Control device of injection molding machine and control method of injection molding machine

Abstract

Provided is a technology for setting a timing of increasing clamp force. A control device of an injection molding machine has a clamp control section and a monitoring section. The clamp control section changes a set value of clamp force from a first set value to a second set value that is greater than the first set value at a prescribed timing of increasing that is in the middle of a filling process of filling a molding material into an interior of a mold device that is clamped. The monitoring section monitors a change in an actual value of the clamp force that accompanies the change in the set value of the clamp force.

Description

Technical Field

[0001] This application claims priority based on Japanese Patent Application No. 2021-199207, filed on December 8, 2021. The entire contents of that Japanese application are incorporated herein by reference.

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

[0003] Patent Document 1 discloses a composite resin molding apparatus comprising a pressure section and an injection section. The pressure section includes a base, multiple drive sections disposed on the base, and a sliding member driven by the drive sections. A mold section is mounted on the pressure section. The mold section includes an upper mold section mounted on the sliding member and a lower mold section placed on the base. While the sliding member is positioned in the pressure section with a small gap between the upper and lower mold sections, the injection section injects material into the mold section. When material is injected into the mold section, if there is a portion where the load applied to the sliding member from below due to the material exceeds the load applied to the sliding member by the drive sections, that portion retracts upwards.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2019-093576

[0005] The following technology is under development: During a predetermined pressurization timing midway through the filling process of filling molding material into the mold assembly in the mold clamping device, the setting value of the clamping force is changed from a first setting value to a second setting value greater than the first setting value. By setting the clamping force to low before the midway through the filling process, the generation of gas burning can be suppressed; by setting the clamping force to high after the midway through the filling process, the generation of burrs can be suppressed.

[0006] If the clamping force is increased too early, the gas will have difficulty escaping from the inside of the mold assembly to the outside. Inside the mold assembly, the gas will be compressed and generate heat, leading to gas burning. Furthermore, if the clamping force is increased too late, the molding material will leak between the fixed and moving molds, resulting in burrs. Previously, skilled operators set the pressure timing based on their experience, making it difficult for non-skilled personnel to do so. Summary of the Invention

[0007] One aspect of the present invention provides a technique for setting the timing of the pressurization of the clamping force.

[0008] The control device for an injection molding machine according to one aspect of the present invention includes a mold clamping control unit and a monitoring unit. The mold clamping control unit changes a set value of the clamping force from a first set value to a second set value greater than the first set value at a predetermined pressure increase time during the filling process of filling molding material into the mold assembly within the mold. The monitoring unit monitors the change in the actual value of the clamping force accompanying the change in the set value of the clamping force.

[0009] Invention Effects

[0010] According to one aspect of the present invention, by monitoring the change in the actual value of the clamping force accompanying a change in the set value of the clamping force, the filling status of the molding material can be inferred. As a result, it is possible to support the setting of the clamping force pressurization timing. Attached Figure Description

[0011] Figure 1 This is a diagram showing the state of the injection molding machine at the end of mold opening according to one embodiment.

[0012] Figure 2 This is a diagram showing the state of the injection molding machine during mold closing according to one embodiment.

[0013] Figure 3 This is a diagram illustrating an example of how function blocks represent the components of a control device.

[0014] Figure 4 This is a diagram illustrating an example of a process in the molding cycle.

[0015] Figure 5 This is a cross-sectional view showing an example of molding material flowing into the mold assembly.

[0016] Figure 6 This is the first example of a graph showing the change in the actual value of the clamping force.

[0017] Figure 7 This is the second example of a graph showing the change in the actual value of the clamping force.

[0018] In the diagram: 10-Injection molding machine, 100-Mold closing device, 300-Injection device, 700-Control device, 711-Mold closing control unit, 715-Monitoring unit, 800-Mold device. Detailed Implementation

[0019] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, in the drawings, the same or corresponding structures are sometimes labeled with the same symbols, and descriptions are omitted.

[0020] (Injection molding machine)

[0021] Figure 1This is a diagram showing the state of the injection molding machine at the end of mold opening according to one embodiment. Figure 2 This diagram illustrates the mold-closing state of the injection molding machine according to one embodiment. 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 represents the mold opening and closing direction, and the Y-axis represents 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.

[0022] 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 for supporting the mold clamping device 100; and an injection device frame 920 for supporting the injection device 300. The mold clamping device frame 910 and the injection device frame 920 are respectively mounted on the base plate 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.

[0023] (Mold closing device)

[0024] 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.

[0025] The mold closing device 100 performs mold closing, pressurization, mold closing, depressurization, and mold opening of the mold device 800. The mold device 800 includes a fixed mold 810 and a moving mold 820.

[0026] 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 moving 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.

[0027] 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.

[0028] 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 moving mold 820 is mounted on the surface of the movable pressure plate 120 opposite to the fixed pressure plate 110.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] Connecting rods 140 connect 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 installed 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.

[0033] 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.

[0034] 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.

[0035] 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 3rd link 154 is connected to the 1st link 152 and the 2nd link 153.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] In the pressurization process, the mold closing 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 closing force.

[0042] 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 cured to obtain a molded product.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] In addition, the moving speed and position of the movable pressure plate 120 can be set instead of the moving speed and position of the crosshead 151. Furthermore, the clamping force can be set instead of the position of the crosshead (e.g., the mold closing position) and the position of the movable pressure plate.

[0049] 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°.

[0050] 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 the linkage angle θ of the toggle mechanism 150 becomes the specified angle at the moment when the moving mold 820 contacts the fixed mold 810.

[0051] 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 performed, 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 non-retractable movement; and a mold thickness adjustment motor 183 that rotates the lead screw nut 182 screwed to the lead screw shaft 181.

[0052] 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. In addition, by changing the transmission path of the rotational driving force transmission unit 185, multiple lead screw nuts 182 can also be rotated individually.

[0053] The rotary drive force transmission unit 185 is composed of, for example, 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, instead of gears, the rotary drive force transmission unit 185 may also be composed of belts and pulleys.

[0054] 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.

[0055] 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 to monitor and control 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.

[0056] 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.

[0057] 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.

[0058] Furthermore, the mold clamping device 100 of this embodiment includes a mold clamping motor 160 as a drive unit, but a hydraulic cylinder may be used instead of the mold clamping motor 160. Also, the mold clamping device 100 may include a linear motor for mold opening and closing, or it may include an electromagnet for mold clamping.

[0059] (Ejection device)

[0060] In the description of the ejector device 200, similar 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.

[0061] Ejection device 200 is mounted on movable pressure plate 120 and moves forward and backward together with movable pressure plate 120. Ejection device 200 includes: 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.

[0062] 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.

[0063] The drive mechanism 220 includes, for example, an ejector motor and a motion conversion mechanism that converts the rotational motion of the ejector motor 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.

[0064] The ejection 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 ejection motor 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.

[0065] For example, an ejector motor encoder is used to detect the position and speed of the ejector rod 210. The ejector motor encoder detects the rotation of the ejector motor 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 speed detector for detecting the speed of the ejector rod 210 are not limited to the ejector motor encoder, and conventional detectors can be used.

[0066] (Injection device)

[0067] 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.

[0068] 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. The injection unit 300 includes, for example, a cylinder 310 for heating the molding material, a nozzle 320 disposed 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.

[0069] 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 first heater 313, such as a belt heater, and a first temperature detector 314 are provided on the outer periphery of the cylinder body 310, further forward than the cooler 312.

[0070] The cylinder block 310 is divided into multiple regions along its axial direction (e.g., the X-axis direction). A first heater 313 and a first temperature detector 314 are respectively provided in each of the multiple regions. A set temperature is set for each of the multiple regions, and the control device 700 controls the first heater 313 so that the temperature detected by the first temperature detector 314 becomes the set temperature.

[0071] The nozzle 320 is located at the front end of the cylinder 310 and presses against the mold assembly 800. A second heater 323 and a second temperature detector 324 are provided on the outer periphery of the nozzle 320. The control device 700 controls the second heater 323 so that the detected temperature of the nozzle 320 becomes the set temperature.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[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 to control and monitor the pressure on the screw 330 from the molding material, the back pressure on the screw 330, and the pressure acting on the molding material from the screw 330.

[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. The mold pressure sensor is located inside the mold assembly 800.

[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 screw 330 from retracting too rapidly, 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 predetermined 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. Instead of stopping the screw 330 immediately before the V / P switch, the screw 330 can be moved forward or backward at a slight speed. 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 any insufficient molding material in the mold assembly 800 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 for each of the multiple holding pressure processes can be set separately, 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 with a rotational direction and rotational torque corresponding to the control signal 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 serves as a first chamber, and a rear chamber 436, which serves as 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 a memory, an input interface 703, and an output interface 704. 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 manufactures molded products by performing metering, mold closing, pressurization, mold closing, filling, pressure holding, cooling, depressurization, 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 very beginning of the molding cycle. The filling process can also begin during the mold closing process. 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 backfeeding 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, preventing 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, 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 receives 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. Furthermore, operation sections such as buttons and input fields for receiving user input can be displayed on the screen 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 simultaneously check the information displayed on the screen and operate the operation sections on the screen to set the injection molding machine 10 (including inputting setting values). Furthermore, by operating the operation sections 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] (Detailed description of the control device)

[0115] Next, refer to Figure 3An example of the constituent elements of the control device 700 will be described. Furthermore, Figure 3 The functional blocks illustrated are conceptual and do not necessarily need to be physically configured as shown. All or part of each functional block can be functionally or physically distributed / integrated in any unit. All or any part of the processing functions performed by each functional block can be implemented by a program executed by the CPU or by hardware based on wiring logic.

[0116] like Figure 3 As shown, the control device 700 includes, for example, a mold closing control unit 711, an ejection control unit 712, an injection control unit 713, and a metering control unit 714. The mold closing control unit 711 controls the mold closing drive source of the mold closing device 100 and implements... Figure 4 The diagram illustrates the mold closing process, pressure boosting process, mold clamping process, pressure release process, and mold opening process. The mold clamping drive source is, for example, a mold clamping motor 160, but could also be a hydraulic cylinder, etc. The ejection control unit 712 controls the ejection device 200 and performs the ejection process. The injection control unit 713 controls the injection drive source of the injection device 300 and performs the injection process. The injection drive source is, for example, an injection motor 350, but could also be a hydraulic cylinder, etc. The injection process includes a filling process and a holding pressure process. The injection process is performed during the mold clamping process. The metering control unit 714 controls the metering drive source of the injection device 300 and performs the metering process. The metering drive source is, for example, a metering motor 340, but could also be a hydraulic pump, etc. The metering process is performed during the cooling process.

[0117] The filling process is a process of controlling the injection drive source so that the actual value of the moving speed of the injection component located inside the cylinder 310 is equal to a set value. The filling process is a process of filling the mold assembly 800 with liquid molding material accumulated in front of the injection component by moving the injection component forward. The injection component is, for example, a screw 330 (see reference). Figure 1 and Figure 2 (It can also be a plunger.)

[0118] The movement speed of the injection unit is detected using a speed detector. The speed detector is, for example, an injection motor encoder 351. During the filling process, as the injection unit advances, the pressure (hereinafter also referred to as "fill pressure") acting on the molding material from the injection unit increases. The filling process, preceding the holding pressure process, may include a process that temporarily stops the injection unit or a process that retracts the injection unit.

[0119] The holding pressure process is a process of controlling the injection drive source to ensure that the actual filling pressure value is the set value. The holding pressure process replenishes the amount of molding material in the mold assembly 800 that is insufficient due to cooling shrinkage by pressing the injection component forward. The filling pressure is detected using a pressure detector such as a load detector 360. A nozzle pressure sensor or a mold pressure sensor can be used as the pressure detector.

[0120] Next, refer to Figure 5 An example of molding material M flowing into the mold assembly 800 will be described. Molding material M is, for example, resin. Molding material M flows into the cavity space 801 inside the mold assembly 800. Cavity space 801 is formed at the parting surface 830 between the fixed mold 810 and the moving mold 820. Parting surface 830 is commonly referred to as parting line.

[0121] If the filling pressure P1 is greater than the mold closing pressure P2, the fixed mold 810 and the moving mold 820 open, causing the molding material M to leak. This results in a defect known as burrs. Burrs are the phenomenon where the molding material M leaks between the fixed mold 810 and the moving mold 820 and solidifies. To suppress burr formation, the mold closing force F tightens the fixed mold 810 and the moving mold 820. Furthermore, the mold closing pressure P2 is the value obtained by dividing the mold closing force F by the area S of the parting surface 830 (P2 = F / S).

[0122] However, if the clamping pressure P2 and clamping force F are too high, the gas in the cavity space 801 will have difficulty escaping to the outside of the mold device 800 via the parting surface 830 when the molding material M flows into the cavity space 801. This will result in a defect known as "gas burning." Gas burning is the phenomenon where the molding material M carbonizes due to the heat generated by the compression of the gas in the cavity space 801. When gas burning occurs, the gas in the cavity space 801 has difficulty escaping to the outside of the mold device 800, and the gas tends to remain in the cavity space 801, which may also lead to a defect known as "insufficient filling." Insufficient filling is the phenomenon where the molding material M is cooled and solidified before filling the entire cavity space 801.

[0123] After the molding material M is injected by the injection device 300, it flows through the sprue (not shown) of the fixed mold 810 and into the cavity space 801 formed between the fixed mold 810 and the moving mold 820. Before the flow tip of the molding material M reaches the parting surface 830 of the fixed mold 810 and the moving mold 820, even if the clamping force F is low, the fixed mold 810 and the moving mold 820 will not open, thus preventing burrs from being generated.

[0124] To suppress the generation of burrs and burn-out, the mold clamping control unit 711 changes the set value of the clamping force F from a first set value F1 (F1 > 0) to a second set value F2 (F2 > F1) that is greater than the first set value F1 by using a pre-set pressure increase timing during the filling process. By setting the clamping force F to low before the middle of the filling process, the generation of burn-out can be suppressed; by setting the clamping force F to high after the middle of the filling process, the generation of burrs can be suppressed. By setting the clamping force F to low before the middle of the filling process, not only the generation of burn-out can be suppressed, but also the generation of incomplete filling can be suppressed.

[0125] The timing of the clamping force F is set, for example, using the position of the injection unit. After the filling process begins, the injection unit is advanced. The position of the injection unit is detected using a position detector. The position detector is, for example, an injection motor encoder 351. If the position of the injection unit reaches a set position (hereinafter also referred to as the clamping force switching position), the set value of the clamping force F changes from the first set value F1 to the second set value F2.

[0126] The further forward the clamping force switching position is moved, the later the pressure boosting timing. The pressure boosting timing is set midway through the filling process; therefore, the clamping force switching position is set further forward than the filling start position and further backward than the V / P switching position. Additionally, the pressure boosting timing can be set using elapsed time since the start of the filling process. If the elapsed time reaches the set time, the set value of the clamping force F changes from the first set value F1 to the second set value F2.

[0127] However, if the clamping force F is increased too early, the gas will have difficulty escaping from the inside of the mold assembly 800 to the outside. Inside the mold assembly 800, the gas will be compressed and heated, leading to gas burning. Furthermore, if the clamping force F is increased too late, the molding material M will leak between the fixed mold 810 and the moving mold 820, resulting in burrs. Previously, skilled operators set the pressure timing based on their experience; setting the pressure timing is more difficult for non-skilled personnel.

[0128] like Figure 3 As shown, the control device 700 includes a monitoring unit 715. The monitoring unit 715 monitors the change in the actual value of the clamping force F as the set value of the clamping force F changes. If the set value of the clamping force F changes, the actual value of the clamping force F changes; therefore, the monitoring unit 715 monitors this subsequent change. The monitoring unit 715 uses a clamping force detector such as a connecting rod strain detector 141 to obtain the actual value of the clamping force F. Details will be described later, but based on the change in the actual value of the clamping force F, the filling status of the molding material M can be inferred. Therefore, by simply monitoring the change in the actual value of the clamping force F, the setting of the pressurization timing can be supported.

[0129] The mold clamping control unit 711, for example, converts the set value of the clamping force F into the set value of the crosshead position, and controls the mold clamping motor 160 so that the actual value of the crosshead position becomes the set value. The first set value F1 and the second set value F2 of the clamping force F are converted into the first set value and the second set value of the crosshead position. The crosshead position is the relative position of the crosshead 151 with respect to the toggle seat 130. The further the crosshead 151 advances, the greater the clamping force F.

[0130] If the molding material M reaches the parting surface 830 between the fixed mold 810 and the moving mold 820, and the fixed mold 810 and the moving mold 820 open due to the filling pressure P1, then the gap L between the fixed pressure plate 110 and the toggle seat 130 increases. The increased gap L indicates that the connecting rod 140 extends, and that the actual value of the clamping force F increases. Therefore, based on the change in the actual value of the clamping force F, the filling status of the molding material M can be inferred.

[0131] like Figure 3 As shown, the control device 700 may include a judgment unit 716. The judgment unit 716 determines whether the pressurization timing is appropriate based on the change in the actual value of the clamping force F monitored by the monitoring unit 715. For example, the judgment unit 716 uses the overshoot ΔF (reference) of the actual value relative to the second set value F2. Figure 6 To determine if the boost timing is appropriate, check if it is below the upper limit value ΔFmax. Figure 6 In the diagram, the solid line represents the change in the actual value of ΔF when it is below ΔFmax, and the dashed line represents the change in the actual value of ΔF when it exceeds ΔFmax.

[0132] In addition, Figure 6 In this process, after the set value of the clamping force F is changed from the first set value F1 to the second set value F2, the actual value of the clamping force F is stabilized with the second set value F2, but sometimes it is stabilized with the value F2′ (F2′=F2+E (E is a value other than zero)) which is the displacement from the second set value F2. In the latter case, F2′ is used instead of F2 as the reference value for the overshoot ΔF. The judgment unit 716 determines whether the pressure boosting timing is appropriate by whether the overshoot ΔF of the actual value relative to the specified reference value (e.g., F2 or F2′) is below the upper limit value ΔFmax. The error E is, for example, the error generated when converting the set value of the clamping force F into the set value of the crosshead position, or the error generated due to the dimensional change of the mold device 800 accompanied by temperature changes.

[0133] The upper limit value ΔFmax is set to prevent burrs. When the pressurization timing is too late, the mold closing pressure P2 when the molding material M reaches the parting surface 830 of the fixed mold 810 and the moving mold 820 is less than the filling pressure P1, which will cause the fixed mold 810 and the moving mold 820 to open. As a result, the overshoot ΔF (ΔF>0) will exceed the upper limit value ΔFmax, which will cause burrs to be generated.

[0134] Furthermore, even if the fixed mold 810 and the moving mold 820 are opened, as long as the opening amount is small, the molding material M will not leak due to its stickiness, thus preventing burrs from forming. The upper limit value ΔFmax is set, for example, for each mold assembly 800. The upper limit value ΔFmax can be set and changed. For example, an operator can manually set the upper limit value ΔFmax by entering a value in the input field on the screen. Alternatively, the control device 700 can use an image of the molded product to detect the presence of burrs and automatically set the upper limit value ΔFmax based on the detection results.

[0135] If the overshoot ΔF exceeds the upper limit ΔFmax, the opening amount of the fixed mold 810 and the moving mold 820 will be large, resulting in burrs. Therefore, the judgment unit 716 determines that the boost timing is inappropriate. On the other hand, when the overshoot ΔF is below the upper limit ΔFmax, the opening amount of the fixed mold 810 and the moving mold 820 is small and no burrs are generated. Therefore, the judgment unit 716 determines that the boost timing is appropriate.

[0136] Furthermore, in this embodiment, the determination unit 716 determines whether the boost timing is appropriate, but the determination can also be made by an operator. That is, in this embodiment, the determination of whether the boost timing is appropriate is automatic, but it can also be made manually. When manually determining whether the boost timing is appropriate, for example, the display control unit 720 of the control device 700 (see reference...) Figure 3 The monitoring results of the monitoring unit 715 are displayed on the display device 760.

[0137] By observing the monitoring results displayed on the monitoring unit 715 of the display device 760, the operator can determine whether the timing of the pressure boost is appropriate. The content displayed on the display device 760 includes, for example, the waveform of the actual value of the clamping force F and the boundary line BL representing the upper limit value ΔFmax (see reference). Figure 6 Alternatively, the content displayed on the display device 760 may include the overshoot ΔF. The overshoot ΔF may be displayed as a numerical value, or it may simply indicate whether the upper limit value ΔFmax has been exceeded.

[0138] like Figure 3As shown, the control device 700 may include a setting change unit 717. The setting change unit 717 changes the setting of the boost timing based on changes in the actual value of the clamping force F monitored by the monitoring unit 715. For example, the setting change unit 717 changes the boost timing setting so that the overshoot ΔF becomes below the upper limit value ΔFmax. When the overshoot ΔF exceeds the upper limit value ΔFmax, the setting change unit 717 changes the boost timing setting to be advanced. The setting change amount can be a predetermined amount or an amount corresponding to the overshoot ΔF. In the latter case, the larger the overshoot ΔF, the larger the setting change amount. The setting change unit 717 can repeatedly change the boost timing setting to be advanced until the overshoot ΔF becomes below the upper limit value ΔFmax.

[0139] The setting change unit 717 repeatedly changes the pressure boosting timing setting, and measures the overshoot ΔF for each pressure boosting timing. If the overshoot ΔF falls below the upper limit value ΔFmax, the latest pressure boosting timing is set as the next subsequent pressure boosting timing. This suppresses the generation of spikes and postpones the pressure boosting timing as much as possible, thereby suppressing gas burning. It can automatically set pressure boosting timings that were previously only set by skilled operators.

[0140] When repeatedly changing the boost timing setting, the setting change unit 717 can repeatedly change the boost timing setting to be advanced, or repeatedly change the boost timing setting to be postponed, or it can perform both processes of changing the boost timing setting to be advanced and changing the boost timing setting to be postponed. In short, as long as the overshoot ΔF is below the upper limit value ΔFmax, the latest boost timing can be set as the boost timing after the next one.

[0141] Changing the pressure boosting timing setting to earlier includes, for example, changing the mold clamping force switching position setting to later. On the other hand, changing the pressure boosting timing setting to later includes, for example, changing the mold clamping force switching position setting to earlier. As described above, the pressure boosting timing can be set using the elapsed time from the start of the filling process instead of the mold clamping force switching position.

[0142] The setting modification unit 717, for example, changes the setting of the pressure boosting timing in the (n+1)th and subsequent molding cycles based on the overshoot ΔF in the nth (n is a natural number greater than or equal to 1) molding cycle. In the (n+1)th and subsequent molding cycles, it can suppress the generation of burrs and postpone the pressure boosting timing as much as possible, thereby also suppressing the generation of gas burning.

[0143] Furthermore, in this embodiment, the setting change unit 717 changes the boost timing setting, but the boost timing setting can also be changed by an operator. That is, in this embodiment, the boost timing setting is changed automatically, but the boost timing setting can also be changed manually.

[0144] For example, while observing the monitoring results displayed on the monitoring unit 715 of the display device 760, the operator changes the boost timing setting. This setting change is performed by the operator entering the boost timing in the input field of the screen. The operator can repeatedly change the boost timing setting and measure the overshoot ΔF for each boost timing. The operator enters the latest boost timing as the next boost timing in the input field of the screen when the overshoot ΔF is below the upper limit value ΔFmax.

[0145] Next, refer to Figure 7 right Figure 6 The following are modified examples. In the above embodiments, such as Figure 6 As shown by the dashed line, when the pressure increase timing is late, the actual value of the clamping force F exceeds the second set value F2 and then decreases towards the second set value F2. This is because the clamping pressure P2 (P2 = F2 / S) is greater than the filling pressure P1, and the fixed mold 810 and the moving mold 820 close after opening.

[0146] On the other hand, in this variant example, such as Figure 7 As shown by the solid line, after the actual value of the clamping force F exceeds the second set value F2, it remains constant after shifting from the second set value F2. This is because the clamping pressure P2 (P2 = F2 / S) is less than the filling pressure P1, and the fixed mold 810 and the moving mold 820 will not close after opening.

[0147] Furthermore, the technique of this modified example can also be applied when the actual value of the clamping force F exceeds the second set value F2 and then decreases towards the second set value F2. This is because, regardless of the magnitude of the second set value F2, the reference timing t0 described later represents the timing at which the molding material M reaches the parting surface 830.

[0148] Similarly, the technique described above can also be applied when the actual value of the clamping force F exceeds the second set value F2 and then remains constant after shifting from the second set value F2. This is because, regardless of the behavior after the second set value F2 reaches its maximum value, the overshoot ΔF can be used to determine whether the boost timing is appropriate and unchanged.

[0149] In this modified example, the judgment unit 716 determines whether the pressure boosting timing is appropriate based on whether the timing at which the actual value of the clamping force F reaches the second set value F2 falls within the allowable range Δt. The allowable range Δt has a lower limit and an upper limit. The allowable range Δt has a width, and its lower limit and upper limit are different; however, the allowable range Δt can be a point, and its lower limit and upper limit can be the same. The allowable range Δt can be set manually or automatically. Figure 3 The allowable range setting unit 718 shown is set. Hereinafter, the timing at which the actual value of the clamping force F reaches the second set value F2 will be referred to as the "reaching timing".

[0150] In addition, Figure 7 In this process, after the set value of the clamping force F is changed from the first set value F1 to the second set value F2, the actual value of the clamping force F stabilizes with the second set value F2, but sometimes it stabilizes with the value F2′ (F2′=F2+E (E is a value other than zero)) which is a displacement from the second set value F2. In the latter case, the timing of reaching F2′ can be used as the timing of the actual value of the clamping force F. The judgment unit 716 determines whether the pressure boosting timing is appropriate by whether the timing of the actual value of the clamping force F reaching the specified reference value (e.g., F2 or F2′) falls within the allowable range Δt. The error E is, for example, the error generated when converting the set value of the clamping force F into the set value of the crosshead position, or the error generated due to the dimensional change of the mold device 800 accompanied by temperature changes.

[0151] like Figure 7 As shown by the solid line, the allowable range setting unit 718 sets the allowable range Δt based on the time t0 at which the actual value of the clamping force F begins to deviate from the reference value after stabilizing with respect to the reference value (e.g., F2 or F2′). Hereinafter, the time t0 at which the actual value of the clamping force F begins to deviate from the reference value after stabilizing with respect to the reference value is referred to as the reference time t0. As described later, the reference time t0 represents the time at which the molding material M reaches the parting surface 830.

[0152] like Figure 7 As shown by the solid line, when the pressure is applied early, the actual value of the clamping force F stabilizes at a reference value (e.g., F2 or F2′) until the molding material M reaches the parting surface 830 of the fixed mold 810 and the moving mold 820. Then, if the molding material M reaches the parting surface 830, the fixed mold 810 and the moving mold 820 begin to open under the filling pressure P1, and the actual value of the clamping force F deviates from the reference value to a higher value. Furthermore, the opening amount of the fixed mold 810 and the moving mold 820 is such that burrs are not generated.

[0153] Furthermore, if the molding material M reaches the parting surface 830, the actual value of the clamping force F may sometimes deviate from the reference value to a lower value. For example, this could occur when the center of the mold assembly 800 or the cavity space 801 is eccentric relative to the center of the fixed pressure plate 110 or the movable pressure plate 120. In this case, if the molding material M reaches the parting surface 830, the deformation of a portion of the connecting rod 140 may be alleviated, and the tensile stress acting on a portion of the connecting rod 140 may decrease. As a result, the detection value of the connecting rod strain detector 141 may sometimes decrease, and the actual value of the clamping force F may also decrease.

[0154] Therefore, the reference timing t0 represents the timing at which the molding material M reaches the parting surface 830. For example, as... Figure 7As shown, the allowable range setting unit 718 sets the allowable range Δt in a manner that includes timing t0. The allowable range Δt includes timing t0 as a central value, but it can also include timing t0 as an upper or lower limit value. Furthermore, the allowable range Δt may not include timing t0; for example, it may be set to a range earlier than timing t0.

[0155] The allowable range Δt is set, for example, for each mold assembly 800. The allowable range Δt can be set and changed. Furthermore, the allowable range Δt can be set without using a reference timing t0. For example, the control device 700 can use an image of the molded part to detect the presence of burrs and burns, and automatically set the allowable range Δt based on the detection results. Alternatively, operators can visually confirm the presence of burrs and burns and input values ​​in the input field on the screen, thereby manually setting the allowable range Δt.

[0156] like Figure 7 As shown by the dashed line, when the timing reaches the target value falls within the allowable range Δt, the generation of spikes can be suppressed and the pressure boosting timing can be set as far back as possible, thereby also suppressing the generation of gas burning. Therefore, when the timing reaches the target value falls within the allowable range Δt, the determination unit 716 determines that the pressure boosting timing is appropriate. On the other hand, when the timing reaches the target value does not fall within the allowable range Δt, the determination unit 716 determines that the pressure boosting timing is inappropriate.

[0157] Furthermore, in this modified example, the judgment unit 716 determines whether the boost timing is appropriate, but the appropriateness of the boost timing can also be determined by an operator. That is, in this modified example, the appropriateness of the boost timing is determined automatically, but it can also be determined manually. When manually determining whether the boost timing is appropriate, for example, the display control unit 720 of the control device 700 (see reference) Figure 3 The monitoring results of the monitoring unit 715 are displayed on the display device 760.

[0158] By observing the monitoring results displayed on the monitoring unit 715 of the display device 760, the operator can determine whether the pressure boosting timing is appropriate. The content displayed on the display device 760 includes, for example, the waveform of the actual value of the clamping force F, the timing of reaching the target, and the allowable range Δt (for reference). Figure 7 Alternatively, the content displayed on the display device 760 may only include whether the timing falls within the allowable range Δt.

[0159] In this modified example, the setting change unit 717 changes the boost timing setting so that the arrival timing falls within the allowable range Δt. When the arrival timing is earlier than the allowable range Δt, the setting change unit 717 changes the boost timing setting to be delayed. On the other hand, when the arrival timing is later than the allowable range Δt, the setting change unit 717 changes the boost timing setting to be advanced. The setting change amount can be a predetermined amount or an amount corresponding to the deviation of the arrival timing from the allowable range Δt. In the latter case, the greater the deviation of the arrival timing from the allowable range Δt, the greater the setting change amount.

[0160] The setting change unit 717 repeatedly changes the pressure boosting timing setting until the timing falls within the allowable range. This suppresses the generation of spikes and, by delaying the pressure boosting timing as much as possible, also suppresses gas burning. It can automatically set the pressure boosting timing, which was previously only possible for skilled users.

[0161] The setting modification unit 717, for example, changes the setting of the pressure boosting timing in the (n+1)th molding cycle based on the arrival timing in the nth (n is a natural number greater than or equal to 1) molding cycle. In the (n+1)th molding cycle and subsequent molding cycles, it can suppress the generation of burrs and postpone the pressure boosting timing as much as possible, thereby also suppressing the generation of gas burning.

[0162] Furthermore, in this modified example, the setting change unit 717 changes the boost timing setting, but the boost timing setting can also be changed by an operator. That is, in this modified example, the boost timing setting is changed automatically, but the boost timing setting can also be changed manually.

[0163] For example, while observing the monitoring results displayed on the monitoring unit 715 of the display device 760, the operator changes the boost timing setting. This setting change is performed by the operator entering the boost timing in the input field of the screen. The operator can repeatedly change the boost timing setting and measure the timing reached for each boost timing. The operator enters the boost timing that falls within the allowable range Δt as the boost timing for the next subsequent boost timing in the input field of the screen.

[0164] The above describes the embodiments of the control device and control method for the injection molding machine according to the present invention. However, the present invention is not limited to the above embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations can be made within the scope of the technical solution described. 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 mold closing control unit changes the set value of the mold closing force from a first set value to a second set value that is greater than the first set value during a predetermined pressure increase timing midway through the filling process of filling molding material into the mold device in the mold closing process. The monitoring unit monitors the change in the actual value of the clamping force as the set value of the clamping force changes; and The judgment unit determines whether the boost timing is appropriate based on the monitoring results of the monitoring unit.

2. A control device for an injection molding machine, comprising: The mold closing control unit changes the set value of the mold closing force from a first set value to a second set value that is greater than the first set value during a predetermined pressure increase timing midway through the filling process of filling molding material into the mold device in the mold closing process. The monitoring unit monitors the change in the actual value of the clamping force as the set value of the clamping force changes; and The setting change unit changes the setting of the boost timing based on the monitoring results of the monitoring unit.

3. A control device for an injection molding machine, comprising: The mold closing control unit changes the set value of the mold closing force from a first set value to a second set value that is greater than the first set value during a predetermined pressure increase timing midway through the filling process of filling molding material into the mold device in the mold closing process. The monitoring unit monitors the change in the actual value of the clamping force as the set value of the clamping force changes; and The determination unit determines whether the timing of the actual value of the clamping force reaching the predetermined reference value is permitted.

4. A control device for an injection molding machine, comprising: The mold closing control unit changes the set value of the mold closing force from a first set value to a second set value that is greater than the first set value during a predetermined pressure increase timing midway through the filling process of filling molding material into the mold device in the mold closing process. The monitoring unit monitors the change in the actual value of the clamping force as the set value of the clamping force changes; and The setting change unit changes the setting of the pressure boosting time according to the arrival time when the actual value of the clamping force reaches the predetermined reference value.

5. A control device for an injection molding machine, comprising: The mold closing control unit changes the set value of the mold closing force from a first set value to a second set value that is greater than the first set value during a predetermined pressure increase timing midway through the filling process of filling molding material into the mold device in the mold closing process. The monitoring unit monitors the change in the actual value of the clamping force as the set value of the clamping force changes; and The judgment unit determines, based on the reference timing at which the actual value of the clamping force deviates from the specified reference value, whether the arrival timing of the actual value of the clamping force reaching the specified reference value is permitted.

6. A control device for an injection molding machine, comprising: The mold closing control unit changes the set value of the mold closing force from a first set value to a second set value that is greater than the first set value during a predetermined pressure increase timing midway through the filling process of filling molding material into the mold device in the mold closing process. The monitoring unit monitors the change in the actual value of the clamping force as the set value of the clamping force changes; and The judgment unit determines whether the timing at which the actual value of the clamping force begins to stabilize is allowed, based on a reference timing at which the actual value of the clamping force begins to deviate after stabilizing.

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