Injection molding machine control device, injection molding machine, and injection molding machine control method

Abstract

To provide a technique for reducing an impact that occurs when retreating an injection member in a pressure holding process.SOLUTION: Provided is a controller of an injection molding machine comprising: an injection member provided inside a cylinder for heating a molding material; and an injection driving source which fills the molding material into a molding machine by advancing the injection member. The controller has a limiting part which limits retreating speed of the injection member to a preset limited value or less in a pressure holding process of controlling a filling pressure which works from the injection member to the molding material. The limiting part, when the position of the injection member reaches a preset deceleration starting position during retreat of the injection member in the pressure holding process, controls the retreating speed of the injection member to a speed smaller than the limited value.SELECTED DRAWING: Figure 7

Description

[Technical field]

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

[0002] The injection molding machine includes a cylinder for heating the molding material, an injection member provided inside the cylinder, an injection drive source for moving the injection member forward to fill the molding material into the inside of the mold device, and a control device for controlling the injection drive source (see Patent Document 1). The control device performs a filling process and a pressure holding process in this order. The filling process is a process for filling the molding material into the mold device by controlling the injection drive source so that the actual value of the moving speed of the injection member becomes a set value. The pressure holding process is a process for replenishing the molding material that is insufficient due to cooling contraction in 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.

[0003] The switch from the filling process to the pressure holding process is also called V / P switch. If the actual value of the filling pressure is greater than the set value after the V / P switch, the injection member is retracted so that the actual value of the filling pressure becomes smaller. Patent Document 1 describes that by setting a limit value on the retraction speed of the injection member in the pressure holding process, it is possible to eliminate the adverse effect on the quality of the molded product caused by the screw retracting at high speed in the pressure holding process. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3917459 Summary of the Invention [Problem to be solved by the invention]

[0005] A nozzle is provided at the tip of the cylinder. The nozzle injects the molding material heated by the cylinder into the inside of the mold device. If the temperature of at least one of the nozzle and the cylinder is too low, the viscosity of the molding material exceeds the viscosity suitable for the injection pressure, and so-called nozzle clogging occurs. Nozzle clogging is a phenomenon in which the molding material is not injected from the nozzle even when the filling process is started and the injection member is advanced.

[0006] When the nozzle becomes clogged, the actual filling pressure is greater than the set value after V / P switching, and the deviation is large, so there is a risk that the injection member will be retracted to the rearmost position of its movable range. If the injection member is retracted to the rearmost position, an impact will be applied to the mechanical elements that make up the injection device, shortening the life of the mechanical elements.

[0007] An example of a mechanical element is a ball screw. The ball screw converts the rotational motion of the injection motor into the linear motion of the injection member. The ball screw includes a screw shaft, a screw nut, and balls that roll between the screw shaft and the screw nut. When the screw nut reaches the stroke end of the screw shaft, the injection member reaches a retreat limit position, and the retreat of the injection member stops.

[0008] The reason why the injection member is retracted to the retract limit position is not limited to nozzle clogging. For example, the same problem can occur when the molded product is not properly removed. When the molded product is not properly removed, the filling process is started with the molded product still inside the mold device. Therefore, after the V / P switch, the actual value of the filling pressure is greater than the set value, and the deviation is large, so that the injection member may be retracted to the retract limit position of its movable range.

[0009] One aspect of the present invention provides a technique for reducing the impact caused by the retraction of the injection member during the pressure holding step. [Means for solving the problem]

[0010] A control device for an injection molding machine according to one aspect of the present invention is a control device for an injection molding machine including an injection member provided inside a cylinder that heats a molding material, and an injection drive source that advances the injection member to fill the molding material into a mold device. The control device has a limiting unit that limits a retreat speed of the injection member to a preset limit value or less in a pressure holding process that controls a filling pressure acting on the molding material from the injection member. When the position of the injection member reaches a preset deceleration start position during the retreat of the injection member in the pressure holding process, the limiting unit controls the retreat speed of the injection member to a speed less than the limit value. Effect of the Invention

[0011] According to one aspect of the present invention, when the position of the injection member reaches a preset deceleration start position during the retraction of the injection member in the pressure holding step, the retraction speed of the injection member is controlled to a speed lower than the limit value. As a result, even if the injection member is retracted to the retract limit position, the retraction speed of the injection member at that time is low and the impact is small. Therefore, the impact can be reduced. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing a state when mold opening of an injection molding machine according to an embodiment is completed. [Diagram 2] FIG. 2 is a diagram showing a state during mold clamping of the injection molding machine according to one embodiment. [Diagram 3] FIG. 3 is a functional block diagram of an example of components of the control device. [Figure 4] FIG. 4 is a diagram showing an example of steps in a molding cycle. [Diagram 5] FIG. 5 is a diagram illustrating an example of an injection control unit. [Figure 6] FIG. 6 is a diagram illustrating an example of a limiting unit. [Figure 7] FIG. 7 is a diagram showing an example of the change over time of the screw speed, the filling pressure, and the screw position. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment 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, the Y-axis direction, and the Z-axis direction are perpendicular to each other. The X-axis direction and the Y-axis direction represent the horizontal direction, and the Z-axis direction represents the vertical direction. 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 operation side, and the positive side of the Y-axis direction is called the anti-operation side.

[0015] As shown in FIG. 1 and FIG. 2, the injection molding machine 10 includes a mold clamping device 100 that opens and closes a mold device 800, an ejector device 200 that ejects a molded product molded by the mold device 800, an injection device 300 that injects a molding material into the mold device 800, a moving device 400 that moves the injection device 300 forward and backward relative to the mold device 800, a control device 700 that controls each component of the injection molding machine 10, and a frame 900 that supports each component of the injection molding machine 10. The frame 900 includes a mold clamping device frame 910 that supports the mold clamping device 100, and an injection device frame 920 that supports the injection device 300. The mold clamping device frame 910 and the injection device frame 920 are each installed on the floor 2 via a leveling adjuster 930. The control device 700 is disposed in the internal space of the injection device frame 920. Hereinafter, each component of the injection molding machine 10 will be described.

[0016] (mold clamping device) In the description of the clamping unit 100, the moving direction of the movable platen 120 during mold closing (for example, the positive direction of the X-axis) is the front, and the moving direction of the movable platen 120 during mold opening (for example, the negative direction of the X-axis) is 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 apparatus 100 is, for example, a horizontal type, and the mold opening and closing direction is horizontal. The mold clamping apparatus 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 in the mold opening and closing direction relative to the fixed platen 110.

[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 disposed 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 advances and retreats the movable platen 120 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 disposed at a distance from the fixed platen 110, a tie bar 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 and 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 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 bar 140 connects the fixed platen 110 and the toggle support 130 at a distance 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 of 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 for detecting the mold clamping force, etc.

[0025] In this embodiment, the tie bar strain detector 141 is used as a 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 the strain gauge type, and may be a piezoelectric type, a capacitive type, a hydraulic type, an electromagnetic type, or the like, and the attachment position is 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 stretch 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 stretchable by a pin or the like. The first link 152 is attached to the movable platen 120 by a pin or the like so as to be swingable. The second link 153 is attached to the toggle support 130 by a pin or the like so as to be swingable. The second link 153 is attached to the crosshead 151 via a third link 154. When the crosshead 151 is advanced or retreated relative to the toggle support 130, the first link 152 and the second link 153 bend and stretch, 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 the number of joints in each link group is five in Figures 1 and 2, it may be four, and one end of the third link 154 may be connected to a joint 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 advances and retreats the crosshead 151 relative to the toggle support 130, thereby bending and extending the first link 152 and the second link 153 and advancing and retreating the movable platen 120 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 increase process, a mold clamping process, a pressure release 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 moving 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 moving speed of the crosshead 151 are detected by 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 devices 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 devices 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 in which the insert material and the molding material are integrated is obtained.

[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. After that, the ejector unit 200 ejects the molded product from the movable mold 820.

[0038] The setting conditions in the mold closing process, the pressure increase process, and the mold clamping process are set together as a series of setting conditions. For example, the moving speed and position of the crosshead 151 in the mold closing process and the pressure increase process (including the mold closing start position, the moving speed switching position, the mold closing completion position, and the mold clamping position) and the mold clamping force are set together as a series of setting conditions. The mold closing start position, the moving speed switching position, the mold closing completion position, and the mold clamping position are arranged in this order from the rear side to the front, and represent the start point and the end point of the section in which the moving speed is set. The moving speed is set for each section. There may be one or more moving speed switching positions. The moving 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 in the depressurization process and mold opening process are set in the same 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 in 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 the mold closing completion position may be the same position. Also, the mold opening completion position and the mold closing start position may be the same position.

[0040] Note 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. Moreover, instead of the position of the crosshead 151 (e.g., the mold clamping position) or the position of the movable platen 120, the mold clamping force may be set.

[0041] Incidentally, the toggle mechanism 150 amplifies the driving force of the mold clamping motor 160 and transmits it to the movable platen 120. The amplification ratio is also called the toggle ratio. The toggle ratio changes according to 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 ratio is maximum.

[0042] When the thickness of the mold device 800 changes due to replacement of the mold device 800 or a temperature change of the mold device 800, a mold thickness adjustment is performed so that a predetermined clamping force is obtained during mold clamping. In the 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 mold touch time when the movable mold 820 touches the fixed mold 810.

[0043] The mold clamping device 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 on the toggle support 130, and a mold thickness adjustment motor 183 that rotates the screw nut 182 screwed onto the screw shaft 181.

[0044] The screw shaft 181 and the 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 multiple screw nuts 182 via a rotational driving force transmission unit 185. The multiple screw nuts 182 can be rotated synchronously. Note that by changing the transmission path of the rotational driving force transmission unit 185, it is also possible to rotate the multiple screw nuts 182 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 the 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 the 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 interval 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 distance L is detected using a mold thickness adjustment motor encoder 184. The mold thickness adjustment motor encoder 184 detects the amount of rotation and the 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 distance L. Note that the toggle support position detector that detects the position of the toggle support 130 and the distance detector that detects the distance L are not limited to the mold thickness adjustment motor encoder 184, and general detectors can be used.

[0048] The mold clamping apparatus 100 may have a mold temperature regulator that regulates the temperature of the mold apparatus 800. The mold apparatus 800 has a flow path for a temperature control medium therein. The mold temperature regulator regulates the temperature of the mold apparatus 800 by regulating the temperature of the temperature control medium supplied to the flow path of the mold apparatus 800.

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

[0050] Although the mold clamping apparatus 100 of the present 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 apparatus 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 unit 200, similar to the description of the mold clamping unit 100, the direction of movement of the movable platen 120 during mold closing (e.g., the positive direction of the X-axis) will be referred to as the forward direction, and the direction of movement of the movable platen 120 during mold opening (e.g., the negative direction of the X-axis) will be referred to as the rearward direction.

[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 the linear motion of the ejector rod 210. The motion conversion mechanism includes a screw shaft and a screw nut that screws onto the screw shaft. A ball or roller may be interposed between the screw shaft and the screw nut.

[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 advances from the standby position to the ejection position at a set moving speed, thereby advancing the ejector plate 826 and ejecting the molded product. After that, the ejector motor is driven to move the ejector rod 210 backward at the set moving speed, and the ejector plate 826 backward to the original standby position.

[0056] The position and moving speed of the ejector rod 210 are detected, for example, by using 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 moving speed detector that detects the moving 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 device 300 is installed on a slide base 301, and the slide base 301 is disposed so as to be movable forward and backward with respect to the injection device frame 920. The injection device 300 is disposed so as to be movable forward and backward with respect to the mold device 800. The injection device 300 touches the mold device 800 and fills a cavity space 801 in the mold device 800 with a molding material. The injection device 300 has, for example, a cylinder 310 for heating the molding material, a nozzle 320 provided at the front end of the cylinder 310, a screw 330 disposed in the cylinder 310 so as to be movable forward and backward and rotatable, 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 a load transmitted between the injection motor 350 and the screw 330.

[0059] The cylinder 310 heats the molding material supplied to the inside from a supply port 311. The molding material includes, for example, a resin. The molding material is formed, for example, in the shape of pellets, and is supplied to the supply port 311 in a solid state. The supply port 311 is formed at the rear of the cylinder 310. A cooler 312 such as a water-cooled cylinder is provided on the outer periphery of the rear of the cylinder 310. A first heater 313 such as a band heater and a first temperature detector 314 are provided on the outer periphery of the cylinder 310, forward of the cooler 312.

[0060] The cylinder 310 is divided into a plurality of zones in the axial direction (e.g., the X-axis direction) of the 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 the control device 700 controls the first heater 313 so that the detected temperature of the 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 in 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 heat from the cylinder 310. As the liquid molding material is sent forward 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 check ring 331 is attached to the front of the screw 330 so as to be movable back and forth as a check valve for preventing the backflow of molding material 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 backward relatively to the screw 330 to a blocking position (see FIG. 2) where the flow path of the molding material is blocked. 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 relatively to the screw 330 to an open position (see FIG. 1) where the flow path of the molding material is opened. As a result, the molding material is 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 between the open position and the closed position relative to the screw 330.

[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 the 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 a 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 for detecting the pressure of the molding material is not limited to the load detector 360, and a general detector may be used. For example, a nozzle pressure sensor or a mold internal pressure sensor may be used. The nozzle pressure sensor is installed in the nozzle 320. 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, and the like 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 rotation speed, and the molding material is sent forward along the spiral groove of the screw 330. As a result, the molding material is gradually melted. As the liquid molding material is sent forward of the screw 330 and accumulates at the front of the cylinder 310, the screw 330 is moved backward. The rotation speed of the screw 330 is detected, for example, by 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 rotation speed detector that detects the rotation 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, a set back pressure may be applied to the screw 330 by driving the injection motor 350. The back pressure on the screw 330 is detected, for example, by using a load detector 360. When the screw 330 retracts to the metering completion position and a predetermined amount of molding material is accumulated in front of the screw 330, the metering process is completed.

[0076] The position and rotation 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 rotation 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 in which the rotation speed is set. The rotation speed is set for each section. There may be one or more rotation speed switching positions. The rotation speed switching positions do not have to be set. In addition, a back pressure is set for each section.

[0077] In the filling step, 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, for example, by using 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, switching from the filling step to the pressure holding step (so-called V / P switching) is performed. The position where the V / P switching is performed is also called the V / P switching 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 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 positions do 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 moving 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 moving speed. On the other hand, when the pressure of the screw 330 exceeds the set pressure, the screw 330 is advanced at a moving speed slower than the set moving speed so that the pressure of the screw 330 is equal to or lower than the set pressure, for the purpose of protecting the mold.

[0080] After the position of the screw 330 reaches the V / P switching position in the filling process, the screw 330 may be temporarily stopped at the V / P switching position, and then the V / P switching may be performed. Immediately before the V / P switching, instead of stopping the screw 330, the screw 330 may be moved forward or backward at a slow speed. In addition, 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 holding pressure step, the injection motor 350 is driven to push the screw 330 forward, and the pressure of the molding material at the front end of the screw 330 (hereinafter also referred to as "holding pressure") is maintained at a set pressure, and the molding material remaining in the cylinder 310 is pushed toward the mold device 800. The molding material that is insufficient due to cooling contraction in the mold device 800 can be replenished. The holding pressure is detected, for example, by a load detector 360. The set value of the holding pressure may be changed depending on the elapsed time from the start of the holding pressure step. The holding pressure and the holding time for which the holding pressure is held in the holding pressure step may each be set multiple times, or may be set collectively 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 is started. In the cooling step, the molding material in the cavity space 801 is solidified. A measuring step may be performed during the cooling step in order to shorten the molding cycle time.

[0083] Incidentally, the injection device 300 of this embodiment is of an in-line screw type, but may be of a pre-plastication type or the like. An injection device of the pre-plastication type 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 as to be rotatable but unable to move forward or backward, or a screw is disposed so as to be rotatable and able to move forward or backward. Meanwhile, a plunger is disposed in the injection cylinder so as to be able to move forward or backward.

[0084] Furthermore, the injection device 300 of this embodiment is a horizontal type in which the axial direction of the cylinder 310 is horizontal, but may be a vertical type in which the axial direction of the cylinder 310 is vertical. A mold clamping device to be combined with the vertical injection device 300 may be either a vertical type or a horizontal type. Similarly, a mold clamping device to be combined with the horizontal injection device 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 (for example, the negative X-axis direction) is the front, and the moving direction of the screw 330 during metering (for example, the positive X-axis direction) is the rear.

[0086] The moving device 400 moves the injection device 300 forward and backward relative to the mold device 800. In addition, the moving device 400 presses the nozzle 320 against the mold device 800 to generate a 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 pump that can rotate in both directions, 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 port, thereby generating hydraulic pressure. Note that the hydraulic pump 410 can also draw in hydraulic fluid from a tank and discharge the hydraulic fluid from one of the first port 411 and the second port 412.

[0088] The motor 420 operates the hydraulic pump 410. The motor 420 drives the hydraulic pump 410 with a rotational direction and 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 inside 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 die 810. The front chamber 435 functions as a pressure chamber that generates a nozzle touch pressure of the nozzle 320 by the pressure of the hydraulic fluid supplied from the hydraulic pump 410.

[0091] 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 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 has a CPU (Central Processing Unit) 701, a storage medium 702 such as a memory, an input interface 703, and an output interface 704 as shown in Fig. 1 and Fig. 2. The control device 700 performs various controls by causing the CPU 701 to execute a program stored in the storage medium 702. The control device 700 also receives signals from the outside via the input interface 703, and transmits signals to the outside via the output interface 704.

[0094] The control device 700 repeatedly performs a metering process, a mold closing process, a pressure increase process, a mold clamping process, a filling process, a pressure holding process, a cooling process, a pressure release process, a mold opening process, and an ejection process, thereby repeatedly manufacturing a molded product. A series of operations for obtaining a molded product, for example, an operation from the start of a metering process to the start of the next metering process, is also called a "shot" or a "molding cycle." The time required for one shot is also called a "molding cycle time" or a "cycle time."

[0095] One molding cycle includes, for example, a metering process, a mold closing process, a pressure increase process, a mold clamping process, a filling process, a pressure holding process, a cooling process, a pressure release 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 pressure release process coincides with the start of the mold opening process.

[0096] In addition, in order to shorten the molding cycle time, a plurality of 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. In the case where an opening / closing 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 if the opening / closing valve closes the flow path of the nozzle 320.

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

[0099] Furthermore, after the metering step is completed, a post-metering suck-back step may be performed in which the screw 330 is moved back to a preset filling start position (also called the "injection start position") before the filling step is started. This can reduce the pressure of the molding material accumulated in front of the screw 330 before the filling step is started, and can prevent the molding material from leaking from the nozzle 320 before the filling step is started.

[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 configured, for example, by a touch panel 770 and may be integrated. The touch panel 770 as the display device 760 displays a screen under the control of the control device 700. For example, the screen of the touch panel 770 may display information such as the settings of the injection molding machine 10 and the current state of the injection molding machine 10. In addition, for example, an operation unit such as a button that accepts an input operation by a user and an input field may be displayed on the screen of the touch panel 770. The touch panel 770 as the operation device 750 detects an input operation on the screen by the user and outputs a signal corresponding to the input operation to the control device 700. Thereby, for example, the user can operate the operation unit provided on the screen while checking the information displayed on the screen to perform settings of the injection molding machine 10 (including input of a setting value). In addition, the user can operate the operation unit provided on the screen to perform an operation of the injection molding machine 10 corresponding to the operation unit. 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 be the switching of a screen displayed on the touch panel 770 serving as the display device 760, etc.

[0101] Incidentally, the operation device 750 and the display device 760 of this embodiment have been described as being integrated as the touch panel 770, but 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 (Y-axis negative direction) of the mold clamping unit 100 (more specifically, the fixed platen 110).

[0102] (Control device details) Next, an example of 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 a part of each functional block can be functionally or physically distributed and integrated in any unit. All or any part of each processing function 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 device 100 and performs the mold closing process, the pressure increase process, the mold clamping process, the depressurization process, and the mold opening process shown in FIG. 4. The ejector control unit 712 controls the ejector 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, the injection motor 350, but may 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 device 300 and performs the metering process. The metering drive source is, for example, the metering motor 340, but may 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 inside 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 by a speed detector. The speed detector is, for example, an injection motor encoder 351. In the filling step, the pressure acting on the molding material from the injection member (hereinafter also referred to as "filling pressure") increases as the injection member advances. 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 replenishing the molding material that is insufficient due to cooling contraction in the mold device 800 by pushing the injection member forward. 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 setting unit 713a and a command creation unit 713b. The speed setting unit 713a creates a set value for the speed of the injection member based on the deviation between the set value and the actual value of the filling pressure. The command creation unit 713b creates a command (for example, a current command) for the injection drive source based on the deviation between the set value and the actual value of the speed of the injection member. The injection drive source is, for example, the injection motor 350. The injection drive source is driven in accordance with the command created by the command creation unit 713b.

[0108] The speed setting unit 713a creates a set value for the speed of the injection member so that the actual value of the filling pressure becomes the set value. The actual value of the filling pressure is acquired using a pressure detector such as the load detector 360. The speed setting unit 713a creates the set value for the speed of the injection member by, for example, PID calculation or PI calculation.

[0109] The command creation unit 713b creates a command for the injection drive source so that the actual value of the speed of the injection member becomes the set value. The actual value of the speed of the injection member is acquired using a speed detector such as the injection motor encoder 351. The command creation unit 713b creates a command for the injection drive source by, for example, PID calculation or PI calculation.

[0110] The injection control unit 713 has a limiting unit 713c. The limiting unit 713c limits the retraction speed of the injection member to a preset limit value V1 or less during the retraction of the injection member in the pressure holding process. This can eliminate adverse effects on the quality of the molded product caused by the injection member retracting at high speed in the pressure holding process. The limit value V1 is set so as to eliminate adverse effects on the quality of the molded product caused by the injection member retracting at high speed.

[0111] For example, the limiting unit 713c compares the retraction speed setting value (>0) created by the speed setting unit 713a with the limiting value V1 (V1>0) as shown in Fig. 6. The limiting unit 713c outputs the minimum value (including the case where the setting value and the limiting value V1 are equal) of the retraction speed setting value (>0) created by the speed setting unit 713a and the limiting value V1 (V1>0) as the retraction speed setting value to the command creating unit 713b. The command creating unit 713b creates a command for the injection drive source based on the deviation between the setting value output by the limiting unit 713c and the actual value.

[0112] 6, the limiting unit 713c has a correcting unit 713d that monitors the position of the injection member during the retraction of the injection member in the pressure holding process, corrects the set value of the retraction speed according to the position of the injection member, and outputs the corrected set value to the command creating unit 713b. The correcting unit 713d obtains the position of the injection member using a position detector such as the injection motor encoder 351.

[0113] During the pressure holding process, when the position of the injection member reaches a preset deceleration start position A2 (see FIG. 7) during the retraction of the injection member, the correction unit 713d corrects the set value of the retraction speed of the injection member to a speed smaller than the limit value V1. The deceleration start position A2 is set behind the filling start position A3 and ahead of the retraction limit position A0. The filling start position A3 is the position at the start of the filling process.

[0114] As a result, in the pressure holding process, when the injection member reaches the deceleration start position A2 during the retraction of the injection member, the retraction speed of the injection member becomes smaller than the limit value V1. Therefore, even if the injection member is retracted to the retract limit position A0, the retraction speed at that time is small and the impact is small. Therefore, the impact can be reduced. Furthermore, until the injection member reaches the deceleration start position A2, the retraction speed can be controlled to the limit value V1, and the filling pressure can be quickly reduced.

[0115] The correction unit 713d corrects the set value of the retraction speed of the injection member to zero when the position of the injection member reaches a preset stop position A1 during retraction of the injection member in the pressure holding process. The stop position A1 is set behind the deceleration start position A2 and ahead of the retraction limit position A0. Thereby, when the position of the injection member reaches the stop position A1 during retraction of the injection member in the pressure holding process, the injection member is stopped. Therefore, it is possible to prevent the position of the injection member from being retracted to the retraction limit position A0, and it is possible to eliminate the impact caused by the position of the injection member being retracted to the retraction limit position A0.

[0116] The correction unit 713d corrects the retraction speed of the ejection member to a gradually slower speed as the position of the ejection member approaches the stop position A1 from the deceleration start position A2. This causes the retraction speed of the ejection member to gradually slower as the position of the ejection member approaches the stop position A1 from the deceleration start position A2. The retraction speed can be gradually reduced, and the occurrence of vibration can be suppressed.

[0117] Next, an example of the change over time of the screw speed, filling pressure, and screw position will be described with reference to Fig. 7. In Fig. 7, the screw speed is an example of the speed of the injection member, and the screw position is an example of the position of the injection member. The screw position is represented by the distance from the forward limit position of the movable range of the screw 330. The further the screw position retreats from the forward limit position, the greater the distance representing the screw position.

[0118] In Figure 7, t0 represents the start time of the filling process, t1 represents the time of V / P switching, t2 represents the time when the actual screw speed (retraction speed) reaches the limit value V1, t3 represents the time when the screw position reaches the deceleration start position A2, t4 represents the time when the screw position reaches the stop position A1, and t5 represents the end time of the pressure holding process.

[0119] When the filling process starts at time t0, the screw position advances at a set speed. As a result, the filling pressure rises. If the nozzle is clogged or the molded product is not easily removed, the filling pressure will rise rapidly because almost no molding material is injected even if the screw position advances.

[0120] After that, when the screw position reaches the V / P switching position at time t1, the pressure dwell process starts. In the pressure dwell process, the screw position is controlled so that the actual value of the filling pressure becomes the set value P1. When nozzle clogging occurs, the actual value of the filling pressure is larger than the set value P1 and the deviation is large.

[0121] Therefore, when nozzle clogging occurs, the screw position is retreated so that the actual filling pressure value becomes smaller after time t1. Then, the screw speed (specifically, the retreat speed) gradually increases, and at time t2, the retreat speed reaches the limit value V1.

[0122] The limiting unit 713c limits the retreat speed to the limiting value V1 so that the retreat speed does not exceed the limiting value V1. After that, when the screw position reaches the deceleration start position A2 at time t3, the limiting unit 713c controls the retreat speed to a speed smaller than the limiting value V1. As a result, even if the screw position is retreated to the retreat limit position A0, the retreat speed at that time is small and the impact is small. Therefore, the impact can be reduced. Furthermore, until the screw position reaches the deceleration start position A2, the retreat speed can be controlled to the limiting value V1, and the filling pressure can be quickly reduced.

[0123] After that, when the screw position reaches the stop position A1 at time t4, the limiting section 713c stops the screw 330. The stop position A1 is set forward of the retraction limit position A0. Therefore, it is possible to prevent the screw position from being retracted to the retraction limit position A0, and it is possible to eliminate the impact caused by the screw position being retracted to the retraction limit position A0.

[0124] 7, between time t3 and time t4, as the screw position approaches the stop position A1 from the deceleration start position A2, the limiting section 713c controls the retraction speed to a gradually slower speed. The retraction speed can be gradually decelerated, and the occurrence of vibration can be suppressed.

[0125] Although the embodiments of the control device for an injection molding machine, the injection molding machine, and the control method for an injection molding machine according to the present invention have been described above, the present invention is not limited to the above-mentioned embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. Naturally, these also fall within the technical scope of the present invention. [Explanation of symbols]

[0126] 10 injection molding machine 310 Cylinder 330 Screw (injection member) 350 Injection motor (injection drive source) 700 Control device 713c Restrictions 800 Mold Equipment

Claims

1. A control device for an injection molding machine including an injection member provided inside a cylinder that heats a molding material, and an injection drive source that fills the molding material into a mold device by moving the injection member forward, a limiting unit that limits a retreat speed of the injection member to a preset limit value or less in a pressure holding step of controlling a filling pressure applied to the molding material from the injection member, The limiting unit controls the retraction speed of the injection member to a speed lower than the limit value when the position of the injection member reaches a predetermined deceleration start position during the pressure holding process.

2. the limiting section stops the injection member at a preset stop position when the injection member reaches the preset stop position during the retraction of the injection member in the pressure holding step, 2. The control device for an injection molding machine according to claim 1, wherein the stop position is set behind the deceleration start position and ahead of a rearward limit position of a movable range of the injection member.

3. The control device for an injection molding machine according to claim 2 , wherein the limiting section controls the retraction speed of the injection member to gradually decrease as the position of the injection member approaches the stop position from the deceleration start position.

4. a speed setting unit that creates a set value of the speed of the injection member based on a deviation between an actual value and a set value of the filling pressure, and a command creating unit that creates a command for the injection drive source based on the deviation between the actual value and the set value of the speed, 4. The control device for an injection molding machine according to claim 1, wherein the limiting unit outputs a minimum value of the set value of the retreat speed created by the speed setting unit and the limiting value as the set value of the retreat speed to the command creating unit during the retreat of the injection member in the pressure holding process.

5. 5. An injection molding machine comprising: the control device according to claim 1; the injection member; and the injection drive source.

6. A control method for an injection molding machine including an injection member provided inside a cylinder that heats a molding material, and an injection drive source that fills the molding material into a mold device by moving the injection member forward, comprising: a step of limiting a retreat speed of the injection member to a preset limit value or less in a pressure holding step of controlling the injection drive source so that an actual value of a filling pressure acting on the molding material from the injection member becomes a set value; a step of decelerating the retraction speed of the injection member to a speed lower than the limit value when a position of the injection member reaches a preset deceleration start position during the retraction of the injection member in the pressure holding step; A method for controlling an injection molding machine comprising the steps of:

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