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

Abstract

To provide a technology for easily and appropriately adjusting cold start prevention time.SOLUTION: A control device for an injection molding machine includes an injection member that injects molding material from a cylinder into a mold device, and a drive source that operates the injection member. The control device has a cold start prevention part that performs control to limit an operation of the injection member for a preset cold start prevention time when a first condition is satisfied. In order to determine whether or not a value shorter than an initial value should be used as the cold start prevention time, the cold start prevention part determines whether or not a second condition different from the first condition is satisfied, even when the first condition is satisfied.SELECTED DRAWING: Figure 5

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 an injection member that injects molding material from a cylinder into a mold device, and a drive source that operates the injection member. The injection member is provided inside the cylinder. The injection member is, for example, a screw. The molding material is, for example, a resin. The molding material is melted inside the cylinder and then injected from the cylinder into the mold device.

[0003] The injection molding machine includes a heater for heating the cylinder and a temperature detector for detecting the actual temperature of the cylinder. The injection molding machine controls the heater so that the actual temperature of the cylinder becomes a set temperature. The set temperature of the cylinder is prepared for each operation mode of the injection molding machine.

[0004] The operation modes of the injection molding machine include, for example, a molding mode and a heat retention mode. In the molding mode, the molding material is injected from the cylinder into the mold device. In the heat retention mode, the operation of the injection member is stopped at night or on holidays. In the heat retention mode, the cylinder temperature is set lower than in the molding mode to suppress carbonization of the molding material.

[0005] The operation modes of the injection molding machine may further include a purge mode. In the purge mode, for example, after the warming mode and before the molding mode, the molding material in the cylinder is replaced by injecting the molding material from the cylinder to the outside of the mold device. In the purge mode, the temperature of the cylinder is set lower than that in the molding mode.

[0006] The control device of the injection molding machine may increase the temperature of the cylinder, for example, when the set temperature for the molding mode is changed to a higher temperature during the molding mode, when the operation mode of the injection molding machine is switched from the warm-keeping mode or the purge mode to the molding mode, or when the power supply to the heater is cut off due to a power outage or an operating error and then resumed.

[0007] If the temperature rise of the cylinder is large, a time lag occurs between the completion of the temperature rise of the cylinder and the completion of the temperature rise of the molding material in the cylinder. If the drive source operates the injection member before the molding material in the cylinder is sufficiently heated, an excessive load is applied to the injection member, which may cause damage to the injection member. In addition, molding defects may occur.

[0008] Therefore, the control device of the injection molding machine performs control to limit the operation of the injection member until the molding material in the cylinder is sufficiently heated. The control to limit the operation of the injection member is called cold start prevention. The time during which the cold start prevention is performed is called the cold start prevention time. The cold start prevention time is set in advance through experiments or the like so that the molding material in the cylinder is sufficiently heated.

[0009] However, if the temperature rise in the cylinder is small, the molding material in the cylinder has already been sufficiently heated. Even in this case, if the operation of the injection member is restricted for the initially set cold start prevention time, it will take unnecessary time to resume production of molded products.

[0010] Patent Document 1 discloses a technique that enables the operation of an injection member based on the type of resin and the stoppage time, as long as the stoppage time from when the injection molding machine is stopped until it is restarted is within a certain period of time. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Publication No. 11-170327 Summary of the Invention [Problem to be solved by the invention]

[0012] As in Patent Document 1, control according to the type of resin requires the preparation of a complex calculation program tailored to the resin characteristics, and special electrical components are required to execute the calculation program. Furthermore, the input of information on the resin characteristics is required before the injection molding machine operates, which increases the burden on the operator. The burden on the operator increases especially when the type of resin is changed frequently.

[0013] One aspect of the present invention provides a technique for easily and appropriately adjusting the cold start prevention time. [Means for solving the problem]

[0014] A control device according to one aspect of the present invention is a control device for an injection molding machine including an injection member that injects molding material from a cylinder into a mold device and a drive source that operates the injection member. The control device has a cold start prevention unit that performs control to limit the operation of the injection member for a preset cold start prevention time when a first condition is satisfied. The cold start prevention unit determines whether a second condition different from the first condition is satisfied even when the first condition is satisfied, in order to determine whether a value shorter than an initial value should be used as the cold start prevention time. Effect of the Invention

[0015] According to one aspect of the present invention, the cold start prevention time can be adjusted simply and appropriately. [Brief description of the drawings]

[0016] [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 flowchart showing an example of the process of the cold start prevention unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] 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.

[0018] (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.

[0019] 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.

[0020] (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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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. Moreover, the clamping force may be set instead of the position of the crosshead (e.g., the clamping position) or the position of the movable platen.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] (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.

[0056] 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).

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] (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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] (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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] (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.

[0098] 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."

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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).

[0106] (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.

[0107] As shown in Fig. 3, the control device 700 has, for example, a mold clamping control unit 711, an ejector control unit 712, an injection control unit 713, a measurement control unit 714, a temperature control unit 715, and a cold start prevention unit 716. The mold clamping control unit 711 controls the mold clamping device 100 and performs the mold closing process, pressure increase process, mold clamping process, depressurization process, and mold opening process shown in Fig. 4. The ejector control unit 712 controls the ejector device 200 and performs the ejection process.

[0108] The injection control unit 713 controls the injection drive source of the injection device 300 to carry out the injection process. The injection drive source is an injection motor 350 in this embodiment, but may be a hydraulic cylinder or the like. The injection process is carried out during the mold clamping process as shown in FIG. 4. The injection control unit 713 controls the operation of the injection member. The injection member is provided inside the cylinder 310, and injects the molding material from the cylinder 310 into the mold device 800. The injection member is a screw 330 in this embodiment, but may be a plunger.

[0109] The injection control unit 713 monitors the actual value of the moving speed of the screw 330. The moving speed of the screw 330 is detected by using a speed detector. The speed detector is, for example, the injection motor encoder 351. The injection control unit 713 also monitors the actual value of the pressure acting on the molding material from the screw 330. The pressure is detected by 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. The injection process includes a filling process and a pressure holding process in this order as shown in FIG. 4.

[0110] The filling process is a process in which the screw 330 is moved forward to fill the interior of the mold device 800 with the liquid molding material accumulated in front of the screw 330. The filling process is, for example, a process in which the injection motor 350 is controlled so that the actual value of the moving speed of the screw 330 provided inside the cylinder 310 becomes a set value. In the filling process, the screw 330 moves forward, and thus the actual value of the pressure acting on the molding material from the screw 330 increases.

[0111] The pressure holding process is a process for replenishing the molding material that is insufficient due to cooling contraction in the mold device 800 by pushing the screw 330 forward. The pressure holding process is, for example, a process for controlling the injection motor 350 so that the actual value of the pressure acting on the molding material from the screw 330 becomes a set value.

[0112] The metering control unit 714 controls the metering drive source of the injection unit 300 to carry out the metering process. The metering drive source is the metering motor 340 in this embodiment, but may be a hydraulic pump or the like. The metering process is preferably carried out during the cooling process as shown in FIG. 4 in order to shorten the molding cycle time. The cooling process is started after the completion of the pressure holding process. In the cooling process, the molding material in the cavity space 801 is solidified.

[0113] The temperature control unit 715 controls the temperature of the cylinder 310. The cylinder 310 is divided into a plurality of zones in the axial direction of the cylinder 310 (for example, the X-axis direction). A first heater 313 and a first temperature detector 314 are provided in each of the plurality of zones. The first heater 313 heats the cylinder 310. The first temperature detector 314 detects the actual temperature of the cylinder 310. A set temperature is set for each of the plurality of zones.

[0114] The temperature control unit 715 detects the actual temperature of each of the multiple zones with the first temperature detector 314, and individually feedback controls the output of the first heater 313 for each zone so that the actual temperature detected by the first temperature detector 314 becomes the set temperature. The multiple first heaters 313 may have the same configuration or different configurations. The first heaters 313 are, for example, band heaters. The output of the first heater 313 is expressed, for example, as a percentage (%) of power-on time per unit time. The larger the percentage of power-on time, the higher the output of the first heater 313.

[0115] Although not shown, when multiple first heaters 313 are provided in one zone, the proportions of the energizing times of the multiple first heaters 313 are controlled to be the same. Although not shown, multiple first temperature detectors 314 may be provided in one zone. The number of zones, the number of first heaters 313, and the number of first temperature detectors 314 do not have to match.

[0116] The set temperature of the cylinder 310 is prepared for each operation mode of the injection molding machine 10. The operation modes of the injection molding machine 10 include, for example, a molding mode and a heat retention mode. In the molding mode, the molding material is injected from the cylinder 310 into the mold device 800. In the heat retention mode, the operation of the screw 330 is stopped at night, on holidays, etc. In the heat retention mode, the temperature of the cylinder 310 is set lower than that in the molding mode to suppress carbonization of the molding material.

[0117] The operation modes of the injection molding machine 10 may further include a purge mode. In the purge mode, for example, after the warming mode and before the molding mode, the molding material in the cylinder 310 is replaced by injecting the molding material from the cylinder 310 to the outside of the mold device 800. In the purge mode, the temperature of the cylinder 310 is set lower than that in the molding mode.

[0118] The temperature control unit 715 may increase the temperature of the cylinder 310. The temperature of the cylinder 310 is increased, for example, when the set temperature for the molding mode is changed to a higher temperature during the molding mode, when the operation mode of the injection molding machine 10 is switched from the warm-keeping mode or the purge mode to the molding mode, or when the power supply to the heater is cut off due to a power outage or an operating error and then resumed.

[0119] If the temperature rise of the cylinder 310 is large, a time lag occurs between the completion of the temperature rise of the cylinder 310 and the completion of the temperature rise of the molding material in the cylinder 310. If the metering motor 340 or the injection motor 350 operates the screw 330 before the molding material in the cylinder 310 is sufficiently heated, an excessive load acts on the screw 330, which may damage the screw 330. In addition, molding defects may occur.

[0120] Therefore, the cold start prevention unit 716 performs control to limit the operation of the screw 330 until the molding material in the cylinder 310 is sufficiently heated. The control to limit the operation of the screw 330 is called cold start prevention. Also, the time during which the cold start prevention is performed is called cold start prevention time.

[0121] An initial value t0 of the cold start prevention time t is set based on the configuration of the injection unit 300 and the type of molding material, and is stored in advance in the storage medium 702. The initial value t0 is not particularly limited, but is, for example, 15 minutes. The initial value t0 may be input by a user, or may be automatically set by the control unit 700 by acquiring information on the type of molding material.

[0122] The start point of the cold start prevention time t is not limited to the time when the temperature rise of the cylinder 310 is completed, that is, when the actual temperature of the cylinder 310 reaches the set temperature. The start point of the cold start prevention time t can be set arbitrarily. For example, the start point of the cold start prevention time t may be when the actual temperature of the cylinder 310 reaches a temperature that is shifted by a predetermined amount from the set temperature to the lower temperature side.

[0123] Incidentally, if the temperature rise width of the cylinder 310 is small, the molding material inside the cylinder 310 has been sufficiently heated. Even in such a case, if the initial value t0 is used as the cold start prevention time, it will take unnecessary time before production of molded products can be resumed.

[0124] The cold start prevention unit 716, which will be described in detail later, uses an initial value t0 as the cold start prevention time t when the first condition is satisfied, and performs control to limit the operation of the screw 330 during the initial value t0. However, in order to determine whether a value shorter than the initial value t0 should be used as the cold start prevention time t, the cold start prevention unit 716 determines whether a second condition different from the first condition is satisfied even when the first condition is satisfied. By taking into account not only the first condition but also the second condition, the cold start prevention time t can be easily and appropriately adjusted.

[0125] Even if the first condition is satisfied, when the second condition is satisfied, the cold start prevention unit 716 uses a value shorter than the initial value t0 as the cold start prevention time, or notifies the user that a value shorter than the initial value t0 should be used as the cold start prevention time. The notification includes displaying on a screen or outputting by voice. After performing the notification, when the cold start prevention unit 716 detects that a predetermined operation has been performed by the user, the cold start prevention unit 716 uses a value shorter than the initial value t0 as the cold start prevention time. Note that using a value shorter than the initial value t0 as the cold start prevention time t includes setting the cold start prevention time t to zero, that is, not implementing cold start prevention.

[0126] Next, an example of the processing of the cold start prevention unit 716 will be described with reference to Fig. 5. The processing from step S101 shown in Fig. 5 is repeated at predetermined time intervals during startup of the injection molding machine 10, for example. First, the cold start prevention unit 716 determines whether the set temperature Tref of the cylinder 310 has been changed (step S101). The zone to be determined is preferably the frontmost zone of the cylinder 310 (the zone closest to the nozzle 320).

[0127] The molding material is injected from inside the cylinder 310 through the nozzle 320 into the mold device 800. If the metering motor 340 or the injection motor 350 operates the screw 330 in a state in which the molding material is not sufficiently melted in the frontmost zone of the cylinder 310, an excessive load acts on the screw 330, which may damage the screw 330. In addition, molding defects may occur.

[0128] In the processing of the cold start prevention unit 716, the set temperature Tref of the cylinder 310 is preferably the set temperature Tref of the frontmost zone of the cylinder 310. Also, in the processing of the cold start prevention unit 716, the actual temperature Tdet of the cylinder 310 is preferably the actual temperature Tdet of the frontmost zone of the cylinder 310.

[0129] When the set temperature Tref of the cylinder 310 is changed (step S101, YES), the cold start prevention unit 716 determines whether the cylinder 310 was in a state where the temperature rise of the cylinder 310 was completed immediately before the change of the set temperature Tref (step S102). The state where the temperature rise of the cylinder 310 is completed is a state where the actual temperature Tdet of the cylinder 310 has reached the set temperature Tref.

[0130] In steps S101 and S102, the first condition is that the set temperature Tref of the cylinder 310 has been changed. The second condition is that the state of the cylinder 310 has completed heating immediately before the first condition is satisfied. An example of a case in which the first condition is satisfied and the second condition is a case in which the set temperature Tref for the molding mode is changed during the molding mode.

[0131] The set temperature Tref to be changed is not limited to that for the molding mode, and may be that for the purge mode. In other words, when the first condition is satisfied and the second condition is satisfied, the set temperature Tref for the purge mode may be changed during the purge mode. Note that the warm-keeping mode is not subject to cold start prevention because it stops the operation of the screw 330.

[0132] If the first condition is satisfied in steps S101 and S102 but the second condition is not satisfied (step S102, NO), the temperature rise of the cylinder 310 has not been completed since before the first condition was satisfied. Therefore, the molding material in the cylinder 310 has not been heated sufficiently. Therefore, the cold start prevention unit 716 sets the cold start prevention time t to an initial value t0 (step S103), and then performs the process from step S109 onwards. The process from step S109 onwards will be described later.

[0133] On the other hand, when the first condition is satisfied in steps S101 and S102 and the second condition is satisfied (step S102, YES), if the difference ΔT (ΔT=Tref-Tdet) between the set temperature Tref and the actual temperature Tdet of the cylinder 310 is small at the time when the first condition is satisfied, the molding material in the cylinder 310 has been sufficiently heated. Therefore, the cold start prevention unit 716 performs the process from step S107 onwards. The process from step S107 onwards will be described later.

[0134] When the set temperature Tref of the cylinder 310 has not been changed (step S101, NO), the cold start prevention unit 716 judges whether the cylinder 310 has started to heat up (step S104). Examples of the state in which the cylinder 310 has started to heat up include a state in which the operation mode of the injection molding machine 10 is switched from the warm-keeping mode or the purge mode to the molding mode, and a state in which the power supply is interrupted due to a power outage or an operating error and then resumed.

[0135] The injection molding machine 10 has two operation modes: a molding mode and a warm-keeping mode. In the molding mode, a set temperature Tref for the molding cycle is used. In the warm-keeping mode, a set temperature Tref for warm-keeping is used. The injection molding machine 10 may further have a purge mode as an operation mode. In the purge mode, a set temperature Tref for purge is used.

[0136] If the cylinder 310 has not started to heat up (step S104, NO), the set temperature Tref of the cylinder 310 has not been changed, and the operation of the injection molding machine 10 has not been interrupted, and the molding material in the cylinder 310 has been sufficiently heated. Therefore, in this case, the cold start prevention unit 716 ends the current process without performing step S109.

[0137] If the cylinder 310 has started to heat up (step S104, YES), the cold start prevention unit 716 determines whether the cylinder 310 completed heating a set time before (e.g., 15 minutes before) from the start of heating up of the cylinder 310 (step S105). The set time is 15 minutes, which is the same as the initial value t0 in FIG. 5, but can be set arbitrarily.

[0138] In steps S104 and S105, the first condition is that the cylinder 310 has started to heat up. The second condition is that the cylinder 310 has completed heating up before a set time from when the first condition is satisfied. Examples of cases where the first condition is satisfied and the second condition is satisfied include a case where the power outage is short and operation is immediately resumed, and a case where operation is immediately resumed due to a user's operational error.

[0139] If the first condition is satisfied but the second condition is not satisfied in steps S104 and S105 (step S105, NO), the temperature rise of the cylinder 310 has not been completed since before the first condition was satisfied. Therefore, the molding material in the cylinder 310 has not been heated sufficiently. Therefore, the cold start prevention unit 716 sets the cold start prevention time t to an initial value t0 (step S106), and then performs the process from step S109 onwards. The process from step S109 onwards will be described later.

[0140] On the other hand, when the first condition is satisfied in steps S104 and S105 and the second condition is satisfied (step S105, YES), if the difference ΔT (ΔT=Tref-Tdet) between the set temperature Tref and the actual temperature Tdet of the cylinder 310 is small at the time when the first condition is satisfied, the molding material in the cylinder 310 has been sufficiently heated. Therefore, the cold start prevention unit 716 performs the process from step S107 onwards. The process from step S107 onwards will be described later.

[0141] In step S107, the cold start prevention unit 716 acquires the set temperature Tref and the actual temperature Tdet of the cylinder 310 at the time when the first condition is satisfied. Tref and Tdet are associated with the time and stored in the storage medium 702, and the stored data is read out and used.

[0142] Next, the cold start prevention unit 716 determines whether to use a value shorter than the initial value t0 as the cold start prevention time t based on the set temperature Tref and the actual temperature Tdet of the cylinder 310 at the time when the first condition is satisfied. The cold start prevention unit 716 sets a value shorter than the initial value t0 as the cold start prevention time t based on ΔT (ΔT=Tref-Tdet) at the time when the first condition is satisfied (step S108).

[0143] The smaller ΔT at the time when the first condition is satisfied, the less the heating of the molding material in the cylinder 310 is. Therefore, the smaller ΔT at the time when the first condition is satisfied, the shorter the cold start prevention time t may be set. The cold start prevention time t may be set in stages according to ΔT. The cold start prevention time t may also be set to zero. Note that if ΔT at the time when the first condition is satisfied is too large, the molding material in the cylinder 310 is not sufficiently heated, so the cold start prevention time t may be set to an initial value t0.

[0144] In this embodiment, the cold start prevention unit 716 sets the cold start prevention time t to a value shorter than the initial value t0 based on ΔT at the time when the first condition is satisfied, but the cold start prevention time t may be set to a value shorter than the initial value t0 based on a parameter other than ΔT. Instead of ΔT, for example, the ratio between Tref and Tdet may be used.

[0145] When the first condition is that the set temperature Tref of the cylinder 310 has been changed or that the cylinder 310 has started to heat up, the second condition may be that the temperature rise of the cylinder 310 is completed before a set time (e.g., 15 minutes) has elapsed since the first condition was satisfied. When this second condition is satisfied, it is also considered that the molding material in the cylinder 310 has been sufficiently heated. The cold start prevention unit 716 may determine whether or not to use a value shorter than the initial value t0 as the cold start prevention time, based on the time from the time the first condition is satisfied until the temperature rise of the cylinder 310 is completed.

[0146] In step S109, the cold start prevention unit 716 performs cold start prevention for a preset period of time t. After that, the cold start prevention unit 716 ends the current process.

[0147] In this embodiment, the actual temperature of the cylinder 310 is used as the starting point of the cold start prevention time t, but it is also possible to use the actual temperature of the mold assembly 800. The mold assembly 800 may be equipped with a hot runner (not shown). The hot runner includes a heater for heating the flow path of the molding material, and a temperature detector for detecting the actual temperature of the flow path of the molding material. The temperature control unit 715 controls the heater so that the actual temperature of the flow path of the molding material becomes the set temperature.

[0148] The temperature control unit 715 may heat up the mold device 800 before resuming the molding cycle. There is a time lag between when the temperature detector of the mold device 800 detects the completion of the temperature rise of the mold device 800 and when the temperature rise of the entire flow path of the molding material is completed. If the metering motor 340 or the injection motor 350 operates the screw 330 when the mold device 800 is not sufficiently heated, the mold device 800 may be damaged or molding defects may occur. Therefore, the cold start prevention unit 716 may perform control to limit the operation of the screw 330 until the mold device 800 is sufficiently heated.

[0149] 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]

[0150] 10 injection molding machine 310 Cylinder 330 Screw (injection member) 340 Metering motor (drive source) 350 Injection motor (drive source) 700 Control device 716 Cold start prevention part 800 Mold Equipment

Claims

1. A control device for an injection molding machine including an injection member that injects a molding material from a cylinder into a mold device, and a drive source that operates the injection member, a cold start prevention unit that performs control to limit the operation of the injection member for a preset cold start prevention time when a first condition is satisfied, The cold start prevention unit determines whether a second condition different from the first condition is satisfied even when the first condition is satisfied, in order to determine whether a value shorter than an initial value should be used as the cold start prevention time.

2. 2. The control device for an injection molding machine according to claim 1, wherein the cold start prevention unit uses a value shorter than an initial value as the cold start prevention time or notifies a user that a value shorter than the initial value should be used as the cold start prevention time when the second condition is satisfied, even when the first condition is satisfied.

3. the first condition includes that a set temperature of the cylinder or the die device has been changed, 3. The control device for an injection molding machine according to claim 1 or 2, wherein the second condition includes that the cylinder or the mold device has completed heating up just before the first condition is satisfied, or that the cylinder or the mold device has completed heating up before a set time has elapsed since the first condition is satisfied.

4. The first condition includes a state in which the cylinder or the die device has started to heat up, 3. The control device for an injection molding machine according to claim 1 or 2, wherein the second condition includes that the cylinder or the mold device has completed heating before a set time has elapsed since the first condition is satisfied, or that the cylinder or the mold device has completed heating before a set time has elapsed since the first condition is satisfied.

5. 3. The control device for an injection molding machine according to claim 1, wherein the cold start prevention unit determines whether or not a value shorter than an initial value should be used as the cold start prevention time based on a set temperature and an actual temperature of the cylinder or the mold device at the time when the first condition is satisfied.

6. 3. The control device for an injection molding machine according to claim 1, wherein the cold start prevention unit determines whether or not to use a value shorter than an initial value as the cold start prevention time based on the time from when the first condition is satisfied to when the temperature of the cylinder or the mold device is completed.

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

8. A control method for an injection molding machine having a drive source that operates an injection member that injects molding material from a cylinder into a mold device, comprising: When a first condition is satisfied, control is performed to limit the operation of the injection member for a preset cold start prevention time, a control method for an injection molding machine, the control method comprising: determining whether a second condition different from the first condition is satisfied even when the first condition is satisfied, in order to determine whether a value shorter than an initial value should be used as the cold start prevention time.

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