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

Abstract

To provide a unit for assisting a setting of forward movement restriction of an injection component in a dwelling process.SOLUTION: A control unit of an injection molding machine comprises an injection component disposed in a cylinder for heating a molding material and an injection driving source for moving the injection component forward to pack the molding material in a mold unit. The control unit has a restriction part for restricting the forward movement of the injection component in a dwelling process for controlling the injection driving source such that the actual value of the packing pressure applied to the molding material from the injection component is controlled to a preset value, and a determination part for determining the appropriateness of the setting to be used by the restriction part based on data of a sensor disposed on the mold unit.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] The injection molding machine of Patent Document 1 includes a mold and an injection device. The mold has a movable mold and a fixed mold, and a cavity is formed by these movable and fixed molds. The injection device includes a heating cylinder and a screw placed inside the heating cylinder. By advancing the screw, the molten resin inside the heating cylinder is filled into the cavity. The control system of the injection molding machine of Patent Document 1 controls the drive unit of the injection device based on the difference between the command value and the detected value of the screw position. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 08-164545 Summary of the Invention [Problem to be solved by the invention]

[0004] The injection molding machine includes a cylinder that heats the molding material, an injection member provided inside the cylinder, an injection drive source that fills the molding material into the mold device by advancing the injection member, and a control device that controls the injection drive source. The control device performs a filling process and a pressure holding process, in this order. The filling process is a process of filling the molding material into the mold device by controlling the injection drive source so that the actual value of the movement speed of the injection member becomes a set value. The pressure holding process is a process of replenishing molding material that is insufficient due to cooling contraction within the mold device by controlling the injection drive source so that the actual value of the filling pressure acting on the molding material from the injection member becomes a set value.

[0005] The control device monitors the forward speed of the injection member during the pressure holding process and controls the injection drive source so that the forward speed does not exceed an upper limit. This makes it possible to suppress gas burning. Gas burning is a phenomenon in which the molding material flows into the cavity space in the mold device, compressing the gas in the cavity space and generating heat, which carbonizes the molding material. Conventionally, the forward movement limit of the injection member during the pressure holding process has been set by an expert based on their own experience, and it has been difficult for non-expert workers to set the forward movement limit of the injection member.

[0006] One aspect of the present invention provides a technique that assists in setting a limit on the advancement of the injection member during the packing process.

[0007] Another aspect of the present invention provides a technique for suppressing gas burning. [Means for solving the problem]

[0008] A control device for an injection molding machine according to one aspect of the present invention includes: an injection member provided inside a cylinder that heats a molding material; an injection drive source that moves the injection member forward to fill the molding material into a mold device; a pressure detector provided in an injection device including the injection member and the injection drive source, the pressure detector detecting an actual value of a filling pressure acting on the molding material from the injection member; The control device for an injection molding machine includes: The pressure detected by the pressure detector The actual filling pressure is equal to the set value. Get closer a limiting unit that limits the forward movement of the injection member in a pressure holding step that controls the injection drive source as described above, and a determining unit that determines whether the settings used by the limiting unit are appropriate based on information from a sensor provided in the mold device. or a setting change unit that changes the setting used by the limiting unit based on information from a sensor provided in the mold device. and,

[0009] An injection molding machine according to one aspect of the present invention control The device includes an injection member provided inside a cylinder that heats a molding material, and an injection drive source that moves the injection member forward to fill the molding material into the mold device; a pressure detector provided in an injection device including the injection member and the injection drive source, the pressure detector detecting an actual value of a filling pressure acting on the molding material from the injection member; The control device for an injection molding machine includes: The pressure detected by the pressure detector The actual filling pressure is equal to the set value. Get closerIn the pressure holding step of controlling the injection drive source as described above, a limiting section is provided that limits the forward acceleration of the injection member. [Effects of the Invention]

[0010] According to one aspect of the present invention, the setting can be assisted by determining whether the setting used by the limiting unit is appropriate based on information from a sensor provided in the mold device.

[0011] According to another aspect of the present invention, by limiting the forward acceleration of the injection member, compression of the gas can be suppressed, and gas burning can be suppressed. [Brief explanation of the drawings]

[0012] [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 functional block diagram illustrating an example of components of the control device. [Figure 4] FIG. 4 is a diagram showing an example of a molding cycle process. [Figure 5] FIG. 5 is a diagram illustrating an example of the relationship between the injection control unit and the restriction unit. [Figure 6] FIG. 6 is a cross-sectional view showing an example of molding material flowing into the inside of a mold device. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same reference numerals, and the description thereof may be omitted.

[0014] (injection molding machine) FIG. 1 is a diagram showing a state of an injection molding machine according to an embodiment when mold opening is completed. FIG. 2 is a diagram showing a state of an injection molding machine according to an 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.

[0015] 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.

[0016] (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.

[0017] The mold clamping device 100 performs mold closing, pressure increase, 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.

[0018] 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 a fixed mold 810 is attached, a movable platen 120 to which a movable mold 820 is attached, and a movement mechanism 102 that moves the movable platen 120 relative to the fixed platen 110 in the mold opening and closing direction.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] The configuration of the 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 the third link 154 may be connected to the node between the first link 152 and the second link 153.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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 (e.g., clamping position) or the position of the movable platen.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] The rotational drive force transmission unit 185 is composed of, 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 composed of a belt, a pulley, or the like instead of gears.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] The mold clamping unit 100 of this embodiment is a horizontal type in which the mold opening and closing direction is horizontal, but it may also be a vertical type in which the mold opening and closing direction is vertical.

[0050] Although the mold clamping unit 100 of this embodiment has a mold clamping motor 160 as a drive unit, 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.

[0051] (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.

[0052] 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).

[0053] 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.

[0054] 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 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. Balls or rollers may be interposed between the screw shaft and the screw nut.

[0055] The ejector unit 200 performs an ejection process under the control of the control unit 700. In the ejection process, the ejector rod 210 is advanced from the standby position to the ejection position at a set moving speed, thereby advancing the ejector plate 826 and ejecting the molded product. After that, the ejector motor is driven to retract the ejector rod 210 at the set moving speed, and the ejector plate 826 is retracted to the original standby position.

[0056] 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 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.

[0057] (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.

[0058] 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 a cavity space 801 in the mold unit 800 with a molding material. 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 a load transmitted between the injection motor 350 and the screw 330.

[0059] 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 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 first heater 313, such as a band heater, and a first temperature detector 314 are provided on the outer periphery of cylinder 310, ahead of cooler 312.

[0060] Cylinder 310 is divided into a plurality of zones in the axial direction (e.g., X-axis direction) of cylinder 310. A first heater 313 and a first temperature detector 314 are provided in each of the plurality of zones. A set temperature is set in each of the plurality of zones, and control device 700 controls first heater 313 so that the temperature detected by first temperature detector 314 becomes the set temperature.

[0061] The nozzle 320 is provided at the front end of the cylinder 310 and is pressed against the mold device 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] The pressure detector that detects the pressure of the molding material is not limited to the load detector 360, and a general detector can 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. The mold internal pressure sensor is installed inside the mold device 800.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] It should be noted 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.

[0081] 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.

[0082] 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.

[0083] Although the injection device 300 of this embodiment is of an in-line screw type, it 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.

[0084] 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.

[0085] (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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] (Control device) The control device 700 is configured, for example, by a computer, and as shown in Figures 1 and 2, has 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 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.

[0094] The control device 700 repeatedly manufactures 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, such as 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."

[0095] 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.

[0096] It should be noted that, in order to shorten the molding cycle time, multiple processes may be performed simultaneously. 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 for opening and closing 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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, by using 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 screen of the touch panel 770 may also 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 signals corresponding to the input operations to the control device 700. This allows, for example, a user to operate the operation units provided on the screen while checking information displayed on the screen to perform settings of the injection molding machine 10 (including input of setting values). The user can also operate the operation units provided on the screen to cause the injection molding machine 10 to perform operations corresponding to the operation units. The operation of the injection molding machine 10 may be, for example, the operation (including stopping) of the clamping device 100, the ejector device 200, the injection device 300, the moving device 400, etc. The operation of the injection molding machine 10 may also be the switching of a screen displayed on the touch panel 770 serving as the display device 760, etc.

[0101] 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).

[0102] (Details of the control device) Next, an example of the components of the control device 700 will be described with reference to FIG. 3. Note that each functional block shown in FIG. 3 is conceptual and does not necessarily have to be physically configured as shown. All or part of each functional block can be configured by functionally or physically distributing or integrating in any unit. All or any part of the processing functions performed by each functional block can be realized by a program executed by a CPU, or can be realized as hardware using wired logic.

[0103] As shown in FIG. 3, the control device 700 includes, for example, a mold clamping control unit 711, an ejector control unit 712, an injection control unit 713, and a metering control unit 714. The mold clamping control unit 711 controls the mold clamping unit 100 and performs the mold closing process, pressurization process, mold clamping process, depressurization process, and mold opening process shown in FIG. 4. The ejector control unit 712 controls the ejector unit 200 and performs the ejection process. The injection control unit 713 controls the injection drive source of the injection unit 300 and performs the injection process. The injection drive source is, for example, the injection motor 350, but may also be a hydraulic cylinder or the like. The injection process includes a filling process and a pressure holding process. The injection process is performed during the mold clamping process. The metering control unit 714 controls the metering drive source of the injection unit 300 and performs the metering process. The metering drive source is, for example, the metering motor 340, but may also be a hydraulic pump or the like. The weighing step is carried out during the cooling step.

[0104] The filling process is a process of controlling the injection drive source so that the actual value of the moving speed of the injection member provided inside the cylinder 310 becomes a set value. The filling process is a process of moving the injection member forward to fill the interior of the mold device 800 with the liquid molding material accumulated in front of the injection member. The injection member is, for example, the screw 330 (see FIGS. 1 and 2), but may also be a plunger.

[0105] The moving speed of the injection member is detected using a speed detector. The speed detector is, for example, the injection motor encoder 351. In the filling step, as the injection member moves forward, the pressure acting from the injection member on the molding material (hereinafter also referred to as "filling pressure") increases. The filling step may include a step of temporarily stopping the injection member or a step of retracting the injection member immediately before the pressure holding step.

[0106] The pressure holding process is a process of controlling the injection drive source so that the actual value of the filling pressure becomes the set value. The pressure holding process is a process of pushing the injection member forward to replenish the molding material that is insufficient due to cooling contraction within the mold device 800. The filling pressure is detected using a pressure detector such as the load detector 360. A nozzle pressure sensor or a mold internal pressure sensor may be used as the pressure detector.

[0107] The pressure holding process is controlled by the injection control unit 713. As shown in FIG. 5, the injection control unit 713 has, for example, a speed command creation unit 713a and a current command creation unit 713b. The speed command creation unit 713a creates a speed command based on the deviation between the set value and the actual value of the filling pressure. The current command creation unit 713b creates a current command based on the deviation between the command value and the actual value of the forward speed of the injection member. An injection drive source such as the injection motor 350 is driven in accordance with the current command.

[0108] Next, an example of molding material M flowing into the mold device 800 will be described with reference to Fig. 6. The molding material M is, for example, a resin. The molding material M flows into a cavity space 801 inside the mold device 800. The cavity space 801 is formed at a parting surface 830 between a fixed mold 810 and a movable mold 820. The parting surface 830 is generally called a parting line.

[0109] If the molding material M flows into the cavity space 801 too quickly, the gas in the cavity space 801 will have difficulty escaping to the outside of the mold device 800 through the parting surface 830, etc. This will result in a defect known as gas burning. Gas burning is a phenomenon in which the gas in the cavity space 801 is compressed, generating heat and carbonizing the molding material M.

[0110] When gas burns occur, the gas in the cavity space 801 has difficulty escaping to the outside of the mold device 800 and tends to remain in the cavity space 801, which can result in a defect called a short circuit. A short circuit is a phenomenon in which the molding material M cools and solidifies before filling the entire cavity space 801.

[0111] The flow of molding material M varies depending on, for example, the moving speed of the injection member. The faster the forward speed of the injection member, the faster the flow of molding material M. In the pressure holding process, if the actual value of the filling pressure is smaller than the set value, the injection member is advanced so that the actual value of the filling pressure becomes the set value. If the injection member advances too quickly, the flow of molding material M will become too rapid.

[0112] The sudden advance of the injection member is likely to occur when switching from the filling process to the pressure holding process (so-called V / P switching). During V / P switching, a gap usually remains in the cavity space 801. During V / P switching, if the actual value of the filling pressure is smaller than the set value and the difference between the actual value and the set value is large, the sudden advance of the injection member may occur.

[0113] As shown in FIGS. 3 and 5, the control device 700 has a limiting unit 715. The limiting unit 715 limits the forward movement of the injection member during the pressure holding process. The limiting unit 715 limits the forward movement of the injection member during the pressure holding process, for example, by setting an upper limit on the speed command value created by the speed command creating unit 713a. Even if the actual value of the filling pressure during the pressure holding process is smaller than the set value and the difference between the actual value and the set value is large, the forward movement speed of the injection member will not exceed the upper limit. As a result, gas burning can be suppressed. Not only gas burning but also the occurrence of short circuits can be suppressed.

[0114] Conventionally, gas burning has been suppressed by the restrictor 715 setting an upper limit on the forward speed of the injection member, but this suppression of gas burning has sometimes been insufficient. For example, even if the forward speed is below the upper limit, if the forward acceleration is high, the acceleration at the flow front of the molding material is high, and the gas is easily compressed.

[0115] Therefore, the limiting unit 715 of this embodiment sets an upper limit on the forward acceleration of the injection member during the pressure retention process. The upper limit on the forward speed of the injection member and the upper limit on the forward acceleration are set separately. Even if the actual value of the filling pressure during the pressure retention process is smaller than the set value and the difference between the actual value and the set value is large, the forward acceleration of the injection member will not exceed the upper limit. As a result, gas burning can be suppressed. Not only gas burning, but also the occurrence of short circuits can be suppressed.

[0116] Although the limiting unit 715 of this embodiment sets upper limits on both the forward movement speed and the forward movement acceleration of the injection member during the pressure holding process, there are cases where gas burning can be suppressed by setting an upper limit on either the forward movement speed or the forward movement acceleration. Therefore, it is sufficient for the limiting unit 715 to set an upper limit on at least one of the forward movement speed and the forward movement acceleration of the injection member during the pressure holding process.

[0117] Conventionally, the setting of the forward movement limit of the injection member during the pressure holding process (more specifically, the setting of the upper limit of the forward movement speed) has been performed by an expert based on his or her own experience, and it has been difficult for an operator other than an expert to set the forward movement limit of the injection member.

[0118] 3, the control device 700 has a determination unit 716. The determination unit 716 determines whether the settings used by the limiting unit 715 are appropriate based on information from a sensor 841 provided in the mold device 800. By using the information from the sensor 841 provided in the mold device 800, it is possible to estimate the state of the flow of the molding material M inside the mold device 800 and determine whether the settings used by the limiting unit 715 are appropriate. This makes it possible to assist in setting the forward movement limit of the injection member in the dwelling process.

[0119] The information from the sensor 841 includes, for example, at least one of information on the pressure, temperature, velocity, and acceleration of the gas inside the mold device 800. The more rapid the flow of the molding material M, the greater the pressure, temperature, velocity, and acceleration of the gas. Therefore, the flow status of the molding material M can be estimated from these physical quantities. The sensor 841 includes, for example, at least one of a pressure sensor, a temperature sensor, a velocity sensor, and an acceleration sensor.

[0120] The pressure sensor serving as the sensor 841 detects the pressure of the gas. The pressure sensor is disposed, for example, at the end of the flow path of the molding material. If the detected value of the pressure sensor exceeds an upper limit, the compression rate of the gas inside the mold device 800 is high, which would cause gas burning, and the judgment unit 716 judges that the settings used by the restriction unit 715 are inappropriate. On the other hand, if the detected value of the pressure sensor is equal to or less than the upper limit, the compression rate of the gas inside the mold device 800 is low, which would cause no gas burning, and the judgment unit 716 judges that the settings used by the restriction unit 715 are appropriate.

[0121] The temperature sensor serving as sensor 841 detects the temperature of the gas. The temperature sensor is disposed, for example, at the end of the flow path of the molding material. If the detected value of the temperature sensor exceeds the upper limit, the gas temperature inside the mold device 800 is high and gas burning will occur, and therefore the judgment unit 716 judges that the settings used by the restriction unit 715 are inappropriate. On the other hand, if the detected value of the temperature sensor is equal to or less than the upper limit, the gas temperature inside the mold device 800 is low and gas burning will not occur, and therefore the judgment unit 716 judges that the settings used by the restriction unit 715 are appropriate.

[0122] The velocity sensor serving as sensor 841 detects the velocity of the gas. The velocity sensor is disposed, for example, near the gas passage. The gas passage is, for example, a parting surface 830 between the fixed mold 810 and the movable mold 820, or a pin hole 821 in the movable mold 820. An ejector pin 827, for example, is inserted through the pin hole 821. The ejector pin 827 is moved forward and backward together with an ejector plate 826 (see FIGS. 1 and 2) to eject the molded product formed in the cavity space 801.

[0123] If the detection value of the speed sensor exceeds the upper limit, the speed of the flow front of the molding material is fast, the gas is easily compressed, and gas burning occurs, so the judgment unit 716 judges that the settings used by the restriction unit 715 are inappropriate. On the other hand, if the detection value of the speed sensor is equal to or less than the upper limit, the speed of the flow front of the molding material is slow, the gas is hardly compressed, and gas burning does not occur, so the judgment unit 716 judges that the settings used by the restriction unit 715 are appropriate.

[0124] The acceleration sensor serving as sensor 841 detects the acceleration of the gas. The acceleration sensor is disposed, for example, near the gas passage. If the detected value of the acceleration sensor exceeds an upper limit, the acceleration at the flow front of the molding material is large, the gas is easily compressed, and gas burning occurs. Therefore, the judgment unit 716 judges that the settings used by the restriction unit 715 are inappropriate. On the other hand, if the detected value of the acceleration sensor is equal to or less than the upper limit, the acceleration at the flow front of the molding material is small, the gas is hardly compressed, and gas burning does not occur. Therefore, the judgment unit 716 judges that the settings used by the restriction unit 715 are appropriate. Note that acceleration can also be detected by a velocity sensor.

[0125] The upper limit value to be compared with the detection value of the sensor 841 is set, for example, for each mold device 800. The upper limit value can be changed. For example, an operator manually sets the upper limit value by inputting a numerical value into an input field on the screen. Alternatively, the control device 700 detects the presence or absence of gas burns using an image of the molded product, and automatically sets the upper limit value based on the detection results.

[0126] The sensor 841 acquires the above information at a preset acquisition timing. The acquisition timing is set, for example, as the elapsed time from the start of the filling process or the elapsed time from the start of the pressure holding process. The elapsed time from the start of the pressure holding process is equal to the elapsed time from the V / P switch. When either of the elapsed times reaches the set time, the sensor 841 acquires the above information.

[0127] The acquisition timing may be set based on the position of the flow front of the molding material. When the flow front of the molding material reaches the set position, the sensor 841 acquires the information. Whether the flow front of the molding material has reached the set position is detected, for example, by a presence detection sensor 842 (see FIG. 6). The presence detection sensor 842 detects the presence of the molding material, for example, by the intensity of reflected light.

[0128] The acquisition timing may be set as the time elapsed since the leading edge of the flow of the molding material reaches a set position. When the elapsed time reaches the set time, the sensor 841 acquires the information.

[0129] 3, the control device 700 may have a setting change unit 717. The setting change unit 717 changes the setting used by the limiting unit 715 based on information from a sensor 841. By using the information from the sensor 841 provided in the mold device 800, the state of the flow of the molding material M inside the mold device 800 can be estimated, and the setting can be changed to suit that state. The forward movement limit of the injection member during the pressure holding process, which could previously only be set by an expert, can now be automatically set.

[0130] The pressure sensor serving as the sensor 841 detects the pressure of the gas. If the detected value of the pressure sensor exceeds the upper limit, the compressibility of the gas inside the mold device 800 is high, causing gas burning, so the setting change unit 717 changes the upper limit of at least one of the forward speed and forward acceleration of the injection member in the pressure holding process to a lower value. The amount of setting change may be a fixed amount, or may be an amount corresponding to the difference between the detected value of the pressure sensor and the upper limit. In the latter case, the larger the difference, the larger the amount of setting change. The setting change unit 717 may repeatedly change the setting until the detected value of the pressure sensor becomes equal to or less than the upper limit.

[0131] The temperature sensor serving as sensor 841 detects the temperature of the gas. If the detected value of the temperature sensor exceeds the upper limit, the gas temperature inside the mold device 800 is high, which may cause gas burning. Therefore, the setting change unit 717 changes the upper limit of at least one of the forward speed and forward acceleration of the injection member in the pressure holding process to a lower value. The amount of change in the setting may be a fixed amount, or may be an amount corresponding to the difference between the detected value of the temperature sensor and the upper limit. In the latter case, the greater the difference, the greater the amount of change in the setting. The setting change unit 717 may repeatedly change the setting until the detected value of the temperature sensor falls below the upper limit.

[0132] The velocity sensor serving as sensor 841 detects the velocity of the gas. If the detected value of the velocity sensor exceeds the upper limit, the velocity of the flow front of the molding material is high, the gas is easily compressed, and gas burning occurs. Therefore, the setting change unit 717 changes the upper limit of at least one of the forward velocity and forward acceleration of the injection member in the pressure holding process to a lower value. The amount of setting change may be a fixed amount, or may be an amount corresponding to the difference between the detected value of the velocity sensor and the upper limit. In the latter case, the greater the difference, the greater the amount of setting change. The setting change unit 717 may repeatedly change the setting until the detected value of the velocity sensor falls below the upper limit.

[0133] The acceleration sensor serving as sensor 841 detects the acceleration of the gas. If the detected value of the acceleration sensor exceeds the upper limit, the acceleration at the flow front of the molding material is high, the gas is easily compressed, and gas burning occurs. Therefore, the setting change unit 717 changes the upper limit of at least one of the forward speed and forward acceleration of the injection member during the pressure retention process to a lower value. The amount of setting change may be a fixed amount, or may be an amount corresponding to the difference between the detected value of the acceleration sensor and the upper limit. In the latter case, the greater the difference, the greater the amount of setting change. The setting change unit 717 may repeatedly change the setting until the detected value of the acceleration sensor falls below the upper limit.

[0134] The setting change unit 717 changes the settings used by the limiting unit 715 in molding cycles after the (n+1)th molding cycle, for example, based on information from the sensor 841 in the nth molding cycle (n is a natural number equal to or greater than 1). This makes it possible to suppress the occurrence of gas burns in molding cycles after the (n+1)th molding cycle. The setting change unit 717 may repeatedly change the settings until the detection value of the sensor 841 falls within a desired range.

[0135] The setting change unit 717 may change the setting used by the limiting unit 715 in the nth molding cycle based on information from the sensor 841 in the nth molding cycle (n is a natural number equal to or greater than 1). The occurrence of gas burns can be suppressed in the nth molding cycle. In other words, the occurrence of gas burns can be suppressed in real time. The setting change unit 717 may repeatedly change the setting until the detection value of the sensor 841 falls within the desired range.

[0136] In this embodiment, the settings used by the limiting unit 715 are changed by the setting change unit 717, but the settings used by the limiting unit 715 may also be changed by an operator. That is, in this embodiment, the settings are changed automatically, but the settings may also be changed manually. When the settings are changed manually, for example, the display control unit 720 (see FIG. 3) of the control device 700 displays information from the sensor 841 on the display device 760.

[0137] The operator changes the settings used by the limiting unit 715 while viewing, for example, the information from the sensor 841 displayed on the display device 760. The change is made by the operator inputting an upper limit value for at least one of the forward speed and forward acceleration of the injection member in the pressure holding process into an input field on the screen. The operator may repeatedly change the settings until the detection value of the sensor 841 falls within the desired range.

[0138] While the embodiments of the injection molding machine control device and injection molding machine control method according to the present invention have been described above, 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]

[0139] 10 injection molding machine 310 cylinder 330 Screw (injection member) 350 Injection motor (injection drive source) 700 control device 715 Restricted Section 716 Judgment Department 800 mold equipment

Claims

1. A control device for an injection molding machine, comprising: an injection member provided inside a cylinder that heats a molding material; an injection drive source that moves the injection member forward to fill the molding material into a mold device; and a pressure detector that is provided in an injection device including the injection member and the injection drive source and that detects an actual value of a filling pressure acting on the molding material from the injection member, a limiting unit that limits the forward movement of the injection member in a pressure holding step of controlling the injection drive source so that the actual value of the filling pressure detected by the pressure detector approaches a set value; a determination unit that determines whether the settings used by the limiting unit are appropriate based on information from a sensor provided in the mold device, or a setting change unit that changes the settings used by the limiting unit based on information from a sensor provided in the mold device; A control device for an injection molding machine having the above.

2. 2. The control device for an injection molding machine according to claim 1, wherein the limiting unit sets an upper limit value for at least one of a forward speed and a forward acceleration of the injection member in the pressure holding step, and the determining unit determines whether the upper limit value is appropriate.

3. 3. The control device for an injection molding machine according to claim 1, wherein the information from the sensor includes at least one of information on pressure, temperature, velocity, and acceleration of gas inside the mold device.

4. 4. The control device for an injection molding machine according to claim 1, wherein the setting change unit changes the setting used by the limiting unit in an n+1th or later molding cycle based on the information from the sensor in an nth molding cycle (n is a natural number equal to or greater than 1).

5. 4. The control device for an injection molding machine according to claim 1, wherein the setting change unit changes the setting used by the limiting unit in an n-th molding cycle based on the information from the sensor in the n-th molding cycle (n is a natural number equal to or greater than 1).

6. 6. The control device for an injection molding machine according to claim 1, further comprising a display control unit that displays the information from the sensor on a display device.

7. A control device for an injection molding machine, comprising: an injection member provided inside a cylinder that heats a molding material; an injection drive source that moves the injection member forward to fill the molding material into a mold device; and a pressure detector that is provided in an injection device including the injection member and the injection drive source and that detects an actual value of a filling pressure acting on the molding material from the injection member, a limiting unit that limits the forward acceleration of the injection member during a pressure holding process that controls the injection drive source so that the actual value of the filling pressure detected by the pressure detector approaches a set value.

8. A control method for an injection molding machine including an injection member provided inside a cylinder that heats a molding material, an injection drive source that fills the molding material into a mold device by moving the injection member forward, and a pressure detector that is provided in an injection device including the injection member and the injection drive source and that detects an actual value of a filling pressure acting on the molding material from the injection member, comprising: a step of limiting forward movement of the injection member in a pressure holding step of controlling the injection drive source so that the actual value of the filling pressure detected by the pressure detector approaches a set value; a step of determining whether a setting used to limit the advancement of the injection member is appropriate based on information from a sensor provided in the mold device, or a step of changing the setting used to limit the advancement of the injection member based on information from a sensor provided in the mold device; A control method for an injection molding machine, comprising:

9. A control method for an injection molding machine including an injection member provided inside a cylinder that heats a molding material, an injection drive source that fills the molding material into a mold device by moving the injection member forward, and a pressure detector that is provided in an injection device including the injection member and the injection drive source and that detects an actual value of a filling pressure acting on the molding material from the injection member, comprising: A control method for an injection molding machine, comprising a step of limiting forward acceleration of the injection member in a pressure holding step of controlling the injection drive source so that an actual value of the filling pressure detected by the pressure detector approaches a set value.

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