Control device of injection molding machine, and injection molding machine

Abstract

To improve safety.SOLUTION: A control device of an injection molding machine according to an embodiment includes a digital circuit that sequentially controls an output of a first signal for performing power cutoff for cutting off power supply to a motor and an output of a second signal for starting braking by a brake when a signal indicating that occurrence of a predetermined event is detected is received from a detection unit provided in the injection molding machine including the motor that supplies power for moving a movable part and the brake for the motor.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a control device for an injection molding machine and an injection molding machine. [Background technology]

[0002] Conventionally, various controls have been implemented to ensure safety when operating injection molding machines. For example, Patent Document 1 discloses an injection molding machine equipped with a safety door, a detector that detects the open / closed state of the safety door, and a controller that stops a drive unit based on the detection result of the detector. When the safety door is opened, the controller of this injection molding machine switches over a switch to de-energize the coil of a relay switch that operates the motor drive unit of the mold clamping mechanism, thereby stopping the motor drive unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-230113 Summary of the Invention [Problem to be solved by the invention]

[0004] In actual injection molding machines, when stopping a moving part, power to the actuator that operates the moving part tends to be cut off and braking control using a brake to stop the actuator. In actual injection molding machines, the power cut off and braking control are performed by different devices. Because these are performed by different devices, it was difficult to adjust the order of power cut off and braking control so that they operate with high precision when stopping the moving part.

[0005] One aspect of the present invention provides a technique for improving safety by improving the reliability of power cutoff and braking control being performed in that order. [Means for solving the problem]

[0006] A control device for an injection molding machine according to one embodiment of the present invention includes a digital circuit that, when receiving a signal indicating that a predetermined event has occurred from a detection unit provided in an injection molding machine having a motor that supplies power to move a movable part and a brake for the motor, sequentially controls the output of a first signal to cut off power supply to the motor and the output of a second signal to start braking by the brake. [Effects of the Invention]

[0007] According to one aspect of the present invention, the reliability of power cutoff and braking control being performed in that order is improved, thereby improving safety. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a state when mold opening of an injection molding machine according to one embodiment is completed. [Figure 2] FIG. 2 is a diagram showing a state of the injection molding machine according to one embodiment when clamping the mold. [Figure 3] FIG. 3 is a diagram illustrating an example of the electrical configuration of the PLC according to the first embodiment. [Figure 4] FIG. 4 is a functional configuration diagram showing the main configuration of the control device and the PLC according to the first embodiment. [Figure 5] FIG. 5 is a timing chart of the power cutoff and braking control by the brake that is performed when the safety door is opened in the injection molding machine according to the first embodiment. [Figure 6] FIG. 6 is a diagram illustrating an example of the electrical configuration of the PLC according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments described below are merely examples and do not limit the invention, and all features and combinations described in the embodiments are not necessarily essential to the invention. In addition, identical or corresponding components in each drawing are designated by identical or corresponding reference numerals, and descriptions thereof may be omitted.

[0010] FIG. 1 is a diagram showing the state of the injection molding machine according to the first embodiment when mold opening is completed. FIG. 2 is a diagram showing the state of the injection molding machine according to the first embodiment when mold clamping is performed. In this specification, the X-axis direction, Y-axis direction, and Z-axis direction are perpendicular to each other. The X-axis direction and Y-axis direction represent horizontal directions, and the Z-axis direction represents vertical directions. When the mold clamping device 100 is of a horizontal type, the X-axis direction is the mold opening / closing direction, and the Y-axis direction is the width direction of the injection molding machine 10. The negative side of the Y-axis direction is called the operating side, and the positive side of the Y-axis direction is called the counter-operating side.

[0011] As shown in FIGS. 1 and 2 , injection molding machine 10 includes a mold clamping unit 100 that opens and closes mold apparatus 800, an ejector unit 200 that ejects a molded product molded by mold apparatus 800, an injection unit 300 that injects molding material into mold apparatus 800, a moving unit 400 that moves injection unit 300 forward and backward relative to mold apparatus 800, a control unit 700 that controls each component of injection molding machine 10, and a frame 900 that supports each component of injection molding machine 10. Frame 900 includes a mold clamping unit frame 910 that supports mold clamping unit 10 and an injection unit frame 920 that supports injection unit 300. Clamping unit frame 910 and injection unit frame 920 are each installed on floor 2 via leveling adjusters 930. Control unit 700 is disposed in the interior space of injection unit frame 920. Each component of injection molding machine 10 will be described below.

[0012] (mold clamping device) In the description of the mold clamping unit 100, the moving direction of the movable platen 120 during mold closing (for example, the positive X-axis direction) is defined as the front, and the moving direction of the movable platen 120 during mold opening (for example, the negative X-axis direction) is defined as the rear.

[0013] The mold clamping unit 100 performs mold closing, pressurization, mold clamping, depressurization, and mold opening of the mold device 800. The mold device 800 includes a fixed mold 810 and a movable mold 820. The mold clamping unit 100 is, for example, a horizontal type, and the mold opening and closing direction is horizontal. The mold clamping unit 100 has a fixed platen 110 to which the fixed mold 810 is attached, a movable platen 120 to which the movable mold 820 is attached, and a movement mechanism 102 that moves the movable platen 120 in the mold opening and closing direction relative to the fixed platen 110.

[0014] The stationary platen 110 is fixed to the mold clamping unit frame 910. A stationary mold 810 is attached to the surface of the stationary platen 110 that faces the movable platen 120.

[0015] The movable platen 120 is disposed so as to be movable in the mold opening / closing direction relative to the mold clamping unit frame 910. A guide 101 for guiding the movable platen 120 is installed on the mold clamping unit frame 910. A movable mold 820 is attached to the surface of the movable platen 120 facing the fixed platen 110.

[0016] The moving mechanism 102 moves the movable platen 120 forward and backward relative to the fixed platen 110, thereby performing mold closing, pressurization, mold clamping, depressurization, and mold opening of the mold apparatus 800. The moving mechanism 102 has a toggle support 130 arranged at a distance from the fixed platen 110, tie bars 140 connecting the fixed platen 110 and the toggle support 130, a toggle mechanism 150 that moves the movable platen 120 in the mold opening / closing direction relative to the toggle support 130, 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 platen 110 and the toggle support 130.

[0017] The toggle support 130 is disposed at a distance from the fixed platen 110 and is placed on the mold clamping unit frame 910 so as to be freely movable in the mold opening and closing direction. The toggle support 130 may be disposed so as to be freely movable along a guide laid on the mold clamping unit frame 910. The guide of the toggle support 130 may be the same as the guide 101 of the movable platen 120.

[0018] In this embodiment, the fixed platen 110 is fixed to the mold clamping unit frame 910, and the toggle support 130 is arranged so as to be freely movable in the mold opening and closing direction relative to the mold clamping unit frame 910, but the toggle support 130 may also be fixed to the mold clamping unit frame 910, and the fixed platen 110 may be arranged so as to be freely movable in the mold opening and closing direction relative to the mold clamping unit frame 910.

[0019] The tie bars 140 connect the fixed platen 110 and the toggle support 130 at an interval L in the mold opening / closing direction. A plurality of tie bars 140 (for example, four) may be used. The plurality of tie bars 140 are arranged parallel to the mold opening / closing direction and extend according to the mold clamping force. At least one tie bar 140 may be provided with a tie bar strain detector 141 that detects strain in the tie bar 140. The tie bar strain detector 141 sends a signal indicating the detection result to the control device 700. The detection result of the tie bar strain detector 141 is used to detect the mold clamping force, etc.

[0020] In this embodiment, the tie bar strain detector 141 is used as the mold clamping force detector that detects the mold clamping force, but the present invention is not limited to this. The mold clamping force detector is not limited to the strain gauge type, and may be a piezoelectric type, a capacitance type, a hydraulic type, an electromagnetic type, or the like, and the attachment position thereof is also not limited to the tie bar 140.

[0021] The toggle mechanism 150 is disposed between the movable platen 120 and the toggle support 130 and moves the movable platen 120 relative to the toggle support 130 in the mold opening / closing direction. The toggle mechanism 150 has a crosshead 151 that moves in the mold opening / closing direction and a pair of link groups that bend and extend with the movement of the crosshead 151. Each of the pair of link groups has a first link 152 and a second link 153 that are connected to bendable and extendable by a pin or the like. The first link 152 is attached to the movable platen 120 by a pin or the like so that it can swing freely. The second link 153 is attached to the toggle support 130 by a pin or the like so that it can swing freely. The second link 153 is attached to the crosshead 151 via a third link 154. When the crosshead 151 advances or retreats relative to the toggle support 130, the first link 152 and the second link 153 bend and extend, and the movable platen 120 advances or retreats relative to the toggle support 130.

[0022] The configuration of toggle mechanism 150 is not limited to the configuration shown in Figures 1 and 2. For example, although each link group has five nodes in Figures 1 and 2, it may have four nodes, and one end of third link 154 may be connected to a node between first link 152 and second link 153.

[0023] The mold clamping motor 160 is attached to the toggle support 130 and operates the toggle mechanism 150. The mold clamping motor 160 moves the crosshead 151 forward and backward relative to the toggle support 130, thereby bending and extending the first link 152 and the second link 153 and moving the movable platen 120 forward and backward relative to the toggle support 130. The mold clamping motor 160 is directly connected to the motion conversion mechanism 170, but may also be connected to the motion conversion mechanism 170 via a belt, a pulley, or the like.

[0024] The mold clamping motor 160 has a built-in motor brake 162, which operates to stop the rotation of the motor shaft itself of the mold clamping motor 160. The motor brake 162 is, for example, a non-excitation brake, and operates when the supply of power is stopped.

[0025] The motion conversion mechanism 170 converts the rotational motion of the mold clamping motor 160 into the linear motion of the crosshead 151. The motion conversion mechanism 170 includes a screw shaft and a screw nut that screws onto the screw shaft. A ball or roller may be interposed between the screw shaft and the screw nut.

[0026] The mold clamping unit 100 performs a mold closing process, a pressure increasing process, a mold clamping process, a pressure reducing process, a mold opening process, and the like under the control of the control device 700.

[0027] In the mold closing process, the mold clamping motor 160 is driven to move the crosshead 151 forward at a set movement speed to a mold closing completion position, thereby moving the movable platen 120 forward and bringing the movable mold 820 into contact with the fixed mold 810. The position and movement speed of the crosshead 151 are detected using, for example, a mold clamping motor encoder 161. The mold clamping motor encoder 161 detects the rotation of the mold clamping motor 160 and sends a signal indicating the detection result to the control device 700.

[0028] The crosshead position detector that detects the position of the crosshead 151 and the crosshead movement speed detector that detects the movement speed of the crosshead 151 are not limited to the mold clamping motor encoder 161, and general types can be used. Furthermore, the movable platen position detector that detects the position of the movable platen 120 and the movable platen movement speed detector that detects the movement speed of the movable platen 120 are not limited to the mold clamping motor encoder 161, and general types can be used.

[0029] In the pressure increasing step, the mold clamping motor 160 is further driven to move the crosshead 151 further forward from the mold closing completion position to the mold clamping position, thereby generating a mold clamping force.

[0030] In the mold clamping process, the mold clamping motor 160 is driven to maintain the position of the crosshead 151 at the mold clamping position. In the mold clamping process, the mold clamping force generated in the pressure increase process is maintained. In the mold clamping process, a cavity space 801 (see FIG. 2) is formed between the movable mold 820 and the fixed mold 810, and the injection device 300 fills the cavity space 801 with liquid molding material. The filled molding material is solidified to obtain a molded product.

[0031] The number of cavity spaces 801 may be one or more. In the latter case, multiple molded products are obtained at the same time. An insert material may be placed in a part of the cavity space 801, and another part of the cavity space 801 may be filled with a molding material. A molded product is obtained in which the insert material and the molding material are integrated.

[0032] In the depressurization process, the mold clamping motor 160 is driven to move the crosshead 151 back from the mold clamping position to the mold opening start position, thereby moving the movable platen 120 back and reducing the mold clamping force. The mold opening start position and the mold closing completion position may be the same position.

[0033] In the mold opening process, the mold clamping motor 160 is driven to move the crosshead 151 backward at a set moving speed from the mold opening start position to the mold opening completion position, thereby moving the movable platen 120 backward and separating the movable mold 820 from the fixed mold 810. Thereafter, the ejector unit 200 ejects the molded product from the movable mold 820.

[0034] The setting conditions for the mold closing process, pressure increase process, and mold clamping process are set together as a series of setting conditions. For example, the movement speed and position of the crosshead 151 in the mold closing process and pressure increase process (including the mold closing start position, movement speed switching position, mold closing completion position, and mold clamping position), and the mold clamping force are set together as a series of setting conditions. The mold closing start position, movement speed switching position, mold closing completion position, and mold clamping position are arranged in this order from the rear side to the front, and represent the start and end points of the section for which the movement speed is set. The movement speed is set for each section. There may be one or more movement speed switching positions. The movement speed switching position does not have to be set. Only one of the mold clamping position and the mold clamping force may be set.

[0035] The setting conditions for the depressurization process and mold opening process are also set in a similar manner. For example, the movement speed and position of the crosshead 151 in the depressurization process and mold opening process (mold opening start position, movement speed switching position, and mold opening completion position) are set together as a series of setting conditions. The mold opening start position, movement speed switching position, and mold opening completion position are arranged in this order from the front to the rear, and represent the start and end points of the section for which the movement speed is set. The movement speed is set for each section. There may be one or more movement speed switching positions. The movement speed switching position does not have to be set. The mold opening start position and mold closing completion position may be the same position. Furthermore, the mold opening completion position and mold closing start position may be the same position.

[0036] It should be noted that the moving speed and position of the movable platen 120 may be set instead of the moving speed and position of the crosshead 151. Furthermore, the clamping force may be set instead of the position of the crosshead (for example, the clamping position) or the position of the movable platen.

[0037] The toggle mechanism 150 amplifies the driving force of the mold clamping motor 160 and transmits it to the movable platen 120. The amplification factor is also called the toggle factor. The toggle factor changes depending on the angle θ between the first link 152 and the second link 153 (hereinafter also referred to as the "link angle θ"). The link angle θ is determined from the position of the crosshead 151. When the link angle θ is 180°, the toggle factor is maximum.

[0038] When the thickness of the mold device 800 changes due to replacement of the mold device 800 or a temperature change in the mold device 800, a mold thickness adjustment is performed so that a predetermined clamping force is obtained during mold clamping. In mold thickness adjustment, for example, the distance L between the fixed platen 110 and the toggle support 130 is adjusted so that the link angle θ of the toggle mechanism 150 becomes a predetermined angle at the time of mold touch when the movable mold 820 touches the fixed mold 810.

[0039] The mold clamping unit 100 has a mold thickness adjustment mechanism 180. The mold thickness adjustment mechanism 180 adjusts the mold thickness by adjusting the distance L between the fixed platen 110 and the toggle support 130. The mold thickness adjustment is performed, for example, between the end of a molding cycle and the start of the next molding cycle. The mold thickness adjustment mechanism 180 has, for example, a screw shaft 181 formed at the rear end of the tie bar 140, a screw nut 182 held rotatably and immovably by the toggle support 130, and a mold thickness adjustment motor 183 that rotates the screw nut 182 that is threaded onto the screw shaft 181.

[0040] A screw shaft 181 and a screw nut 182 are provided for each tie bar 140. The rotational driving force of the mold thickness adjustment motor 183 may be transmitted to the plurality of screw nuts 182 via a rotational driving force transmission unit 185. The plurality of screw nuts 182 can be rotated synchronously. Note that by changing the transmission path of the rotational driving force transmission unit 185, the plurality of screw nuts 182 can also be rotated individually.

[0041] The rotational drive force transmission unit 185 is configured with, for example, gears. In this case, a driven gear is formed on the outer periphery of each screw nut 182, a drive gear is attached to the output shaft of the mold thickness adjustment motor 183, and an intermediate gear that meshes with the multiple driven gears and drive gear is rotatably held in the center of the toggle support 130. Note that the rotational drive force transmission unit 185 may be configured with a belt, pulleys, or the like instead of gears.

[0042] The operation of the mold thickness adjustment mechanism 180 is controlled by a control device 700. The control device 700 drives a mold thickness adjustment motor 183 to rotate the screw nut 182. As a result, the position of the toggle support 130 relative to the tie bar 140 is adjusted, and the distance L between the fixed platen 110 and the toggle support 130 is adjusted. Note that a plurality of mold thickness adjustment mechanisms may be used in combination.

[0043] The gap L is detected using a mold thickness adjustment motor encoder 184. The mold thickness adjustment motor encoder 184 detects the amount and direction of rotation of the mold thickness adjustment motor 183, and sends a signal indicating the detection result to the control device 700. The detection result of the mold thickness adjustment motor encoder 184 is used to monitor and control the position of the toggle support 130 and the gap L. Note that the toggle support position detector that detects the position of the toggle support 130 and the gap detector that detects the gap L are not limited to the mold thickness adjustment motor encoder 184, and general detectors can be used.

[0044] The mold thickness adjustment motor 183 has a built-in motor brake 186, which operates to stop the rotation of the motor shaft itself of the mold thickness adjustment motor 183. The motor brake 186 is, for example, a non-excitation brake, and operates when the supply of power is stopped.

[0045] The mold clamping unit 100 may have a mold temperature regulator that regulates the temperature of the mold device 800. The mold device 800 has a flow path for a temperature regulation medium inside. The mold temperature regulator regulates the temperature of the mold device 800 by regulating the temperature of the temperature regulation medium supplied to the flow path of the mold device 800.

[0046] Although the mold clamping unit 100 of this embodiment is a horizontal type in which the mold opening and closing direction is horizontal, it may also be a vertical type in which the mold opening and closing direction is vertical.

[0047] Although the mold clamping unit 100 of this embodiment has a mold clamping motor 160 as a drive source, it may have a hydraulic cylinder instead of the mold clamping motor 160. Also, the mold clamping unit 100 may have a linear motor for opening and closing the mold, and an electromagnet for mold clamping.

[0048] (Ejector device) In describing the ejector device 200, similar to the description of the mold clamping device 100, the direction of movement of the movable platen 120 when the mold is closed (e.g., the positive direction of the X-axis) is defined as the front, and the direction of movement of the movable platen 120 when the mold is opened (e.g., the negative direction of the X-axis) is defined as the rear.

[0049] The ejector unit 200 is attached to the movable platen 120 and moves forward and backward together with the movable platen 120. The ejector unit 200 has an ejector rod 210 that ejects a molded product from the mold device 800, and a drive mechanism 220 that moves the ejector rod 210 in the movement direction of the movable platen 120 (X-axis direction).

[0050] The ejector rod 210 is arranged so as to be able to move forward and backward in a through-hole of the movable platen 120. The front end of the ejector rod 210 contacts an ejector plate 826 of the movable mold 820. The front end of the ejector rod 210 may or may not be connected to the ejector plate 826.

[0051] 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 screw shaft and a screw nut that screws onto the screw shaft. A ball or roller may be interposed between the screw shaft and the screw nut.

[0052] The ejector unit 200 performs an ejection process under the control of the control unit 700. In the ejection process, the ejector rod 210 advances from the standby position to the ejection position at a set moving speed, thereby advancing the ejector plate 826 and ejecting the molded product. Thereafter, the ejector motor 221 is driven to retract the ejector rod 210 at a set moving speed, and the ejector plate 826 is retracted to the original standby position.

[0053] The position and movement speed of the ejector rod 210 are detected using, for example, an ejector motor encoder. The ejector motor encoder detects the rotation of the ejector motor 221 and sends a signal indicating the detection result to the control device 700. Note that the ejector rod position detector that detects the position of the ejector rod 210 and the ejector rod movement speed detector that detects the movement speed of the ejector rod 210 are not limited to the ejector motor encoder, and general types can be used.

[0054] The ejector motor 221 has a built-in motor brake 222, which operates to stop the rotation of the motor shaft itself of the ejector motor 221. The motor brake 222 is, for example, a non-excitation brake, and operates when the supply of power is stopped.

[0055] (injection device) In the description of the injection device 300, unlike the description of the mold clamping device 100 and the description of the ejector device 200, the movement direction of the screw 330 during filling (e.g., the negative X-axis direction) is described as the forward direction, and the movement direction of the screw 330 during metering (e.g., the positive X-axis direction) is described as the rearward direction.

[0056] The injection unit 300 is mounted on a slide base 301, and the slide base 301 is disposed so as to be able to move forward and backward relative to the injection unit frame 920. The injection unit 300 is disposed so as to be able to move forward and backward relative to the mold unit 800. The injection unit 300 touches the mold unit 800 and fills the molding material measured in a cylinder 310 into a cavity space 801 in the mold unit 800. The injection unit 300 includes, for example, a cylinder 310 that heats the molding material, a nozzle 320 provided at the front end of the cylinder 310, a screw 330 that is disposed so as to be able to move forward and backward and to be able to rotate within the cylinder 310, a metering motor 340 that rotates the screw 330, an injection motor 350 that moves the screw 330 forward and backward, and a load detector 360 that detects the load transmitted between the injection motor 350 and the screw 330.

[0057] Cylinder 310 heats the molding material supplied to the interior through supply port 311. The molding material includes, for example, resin. The molding material is formed, for example, in the form of pellets, and is supplied to supply port 311 in a solid state. Supply port 311 is formed at the rear of cylinder 310. A cooler 312, such as a water-cooled cylinder, is provided on the outer periphery of the rear of cylinder 310. A heater 313, such as a band heater, and a temperature detector 314 are provided on the outer periphery of cylinder 310, ahead of cooler 312.

[0058] Cylinder 310 is divided into a plurality of zones in the axial direction (e.g., X-axis direction) of cylinder 310. Each of the plurality of zones is provided with a heater 313 and a temperature detector 314. A set temperature is set for each of the plurality of zones, and control device 700 controls heater 313 so that the temperature detected by temperature detector 314 becomes the set temperature.

[0059] The nozzle 320 is provided at the front end of the cylinder 310 and is pressed against the mold device 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.

[0060] The screw 330 is disposed within the cylinder 310 so as to be rotatable and movable forward and backward. When the screw 330 is rotated, the molding material is sent forward along the spiral groove of the screw 330. As the molding material is sent forward, it is gradually melted by the heat from the cylinder 310. As the liquid molding material is sent forward to the front of the screw 330 and accumulates in the front part of the cylinder 310, the screw 330 is moved backward. Thereafter, when the screw 330 is moved forward, the liquid molding material accumulated in front of the screw 330 is injected from the nozzle 320 and filled into the mold device 800.

[0061] A backflow prevention ring 331 is attached to the front of the screw 330 so as to be movable back and forth as a backflow prevention valve for preventing the molding material from flowing back from the front to the rear of the screw 330 when the screw 330 is pushed forward.

[0062] When the screw 330 is moved forward, the backflow prevention ring 331 is pushed backward by the pressure of the molding material in front of the screw 330, and moves back relative to the screw 330 to a blocking position (see FIG. 2) where it blocks the flow path of the molding material. This prevents the molding material accumulated in front of the screw 330 from flowing backward.

[0063] On the other hand, when the screw 330 is rotated, the backflow prevention ring 331 is pushed forward by the pressure of the molding material sent forward along the spiral groove of the screw 330, and moves forward relative to the screw 330 to the open position (see FIG. 1) where it opens the flow path of the molding material. This causes the molding material to be sent forward of the screw 330.

[0064] The backflow prevention ring 331 may be either a co-rotating type that rotates together with the screw 330 or a non-co-rotating type that does not rotate together with the screw 330.

[0065] The injection device 300 may have a drive source for moving the backflow prevention ring 331 back and forth relative to the screw 330 between the open position and the closed position.

[0066] The metering motor 340 rotates the screw 330. The drive source for rotating the screw 330 is not limited to the metering motor 340, and may be, for example, a hydraulic pump.

[0067] The injection motor 350 advances and retreats the screw 330. A motion conversion mechanism that converts the rotational motion of the injection motor 350 into linear motion of the screw 330 is provided between the injection motor 350 and the screw 330. The motion conversion mechanism has, for example, a screw shaft and a screw nut that screws onto the screw shaft. A ball or roller may be provided between the screw shaft and the screw nut. The drive source that advances and retreats the screw 330 is not limited to the injection motor 350 and may be, for example, a hydraulic cylinder.

[0068] The injection motor 350 has a built-in motor brake 352 that operates to stop the rotation of the motor shaft itself of the injection motor 350. The motor brake 352 is, for example, a non-excitation brake that operates when the supply of power (signal) is stopped.

[0069] The load detector 360 detects the load transmitted between the injection motor 350 and the screw 330. The detected load is converted into pressure by the control device 700. The load detector 360 is provided on the load transmission path between the injection motor 350 and the screw 330, and detects the load acting on the load detector 360.

[0070] The load detector 360 sends a signal of the detected load to the control device 700. The load detected by the load detector 360 is converted into pressure acting between the screw 330 and the molding material, and is used to control and monitor the pressure that the screw 330 receives from the molding material, the back pressure on the screw 330, the pressure that the screw 330 acts on the molding material, and the like.

[0071] The pressure detector for detecting the pressure of the molding material is not limited to the load detector 360, and a general detector may be used. For example, a nozzle pressure sensor or a mold internal pressure sensor may be used. The nozzle pressure sensor is installed in the nozzle 320.

[0072] The injection device 300 performs a metering process, a filling process, a pressure holding process, etc. under the control of the control device 700. The filling process and the pressure holding process may be collectively referred to as the injection process.

[0073] In the metering process, the metering motor 340 is driven to rotate the screw 330 at a set rotational speed, and the molding material is sent forward along the spiral groove of the screw 330. As this happens, the molding material gradually melts. As the liquid molding material is sent forward to the screw 330 and accumulates at the front of the cylinder 310, the screw 330 is moved backward. The rotational speed of the screw 330 is detected, for example, using a metering motor encoder 341. The metering motor encoder 341 detects the rotation of the metering motor 340 and sends a signal indicating the detection result to the control device 700. Note that the screw rotational speed detector that detects the rotational speed of the screw 330 is not limited to the metering motor encoder 341, and a general one can be used.

[0074] In the metering process, in order to restrict abrupt retraction of the screw 330, the injection motor 350 may be driven to apply a set back pressure to the screw 330. The back pressure on the screw 330 is detected using, for example, a load detector 360. When the screw 330 retracts to the metering completion position and a predetermined amount of molding material accumulates in front of the screw 330, the metering process is completed.

[0075] The position and rotational speed of the screw 330 in the metering process are set together as a series of setting conditions. For example, a metering start position, a rotational speed switching position, and a metering completion position are set. These positions are arranged in this order from the front to the rear, and represent the start and end points of the section for which the rotational speed is set. The rotational speed is set for each section. There may be one or more rotational speed switching positions. The rotational speed switching position does not have to be set. In addition, a back pressure is set for each section.

[0076] In the filling process, the injection motor 350 is driven to move the screw 330 forward at a set moving speed, and the liquid molding material accumulated in front of the screw 330 is filled into the cavity space 801 in the mold device 800. The position and moving speed of the screw 330 are detected using, for example, an injection motor encoder 351. The injection motor encoder 351 detects the rotation of the injection motor 350 and sends a signal indicating the detection result to the control device 700. When the position of the screw 330 reaches a set position, a switch from the filling process to a pressure holding process (so-called V / P switch) is performed. The position at which the V / P switch is performed is also called the V / P switch position. The set moving speed of the screw 330 may be changed depending on the position of the screw 330, time, etc.

[0077] The position and movement speed of the screw 330 in the filling process are set together as a series of setting conditions. For example, a filling start position (also called an "injection start position"), a movement speed switching position, and a V / P switching position are set. These positions are arranged in this order from rear to front, and represent the start and end points of the section for which the movement speed is set. The movement speed is set for each section. There may be one or more movement speed switching positions. The movement speed switching position does not have to be set.

[0078] An upper limit value for the pressure of the screw 330 is set for each section in which the movement speed of the screw 330 is set. The pressure of the screw 330 is detected by a load detector 360. When the pressure of the screw 330 is equal to or lower than the set pressure, the screw 330 is advanced at the set movement speed. On the other hand, when the pressure of the screw 330 exceeds the set pressure, the screw 330 is advanced at a movement speed slower than the set movement speed so that the pressure of the screw 330 is equal to or lower than the set pressure, in order to protect the mold.

[0079] Note that after the position of the screw 330 reaches the V / P switching position during the filling process, the screw 330 may be temporarily stopped at the V / P switching position, and then V / P switching may be performed. Immediately before V / P switching, instead of stopping the screw 330, the screw 330 may be moved forward or backward at a slow speed. Furthermore, the screw position detector that detects the position of the screw 330 and the screw movement speed detector that detects the movement speed of the screw 330 are not limited to the injection motor encoder 351, and general detectors may be used.

[0080] In the dwelling step, the injection motor 350 is driven to push 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 molding material remaining in the cylinder 310 toward the mold device 800. This can replenish any molding material that is insufficient due to cooling contraction within the mold device 800. The holding pressure is detected, for example, using a load detector 360. The set value of the holding pressure may be changed depending on the elapsed time from the start of the dwelling step, etc. Multiple holding pressures and holding times for maintaining the holding pressure in the dwelling step may be set, or they may be set together as a series of setting conditions.

[0081] In the dwelling step, the molding material in the cavity space 801 in the mold device 800 is gradually cooled, and when the dwelling step is completed, the entrance to the cavity space 801 is blocked by the solidified molding material. This state is called a gate seal, and prevents the molding material from flowing back from the cavity space 801. After the dwelling step, the cooling step begins. In the cooling step, the molding material in the cavity space 801 is solidified. A metering step may be performed during the cooling step in order to shorten the molding cycle time.

[0082] The injection device 300 of this embodiment is of an in-line screw type, but may also be of a pre-plasticization type. A pre-plasticization type injection device supplies molding material molten in a plasticization cylinder to an injection cylinder, and injects the molding material from the injection cylinder into a mold device. A screw is disposed in the plasticization cylinder so that it can rotate freely but cannot move back and forth, or the screw is disposed so that it can rotate freely and move back and forth. Meanwhile, a plunger is disposed in the injection cylinder so that it can move back and forth.

[0083] Furthermore, although the injection unit 300 of this embodiment is a horizontal type in which the axial direction of the cylinder 310 is horizontal, it may be a vertical type in which the axial direction of the cylinder 310 is vertical. The mold clamping unit combined with the vertical injection unit 300 may be either a vertical type or a horizontal type. Similarly, the mold clamping unit combined with the horizontal injection unit 300 may be either a horizontal type or a vertical type.

[0084] (Mobile device) In the description of the moving device 400, similar to the description of the injection device 300, the moving direction of the screw 330 during filling (e.g., the negative X-axis direction) is defined as the front, and the moving direction of the screw 330 during metering (e.g., the positive X-axis direction) is defined as the rear.

[0085] The moving device 400 moves the injection device 300 forward and backward relative to the mold device 800. The moving device 400 also presses the nozzle 320 against the mold device 800 to generate nozzle touch pressure. The moving device 400 includes a hydraulic pump 410, a motor 420 as a drive source, a hydraulic cylinder 430 as a hydraulic actuator, and the like.

[0086] The hydraulic pump 410 has a first port 411 and a second port 412. The hydraulic pump 410 is a bidirectional pump, and by switching the rotation direction of the motor 420, it draws in hydraulic fluid (e.g., oil) from one of the first port 411 and the second port 412 and discharges it from the other, thereby generating hydraulic pressure. Note that the hydraulic pump 410 can also draw in hydraulic fluid from a tank and discharge it from either the first port 411 or the second port 412.

[0087] The motor 420 operates the hydraulic pump 410. The motor 420 drives the hydraulic pump 410 in a rotational direction and with a rotational torque according to a control signal from the control device 700. The motor 420 may be an electric motor or an electric servo motor.

[0088] The hydraulic cylinder 430 has a cylinder body 431, a piston 432, and a piston rod 433. The cylinder body 431 is fixed to the injection device 300. The piston 432 divides the interior of the cylinder body 431 into a front chamber 435 as a first chamber and a rear chamber 436 as a second chamber. The piston rod 433 is fixed to the fixed platen 110.

[0089] A front chamber 435 of the hydraulic cylinder 430 is connected to a first port 411 of the hydraulic pump 410 via a first flow path 401. The hydraulic fluid discharged from the first port 411 is supplied to the front chamber 435 via the first flow path 401, thereby pushing the injection unit 300 forward. The injection unit 300 is moved forward, and the nozzle 320 is pressed against the fixed mold 810. The front chamber 435 functions as a pressure chamber that generates nozzle touch pressure of the nozzle 320 by the pressure of the hydraulic fluid supplied from the hydraulic pump 410.

[0090] Meanwhile, 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 hydraulic fluid discharged 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 unit 300 backward. The injection unit 300 is moved backward, and the nozzle 320 is separated from the fixed mold 810.

[0091] In this embodiment, the moving device 400 includes the hydraulic cylinder 430, but the present invention is not limited to this. 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 be used.

[0092] (Control device) The control device 700 is configured, for example, by a computer, and has a CPU (Central Processing Unit) 701, a storage medium 702 such as a memory, an input interface 703, an output interface 704, and a communication interface 705, as shown in Figures 1 and 2. The control device 700 performs various controls by causing the CPU 701 to execute a program stored in the storage medium 702. The control device 700 also receives signals from the outside via the input interface 703 and transmits signals to the outside via the output interface 704.

[0093] The control device 700 repeatedly produces molded products by repeating processes such as a metering process, mold closing process, pressure increase process, mold clamping process, filling process, pressure dwell process, cooling process, pressure release process, mold opening process, and ejection process. A series of operations required to obtain a molded product, for example, the operations from the start of a metering process to the start of the next metering process, is also called a "shot" or "molding cycle." The time required for one shot is also called the "molding cycle time" or "cycle time."

[0094] One molding cycle includes, for example, a metering process, a mold closing process, a pressurization process, a mold clamping process, a filling process, a pressure holding process, a cooling process, a depressurization process, a mold opening process, and an ejection process, in this order. The order here refers to the order in which each process starts. The filling process, the pressure holding process, and the cooling process are performed during the mold clamping process. The start of the mold clamping process may coincide with the start of the filling process. The completion of the depressurization process coincides with the start of the mold opening process.

[0095] In addition, multiple processes may be performed simultaneously in order to shorten the molding cycle time. For example, the metering process may be performed during the cooling process of the previous molding cycle, or during the mold clamping process. In this case, the mold closing process may be performed at the beginning of the molding cycle. The filling process may be started during the mold closing process. The ejection process may be started during the mold opening process. If an on-off valve that opens and closes the flow path of the nozzle 320 is provided, the mold opening process may be started during the metering process. This is because even if the mold opening process is started during the metering process, the molding material will not leak from the nozzle 320 as long as the on-off valve closes the flow path of the nozzle 320.

[0096] Note that one molding cycle may include steps other than the metering step, mold closing step, pressure increase step, mold clamping step, filling step, pressure holding step, cooling step, pressure release step, mold opening step, and ejection step.

[0097] For example, after the dwelling step is completed and before the metering step begins, a pre-metering suck-back step may be performed in which the screw 330 is retracted to a preset metering start position. This can reduce the pressure of the molding material accumulated in front of the screw 330 before the metering step begins, and prevent the screw 330 from retracting suddenly at the start of the metering step.

[0098] Furthermore, after the metering step is completed and before the filling step begins, a post-metering suck-back step may be performed in which the screw 330 is retracted to a preset filling start position (also referred to as the "injection start position"). This can reduce the pressure of the molding material accumulated in front of the screw 330 before the filling step begins, and can prevent the molding material from leaking from the nozzle 320 before the filling step begins.

[0099] The control device 700 is connected to an operation device 750 that accepts input operations by a user and a display device 760 that displays a screen. The operation device 750 and the display device 760 may be integrated, for example, and configured as a touch panel 770. The touch panel 770 serving as the display device 760 displays a screen under the control of the control device 700. The screen of the touch panel 770 may display information, such as settings of the injection molding machine 10 and the current status of the injection molding machine 10. The touch panel 770 is capable of accepting operations in the displayed screen area. Furthermore, the screen area of ​​the touch panel 770 may display operation units, such as buttons and input fields, that accept input operations by the user. The touch panel 770 serving as the operation device 750 detects input operations on the screen by the user and outputs a signal corresponding to the input operation to the control device 700. This allows, for example, a user to operate the operation unit provided on the screen while checking the information displayed on the screen to perform settings of the injection molding machine 10 (including input of setting values), etc. Furthermore, by operating an operation unit provided on the screen, the user can cause the injection molding machine 10 to perform an operation corresponding to the operation unit. Note that the operation of the injection molding machine 10 may be, for example, the operation (including stopping) of the mold clamping unit 100, the ejector unit 200, the injection unit 300, the moving unit 400, etc. Also, the operation of the injection molding machine 10 may be, for example, switching of a screen displayed on the touch panel 770 serving as the display device 760.

[0100] Although the operation device 750 and the display device 760 of this embodiment have been described as being integrated as the touch panel 770, they may be provided independently. Also, a plurality of operation devices 750 may be provided. The operation device 750 and the display device 760 are disposed on the operation side (negative Y-axis direction) of the mold clamping unit 100 (more specifically, the fixed platen 110).

[0101] (safety function) 1 and 2, the injection molding machine 10 has a case 940 that covers the mold clamping device 100, the ejector device 200, and the mold device 800. The case 940 serves as a protection that prevents a user of the injection molding machine 10 from coming into contact with the mold device 800, etc., during injection molding. The case 940 may be configured to cover the injection device 300 as well, or may be configured to cover the entire injection molding machine 10.

[0102] For example, the case 940 is formed in a rectangular shape (box shape) and is fixed to the upper surface of the frame 900 (mold clamping unit frame 910). A mouth portion (not shown) through which the cylinder 310 and nozzle 320 of the injection unit 300 can advance and retreat is provided on the side surface of the case 940 in the positive direction of the X axis.

[0103] The case 940 has one or more safety doors 941 that can be opened and closed by the user. FIGS. 1 and 2 show an example in which the safety door 941 is installed on the side of the case 940 on the Y-axis positive side (the side facing the viewer on the page). However, the installation position of the safety door 941 is not particularly limited, and it may be on the side on the Y-axis negative side, the side on the X-axis negative side, or the top surface on the Z-axis positive side. The safety door 941 may be a single-door, sliding door, or double-door door.

[0104] The injection molding machine 10 also has an open / close detector 942 that detects the open / close state of the safety door 941. The open / close detector 942 according to this embodiment is, for example, a type that employs a mechanical switch, and switches on and off the current that is output depending on the open / close state of the safety door 941. Note that this embodiment does not limit the type of the open / close detector 942, and for example, an optical sensor or the like may be employed.

[0105] The open / close detector 942 is communicatively connected to a PLC (Programmable Logic Controller) 710 provided in the internal space 922 vertically below the injection device frame 920 and to the control device 700, and transmits a signal indicating the open / close state of the safety door 941.

[0106] The PLC 710 is a computer that performs processing according to a procedure defined in a pre-stored program, and represents an example of a digital circuit for ensuring the safety of the injection molding machine 10.

[0107] In this embodiment, a safety PLC used to build a safety control system that complies with international safety standards (ISO13849 or IEC61508) is used as the PLC 710. For example, an IC chip certified under a safety standard is used as the calculation unit 720 of the PLC 710. In the PLC 710 according to this embodiment, a storage area for handling safety information is separated from a storage area 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 the safety information. Note that this embodiment describes an example in which a safety PLC is used as the PLC 710, but the present invention is not limited to the use of a safety PLC. A general-purpose PLC or a control device that employs another processor (such as a CPU, GPU, ASIC, or FPGA) may also be used.

[0108] Furthermore, in the PLC 710, an input unit 731 and an output unit 732 (described later) are multiplexed and made redundant. Furthermore, the PLC 710 performs self-diagnosis of the configuration included in the PLC 710 using a self-check function, thereby preventing a situation in which processing by the injection molding machine 10 continues if an abnormality occurs in the PLC 710.

[0109] 3 is a diagram showing an example of the electrical configuration of the PLC 710 according to this embodiment. As shown in FIG. 3, the PLC 710 includes an input unit 731, an output unit 732, a calculation unit 720, and a memory 730.

[0110] The calculation unit 720 is provided to control the operation of the PLC 710, and performs safety control of the injection molding machine 10 according to a pre-created program. For example, the calculation unit 720 performs control to stop a moving part when a predetermined event occurs.

[0111] The memory 730 is a storage area for storing data (data signals) used by the calculation unit 720.

[0112] The input unit 731 is connected to at least one input device selected from various sensors, switches, and buttons provided in the injection molding machine 10, and receives signals output from the input devices.

[0113] For example, the input unit 731 receives a signal indicating the detection result from an open / close detector 942 that detects the open / close state of a safety door 941. The input unit 731 also receives a signal indicating whether an emergency stop button 751 has been pressed. The input unit 731 also receives signals indicating the detection results from other safety sensors 752 provided in the injection molding machine 10.

[0114] The output unit 732 is connected to a mechanism for controlling a moving part provided in the injection molding machine 10, and outputs a signal to the mechanism. The signal output from the output unit 732 is, for example, a 24V voltage signal.

[0115] For example, the output unit 732 can output a 24V voltage signal to a motor driver 221A for driving the ejector motor 221. The output unit 732 according to this embodiment switches whether or not to output a 24V voltage signal in accordance with a program executed by the calculation unit 720.

[0116] The output unit 732 is also capable of outputting a 24V voltage signal to the motor brake 222 for stopping the ejector motor 221. The output unit 732 according to this embodiment switches whether or not to output the 24V voltage signal in accordance with the program executed by the calculation unit 720.

[0117] 3 indicates a mechanism for controlling the ejector motor 221, but the control target of the PLC 710 is not limited to the ejector motor 221. Any mechanism for driving a moving part provided in the injection molding machine 10 may be used, and for example, the control targets of the PLC 710 are the injection motor 350, the mold thickness adjustment motor 183, and the mold clamping motor 160. Furthermore, the control target of the PLC 710 is an injection molding machine moving motor (not shown) that moves the injection molding machine 10 from the frame.

[0118] For example, the output unit 732 can output a 24V voltage signal to a motor driver for driving the injection motor 350 and to a motor brake 352 for stopping the injection motor 350 .

[0119] Furthermore, the output unit 732 is capable of outputting a 24V voltage signal to a motor driver for driving the mold thickness adjustment motor 183 and to a motor brake 186 for stopping the mold thickness adjustment motor 183 .

[0120] Furthermore, the output unit 732 is capable of outputting a 24V voltage signal to a motor driver for driving the mold clamping motor 160 and a motor brake 162 for stopping the mold clamping motor 160 .

[0121] Below, we will explain the procedure by which the output unit 732 controls the ejector motor 221, but we will not explain it here as it performs similar control on the other injection motors 350, mold thickness adjustment motor 183, mold clamping motor 160, and injection molding machine movement motors (not shown).

[0122] For example, when a signal indicating that the safety door 941 has been opened (an example of the occurrence of a predetermined event) is received via the input unit 731 from the open / close detector 942 (an example of a detection unit) while the injection molding machine 10 is operating, the calculation unit 720 controls the output of a (24V voltage) signal (an example of a first signal) to the motor driver 221A to perform a power cut-off 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 start braking the ejector motor 221. The calculation unit 720 according to this embodiment controls the output of a signal (an example of a first signal) to cut off the power and then the output of a signal (an example of a second signal) to start braking the ejector motor 221, in that order. The control of the output of the signal to cut off the power is, for example, by stopping the 24V voltage signal, and the control of the output of the signal to start braking is, for example, by stopping the 24V voltage signal. In this embodiment, an example of stopping a voltage signal is shown as a way to control the output of a signal, but this may be determined according to the implementation, and may also be, for example, the output of a stop signal to cut off power or the output of a control signal to activate a motor brake.

[0123] Conventionally, when stopping a moving part (such as an ejector rod or a movable mold) in an injection molding machine, the power cutoff to the actuator that operates the moving part and the braking control using a brake to stop the actuator have tended to be performed by different control devices. When using different control devices, the timing order can be roughly maintained by incorporating an analog delay circuit such as a relay board, but the delay time varies depending on the part, so there is a possibility that the delay time will be excessively long.

[0124] Thus, when a moving part is stopped by executing a safety function, there is a tendency for the timing of braking control that is performed after power is cut off to vary. If the time from power cut off to the start of braking is set long, stopping of the moving part is delayed, which can cause loads to be placed on parts of the injection molding machine, particularly parts of the mold assembly, or on the molded product.

[0125] Furthermore, if the time from when the power is cut off until the brake starts to apply is set short, variations in timing may cause the power cut off to the actuator that operates the moving part and the start of braking by the brake to stop the actuator to occur in reverse. In this case, the power is cut off after braking control, and as a result, braking control by the brake is performed while the actuator is operating, resulting in wear due to brake drag.

[0126] Therefore, in this embodiment, the PLC 710 performs power cutoff and braking control. In other words, by using one PLC 710, when an event occurs that requires the moving part to be stopped (an example of a predetermined event), control can be performed so that the order of power cutoff and braking control is observed. The PLC 710 controls signals so that the order of power cutoff and braking is observed, thereby improving safety.

[0127] FIG. 4 is a functional configuration diagram showing the main configuration of the control device 700 and PLC 710 according to this embodiment. In FIG. 4, the components of the control device 700 and PLC 710 of the injection molding machine 10 are shown as functional blocks. The functional blocks shown in FIG. 3 are conceptual and do not necessarily have to be physically configured as shown. All or part of the functional blocks can be functionally or physically distributed or integrated in any unit. All or any part of the processing functions performed by the functional blocks in the control device 700 are realized by a program executed by the CPU 701. Alternatively, each functional block may be realized as hardware using wired logic.

[0128] As shown in FIG. 4, the CPU 701 of the control device 700 includes, for example, an input processing unit 711 and a speed control unit 712.

[0129] The input processing unit 711 receives and processes a signal indicating the detection result of a sensor provided in the injection molding machine 10. For example, the input processing unit 711 receives and processes a signal indicating the open / closed state of the safety door 941 from the open / close detector 942.

[0130] The speed control unit 712 controls the speed of the actuator by the motor driver based on the signal input and processed by the input processing unit 711. For example, when the speed control unit 712 recognizes that the safety door 941 is open based on the signal input and 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.

[0131] In the PLC 710, all or any part of the processing functions performed by each functional block are realized by a program executed by the calculation unit 720. Alternatively, each functional block may be realized as hardware using wired logic.

[0132] As shown in FIG. 4, the calculation unit 720 of the 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.

[0133] The input processing unit 721 receives and processes a signal indicating the detection result of a sensor provided in the injection molding machine 10. For example, the input processing unit 711 receives and processes a signal indicating the open / closed state of the safety door 941 from the open / close detector 942.

[0134] When the occurrence of a predetermined event is detected based on the signal input and processed by the input processing unit 721, the measurement unit 722 measures the elapsed time from the occurrence of the event. For example, when the measurement unit 722 detects that the safety door 941 is opened, it measures the elapsed time from the opening of the safety door 941. Note that in this embodiment, the occurrence of the predetermined event is not limited to when the safety door 941 is opened, and may also be when, for example, the emergency stop button 751 is detected to be pressed, or when another safety sensor 752 detects an abnormal state.

[0135] The driver control unit 723 uses the detection of the occurrence of a predetermined event as a trigger to perform control to stop the output of the 24V voltage signal in order to cut off power supply to the actuators provided in the injection molding machine 10 after a standby time (an example of a second time) has elapsed based on the measurement results of the measurement unit 722. The case where the standby time (an example of a second time) has elapsed since the detection of the occurrence of the predetermined event is, for example, the case where 100 ms has elapsed since the safety door 941 was opened.

[0136] The brake control unit 724 is triggered by the detection of the occurrence of a predetermined event, and after a time (an example of a first time) equal to the sum of a waiting time and a delay time measured by the measurement unit 722 has elapsed, performs control to stop the output of a 24V voltage signal to the motor brake in order to perform braking control on the actuator provided in the injection molding machine 10. The delay time is the time elapsed from when the output of the 24V voltage signal was stopped to cut off power, and is set to 50 ms, for example. In other words, when a time equal to the sum of the waiting time and the delay time, 150 ms, has elapsed since the occurrence of the predetermined event was detected, the brake control unit 724 performs control to stop the output of the 24V voltage signal to the motor brake.

[0137] In this embodiment, an example has been described in which the detection of the occurrence of a predetermined event is used as a trigger to start braking control after the total time of the waiting time and the delay time has elapsed. However, this embodiment does not limit the trigger for starting measurement of the detection of the occurrence of the predetermined event to the timing when the occurrence of the predetermined event is detected. For example, a method may be used in which the power interruption is used as a trigger to start braking control after the delay time has elapsed.

[0138] FIG. 5 is a timing chart of the power cutoff and braking control by the motor brake 222 that is performed when the safety door 941 is opened in the injection molding machine 10 according to this embodiment.

[0139] 5, it is assumed that the safety door 941 is opened at time t1. The open / close detector 942 outputs a signal indicating that the safety door 941 is open to the control device 700 and the PLC 710. At the timing when the input processing unit 711 of the control device 700 inputs and processes the signal, the speed control unit 712 starts controlling the motor driver (e.g., motor driver 221A) to reduce the speed of the actuator (e.g., ejector motor 221).

[0140] Meanwhile, in the PLC 710, at the timing when the input processing unit 711 inputs and processes the signal, the measurement unit 722 measures the time that has passed since the safety door 941 opened. Then, at time t2, when a waiting time (e.g., 100 ms) has elapsed since time t1, the driver control unit 723 stops outputting the 24V voltage signal and performs a power cutoff to cut off the power supply to an actuator (e.g., ejector motor 221) provided in the injection molding machine 10. Therefore, as shown by line 1502, the power cutoff is turned on at time t2.

[0141] Furthermore, in the PLC 710, at time t3 when a delay time (for example, 50 ms) has elapsed since time t2, the brake control unit 724 stops outputting the 24V voltage signal and performs braking control using a brake (for example, the motor brake 222 provided on the ejector motor 221) provided in the injection molding machine 10. Therefore, as shown by line 1503, the motor brake 222 switches from release to braking start at time t3.

[0142] The PLC 710 according to this embodiment stores a waiting time and a delay time in advance in a storage unit (not shown). When a program is executed in the calculation unit 720, the waiting time and the delay time stored in the storage unit are referenced to perform the above-described control. The waiting time and the delay time may be set by the user.

[0143] In this embodiment, power cut-off and braking by the motor brake 222 are performed in that order, thereby reducing wear on the motor brake 222. In this embodiment, the delay time between power cut-off and the start of braking control by the motor brake 222 is set so as to make the time between power cut-off and the start of braking control as short as possible while performing the operations in order. In other words, this embodiment does not limit the delay time to 50 ms, as long as the time between power cut-off and braking control is as short as possible while performing the power cut-off and braking control in order.

[0144] Furthermore, in this embodiment, when the safety door 941 is opened, the control device 700 controls to reduce the speed of the ejector motor 221, and after a waiting time has elapsed since the safety door 941 was detected, the PLC 710 cuts off the power. By cutting off the power after the speed of the ejector motor 221 has been reduced, the movement speed of the ejector device 200 after the power is cut off can be reduced, and the amount of wear on the motor brake 222 due to the subsequent braking control can be reduced.

[0145] Furthermore, in this embodiment, even if the control device 700 does not control a speed reduction, the PLC 710 performs the power cutoff and braking control using the brakes in the above-described procedure. In other words, even if the control device 700 does not operate as intended, the PLC 710 stops the ejector motor 221 by cutting off the power and performing braking control using the brakes. In this way, the PLC 710 according to this embodiment cuts off the power and performs braking control regardless of whether the control device 700 has reduced the speed of the ejector motor 221, thereby improving the reliability of stopping the ejector motor 221. Therefore, improved safety can be achieved.

[0146] In this embodiment, an example has been described in which the control of reducing the speed of the ejector motor 221 by the control device 700 is combined with the braking control by cutting off power and using the brake by the PLC 710. However, this embodiment is not limited to a method in which the control of reducing the speed of the ejector motor 221 by the control device 700 is combined with the braking control by cutting off power and using the brake by the PLC 710. For example, the control of reducing the speed of the ejector motor 221 by the control device 700 may not be performed, and only the braking control by cutting off power and using the brake by the PLC 710 may be performed.

[0147] In this embodiment, an example has been described in which the configuration for cutting off power (motor driver and actuator) and the configuration for performing braking control (motor brake) are provided separately. However, this embodiment is not limited to an example in which the configuration for cutting off power and the configuration for performing braking control are provided separately. The configuration for cutting off power and the configuration for performing braking control may also be integrated.

[0148] (Second embodiment) In the first embodiment, a case where the PLC 710 directly controls the motor brake 222 and the motor driver (for example, the motor driver 221A) has been described. However, the first embodiment is not limited to a method of directly controlling the motor brake 222 and the motor driver (for example, the motor driver 221A). Therefore, in the second embodiment, a case where control is performed via a relay will be described.

[0149] Fig. 6 is a diagram showing an example of the electrical configuration of a PLC 710 according to this embodiment. As shown in Fig. 6, the PLC 710 includes an input unit 731, an output unit 732, a calculation unit 720, and a memory 730, similar to the first embodiment. In this embodiment, the same components as those in the first embodiment are assigned the same reference numerals, and their description will be omitted.

[0150] In this embodiment, a relay 1601 is provided between the PLC 710 and the ejector motor 221 and motor driver 221A. Furthermore, a relay 1602 is provided between the PLC 710 and the motor brake 222.

[0151] The motor driver 221A is connected to a 24V power supply 1603 via a relay 1601. When the PLC 710 outputs a 24V voltage signal, electricity flows through a coil 1601A in the relay 1601, generating a magnetic field. The magnetic field causes an iron piece (not shown) to come into contact with a contact point, and power is supplied from the 24V power supply 1603 to the motor driver 221A.

[0152] Furthermore, the motor brake 222 is connected to a 24V power supply 1604 via a relay 1602. When the PLC 710 outputs a 24V voltage signal, electricity flows through a coil 1602A in the relay 1602, generating a magnetic field. The magnetic field causes an iron piece (not shown) to come into contact with a contact, and power is supplied to the motor brake 222 from the 24V power supply 1604.

[0153] That is, even when the relays 1601 and 1602 are provided as in this embodiment, the PLC 710 can control the motor driver 221A and the motor brake 222 by performing the same control as in the first embodiment.

[0154] The PLC 710 according to this embodiment is connected to the motor driver 221A and the motor brake 222 via relays 1601 and 1602. Therefore, when an overcurrent occurs in the motor driver 221A, the motor brake 222, or the like, the relays 1601 and 1602 can prevent the overcurrent from affecting the PLC 710. This improves the safety of the PLC 710.

[0155] (Variation) In the above-described embodiment, the injection molding machine 10 is a horizontal machine. However, the above-described embodiment is not limited to the case where the injection molding machine 10 is a horizontal machine, and a vertical machine may also be used. Therefore, the case where a vertical machine is used will be described.

[0156] Safety standards (ISO20430 (JIS B6711)) stipulate that injection molding machines must prevent movement due to gravity. In other words, if a vertical machine is used as injection molding machine 10 as a modified example, when operating a movable part that can move in the direction of gravity (for example, mold opening / closing, mold thickness movement, injection unit movement), it is necessary to prevent movement due to gravity using a braking device (for example, a motor brake).

[0157] Furthermore, if the power cutoff and braking control to stop the actuator are performed by separate control devices as in the past, a large amount of energy must be stopped if there is a time difference between the power cutoff and the braking control, which requires that the power cutoff and braking control be performed at appropriate timing.

[0158] Therefore, in this modification, as in the above-described embodiment, the PLC 710 sequentially performs, at predetermined timings, power cutoff for the actuator that operates the moving part of the vertical injection molding machine, and braking control using the motor brake. In this modification, more accurate timing control can be performed than when an analog delay circuit is used, thereby improving safety.

[0159] <effect> By performing the above-described control, the PLC 710 according to the embodiment and the modified example can maintain the order of power cutoff for the actuator that operates the moving part and braking control that stops the actuator. Therefore, power cutoff after braking control can be prevented, thereby preventing brake wear.

[0160] Furthermore, since the PLC 710 can control the timing of power cutoff and braking control, it is possible to prevent loads from being placed on the components of the injection molding machine 10 due to variations in the timing of braking control.

[0161] In the above-described embodiment and modified examples, the calculation unit 720 configured as a digital circuit performs power cutoff and braking control according to a pre-created program, thereby enabling more accurate timing control than when an analog delay circuit is used.

[0162] Furthermore, the PLC 710 according to the above-described embodiment and modified example uses a safety PLC, which allows the input unit 731, output unit 732, etc. to be multiplexed and redundant, and also allows self-diagnosis using a self-check function, thereby improving safety. Specifically, since the input unit 731, output unit 732, etc. are multiplexed and redundant, the reliability of stopping control of the moving parts of the injection molding machine 10 is improved according to a pre-created program, thereby improving safety.

[0163] The PLC (an example of a control device) provided in an injection molding machine and an embodiment of the injection molding machine according to the present invention have been described above, but the present invention is not limited to the above-described embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These changes also naturally fall within the technical scope of the present invention. [Explanation of symbols]

[0164] 10 injection molding machine 160 Mold clamping motor 162 Motor brake 183 Mold thickness adjustment motor 186 Motor Brake 221 Ejector 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 section 710 PLC 720 Arithmetic unit 721 Input Processing Unit 722 Measuring part 723 Driver control unit 724 Brake control unit 730 memory 731 Input section 732 Output section 751 Emergency Stop Button 752 Other Safety Sensors 940 cases 941 Safety Door 942 Open / Close Detector

Claims

1. a digital circuit for sequentially controlling, when a signal indicating that a predetermined event has been detected is received from a detection unit provided in an injection molding machine, the injection molding machine including a motor that supplies power for moving a movable part and a brake for the motor, to output a first signal for cutting off power supply to the motor and a second signal for starting braking by the brake; A control device for an injection molding machine comprising:

2. when detecting the occurrence of a predetermined event, the digital circuit controls the output of the first signal, and then controls the output of the second signal after a first time has elapsed. The control device for an injection molding machine according to claim 1.

3. the digital circuit controls the output of the first signal after a second time period has elapsed when the digital circuit detects the occurrence of a predetermined event; The control device for an injection molding machine according to claim 1.

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

5. The motor is an ejector motor that drives an ejector provided in the injection molding machine, a mold clamping motor that clamps a mold device provided in the injection molding machine, an injection motor that moves a screw in a cylinder provided in the injection molding machine back and forth, a mold thickness adjustment motor that adjusts the gap between a fixed platen and a toggle support provided in the injection molding machine, or an injection molding machine movement motor that moves the injection molding machine from a frame.

5. The injection molding machine according to claim 4.

6. a relay is provided between the control device and the brake, and a relay is provided between the control device and the motor; 5. The injection molding machine according to claim 4.

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