Control device for injection molding machine and injection molding machine

Abstract

The invention provides a control device of an injection molding machine and the injection molding machine, which can improve safety. A control device for an injection molding machine according to one embodiment includes: a digital circuit configured to detect a predetermined event when a signal indicating that the predetermined event has been detected is received from a detection unit provided in an injection molding machine including a motor configured to supply power for moving a movable portion and a brake of the motor; and a control unit that sequentially controls the output of a first signal for cutting off power for cutting off power supply to the motor and the output of a second signal for starting braking by the brake.

Description

[0001] This application claims priority based on Japanese Patent Application No. 2024-100441, filed on June 21, 2024. The entire contents of that Japanese application are incorporated herein by reference. Technical Field

[0002] This invention relates to a control device for an injection molding machine and an injection molding machine. Background Technology

[0003] In the past, various controls have been implemented to ensure safety when operating injection molding machines. For example, Patent Document 1 discloses an injection molding machine comprising: a safety door; a detection unit for detecting the opening and closing state of the safety door; and a control unit for stopping the drive unit based on the detection result of the detection unit. The control unit of this injection molding machine switches a switch as the safety door opens, thereby de-energizing the coil of the relay switch that operates the motor drive unit of the mold clamping mechanism to stop the motor drive unit.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2007-230113

[0005] In actual injection molding machines, when the movable part is stopped, the following processes tend to occur: power cut-off of the actuator that actuates the movable part; and braking control based on the brake used to stop the actuator. In actual injection molding machines, power cut-off and braking control are performed by different devices. Because they are performed by different devices, it is difficult to adjust the operation to be performed with high precision in the sequence of power cut-off and braking control when the movable part is stopped. Summary of the Invention

[0006] One aspect of the present invention provides a technique for improving the reliability of actions performed in sequence of power cut-off and braking control to enhance safety.

[0007] One aspect of the present invention relates to a control device for an injection molding machine, comprising: a digital circuit that, upon receiving a signal from a detection unit of an injection molding machine equipped with a motor for moving a movable part and a brake for the motor indicating that a predetermined event has been detected, sequentially controls the output of a first signal to cut off the power supply to the motor and the output of a second signal to start braking based on the brake.

[0008] Invention Effects

[0009] According to one aspect of the invention, the reliability of actions performed in sequence of power cut-off and braking control is improved to enhance safety. Attached Figure Description

[0010] Figure 1This is a diagram showing the state of an injection molding machine at the end of mold opening according to one embodiment.

[0011] Figure 2 This is a diagram showing the state of the injection molding machine during mold closing according to one embodiment.

[0012] Figure 3 This is a diagram illustrating an example of the electrical structure of the PLC according to the first embodiment.

[0013] Figure 4 This is a functional structure diagram showing the main structure of the control device and PLC involved in the first embodiment.

[0014] Figure 5 This is a timing diagram of power cut-off and brake control based on the brake when the safety door is opened in the injection molding machine according to the first embodiment.

[0015] Figure 6 This is a diagram illustrating an example of the electrical structure of the PLC according to the second embodiment.

[0016] In the diagram: 10-Injection molding machine, 160-Clamping motor, 162-Motor brake, 183-Mold thickness adjustment motor, 186-Motor brake, 221-Ejection motor, 221A-Motor driver, 222-Motor brake, 350-Injection motor, 352-Motor brake, 700-Control device, 701-CPU, 711-Input processing unit, 712-Speed ​​control unit, 710-PLC, 720-Arithmetic unit, 721-Input processing unit, 722-Measurement unit, 723-Driver control unit, 724-Brake control unit, 730-Memory, 731-Input unit, 732-Output unit, 751-Emergency stop button, 752-Other safety sensors, 940-Housing, 941-Safety door, 942-Opening / closing detector. Detailed Implementation

[0017] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, the embodiments described below are illustrative and not limiting of the invention; all features and combinations thereof described in the embodiments are not necessarily the essence of the invention. Additionally, in the accompanying drawings, the same or corresponding structures are sometimes labeled with the same or corresponding symbols, and descriptions are omitted.

[0018] Figure 1 This is a diagram showing the state of the injection molding machine according to the first embodiment at the end of mold opening. Figure 2This diagram illustrates the state of the injection molding machine according to the first embodiment during mold closing. In this specification, the X-axis, Y-axis, and Z-axis are mutually perpendicular directions. The X-axis and Y-axis represent horizontal directions, and the Z-axis represents vertical directions. When the mold closing device 100 is horizontal, the X-axis is the mold opening and closing direction, and the Y-axis is the width direction of the injection molding machine 10. The negative side of the Y-axis is referred to as the operating side, and the positive side of the Y-axis is referred to as the opposite side of the operating side.

[0019] like Figures 1-2 As shown, the injection molding machine 10 includes: a mold clamping device 100, a mold opening and closing device 800; an ejection device 200 for ejecting the molded article formed by the mold device 800; an injection device 300 for injecting molding material into the mold device 800; a moving device 400 for moving the injection device 300 forward and backward relative to the mold device 800; a control device 700 for controlling each component of the injection molding machine 10; and a frame 900 for supporting each component of the injection molding machine 10. The frame 900 includes a mold clamping device frame 910 supporting the mold clamping device 100 and an injection device frame 920 supporting the injection device 300. The mold clamping device frame 910 and the injection device frame 920 are respectively mounted on the floor 2 via horizontal adjusting casters 930. The control device 700 is arranged in the internal space of the injection device frame 920. The components of the injection molding machine 10 will be described below.

[0020] (Mold closing device)

[0021] In the description of the mold closing device 100, the moving direction of the movable pressure plate 120 when the mold is closed (e.g., the positive X-axis direction) is set to forward, and the moving direction of the movable pressure plate 120 when the mold is opened (e.g., the negative X-axis direction) is set to rearward.

[0022] The mold closing device 100 performs mold closing, pressurization, mold closing, demolding, and mold opening of the mold assembly 800. The mold assembly 800 includes a fixed mold 810 and a movable mold 820. The mold closing device 100 is, for example, horizontal, and the mold opening and closing direction is horizontal. The mold closing device 100 has a fixed pressure plate 110 for mounting the fixed mold 810, a movable pressure plate 120 for mounting the movable mold 820, and a moving mechanism 102 for moving the movable pressure plate 120 relative to the fixed pressure plate 110 in the mold opening and closing direction.

[0023] The fixed pressure plate 110 is fixed relative to the mold closing device frame 910. The fixed mold 810 is installed on the surface of the fixed pressure plate 110 opposite to the movable pressure plate 120.

[0024] The movable pressure plate 120 is configured to move freely relative to the mold clamping device frame 910 in the mold opening and closing direction. A guide member 101 for guiding the movable pressure plate 120 is laid on the mold clamping device frame 910. A movable mold 820 is mounted on the surface of the movable pressure plate 120 opposite to the fixed pressure plate 110.

[0025] The moving mechanism 102 performs mold closing, pressurization, mold clamping, demolding, and mold opening of the mold device 800 by moving the movable pressure plate 120 forward and backward relative to the fixed pressure plate 110. The moving mechanism 102 includes an toggle seat 130 spaced apart from the fixed pressure plate 110, a connecting rod 140 connecting the fixed pressure plate 110 and the toggle seat 130, an toggle mechanism 150 that moves the movable pressure plate 120 relative to the toggle seat 130 in the mold opening and closing direction, a mold clamping motor 160 that operates the toggle mechanism 150, a motion conversion mechanism 170 that converts the rotational motion of the mold clamping motor 160 into linear motion, and a mold thickness adjustment mechanism 180 that adjusts the distance between the fixed pressure plate 110 and the toggle seat 130.

[0026] The toggle seat 130 is spaced apart from the fixed pressure plate 110 and is mounted on the mold clamping device frame 910 so as to move freely in the mold opening and closing direction. Furthermore, the toggle seat 130 can be configured to move freely along a guide laid on the mold clamping device frame 910. The guide of the toggle seat 130 can be interchangeable with the guide 101 of the movable pressure plate 120.

[0027] In addition, in this embodiment, the fixed pressure plate 110 is fixed relative to the mold clamping device frame 910, and the toggle seat 130 is configured to move freely relative to the mold clamping device frame 910 in the mold opening and closing direction. However, it is also possible that the toggle seat 130 is fixed relative to the mold clamping device frame 910, and the fixed pressure plate 110 is configured to move freely relative to the mold clamping device frame 910 in the mold opening and closing direction.

[0028] Connecting rod 140 connects the fixed pressure plate 110 and the toggle seat 130 at a distance L in the mold opening and closing direction. Multiple connecting rods 140 can be used (e.g., four). The multiple connecting rods 140 are configured parallel to the mold opening and closing direction and extend according to the clamping force. A connecting rod strain detector 141 for detecting the strain of the connecting rod 140 can be provided on at least one connecting rod 140. The connecting rod strain detector 141 sends a signal indicating its detection result to the control device 700. The detection result of the connecting rod strain detector 141 is used for detecting the clamping force, etc.

[0029] In this embodiment, a connecting rod strain gauge 141 is used as the clamping force detector for detecting the clamping force, but the present invention is not limited to this. The clamping force detector is not limited to a strain gauge and may also be piezoelectric, capacitive, hydraulic, or electromagnetic, etc., and its installation position is not limited to the connecting rod 140.

[0030] A toggle mechanism 150 is positioned between a movable pressure plate 120 and a toggle seat 130, allowing the movable pressure plate 120 to move relative to the toggle seat 130 in the mold opening and closing direction. The toggle mechanism 150 has a crosshead 151 that moves in the mold opening and closing direction and a pair of linkages that extend and retract with the movement of the crosshead 151. Each linkage has a first linkage 152 and a second linkage 153 connected by pins or the like, allowing for free extension and retraction. The first linkage 152 is mounted by pins or the like to allow for free oscillation relative to the movable pressure plate 120. The second linkage 153 is mounted by pins or the like to allow for free oscillation relative to the toggle seat 130. The second linkage 153 is mounted to the crosshead 151 via a third linkage 154. When the crosshead 151 moves forward or backward relative to the toggle seat 130, the first linkage 152 and the second linkage 153 extend and retract, causing the movable pressure plate 120 to move forward or backward relative to the toggle seat 130.

[0031] Furthermore, the structure of the toggle mechanism 150 is not limited to Figure 1 and Figure 2 The structure shown. For example, in Figure 1 and Figure 2 In this configuration, each link group has 5 nodes, but it can be 4, or it can be the node where one end of the third link 154 is connected to the first link 152 and the second link 153.

[0032] The clamping motor 160 is mounted on the toggle seat 130 and operates the toggle mechanism 150. The clamping motor 160 moves the crosshead 151 forward and backward relative to the toggle seat 130, causing the first link 152 and the second link 153 to extend and retract, thereby moving the movable pressure plate 120 forward and backward relative to the toggle seat 130. The clamping motor 160 is directly connected to the motion conversion mechanism 170, but can also be connected to the motion conversion mechanism 170 via a belt and pulleys.

[0033] The mold clamping motor 160 includes a built-in motor brake 162, which operates to stop the rotation of the motor shaft of the mold clamping motor 160 itself. The motor brake 162 is, for example, a non-excitation brake, which operates when the power supply is stopped.

[0034] The motion conversion mechanism 170 converts the rotary motion of the mold clamping motor 160 into the linear motion of the crosshead 151. The motion conversion mechanism 170 includes a lead screw shaft and a lead screw nut screwed to the lead screw shaft. Balls or rollers may be located between the lead screw shaft and the lead screw nut.

[0035] Under the control of the control device 700, the mold closing device 100 performs the mold closing process, the pressure raising process, the mold closing process, the pressure release process, and the mold opening process.

[0036] In the mold closing process, the mold closing motor 160 is driven to advance the crosshead 151 to the mold closing end position at a set speed, causing the movable pressure plate 120 to advance so that the moving mold 820 contacts the fixed mold 810. For example, a mold closing motor encoder 161 is used to detect the position and speed of the crosshead 151. The mold closing motor encoder 161 detects the rotation of the mold closing motor 160 and sends a signal indicating its detection result to the control device 700.

[0037] Furthermore, the crosshead position detector for detecting the position of the crosshead 151 and the crosshead movement speed detector for detecting the movement speed of the crosshead 151 are not limited to the mold clamping motor encoder 161; conventional detectors can be used. Similarly, the movable platen position detector for detecting the position of the movable platen 120 and the movable platen movement speed detector for detecting the movement speed of the movable platen 120 are not limited to the mold clamping motor encoder 161; conventional detectors can be used.

[0038] In the pressurization process, the mold clamping motor 160 is further driven to advance the crosshead 151 from the mold closing end position to the mold closing position, thereby generating a mold clamping force.

[0039] During the mold closing process, the mold closing motor 160 is driven to maintain the position of the crosshead 151 in the mold closing position. During the mold closing process, the mold closing force generated during the pressurization process is maintained. During the mold closing process, a cavity space 801 (see reference) is formed between the moving mold 820 and the fixed mold 810. Figure 2 The injection unit 300 fills the cavity space 801 with liquid molding material. The filled molding material is then cured to obtain a molded product.

[0040] The number of cavity spaces 801 can be one or more. In the latter case, multiple molded articles can be obtained simultaneously. An insert can be configured in a part of the cavity space 801, and the other part of the cavity space 801 can be filled with molding material. A molded article in which the insert and the molding material are integrated can be obtained.

[0041] During the depressurization process, the crosshead 151 is retracted from the mold-closing position to the mold-opening start position by driving the mold-closing motor 160, thereby causing the movable pressure plate 120 to retract and reducing the mold-closing force. The mold-opening start position and the mold-closing end position can be the same position.

[0042] In the mold opening process, the crosshead 151 is retracted from the mold opening start position to the mold opening end position at a set moving speed by driving the mold closing motor 160, causing the movable pressure plate 120 to retract, so that the moving mold 820 separates from the fixed mold 810. Then, the ejector device 200 ejects the molded product from the moving mold 820.

[0043] The setting conditions in the mold closing process, the pressure raising process, and the mold closing process are set uniformly as a series of setting conditions. For example, the moving speed, position (including the mold closing start position, moving speed switching position, mold closing end position, and mold closing position) and mold closing force of the crosshead 151 in the mold closing process and the pressure raising process are set uniformly as a series of setting conditions. The mold closing start position, moving speed switching position, mold closing end position, and mold closing position are arranged sequentially from back to front, and represent the start and end points of the range for setting the moving speed. The moving speed is set for each range. There can be one or more moving speed switching positions. The moving speed switching position can be omitted. Only the mold closing position and the mold closing force can be set.

[0044] The settings for the depressurization and mold opening processes are also set in the same way. For example, the moving speed and position (mold opening start position, moving speed switching position, and mold opening end position) of the crosshead 151 in the depressurization and mold opening processes are set uniformly as a series of settings. The mold opening start position, moving speed switching position, and mold opening end position are arranged sequentially from front to back, and represent the start and end points of the range for setting the moving speed. The moving speed is set for each range. There can be one or more moving speed switching positions. A moving speed switching position may not be set. The mold opening start position and the mold closing end position can be the same position. Furthermore, the mold opening end position and the mold closing start position can be the same position.

[0045] Alternatively, it can replace the moving speed and position of the crosshead 151 to set the moving speed and position of the movable pressure plate 120. Furthermore, it can replace the position of the crosshead (e.g., the mold closing position) and the position of the movable pressure plate to set the mold closing force.

[0046] However, the toggle mechanism 150 amplifies the driving force of the clamping motor 160 and transmits it to the movable pressure plate 120. This amplification factor is also known as the toggle ratio. The toggle ratio varies depending on the angle θ (hereinafter also referred to as "link angle θ") formed by the first link 152 and the second link 153. The link angle θ is determined by the position of the crosshead 151. The toggle ratio reaches its maximum when the link angle θ is 180°.

[0047] When the thickness of the mold assembly 800 changes due to replacement of the mold assembly 800, temperature changes of the mold assembly 800, etc., mold thickness adjustment is performed to obtain the specified mold closing force during mold closing. In mold thickness adjustment, for example, the distance L between the fixed pressure plate 110 and the toggle seat 130 is adjusted so that at the moment of mold contact when the moving mold 820 contacts the fixed mold 810, the connecting rod angle θ of the toggle mechanism 150 becomes the specified angle.

[0048] The mold clamping device 100 includes a mold thickness adjustment mechanism 180. The mold thickness adjustment mechanism 180 adjusts the distance L between the fixed pressure plate 110 and the toggle seat 130, thereby adjusting the mold thickness. Furthermore, the timing of the mold thickness adjustment is, for example, during the period from the end of the molding cycle to the start of the next molding cycle. The mold thickness adjustment mechanism 180 includes, for example: a lead screw shaft 181 formed at the rear end of the connecting rod 140; a lead screw nut 182 held in the toggle seat 130 for free rotation and immobility; and a mold thickness adjustment motor 183 that rotates the lead screw nut 182 screwed to the lead screw shaft 181.

[0049] Each connecting rod 140 is provided with a lead screw shaft 181 and a lead screw nut 182. The rotational driving force of the die thickness adjustment motor 183 can be transmitted to multiple lead screw nuts 182 via the rotational driving force transmission unit 185. Multiple lead screw nuts 182 can be rotated synchronously. Alternatively, multiple lead screw nuts 182 can be rotated individually by changing the transmission path of the rotational driving force transmission unit 185.

[0050] The rotary drive force transmission unit 185 is, for example, composed of gears. In this case, driven gears are formed on the outer periphery of each lead screw nut 182, drive gears are mounted on the output shaft of the die thickness adjustment motor 183, and intermediate gears that mesh with multiple driven gears and drive gears are kept rotatably in the center of the toggle seat 130. Alternatively, the rotary drive force transmission unit 185 may be composed of belts and pulleys instead of gears.

[0051] The operation of the die thickness adjustment mechanism 180 is controlled by the control device 700. The control device 700 drives the die thickness adjustment motor 183 to rotate the lead screw nut 182. As a result, the position of the toggle seat 130 relative to the connecting rod 140 is adjusted, and the distance L between the fixed pressure plate 110 and the toggle seat 130 is adjusted. Alternatively, multiple die thickness adjustment mechanisms can be used in combination.

[0052] The die thickness adjustment motor encoder 184 is used to detect the interval L. The die thickness adjustment motor encoder 184 detects the rotation amount and direction of the die thickness adjustment motor 183 and sends a signal indicating the detection result to the control device 700. The detection result of the die thickness adjustment motor encoder 184 is used for monitoring and controlling the position and interval L of the toggle seat 130. However, the toggle seat position detector for detecting the position of the toggle seat 130 and the interval detector for detecting the interval L are not limited to the die thickness adjustment motor encoder 184; conventional detectors can be used.

[0053] The die thickness adjustment motor 183 includes a built-in motor brake 186, which operates to stop the rotation of the motor shaft itself. The motor brake 186 is, for example, a non-excitation brake, which operates when the power supply is stopped.

[0054] The mold clamping device 100 may have a mold temperature regulator for adjusting the temperature of the mold assembly 800. The mold assembly 800 has a flow path for a temperature regulating medium inside it. The mold temperature regulator adjusts the temperature of the temperature regulating medium supplied to the flow path of the mold assembly 800, thereby regulating the temperature of the mold assembly 800.

[0055] In addition, the mold closing device 100 in this embodiment is a horizontal type with the mold opening and closing direction in the horizontal direction, but it can also be a vertical type with the mold opening and closing direction in the vertical direction.

[0056] Furthermore, the mold clamping device 100 of this embodiment has a mold clamping motor 160 as a drive source, but a hydraulic cylinder may be used instead of the mold clamping motor 160. Also, the mold clamping device 100 may have a linear motor for mold opening and closing, or it may have an electromagnet for mold clamping.

[0057] (Ejection device)

[0058] In the description of the ejector device 200, similarly to the description of the mold closing device 100, the moving direction of the movable pressure plate 120 when the mold is closed (e.g., the positive X-axis direction) is set to forward, and the moving direction of the movable pressure plate 120 when the mold is opened (e.g., the negative X-axis direction) is set to rearward.

[0059] Ejection device 200 is mounted on movable pressure plate 120 and moves forward and backward together with movable pressure plate 120. Ejection device 200 has ejection rod 210 for ejecting molded article from mold device 800 and drive mechanism 220 for moving ejection rod 210 along the moving direction (X-axis direction) of movable pressure plate 120.

[0060] Ejector rod 210 is configured to move freely in and out of the through hole in movable pressure plate 120. The front end of ejector rod 210 contacts ejector plate 826 of moving mold 820. The front end of ejector rod 210 may or may not be connected to ejector plate 826.

[0061] The drive mechanism 220 includes, for example, an ejector motor 221 and a motion conversion mechanism that converts the rotational motion of the ejector motor 221 into the linear motion of the ejector rod 210. The motion conversion mechanism includes a lead screw and a lead screw nut screwed to the lead screw. Balls or rollers may be located between the lead screw and the lead screw nut.

[0062] The ejector device 200 performs the ejection process under the control of the control device 700. In the ejection process, the ejector rod 210 is moved forward from the standby position to the ejection position at a set speed, causing the ejector plate 826 to move forward and eject the molded product. Then, the ejector motor 221 is driven to move the ejector rod 210 backward at a set speed, causing the ejector plate 826 to return to the original standby position.

[0063] For example, an ejector motor encoder is used to detect the position and movement speed of the ejector rod 210. The ejector motor encoder detects the rotation of the ejector motor 221 and sends a signal indicating its detection result to the control device 700. In addition, the ejector rod position detector for detecting the position of the ejector rod 210 and the ejector rod movement speed detector for detecting the movement speed of the ejector rod 210 are not limited to the ejector motor encoder, and conventional detectors can be used.

[0064] The ejector motor 221 includes a built-in motor brake 222, which operates to stop the rotation of the motor shaft of the ejector motor 221. The motor brake 222 is, for example, a de-energized brake, which operates when the power supply is stopped.

[0065] (Injection device)

[0066] In the description of the injection device 300, unlike the description of the mold clamping device 100 and the description of the ejection device 200, the direction of movement of the screw 330 during filling (e.g., the negative X-axis direction) is set to forward, and the direction of movement of the screw 330 during metering (e.g., the positive X-axis direction) is set to rearward.

[0067] An injection unit 300 is mounted on a sliding base 301, which is configured to move freely forward and backward relative to the injection unit frame 920. The injection unit 300 is also configured to move freely forward and backward relative to the mold assembly 800. The injection unit 300 contacts the mold assembly 800 and fills the cavity space 801 within the mold assembly 800 with molding material metered in the cylinder 310. The injection unit 300 includes, for example, a cylinder 310 for heating the molding material, a nozzle 320 located at the front end of the cylinder 310, a screw 330 configured to move freely forward and backward and rotate freely within the cylinder 310, a metering motor 340 for rotating the screw 330, an injection motor 350 for moving the screw 330 forward and backward, and a load detector 360 for detecting the load transmitted between the injection motor 350 and the screw 330.

[0068] The cylinder body 310 heats the molding material supplied to it from the supply port 311. The molding material includes, for example, resin. The molding material is formed in granular form and supplied to the supply port 311 in a solid state. The supply port 311 is formed at the rear of the cylinder body 310. A cooler 312, such as a water-cooled cylinder, is provided on the outer periphery of the rear of the cylinder body 310. A heater 313, such as a belt heater, and a temperature detector 314 are provided on the outer periphery of the cylinder body 310, further forward than the cooler 312.

[0069] The cylinder block 310 is divided into multiple regions along its axial direction (e.g., the X-axis direction). A heater 313 and a temperature detector 314 are respectively installed in each of the multiple regions. A set temperature is set for each of the multiple regions, and the control device 700 controls the heater 313 so that the temperature detected by the temperature detector 314 becomes the set temperature.

[0070] The nozzle 320 is located at the front end of the cylinder 310 and presses against the mold assembly 800. A heater 313 and a temperature detector 314 are provided on the outer periphery of the nozzle 320. The control device 700 controls the heater 313 so that the detected temperature of the nozzle 320 becomes the set temperature.

[0071] The screw 330 is configured to rotate freely and move forward and backward within the cylinder 310. When the screw 330 is rotated, molding material is conveyed forward along the spiral grooves of the screw 330. As the molding material is conveyed forward, it is gradually melted by heat from the cylinder 310. As the liquid molding material is conveyed forward and accumulates at the front of the cylinder 310, the screw 330 retracts. Then, when the screw 330 is moved forward, the liquid molding material accumulated at the front of the screw 330 is injected from the nozzle 320 and fills the mold assembly 800.

[0072] The check ring 331 is installed at the front of the screw 330 so that it can move freely forward and backward. The check ring 331 acts as a check valve to prevent the molding material from flowing backward from the front of the screw 330 when the screw 330 is pushed forward.

[0073] When the screw 330 is advanced, the check ring 331 is pushed backward by the pressure of the molding material in front of the screw 330, and retracts relative to the screw 330 to a closed position that blocks the flow path of the molding material (see reference). Figure 2 This prevents the molding material accumulated in front of the screw 330 from flowing backward.

[0074] On the other hand, when the screw 330 is rotated, the check ring 331 is pushed forward by the pressure of the molding material being conveyed forward along the spiral groove of the screw 330, and advances relative to the screw 330 to the open position where the flow path of the molding material is opened (see reference). Figure 1 Thus, the molding material is conveyed to the front of the screw 330.

[0075] The check ring 331 can be either a cotransformer that rotates with the screw 330 or a non-cotransformer that does not rotate with the screw 330.

[0076] Additionally, the injection device 300 may have a drive source that moves the check ring 331 back and forth relative to the screw 330 between an open position and a closed position.

[0077] The metering motor 340 rotates the screw 330. The drive source for rotating the screw 330 is not limited to the metering motor 340; for example, it could be a hydraulic pump.

[0078] The injection motor 350 moves the screw 330 forward and backward. A motion conversion mechanism is provided between the injection motor 350 and the screw 330 to convert the rotational motion of the injection motor 350 into the linear motion of the screw 330. This motion conversion mechanism may include, for example, a lead screw shaft and a lead screw nut screwed to the lead screw shaft. Ball bearings, rollers, etc., may be provided between the lead screw shaft and the lead screw nut. The drive source for moving the screw 330 forward and backward is not limited to the injection motor 350; for example, it may be a hydraulic cylinder.

[0079] The injection motor 350 includes a built-in motor brake 352, which operates to stop the rotation of the motor shaft itself. The motor brake 352 is, for example, a de-energized brake, which operates when the power (signal) supply stops.

[0080] Load detector 360 detects the load transmitted between injection motor 350 and screw 330. The detected load is converted into pressure by control device 700. Load detector 360 is positioned along the load transmission path between injection motor 350 and screw 330, and detects the load acting on load detector 360.

[0081] The load detector 360 sends the detected load signal to the control device 700. The load detected by the load detector 360 is converted into the pressure acting between the screw 330 and the molding material, and is used for the control and monitoring of the back pressure of the screw 330 and the pressure acting from the screw 330 on the molding material.

[0082] Furthermore, the pressure detector for detecting the pressure of the molding material is not limited to the load detector 360; conventional detectors can be used. For example, a nozzle pressure sensor or a mold pressure sensor can be used. The nozzle pressure sensor is located at the nozzle 320.

[0083] The injection unit 300 performs metering, filling, and pressure holding processes under the control of the control unit 700. The filling and pressure holding processes can be collectively referred to as the injection process.

[0084] In the metering process, the metering motor 340 drives the screw 330 to rotate at a set speed, conveying the molding material forward along the spiral grooves of the screw 330. As a result, the molding material is gradually melted. As the molten molding material is conveyed forward of the screw 330 and accumulates at the front of the cylinder 310, the screw 330 retracts. For example, a metering motor encoder 341 is used to detect the rotational speed of the screw 330. The metering motor encoder 341 detects the rotation of the metering motor 340 and sends a signal indicating its detection result to the control device 700. However, the screw speed detector for detecting the rotational speed of the screw 330 is not limited to the metering motor encoder 341; conventional detectors can be used.

[0085] In the metering process, to limit the rapid retraction of the screw 330, the injection motor 350 can be driven to apply a set back pressure to the screw 330. For example, a load detector 360 can be used to detect the back pressure on the screw 330. If the screw 330 retracts to the metering end position and a specified amount of molding material accumulates in front of the screw 330, the metering process ends.

[0086] The position and speed of the screw 330 in the metering process are uniformly set as a series of preset conditions. For example, the metering start position, speed switching position, and metering end position are set. These positions are arranged sequentially from front to back and represent the start and end points of the set speed interval. The speed is set for each interval. There can be one or more speed switching positions. Alternatively, no speed switching position can be set. Furthermore, the back pressure is set for each interval.

[0087] In the filling process, the injection motor 350 is driven to advance the screw 330 at a set speed, filling the cavity space 801 within the mold assembly 800 with the liquid molding material accumulated in front of the screw 330. For example, an injection motor encoder 351 is used to detect the position and speed of the screw 330. The injection motor encoder 351 detects the rotation of the injection motor 350 and sends a signal indicating its detection result to the control device 700. If the screw 330 reaches the set position, a switch is made from the filling process to the holding pressure process (so-called V / P switching). The position where the V / P switching occurs is also called the V / P switching position. The set speed of the screw 330 can be changed according to the position of the screw 330, time, etc.

[0088] The position and moving speed of the screw 330 in the filling process are uniformly set as a series of preset conditions. For example, the filling start position (also called the "injection start position"), the moving speed switching position, and the V / P switching position are set. These positions are arranged sequentially from back to front and represent the start and end points of the set moving speed interval. The moving speed is set for each interval. There can be one or more moving speed switching positions. It is also possible not to set any moving speed switching positions.

[0089] The upper limit of the pressure of the screw 330 is set for each range of the screw 330's moving speed. The pressure of the screw 330 is detected by the load detector 360. When the pressure of the screw 330 is below the set pressure, the screw 330 moves forward at the set moving speed. On the other hand, when the pressure of the screw 330 exceeds the set pressure, in order to protect the mold, the screw 330 moves forward at a slower moving speed than the set moving speed, so that the pressure of the screw 330 falls below the set pressure.

[0090] Furthermore, during the filling process, after the screw 330 reaches the V / P switching position, it can be paused at the V / P switching position before the V / P switch is performed. Alternatively, instead of stopping the screw 330, it can be moved forward or backward at a slight speed before the V / P switch is about to occur. Moreover, the screw position detector for detecting the position of the screw 330 and the screw speed detector for detecting the movement speed of the screw 330 are not limited to the injection motor encoder 351; conventional detectors can be used.

[0091] During the holding pressure process, the injection motor 350 pushes the screw 330 forward, maintaining the pressure of the molding material at the front end of the screw 330 (hereinafter also referred to as "holding pressure") at a set pressure, and pushing the remaining molding material in the cylinder 310 towards the mold assembly 800. This replenishes the amount of molding material in the mold assembly 800 that is insufficient due to cooling shrinkage. For example, a load detector 360 is used to detect the holding pressure. The set value of the holding pressure can be changed according to the elapsed time since the start of the holding pressure process. The holding pressure and the holding time of the holding pressure can be set separately for multiple holding pressure processes, or they can be set uniformly as a series of setting conditions.

[0092] During the holding pressure process, the molding material in the cavity space 801 within the mold assembly 800 is gradually cooled. At the end of the holding pressure process, the inlet of the cavity space 801 is blocked by the solidified molding material. This state is called gate sealing, which prevents the backflow of molding material from the cavity space 801. After the holding pressure process, the cooling process begins. During the cooling process, the molding material within the cavity space 801 solidifies. To shorten the molding cycle time, a metering process can be performed during the cooling process.

[0093] Furthermore, the injection device 300 in this embodiment is a coaxial screw type, but it can also be a pre-plasticizing type, etc. In a pre-plasticizing type injection device, molten molding material in a plasticizing cylinder is supplied to the injection cylinder, and the molding material is injected from the injection cylinder into the mold device. In the plasticizing cylinder, the screw is configured to rotate freely but not retract, or the screw is configured to rotate freely and retract freely. On the other hand, in the injection cylinder, the plunger is configured to retract freely.

[0094] Furthermore, the injection device 300 in this embodiment is horizontal with the cylinder 310's axis in the horizontal direction, but it can also be vertical with the cylinder 310's axis in the vertical direction. The mold clamping device combined with the vertical injection device 300 can be either vertical or horizontal. Similarly, the mold clamping device combined with the horizontal injection device 300 can be either horizontal or vertical.

[0095] (Mobile device)

[0096] In the description of the moving device 400, similarly to the description of the injection device 300, the direction of movement of the screw 330 during filling (e.g., the negative X-axis direction) is set to forward, and the direction of movement of the screw 330 during metering (e.g., the positive X-axis direction) is set to rearward.

[0097] The moving device 400 causes the injection device 300 to move forward and backward relative to the mold device 800. Furthermore, the moving device 400 presses the nozzle 320 relative to the mold device 800 to generate nozzle contact pressure. The moving device 400 includes a hydraulic pump 410, a motor 420 as a drive source, and a hydraulic cylinder 430 as a hydraulic actuator.

[0098] The hydraulic pump 410 has a first port 411 and a second port 412. The hydraulic pump 410 is a bidirectional rotating pump, generating hydraulic pressure by switching the rotation direction of the motor 420, drawing in working fluid (e.g., oil) from either the first port 411 or the second port 412 and discharging it from the other port. Alternatively, the hydraulic pump 410 can also draw working fluid from a tank and discharge working fluid from either the first port 411 or the second port 412.

[0099] Motor 420 operates hydraulic pump 410. Motor 420 drives hydraulic pump 410 by means of rotational direction and torque corresponding to control signals from control device 700. Motor 420 can be an electric motor or an electric servo motor.

[0100] The hydraulic cylinder 430 has a cylinder body 431, a piston 432, and a piston rod 433. The cylinder body 431 is fixed relative to the injection device 300. The piston 432 divides the interior of the cylinder body 431 into a front chamber 435, which is a first chamber, and a rear chamber 436, which is a second chamber. The piston rod 433 is fixed relative to the fixed pressure plate 110.

[0101] The front chamber 435 of the hydraulic cylinder 430 is connected to the first port 411 of the hydraulic pump 410 via a first flow path 401. Working fluid ejected from the first port 411 is supplied to the front chamber 435 via the first flow path 401, thereby propelling the injection device 300 forward. As the injection device 300 advances, the nozzle 320 is pressed against the fixed mold 810. The front chamber 435 functions as a pressure chamber, generating the nozzle contact pressure of the nozzle 320 through the pressure of the working fluid supplied from the hydraulic pump 410.

[0102] On the other hand, the rear chamber 436 of the hydraulic cylinder 430 is connected to the second port 412 of the hydraulic pump 410 via the second flow path 402. The working fluid ejected from the second port 412 is supplied to the rear chamber 436 of the hydraulic cylinder 430 via the second flow path 402, thereby pushing the injection device 300 backward. The injection device 300 retracts and the nozzle 320 separates from the fixed mold 810.

[0103] In addition, in this embodiment, the moving device 400 includes a hydraulic cylinder 430, but the present invention is not limited thereto. For example, instead of the hydraulic cylinder 430, an electric motor and a motion conversion mechanism that converts the rotational motion of the electric motor into the linear motion of the injection device 300 may also be used.

[0104] (Control device)

[0105] The control device 700 is, for example, composed of a computer, such as Figures 1-2 As shown, the device includes a CPU (Central Processing Unit) 701, a storage medium 702 such as memory, an input interface 703, an output interface 704, and a communication interface 705. The control device 700 performs various controls by causing the CPU 701 to execute programs stored in the storage medium 702. Furthermore, the control device 700 receives signals from external sources through the input interface 703 and sends signals to external sources through the output interface 704.

[0106] The control device 700 repeatedly produces molded products by performing metering, mold closing, pressurizing, mold closing, filling, pressure holding, cooling, depressurizing, mold opening, and ejection processes. The series of actions used to obtain the molded product, such as the actions from the start of the metering process to the start of the next metering process, is also called "material injection" or "molding cycle." Furthermore, the time required for one material injection is also called "molding cycle time" or "cycle time."

[0107] A typical molding cycle may include, for example, the following steps in sequence: metering, mold closing, pressure increase, mold closing, filling, pressure holding, cooling, pressure release, mold opening, and ejection. This sequence refers to the order in which each step begins. The filling, pressure holding, and cooling steps occur during the mold closing step. Alternatively, the start of the mold closing step can coincide with the start of the filling step. The end of the pressure release step can coincide with the start of the mold opening step.

[0108] Furthermore, to shorten the molding cycle time, multiple processes can be performed simultaneously. For example, the metering process can be performed during the cooling process of the previous molding cycle or during the mold closing process. In this case, the mold closing process can be set to be performed at the beginning of the molding cycle. The filling process can also begin during the mold closing process. Furthermore, the ejection process can begin during the mold opening process. When an on / off valve is provided for the flow path of the nozzle 320, the mold opening process can begin during the metering process. This is because even if the mold opening process begins during the metering process, as long as the on / off valve closes the flow path of the nozzle 320, the molding material will not leak from the nozzle 320.

[0109] In addition, a single molding cycle can include processes other than metering, mold closing, pressurization, mold closing, filling, pressure holding, cooling, depressurization, mold opening, and ejection.

[0110] For example, a pre-metering back suction process can be performed after the pressure holding process ends and before the metering process begins, to retract the screw 330 to a pre-set metering start position. This reduces the pressure of the molding material accumulated in front of the screw 330 before the metering process begins, and prevents the screw 330 from retracting abruptly when the metering process begins.

[0111] Furthermore, a post-metering back suction process can be performed after the metering process is completed and before the filling process begins, retracting the screw 330 to a pre-set filling start position (also known as the "injection start position"). This reduces the pressure of the molding material accumulated in front of the screw 330 before the filling process begins, thus preventing leakage of the molding material from the nozzle 320 before the filling process begins.

[0112] The control device 700 is connected to the operation device 750, which accepts user input, and the display device 760, which displays a screen. The operation device 750 and the display device 760 are, for example, composed of a touch panel 770, and can be integrated. The touch panel 770, as the display device 760, displays a screen under the control of the control device 700. Information such as the settings of the injection molding machine 10 and the current status of the injection molding machine 10 can be displayed on the screen of the touch panel 770. The touch panel 770 can accept operations on the displayed screen area. Furthermore, operation sections such as buttons and input fields for accepting user input can be displayed on the screen area of ​​the touch panel 770. The touch panel 770, as the operation device 750, detects user input on the screen and outputs a signal corresponding to the input operation to the control device 700. Thus, for example, the user can confirm the information displayed on the screen while simultaneously operating the operation sections set on the screen to set the injection molding machine 10 (including inputting setting values). Furthermore, by operating the operation sections set on the screen, the user can cause the injection molding machine 10 corresponding to the operation sections to operate. Furthermore, the operation of the injection molding machine 10 can include, for example, the operation (including stopping) of the mold clamping device 100, the ejection device 200, the injection device 300, the moving device 400, etc. Also, the operation of the injection molding machine 10 can include switching the screen displayed on the touch panel 770, which is a display device 760.

[0113] Furthermore, while the operation device 750 and display device 760 of this embodiment are integrated into a touch panel 770, they can also be provided independently. Additionally, multiple operation devices 750 can be provided. The operation device 750 and display device 760 are disposed on the operation side (negative Y-axis direction) of the mold clamping device 100 (more specifically, the fixed pressure plate 110).

[0114] (Safety Features)

[0115] And, as Figure 1 and Figure 2 As shown by the double-dotted line, the injection molding machine 10 has a housing 940 that covers the clamping device 100, the ejection device 200, and the mold assembly 800. During injection molding, the housing 940 serves to protect the user of the injection molding machine 10 from contact with the mold assembly 800, etc. Furthermore, the housing 940 may have a structure that covers up to the injection assembly 300 or a structure that covers the entire injection molding machine 10.

[0116] For example, the outer casing 940 is formed in a rectangular shape (box-shaped) and is fixed to the upper surface of the frame 900 (mold clamping device frame 910). An opening (not shown) is provided on the positive X-axis side of the outer casing 940, which allows the cylinder 310 and nozzle 320 of the injection device 300 to move forward and backward.

[0117] Furthermore, the outer casing 940 has one or more security doors 941 that can be opened and closed by the user. Figure 1 and Figure 2 The illustration shows an example of a housing 940 with the safety door 941 positioned on the side of the housing 940 in the positive Y-axis direction (in the paper). However, the position of the safety door 941 is not particularly limited; it can be on the side in the negative Y-axis direction, the side in the negative X-axis direction, or the upper surface in the positive Z-axis direction. The safety door 941 can be any of the single-opening, sliding, or double-opening types.

[0118] Furthermore, the injection molding machine 10 has an opening / closing detector 942 that detects the opening / closing state of the safety door 941. Regarding the type of opening / closing detector 942 involved in this embodiment, for example, a mechanical switch is used, which switches the output current on and off according to the opening / closing state of the safety door 941. Moreover, this embodiment does not limit the type of opening / closing detector 942; for example, an optical sensor may also be used.

[0119] The opening / closing detector 942 is communicatively connected to the PLC (Programmable Logic Controller) 710 and the control device 700 located in the internal space 922 on the lower vertical side of the injection device frame 920, and sends a signal indicating the opening / closing status of the safety door 941.

[0120] PLC710 is a computer that processes data according to the sequence specified in a pre-stored program, representing an example of digital circuitry used to ensure the safety of injection molding machine 10.

[0121] In this embodiment, a safety PLC (used to build a safety control system compliant with international safety standards (ISO 13849 or IEC 61508)) is used as an example of PLC 710. For example, an IC chip certified by the safety standard can be used as the arithmetic unit 720 of PLC 710. In the PLC 710 involved in this embodiment, there are storage areas for processing safety information and storage areas for processing non-safety information. Therefore, even if a malfunction occurs in the storage area for processing non-safety information, it is possible to suppress the impact on safety information. In addition, this embodiment describes the use of a safety PLC as an example of PLC 710, but it is not limited to using a safety PLC. A general-purpose PLC or a control device using other processors (CPU, GPU, ASIC, FPGA, etc.) can be used.

[0122] Furthermore, in the PLC710 (described later), the input section 731 and the output section 732, etc., are multiplexed / redundant. In addition, the PLC710 uses a self-test function to perform self-diagnosis of the structures included in the PLC710, thereby preventing the continuation of processing based on the injection molding machine 10 when an abnormality occurs in the PLC710.

[0123] Figure 3 This diagram illustrates an example of the electrical structure of the PLC710 according to this embodiment. (As shown...) Figure 3 As shown, the PLC710 includes an input unit 731, an output unit 732, an arithmetic unit 720, and a memory 730.

[0124] The arithmetic unit 720 is provided to control the operation of the PLC 710 and performs safety-related controls of the injection molding machine 10 according to a pre-made program. For example, in the event of a specified event, the arithmetic unit 720 performs control to stop the movable part.

[0125] The memory 730 is a storage area used to store the data (data signals) used by the arithmetic unit 720.

[0126] The input unit 731 is connected to at least one of the various sensors, switches and buttons provided in the injection molding machine 10, and receives signals output from the input devices.

[0127] For example, a signal indicating the detection result from the opening / closing detector 942 that detects the opening / closing state of the safety door 941 is input to the input unit 731. Furthermore, a signal indicating whether the emergency stop button 751 has been pressed is input to the input unit 731. Additionally, signals indicating the detection results from other safety sensors 752 installed in the injection molding machine 10 are input to the input unit 731.

[0128] The output unit 732 is connected to a mechanism for controlling a movable part provided in the injection molding machine 10, and outputs a signal to that mechanism. The signal output from the output unit 732 is, for example, a 24V voltage signal.

[0129] For example, the output unit 732 can output a 24V voltage signal to the motor driver 221A used to drive the ejector motor 221. The output unit 732 according to this embodiment switches whether to output a 24V voltage signal according to the program being executed in the arithmetic unit 720.

[0130] Furthermore, the output unit 732 is capable of outputting a 24V voltage signal to the motor brake 222 used to stop the ejector motor 221. In this embodiment, the output unit 732 switches between outputting a 24V voltage signal and not outputting it based on the program being executed in the arithmetic unit 720.

[0131] Figure 3 The PLC 710 shown represents a mechanism for controlling the ejector motor 221, but the controlled object of the PLC 710 is not limited to the ejector motor 221. Any mechanism used to drive the movable part provided on the injection molding machine 10 can be used; for example, the PLC 710 can control the injection motor 350, the mold thickness adjustment motor 183, and the mold clamping motor 160. Furthermore, the PLC 710 can control the injection molding machine movement motor that moves the injection molding machine 10 from the frame (not shown).

[0132] For example, the output unit 732 can output a 24V voltage signal to the motor driver for driving the injection motor 350 and the motor brake 352 for stopping the injection motor 350.

[0133] In addition, the output unit 732 can output a 24V voltage signal to the motor driver for driving the die thickness adjustment motor 183 and the motor brake 186 for stopping the die thickness adjustment motor 183.

[0134] In addition, the output unit 732 is capable of outputting a 24V voltage signal to the motor driver for driving the mold clamping motor 160 and the motor brake 162 for stopping the mold clamping motor 160.

[0135] The following describes the sequence in which the output unit 732 controls the ejector motor 221. However, since the other injection motors 350, mold thickness adjustment motor 183, mold clamping motor 160, and (not shown) injection molding machine movement motor are also controlled in the same way, the description is omitted.

[0136] For example, during the operation of the injection molding machine 10, if the input unit 731 receives a signal indicating that the safety door 941 has been opened (an example of a predetermined event) detected by the opening / closing detector 942 (an example of a detection unit), the arithmetic unit 720 controls the output of a (24V voltage) signal (an example of a first signal) to the motor driver 221A to cut off the power supply to the ejector motor 221, and controls the output of a (24V voltage) signal (an example of a second signal) to the motor brake 222 to begin braking the ejector motor 221. The arithmetic unit 720 in this embodiment controls the output of the power cut-off signal (an example of a first signal) and the output of the braking signal to begin braking the ejector motor 221 (an example of a second signal) in that order. For example, the control of the power cut-off signal output is set to stop the 24V voltage signal, and the control of the braking signal output is set to stop the 24V voltage signal. Furthermore, this embodiment shows an example of control with a stop voltage signal as the output signal, but it can be specified according to the embodiment. For example, it can also be the output of a stop signal for cutting off power or the output of a control signal for driving the motor brake.

[0137] Conventionally, stopping a movable part (e.g., ejector rod or moving mold) installed in an injection molding machine tends to be done by separate control devices: power cut-off for the actuator that moves the movable part; and braking control based on a brake used to stop the actuator. While timing can be roughly followed by assembling a delay circuit simulated by a relay board, the delay time can become excessively long because it varies depending on the components.

[0138] Thus, when the movable part is stopped by executing the safety function, the timing of the braking control after the power is cut off tends to deviate. If the time from the power cut-off to the start of braking by the brake is set too long, the stopping of the movable part will be delayed, which may sometimes put a load on the components of the injection molding machine, especially the components of the mold assembly or the molded product.

[0139] Furthermore, if the time from the start of power cut-off to the start of braking by the brake is set too short, the power cut-off for the actuator that moves the movable part and the start of braking based on the brake that stops the actuator may sometimes be reversed due to the timing discrepancy. In this case, as a result of power cut-off after braking control, braking control based on the brake is performed during the actuator's operation, thus causing wear caused by brake drag.

[0140] Therefore, in this embodiment, power cut-off and braking control are performed by a PLC 710. That is, by using a single PLC 710, control can be performed in a manner that follows the sequence of power cut-off and braking control when an event occurs that should stop the movable part (an example of a predetermined event). The PLC 710 controls the signals in a manner that follows the sequence of power cut-off and braking, thereby improving safety.

[0141] Figure 4 This is a functional structure diagram showing the main structures of the control device 700 and PLC 710 involved in this embodiment. Figure 4 The control device 700 and PLC 710 of the injection molding machine 10 are shown in the function block diagram. Figure 3 The functional blocks shown are conceptual and do not necessarily need to be physically configured as illustrated. All or part of each functional block can be functionally or physically distributed / integrated in any unit. In the control device 700, all or any part of the processing functions performed in each functional block are implemented by a program executed by the CPU 701. Alternatively, each functional block can be implemented as hardware based on wiring logic.

[0142] like Figure 4 As shown, the CPU 701 of the control device 700 includes, for example, an input processing unit 711 and a speed control unit 712.

[0143] The input processing unit 711 performs input processing on signals from sensors installed in the injection molding machine 10 that indicate the detection results of those sensors. For example, the input processing unit 711 performs input processing on signals from the opening / closing detector 942 that indicate the opening / closing state of the safety door 941.

[0144] The speed control unit 712 controls the speed of the actuator via the motor driver based on the signal processed by the input processing unit 711. For example, if the speed control unit 712 recognizes that the safety door 941 is open based on the signal processed by the input processing unit 711, it outputs a command to the motor driver 221A to reduce the speed of the ejector motor 221.

[0145] In the PLC710, all or any part of the processing functions performed in each function block are implemented by a program executed by the arithmetic unit 720. Alternatively, each function block can be implemented as hardware based on wiring logic.

[0146] like Figure 4 As shown, the arithmetic unit 720 of PLC 710 includes, for example, an input processing unit 721, a measurement unit 722, a driver control unit 723, and a brake control unit 724.

[0147] The input processing unit 721 performs input processing on signals from sensors installed in the injection molding machine 10 that indicate the detection results of those sensors. For example, the input processing unit 711 performs input processing on signals from the opening / closing detector 942 that indicate the opening / closing state of the safety door 941.

[0148] When a predetermined event is detected based on the signal processed by the input processing unit 721, the measurement unit 722 measures the time elapsed since the occurrence of the event. For example, when the safety door 941 is detected to be open, the measurement unit 722 measures the time elapsed since the safety door 941 was opened. Furthermore, this embodiment does not limit the occurrence of the predetermined event to the opening of the safety door 941; for example, it could also be the detection of the emergency stop button 751 being pressed or other abnormal conditions detected by the safety sensors 752.

[0149] The driver control unit 723, triggered by the detection of a predetermined event, performs the following control after a standby time (an example of a second time) has elapsed, based on the measurement results from the measurement unit 722: In order to cut off the power supply to the actuator installed in the injection molding machine 10, the output of the 24V voltage signal is stopped. For example, the case where 100ms has elapsed since the detection of the predetermined event (an example of a second time) is defined as 100ms elapsed since the safety door 941 opened.

[0150] The brake control unit 724, triggered by the detection of a predetermined event, performs the following control after a period equal to the sum of the standby time and the delay time (in an example of the first time), based on the measurement results from the measurement unit 722: In order to perform braking control for the actuator installed in the injection molding machine 10, the output of the 24V voltage signal for the motor brake is stopped. The delay time is set to the time elapsed since the output of the 24V voltage signal was stopped for power cut-off, for example, 50ms. That is, if 150ms has elapsed since the detection of the predetermined event, the following control is performed: the output of the 24V voltage signal for the motor brake is stopped.

[0151] Furthermore, this embodiment illustrates the following example: Braking control begins after a period equal to the sum of the standby time and the delay time, triggered by the detection of a predetermined event. However, in this embodiment, the trigger point for determining the occurrence of the predetermined event is not limited to the moment the predetermined event is detected. For example, braking control can begin after a delay time, triggered by a power cut-off.

[0152] Figure 5This is a timing diagram of power cut-off and braking control based on motor brake 222 when the safety door 941 is open in the injection molding machine 10 according to this embodiment.

[0153] like Figure 5 As shown in line 1501, the safety door 941 is open at time t1. The opening / closing detector 942 outputs a signal to the control device 700 and PLC 710 indicating that the safety door 941 is open. When the input processing unit 711 of the control device 700 processes the signal, the speed control unit 712 begins to control the motor driver (e.g., motor driver 221A) by reducing the speed of the actuator (e.g., ejector motor 221).

[0154] On the other hand, in PLC 710, at the moment when the input processing unit 711 processes the signal, the measuring unit 722 measures the elapsed time since the safety door 941 opened. Furthermore, at time t2, when a standby time (e.g., 100ms) has elapsed since time t1, the driver control unit 723 stops outputting the 24V voltage signal and cuts off the power supply to the actuator (e.g., ejector motor 221) installed in the injection molding machine 10. Therefore, as shown in line 1502, the power cut-off becomes on at time t2.

[0155] Furthermore, in PLC 710, at time t3, after a delay time (e.g., 50 ms) has elapsed since time t2, the brake control unit 724 stops outputting the 24V voltage signal and performs braking control based on the brake installed in the injection molding machine 10 (e.g., the motor brake 222 installed in the ejector motor 221). Therefore, as shown in line 1503, at time t3, the motor brake 222 switches from open to braking.

[0156] The PLC 710 described in this embodiment stores standby time and delay time in a (not shown) storage unit. Furthermore, when executing a program in the arithmetic unit 720, the aforementioned control is performed with reference to the standby time and delay time stored in the storage unit. The standby time and delay time can also be set by the user.

[0157] In this embodiment, control is performed sequentially according to the power cut-off and braking based on the motor brake 222, thus reducing wear on the motor brake 222. In this embodiment, the delay time between power cut-off and the start of braking control based on the motor brake 222 is specified as being minimized as possible while operating sequentially. That is, in this embodiment, the delay time is not limited to 50ms as long as power cut-off and braking control are operated sequentially while minimizing the time between them.

[0158] Furthermore, in this embodiment, when the safety door 941 is opened, the speed of the ejector motor 221 is reduced by the control device 700, and after a standby time has elapsed since the opening was detected, power is cut off based on the PLC 710. By cutting off power after the speed of the ejector motor 221 decreases, the moving speed of the ejector device 200 after the power is cut off can be reduced, and the wear of the motor brake 222 caused by subsequent braking control can be reduced.

[0159] Furthermore, in this embodiment, even without speed reduction control via the control device 700, the PLC 710 performs power cut-off and brake-based braking control in the aforementioned sequence. That is, even if the control device 700 does not operate as intended, the PLC 710 stops the ejector motor 221 by performing power cut-off and brake-based braking control. Thus, the PLC 710 in this embodiment performs power cut-off and braking control regardless of whether the speed of the ejector motor 221 is reduced via the control device 700, thereby improving the reliability of stopping the ejector motor 221. Therefore, improved safety can be achieved.

[0160] This embodiment describes an example of combining control of reducing the speed of the ejector motor 221 via control device 700 with power cut-off based on PLC 710 and brake control based on brake. However, this embodiment is not limited to the combination of control of reducing the speed of the ejector motor 221 via control device 700 with power cut-off based on PLC 710 and brake control based on brake. For example, it is also possible to perform only power cut-off based on PLC 710 and brake control without controlling the speed of the ejector motor 221 via control device 700.

[0161] In this embodiment, an example has been described in which the power cut-off structure (motor driver and actuator) and the braking control structure (motor brake) are separately provided. However, this embodiment is not limited to the example in which the power cut-off structure and the braking control structure are separately provided. The power cut-off structure and the braking control structure can be integrated into one unit.

[0162] (Second Implementation)

[0163] In the first embodiment, the case where the PLC710 directly controls the motor brake 222 and the motor driver (e.g., motor driver 221A) was described. However, the first embodiment is not limited to the method of directly controlling the motor brake 222 and the motor driver (e.g., motor driver 221A). Therefore, in the second embodiment, the case of control via a relay will be described.

[0164] Figure 6 This diagram illustrates an example of the electrical structure of the PLC710 according to this embodiment. (As shown...) Figure 6 As shown, similarly to the first embodiment, the PLC 710 includes an input unit 731, an output unit 732, an arithmetic unit 720, and a memory 730. In this embodiment, the same symbols are assigned to the same structures as in the first embodiment, and the description is omitted.

[0165] In this embodiment, a relay 1601 is provided between the PLC 710 and the ejector motor 221 and the motor driver 221A. Furthermore, a relay 1602 is provided between the PLC 710 and the motor brake 222.

[0166] Furthermore, the motor driver 221A is connected to the 24V power supply 1603 via the relay 1601. When the PLC 710 outputs a 24V voltage signal, current flows through the coil 1601A inside the relay 1601, generating a magnetic field. This magnetic field (not shown) causes an iron plate to contact the contacts, thereby supplying power from the 24V power supply 1603 to the motor driver 221A.

[0167] Furthermore, the motor brake 222 is connected to the 24V power supply 1604 via relay 1602. When the PLC 710 outputs a 24V voltage signal, current flows through the coil 1602A inside the relay 1602, generating a magnetic field. This magnetic field (not shown) causes an iron plate to contact the contacts, thereby supplying power from the 24V power supply 1604 to the motor brake 222.

[0168] That is, as shown in this embodiment, even when relays 1601 and 1602 are provided, PLC 710 performs the same control as in the first embodiment, thereby enabling control of motor driver 221A and motor brake 222.

[0169] The PLC 710 in this embodiment is connected to the motor driver 221A and the motor brake 222 via relays 1601 and 1602. Therefore, in the event of an overcurrent in the motor driver 221A or the motor brake 222, the relays 1601 and 1602 can suppress the impact of the overcurrent on the PLC 710. Thus, the safety of the PLC 710 can be improved.

[0170] (Modified Example)

[0171] In the above embodiments, the case where the injection molding machine 10 is a horizontal machine has been described. However, the above embodiments are not limited to the case where the injection molding machine 10 is a horizontal machine, and a vertical machine can also be used. Therefore, the case where a vertical machine is used will be described.

[0172] Injection molding machines are designed to prevent movement caused by gravity in accordance with safety standards (ISO20430 (JIS B6711)). That is, as a variation, when a vertical machine is used as the injection molding machine 10, when the movable part that can move in the direction of gravity (e.g., mold opening and closing, mold thickness movement, injection device movement) is moved, a braking device (e.g., a motor brake) is required to prevent movement caused by gravity.

[0173] Furthermore, as in the past, if power cut-off and braking control based on a brake used to stop the actuator are performed by different control devices, a significant amount of energy needs to be stopped due to the time difference between power cut-off and brake-based braking control. Therefore, it is necessary to perform power cut-off and braking control at the appropriate time.

[0174] Therefore, in this modified example, similar to the embodiment described above, the PLC 710 sequentially executes the following actions at predetermined times for the movement of the movable part of the vertical injection molding machine: cutting off the power to the actuator that actuates the movable part; and braking control using the motor brake. In this modified example, compared to using an analog delay circuit, more precise timing control can be performed, thus improving safety.

[0175] <Function>

[0176] The PLC710 described in the above embodiments and variations can perform the control described above in a manner that maintains the sequence of power cut-off for the actuator that actuates the movable part and braking control that stops the actuator. Therefore, power cut-off after braking control can be suppressed, thereby suppressing wear on the brake.

[0177] Furthermore, the PLC710 can control the timing of power cut-off and braking control, thus preventing deviations in the timing of braking control from causing loads on the components of the injection molding machine 10.

[0178] In the above embodiments and variations, the arithmetic unit 720, which is configured as a digital circuit, performs power cut-off and braking control according to a pre-made program. Therefore, compared with the case of using an analog delay circuit, it is possible to perform timing control with high precision.

[0179] Furthermore, the PLC 710 described in the above embodiments and variations achieves multiplexing / redundancy in its input unit 731 and output unit 732 through the use of a safety PLC, and performs self-diagnosis through a self-test function, thereby improving safety. Specifically, since the input unit 731 and output unit 732 are multiplexed / redundant, the reliability of stopping the movable part of the injection molding machine 10 according to a pre-made program can be improved, thereby improving safety.

[0180] The above describes an example of a PLC (control device) installed in an injection molding machine and an embodiment of the injection molding machine according to the present invention. However, the present invention is not limited to the above-described embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations can be made within the scope described in the technical solution. These, of course, also fall within the technical scope of the present invention.

Claims

1. A control device for an injection molding machine, comprising: The digital circuit, upon receiving a signal indicating that a predetermined event has been detected from the detection unit of an injection molding machine equipped with a motor that supplies power for moving a movable part and a brake for the motor, sequentially controls the output of a first signal to cut off the power supply to the motor and the output of a second signal to start braking based on the brake.

2. The control device for the injection molding machine according to claim 1, wherein, Upon detecting the occurrence of a specified event, the digital circuit controls the output of the second signal after a first time interval following the control of the output of the first signal.

3. The control device for the injection molding machine according to claim 1, wherein, Upon detecting the occurrence of a predetermined event, the digital circuit controls the output of the first signal after a second time interval.

4. An injection molding machine, comprising: A motor provides the power to move the movable part. The brake of the motor; and Upon receiving a signal indicating that a predetermined event has been detected, the control device sequentially controls the output of a first signal to cut off the power supply to the motor and the output of a second signal to start braking based on the brake.

5. The injection molding machine according to claim 4, wherein, The motor is an ejector motor that drives the ejector installed in the injection molding machine, a mold closing motor that performs mold closing in the mold device installed in the injection molding machine, an injection motor that moves the screw installed in the cylinder of the injection molding machine forward and backward, a mold thickness adjustment motor that adjusts the gap between the fixed pressure plate and the toggle seat installed in the injection molding machine, or an injection molding machine movement motor that moves the injection molding machine from the frame.

6. The injection molding machine according to claim 4, wherein, A relay is provided between the control device and the brake, and a relay is also provided between the control device and the motor.

Images