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] The present disclosure relates to an injection molding machine. [Background technology]

[0002] In a factory, an injection molding machine is used to mold a molded product using a base material such as plastic resin. Patent Document 1 (JP 2020-069756 A) describes an electric injection molding machine having a servo motor. Such an injection molding machine mass-produces molded products by repeatedly executing a molding cycle of an injection molding process including multiple steps such as an injection step and a pressure holding step.

[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 that supplies 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 that is connected to the output side of the PWM converter, and an inverter that is 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] JP 2020-069756 A Summary of the Invention [Problem to be solved by the invention]

[0005] The molding cycle includes a period during which the motor is rotated and a period during which the motor is stopped. During the period during which the motor is stopped, at least one of the switching elements of the inverter may be turned on to control the motor to stop at a predetermined rotation angle. When the motor is stopped by turning on at least one of the switching elements of the inverter, unintentional changes in the rotation angle of the motor due to the occurrence of an external force can be suppressed, but power consumption occurs due to the switching of the switching elements.

[0006] The present disclosure has been made to solve such problems, and its purpose is to suppress an increase in power consumption while preventing the rotation angle of the motor from unintentionally changing due to the occurrence of an external force on the motor. [Means for solving the problem]

[0007] An injection molding machine according to an 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 by being controlled by the first control and to be stopped by being controlled by the second control or the third control. The first control is a control that controls the first switching element and the second switching element to an ON state with different phases to rotate the first servo motor. The second control is a control that controls the first switching element and the second switching element to an ON state with the same phase to stop the rotation of the first servo motor. The third control is a control that controls the first switching element and the second switching element to an OFF state to stop the rotation of the first servo motor. The control device executes a first control in a first period, and executes a second control or a third control in a second period. Effect of the Invention

[0008] According to the injection molding machine of the present disclosure, it is possible to suppress an increase in power consumption while suppressing unintentional changes in the rotation angle of the motor due to the generation of external force on the motor. [Brief description of the drawings]

[0009] [Figure 1] 1 is an external view of an injection molding machine according to a first embodiment. [Diagram 2] 1 is a schematic block diagram of an injection molding machine according to a first embodiment. [Diagram 3] 2 is a diagram showing details of an electric circuit configuration of a servo amplifier according to the first embodiment. FIG. [Figure 4] FIG. 4 is a diagram for explaining the operation of a switching element. [Diagram 5] FIG. 2 is a diagram for explaining a molding cycle in the first embodiment. [Figure 6] FIG. 11 is a schematic block diagram of an injection molding machine according to a second embodiment. [Figure 7] 10 is a flowchart showing a process for determining a zero speed period and a servo-off period. [Figure 8] FIG. 11 is a diagram for explaining a test cycle in the second embodiment. [Figure 9] FIG. 11 is a schematic block diagram of an injection molding machine according to a third embodiment. [Figure 10] 13 is a flowchart showing a process procedure for switching between zero speed control and servo-off control in the third embodiment. [Figure 11] 13 is a flowchart showing a process for switching between zero speed control and servo-off control in the first modification. [Figure 12] 13 is a flow chart showing a processing procedure of an injection molding process in Modification 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 designated by the same reference characters and their description will not be repeated. [Embodiment 1] <Injection molding machine configuration> In the following, an injection molding machine 100 in the first embodiment will be described with reference to Fig. 1. Fig. 1 is an external view of the injection molding machine 100 in the first embodiment.

[0011] The injection molding machine 100 is placed on an XY plane. The direction perpendicular to the XY plane is the Z-axis direction. In the following, the positive direction of the Z axis in FIG. 1 may be referred to as the upper side or upward, and the negative direction as the lower side or downward. Note that although the injection molding machine 100 shown in FIG. 1 is shown as a horizontal injection molding machine, the injection molding machine 100 of the first embodiment is not limited to a horizontal type and may be a vertical injection molding machine.

[0012] The injection molding process performed by the injection molding machine 100 includes a mold closing process, an injection process, a pressure holding process, a mold opening process, a cooling process, an ejection process, and a plasticization process. The injection molding machine 100 repeatedly executes the above-mentioned cycles of the injection molding process. 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 the injection molding process according to the shape and type of material of the molded product.

[0013] The injection molding machine 100 includes a clamping unit 10 that clamps a mold, an injection unit 20 that melts and injects an injection material, an operation panel 30, and control units 40A to 40D. The clamping unit 10 is disposed on the negative side of the X-axis relative to the injection unit 20.

[0014] <Mold clamping device> In the first embodiment, 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 and 18, a ball screw 19, and servo motors 80C and 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 on the bed 11 in the X-axis direction.

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

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

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

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

[0019] After the mold opening process, the injection molding machine 100 performs a process called the "ejection process." The ejection process is a process in which an injection material such as a resin that has been filled in the molds 17, 18 and then solidified is removed from the mold 17. Specifically, the ejection motor 80D rotates to eject a pin (not shown) or the like, thereby removing the molded product that is in close contact with the mold 17. The servo motor 80D provided in the movable platen 14 is a motor used in the ejection process. Hereinafter, the servo motor 80D may be referred to as the "ejection motor 80D."

[0020] <Injection device> The injection device 20 includes 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 disposed on the positive side of the X-axis of the bed 11, and holds the drive mechanism 24 and the like. The servo motors 80A and 80B are provided within the drive mechanism 24.

[0021] The screw 23 is disposed in the heating cylinder 22. The injection molding machine 100 performs a process called the "plasticization process" using the screw 23. The plasticization process is a process in which the resin to be injected is mixed by heating with the heating cylinder 22 and rotating the screw 23. The servo motor 80B in the drive device 24 rotates the screw 23 with the X-axis direction as the central axis. That is, the servo motor 80B is a motor used in the plasticization process. Hereinafter, the servo motor 80B may be referred to as the "plasticization motor 80B."

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

[0023] The hopper 25 is provided on the positive side of the Z axis of the heating cylinder 22. The injection nozzle 26 is provided at the end of the heating cylinder 22 on the negative side of the X axis. 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. The thermocouples 29A to 29C can be disposed near the injection nozzle 26 and near the heating cylinder 22. The thermocouples 29A to 29C are temperature sensors that detect the temperatures at the locations where they are disposed.

[0024] The base 21 includes therein control devices 40A-40D and servo amplifiers 50A-50D. The servo amplifiers 50A-50D supply power to the servo motors 80A-80D, respectively. More specifically, the servo amplifiers 50A-50D generate three-phase AC voltages and supply the three-phase AC power to the corresponding servo motors. The control devices 40A-40D control the servo amplifiers 50A-50D, respectively, to execute a molding cycle. The control devices 40A-40D are electrically connected to each other.

[0025] The operation panel 30 displays information related to the injection molding machine 100 and accepts operations from a user. The operation panel 30 is electrically connected to at least one of the control devices 40A to 40D. In the example of FIG. 1, the operation panel 30 is provided on the negative side of the Y axis of the injection molding machine 100. In a certain aspect, the operation panel 30 may be provided separately from the injection molding machine 100, and may be disposed, for example, in a room different from the room in which the injection molding machine 100 is disposed.

[0026] The operation panel 30 includes a display 31 and an input device 32. The input device 32 includes, for example, a plurality of buttons. In one aspect, the display 31 and the input device 32 may be integrally provided as a touch panel. The operation panel 30 may also include a microphone and a speaker, and may accept operations from the user by voice.

[0027] <Block diagram of injection molding machine> Fig. 2 is a schematic block diagram of injection molding machine 100 in embodiment 1. As shown in Fig. 2, injection molding machine 100 includes control devices 40A-40D, servo amplifiers 50A-50D, and servo motors 80A-80D described in Fig. 1.

[0028] As described in FIG. 1, the servo amplifier 50A and the servo motor 80A are used in the injection process. The servo amplifier 50B and the servo motor 80B are used in the plasticization process. The servo amplifier 50C and the servo motor 80C are used in the mold opening and closing process. The servo amplifier 50D and the servo motor 80D are used in the ejection process. Between the servo amplifiers 50A-50D and the servo motors 80A-80D, respectively, power supply paths for driving the servo motors 80A-80D are shown. In FIG. 1, the power supply system is omitted.

[0029] The internal configuration of the control device 40A will be described below. Note that the control devices 40B to 40C have the same internal configuration as the control device 40A as shown in FIG. 2, and therefore the description of the internal configuration of the control devices 40B to 40C will not be repeated. Also, in the internal configuration of the control devices 40B to 40C, the same or corresponding parts as those in the internal configuration of the control device 40A are denoted by the same reference numerals. The control device 40A includes a control unit 41, an output interface 43, and a storage device 44. The control unit 41 of the control device 40A is connected to the servo amplifier 50A so as to be able to transmit a control signal via the output interface 43. The control unit 41 of the control device 40A transmits a control signal to the servo amplifier 50A to control the state of a switching element, which will be described later.

[0030] The control unit 41 includes a CPU 41a and a memory 41b. The CPU 41a loads a program stored in a read-only memory (ROM) into a random access memory (RAM) and executes the program. The memory 41b includes a ROM and a RAM, and stores the program executed by the CPU 41a.

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

[0032] <Explanation of the electrical circuit> Fig. 3 is a diagram showing details of the electric circuit configuration in the servo amplifier 50A according to the embodiment 1. In Fig. 3, the electric circuit configuration of the servo amplifier 50A will be described as an example, but the servo amplifiers 50B to 50D also have the same electric circuit configuration as the 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 a DC bus 260. The AC / DC converter Cv1 includes a three-phase full-bridge type PWM rectifier.

[0034] The AC / DC converter Cv1 converts the AC power supplied from the system power supply 200 into DC power and supplies the converted DC power to the DC bus 260. The DC bus 260 includes two power supply lines PL1, NL1. The AC / DC converter Cv1 may include a filter circuit for removing high-frequency noise components, a step-up transformer, and the like, but these are omitted from the illustration in the example of Fig. 3 for ease of explanation. A smoothing capacitor is disposed between the power supply lines PL1, NL1 in the DC bus 260.

[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 supply lines PL1 and NL1 of the DC bus 260. Hereinafter, the switching elements U1, U2, V1, V2, W1, and W2 are 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." The switching element U1 may correspond to the "first switching element" in the present disclosure. The switching element V1 may correspond to the "second switching element" in the present disclosure.

[0036] In the inverter Iv1, the switching elements U1, V1, and W1 and the switching elements U2, V2, and W2 are switched in a complementary manner. That is, when the switching element U1 is in an on state, the switching element U2 is in an off state.

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

[0038] 2, the servo amplifier 50A is controlled by the control device 40A of the injection molding machine 100. Specifically, the control device 40A transmits a control signal to each of the switching elements U1-W2 to control the state of each of the switching elements U1-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 applies a gate voltage as a control signal to the control terminals (gate terminals) of the switching elements U1 to W2 to turn on the switching elements U1 to W2. When applying a gate voltage to the switching elements U1 to W2, power consumption occurs. Power is consumed due to losses caused by gate resistance and switch resistance.

[0040] <Switching element operation> FIG. 4 is a diagram for explaining the operation of the 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 be able to execute the motor rotation control, zero speed control, and servo off control shown in FIG. 4. The motor rotation control may correspond to the "first control" in this disclosure. The servo off control may correspond to the "second control" in this disclosure. The zero speed control may correspond to the "third control" in this disclosure. The zero speed control may include a position control to be described later. That is, when the control device 40A detects the rotation of the servo motor during the zero speed control, the control device 40A may return the angle of the servo motor to a predetermined angle.

[0041] The motor rotation control is a control for rotating the servo motor 80A. The control device 40A switches each of the switching elements U1 to W2 at a timing for rotating the servo motor 80A, for example, with 120-degree energization. That is, the motor rotation control is a control for rotating the servo motor 80A by controlling the switching elements U1, V1, and W1 of the upper arm to be in an on state with different phases. When the motor rotation control is performed, the switching elements U1 to W2 generate power consumption due to application of gate voltage and power consumption that is supplied from the system power supply and used to drive the servo motor 80A.

[0042] The zero speed control is a control for stopping the rotation of the servo motor 80A so as to keep the rotation speed of the servo motor 80A at zero. In other words, the zero speed control is a control for stopping the rotation of the servo motor 80A by repeating the on state and the off state of each of the switching elements U1 to W2 in the same phase.

[0043] 4, the control device 40A repeats, in the same phase, a period in which the upper arm is in the OFF state and the lower arm is in the ON state, and a period in which the upper arm is in the ON state and the lower arm is in the OFF state. As a result, the voltage values ​​of the U-phase, V-phase, and W-phase of the servo motor 80A become the same value, and the servo motor 80A stops rotating.

[0044] In the example of the zero speed control in Fig. 4, the switching elements U1 to W2 are repeatedly switched between the on state and the off state, but during the period when the zero speed control is being 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. Also, during the period when the zero speed control is being 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 have to be repeatedly performed.

[0045] During zero speed control, when an external force is generated in the servo motor 80A and the rotation angle of the servo motor 80A changes, at least one of the switching elements U1 to W2 is in the ON state, so that a force that suppresses the change in the rotation angle is generated in the servo motor 80A. This allows the servo motor 80A to stop while maintaining the rotation angle. As shown in Figure 4, when performing zero speed control, a gate voltage is applied to at least one of the switching elements U1 to W2, so power consumption occurs.

[0046] The servo-off control is a control for stopping the rotation of the servo motor 80A without applying any force to the servo motor 80A. As shown in Fig. 4, the control device 40A turns off all of the switching elements U1, V1, and W1. That is, the servo-off control is a control for stopping 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 external force will change the rotation angle of the servo motor 80A. On the other hand, as shown in Fig. 4, when servo-off control is performed, no gate voltage is applied to the switching elements U1 to W2, so no power consumption is generated. In Fig. 4, each control is explained using the control device 40A, but the control devices 40B to 40D are also configured to be able to perform motor rotation control, zero speed control, and servo-off control on the servo amplifiers 50B to 50D.

[0048] <Molding cycle> Fig. 5 is a diagram for explaining the molding cycle in embodiment 1. As described above, the injection molding machine 100 in this embodiment continuously repeats the molding cycle to produce a plurality of molded products. Fig. 5 shows the control of each of the servo motors 80A-80D in one molding cycle.

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

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

[0051] In the mold closing step from timing t0 to t1, the mold opening / closing motor 80C rotates, causing the molds 17 and 18 to come into close contact with each other. After the mold closing step, in the injection step from timing t1 to t2, the injection motor 80A rotates, causing the injection material to be injected into the mold. That is, the screw 23 slides in the negative direction of the X-axis, and injects the injection material into the mold. After the injection step, in the pressure holding step from timing t2 to t3, none of the servo motors 80A to 80D are driven.

[0052] After the dwelling step is completed, in the mold opening step from timing t3 to t4, the mold opening / closing motor 80C rotates to separate the molds 17 and 18. In the plasticizing step from timing t3 to t5, the screw 23 slides in the positive direction of the X-axis due to the rotation of the injection motor 80A. The moving speed of the screw 23 in the plasticizing step is slower than the moving speed of the screw 23 in the injection step, since the purpose is to return the screw 23 to its original position.

[0053] In the plasticizing step, the plasticizing motor 80B rotates the screw 23 with the X-axis direction as the central axis. This kneads the injection material to be used in the next molding cycle. Finally, in the ejection step from timing t5 to t6, the ejection motor 80D rotates to eject a pin (not shown) and the like, thereby removing the molded product that is in close contact with the mold 17.

[0054] 5, the motor rotation period of the injection motor 80A is the period from timing t1 to t2 and the period from timing t3 to t5. The motor rotation period of the plasticization motor 80B is the period from timing t3 to t5. The motor rotation period of the mold opening / closing motor 80C is the period from timing t0 to t1 and the period from timing t3 to t4. The motor rotation period of the ejection motor 80D is the period from timing t5 to t6.

[0055] <Zero speed control and servo off control> In the injection molding machine 100 of the first embodiment, it is determined in advance whether each of the servo motors 80A to 80D executes zero speed control or servo off control during a motor stop period that is not a motor rotation period. Specifically, as shown in Fig. 5, the injection motor 80A executes servo off control during the mold closing process and the ejection process, and executes zero speed control during the pressure holding process. The plasticizing motor 80B executes servo off control during all processes except the plasticizing process.

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

[0057] The pressure holding process is a process in which the screw 23 that has slid to the negative side of the X-axis in the injection process is fixed and pressure is applied to the injection material in the molds 17, 18. During the pressure holding process, a force that pushes the screw 23 back toward the positive side of the X-axis is generated due to a reaction from the injection material to which pressure is being applied. Therefore, in the injection molding machine 100 of the first embodiment, zero speed control is performed on the injection motor 80A in the pressure holding process to prevent the screw 23 from being pushed back toward the positive side of the X-axis and the pressure on the injection material from being lost.

[0058] During the injection process, a reaction occurs from the injection material for the same reason as during the pressure holding process. The reaction of applying pressure to the injection material occurs not only to the screw 23 but also to the molds 17 and 18. Specifically, the injection material to which pressure is applied in the molds 17 and 18 applies a force to the molds 17 and 18 that separates the molds 17 and 18. Therefore, 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 pressure holding process as shown in FIG. 5. As a result, in the injection molding machine 100 in the first embodiment, the positions of the molds 17 and 18 can be maintained against the reaction from the injection material during the injection process and the pressure holding process.

[0059] As shown in FIG. 1, the protruding motor 80D is provided in the movable platen 14. The molded product in close contact with the mold 17 is removed by the pin being protruded by the driving of the protruding motor 80D, but the movable platen 14 may move in the X-axis direction due to the reaction caused by the protruding pin. Therefore, as shown in FIG. 5, in the protruding process driven by the protruding motor 80D, the mold opening / closing motor 80C is subjected to zero speed control. In the first embodiment, an example in which the control devices 40A to 40D control the servo amplifiers 50A to 50D, respectively, has been described, but the servo amplifiers 50A to 50D may be controlled by one control device. That is, the control devices 40A to 40D may not be provided separately from each other, but may be provided as one control device.

[0060] In this way, in the injection molding machine 100 of the first embodiment, the zero speed control is executed only during a period when an external force may be generated for each of the servo motors 80A-80D, and the servo-off control is executed during a period when no external force is generated from other components of the injection molding machine 100. As a result, the period during which all of the switching elements U1-W2 are in the off state becomes longer than when the zero speed control is executed during the entire motor stop period, and power consumption can be reduced. That is, in the injection molding machine 100 of the first embodiment, it is possible to prevent the rotation angle of each of the servo motors 80A-80D from being unintentionally changed due to the external force, and to reduce power consumption and stop the rotation of each of the servo motors 80A-80D.

[0061] <Embodiment 2> In the first embodiment, an example in which the zero speed period and the servo off period in the molding cycle are determined in advance has been described. However, as described above, the motor rotation period in the molding cycle varies depending on 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 the servo off period for each molding condition. In the second embodiment, a method of automatically determining the zero speed period and the servo off period in the molding cycle by performing a test cycle will be described. Note that in the second embodiment, the description of the same configuration as in the first embodiment will not be repeated.

[0062] FIG. 6 is a schematic block diagram of an injection molding machine 100A in the second embodiment. In the injection molding machine 100A, a current sensor is provided for each of the servo motors 80A-80D. In the second embodiment, the servo amplifiers 50A-50D are controlled by one control device 40. In a certain aspect, the injection molding machine 100A in the second embodiment may also be provided with control devices 40A-40D that control the servo amplifiers 50A-50D, respectively, as described in the first embodiment. In that case, the flowchart in FIG. 7, which will be described later, may be executed by any one of the control devices 40A-40D, or another control device that comprehensively controls the control devices 40A-40D. As shown in FIG. 6, the injection molding machine 100A includes current sensors 81A-81D in addition to the control device 40, the servo amplifiers 50A-50D, and the servo motors 80A-80D. In addition to the output interface 43, the control device 40 includes an input interface 42.

[0063] The current sensors 81A-81D detect the motor currents of the servo motors 80A-80D, respectively. The current sensors 81A-81D transmit the detected current values ​​to the control unit 41 via the input interface 42. In the servo motors 80A-80D, the motor currents are correlated with the torques generated in the motors. The storage device 44 stores torque values ​​in association with the current values ​​detected by the current sensors 81A-81D. That is, the control unit 41 can estimate the torques generated in the servo motors 80A-80D based on the detection values ​​of the current sensors 81A-81D. The current sensors 81A-81D may correspond to the "first sensor" in this disclosure.

[0064] <Method of determining zero speed period and servo off period by test cycle> 7 is a flowchart showing a process for determining a zero speed period and a servo-off period. The flowchart shown in FIG.

[0065] In the second embodiment, a test cycle is executed before starting a molding cycle. The test cycle is a trial cycle having the same motor rotation period and motor stop period as the molding cycle. In the second embodiment, the zero speed period and servo off period are determined based on the torque generated during the motor stop period in the test cycle. The control unit 41 executes the flowchart shown in FIG. 7 before executing the molding cycle.

[0066] The control unit 41 executes a test cycle (step S100). The test cycle is a cycle in which zero speed control is performed during the entire motor stop period. FIG. 8 is a diagram for explaining the test cycle in the second embodiment. As shown in FIG. 8, in the test cycle, servo-off control is not executed, and only motor rotation control and zero speed control are performed. The "motor rotation period" shown in FIG. 8 may correspond to the "third period" in the present disclosure. The "zero speed period" shown in FIG. 8 may correspond to the "fourth period" in the present disclosure.

[0067] 7, the control unit 41 determines whether the test cycle has ended (step S110). If the test cycle has not ended (NO in step S110), the control unit 41 repeats the process of step S110. If the test cycle has ended (YES in step S110), the control unit 41 acquires the detection results of the current sensors 81A-81D during the test cycle executed in step S100 (step S120).

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

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

[0070] To explain using a more specific example, in the pressure holding process from timing t2 to timing t3 shown in Fig. 8, if the control unit 41 determines that an external force has been applied to the injection motor 80A from the detection value of the current sensor 81A, the control unit 41 determines the pressure holding 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 Fig. 8, if the control unit 41 determines that no external force has been applied to the injection motor 80A from the detection value of the current sensor 81A, the control unit 41 determines the pressure holding process in the molding cycle as a servo-off period.

[0071] In this way, the control unit 41 determines the zero speed period and servo off period of each servo motor 80A-80D in the molding cycle based on the detection results of the current sensors 81A-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 140). As a result, in the second embodiment, the zero speed period and servo off period in the molding cycle can be determined based on the test cycle for determining whether an external force has actually occurred. Also, in the second embodiment, the user does not need to consider whether an external force has occurred in each period, so the zero speed period and servo off period in the molding cycle can be automatically determined by simply performing the test cycle.

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

[0073] Fig. 9 is a schematic block diagram of an injection molding machine 100B in embodiment 3. In injection molding machine 100B, a position sensor is provided for each of servo motors 80A-80D. Specifically, as shown in Fig. 9, injection molding machine 100B further includes position sensors 84A-84D from the configuration of embodiment 2.

[0074] The position sensors 84A-84D are, for example, optical encoders. The position sensors 84A-84D detect the rotation speeds of the servo motors 80A-80D, respectively. The position sensors 84A-84D also detect the rotation angles of the servo motors 80A-80D, respectively. Note that in one aspect, the position sensors 84A-84D may not be a single optical encoder, but may be provided separately as a speed sensor that detects the rotation speed and an angle sensor that detects the rotation angle.

[0075] The position sensors 84A to 84D transmit the results of their detection to the control unit 41 via the input interface 42. This allows the control unit 41 to obtain the rotation speeds and rotation angles of the servo motors 80A to 80D.

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

[0077] The flowchart shown in Fig. 10 shows a processing procedure for executing one molding cycle. The control unit 41 executes the flowchart shown in Fig. 10 separately for each of the servo motors 80A to 80D. In the third embodiment as well, the motor rotation period is determined in advance according to the molding conditions.

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

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

[0080] After that, the control unit 41 judges again whether or not it is the motor rotation period (step S200). If it is not the motor rotation period (NO in step S200), the control unit 41 performs zero speed control (step S203). For example, when executing the flowchart of FIG. 10 for the mold opening / closing motor 80C, the control unit 41 repeats steps S200, 201, and 202 in the period from timing t0 to t1 in FIG. 5. Since the motor rotation period ends at timing t1, the control unit 41 of the third embodiment performs zero speed control for the mold opening / closing motor 80C (step S203). In the flowchart of FIG. 11, after the zero speed control is executed in step S203, the zero speed control is continuously executed until the motor rotation control or servo-off control is executed or one cycle ends.

[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. Resetting the timer in this embodiment means returning the timer count to an initial value (0 seconds) and starting the count.

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

[0083] When the timer value reaches 100 ms (YES in step S206), the control unit 41 judges whether or not torque has been detected during the 100 ms period measured by the timer from step S204 (step S207). That is, the value detected by the current sensor during the 100 ms period measured by the timer from step S204 is stored in the storage device 44 or memory 41b. The control unit 41 judges whether or not the detection value of the current sensor during the 100 ms period measured by the timer from step S204 is equal to or greater than a predetermined threshold value.

[0084] If torque is detected during the 100 ms period measured by the timer from step S204 (YES in step S207), the control unit 41 determines that an external force occurred during the most recent 100 ms period, and returns the process to step S204. That is, the control unit 41 continues to perform the zero speed control for another 100 ms period.

[0085] In step S207, if no torque is detected in the 100 ms period measured by the timer from step S204 (NO in step S207), the control unit 41 determines that no external force has occurred in the last 100 ms period, and switches from zero speed control to servo-off control (step S208). In the flowchart of Fig. 11, after the servo-off control is executed in step S208, the servo-off control is continued until motor rotation control or zero speed control is performed or one cycle ends.

[0086] That is, since there is a possibility that a period in which no external force is generated will continue in the next 100 ms period since no external force was generated in the most recent 100 ms period, the control unit 41 switches from zero speed control to servo-off control in order to reduce power consumption. That is, the control unit 41 switches from zero speed control to servo-off control when no torque is detected over a period of 100 ms while the zero speed control is being executed.

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

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

[0089] When the timer value reaches 100 ms (YES in step S212), the control unit 41 judges whether or not a rotation speed has been detected in the 100 ms period measured by the timer from step S210 (step S213). That is, it judges whether or not the value of the position sensor in the 100 ms period measured by the timer from step S210 is equal to or greater than a predetermined threshold. In step S213, unlike step S207, the control unit 41 performs servo-off control. Therefore, when an external force is generated on the servo motor, the servo motor rotates due to the external force, and a rotation speed is generated.

[0090] When the control unit 41 detects the rotation speed during the period of 100 ms measured by the timer from step S210 (YES in step S214), it controls the position of the servo motor to the position of the rotation angle acquired in step S208 (step S214). This allows the control unit 41 to return the rotation angle of the servo motor that has rotated due to an external force to the rotation angle before the external force was generated.

[0091] The control unit 41 determines that an external force occurred in the most recent 100 ms period and switches from servo-off control to zero speed control (step S203). That is, since an external force occurred in the most recent 100 ms period, there is a possibility that an external force will occur in the next 100 ms period, and therefore the control unit 41 switches from servo-off control to zero speed control in order to fix and stop the servo motor.

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

[0093] Although not shown in Fig. 10, the control unit 41 determines whether or not one cycle has ended in addition to whether it is the motor rotation period in steps S205 and 211. When it is determined that one cycle has ended in steps S205 and 211, the control unit 41 ends the process.

[0094] In this way, in the injection molding machine 100 of the third embodiment, the zero speed period and the servo-off period are not determined in advance by the test cycle or the user, but the external force generated in the servo-off period is detected by detecting the rotation speed, and the control is switched from the servo-off control to the zero speed control in real time. As a result, in the injection molding machine 100 of the third embodiment, the control device 40A to 40D that controls each of the servo amplifiers 50A to 50D may be provided in the third embodiment as well. In that case, the flowchart of FIG. 10 may be executed by any one of the control devices 40A to 40D, or another control device that controls the control devices 40A to 40D in an integrated manner.

[0095] <Variation 1> In the second embodiment, the zero speed period and the servo-off period are determined based on the test cycle, and in the third embodiment, the zero speed control and the servo-off control are switched based on the position sensors 84A to 84D. In the first modification, a configuration in which the second embodiment and the third embodiment are combined will be described.

[0096] The injection molding machine 100 of the first modification has the same configuration as that of the third embodiment shown in Fig. 9. That is, the injection molding machine 100 of the first modification has position sensors 84A-84D. In the injection molding machine 100 of the first modification, the flowchart showing the processing procedure of the test cycle described in Fig. 7 is executed. Thereby, the zero speed period and the servo-off period in the motor stop period are determined.

[0097] The injection molding machine 100 of the first modification preferentially follows 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. Fig. 11 is a flowchart showing a process procedure for switching between zero speed control and servo-off control in the first modification.

[0098] The flowchart in Fig. 11 has a configuration in which step S300 is added to the flowchart in Fig. 10. If it is not a motor rotation period (NO in step S200), the control unit 41 judges whether it is a zero speed period determined in S130 or not (step S300). In other words, if it is a motor stop period, the control unit 41 judges whether it is a zero speed period or a servo off period based on the test cycle.

[0099] If it is the zero speed period (YES in step S300), the control unit 41 performs zero speed control (step S203). Thereafter, 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 the zero speed period (NO in step S300), the control unit 41 performs servo-off control (step S208). Thereafter, 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] In this way, the injection molding machine 100 of variant example 1 automatically determines the zero speed period and servo off period using a test cycle, and can appropriately switch between zero speed control and servo off control in real time even when a sudden external force such as an earthquake, accident, or failure of a component that constitutes the injection molding machine 100 occurs.

[0101] <Variation 2> In the second embodiment, an example has been described in which the zero speed period and the servo-off period are determined in all molding cycles executed in the injection molding process based on the test cycle. In the second modification, an example will be described in which the zero speed period and the servo-off period are updated for each cycle.

[0102] The injection molding machine 100 of the modified example 2 has a similar configuration to that of the embodiment 3 shown in Fig. 9. Fig. 12 is a flow diagram showing the procedure of the injection molding process in the modified example 2. In the modified example 2, as in the embodiment 2, a test cycle is executed before starting a molding cycle.

[0103] The test cycle in the second modification is a trial 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 the second modification is a cycle in which zero speed control is performed during the entire motor stop period, as in the second embodiment.

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

[0105] 12, when step S420 is executed for the first time, the most recent cycle is the test cycle executed in step S400. As described above, the servo-off control is not performed in the test cycle. Therefore, in step S420, the control unit 41 determines whether or not an external force has occurred based on the detection value of 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 detection values ​​of the current sensor and the position sensor (step SS430). That is, the control unit 41 determines a specific period in which an external force is generated as the zero speed period, and determines a specific period in which an external force is not generated as the servo-off period.

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

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

[0109] At this time, the control unit 41 determines the zero speed period and the servo-off period in the next cycle based on the specific period during which the external force occurred during the new cycle executed in step S440, not the test cycle. When the injection molding process is completed (YES in step S460), the control unit 41 ends the process.

[0110] In this way, the injection molding machine 100 of the modified example 2 updates the zero speed period and the servo-off period for each cycle, which allows the injection molding machine 100 of the modified example 2 to determine the zero speed period and the servo-off period based on the latest data.

[0111] [Note] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0112] (Item 1) The injection molding machine 100 in the present disclosure includes 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. The servo amplifier 50A includes a first switching element U1 and a second switching element V1. The molding cycle includes a motor rotation period in which the servo motor 80A rotates, and a motor stop period in which the servo motor 80A does not rotate. The servo motor 80A is configured to rotate by being controlled by the motor rotation control, and to be stopped by being controlled by the servo off control or the zero speed control. The motor rotation control is a control that controls the switching element U1 and the switching element V1 to be in an on state with different phases, thereby rotating the servo motor 80A. The servo off control is a control that controls the switching element U1 and the switching element V1 to be in an on state with the same phase, thereby stopping the rotation of the servo motor 80A. The zero speed control is a control in which the switching element U1 and the switching element V1 are controlled to the off state to stop the rotation of the servo motor 80A. The control device 40 executes the motor rotation control during the motor rotation period, and executes the servo off control or the zero speed control during the motor stop period.

[0113] According to the injection molding machine 100 described in the first aspect, it is possible to prevent the rotation angle of the motor from unintentionally changing due to an external force being applied to the motor, reduce power consumption, and stop the motor.

[0114] (2) The servo motor 80C according to the first paragraph is a mold opening / closing motor for opening and closing the mold. The control device 40 executes zero speed control during an injection process for injecting an injection material into the mold and a pressure dwell process for maintaining pressure to hold the injected injection material in the mold.

[0115] According to the injection molding machine 100 described in the second aspect, the pressure applied to the injected material can be maintained.

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

[0117] According to the injection molding machine 100 described in the third aspect, the pressure applied to the injected material can be maintained.

[0118] (4) In any one of paragraphs 1 to 3, the motor controller further includes 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 the fourth aspect, the injection molding process can be performed by a plurality of servo motors.

[0120] (Item 5) In item 4, servo motor 80C is a mold opening / closing motor that opens and closes molds 17 and 18. Servo motor 80D is an ejection motor that removes a molded product from the mold. Control device 40 executes zero speed control on servo motor 80C during the period in which servo motor 80D is driven.

[0121] According to the injection molding machine 100 described in the fifth aspect, it is possible to prevent the movable platen 14 from moving unintentionally due to the driving of the protruding motor.

[0122] (Item 6) In the item 1, a current sensor 81A is further provided that detects torque generated in the servo motor 80A.

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

[0124] (Clause 7) In clause 6, the control device 40 executes a test cycle including a motor drive period in which the servo motor 80A is rotated and a motor stop period in which the servo motor 80A is not rotated before executing a molding cycle, executes zero speed control during the motor stop period (S100), and determines a period in which servo off control is executed during the motor rotation period and a period in which zero speed control is executed during the motor rotation period based on the detection value of the current sensor during the motor stop period (S130).

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

[0126] (Item 8) In item 6 or 7, when the control device 40 is executing zero speed control, if the current sensor does not detect torque for a predetermined period (e.g., 100 ms) (NO in S207), the control device 40 switches from zero speed control to servo-off control (S208).

[0127] According to the injection molding machine 100 described in the eighth aspect, when no external force is detected for a predetermined period of time, the control can be switched from the zero speed control to the servo-off control in real time.

[0128] (Item 9) In any one of items 1, 6 to 8, the injection molding machine 100 further includes a speed sensor that detects the rotation speed of the servo motor 80A. When the speed sensor detects the rotation speed during the period in which the servo-off control is being executed (YES in S213), the control device 40 switches from the servo-off control to the 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] (Item 10) In item 9, the injection molding machine 100 further includes an angle sensor that detects the rotation angle of the servo motor 80A, and a storage device 44 that stores the detection result of the angle sensor. The control device 40 stores the detection value of the angle sensor when the servo-off control is executed in the storage device 44 (S209), and when the speed sensor detects the rotation speed (YES in S213), rotates the servo motor 80A to the rotation angle indicated by the detection value of the angle sensor stored in the storage device 44 (S214).

[0131] According to the injection molding machine 100 described in the tenth aspect, the rotation angle of the motor that has been rotated by an external force can be returned to the rotation angle before the external force was generated.

[0132] (Item 11) In any one of items 1, 6 to 8, the control device 40 further includes a position sensor 84A that detects the rotation speed and rotation angle of the servo motor 80A. When the position sensor 84A detects the rotation speed during the period in which the second control is being executed, the control device 40 switches from the second control to the third control and stores in the memory device 44 the detection value of the position sensor 84A when the second control is being executed, and when the position sensor 84A detects the rotation speed, the control device 40 rotates the servo motor 80A to the rotation angle indicated by the detection value of the position sensor 84A stored in the memory 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 control is switched from servo-off control to zero speed control in real time, and the rotation angle of the motor that has rotated due to an external force can be returned to the rotation angle before the external force was generated. [Explanation of symbols]

[0134] 10 mold clamping unit, 11 bed, 12 fixed platen, 13 mold clamping housing, 14 movable platen, 15 tie bar, 16 mold clamping mechanism, 17, 18 mold, 19 ball screw, 20 injection unit, 21 base, 22 heating cylinder, 23 screw, 24 drive mechanism, 25 hopper, 26 injection nozzle, 27 nozzle touch device, 29A, 29C thermocouple, 30 operation panel, 31 display, 32 input device, 40 control device, 41 control unit, 41b memory, 42 input interface, 43 output interface, 44 storage device, 50A to 50D servo amplifier, 80A to 80D servo motor, 81A to 81D current sensor, 84A to 84D position sensor, 100, 100A, 100B injection molding machine, 200 system power supply, 260 DC bus, Cv1 converter, Iv1 inverter.

Claims

1. a first servo motor; a first servo amplifier that supplies power to the first servo motor; 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 by being controlled by a first control and to be stopped by being controlled by a second control or a third control; the first control is a control for rotating the first servo motor by controlling the first switching element and the second switching element to an on state in different phases; the third control is a control for controlling the first switching element and the second switching element to an ON state in the same phase to stop rotation of the first servo motor, the second control is a control for controlling the first switching element and the second switching element to an OFF state and stopping rotation of the first servo motor, The control device The first control is executed during the first period; The injection molding machine executes 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 a mold, 2. The injection molding machine according to claim 1, wherein the control device executes the third control during an injection process of injecting the injection material into the mold and a dwell process of maintaining pressure to hold the injected injection material in the mold.

3. the first servo motor is an injection motor that injects an injection material into a mold, 2. The injection molding machine according to claim 1, wherein the control device executes the third control during a pressure-holding step in which pressure is maintained to hold the injected injection material within 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 that supplies power to the second servo motor.

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

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

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

8. The control device 7. The injection molding machine according to claim 6, wherein the third control is switched to the second control when the torque sensor does not detect torque for a predetermined period of time while the third control is being executed.

9. a speed sensor for detecting a rotation speed of the first servo motor; The control device 9. The injection molding machine according to claim 1, wherein, when the speed sensor detects a change in rotation speed during a period in which the second control is being executed, the injection molding machine switches from the second control to the third control.

10. an angle sensor for detecting a rotation angle of the first servo motor; a storage device that stores the detection result of the angle sensor; The control device storing the detected value of the angle sensor when execution of the second control is started in the storage device; 10. The injection molding machine according to claim 9, wherein, when the speed sensor detects a change in rotation speed, the first servo motor is rotated to a rotation angle indicated by the detection value of the angle sensor stored in the storage device.

11. a position sensor for detecting a rotation speed and a rotation angle of the first servo motor; a storage device that stores the detection result of the position sensor; The control device When the position sensor detects a change in rotation speed during the period in which the second control is being performed, the second control is switched to the third control; storing the detected value of the position sensor when execution of the second control is started in the storage device; 9. The injection molding machine according to claim 1, wherein, when the position sensor detects a change in rotation speed, the first servo motor is rotated to a rotation angle indicated by the detection value of the position sensor stored in the storage device.

Images