase in power consumption.SOLUTION: An injection molding machine includes a servo motor 80A, a servo amplifier 50A, and a control device 40. The servo amplifier 50A includes a first switching element U1 and a second switching element V1. A molding cycle includes a first period in which the servo motor 80A is rotated and a second period in which it is not rotated. The servo motor 80A is configured to be able to perform motor rotation control, servo-off control, and zero speed control. The control device 40 executes motor rotation control in the first period, and executes servo-off control or zero speed control in the second period.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] This disclosure relates to an injection molding machine.

Background Art

[0002] In a factory, an injection molding machine is used to mold molded products based on plastic resins and the like. Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2020-069756) describes an electric injection molding machine having a servo motor. Such an injection molding machine repeatedly executes a molding cycle of an injection molding process including a plurality of processes such as an injection process and a holding pressure process to mass-produce molded products.

[0003] The injection molding machine of Patent Document 1 is equipped with a motor for executing a molding cycle. Patent Document 1 discloses a circuit diagram of a power supply system for supplying power to the motor. The power supply system of Patent Document 1 includes a PWM converter to which a three-phase AC voltage line is connected, a DC voltage line inside the molding machine connected to the output side of the PWM converter, and an inverter connected to the DC voltage line. The inverter generates a three-phase AC voltage to drive the motor.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The molding cycle includes a period during which the motor is rotating and a period during which the motor is stopped. During the period when the motor is stopped, control may be performed to stop the motor's rotation angle at a predetermined angle by turning on at least one of the inverter's switching elements. When the motor is stopped by turning on at least one of the inverter's switching elements, unintended changes in the motor's rotation angle due to external forces can be suppressed, but power consumption is generated by the switching of the switching element.

[0006] This disclosure was made to solve these problems, and its purpose is to suppress an increase in power consumption while preventing the motor's rotation angle from changing unintentionally due to external forces being generated in the motor. [Means for solving the problem]

[0007] An injection molding machine according to one embodiment includes a first servo motor, a first servo amplifier that supplies power to the first servo motor, and a control device that controls the first servo amplifier to execute a molding cycle. The first servo amplifier includes a first switching element and a second switching element. The molding cycle includes a first period in which the first servo motor is rotated and a second period in which the first servo motor is not rotated. The first servo motor is configured to rotate when controlled by a first control and to stop when controlled by a second control or a third control. The first control is a control that rotates the first servo motor by controlling the first switching element and the second switching element to be turned on in different phases. 3 The control involves turning on the first switching element and the second switching element in the same phase, thereby stopping the rotation of the first servo motor. 2 The control involves turning off the first switching element and the second switching element to stop the rotation of the first servo motor. The control device performs the first control during the first period and the second or third control during the second period. [Effects of the Invention]

[0008] The injection molding machine described herein aims to suppress an increase in power consumption while preventing the motor's rotation angle from changing unintentionally due to external forces generated in the motor. [Brief explanation of the drawing]

[0009] [Figure 1] This is an external view of the injection molding machine in Embodiment 1. [Figure 2] This is a schematic block diagram of the injection molding machine in Embodiment 1. [Figure 3] This diagram shows the details of the electrical circuit configuration of the servo amplifier in Embodiment 1. [Figure 4] This is a diagram illustrating the operation of a switching element. [Figure 5] This is a diagram illustrating the molding cycle in Embodiment 1. [Figure 6] This is a schematic block diagram of the injection molding machine in Embodiment 2. [Figure 7] This flowchart shows the processing procedure for determining the zero-speed period and the servo-off period. [Figure 8] This is a diagram illustrating the test cycle in Embodiment 2. [Figure 9] This is a schematic block diagram of the injection molding machine in Embodiment 3. [Figure 10] This flowchart shows the procedure for switching between zero-speed control and servo-off control in Embodiment 3. [Figure 11] This flowchart shows the procedure for switching between zero-speed control and servo-off control in modified example 1. [Figure 12] This is a flowchart showing the processing procedure for injection molding in modified example 2. [Modes for carrying out the invention]

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated. [Embodiment 1] <Configuration of Injection Molding Machine> Hereinafter, the injection molding machine 100 in Embodiment 1 will be described with reference to FIG. 1. FIG. 1 is an external view of the injection molding machine 100 in Embodiment 1.

[0011] The injection molding machine 100 is placed on the XY plane. The direction perpendicular to the XY plane is the Z-axis direction. Hereinafter, in FIG. 1, the positive direction of the Z-axis may be referred to as the upper surface side or the upper side, and the negative direction may be referred to as the lower surface side or the lower side. Although the injection molding machine 100 shown in FIG. 1 is shown as a horizontal injection molding machine, the injection molding machine 100 of Embodiment 1 is not limited to horizontal type and may be a vertical injection molding machine.

[0012] The injection molding process executed by the injection molding machine 100 includes a mold closing process, an injection process, a holding pressure process, a mold opening process, a cooling process, a protruding process, and a plasticizing process. The injection molding machine 100 repeatedly executes the above injection molding process cycle. Hereinafter, one unit cycle for molding one molded product is referred to as a "molding cycle". The injection molding machine 100 can mold molded products of various shapes and materials, and performs an injection molding process according to the shape and material type of the molded product.

[0013] The injection molding machine 100 includes a mold clamping device 10 for clamping the mold, an injection device 20 for melting and injecting an injection material, an operation panel 30, and control devices 40A to 40D. The mold clamping device 10 is arranged on the negative direction side of the X-axis with respect to the injection device 20.

[0014] <Mold Clamping Device> In Embodiment 1, the mold clamping device 10 includes a bed 11, a fixed platen 12, a mold clamping housing 13, a movable platen 14, tie bars 15, a mold clamping mechanism 16, molds 17, 18, a ball screw 19, and servo motors 80C, 80D. The bed 11 holds the fixed platen 12, the mold clamping housing 13, the movable platen 14, etc. The fixed platen 12 is fixed to the bed 11. Each of the mold clamping housing 13 and the movable platen 14 is configured to be slidable in the X-axis direction on the bed 11.

[0015] The tie bars 15 are disposed between the fixed platen 12 and the mold clamping housing 13 and connect the fixed platen 12 and the mold clamping housing 13. The tie bars 15 shown in FIG. 1 include four bars. Note that the number of bars included in the tie bars 15 is not limited to four and may be, for example, five or more.

[0016] The movable platen 14 is configured to be slidable in the X-axis direction between the fixed platen 12 and the mold clamping housing 13. The mold clamping mechanism 16 is provided between the mold clamping housing 13 and the movable platen 14. The mold clamping housing 13 in Embodiment 1 is configured to include a toggle mechanism. Note that the mold clamping mechanism 16 may be configured to include a direct pressure type mold clamping mechanism. The direct pressure type mold clamping mechanism means a mold clamping cylinder.

[0017] The servo motor 80C is provided inside the mold clamping housing 13. The servo motor 80C drives the mold clamping mechanism 16 via the ball screw 19. The ball screw 19 converts the rotational motion from the servo motor 80C into a linear motion to drive the mold clamping mechanism 16. The molds 17, 18 are provided between the fixed platen 12 and the movable platen 14. The molds 17, 18 are opened and closed when the mold clamping mechanism 16 is driven.

[0018] The process of transitioning from the state where the molds 17, 18 are separated to the state where they are in close contact is referred to as the "mold closing process". Also, the process of transitioning from the state where the molds 17, 18 are in close contact to the state where they are separated is referred to as the "mold opening process". The servo motor 80C is a motor used in the mold closing process and the mold opening process. Hereinafter, the servo motor 80C may be referred to as the "mold opening / closing motor 80C".

[0019] The injection molding machine 100 performs a process called the "ejection process" after the mold opening process. The ejection process is the process of removing the injection material, such as resin, that has been filled into the molds 17 and 18 and solidified, from the mold 17. Specifically, the ejection motor 80D rotates and pins (not shown) or the like are ejected, thereby removing the molded product that is in close contact with the mold 17. The servo motor 80D, located in the movable platen 14, is the motor used in the ejection process. .sa The 80D motor is sometimes referred to as the "80D protruding motor."

[0020] <Injection device> The injection device 20 comprises a base 21, a heating cylinder 22, a screw 23, a drive mechanism 24, a hopper 25, an injection nozzle 26, a nozzle touch device 27, thermocouples 29A to 29C, and servo motors 80A and 80B. The base 21 is positioned on the positive X-axis side of the bed 11 and holds the drive mechanism 24, etc. The servo motors 80A and 80B are located within the drive mechanism 24.

[0021] The screw 23 is positioned inside the heating cylinder 22. The injection molding machine 100 uses the screw 23 to perform a process called the "plasticization process." The plasticization process is a process in which the resin to be injected is mixed by heating by the heating cylinder 22 and rotation of the screw 23. Movement mechanism 2 The servo motor 80B inside 4 rotates the screw 23 with the X-axis as its central axis. In other words, the servo motor 80B is a motor used in the plasticization process. Hereafter, the servo motor 80B may be referred to as the "plasticization motor 80B".

[0022] Furthermore, the injection molding machine 100 performs a process called the "injection process" and a process called the "holding pressure process." The injection process is the process of injecting the resin, which has been plasticized by the plasticization process, into the molds 17 and 18. The holding pressure process is the process of applying pressure to hold the resin injected in the injection process inside the molds 17 and 18. Driven by the servo motor 80A, the screw 23 slides to the negative direction in the X-axis direction. As a result, the plasticized resin is injected into the molds 17 and 18 by the screw 23. The servo motor 80A is a motor used in the injection process or the holding pressure process. Hereafter, the servo motor 80A may be referred to as the "injection motor 80A."

[0023] The hopper 25 is located on the positive Z-axis side of the heating cylinder 22. The injection nozzle 26 is located at the negative X-axis end of the heating cylinder 22. The nozzle touch device 27 slides the injection device 20 in the X-axis direction to bring the injection nozzle 26 into contact with the sprue bush of the mold 18. Thermocouples 29A to 29C may be placed near the injection nozzle 26 and near the heating cylinder 22. Thermocouples 29A to 29C are temperature sensors that detect the temperature at the location where they are placed.

[0024] The base 21 houses control devices 40A to 40D and servo amplifiers 50A to 50D. The servo amplifiers 50A to 50D supply power to the servo motors 80A to 80D, respectively. More specifically, the servo amplifiers 50A to 50D generate a three-phase AC voltage and supply this three-phase AC power to the corresponding servo motors. The control devices 40A to 40D control the servo amplifiers 50A to 50D, respectively, to execute the molding cycle. Each of the control devices 40A to 40D is electrically connected to the others.

[0025] The control panel 30 displays information related to the injection molding machine 100 and accepts user input. The control panel 30 is electrically connected to at least one of the control devices 40A to 40D. In the example shown in Figure 1, the control panel 30 is located on the negative side of the Y-axis of the injection molding machine 100. In some cases, the control panel 30 may be located separately from the injection molding machine 100, for example, in a different room from the room in which the injection molding machine 100 is located.

[0026] The control panel 30 comprises a display 31 and an input device 32. The input device 32 is configured, for example, to include a number of buttons. In some cases, the display 31 and the input device 32 may be integrated as a touch panel. The control panel 30 may also include a microphone and a speaker to accept user input using voice commands.

[0027] <Schematic block diagram of an injection molding machine> Figure 2 is a schematic block diagram of the injection molding machine 100 in Embodiment 1. As shown in Figure 2, the injection molding machine 100 includes the control devices 40A to 40D described in Figure 1, servo amplifiers 50A to 50D, and servo motors 80A to 80D.

[0028] As explained in Figure 1, servo amplifier 50A and servo motor 80A are used in the injection process. Servo amplifier 50B and servo motor 80B are used in the plasticization process. Servo amplifier 50C and servo motor 80C are used in the mold opening and closing process. Servo amplifier 50D and servo motor 80D are used in the ejection process. Power supply lines for driving servo motors 80A to 80D are shown between each of the servo amplifiers 50A to 50D and servo motors 80A to 80D. The diagram of the power grid is omitted in Figure 1.

[0029] The internal configuration of control device 40A will be described below. Note that control devices 40B to 40C have the same internal configuration as control device 40A, as shown in Figure 2; therefore, the description of the internal configuration of control devices 40B to 40C will not be repeated. Furthermore, in the internal configurations of control devices 40B to 40C, the same reference numerals are used for parts that are identical or equivalent to those in the internal configuration of control device 40A. Control device 40A comprises a control unit 41, an output interface 43, and a storage device 44. The control unit 41 of control device 40A is connected to the servo amplifier 50A so as to be able to transmit control signals via the output interface 43. The control unit 41 of control device 40A transmits control signals to the servo amplifier 50A to control the state of the switching element, which will be described later.

[0030] The control unit 41 comprises a CPU 41a and a memory 41b. The CPU 41a loads programs stored in ROM (Read Only Memory) into RAM (Random Access Memory) and executes them. The memory 41b includes both ROM and RAM and stores programs and other data executed by the CPU 41a.

[0031] In some cases, the control unit 41 may be configured by a dedicated hardware circuit. That is, the control unit 41 may be implemented by an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), etc. Alternatively, the control unit 41 may be implemented by appropriately combining a processor, memory, ASIC, FPGA, etc. The storage device 44 may be configured to include, for example, an HDD (Hard Disk Drive) or an SSD (Flash Solid State Drive).

[0032] <Explanation of electrical circuits> Figure 3 shows the details of the electrical circuit configuration in the servo amplifier 50A of Embodiment 1. In Figure 3, the electrical circuit configuration of servo amplifier 50A is explained as an example, but servo amplifiers 50B to 50D have the same electrical circuit configuration as servo amplifier 50A.

[0033] One end of the servo amplifier 50A is electrically connected to the servo motor 80A, and the other end of the servo amplifier 50A is electrically connected to the AC / DC converter Cv1 via the DC bus 260. The AC / DC converter Cv1 includes a three-phase full-bridge type PWM rectifier.

[0034] The AC / DC converter Cv1 converts AC power supplied from the grid power supply 200 into DC power and supplies the converted DC power to the DC bus 260. The DC bus 260 includes two power lines PL1 and NL1. The AC / DC converter Cv1 also has a high-frequency noise generator. Remove the minutes Filter circuits and step-up transformers may be included for removal, but these are omitted in the example in Figure 3 for simplicity of explanation. In the DC bus 260, a smoothing capacitor is placed between the power lines PL1 and NL1.

[0035] The servo amplifier 50A includes a three-phase full-bridge type inverter Iv1. The inverter Iv1 includes switching elements U1, U2, V1, V2, W1, and W2 arranged between the power lines PL1 and NL1 of the DC bus 260. Hereinafter, the switching elements U1, U2, V1, V2, W1, and W2 will be collectively referred to as "switching elements U1 to W2". In addition, the switching elements U1, V1, and W1 may be collectively referred to as the "upper arm", and the switching elements U2, V2, and W2 may be collectively referred to as the "lower arm". Switching element U1 may correspond to the "first switching element" in this disclosure. Switching element V1 may correspond to the "second switching element" in this disclosure.

[0036] In inverter Iv1, switching elements U1, V1, W1 and switching elements U2, V2, W2 switch complementaryly. That is, when switching element U1 is ON, switching element U2 is OFF.

[0037] The U-phase of the servo motor 80A is connected to the connection nodes of switching elements U1 and U2, which are connected in series between power lines PL1 and NL1. The V-phase of the servo motor 80A is connected to the connection nodes of switching elements V1 and V2, which are connected in series between power lines PL1 and NL1. The W-phase of the servo motor 80A is connected to the connection nodes of switching elements W1 and W2, which are connected in series between power lines PL1 and NL1.

[0038] As explained in Figure 2, the servo amplifier 50A is controlled by the control device 40A of the injection molding machine 100. Specifically, the control device 40A sends control signals to each of the switching elements U1 to W2 to control the state of each of the switching elements U1 to W2. As a result, the servo amplifier 50A converts the DC power from the DC bus 260 into AC power to drive the servo motor 80A.

[0039] The switching elements U1 to W2 are metal oxide semiconductor field-effect transistors (MOSFETs) or insulated-gate bipolar transistors (IGBTs), etc. The control unit 41 turns on the switching elements U1 to W2 by applying a gate voltage to the control terminals (gate terminals) of the switching elements U1 to W2 as a control signal. When a gate voltage is applied to the switching elements U1 to W2, power is consumed. Power is consumed due to losses due to gate resistance and losses due to switch resistance.

[0040] <Operation of switching elements> Figure 4 is a diagram illustrating the operation of switching elements U1 to W2. In this embodiment, the servo motor 80A is controlled by three control methods. Specifically, the servo motor 80 is configured to perform motor rotation control, zero-speed control, and servo-off control as shown in Figure 4. Motor rotation control may correspond to the "first control" in this disclosure. Servo-off control may correspond to the "second control" in this disclosure. Zero-speed control may correspond to the "third control" in this disclosure. Note that zero-speed control may include position control, which will be described later. That is, if the control device 40A detects the rotation of the servo motor while zero-speed control is being performed, it may return the angle of the servo motor to a predetermined angle.

[0041] Motor rotation control is the control of rotating the servo motor 80A. The control device 40A switches each of the switching elements U1 to W2 at the timing when the servo motor 80A is rotated by, for example, 120 degrees of energization. In other words, motor rotation control is the control of rotating the servo motor 80A by controlling the switching elements U1, V1, and W1 of the upper arm to be turned on at different phases. When motor rotation control is performed, the switching elements U1 to W2 consume power due to the application of gate voltage and consume power supplied from the grid power supply and used to drive the servo motor 80A.

[0042] Zero-speed control is a control method that stops the rotation of the servo motor 80A so that its rotational speed is kept at zero. In other words, zero-speed control is a control method that stops the rotation of the servo motor 80A by having each of the switching elements U1 to W2 repeatedly switch between the on state and the off state in the same phase.

[0043] In the zero-speed control example shown in Figure 4, the control device 40A repeatedly alternates between periods in which the upper arm is turned off and the lower arm is turned on, and periods in which the upper arm is turned on and the lower arm is turned off, all in the same phase. As a result, the voltage values ​​of the U, V, and W phases of the servo motor 80A become the same, and the servo motor 80A stops rotating.

[0044] In the example of zero-speed control shown in Figure 4, the switching elements U1 to W2 are shown to be repeatedly switched between the ON and OFF states. However, during the period when zero-speed control is performed, the switching elements U1, V1, and W1 of the upper arm may always be in the ON state, and the switching elements U2, V2, and W2 of the lower arm may always be in the OFF state. Alternatively, during the period when zero-speed control is performed, the switching elements U1, V1, and W1 of the upper arm may always be in the OFF state, and the switching elements U2, V2, and W2 of the lower arm may always be in the ON state. In other words, during the zero-speed control period, the switching of the switching elements U1 to W2 does not necessarily have to be repeated.

[0045] During zero-speed control, when an external force is applied to the servo motor 80A and its rotation angle changes, at least one of the switching elements U1 to W2 is in the ON state, generating a force that suppresses the change in rotation angle of the servo motor 80A. As a result, the servo motor 80A can stop while maintaining its rotation angle. As shown in Figure 4, when zero-speed control is performed, a gate voltage is applied to at least one of the switching elements U1 to W2, resulting in power consumption.

[0046] Servo-off control is a control method that stops the rotation of the servo motor 80A without applying any force. As shown in Figure 4, the control device 40A turns off all of the switching elements U1, V1, and W1. In other words, servo-off control is a control method that stops the rotation of the servo motor 80A by turning off each of the switching elements U1 to W2.

[0047] If an external force is applied to the servo motor 80A during servo-off control, the rotation angle of the servo motor 80A will change due to this external force. On the other hand, as shown in Figure 4, when servo-off control is performed, no gate voltage is applied to the switching elements U1 to W2, so no power is consumed. In Figure 4, the control devices 40A were used to explain each control, but the control devices 40B to 40D are similarly configured to perform motor rotation control, zero-speed control, and servo-off control on the servo amplifiers 50B to 50D.

[0048] <Molding Cycle> Figure 5 is a diagram illustrating the molding cycle in Embodiment 1. As described above, the injection molding machine 100 in this embodiment continuously repeats the molding cycle to produce multiple molded products. Figure 5 shows the control of each of the servo motors 80A to 80D within one molding cycle.

[0049] The molding cycle includes a mold closing step, an injection step, a holding pressure step, a plasticizing step, a mold opening step, a cooling step, and an ejection step. The cooling step is a step to cool the injection material in the mold 17 after the mold opening step in order to solidify it. In the injection molding machine 100 of this embodiment, a cooling device (not shown) may be used to cool the injection material during the cooling step.

[0050] As shown in Figure 5, injection molding is performed by driving each servo motor 80A to 80D in a predetermined order at predetermined timings within a single molding cycle. In Figure 5, the period during which each servo motor 80A to 80D is driven is shown as the "motor rotation period". The motor rotation period is predetermined for each servo motor 80A to 80D based on molding conditions such as the shape and material of the molded product. Hereinafter, the period other than the "motor rotation period" during the molding cycle will be referred to as the "motor stop period". In this embodiment, either zero-speed control or servo-off control is performed during the motor stop period. The motor rotation period may correspond to the "first period" in this disclosure. The motor stop period may also correspond to the "second period" in this disclosure.

[0051] During the mold closing process at timings t0 to t1, the mold opening / closing motor 80C rotates, causing the molds 17 and 18 to come into close contact. After the mold closing process is complete, during the injection process at timings t1 to t2, the injection motor 80A rotates, injecting the material into the mold. That is, the screw 23 slides in the negative direction of the X-axis, injecting the material into the mold. After the injection process is complete, during the holding pressure process at timings t2 to t3, none of the servo motors 80A to 80D are driven.

[0052] After the holding pressure process is completed, during the mold opening process at timings t3 to t4, the mold opening / closing motor 80C rotates, separating the molds 17 and 18. During the plasticizing process at timings t3 to t5, the rotation of the injection motor 80A causes the screw 23 to slide in the positive direction of the X-axis. The movement speed of the screw 23 during the plasticizing process is slower than that of the screw 23 during the injection process, as the purpose is to return the screw 23 to its original position.

[0053] In the plasticization process, the plasticizing motor 80B rotates the screw 23 with the X-axis as its central axis. This kneads the injection material to be used in the next molding cycle. Finally, in the ejection process at timings t5 to t6, the ejection motor 80D rotates, causing pins (not shown) to protrude, thereby removing the molded product that is in close contact with the mold 17.

[0054] As shown in Figure 5, the motor rotation period of the injection motor 80A is during the timings t1-t2 and t3-t5. The motor rotation period of the plasticizing motor 80B is during the timings t3-t5. The motor rotation period of the mold opening / closing motor 80C is during the timings t0-t1 and t3-t4. The motor rotation period of the ejection motor 80D is during the timings t5-t6.

[0055] <Zero-speed control and servo-off control> In the injection molding machine 100 of Embodiment 1, it is predetermined whether each servo motor 80A to 80D performs zero-speed control or servo-off control during the motor stop period, which is not the motor rotation period. Specifically, as shown in Figure 5, the injection motor 80A performs servo-off control during the mold closing and ejection processes, and zero-speed control during the holding pressure process. The plasticizing motor 80B performs servo-off control during all processes except the plasticizing process.

[0056] In the mold opening / closing motor 80C, zero-speed control is performed during the injection, holding pressure, and ejection processes, and servo-off control is performed during the cooling process. In the ejection motor 80D, servo-off control is performed during all processes except the ejection process. Hereafter, as shown in Figure 5, the period during which servo-off control is performed will be referred to as the "servo-off period," and the period during which zero-speed control is performed will be referred to as the "zero-speed period."

[0057] The holding pressure process involves fixing the screw 23, which slid to the negative X-axis side during the injection process, and applying pressure to the injection material in the molds 17 and 18. During the holding pressure process, a force is generated on the screw 23 that tries to push it back towards the positive X-axis side due to the reaction force from the injection material to which pressure is applied. Therefore, in the injection molding machine 100 of Embodiment 1, zero speed control is applied to the injection motor 80A during the holding pressure process to suppress the screw 23 from being pushed back towards the positive X-axis side and losing pressure on the injection material.

[0058] During the injection process, a reaction force is generated from the injection material for the same reasons as in the holding pressure process. This reaction force, which applies pressure to the injection material, occurs not only on the screw 23 but also on the molds 17 and 18. Specifically, the injection material, under pressure within the molds 17 and 18, exerts a force on the molds 17 and 18 that causes them to separate. Therefore, as shown in Figure 5, the control unit 41 of the control device 40C performs zero-speed control on the mold opening / closing motor 80C during both the injection process and the holding pressure process. As a result, in the injection molding machine 100 of Embodiment 1, the position of the molds 17 and 18 can be maintained against the reaction force from the injection material during the injection process and the holding pressure process.

[0059] As shown in Figure 1, the ejection motor 80D is located inside the movable platen 14. The molded product, which is in close contact with the mold 17, is removed when the pins are ejected by the drive of the ejection motor 80D. However, the movable platen 14 may move in the X-axis direction due to the reaction force caused by the ejection of the pins. Therefore, as shown in Figure 5, zero-speed control is performed on the mold opening / closing motor 80C during the ejection process driven by the ejection motor 80D. In Embodiment 1, an example was described in which the control devices 40A to 40D each control the servo amplifiers 50A to 50D, but the servo amplifiers 50A to 50D may be controlled by a single control device. That is, the control devices 40A to 40D do not each have to be provided as separate units, but may be provided as a single control device.

[0060] Thus, in the injection molding machine 100 of Embodiment 1, zero-speed control is performed only during periods when external forces can be generated for each servo motor 80A to 80D, and servo-off control is performed during periods when no external forces are generated from other components of the injection molding machine 100. As a result, compared to the case where zero-speed control is performed for the entire duration of the motor stop period, the period during which all switching elements U1 to W2 are in the off state is extended, thereby suppressing power consumption. In other words, in the injection molding machine 100 of Embodiment 1, it is possible to suppress the unintended change in the rotation angle of each servo motor 80A to 80D due to external forces, and to stop the rotation of each servo motor 80A to 80D while reducing power consumption.

[0061] <Embodiment 2> Embodiment 1 described an example in which the zero-speed period and servo-off period in the molding cycle are predetermined. However, as mentioned above, the motor rotation period in the molding cycle changes depending on the molding conditions such as the shape of the molded product and the material of the injection material, so it is necessary to redefine the zero-speed period and servo-off period for each molding condition. Embodiment 2 describes a method for automatically determining the zero-speed period and servo-off period within the molding cycle by performing a test cycle. Note that in Embodiment 2, the same configuration as in Embodiment 1 will not be repeated in the description.

[0062] Figure 6 is a schematic block diagram of the injection molding machine 100A in Embodiment 2. In the injection molding machine 100A, a current sensor is provided for each of the servo motors 80A to 80D. In Embodiment 2, each of the servo amplifiers 50A to 50D is controlled by a single control device 40. In some cases, the injection molding machine 100A in Embodiment 2 may also be provided with control devices 40A to 40D that control each of the servo amplifiers 50A to 50D, as described in Embodiment 1. In that case, see below. ExplainedThe flowchart shown in Figure 7 may be executed by any one of the control devices 40A to 40D, or by another control device that comprehensively controls the control devices 40A to 40D. As shown in Figure 6, the injection molding machine 100A includes a control device 40, servo amplifiers 50A to 50D, servo motors 80A to 80D, and current sensors 81A to 81D. In addition, the control device 40 includes an input interface 42 in addition to an output interface 43.

[0063] Current sensors 81A to 81D detect the motor current of servo motors 80A to 80D, respectively. Current sensors 81A to 81D transmit the detected current values ​​to the control unit 41 via the input interface 42. In servo motors 80A to 80D, the motor current is correlated with the torque generated by the motor. The memory device 44 stores the torque values ​​associated with the current values ​​detected by current sensors 81A to 81D. That is, the control unit 41 controls the servo motor 80A based on the detected values ​​of current sensors 81A to 81D. It is possible to estimate the torque generated in the ~80D. 。

[0064] <Method for determining zero-speed period and servo-off period using test cycles> Figure 7 is a flowchart showing the processing procedure for determining the zero-speed period and the servo-off period. The flowchart shown in Figure 7 is stored as a program in the storage device 44, and this program is executed by the control unit 41.

[0065] In Embodiment 2, a test cycle is performed before starting the molding cycle. The test cycle is an experimental cycle having the same motor rotation period and motor stop period as the molding cycle. In Embodiment 2, the zero-speed period and servo-off period are determined based on the torque generated during the motor stop period in the test cycle. Before executing the molding cycle, the control unit 41 executes the flowchart shown in Figure 7.

[0066] The control unit 41 executes a test cycle (step S100). The test cycle is a cycle in which zero-speed control is performed for the entire duration of the motor stop period. Figure 8 is a diagram illustrating the test cycle in Embodiment 2. As shown in Figure 8, in the test cycle, servo-off control is not performed; only motor rotation control and zero-speed control are performed. The "motor rotation period" shown in Figure 8 may correspond to the "third period" in this disclosure. The "zero-speed period" shown in Figure 8 may correspond to the "fourth period" in this disclosure.

[0067] Returning to Figure 7, the control unit 41 determines whether the test cycle has finished (step S110). If the test cycle has not finished (NO in step S110), the control unit 41 repeats the process in step S110. If the test cycle has finished (YES in step S110), the control unit 41 obtains the detection results of the current sensors 81A to 81D during the test cycle performed in step S100 (step S120).

[0068] The control unit 41 determines the zero-speed period and servo-off period for each servo motor 80A to 80D in the molding cycle based on the detected values ​​of the current sensors 81A to 81D (step S130). In step S130, the control unit 41 determines whether the detection result of the current sensors 81A to 81D was above a predetermined threshold during a specific period within the motor stop period. If the current value detected during the specific period is above the predetermined threshold, the control unit 41 determines that torque was generated by an external force during that specific period. In this case, the control unit 41 determines the period within the molding cycle corresponding to that specific period as the zero-speed period.

[0069] On the other hand, if the current value detected within a specific period is less than a predetermined threshold, the control unit 41 determines that no torque was generated due to external force during that specific period. In this case, the control unit 41 sets the period within the molding cycle corresponding to that specific period as the servo-off period. The specific period may be a period representing one process, or it may be a period of one second within the motor stop period.

[0070] To explain using a more specific example, in the holding pressure process from timing t2 to timing t3 shown in Figure 8, if the control unit 41 determines from the detected value of the current sensor 81A that an external force has been generated on the injection motor 80A, it sets the holding pressure process in the molding cycle as a zero-speed period. On the other hand, in the mold closing process from timing t0 to timing t1 shown in Figure 8, if the control unit 41 determines from the detected value of the current sensor 81A that no external force has been generated on the injection motor 80A, it sets the holding pressure process in the molding cycle as a servo-off period.

[0071] Thus, the control unit 41 determines the zero-speed period and servo-off period for each servo motor 80A to 80D in the molding cycle based on the detection results of the current sensors 81A to 81D during the test cycle. The control unit 41 executes the molding cycle according to the zero-speed period and servo-off period determined in S130 (step S 140). In this embodiment 2, the zero-speed period and servo-off period in the molding cycle can be determined based on a test cycle used to determine whether or not an external force actually occurred. Furthermore, in embodiment 2, since the user does not need to consider whether or not an external force occurs during each period, the zero-speed period and servo-off period in the molding cycle can be automatically determined simply by performing a test cycle.

[0072] <Embodiment 3> Embodiment 2 describes a method for automatically determining the zero-speed period and the servo-off period by performing a test cycle in advance before executing the molding cycle. However, sudden external forces such as earthquakes, accidents, and failures of components constituting the injection molding machine 100 may occur during the servo-off period determined by the test cycle. Embodiment 3 describes a method for determining whether to perform zero-speed control or servo-off control in real time using a speed sensor that detects the rotational speed of the motor. Note that in Embodiment 3, the same configuration as in Embodiment 2 will not be repeated in the description.

[0073] Figure 9 is a schematic block diagram of the injection molding machine 100B in Embodiment 3. In the injection molding machine 100B, a position sensor is provided for each of the servo motors 80A to 80D. Specifically, as shown in Figure 9, the injection molding machine 100B is further equipped with position sensors 84A to 84D in addition to the configuration of Embodiment 2.

[0074] Position sensors 84A to 84D are, for example, optical encoders. Position sensors 84A to 84D detect the rotational speed of servo motors 80A to 80D, respectively. Position sensors 84A to 84D also detect the rotational angle of servo motors 80A to 80D, respectively. In some cases, position sensors 84A to 84D may not be a single optical encoder, but rather separate sensors: a speed sensor for detecting rotational speed and an angle sensor for detecting rotational angle.

[0075] The position sensors 84A to 84D transmit the results they detect to the control unit 41 via the input interface 42. This allows the control unit 41 to obtain the rotation speed and rotation angle of the servo motors 80A to 80D.

[0076] <Switching between zero-speed control and servo-off control> Figure 10 is a flowchart showing the process for switching between zero-speed control and servo-off control in Embodiment 3. In Embodiment 3, the control unit 41 performs zero-speed control only for the required period by executing the flowchart shown in Figure 10 without performing a test cycle.

[0077] The flowchart shown in Figure 10 illustrates the processing steps for executing one molding cycle. The control unit 41 executes the flowchart shown in Figure 10 separately for each of the servo motors 80A to 80D. In Embodiment 3 as well, the motor rotation period is predetermined according to the molding conditions.

[0078] The control unit 41 determines whether or not it is a motor rotation period after the start of the molding cycle (step S200). If it is a motor rotation period (YES in step S200), the control unit 41 executes the motor rotation control described in Figure 4 (step S201). For example, when executing the flowchart in Figure 10 for the mold opening / closing motor 80C, the motor rotation period begins immediately after the start of the molding cycle, as shown in Figure 5. In the flowchart in Figure 11, after the motor rotation control is executed in step S201, the motor rotation control continues to be executed until zero speed control or servo off control is performed, or until one cycle is completed.

[0079] Next, the control unit 41 determines whether or not one molding cycle has been completed (step S202). If the control unit 41 determines that one molding cycle has not been completed (NO in step S202), it returns to step S200.

[0080] Subsequently, the control unit 41 determines again whether or not it is a motor rotation period (step S200). If it is not a motor rotation period (NO in step S200), the control unit 41 performs zero-speed control (step S203). For example, when executing the flowchart in Figure 10 for the type switching motor 80C, the control unit 41 repeats steps S200, 201, and 202 during the period from timing t0 to t1 in Figure 5. Since the motor rotation period ends at timing t1, the control unit 41 of Embodiment 3 performs zero-speed control for the type switching motor 80C (step S203). In the flowchart in Figure 11, after zero-speed control is performed in step S203, zero-speed control continues to be performed until motor rotation control or servo-off control is performed, or until one cycle is completed.

[0081] Next, the control unit 41 resets the timer (step S204). The timer in step S204 is, for example, a general-purpose timer mounted on the CPU 41a. In this embodiment, resetting the timer means returning the timer count to its initial value (0 seconds) and starting the count again.

[0082] Next, the control unit 41 determines whether or not it is the motor rotation period (step S205). If it is not the motor rotation period (NO in step S205), the control unit 41 determines whether or not the timer value has reached 100ms (step S206). If the timer value has not reached 100ms (NO in step S206), the control unit 41 determines whether or not it is the motor rotation period (step S205). If the motor rotation period is reached before the timer value reaches 100ms (YES in step S205), the control unit 41 performs motor rotation control (step S201).

[0083] When the timer value reaches 100ms (YES in step S206), the control unit 41 determines whether or not torque was detected during the 100ms period measured by the timer from step S204 (step S207). That is, the memory device 44 or memory 41b stores the value detected by the current sensor during the 100ms period measured by the timer from step S204. The control unit 41 determines whether or not the value detected by the current sensor during the 100ms period measured by the timer from step S204 was above a predetermined threshold.

[0084] If the control unit 41 detects torque during the 100ms period measured by the timer from step S204 (YES in step S207), it assumes that an external force occurred during the most recent 100ms period and returns the process to step S204. In other words, the control unit 41 continues zero-speed control for another 100ms.

[0085] In step S207, if no torque is detected during the 100ms period measured by the timer from step S204 (NO in step S207), the control unit 41 assumes that no external force was generated during the most recent 100ms period and switches from zero-speed control to servo-off control (step S208). In the flowchart of Figure 11, after the servo-off control is executed in step S208, the servo-off control continues to be executed until motor rotation control or zero-speed control is performed, or until one cycle is completed.

[0086] In other words, since no external force was generated in the most recent 100ms period, there is a possibility that no external force will be generated in the next 100ms period as well. Therefore, in order to reduce power consumption, the control unit 41 switches from zero-speed control to servo-off control. Specifically, the control unit 41 switches from zero-speed control to servo-off control if no torque is detected for a period of 100ms during the period in which zero-speed control is being performed.

[0087] After switching from zero-speed control to servo-off control, the control unit 41 obtains the rotation angle of the servo motor from the position sensor's detected value (step S209). That is, the control unit 41 stores the servo motor's rotation angle immediately after switching to servo-off control in the storage device 44 or memory 41b.

[0088] The control unit 41 resets the timer (step S210). The control unit 41 determines whether or not it is the motor rotation period (step S211). If it is not the motor rotation period (NO in step S211), the control unit 41 determines whether or not the timer value has reached 100ms (step S212). If the timer value has not reached 100ms (NO in step S212), the control unit 41 determines whether or not the motor rotation period was reached before the timer value reached 100ms (step S211). If the motor rotation period was reached before the timer value reached 100ms (YES in step S211), the control unit 41 performs motor rotation control (step S201).

[0089] When the timer value reaches 100ms (YES in step S212), the control unit 41 determines whether or not rotational speed was detected during the 100ms period measured by the timer from step S210 (step S213). That is, it determines whether or not the value of the position sensor during the 100ms period measured by the timer from step S210 was above a predetermined threshold. In step S213, unlike step S207, the control unit 41 performs servo-off control. Therefore, if an external force is applied to the servo motor, the servo motor rotates due to the external force, and rotational speed is generated.

[0090] If the control unit 41 detects a rotational speed during the 100ms period measured by the timer from step S210 (YES in step S214), it controls the position of the servo motor to the rotational angle acquired in step S208 (step S214). This allows the control unit 41 to return the rotational angle of the servo motor, which has been rotated by an external force, back to the rotational angle it was at before the external force occurred.

[0091] The control unit 41, assuming that an external force occurred in the most recent 100ms, switches from servo-off control to zero-speed control (step S203). In other words, because an external force occurred in the most recent 100ms, there is a possibility that an external force may occur in the next 100ms, and in order to fix and stop the servo motor, the control unit 41 switches from servo-off control to zero-speed control.

[0092] If the control unit 41 does not detect the rotation speed during the 100ms period measured by the timer from step S210 (NO in step S213), it returns to step S211. That is, the control unit 41 continues to perform servo-off control for another 100ms. Note that the waiting period shown in steps S206 and S212 is not limited to 100ms, but may be other periods such as 10ms or 500ms.

[0093] Although not shown in Figure 10, in steps S205 and S211, the control unit 41 also determines whether it is the motor rotation period or whether one cycle has ended. If it determines in steps S205 and S211 that one cycle has ended, the control unit 41 terminates the process.

[0094] Thus, in the injection molding machine 100 of Embodiment 3, the zero-speed period and servo-off period are not predetermined by the test cycle or the user. By detecting the rotational speed, the external force generated during the servo-off period is detected, and the system switches from servo-off control to zero-speed control in real time. This allows the injection molding machine 100 in Embodiment 3 to switch between servo-off control and zero-speed control at the appropriate timing. In Embodiment 3, control devices 40A to 40D that control each of the servo amplifiers 50A to 50D may also be provided. In that case, the flowchart in Figure 10 may be executed by any one of the control devices 40A to 40D, or by another control device that comprehensively controls the control devices 40A to 40D.

[0095] <Example 1> In Embodiment 2, the zero-speed period and the servo-off period were determined based on the test cycle, while in Embodiment 3, the zero-speed control and servo-off control were switched based on the position sensors 84A to 84D. Modification 1 describes a configuration that combines Embodiment 2 with Embodiment 3.

[0096] The injection molding machine 100 of Modified Example 1 has the same configuration as Embodiment 3 shown in Figure 9. That is, the injection molding machine 100 of Modified Example 1 has position sensors 84A to 84D. In the injection molding machine 100 of Modified Example 1, the flowchart showing the processing procedure of the test cycle described in Figure 7 is executed. This determines the zero-speed period and the servo-off period during the motor stop period.

[0097] In the modified example 1, the injection molding machine 100 prioritizes the zero-speed period and servo-off period determined based on the test cycle, and switches between zero-speed control and servo-off control when an external force is detected. Figure 11 is a flowchart showing the process of switching between zero-speed control and servo-off control in the modified example 1.

[0098] The flowchart in Figure 11 has the same configuration as the flowchart in Figure 10, but with the addition of step S300. If it is not a motor rotation period (NO in step S200), the control unit 41 determines whether it is a zero-speed period as defined in S130 (step S300). That is, if it is a motor stop period, the control unit 41 determines whether it is a zero-speed period or a servo-off period based on the test cycle.

[0099] If it is during the zero-speed period (YES in step S300), the control unit 41 performs zero-speed control (step S203). Subsequently, if an external force is detected based on the current sensor, the control unit 41 switches from zero-speed control to servo-off control. If it is not during the zero-speed period (NO in step S300), the control unit 41 performs servo-off control (step S208). Subsequently, if an external force is detected based on the position sensor, the control unit 41 switches from servo-off control to zero-speed control.

[0100] Thus, the injection molding machine 100 of Modified Example 1 can automatically determine the zero-speed period and the servo-off period using a test cycle, and can appropriately switch between zero-speed control and servo-off control in real time even when sudden external forces such as earthquakes, accidents, and failures of components constituting the injection molding machine 100 occur.

[0101] <Modification 2> Embodiment 2 describes an example in which the zero-speed period and servo-off period are defined for all molding cycles performed in the injection molding process, based on a test cycle. Modification 2 describes an example in which the zero-speed period and servo-off period are updated for each cycle.

[0102] The injection molding machine 100 in Modification 2 has the same configuration as in Embodiment 3 shown in Figure 9. Figure 12 is a flowchart showing the processing procedure for the injection molding process in Modification 2. In Modification 2, as in Embodiment 2, a test cycle is performed before starting the molding cycle.

[0103] The test cycle in Modification 2 is an experimental cycle having the same motor rotation period and motor stop period as the molding cycle. The control unit 41 executes the test cycle (step S400). The test cycle in Modification 2 is a cycle in which zero speed control is performed for the entire duration of the motor stop period, similar to Embodiment 2.

[0104] The control unit 41 determines whether the test cycle has finished (step S410). If the test cycle has not finished (NO in step S410), the control unit 41 repeats the process in step S410. If the test cycle has finished (YES in step S410), the control unit 41 obtains the detected values ​​of the current sensors 81A to 81D and the speed sensors 82A to 82D during the most recent cycle (step S420).

[0105] When step S420 is executed for the first time after starting the flowchart in Figure 12, the most recent cycle is the test cycle executed in step S400. As mentioned above, servo-off control is not performed during the test cycle. Therefore, in step S420, the control unit 41 determines whether or not an external force has occurred based on the value detected by the current sensor.

[0106] The control unit 41 determines the zero-speed period and the servo-off period in the next cycle based on the detected value of the current sensor and the detected value of the position sensor (step S 430). That is, the control unit 41 defines a specific period during which an external force occurs as a zero-velocity period, and a specific period during which no external force occurs as a servo-off period.

[0107] The control unit 41 executes a new cycle according to the zero-speed period and servo-off period defined in step S430 (step S440). The control unit 41 determines whether the new cycle executed in S440 has finished (step S450). If the new cycle executed in S440 has not finished (NO in step S450), the control unit 41 repeats step S450.

[0108] If the new cycle executed in S440 is completed (YES in step S450), the control unit 41 determines whether the injection molding process is completed or not (step S460). If the injection molding process is not completed (NO in step S460), the control unit 41 moves the process to step S420.

[0109] At this time, the control unit 41 determines the zero-speed period and servo-off period in the next cycle based on a specific period during which an external force occurred in the new cycle executed in step S440, rather than the test cycle. When the injection molding process is completed (YES in step S460), the control unit 41 terminates the process.

[0110] Thus, the injection molding machine 100 of Modified Example 2 updates the zero-speed period and the servo-off period with each cycle. This allows the injection molding machine 100 of Modified Example 2 to determine the zero-speed period and the servo-off period based on the latest data.

[0111] [Note] Those skilled in the art will understand that the above-described exemplary embodiments are specific examples of the following embodiments.

[0112] (Section 1) The injection molding machine 100 in this disclosure comprises a servo motor 80A, a servo amplifier 50A that supplies power to the servo motor, and a control device 40 that controls the servo amplifier 50A to execute a molding cycle. Servo amplifier 50A is, Wetting element U1 And,It includes a switching element V1. The molding cycle includes a motor rotation period in which the servo motor 80A is rotated and a motor stop period in which the servo motor 80A is not rotated. The servo motor 80A is configured to rotate by motor rotation control and to stop by servo off control or zero speed control. The motor rotation control is a control that rotates the servo motor 80A by controlling the switching element U1 and the switching element V1 to the ON state in different phases. Zero speed control is, This control mechanism controls switching element U1 and switching element V1 to be turned ON in the same phase, thereby stopping the rotation of the servo motor 80A. Servo-off control is, This control stops the rotation of the servo motor 80A by controlling switching elements U1 and V1 to the off state. The control device 40 performs motor rotation control during the motor rotation period and performs servo off control or zero speed control during the motor stop period.

[0113] According to the injection molding machine 100 described in paragraph 1, the purpose is to suppress the motor's rotation angle from changing unintentionally due to external forces, thereby reducing power consumption and stopping the motor.

[0114] (Section 2) The servo motor 80C relating to Section 1 is a mold opening and closing motor for opening and closing the mold. The control device 40 performs zero-speed control during the injection process in which the injection material is injected into the mold and during the holding pressure process in which pressure is maintained to hold the injected injection material inside the mold.

[0115] According to the injection molding machine 100 described in paragraph 2, it is possible to maintain the pressure applied to the injection material.

[0116] (Section 3) In Section 1, the servo motor 80A is an injection motor that injects the injection material into the mold. The control device 40 performs zero-speed control during the holding pressure process, which maintains pressure to hold the injected injection material in the molds 17, 18.

[0117] According to the injection molding machine 100 described in paragraph 3, it is possible to maintain the pressure applied to the injection material.

[0118] (Article 4) In any one of Articles 1 to 3, the system further comprises a servo motor 80D different from the servo motor 80C, and a servo amplifier 50D that supplies power to the servo motor 80D.

[0119] According to the injection molding machine 100 described in paragraph 4, the injection molding process can be performed by multiple servo motors.

[0120] (Section 5) In Section 4, the servo motor 80C is a mold opening / closing motor that opens and closes the molds 17 and 18. The servo motor 80D is an ejection motor that removes the molded product from the mold. The control device 40 performs zero-speed control on the servo motor 80C during the period when the servo motor 80D is driven.

[0121] According to the injection molding machine 100 described in paragraph 5, it is possible to prevent the movable platen 14 from moving unintentionally due to the drive of the ejection motor.

[0122] (Clause 6) The invention further comprises a current sensor 81A for detecting the torque generated in the servo motor 80A, as described in Clause 1.

[0123] According to the injection molding machine 100 described in paragraph 6, the generation of torque can be detected using a current sensor.

[0124] (Clause 7) In paragraph 6, the control device 40 rotates the servo motor 80A. Ta rotation period A test cycle including a motor stop period during which the servo motor 80A is not rotated is performed before the molding cycle is executed. During the motor stop period, zero speed control is performed (S100). Based on the current sensor's detection value during the motor stop period, the period during which servo-off control is performed during the motor rotation period and the period during which zero speed control is performed during the motor rotation period are determined (S130).

[0125] According to the injection molding machine 100 described in paragraph 7, the zero-speed period and the servo-off period can be determined based on the test cycle.

[0126] (Clause 8) In Clause 6 or 7, if the current sensor does not detect torque for a predetermined period (e.g., 100 ms) during the period in which zero speed control is being performed, the control device 40 switches from zero speed control to servo off control (S208).

[0127] According to the injection molding machine 100 described in paragraph 8, it is possible to switch from zero-speed control to servo-off control in real time when no external force is detected for a predetermined period of time.

[0128] (Clause 9) In any one of paragraphs 1, 6 to 8, the injection molding machine 100 is further equipped with a speed sensor for detecting the rotational speed of the servo motor 80A. If the speed sensor detects a rotational speed during the period in which the servo off control is being performed, the control device 40 switches from servo off control to zero speed control (S203).

[0129] According to the injection molding machine 100 described in paragraph 9, when an external force is detected, it is possible to switch from servo-off control to zero-speed control in real time.

[0130] (Section 10) In Section 9, the injection molding machine 100 further includes an angle sensor for detecting the rotation angle of the servo motor 80A and a storage device 44 for storing the detection result of the angle sensor. The control device 40 stores the detected value of the angle sensor in the storage device 44 when servo-off control is performed (S209), and when the speed sensor detects a rotation speed (YES in S213), it rotates the servo motor 80A to the rotation angle indicated by the detected value of the angle sensor stored in the storage device 44 (S214).

[0131] According to the injection molding machine 100 described in paragraph 10, the rotation angle of a motor that has been rotated by an external force can be returned to the rotation angle before the external force occurred.

[0132] (Clause 11) In any one of paragraphs 1, 6 to 8, the system further includes a position sensor 84A for detecting the rotational speed and rotational angle of the servo motor 80A. During the period in which the second control is being performed, if the position sensor 84A detects the rotational speed, the control device 40 switches from the second control to the third control, stores the detected value of the position sensor 84A when the second control was performed in the storage device 44, and if the position sensor 84A detects the rotational speed, rotates the servo motor 80A to the rotational angle indicated by the detected value of the position sensor 84A stored in the storage device 44.

[0133] According to the injection molding machine 100 described in paragraph 11, when an external force is detected using a position sensor, the system can switch from servo-off control to zero-speed control in real time, and the rotation angle of the motor, which has been rotated by the external force, can be returned to the rotation angle before the external force occurred. [Explanation of Symbols]

[0134] 10 Clamping device, 11 Bed, 12 Fixed platen, 13 Clamping housing, 14 Movable platen, 15 Tie bar, 16 Clamping mechanism, 17,18 Mold, 19 Ball screw, 20 Injection device, 21 Base, 22 Heating cylinder, 23 Screw, 24 Drive mechanism, 25 Hopper, 26 Injection nozzle, 27 Nozzle touch device, 29A,29C Thermocouple, 30 Control panel, 31 Display, 32 Input device, 40 Control device, 41 Control unit, 41b Memory, 42 Input interface, 43 Output interface, 44 Storage device, 50A~50D Servo amplifier, 80A~80D Servo motor, 81A~81D Current sensor, 84A~84D Position sensor, 100,100A,100B Injection molding machine, 200 Power supply system, 260 DC bus, CV1 converter, IV1 inverter.

Claims

1. First servo motor and A first servo amplifier that supplies power to the first servo motor, The system includes a control device that controls the first servo amplifier to execute a molding cycle, The first servo amplifier includes a first switching element and a second switching element, The molding cycle includes a first period during which the first servo motor is rotated and a second period during which the first servo motor is not rotated. The first servo motor is configured to rotate when controlled by the first control and to stop when controlled by the second control or the third control. The first control is a control that rotates the first servo motor by controlling the first switching element and the second switching element to be turned on in different phases. The third control is a control that controls the first switching element and the second switching element to be turned on in the same phase, thereby stopping the rotation of the first servo motor. The second control is a control that controls the first switching element and the second switching element to the off state, thereby stopping the rotation of the first servo motor. The control device is During the first period, the first control is performed. An injection molding machine that performs the second control or the third control during the second period.

2. The first servo motor is a mold opening / closing motor that opens and closes the mold, The injection molding machine according to claim 1, wherein the control device performs the third control during an injection process in which an injection material is injected into a mold and a holding pressure process in which pressure is maintained to hold the injected injection material inside the mold.

3. The first servo motor is an injection motor that injects the injection material into the mold, The injection molding machine according to claim 1, wherein the control device performs the third control during a holding pressure step, which maintains pressure to hold the injected material in the mold.

4. A second servo motor different from the first servo motor, The injection molding machine according to claim 1, further comprising a second servo amplifier for supplying power to the second servo motor.

5. The first servo motor is a mold opening / closing motor that opens and closes the mold, The aforementioned second servo motor is an ejection motor for removing the molded product from the mold, The injection molding machine according to claim 4, wherein the control device performs the third control on the first servo motor during the period in which the second servo motor is driven.

6. The injection molding machine according to claim 1, further comprising a torque sensor for detecting torque generated in the first servo motor.

7. The control device is A test cycle including a third period during which the first servo motor is rotated and a fourth period during which the first servo motor is not rotated is performed before the molding cycle is executed. During the fourth period, the third control is performed. The injection molding machine according to claim 6, wherein, based on the value detected by the torque sensor during the fourth period, a period during the second period for executing the second control and a period during the second period for executing the third control are determined.

8. The control device is The injection molding machine according to claim 6, wherein if the torque sensor does not detect torque for a predetermined period of time during the execution of the third control, the machine switches from the third control to the second control.

9. The system further includes a speed sensor for detecting the rotational speed of the first servo motor, The control device is The injection molding machine according to any one of claims 1, 6 to 8, wherein if the speed sensor detects a change in rotational speed during the period in which the second control is being performed, the machine switches from the second control to the third control.

10. An angle sensor for detecting the rotation angle of the first servo motor, The system further comprises a storage device for storing the detection results of the angle sensor, The control device is The value detected by the angle sensor when the execution of the second control is started is stored in the storage device. The injection molding machine according to claim 9, wherein when the speed sensor detects a change in rotational speed, the first servo motor is rotated to a rotational angle indicated by the detected value of the angle sensor stored in the storage device.

11. A position sensor that detects the rotational speed and rotational angle of the first servo motor, The system further comprises a storage device for storing the detection results of the position sensor, The control device is During the period in which the second control is being performed, if the position sensor detects a change in rotational speed, the control switches from the second control to the third control. The detected value of the position sensor when the execution of the second control is started is stored in the storage device. The injection molding machine according to any one of claims 1, 6 to 8, wherein when the position sensor detects a change in rotational speed, the first servo motor is rotated to a rotational angle indicated by the detected value of the position sensor stored in the storage device.

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