Control device for injection device, injection molding system, and method for controlling injection device

Abstract

This control device for an injection device comprises: a first motor control unit that presses, with a force which is smaller than attaching force generated between an injection cylinder and a support part which is connected to an injection member, the support part against the injection cylinder; a second motor control unit that carries out control so that the support part retracts with a force smaller than the attaching force after the pressing; a third motor control unit that stops drive of an injection motor after the retracting; and a zero point correction unit that corrects a zero point of a pressure sensor, which detects pressure applied to the support part, so that the detection value in a state in which the injection motor is stopped becomes zero.

Description

Injection unit control device, injection molding system, and injection unit control method

[0001] The present disclosure relates to a control device for an injection device, an injection molding system, and a control method for an injection device.

[0002] Japanese Patent Laid-Open Publication No. 9-117946 discloses a method for correcting the zero point of a pressure sensor (load cell) provided in an injection unit of an injection molding machine.

[0003] There is a need for a better injection unit control device, injection molding system, and injection unit control method for correcting the zero point of the pressure sensor.

[0004] a support part connected to a rear end of the injection member and supporting the injection member; an injection motor that applies a driving force to the support part to move the injection member; and a pressure sensor that detects a pressure applied to the support part, the control device including: a first motor control part that controls the injection motor so that the injection member and the support part move forward with a limited torque, thereby bringing the support part into contact with and pressing the injection cylinder; a second motor control part that controls the injection motor so that the injection member and the support part move backward with the limited torque after control by the first motor control part; and a pressure sensor that controls the injection motor so that the injection member and the support part move backward with the limited torque after control by the second motor control part. and a zero point correction unit that corrects a zero point of the pressure sensor so that a detection value detected based on the pressure sensor becomes zero in a state in which the drive of the injection motor is stopped by the third motor control unit, wherein when the injection member and the support unit move forward and the support unit comes into contact with the injection cylinder, an adhesive force is generated between the support unit and the injection cylinder, and a force of the support unit moving due to the limit torque is smaller than the adhesive force.

[0005] A second aspect of the present disclosure is an injection molding system including the control device for the injection device and the injection device.

[0006] A third aspect of the present disclosure is a control method for an injection device including an injection cylinder, an injection member inserted into the injection cylinder and movable within the injection cylinder, a support part connected to a rear end of the injection member and supporting the injection member, an injection motor that applies a driving force to the support part to move the injection member, and a pressure sensor that detects a pressure applied to the support part, the control method including: a first motor control step of controlling the injection motor so that the injection member and the support part move forward with a limited torque to bring the support part into contact with and press against the injection cylinder; a second motor control step of controlling the injection motor after the first motor control step so that the injection member and the support part move backward with the limited torque; and a second motor control step of controlling the injection motor after the second motor control step to detect a pressure applied to the support part. a third motor control step of stopping driving of the injection motor in a state where the rotational position of the injection motor is within a range between a first rotational position of the injection motor in a state where the support part is pressed against the injection cylinder and a second rotational position of the injection motor in a state where the second motor control step is performed; and a zero point correction step of correcting a zero point of the pressure sensor so that a detection value detected based on the pressure sensor becomes zero in a state where the drive of the injection motor is stopped by the third motor control step, wherein when the injection member and the support part move forward and the support part comes into contact with the injection cylinder, an adhesive force is generated between the support part and the injection cylinder, and a force of the support part moving due to the limit torque is smaller than the adhesive force.

[0007] FIG. 1 is an overall configuration diagram of an injection molding system according to one embodiment. FIG. 2 is a schematic diagram showing the configuration of an injection device. FIG. 3 is a block diagram of a control device. FIG. 4 is a schematic diagram showing an injection cylinder and a support part in contact with each other. FIG. 5 is a number line illustrating a first rotation position, a second rotation position, and a third rotation position. FIG. 6 is a flowchart illustrating a control method of the injection device. FIG. 7 is a schematic diagram showing the configuration of an injection device according to Modification 2.

[0008] If injection molding is performed with the zero point of the pressure sensor installed in the injection unit deviated, it will have a negative impact on the quality of the molded product. Therefore, it is preferable to appropriately correct the zero point of the pressure sensor. Furthermore, the shorter the time required to correct the zero point of the pressure sensor, the better.

[0009] Based on the above preliminary explanation, one embodiment will be described below.

[0010] FIG. 1 is a diagram showing the overall configuration of an injection molding system SYS according to this embodiment.

[0011] The injection molding system SYS includes an injection molding machine 10 and a control device 12 .

[0012] The injection molding machine 10 is a machine that performs injection molding using a mold 20 to form a molded product. The injection molding machine 10 includes a mold clamping device 14, an injection device 16, and a machine base 18.

[0013] The mold clamping device 14 is a device that applies a mold clamping force to the mold 20. The mold clamping device 14 is arranged on a machine base 18. The mold clamping device 14 opens and closes the mold 20. The mold clamping device 14 applies a mold clamping force to the mold 20 so that the mold 20 does not open. The mold 20 forms a cavity 20c in a closed state. The mold 20 shown in FIG. 1 is in a closed state. A more detailed description of the mold clamping device 14 will be omitted.

[0014] The injection device 16 is a device that plasticizes the molding material and injects the plasticized molding material into the cavity 20c of the mold 20. The injection device 16 is disposed on a machine base 18. The injection molding machine 10 produces a molded product by solidifying the molding material filled into the cavity 20c by the injection device 16. The molding material is, for example, a resin. Note that the injection device 16 is shown schematically in FIG. 1. A more detailed configuration of the injection device 16 is shown in FIG. 2.

[0015] 1 corresponds to the direction in which the mold clamping unit 14 and the injection unit 16 are arranged on the machine base 18. The front-rear direction D includes a front direction D1 and a rear direction D2. In this embodiment, the front direction D1 is the direction from the injection unit 16 toward the mold clamping unit 14. The rear direction D2 is the opposite direction to the front direction D1.

[0016] FIG. 2 is a schematic diagram showing the configuration of the injection device 16.

[0017] The injection device 16 includes an injection cylinder 22 , an injection member 24 , a front plate 26 , a rear plate 28 , a pusher plate 30 , and a slide mechanism 32 .

[0018] The injection cylinder 22 is a cylindrical member. The axis LA of the injection cylinder 22 is parallel to the front-rear direction D. The axis LA coincides with the axis of the injection member 24, which will be described later.

[0019] A nozzle 34 is provided at the front end 22a of the injection cylinder 22. The nozzle 34 has an injection port 34p. The injection port 34p is an opening for injecting the molding material in the injection cylinder 22 into the cavity 20c.

[0020] The injection cylinder 22 is also provided with a hopper 36. The hopper 36 is provided at a relatively rear portion of the injection cylinder 22. The hopper 36 stores molding material. The hopper 36 also supplies the stored molding material into the injection cylinder 22.

[0021] The injection member 24 is a member that is inserted into the injection cylinder 22 and moves within the injection cylinder 22 in the front-to-rear direction D to inject molding material into the cavity 20c (see FIG. 1) of the mold 20. More specifically, the injection member 24 is, for example, a screw 24A or a plunger. In this embodiment, a case will be described in which the injection member 24 is a screw 24A.

[0022] The screw 24A has a front end 24a, a body 24b, and a rear end 24c. The front end 24a is provided with a screw head. The body 24b is provided with a spiral flight formed along the front-to-rear direction D. By providing the flight, the screw 24A can shear the molding material in the injection cylinder 22 in response to the rotation of the screw 24A by the first drive unit 50 described below. The flight may be a single flight or a double flight. The rear end 24c of the screw 24A protrudes from the rear end 22b of the injection cylinder 22.

[0023] The front plate 26 is a member that supports the injection cylinder 22. The injection cylinder 22 passes through the front plate 26. A rear end 24c of the screw 24A is located rearward of the front plate 26.

[0024] The rear plate 28 is located behind the front plate 26. A predetermined gap is provided between the rear plate 28 and the front plate 26.

[0025] The pusher plate 30 is provided between the front plate 26 and the rear plate 28 .

[0026] The slide mechanism 32 includes a rail 38 and a slider 40. The rail 38 extends in the front-rear direction D. The slider 40 is movable along the rail 38. The slider 40 supports the pusher plate 30. Therefore, the pusher plate 30 is movable along the rail 38.

[0027] The front plate 26, the rear plate 28, and the slide mechanism 32 are provided on a flat base 42. The front plate 26, the rear plate 28, and the base 42 may be integrally molded.

[0028] The injection unit 16 includes a support 44 , a screw sleeve 46 , a pressure sensor 48 , a first drive unit 50 , and a second drive unit 52 .

[0029] The support portion 44 supports the rear end portion 24c of the injection member 24. The support portion 44 is, for example, a spline bushing. In this case, the rear end portion 24c of the injection member 24 has a male spline (not shown). In contrast, the support portion 44 has a female spline (not shown). The male spline of the rear end portion 24c and the female spline of the support portion 44 fit together, allowing the support portion 44 to support the rear end portion 24c of the injection member 24.

[0030] The screw sleeve 46 is provided between the pusher plate 30 and the support portion 44. The screw sleeve 46 rotatably supports the support portion 44. The screw sleeve 46 also limits the relative movement of the support portion 44 with respect to the screw sleeve 46 in the front-rear direction D. The screw sleeve 46 has, for example, a bearing member (not shown). The bearing member limits the relative movement of the support portion 44 in the front-rear direction D while rotatably supporting the support portion 44 with respect to the screw sleeve 46.

[0031] The pressure sensor 48 is provided to detect the pressure of molding material such as resin inside the injection cylinder 22. This pressure is the pressure applied to the support part 44 via the injection member 24. The pressure sensor 48 is, for example, a load cell. The pressure sensor 48 is provided, for example, inside the screw sleeve 46. The installation location of the pressure sensor 48 may be changed as appropriate.

[0032] The first driving device 50 is a device that rotates the injection member 24 about the axis LA. The first driving device 50 includes a rotation motor 54, a first driving pulley 56, a first belt 58, and a first driven pulley 60.

[0033] The rotation motor 54 is, for example, an electric servo motor. The rotation motor 54 includes a shaft 54 ​​a. The shaft 54 ​​a rotates when a current is supplied to the rotation motor 54. The shaft 54 ​​a is connected to a first drive pulley 56.

[0034] The first drive pulley 56 rotates in response to the rotation of the shaft 54 ​​a. The first belt 58 is wound around the first drive pulley 56 and the first driven pulley 60. The first belt 58 transmits the rotation of the first drive pulley 56 to the first driven pulley 60.

[0035] The first driven pulley 60 rotates in response to the rotation of the first drive pulley 56 transmitted via the first belt 58. That is, the first driven pulley 60 rotates in response to the rotation of the shaft 54a. The first driven pulley 60 is provided, for example, inside the pusher plate 30. The first driven pulley 60 is connected to the support portion 44. The first driven pulley 60 and the support portion 44 rotate integrally.

[0036] As described above, the rotation of the shaft 54a rotates the support portion 44. The rotation of the support portion 44 rotates the injection member 24. In this manner, the first drive device 50 can rotate the injection member 24 about the axis line LA.

[0037] The second drive device 52 is a device that moves the injection member 24 in the front-rear direction D. The second drive device 52 includes an injection motor 62, a second drive pulley 64, a second belt 66, a second driven pulley 68, a ball screw 70, and a nut 72.

[0038] The injection motor 62 is, for example, an electric servo motor. The injection motor 62 includes a shaft 62a and a rotational position sensor 62b. The shaft 62a rotates when a current is supplied to the injection motor 62. The shaft 62a is connected to a second drive pulley 64. The rotational position sensor 62b detects the rotational position of the shaft 62a. The rotational position sensor 62b is, for example, a rotary encoder.

[0039] The second drive pulley 64 rotates in response to the rotation of the shaft 62a. The second belt 66 is wound around the second drive pulley 64 and the second driven pulley 68. The second belt 66 transmits the rotation of the second drive pulley 64 to the second driven pulley 68.

[0040] The second driven pulley 68 rotates in response to the rotation of the second drive pulley 64 transmitted via the second belt 66. In other words, the second driven pulley 68 rotates in response to the rotation of the shaft 62a.

[0041] The axis of the ball screw 70 is parallel to the front-rear direction D. The ball screw 70 passes through the rear plate 28. The rear plate 28 supports the ball screw 70 rotatably.

[0042] The ball screw 70 is connected to the second driven pulley 68. The ball screw 70 rotates integrally with the second driven pulley 68. Therefore, the ball screw 70 rotates in response to the rotation of the shaft 62a.

[0043] The nut 72 is provided on the rear side of the pusher plate 30. The pusher plate 30 rotatably supports the nut 72. More specifically, the pusher plate 30 rotatably supports the nut 72 using a bearing member (not shown) provided in the pusher plate 30.

[0044] The nut 72 is threaded onto the ball screw 70. The nut 72 moves in the axial direction of the ball screw 70 in response to the rotation of the ball screw 70. That is, the nut 72 moves in the front-to-rear direction D in response to the rotation of the shaft 62a. When the nut 72 moves in the front direction D1, the pusher plate 30 moves in the front direction D1 together with the nut 72. When the nut 72 moves in the rear direction D2, the pusher plate 30 moves in the rear direction D2 together with the nut 72. Because the slide mechanism 32 supports the pusher plate 30, the pusher plate 30 can move smoothly in the front-to-rear direction D.

[0045] When the pusher plate 30 moves in the forward direction D1, the pusher plate 30 pushes the injection member 24 in the forward direction D1 via the screw sleeve 46 and the support portion 44. When the pusher plate 30 moves in the rearward direction D2, the pusher plate 30 pulls the injection member 24 in the rearward direction D2 via the screw sleeve 46 and the support portion 44.

[0046] The injection member 24 moves in the forward direction D1 or the backward direction D2 within the injection cylinder 22 in accordance with the force received from the pusher plate 30. In other words, the injection member 24 is movable along the forward and backward direction D.

[0047] The rotation direction of the shaft 62a when moving the injection member 24 in the forward direction D1 is opposite to the rotation direction of the shaft 62a when moving the injection member 24 in the rearward direction D2. The rotation direction of the shaft 62a when moving the injection member 24 in the forward direction D1 is also referred to as the first rotation direction in the following description. The rotation direction of the shaft 62a when moving the injection member 24 in the rearward direction D2 is also referred to as the second rotation direction in the following description.

[0048] The amount of movement of the injection member 24 correlates with the amount of rotation of the shaft 62a. For example, the amount of movement of the injection member 24 in the forward direction D1 correlates with the amount of rotation of the shaft 62a in a first rotational direction. Similarly, the amount of movement of the injection member 24 in the rearward direction D2 correlates with the amount of rotation of the shaft 62a in a second rotational direction. Because the amount of movement of the injection member 24 correlates with the amount of rotation of the shaft 62a, the rotational position of the shaft 62a detected by the rotational position sensor 62b substantially indicates the position of the injection member 24 in the forward / rearward direction D.

[0049] The origin of the position of the injection member 24 in the front-rear direction D is determined in advance. For example, FIG. 2 shows the distance X in the front-rear direction D between the front end 44a of the support portion 44 and the rear end 22b of the injection cylinder 22. The position of the injection member 24 when the distance X is 1 mm (millimeter) is determined in advance as the origin. However, the method for determining the origin is not limited to this.

[0050] The injection device 16 further includes an attraction member 98. The attraction member 98 is a member for generating an attraction force between the injection cylinder 22 (rear end 22 b) and the support portion 44. The attraction member 98 includes, for example, a magnet (electromagnet 98A) provided on at least one of the rear end 22 b of the injection cylinder 22 and the support portion 44. In this embodiment, a case will be described in which the electromagnet 98A is provided on the support portion 44 and the injection cylinder 22 (rear end 22 b) contains a metal.

[0051] FIG. 3 is a block diagram of the control device 12.

[0052] The control device 12 is a computer that controls at least the injection device 16 of the injection molding machine 10. The control device 12 is, for example, a numerical control device. The control device 12 includes a display unit 74, an operation unit 76, a storage unit 78, and a calculation unit 80.

[0053] The operation unit 76 includes, for example, an operation panel (not shown). The operation panel includes, for example, but is not limited to, a keyboard, a pointing device, etc. The operation unit 76 accepts input operations performed by an operator. The display unit 74 includes a display element (not shown). The display element is a liquid crystal display element, an organic electroluminescence display element, etc. The operation unit 76 and the display unit 74 may be configured by a touch panel (not shown) equipped with such a display element.

[0054] The storage unit 78 includes, for example, one or more memories. More specifically, the storage unit 78 includes, for example, nonvolatile memory such as a read-only memory (ROM), a flash memory, or a magnetic disk, and volatile memory such as a random access memory (RAM). The nonvolatile memory stores, for example, computer-executable programs. The volatile memory stores, for example, data temporarily required when a processor (calculation unit 80) described below performs calculations based on the programs. At least a portion of the storage unit 78 may be realized by a portable storage medium such as a universal serial bus (USB) memory or a memory card.

[0055] The storage unit 78 stores limit torque information 82. The limit torque information 82 is information indicating the magnitude of the limit torque. The limit torque is a designated value of the torque of the shaft 62a (injection motor 62). The limit torque is determined in advance, for example, based on experiments, so that the force in the front-rear direction D that moves the injection member 24 is smaller than the above-mentioned adhesive force between the injection cylinder 22 and the support portion 44.

[0056] The calculation unit 80 includes a predetermined processing circuitry. This processing circuitry includes one or more processors, such as a central processing unit (CPU) or a graphics processing unit (GPU). The processing circuitry may include a predetermined integrated circuit, such as an application specific integrated circuit (ASIC) or a field-programmable gate array (FPGA).

[0057] The calculation unit 80 includes a pressure acquisition unit 84, a rotational position acquisition unit 86, an electromagnet control unit 88, a first motor control unit 90, a second motor control unit 92, a third motor control unit 94, and a zero point correction unit 96. The pressure acquisition unit 84, the rotational position acquisition unit 86, the electromagnet control unit 88, the first motor control unit 90, the second motor control unit 92, the third motor control unit 94, and the zero point correction unit 96 are realized by the calculation unit 80 (processor) executing a program stored in the storage unit 78 (memory). At least some of the pressure acquisition unit 84, the rotational position acquisition unit 86, the electromagnet control unit 88, the first motor control unit 90, the second motor control unit 92, the third motor control unit 94, and the zero point correction unit 96 may be realized by the integrated circuit or the like described above.

[0058] The pressure acquisition unit 84 acquires information indicating the pressure applied to the support unit 44. As described above, the pressure applied to the support unit 44 is detected by the pressure sensor 48. Therefore, the pressure acquisition unit 84 can acquire information indicating the pressure applied to the support unit 44 based on the detection signal of the pressure sensor 48.

[0059] The rotational position acquisition unit 86 acquires information indicating the rotational position of the injection motor 62. As described above, the rotational position of the injection motor 62 (shaft 62 a) is detected by the rotational position sensor 62 b. Therefore, the rotational position acquisition unit 86 can acquire information indicating the rotational position of the injection motor 62 based on the detection by the rotational position sensor 62 b.

[0060] The electromagnet control unit 88 supplies power to the electromagnet 98A described above to generate an attractive force (magnetic force) between the injection cylinder 22 and the support unit 44 .

[0061] The first motor control unit 90 executes the first motor control described below. That is, the first motor control unit 90 controls the injection motor 62 so that the injection member 24 and the support unit 44 move forward, thereby contacting and pressing the support unit 44 against the injection cylinder 22. While the support unit 44 is pressed against the injection cylinder 22, the first motor control unit 90 limits the magnitude of the first torque, which is the torque of the injection motor 62 in the first rotation direction, to the magnitude of the limit torque described above. That is, while the support unit 44 is pressed against the injection cylinder 22, the first motor control unit 90 allows the magnitude of the first torque to increase within a range less than the magnitude of the limit torque, but does not allow the magnitude of the first torque to exceed the magnitude of the limit torque. Note that, as described above, the first rotation direction is the rotation direction of the shaft 62a when moving the injection member 24 in the forward direction D1.

[0062] FIG. 4 is a schematic diagram showing the injection cylinder 22 and the support portion 44 in contact with each other.

[0063] In the following description, the rotational position of the injection motor 62 when the magnitude of the first torque is the limit torque with the support part 44 pressed against the injection cylinder 22 is also referred to as a first rotational position P1. When the first motor control is executed, the rotational position acquisition part 86 can acquire information indicating the first rotational position P1 based on the detection result of the rotational position sensor 62b.

[0064] After the control by the first motor control unit 90, the second motor control unit 92 executes the second motor control described below. That is, after the control by the first motor control unit 90, the second motor control unit 92 controls the injection motor 62 so that the injection member 24 and the support unit 44 move backward. In this case, the second motor control unit 92 limits the magnitude of the second torque, which is the torque of the injection motor 62 in the second rotation direction, to the magnitude of the limit torque described above. That is, the second motor control unit 92 allows the magnitude of the second torque to increase within a range less than the magnitude of the limit torque, but does not allow the magnitude of the second torque to exceed the magnitude of the limit torque. Note that, as described above, the second rotation direction is the rotation direction of the shaft 62a when moving the injection member 24 in the rearward direction D2.

[0065] As described above, an attractive force is generated between the injection cylinder 22 and the support portion 44. Also, as described above, the limit torque is determined so that the force that moves the injection member 24 and the support portion 44 in the front-rear direction D is smaller than the attractive force. Therefore, while the second motor control is being performed, the injection member 24 and the support portion 44 are pulled in the rear direction D2, but the attraction between the injection cylinder 22 and the support portion 44 is not released. Therefore, while the second motor control is being performed, the injection member 24 and the support portion 44 cannot move backward.

[0066] In the following description, the rotational position of the injection motor 62 when the second motor control is being performed and the magnitude of the second torque is the magnitude of the limit torque is also referred to as the second rotational position P2. When the second motor control is being performed, the rotational position acquisition unit 86 can acquire information indicating the second rotational position P2 based on the detection result of the rotational position sensor 62b.

[0067] According to this embodiment, the support portion 44 does not move in the forward / backward direction D when the first motor control unit 90 presses the support portion 44 against the injection cylinder 22 and when the second motor control unit 92 pulls the support portion 44 in the rearward direction D2. However, the first rotational position P1 and the second rotational position P2 differ. One reason for this is that the mechanical part (second drive device 52) connecting the injection motor 62 and the support portion 44 includes backlash. More specifically, when controlled by the second motor control unit 92, the injection motor 62 can rotate in the second rotational direction within the range allowed by the backlash. As a result, the first rotational position P1 and the second rotational position P2 differ. Another reason for the difference between the first rotational position P1 and the second rotational position P2 is elastic deformation (distortion) that may occur in the injection device 16 due to the driving of the injection motor 62. For example, the shaft 62a is allowed to rotate in response to distortion of the second drive device 52, the support portion 44, the injection cylinder 22, etc. in the front-rear direction D. As a result, the first rotation position P1 and the second rotation position P2 may differ from each other.

[0068] The third motor control unit 94 executes third motor control, which will be described next, after the control by the second motor control unit 92. That is, after the control by the second motor control unit 92, the third motor control unit 94 controls the injection motor 62 to move the rotational position of the injection motor 62 to a third rotational position P3 and stop driving the injection motor 62. More specifically, the third motor control unit 94 stops the supply of power to the injection motor 62. The third rotational position P3 is a predetermined rotational position that falls within the range between the first rotational position P1 and the second rotational position P2 described above. This range includes the first rotational position P1 and the second rotational position P2. The third rotational position P3 is, for example, a rotational position (midpoint) exactly halfway between the first rotational position P1 and the second rotational position P2.

[0069] 5 is a number line illustrating the first rotational position P1, the second rotational position P2, and the third rotational position P3. The positive direction of this number line corresponds to the first rotational direction of the shaft 62a.

[0070] As described above, the first rotation position P1 is the rotation position of the injection motor 62 when the magnitude of the first torque is the limit torque while the support portion 44 is pressed against the injection cylinder 22. The second rotation position P2 is the rotation position of the injection motor 62 when the magnitude of the second torque is the limit torque while the second motor control is being performed. When the injection motor 62 is located at the first rotation position P1 during execution of the first motor control, a pressing force corresponding to the magnitude of the limit torque is applied to the support portion 44. When the injection motor 62 is located at the second rotation position P2 during execution of the second motor control, a pulling force corresponding to the magnitude of the limit torque is applied to the support portion 44. The pressing force and the pulling force are directed in opposite directions. The magnitudes of the pressing force and the pulling force are equal.

[0071] In this case, the force in the front-rear direction D applied to the support part 44 when the injection motor 62 is located at the third rotation position P3, which is the midpoint between the first rotation position P1 and the second rotation position P2, is zero. In other words, if the zero point of the pressure sensor 48 is appropriately set, the detection value (pressure value) based on the pressure sensor 48 when the injection motor 62 is located at the third rotation position P3 will be zero.

[0072] The zero point correction unit 96 can correct the zero point of the pressure sensor 48 based on the above. That is, the zero point correction unit 96 corrects the zero point of the pressure sensor 48 so that the detection value based on the pressure sensor 48 becomes zero when the third motor control unit 94 stops driving the injection motor 62. In this case, the zero point correction can be achieved, for example, by changing the correction amount used by the control device 12 to correct the pressure value obtained from the detection result of the pressure sensor 48. More specifically, for example, the zero point correction unit 96 adjusts the correction amount so that the result of correcting the pressure value based on the pressure sensor 48 based on the correction amount when the third motor control unit 94 stops driving the injection motor 62 indicates zero. In this way, the zero point correction unit 96 can correct the zero point.

[0073] FIG. 6 is a flowchart illustrating a method for controlling the injection device 16.

[0074] Based on the above-described program, the control device 12 can execute, for example, the control method shown in Fig. 6. This control method includes an electromagnet activation step S1, a first motor control step S2, a first rotational position acquisition step S3, and a second motor control step S4. This control method also includes a second rotational position acquisition step S5, a third rotational position acquisition step S6, a third motor control step S7, a zero-point correction step S8, and an electromagnet stop step S9.

[0075] In the electromagnet activation step (electromagnet control step) S1, the electromagnet control unit 88 starts supplying power to the electromagnet 98A, which generates an attractive force (magnetic force) between the injection cylinder 22 (rear end 22b) and the support portion 44.

[0076] In the first motor control step S2, the above-described first motor control is executed. That is, in the first motor control step S2, the first motor control unit 90 controls the injection motor 62 so that the injection member 24 and the support unit 44 move forward, thereby contacting and pressing the support unit 44 against the injection cylinder 22. In this case, the first motor control unit 90 limits the magnitude of the first torque, which is the torque of the injection motor 62 in the first rotational direction, to the magnitude of the limit torque based on the limit torque information 82. This allows the rotational position sensor 62b to detect the above-described first rotational position P1 in the first motor control step S2.

[0077] In the first rotational position acquisition step S3, the rotational position acquisition unit 86 acquires information indicating the first rotational position P1 detected by the rotational position sensor 62b.

[0078] If information indicating the first rotational position P1 is acquired, the process proceeds to a second motor control step S4, where the above-described second motor control is executed. That is, in the second motor control step S4, the second motor control unit 92 controls the injection motor 62 so that the injection member 24 and the support portion 44 move backward. In this case, the second motor control unit 92 limits the magnitude of the second torque, which is the torque of the injection motor 62 in the second rotational direction, to the magnitude of the limit torque based on the limit torque information 82. As a result, the support portion 44 is pulled in the rearward direction D2. By executing this second motor control, the rotational position sensor 62b can detect the above-described second rotational position P2 in the second motor control step S4.

[0079] In the second rotational position acquisition step S5, the rotational position acquisition unit 86 acquires information indicating the second rotational position P2 detected by the rotational position sensor 62b.

[0080] In the third rotational position acquisition step S6, information indicating the third rotational position P3 is acquired based on the information indicating the first rotational position P1 acquired in the first rotational position acquisition step S3 and the information indicating the second rotational position P2 acquired in the second rotational position acquisition step S5. For example, in the third rotational position acquisition step S6, the third motor control unit 94 calculates the third rotational position P3 based on the first rotational position P1 and the second rotational position P2. The third rotational position P3 is, for example, the midpoint between the first rotational position P1 and the second rotational position P2.

[0081] In third motor control step S7, the above-described third motor control is executed based on the information indicating the third rotational position P3 acquired in third rotational position acquisition step S6. That is, in third motor control step S7, the third motor control unit 94 controls the injection motor 62 to move the rotational position of the injection motor 62 to the third rotational position P3 and stop driving the injection motor 62.

[0082] In the zero point correction step S8, while the injection motor 62 is stopped, the zero point correction unit 96 corrects the zero point so that the detection value of the pressure sensor 48 becomes zero.

[0083] In electromagnet stop step S9, the electromagnet control unit 88 stops the power supply to the electromagnet 98A, thereby eliminating the attraction force between the injection cylinder 22 and the support portion 44. This allows the injection member 24 and the support portion 44 to be retracted.

[0084] This completes the control method shown in Fig. 6. Note that the electromagnet stopping step S9 may be executed before the zero point correction step S8.

[0085] The control device 12 can appropriately correct the zero point of the pressure sensor 48 .

[0086] Moreover, the number of times that the injection member 24 moves to correct the zero point of the pressure sensor 48 can be reduced to two: a forward movement that is performed to bring the injection cylinder 22 into contact with the support portion 44, and a backward movement that is performed after the electromagnet is stopped in step S9. In other words, the control device 12 can correct the zero point of the pressure sensor 48 while reducing the number of times that the injection member 24 moves.

[0087] 6 reduces the number of times that the injection member 24 moves, and therefore reduces the time required to execute the control method. In other words, because the number of times that the injection member 24 moves is reduced, the time required to correct the zero point of the pressure sensor 48 is also reduced.

[0088] Furthermore, by reducing the number of movements of the injection member 24, for example, the risk of air being drawn into the injection cylinder 22 from the injection port 34p due to multiple movements of the injection member 24 is reduced. By reducing the risk of air being drawn into the injection cylinder 22, the risk of the air drawn into the injection cylinder 22 causing molding material burns in the molding material in the injection cylinder 22 is also reduced.

[0089] Furthermore, according to this embodiment, the electromagnet control unit 88 controls the electromagnet 98A to switch between a state in which an attractive force is generated between the injection cylinder 22 and the support unit 44 and a state in which the attractive force is eliminated. As a result, for example, when the injection molding machine 10 is executing a molding cycle, the electromagnet control unit 88 can eliminate the attractive force. As a result, the attractive force is prevented from affecting the operation of the injection unit 16 during the execution of the molding cycle.

[0090] One embodiment may be modified as follows. In the following modifications, explanations that overlap with the embodiment will be omitted. In addition, in the drawings used in the following modifications, the same reference numerals are used for the same components as those described in the embodiment.

[0091] (Modification 1) The magnet used as the attraction member 98 is not limited to the electromagnet 98A, but may be a permanent magnet. In this case, for example, the entire support portion 44 may be formed of the attraction member (permanent magnet).

[0092] (Modification 2) FIG. 7 is a schematic diagram showing the configuration of an injection device 16 according to Modification 2. As shown in FIG.

[0093] The suction member 98 may be an adhesive sheet 98B provided on at least one of the injection cylinder 22 (rear end 22b) and the support portion 44. FIG. 7 shows an example in which the adhesive sheet 98B is provided on the front end portion 44a of the support portion 44. The adhesive sheet 98B can adhere the injection cylinder 22 and the support portion 44 to each other. That is, according to this modification, the adhesive sheet 98B can generate an adhesive force between the injection cylinder 22 and the support portion 44.

[0094] (Modification 3) The third rotational position P3 is not particularly limited as long as it is within the range between the first rotational position P1 and the second rotational position P2.

[0095] For example, after the second motor control (second motor control step S4) is executed, the third motor control unit 94 may stop the supply of power to the injection motor 62 without rotating the injection motor 62. In this case, the rotational position of the injection motor 62 naturally falls within the range between the first rotational position P1 and the second rotational position P2. In this case, there is no need to acquire the third rotational position P3, and therefore the third rotational position acquisition step S6 shown in FIG. 6 may be omitted. In this case, in the third motor control step S7, it is sufficient to simply stop the drive of the injection motor 62. This may shorten the time required to execute the control method compared to the first embodiment.

[0096] Furthermore, if it is not necessary to acquire the third rotational position P3, it is not necessary to acquire the first rotational position P1 and the second rotational position P2. Therefore, the first rotational position acquisition step S3 and the second rotational position acquisition step S5 shown in Fig. 6 may be omitted. If the first rotational position acquisition step S3, the second rotational position acquisition step S5, and the third rotational position acquisition step S6 are omitted, the rotational position acquisition unit 86 shown in Fig. 3 may be omitted.

[0097] (Combination of Multiple Modifications) The multiple modifications described above may be combined as appropriate within a range that does not cause contradictions.

[0098] According to the embodiment and the modification described above, the control device 12 and the control method can relatively quickly and accurately correct the zero point of the pressure sensor 48 .

[0099] The following additional notes are further disclosed regarding the above embodiment.

[0100] (Supplementary Note 1) A control device (12) of an injection device (16) according to the present disclosure is a control device for an injection device including an injection cylinder (22), an injection member (24) inserted into the injection cylinder and movable within the injection cylinder, a support part (44) connected to a rear end part (24c) of the injection member and supporting the injection member, an injection motor (62) that applies a driving force to the support part to move the injection member, and a pressure sensor (48) that detects a pressure applied to the support part, the control device including a first motor control part (90) that controls the injection motor so that the injection member and the support part move forward with a limited torque and presses the support part against the injection cylinder, a second motor control part (92) that controls the injection motor so that the injection member and the support part move backward with the limited torque after control by the first motor control part, and a pressure sensor (48) that controls the injection motor so that the injection member and the support part move forward with the limited torque after control by the second motor control part. a third motor control unit (94) that stops driving of the injection motor when the rotational position of the injection motor is within a range between a first rotational position (P1) of the injection motor when the support part is pressed against the injection cylinder under the control of the first motor control unit and a second rotational position (P2) of the injection motor when the control is performed by the second motor control unit; and a zero point correction unit (96) that corrects the zero point of the pressure sensor so that a detection value detected based on the pressure sensor becomes zero when the drive of the injection motor is stopped by the third motor control unit, wherein when the injection member and the support part move forward and the support part comes into contact with the injection cylinder, an adhesive force is generated between the support part and the injection cylinder, and a force of the support part moving due to the limit torque is smaller than the adhesive force.

[0101] (Supplementary Note 2) The control device for the injection device described in Supplementary Note 1 may be such that the first rotation position is the rotation position of the injection motor when the magnitude of the torque of the injection motor reaches the limit torque in a state where the support part is pressed against the injection cylinder, and the second rotation position is the rotation position of the injection motor when the magnitude of the torque of the injection motor reaches the limit torque in a state where control is being performed by the second motor control part.

[0102] (Supplementary Note 3) In the control device for the injection device according to Supplementary Note 1 or 2, the third motor control unit may be configured to stop the injection motor without rotating it after control by the second motor control unit.

[0103] (Supplementary Note 4) In the control device for the injection device described in Supplementary Note 1 or 2, the third motor control unit may be configured to, after control by the second motor control unit, control the injection motor to rotate the injection motor to a third rotation position (P3) located within a range from the first rotation position to the second rotation position, and then stop the injection motor.

[0104] (Supplementary Note 5) In the control device for the injection device according to Supplementary Note 4, the third rotation position may be a midpoint between the first rotation position and the second rotation position.

[0105] (Supplementary Note 6) In the control device of the injection device according to Supplementary Note 4 or 5, the third motor control unit may calculate the third rotational position based on the first rotational position and the second rotational position acquired from a rotational position sensor (62b) that detects the rotational position of the injection motor.

[0106] (Appendix 7) The control device for the injection device according to any one of Appendices 1 to 6 may be a control device for the injection device, wherein at least one of the support part and the injection cylinder is provided with a magnet that generates the adhesive force.

[0107] (Supplementary Note 8) The control device for the injection device according to Supplementary Note 7 may be configured such that the magnet includes an electromagnet (98A), and the control device for the injection device further includes an electromagnet control unit (88) that supplies power to the electromagnet to generate the adsorptive force.

[0108] (Appendix 9) The control device for the injection device described in any one of Appendices 1 to 6 may be a control device for the injection device, wherein at least one of the support part and the injection cylinder is provided with an adhesive sheet (98B) that generates the suction force.

[0109] (Supplementary Note 10) An injection molding system (SYS) according to the present disclosure is an injection molding system including the control device for the injection device according to any one of Supplementary Notes 1 to 9, and the injection device.

[0110] (Supplementary Note 11) A control method for an injection device (16) according to the present disclosure is a control method for an injection device including an injection cylinder (22), an injection member (24) inserted into the injection cylinder and movable within the injection cylinder, a support part (44) connected to a rear end part (24c) of the injection member and supporting the injection member, an injection motor (62) that applies a driving force to the support part to move the injection member, and a pressure sensor (48) that detects a pressure applied to the support part, the control method including a first motor control step (S2) of controlling the injection motor so that the injection member and the support part move forward with a limited torque to bring the support part into contact with and press against the injection cylinder, a second motor control step (S4) of controlling the injection motor after the first motor control step so that the injection member and the support part move backward with the limited torque, and a second motor control step (S5) of controlling the injection motor after the second motor control step to move the first motor. a third motor control step (S7) of stopping the drive of the injection motor in a state where the rotation position of the injection motor is within a range between a first rotation position (P1) of the injection motor in a state where the support part is pressed against the injection cylinder in the motor control step and a second rotation position (P2) of the injection motor in a state where the second motor control step is performed; and a zero point correction step (S8) of correcting a zero point of the pressure sensor so that a detection value detected based on the pressure sensor becomes zero in a state where the drive of the injection motor is stopped by the third motor control step, wherein when the injection member and the support part move forward and the support part comes into contact with the injection cylinder, an adhesive force is generated between the support part and the injection cylinder, and a force of the support part moving due to the limit torque is smaller than the adhesive force.

[0111] (Appendix 12) The control method for an injection device according to Appendix 11 may be such that the first rotation position is the rotation position of the injection motor when the magnitude of the torque of the injection motor reaches the limit torque in a state where the support part is pressed against the injection cylinder, and the second rotation position is the rotation position of the injection motor when the magnitude of the torque of the injection motor reaches the limit torque in a state where control is performed by the second motor control step.

[0112] (Supplementary Note 13) The control method of the injection device according to Supplementary Note 11 or 12 may be a control method of the injection device, wherein in the third motor control step, after the second motor control step, the injection motor is stopped without rotating.

[0113] (Supplementary Note 14) The control method of an injection device described in Supplementary Note 11 or 12 may be a control method of an injection device, wherein in the third motor control step, after the second motor control step, the injection motor is controlled to rotate the injection motor to a third rotation position (P3) located within a range from the first rotation position to the second rotation position, and then the injection motor is stopped.

[0114] (Supplementary Note 15) In the control method of the injection device according to Supplementary Note 14, the third rotational position may be a midpoint between the first rotational position and the second rotational position.

[0115] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments.

[0116] REFERENCE SIGNS LIST 12...Control device 16...Injection device 22...Injection cylinder 24...Injection member 24c...Rear end portion 44...Support portion 48...Pressure sensor 62...Injection motor 62b...Rotational position sensor 88...Electromagnet control portion 90...First motor control portion 92...Second motor control portion 94...Third motor control portion 96...Zero point correction portion 98A...Attraction member (electromagnet) 98B...Attraction member (adhesive sheet) P1...First rotation position P2...Second rotation position P3...Third rotation position SYS...Injection molding system

Claims

1. A control device for an injection device comprising an injection cylinder, an injection member inserted into the injection cylinder and movable within the injection cylinder, a support part connected to the rear end of the injection member and supporting the injection member, an injection motor that applies a driving force to the support part to move the injection member, and a pressure sensor that detects pressure applied to the support part, comprising: a first motor control part that controls the injection motor so that the injection member and the support part move forward with a limit torque, and presses the support part against the injection cylinder; a second motor control part that controls the injection motor so that the injection member and the support part move backward with the limit torque after control by the first motor control part; a third motor control unit that stops driving of the injection motor in a state where, after control by the second motor control unit, the rotational position of the injection motor is within a range between a first rotational position of the injection motor in a state where the support part is pressed against the injection cylinder by control of the first motor control unit and a second rotational position of the injection motor in a state where the control by the second motor control unit has been performed; and a zero point correction unit that corrects a zero point of the pressure sensor so that a detection value detected based on the pressure sensor becomes zero in a state where the drive of the injection motor is stopped by the third motor control unit, wherein when the injection member and the support part advance and the support part comes into contact with the injection cylinder, an adhesive force is generated between the support part and the injection cylinder, and a force of the support part moving due to the limit torque is smaller than the adhesive force.

2. A control device for an injection device as described in claim 1, wherein the first rotation position is the rotation position of the injection motor when the torque magnitude of the injection motor reaches the limit torque while the support part is pressed against the injection cylinder, and the second rotation position is the rotation position of the injection motor when the torque magnitude of the injection motor reaches the limit torque while control is being performed by the second motor control part.

3. A control device for an injection device according to claim 1 or 2, wherein the third motor control section stops the injection motor without rotating it after control by the second motor control section.

4. A control device for an injection device as described in claim 1 or 2, wherein the third motor control unit, after control by the second motor control unit, controls the injection motor to rotate the injection motor to a third rotation position located within a range from the first rotation position to the second rotation position, and then stops the injection motor.

5. A control device for an injection device according to claim 4, wherein the third rotational position is a midpoint between the first rotational position and the second rotational position.

6. A control device for an injection device according to claim 4 or 5, wherein the third motor control unit calculates the third rotational position based on the first rotational position and the second rotational position acquired from a rotational position sensor that detects the rotational position of the injection motor.

7. A control device for an injection device according to any one of claims 1 to 6, wherein at least one of the support section and the injection cylinder is provided with a magnet that generates the adhesive force.

8. A control device for an injection device according to claim 7, wherein the magnet includes an electromagnet, and the control device for an injection device further comprises an electromagnet control unit that supplies power to the electromagnet to generate the adsorptive force.

9. A control device for an injection device according to any one of claims 1 to 6, wherein at least one of the support section and the injection cylinder is provided with an adhesive sheet that generates the suction force.

10. An injection molding system comprising: a control device for an injection device according to any one of claims 1 to 9; and the injection device.

11. A control method for an injection device including an injection cylinder, an injection member inserted into the injection cylinder and movable within the injection cylinder, a support part connected to a rear end of the injection member and supporting the injection member, an injection motor that applies a driving force to the support part to move the injection member, and a pressure sensor that detects pressure applied to the support part, comprising: a first motor control step of controlling the injection motor so that the injection member and the support part move forward with a limit torque, thereby bringing the support part into contact with and pressing it against the injection cylinder; and a second motor control step of controlling the injection motor after the first motor control step so that the injection member and the support part move backward with the limit torque. a third motor control step of stopping driving of the injection motor in a state where, after the second motor control step, the rotational position of the injection motor is within a range between a first rotational position of the injection motor in a state where the support part is pressed against the injection cylinder in the first motor control step and a second rotational position of the injection motor in a state where the second motor control step is performed; and a zero point correction step of correcting a zero point of the pressure sensor so that a detection value detected based on the pressure sensor becomes zero in a state where the drive of the injection motor is stopped by the third motor control step, wherein when the injection member and the support part advance and the support part comes into contact with the injection cylinder, an adhesive force is generated between the support part and the injection cylinder, and a force of the support part moving due to the limit torque is smaller than the adhesive force.

12. A control method for an injection device as described in claim 11, wherein the first rotational position is the rotational position of the injection motor when the torque magnitude of the injection motor reaches the limit torque while the support part is pressed against the injection cylinder, and the second rotational position is the rotational position of the injection motor when the torque magnitude of the injection motor reaches the limit torque while control is being performed by the second motor control step.

13. A control method for an injection device according to claim 11 or 12, wherein in the third motor control step, after the second motor control step, the injection motor is stopped without rotating.

14. A control method for an injection device as claimed in claim 11 or 12, wherein in the third motor control step, after the second motor control step, the injection motor is controlled to rotate the injection motor to a third rotation position located within a range from the first rotation position to the second rotation position, and then the injection motor is stopped.

15. A method for controlling an injection device according to claim 14, wherein the third rotational position is a midpoint between the first rotational position and the second rotational position.

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