WO2020045359A1

WO2020045359A1 - Injection molding machine

Info

Publication number: WO2020045359A1
Application number: PCT/JP2019/033351
Authority: WO
Inventors: 大吾堀田; 大石　潔; 勇希横倉; 佑樹松井
Original assignee: 住友重機械工業株式会社
Priority date: 2018-08-27
Filing date: 2019-08-26
Publication date: 2020-03-05
Also published as: CN112638616A; JP2020032544A; JP7175674B2; CN116787722A

Abstract

The objective of the present invention is to provide an injection molding machine with which the time until an axial force balance is stabilized can be reduced. This injection molding machine comprises a mold clamping device including a plurality of tie bars, and a tie bar axial force adjusting device for adjusting the axial forces of the tie bars, wherein: the tie bar axial force adjusting device includes axial force detectors for detecting the axial forces of the tie bars, and an axial force control unit for controlling the temperatures of the tie bars on the basis of a deviation between the detected value and a set value of the axial force of each tie bar; the axial force detectors are provided on the plurality of tie bars; the axial force control unit includes an axial force control command generating unit for generating control commands for increasing the temperature of each tie bar if the detected value of the axial force of the tie bar is higher than the set value; and if the detected value of the axial force of each tie bar is lower than the set value, the axial force control command generating unit performs a deviation reduction process to reduce the deviation between the detected value and the set value, to reduce an amount of decrease in the temperature of the tie bar.

Description

Injection molding machine

The present invention relates to an injection molding machine.

The injection molding machine has a mold clamping device that closes, clamps, and opens the mold device. The mold clamping device has a plurality of tie bars that extend according to the mold clamping force. The mold clamping force is applied to a plurality of tie bars and the tie bars are extended. The force that resists the extension of the tie bar is called the axial force.

For example, in multi-cavity molding, if the balance of the pressing force of the mold is not good, the thickness of each molded product may be different. In order to solve this, it has been studied to control the temperature of the tie bar to improve the balance of the pressing force of the mold. Specifically, the temperature of a tie bar is raised / lowered by a heater / cooler (for example, see Patent Document 1).

Here, switching between heating and cooling causes discontinuous control and poor controllability. Therefore, it is preferable to change the tie bar temperature only by turning on / off the heater without using a cooler.

JP 2008-114513 A

However, in the method of stopping the heater and lowering the temperature of the tie bar (natural cooling), it takes time to lower the temperature to a predetermined temperature. For this reason, there is a problem of a decrease in yield and a prolonged startup.

The present invention has been made in view of the above problems, and has as its main object to provide an injection molding machine capable of shortening the time required for stabilizing the balance of axial force.

In order to solve the above problems, according to one embodiment of the present invention,
A mold clamping device having a plurality of tie bars,
A tie bar axial force adjusting device for adjusting the axial force of the tie bar, and an injection molding machine,
The tie bar axial force adjusting device,
An axial force detector for detecting an axial force of the tie bar;
An axial force control unit that controls the temperature of the tie bar based on a deviation between a detected value and a set value of the axial force of the tie bar,
The axial force detector is provided on the plurality of tie bars,
The axial force control unit, when the detected value of the axial force of the tie bar is higher than a set value, has an axial force control command generation unit that generates a control command to increase the temperature of the tie bar,
When the detected value of the axial force of the tie bar is lower than a set value, the axial force control command generation unit performs a deviation reduction process to reduce a deviation between the detected value and the set value, and the amount of decrease in the temperature of the tie bar. , An injection molding machine is provided.

According to one aspect of the present invention, there is provided an injection molding machine capable of shortening the time until the balance of the axial force is stabilized.

It is a figure showing the state at the time of the mold opening completion of the injection molding machine by one embodiment. It is a figure showing the state at the time of mold closure of the injection molding machine by one embodiment. FIG. 4 is a diagram illustrating a positional relationship of a tie bar of the injection molding machine according to one embodiment, and is a diagram when a fixed platen is viewed from a movable platen side. It is a block diagram showing an example of axial force control of an injection molding machine concerning one embodiment. It is a block diagram showing other examples of axial force control of the injection molding machine concerning one embodiment. It is a block diagram showing yet another example of axial force control of an injection molding machine concerning one embodiment. 4 is a graph showing an example of the temperature of each tie bar and the mold clamping force in the axial force control of the injection molding machine according to one embodiment.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same or corresponding reference numerals, and description thereof is omitted.

FIG. 1 is a diagram showing a state of the injection molding machine according to one embodiment at the time of completion of mold opening. FIG. 2 is a diagram showing a state of the injection molding machine according to one embodiment at the time of mold clamping. The injection molding machine includes a frame Fr, a mold clamping device 10, an operation device 70, a display device 80, a controller 90, and the like.

The controller 90 has a CPU (Central Pocessing Unit) 91 and a storage medium 92 such as a memory. The controller 90 controls the mold clamping device 10, the operating device 70, the display device 80, and the like by causing the CPU 91 to execute the program stored in the storage medium 92.

The controller 90 is connected to the operation device 70 and the display device 80. The operation device 70 accepts an input operation by the user and outputs a signal corresponding to the input operation to the controller 90. The display device 80 displays a display screen according to an input operation on the operation device 70 under the control of the controller 90.

The display screen is used for setting the injection molding machine. A plurality of display screens are prepared and displayed by switching or overlapping. The user operates the operation device 70 while looking at the display screen displayed on the display device 80 to set the injection molding machine (including input of set values) and the like.

The operation device 70 and the display device 80 may be configured by, for example, a touch panel and may be integrated. Although the operation device 70 and the display device 80 of the present embodiment are integrated, they may be provided independently. Further, a plurality of operation devices 70 may be provided.

The mold clamping device 10 performs mold closing, pressurization, mold clamping, depressurization, and mold opening of the mold device 30. The mold clamping device 10 includes a fixed platen 12, a movable platen 13, a toggle support 15, a tie bar 16, a toggle mechanism 20, and a mold clamping motor 21. Hereinafter, the moving direction of the movable platen 13 when the mold is closed (the right direction in FIGS. 1 and 2) is referred to as forward, and the moving direction of the movable platen 13 when the mold is opened (the left direction in FIGS. 1 and 2) is referred to as the rear. I do.

The fixed platen 12 is fixed to the frame Fr. A fixed mold 32 is attached to a surface of the fixed platen 12 facing the movable platen 13.

The movable platen 13 is movable along a guide (for example, a guide rail) 17 laid on the frame Fr, and is movable forward and backward with respect to the fixed platen 12. A movable mold 33 is attached to a surface of the movable platen 13 facing the fixed platen 12.

型 By moving the movable platen 13 with respect to the fixed platen 12, the mold is closed, the mold is closed, and the mold is opened. The mold device 30 is composed of the fixed mold 32 and the movable mold 33.

The toggle support 15 is connected to the fixed platen 12 at an interval, and is movably mounted on the frame Fr in the mold opening and closing direction. The toggle support 15 may be movable along a guide laid on the frame Fr. The guide of the toggle support 15 may be the same as the guide 17 of the movable platen 13.

In this embodiment, the fixed platen 12 is fixed to the frame Fr, and the toggle support 15 is movable with respect to the frame Fr in the mold opening and closing direction. However, the toggle support 15 is fixed to the frame Fr, and the fixed platen 12 is fixed to the frame Fr. 12 may be movable in the mold opening and closing direction with respect to the frame Fr.

The tie bar 16 connects the fixed platen 12 and the toggle support 15 at an interval. A plurality of tie bars 16 are used. Each tie bar 16 is parallel to the mold opening / closing direction and extends in accordance with the mold clamping force.

The toggle mechanism 20 is provided between the movable platen 13 and the toggle support 15. The toggle mechanism 20 includes a crosshead 20a, a plurality of

links

20b, 20c, and the like. One link 20b is swingably attached to the movable platen 13, and the other link 20c is swingably attached to the toggle support 15. These

links

20b and 20c are flexibly connected by pins or the like. By moving the crosshead 20a back and forth, the plurality of

links

20b and 20c are bent and extended, and the movable platen 13 is moved forward and backward with respect to the toggle support 15.

The mold clamping motor 21 is attached to the toggle support 15. The mold clamping motor 21 moves the movable platen 13 forward and backward by moving the crosshead 20a forward and backward. A movement conversion mechanism is provided between the mold clamping motor 21 and the crosshead 20a for converting the rotational movement of the mold clamping motor 21 into a linear movement and transmitting the linear movement to the crosshead 20a. The motion conversion mechanism is composed of, for example, a ball screw mechanism.

The mold clamping device 10 performs a mold closing step, a pressure increasing step, a mold clamping step, a depressurizing step, a mold opening step, and the like under the control of the controller 90. In addition, under the control of the controller 90, the injection molding machine performs a weighing step, a mold closing step, a pressurizing step, a mold clamping step, a filling step, a pressure holding step, a cooling step, a depressurizing step, a mold opening step, an ejection step, and the like. Is repeated to produce a molded article repeatedly. A series of operations for obtaining a molded product, for example, operations from the start of a weighing process to the start of the next weighing process, are also called “shots” or “molding cycles”. The time required for one shot is also referred to as “molding cycle time” or “cycle time”.

One molding cycle includes, for example, a measuring step, a mold closing step, a pressurizing step, a mold clamping step, a filling step, a pressure keeping step, a cooling step, a depressurizing step, a mold opening step, and an ejection step in this order. The order here is the order in which each step starts. The filling step, the pressure holding step, and the cooling step are performed during the mold clamping step. The end of the depressurization step coincides with the start of the mold opening step.

In the measuring step, a measuring motor of an injection device (not shown) is driven to rotate a screw of the injection device (not shown) at a set rotation speed, and the molding material is fed forward along a spiral groove of the screw. Along with this, the molding material is gradually melted. As the liquid molding material is fed to the front of the screw and accumulates at the front of the cylinder of an injection device (not shown), the screw is retracted.

In the mold closing step, the movable platen 13 is moved forward by moving the cross head 20a to the mold closing completion position at the set moving speed by driving the mold clamping motor 21 to make the movable mold 33 touch the fixed mold 32. .

In the step-up step, a mold clamping force is generated by further driving the mold clamping motor 21 to further advance the crosshead 20a from the mold closing position to the mold clamping position. At the time of mold clamping, a cavity space (not shown) is formed between the movable mold 33 and the fixed mold 32.

では In the mold clamping process, the mold clamping force generated in the pressure increasing process is maintained.

In the filling step, the injection motor of the injection device is driven to advance the screw of the injection device at the set moving speed, and the liquid molding material accumulated in front of the screw is filled in the cavity space in the mold device 30.

In the pressure holding step, the injection motor of the injection device (not shown) is driven to push the screw of the injection device forward, and the pressure of the molding material at the front end of the screw (hereinafter also referred to as “holding pressure”) is maintained at a set pressure. Then, the molding material remaining in the cylinder of the injection device is pushed toward the mold device 30. Insufficient molding material due to cooling shrinkage in the mold apparatus 30 can be replenished. The filling step and the pressure holding step are collectively referred to as an injection step.

後 After the pressure holding step, the cooling step is started. In the cooling step, the molding material in the cavity space is solidified. A metering step may be performed during the cooling step for the purpose of shortening the molding cycle time.

In the depressurizing step, the movable platen 13 is retracted by driving the mold clamping motor 21 to retract the crosshead 20a from the mold clamping position to the mold opening start position, thereby reducing the mold clamping force. The mold opening start position and the mold closing completion position may be the same position.

In the mold opening step, the movable platen 13 is retracted by moving the cross head 20a from the mold opening start position to the mold opening completion position at the set moving speed by driving the mold clamping motor 21 to move the movable mold 33 to the fixed mold. Separate from the mold 32.

In the ejecting step, the ejector rod of the ejector device (not shown) is advanced from the standby position to the ejecting position at the set moving speed, whereby the movable member (not shown) of the mold device 30 is advanced to eject the molded product. Thereafter, the ejector rod is retracted at the set moving speed, and the movable member is retracted to the original standby position.

(4) When the thickness of the mold device 30 changes due to replacement of the mold device 30 or a change in the temperature of the mold device 30, mold thickness adjustment is performed so that a predetermined mold clamping force is obtained at the time of mold clamping. In the mold thickness adjustment, for example, the distance L between the fixed platen 12 and the toggle support 15 is set so that the link angle of the toggle mechanism 20 becomes a predetermined angle at the time of mold touch when the movable mold 33 touches the fixed mold 32. adjust.

The mold clamping device 10 has a mold thickness adjusting mechanism 22. The mold thickness adjusting mechanism 22 adjusts the mold thickness by adjusting the distance L between the fixed platen 12 and the toggle support 15. The timing of the mold thickness adjustment is performed, for example, after the end of the molding cycle and before the start of the next molding cycle. The mold thickness adjusting mechanism 22 is screwed to the screw shaft 22a formed at, for example, the rear end of the tie bar 16, a screw nut 22b rotatably held by the toggle support 15 and unable to advance and retreat. A mold thickness adjusting motor 22c for rotating the screw nut 22b.

The screw shaft 22a and the screw nut 22b are provided for each tie bar 16. The rotational driving force of the mold thickness adjusting motor 22c may be transmitted to the plurality of screw nuts 22b via the rotational driving force transmitting unit 22e. The plurality of screw nuts 22b can be rotated synchronously. It is also possible to individually rotate the plurality of screw nuts 22b by changing the transmission path of the rotational driving force transmission unit 22e.

Rotation drive force transmission part 22e is constituted by a gear, for example. In this case, a passive gear is formed on the outer periphery of each screw nut 22b, a driving gear is mounted on the output shaft of the mold thickness adjusting motor 22c, and a plurality of passive gears and an intermediate gear meshing with the driving gear are provided at the central portion of the toggle support 15. Is held rotatably. Note that the rotational driving force transmission unit 22e may be configured by a belt, a pulley, or the like, instead of the gear.

The operation of the mold thickness adjusting mechanism 22 is controlled by the controller 90. The controller 90 drives the mold thickness adjusting motor 22c to rotate the screw nut 22b. As a result, the position of the toggle support 15 with respect to the tie bar 16 is adjusted, and the distance L between the fixed platen 12 and the toggle support 15 is adjusted. Note that a plurality of mold thickness adjusting mechanisms may be used in combination.

The interval L is detected using the mold thickness adjustment motor encoder 22d. The mold thickness adjustment motor encoder 22d detects the amount and direction of rotation of the mold thickness adjustment motor 22c, and sends a signal indicating the detection result to the controller 90. The detection result of the mold thickness adjusting motor encoder 22d is used for monitoring and controlling the position and the interval L of the toggle support 15. Note that the toggle support position detector for detecting the position of the toggle support 15 and the interval detector for detecting the interval L are not limited to the mold thickness adjustment motor encoder 22d, but general ones can be used.

The mold clamping device 10 of the present embodiment has the mold clamping motor 21 as a drive source for moving the movable platen 13, but may have a hydraulic cylinder instead of the mold clamping motor 21. Further, the mold clamping device 10 may have a linear motor for opening and closing the mold, and may have an electromagnet for clamping.

FIG. 3 is a view showing a positional relationship of a tie bar of the injection molding machine according to one embodiment, and is a view of a fixed platen viewed from a movable platen side. The injection molding machine has four tie bars 16. The four tie bars 16 are vertically symmetrically arranged about the horizontal line L1 and symmetrically arranged about the vertical line L2 in the mold opening and closing direction. The upper side of the horizontal line L1 is called a top side, and the lower side of the horizontal line L1 is called a ground side. The operation device 70 side with respect to the vertical line L2 is referred to as an operation side, and the side opposite to the operation device 70 with respect to the vertical line L2 is referred to as a non-operation side.

The mold clamping force is distributed and applied to the four tie bars 16, and each tie bar 16 extends. The force that resists the elongation of each tie bar 16 is called the axial force. When there is a difference between the effective lengths of the four tie bars 16, there is a difference in axial force between the tie bar 16 having a short effective length and the tie bar 16 having a long effective length. Here, the effective length of the tie bar 16 refers to an interval between the fixed platen 12 and the toggle support 15 connected by the tie bar 16, and is measured, for example, in a state where no mold clamping force is applied.

軸 By adjusting the effective length of the tie bar 16, the balance of the axial force can be adjusted. The balance of the axial force is set, for example, so that the surface pressure of the fixed mold 32 and the movable mold 33 has a target distribution at the time of mold clamping. The target distribution may be either a uniform distribution or a non-uniform distribution, and is set according to the situation. Molding defects can be reduced.

Since the tie bar 16 is formed of a metal material, the effective length of the tie bar 16 changes according to the temperature of the tie bar 16. As the temperature of the tie bar 16 increases, the effective length of the tie bar 16 increases. By adjusting the temperature of the tie bar 16, the effective length of the tie bar 16 can be adjusted, and the balance of the axial force can be adjusted.

Therefore, a heater 25, a temperature detector 27, an axial force detector 28, and the like are attached to each tie bar 16, as shown in FIGS. The heater 25, the temperature detector 27, the axial force detector 28, and the like are provided in the mold clamping device 10.

The heater 25 heats the tie bar 16 in order to adjust the effective length of the tie bar 16. The portion of the tie bar 16 heated by the heater 25 is called a heating unit. The heater 25 is composed of, for example, an electric heater such as a heater. In addition, the heater 25 is not limited to an electric heater, and may be configured with, for example, a warm water jacket.

The temperature detector 27 detects the temperature of the tie bar 16 heated by the heater 25 and cooled by natural cooling. For example, the temperature detector 27 is disposed near the heater 25 and detects the temperature of the heating part of the tie bar. The temperature detector 27 outputs a detection result to the controller 90.

The controller 90 controls the heater 25 so that the actual value of the temperature of the heating section of the tie bar 16 becomes a set value. The control may be either feedback control or feedforward control.

The controller 90 of the present embodiment controls the heater 25.

The axial force detector 28 detects the axial force of the tie bar 16 heated by the heater 25 and cooled by natural cooling. The axial force detector 28 is, for example, a strain gauge type, and detects the axial force of the tie bar 16 by detecting the strain of the tie bar 16.

The axial force detector 28 of the above embodiment is of a strain gauge type, but may be of a piezoelectric type, a capacitive type, a hydraulic type, an electromagnetic type, or the like.

The axial force detector 28 outputs the detection result to the controller 90. The controller 90 may set the heating temperature of the tie bar 16 heated by the heater 25 so that the actual value of the axial force detected by the axial force detector 28 becomes a set value.

Here, in the injection molding machine according to one embodiment, when increasing the temperature of the tie bar 16, the heater 25 is operated to increase the temperature. On the other hand, when lowering the temperature of the tie bar 16, the heater 25 is stopped, and the temperature is lowered by natural cooling (natural heat radiation and heat conduction to other members). As described above, since the temperature of the tie bar 16 can be changed only by turning on / off the heater 25, the control can be prevented from being discontinuous, and the controllability can be prevented from deteriorating.

By the way, due to such a configuration, the response speed when lowering the temperature of the tie bar 16 is slower than the response speed when increasing the temperature. Further, when lowering the temperature of the tie bar 16, the temperature cannot be reduced below a predetermined temperature (for example, the atmospheric temperature).

Next, the axial force control of the injection molding machine according to one embodiment will be described with reference to FIG. FIG. 4 is a block diagram illustrating an example of axial force control of the injection molding machine according to one embodiment.

The axial force command unit 910 is provided in the controller 90, for example. The axial force command unit 910 instructs an axial force command (axial force set value) of each tie bar 16 to the axial force control unit 920. Regarding the four tie bars 16 shown in FIG. 3, the upper left is the first tie bar, the lower left is the second tie bar, the upper right is the third tie bar, and the lower right is the fourth tie bar. The operator inputs the axial force setting values of the first to fourth tie bars to the controller 90 via the operation device 70. Accordingly, the axial force command unit 910 calculates the axial force set value Ncmd1, the second tie bar axial force set value Ncmd2, the axial force set value Ncmd3 of the third tie bar, and the axial force set value Ncmd4 of the fourth tie bar. It is output to the axial force control unit 920 as an axial force command.

The axial force control unit 920 is provided in the controller 90, for example. The axial force control unit 920 determines the heater 25 based on the axial force set values (Ncmd1 to Ncmd4) of the axial force command unit 910 and the axial force detection values (Nfb1 to Nfb4 described later) detected by the axial force detector 28. To control the temperature of the tie bar 16.

The axial force controller 920 includes a temperature command generator 921, a current command generator 922, a temperature calculator 923, an axial force calculator 924,

calculators

925, 926, and a correction calculator 927. I have.

The computing unit 925 receives the axial force setting values (Ncmd1 to Ncmd4) of each tie bar 16 from the axial force command unit 910, and outputs the axial force detection values (Nfb1 to Nfb4) of each tie bar 16 from the axial force calculating unit 924 described later. Then, the difference (Ncmd1-Nfb1,..., Ncmd4-Nfb4) between the axial force setting value and the axial force detection value of each tie bar 16 is output.

The temperature command generation unit 921 calculates the temperature change amount of each tie bar 16 based on the output value of the calculator 925 such that the difference between the axial force set value and the detected axial force is small (deviation reduction processing). For example, the temperature command generator 921 has a table indicating the relationship between the temperature rise of the tie bar 16 and the axial force rise. The table is configured such that the axial force decreases as the temperature of the tie bar 16 increases. The temperature command generation unit 921 calculates the temperature change amount of each tie bar 16 from the difference between the axial force setting value and the axial force detection value based on a table, for example. That is, when the detected axial force value is lower than the set axial force value, a temperature change amount for lowering the temperature of the tie bar 16 is calculated. On the other hand, when the detected axial force is higher than the set axial force, a temperature change amount for increasing the temperature of the tie bar 16 is calculated.

(4) The temperature command generation unit 921 generates a new target temperature for each tie bar 16 based on the temperature change amount of each tie bar 16 and the current target temperature of each tie bar 16. The temperature command generation unit 921 calculates the generated target temperature (the target temperature Tcmd1 of the first tie bar, the target temperature Tcmd2 of the second tie bar, the target temperature Tcmd3 of the third tie bar, and the target temperature Tcmd4 of the fourth tie bar) as a temperature command. Output to the output unit 926.

The computing unit 926 receives the target temperatures (Tcmd1 to Tcmd4) of the tie bars 16 from the temperature command generation unit 921, and the temperature detection values (Tfb1 to Tfb4) of the tie bars 16 from the temperature calculation unit 923 described later. The difference between the target temperature of the tie bar 16 and the detected temperature value (Tcmd1-Tfb1,..., Tcmd4-Tfb4) is output.

The current command generator 922 outputs a control signal to the relay 25b corresponding to the heater 25 of each tie bar 16 based on the output value of the calculator 926 so that the deviation between the target temperature and the detected temperature value is reduced. Relay 25b controls power supply from heater power supply 25a to heater 25 based on a control signal from current command generator 922. Here, when the detected temperature value is higher than the target temperature, the current command generator 922 outputs a control signal for turning off the heater 25. When the detected temperature value is lower than the target temperature, current command generator 922 outputs a control signal for turning on heater 25. When the heater 25 is turned on, the power supplied from the heater power supply 25a to the heater 25 may be controlled by changing the duty ratio of the control signal according to the difference between the target temperature and the detected temperature value. The tie bar 16 is heated by supplying power from the heater power supply 25a to the heater 25.

The temperature calculation unit 923 calculates the temperature of the tie bar 16 based on the detection signal of the temperature detector 27. In addition, the temperature detector 27 is provided in each tie bar 16 respectively. The calculated temperature of the tie bar 16 (the temperature detection value Tfb1 of the first tie bar, the temperature detection value Tfb2 of the second tie bar, the temperature detection value Tfb3 of the third tie bar, and the temperature detection value Tfb4 of the fourth tie bar) are sent to the calculator 926. Is output.

The axial force calculator 924 calculates the axial force of the tie bar 16 based on the detection signal of the axial force detector 28. The axial force detector 28 is provided on each tie bar 16. The calculated axial force of the tie bar 16 (the axial force detected value Nfb1, the axial force detected value Nfb2 of the second tie bar, the axial force detected value Nfb3 of the third tie bar, and the axial force detected value Nfb4 of the fourth tie bar) is Are output to the arithmetic unit 925.

The correction calculation unit 927 receives the difference between the target temperature of each tie bar 16 and the detected temperature value (Tcmd1−Tfb1,..., Tcmd4−Tfb4) output from the calculator 926. The correction calculation unit 927 determines the presence or absence of the tie bar 16 of which the temperature decrease has been instructed, among the four tie bars 16. Here, the instruction for lowering the temperature is an instruction for lowering the temperature of the tie bar 16 and means that the output from the computing unit 926 “target temperature-temperature detection value” is a negative value. The temperature increase command is a command to increase the temperature of the tie bar 16 and refers to a case where the "target temperature-temperature detection value" output from the calculator 926 is a positive value.

If there is a tie bar 16 for which a temperature decrease has been instructed, the correction calculation unit 927 outputs a command to the axial force command unit 910 to reduce the axial force set value. For example, the axial force offset amount Ns is output. The axial force offset amount Ns may be a predetermined value, or may be a value that changes according to the temperature decrease amount (difference between the target temperature and the temperature detection value) of the tie bar 16 to which the temperature decrease is instructed. Good.

Upon receiving a command to reduce the axial force set value from the correction calculating unit 927, the axial force command unit 910 reduces the axial force set value of each tie bar 16. For example, assuming the offset amount Ns of the axial force to be reduced, the axial force set value Ncmd1-Ns of the first tie bar, the axial force set value Ncmd2-Ns of the second tie bar, the axial force set value Ncmd3-Ns of the third tie bar, The axial force setting value Ncmd4-Ns of the four tie bars is output to the axial force control unit 920 as a new axial force command.

目標 By reducing the axial force set value of each tie bar 16 in this way, the target temperature generated by the temperature command generation unit 921 increases. For example, assuming that a temperature offset amount corresponding to the axial force offset amount Ns is Ts, the temperature command generation unit 921 determines that the target temperature Tcmd1 + Ts of the first tie bar, the target temperature Tcmd2 + Ts of the second tie bar, the target temperature Tcmd3 + Ts of the third tie bar, The target temperature Tcmd4 + Ts of the four tie bars is output to the calculator 926 as a new temperature command.

により Thereby, the target temperature can be raised while maintaining the temperature difference between the target temperatures of the four tie bars 16. Since the temperature difference between the target temperatures of the four tie bars 16 can be maintained, the balance of the axial force, for example, the balance of the axial force in the vertical direction (the set of the first and third tie bars and the set of the second and fourth tie bars, ), Horizontal axial force balance (relationship between the first and second tie-bar sets and third and fourth tie-bar sets), and torsional axial force balance (the first and fourth tie-bar sets and the 2, the relationship with the set of the third tie bar) can be adjusted.

Further, for the tie bar 16 whose temperature detection value is higher than the target temperature, the target temperature can be increased by the correction calculation unit 927, so that the amount of temperature decrease can be reduced and the time required for natural cooling can be reduced. It can be reduced and the responsiveness is improved. When the axial force offset amount Ns of the correction calculation unit 927 is increased, the temperature offset amount Ts is also increased, and the difference between the target temperature output from the calculator 926 and the detected temperature value is set to 0 or more in all the tie bars 16. Can be. Thereby, the axial force can be controlled by the temperature rise of the tie bar 16 by the heater 25 having good response, so that the response is further improved.

The correction operation unit 927 determines whether there is a command to lower the temperature of the tie bar 16 based on the output of the calculator 926. However, the correction calculation unit 927 determines whether there is a command to lower the temperature of the tie bar 16 based on the output of the calculator 925. You may. That is, when the “axial force setting value−axial force detection value” output from the computing unit 925 is positive, the correction arithmetic unit 927 determines that a command to lower the temperature of the tie bar 16 has been issued, and Decrease the set value.

As described above, in the axial force control shown in FIG. 4, when the detected axial force value of any of the tie bars 16 is lower than the set axial force value (when the detected temperature value of the tie bar 16 is higher than the target temperature), In the above, the configuration for reducing the set value of the axial force was shown. Another axial force control will be described with reference to FIGS.

FIG. 5 is a block diagram showing another example of the axial force control of the injection molding machine according to one embodiment. In the axial force control shown in FIG. 5, when the detected axial force value of any of the tie bars 16 is lower than the set axial force value (the detected temperature value of the tie bar 16 is higher than the target temperature), 4 shows a configuration for increasing (offsetting) a force detection value.

The axial force controller 920A includes a temperature command generator 921, a current command generator 922, a temperature calculator 923, an axial force calculator 924, calculators 925A and 926, and a correction calculator 927A. I have. The axial force control unit 920A illustrated in FIG. 5 differs from the axial force control unit 920 illustrated in FIG. 4 in the configuration of the correction arithmetic unit 927A and the arithmetic unit 925A. Other configurations are the same, and redundant description will be omitted.

The correction operation unit 927A receives the difference between the target temperature of each tie bar 16 and the detected temperature value (Tcmd1-Tfb1,..., Tcmd4-Tfb4) output from the operation unit 926. The correction calculation unit 927A determines whether or not there is a tie bar 16 for which a temperature decrease has been instructed, among the four tie bars 16. If there is a tie bar 16 for which a temperature decrease has been instructed, the correction calculation unit 927A outputs a command to increase (offset) the axial force detection value. For example, the axial force offset amount Ns is output. The axial force offset amount Ns may be a predetermined value, or may be a value that changes according to the temperature decrease amount (difference between the target temperature and the temperature detection value) of the tie bar 16 to which the temperature decrease is instructed. Good.

The computing unit 925A receives the axial force setting values (Ncmd1 to Ncmd4) of each tie bar 16 from the axial force command unit 910, and receives the axial force detection values (Nfb1 to Nfb4) of each tie bar 16 from the axial force calculation unit 924. , The axial force offset amount Ns is input from the correction operation unit 927A, and the difference (Ncmd1-Nfb1-Ns,..., Ncmd4-Nfb4-Ns) between the axial force set value of each tie bar 16 and the offset axial force detection value is output. I do.

With such a configuration, in the axial force control shown in FIG. 5 as well, the responsiveness can be improved while adjusting the balance of the axial force, similarly to the axial force control shown in FIG.

Although the correction calculation unit 927A determines whether or not there is a command to lower the temperature of the tie bar 16 based on the output of the calculator 926, it determines whether or not there is a command to lower the temperature of the tie bar 16 based on the output of the calculator 925A. You may. That is, when the “axial force set value−axial force detected value” output from the calculator 925 is positive, the correction arithmetic unit 927A determines that a command to decrease the temperature of the tie bar 16 has been issued, and The detection value may be increased.

FIG. 6 is a block diagram showing still another example of the axial force control of the injection molding machine according to one embodiment. In the axial force control shown in FIG. 6, when the detected axial force value of any of the tie bars 16 is lower than the set axial force value (when the detected temperature value of the tie bar 16 is higher than the target temperature), 3 shows a configuration for increasing (offsetting) the temperature.

The axial force controller 920B includes a temperature command generator 921, a current command generator 922, a temperature calculator 923, an axial force calculator 924,

calculators

925, 926, 928B, and a correction calculator 927B. Have. The axial force control unit 920B illustrated in FIG. 6 is different from the axial force control unit 920 illustrated in FIG. 4 in the configuration of the correction arithmetic unit 927B and the arithmetic unit 928B. Other configurations are the same, and redundant description will be omitted.

The correction calculation unit 927B receives the difference between the target temperature of each tie bar 16 and the detected temperature value (Tcmd1-Tfb1,..., Tcmd4-Tfb4) output from the calculator 926. The correction calculating unit 927B determines the presence or absence of the tie bar 16 of which the temperature reduction has been instructed, among the four tie bars 16. If there is a tie bar 16 for which a temperature decrease has been instructed, the correction calculation unit 927B outputs a command to increase the target temperature. For example, a temperature offset amount Ts is output. The temperature offset amount Ts may be a predetermined value, or may be a value that changes according to the temperature decrease amount (difference between the target temperature and the temperature detection value) of the tie bar 16 to which the temperature decrease has been instructed. .

The computing unit 928B receives the target temperatures (Tcmd1 to Tcmd4) of the tie bars 16 from the temperature command generating unit 921, the temperature offset amount Ts from the correction computing unit 927B described later, and inputs a new target temperature ( Tcmd1 + Ts,..., Tcmd4 + Ts). The new target temperature (Tcmd1 + Ts,..., Tcmd4 + Ts) is input to the calculator 926.

According to such a configuration, in the axial force control shown in FIG. 6 as well, the responsiveness can be improved while adjusting the balance of the axial force, similarly to the axial force control shown in FIG.

The correction operation unit 927B determines whether or not there is a command to lower the temperature of the tie bar 16 based on the output of the calculator 926. However, the correction calculator 927B determines whether or not there is a command to lower the temperature of the tie bar 16 based on the output of the calculator 925. You may. That is, when the “axial force set value−axial force detected value” output from the arithmetic unit 925 is positive, the correction arithmetic unit 927B determines that a command to lower the temperature of the tie bar 16 has been issued, and determines the target temperature. May be raised.

FIG. 7 is a graph showing an example of the temperature of each tie bar and the mold clamping force in the axial force control of the injection molding machine according to one embodiment. In the upper graph, the horizontal axis represents the number of shots, the vertical axis represents the temperature, T1 represents the temperature of the first tie bar, T2 represents the temperature of the second tie bar, T3 represents the temperature of the third tie bar, and T4 represents the temperature of the fourth tie bar. Temperature. In the lower graph, the horizontal axis represents the number of shots, and the vertical axis represents the detected value of the mold clamping force during mold clamping. The vertical axis may be an average value of the detected values of the mold clamping force during the mold clamping process. The vertical axis may be the maximum value of the mold clamping force during the mold clamping process. The mold clamping force is the sum of the axial forces of the first to fourth tie bars (Nfb1 + Nfb2 + Nfb3 + Nfb4). That is, the axial force detector 28 also functions as a mold clamping force detector that detects the mold clamping force.

軸 The axial force control of the injection molding machine according to one embodiment is started (control ON). As shown in the upper graph, the tie bar 16 is heated or the axial force is controlled so as to maintain the temperature. In the example shown in FIG. 7, the temperatures T2 to T4 of the second to fourth tie bars are increased while maintaining the temperature T1 of the first tie bar. This improves the responsiveness of the axial force control while adjusting the balance of the axial force.

By the way, the instruction to decrease the temperature of the tie bar 16 is set to increase the target temperature, thereby reducing the amount of decrease in the temperature or increasing the temperature. Normally, when the temperature is lowered, the amount of reduction is reduced or the temperature is raised, so that the axial force of the tie bar 16 is reduced. That is, the axial force is reduced by the amount of the temperature offset. As shown in the lower graph, the actual value of the mold clamping force decreases. When the actual value of the mold clamping force becomes smaller than the set value by a predetermined value or more, the controller 90 controls the mold thickness adjusting mechanism 22 so that the actual value of the mold clamping force approaches the set value, thereby reducing the interval L. Then, the position of the toggle support 15 is advanced toward the fixed platen 12. Thereby, a desired mold clamping force can be recovered (mold clamping force correction). The timing of the mold clamping force correction is performed, for example, after the end of the molding cycle and before the start of the next molding cycle.

In the example shown in FIG. 7, the axial force command is changed during the axial force control (command change). In the example shown in FIG. 7, the temperatures T1, T3, and T4 of the first, third, and fourth tie bars are increased while maintaining the temperature T2 of the second tie bar.

When the difference between the detected axial force value and the set axial force value converges within a predetermined range, as shown in FIG. 7, the correction calculation unit 927 maintains the relative temperature difference between the four tie bars 16 and The temperature of 16 is lowered. Thereby, the temperature of the tie bar 16 can be reduced while maintaining the balance of the axial force. Further, as the temperature of the tie bars 16 decreases, the axial force of each tie bar 16 also increases, and the mold clamping force can be recovered.

Although not shown, when the temperature of the tie bar 16 becomes equal to or higher than a predetermined first threshold temperature, the correction calculation unit 927 may perform control to lower the target temperature. Thus, it is possible to prevent the tie bar 16 from becoming too hot. At this time, the temperature of the tie bar 16 is lowered while maintaining the relative temperature difference between the four tie bars 16. Thereby, the temperature of the tie bar 16 can be reduced while maintaining the balance of the axial force. When the temperature of the tie bar 16 becomes equal to or lower than the predetermined second threshold temperature, the above-described axial force control may be restarted.

The embodiments of the injection molding machine and the like have been described above. However, the present invention is not limited to the embodiments and the like, and various modifications and changes may be made within the scope of the invention described in the appended claims. Improvements are possible.

The injection molding machine may include a heating range restricting unit that restricts a heating range of the tie bar 16 heated by the heater 25. The heating range limiting means is constituted by, for example, coolers disposed on both sides of the tie bar 16 in the axial direction with the heater 25 interposed therebetween. The cooler is composed of, for example, a water cooling jacket. In addition, the cooler is not limited to the water cooling jacket, and may be configured by, for example, a cooling fin. The cooling method of the cooling fins may be either a forced air cooling method using a cooling fan or a natural air cooling method. By the heating range limiting means, the movement of the heat applied to the tie bar 16 by the heater 25 can be limited, the time required for the temperature of the entire mold clamping device 10 to be stabilized can be reduced, and the balance of the axial force can be stabilized. You can save time. Further, the thermal expansion range of the tie bar 16 can be managed, the amount of change in the effective length due to the temperature change of the tie bar 16 can be managed with high accuracy, and the axial force can be adjusted with high accuracy. Further, the heating range limiting means is not limited to the cooler, and may have any configuration as long as it can limit the movement of heat. That is, it is only necessary that heat insulation be provided between the heating range and the outside of the heating range.

The controller 90 controls the cooler so as to limit the heating range of the tie bar 16. In this case, the controller 90 may control the cooler so that the actual value of the temperature of the cooling unit of the tie bar 16 becomes the set value. The temperature of the cooling section of the tie bar 16 is detected by a temperature detector different from the temperature detector 27. This temperature detector is arranged near the cooler. The controller 90 controls the temperature by the heater 25 in a state where the heating range limiting unit is operated. That is, the temperature control by the heating range limiting means and the heater 25 is performed simultaneously.

Although the injection molding machine according to one embodiment has been described as being provided with the axial force detectors 28 on four tie bars, the invention is not limited to this. At least the tie bars 16 arranged above and below the mold device 30 and / or the tie bars 16 arranged right and left of the mold device 30 may be arranged. By providing the axial force detectors 28 on the tie bars 16 arranged above and below the mold device 30, the balance of the axial force in the vertical direction can be adjusted. By providing the axial force detectors 28 on the tie bars 16 arranged on the left and right sides of the mold device 30, the balance of the axial force in the horizontal direction can be adjusted. Further, the number of detectors can be reduced.

Also, the injection molding machine according to one embodiment has been described as adjusting the axial force of the tie bar 16 in a direction in which the tie bar 16 is heated from the steady temperature using the heater 25 controlled by the controller 90. However, it is not limited to this. That is, a configuration in which a cooler controlled by the controller 90 is provided instead of the heater 25 and the axial force of the tie bar 16 is adjusted in a direction in which the tie bar 16 is cooled below the steady temperature may be employed.

Here, in an injection molding machine having a cooler in place of the heater 25, when the temperature of the tie bar 16 is lowered, the temperature is lowered by operating the cooler. On the other hand, when raising the temperature of the tie bar 16, the temperature is raised by stopping the cooler. As described above, since the temperature of the tie bar 16 can be changed only by turning on / off the cooler, the control can be prevented from being discontinuous, and the controllability can be prevented from deteriorating.

By the way, due to such a configuration, the response speed when increasing the temperature of the tie bar 16 is lower than the response speed when decreasing the temperature. In addition, when the temperature of the tie bar 16 is raised, it cannot be raised above a predetermined temperature (for example, atmospheric temperature).

In this case, when there is a tie bar 16 for which a temperature increase is instructed in any of the tie bars 16, the correction calculation unit increases the axial force set value in all the tie bars 16. In addition, when there is a tie bar 16 for which a temperature increase is instructed in any of the tie bars 16, the correction calculation unit may decrease the axial force detection value in all the tie bars 16. Further, when there is a tie bar 16 for which a temperature increase is instructed in any of the tie bars 16, the correction calculation unit may decrease the target temperature in all the tie bars 16.

With this, for the tie bar 16 whose temperature detection value is lower than the target temperature, the target temperature can be reduced by the correction calculation unit, so that the amount of temperature rise can be reduced and the balance of axial force can be adjusted. And the responsiveness is improved.

This application claims priority based on Japanese Patent Application No. 2018-158629 filed on Aug. 27, 2018, the entire contents of which are incorporated herein by reference.

10 Mold Clamping Device 16 Tie Bar 22 Mold Thickness Adjusting Mechanism 25 Heater 27 Temperature Detector 28 Axial Force Detector 90 Controller 910 Axial Force Command Units 920, 920A, 920B Axial Force Control Unit 921 Temperature Command Generation Unit Part)
922 Current command generation unit 923 Temperature calculation unit 924 Axial

force calculation units

925, 925A, 926,

928B Operators

927, 927A, 927B Correction calculation unit (axial force control command generation unit)

Claims

A mold clamping device having a plurality of tie bars,
A tie bar axial force adjusting device for adjusting the axial force of the tie bar, and an injection molding machine,
The tie bar axial force adjusting device,
An axial force detector for detecting an axial force of the tie bar;
An axial force control unit that controls the temperature of the tie bar based on a deviation between a detected value and a set value of the axial force of the tie bar,
The axial force detector is provided on the plurality of tie bars,
The axial force control unit, when the detected value of the axial force of the tie bar is higher than a set value, has an axial force control command generation unit that generates a control command to increase the temperature of the tie bar,
When the detected value of the axial force of the tie bar is lower than a set value, the axial force control command generation unit performs a deviation reduction process to reduce a deviation between the detected value and the set value, and the amount of decrease in the temperature of the tie bar. Injection molding machine.
2. The injection molding machine according to claim 1, wherein the axial force control unit has a heater that heats the tie bar, and stops the heater to lower the temperature of the tie bar. 3.
3. The injection molding machine according to claim 1, wherein the axial force control command generation unit reduces the set value of the axial force when the detected value of the axial force of the tie bar is lower than a set value. 4.
4. The axial force control command generator according to claim 1, wherein when the detected value of the axial force of the tie bar is lower than a set value, the detected value of the axial force is increased. 5. Injection molding machine.
The said axial force control command production | generation part adds the control command which raises the temperature of the said tie bar when the detected value of the axial force of the said tie bar is lower than a set value, The one of Claim 1 thru | or 4 characterized by the above-mentioned. 3. The injection molding machine according to claim 1.
2. The axial force control command generator, when a difference between a detected value of the axial force of the tie bar and a set value falls within a predetermined range, generates a control command to decrease the temperature of the tie bar. 3. The injection molding machine according to claim 1.
The axial force control unit has a tie bar temperature detector that detects the temperature of the tie bar,
The said axial force control command production | generation part produces | generates the control command which reduces the temperature of the said tie-bar, when the said tie-bar temperature detector detects that the temperature of the said tie-bar rose to predetermined temperature. 7. The injection molding machine according to any one of 6.
8. The injection molding machine according to claim 6, wherein the axial force control command generation unit generates a control command for lowering the temperature of each tie bar while maintaining the temperature difference between the plurality of tie bars. 9.
The mold clamping device has a toggle mechanism for moving the movable platen back and forth, and a toggle support to which the toggle mechanism is connected,
A control unit for controlling the mold clamping device,
The controller controls the toggle so that the actual value of the mold clamping force approaches a set value when the actual value of the mold clamping force becomes smaller than a set value by a predetermined value or more due to heating of the tie bar by the tie bar axial force adjusting device. The injection molding machine according to any one of claims 1 to 8, wherein a position of the support is changed.
A mold clamping device having a plurality of tie bars,
A tie bar axial force adjusting device for adjusting the axial force of the tie bar, and an injection molding machine,
The tie bar axial force adjusting device,
An axial force detector for detecting an axial force of the tie bar;
An axial force control unit that controls the temperature of the tie bar based on a deviation between a detected value and a set value of the axial force of the tie bar,
The axial force detector is provided on the plurality of tie bars,
The axial force control unit, when the detected value of the axial force of the tie bar is lower than a set value, has an axial force control command generation unit that generates a control command to reduce the temperature of the tie bar,
When the detected value of the axial force of the tie bar is higher than a set value, the axial force control command generation unit performs a deviation reducing process to reduce a deviation between the detected value and the set value, and increases the temperature of the tie bar. Injection molding machine.
The injection molding machine according to claim 10, wherein the axial force control unit includes a cooler that cools the tie bar, and stops the cooler to increase the temperature of the tie bar.
The injection molding machine according to any one of claims 1 to 11, wherein the axial force detector also functions as a mold clamping force detector that detects a mold clamping force.
A plurality of the tie bars are arranged around the mold apparatus,
13. The axial force detector is arranged at least on tie bars arranged above and below the mold device and / or tie bars arranged on the left and right sides of the mold device. The injection molding machine according to any one of the above.