CN116787722A

CN116787722A - Injection molding machine

Info

Publication number: CN116787722A
Application number: CN202310897361.XA
Authority: CN
Inventors: 堀田大吾; 大石洁; 横仓勇希; 松井佑树
Original assignee: Sumitomo Heavy Industries Ltd
Current assignee: Sumitomo Heavy Industries Ltd
Priority date: 2018-08-27
Filing date: 2019-08-26
Publication date: 2023-09-22
Also published as: WO2020045359A1; JP7175674B2; JP2020032544A; CN112638616A

Abstract

The application provides an injection molding machine capable of shortening the time until the balance of axial force becomes stable. An injection molding machine, comprising: a mold clamping device having a plurality of connecting rods; and a link lever axial force adjustment device that adjusts an axial force of the link lever, the link lever axial force adjustment device having: an axial force detector for detecting an axial force of the connecting rod; and a shaft force control unit that controls the temperature of the connecting rods in accordance with the deviation between the detected value of the shaft force of the connecting rods and a set value, wherein the shaft force detector is provided to the plurality of connecting rods, and wherein the shaft force control unit includes a shaft force control command generation unit that generates a control command for increasing the temperature of the connecting rods when the detected value of the shaft force of the connecting rods is higher than the set value, and wherein the shaft force control command generation unit performs a deviation reduction process for reducing the deviation between the detected value and the set value and reducing the amount of decrease in the temperature of the connecting rods when the detected value of the shaft force of the connecting rods is lower than the set value.

Description

Injection molding machine

The application is a divisional application of the application name of an injection molding machine, wherein the application date is 2019, 8, 26, 201980056432.5.

Technical Field

The present application relates to an injection molding machine.

Background

The injection molding machine has a mold clamping device for closing, clamping, and opening the mold device. The mold clamping device has a plurality of tie bars that extend in accordance with the mold clamping force. The mold clamping force is applied to the plurality of tie bars in a dispersed manner, and the tie bars are elongated. The force that counter-balances the elongation of the connecting rod is referred to as the axial force.

For example, in the case of multi-piece molding, if the balance of forces pressing the mold is poor, the thickness of each molded article may be different. In order to solve this problem, a method of controlling the temperature of the connecting rod to improve the balance of the force pressing the mold is being studied. Specifically, a method of raising/lowering the temperature of the connection rod by a heater/cooler (for example, refer to patent document 1).

Here, the switching between heating and cooling is controlled by the control discontinuity, and the controllability is deteriorated. Therefore, it is preferable to change the connecting rod temperature only by "on"/"off" of the heater without using a cooler.

Technical literature of the prior art

Patent literature

Patent document 1: japanese patent laid-open No. 2008-114513

Disclosure of Invention

Technical problem to be solved by the application

However, in the (natural cooling) method of stopping the heater to lower the temperature of the connecting rod, it takes time to lower to the prescribed temperature. Therefore, there is a problem that the yield is lowered and the starting time is prolonged.

The present application has been made in view of the above-described problems, and a main object of the present application is to provide an injection molding machine capable of shortening a time period until balance of axial force becomes stable.

Means for solving the technical problems

In order to solve the above-described problems, according to an aspect of the present application, there is provided an injection molding machine having:

a mold clamping device having a plurality of connecting rods; a kind of electronic device with high-pressure air-conditioning system

A connecting rod axial force adjusting device for adjusting the axial force of the connecting rod, wherein in the injection molding machine,

the connecting rod shaft force adjustment device includes:

an axial force detector for detecting an axial force of the connecting rod; a kind of electronic device with high-pressure air-conditioning system

An axial force control unit for controlling the temperature of the connecting rod according to the deviation between the detected value and the set value of the axial force of the connecting rod,

the axial force detector is arranged on the plurality of connecting rods,

the axial force control part is provided with an axial force control instruction generating part which generates a control instruction for raising the temperature of the connecting rod when the detected value of the axial force of the connecting rod is higher than a set value,

when the detected value of the axial force of the connecting rod is lower than a set value, the axial force control instruction generating section performs a deviation reducing process of reducing a deviation of the detected value from the set value, and reduces the amount of decrease in the temperature of the connecting rod.

Effects of the application

According to one aspect of the present application, there is provided an injection molding machine capable of shortening a time until balance of axial forces becomes stable.

Drawings

Fig. 1 is a diagram showing a state at the end of mold opening of an injection molding machine according to an embodiment.

Fig. 2 is a diagram showing a state at the time of mold closing of the injection molding machine according to the embodiment.

Fig. 3 is a diagram showing a positional relationship of a connecting rod of an injection molding machine according to an embodiment, and is a diagram in which a fixed platen is viewed from a movable platen side.

Fig. 4 is a block diagram showing an example of axial force control of the injection molding machine according to the embodiment.

Fig. 5 is a block diagram showing another example of axial force control of the injection molding machine according to the embodiment.

Fig. 6 is a block diagram showing still another example of axial force control of the injection molding machine according to the embodiment.

Fig. 7 is a graph showing an example of the temperature and clamping force of each tie bar at the time of controlling the axial force of the injection molding machine according to the embodiment.

Detailed Description

The mode for carrying out the present application will be described below with reference to the drawings, but in each of the drawings, the same or corresponding structures are denoted by the same or corresponding symbols and description thereof will be omitted.

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

The controller 90 includes a CPU (Central Processing Unit: central processing unit) 91 and a storage medium 92 such as a memory. The controller 90 causes the CPU91 to execute a program stored in the storage medium 92, thereby controlling the mold clamping device 10, the operation device 70, the display device 80, and the like.

The controller 90 is connected to the operation device 70 and the display device 80. The operation device 70 receives an input operation of a user, and outputs a signal corresponding to the input operation to the controller 90. The display device 80 displays a display screen corresponding to an input operation in the operation device 70 under the control of the controller 90.

The display screen is used for setting of the injection molding machine, and the like. The display screen is provided in plural numbers and is displayed in a switched manner or is displayed in an overlapping manner. The user operates the operation device 70 while viewing the display screen displayed by the display device 80, thereby setting the injection molding machine (including inputting the set value).

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

The mold clamping device 10 performs mold closing, pressure increasing, mold clamping, pressure releasing, and mold opening of the mold device 30. The mold clamping device 10 includes a fixed platen 12, a movable platen 13, a toggle base 15, a tie bar 16, a toggle mechanism 20, and a mold clamping motor 21. Hereinafter, the moving direction of the movable platen 13 at the time of mold closing (rightward direction in fig. 1 and 2) will be described as the front, and the moving direction of the movable platen 13 at the time of mold opening (leftward direction in fig. 1 and 2) will be described as the rear.

The fixed platen 12 is relatively fixed to the frame Fr. A stationary mold 32 is mounted on a surface of the stationary platen 12 opposed to the movable platen 13.

The movable platen 13 is movable along a guide (e.g., rail) 17 laid on the frame Fr, and is movable in and out relative to the fixed platen 12. The movable mold 33 is mounted on a surface of the movable platen 13 facing the fixed platen 12.

By advancing and retreating the movable platen 13 relative to the fixed platen 12, mold closing, and mold opening are performed. The mold device 30 is composed of a fixed mold 32 and a movable mold 33.

The toggle seat 15 is connected to the fixed platen 12 with a gap therebetween, and is mounted on the frame Fr so as to be movable in the mold opening/closing direction. The toggle seat 15 may be movable along a guide laid on the frame Fr. The guides of the toggle rest 15 may also be identical to the guides 17 of the movable platen 13.

In the present embodiment, the fixed platen 12 is relatively fixed to the frame Fr, and the toggle seat 15 is movable in the mold opening and closing direction with respect to the frame Fr, but the toggle seat 15 may be relatively fixed to the frame Fr, and the fixed platen 12 is movable in the mold opening and closing direction with respect to the frame Fr.

The connecting rod 16 connects the fixed platen 12 and the toggle seat 15 with a space therebetween. The connecting rod 16 is provided with a plurality of connecting rods. The tie bars 16 extend in parallel with the mold opening and closing direction and according to the mold clamping force.

The toggle mechanism 20 is disposed between the movable platen 13 and the toggle seat 15. The toggle mechanism 20 is constituted by 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 base 15. These links 20b and 20c are connected to each other by pins or the like so as to be freely bendable. By advancing and retreating the crosshead 20a, the plurality of links 20b and 20c are bent and extended, and the movable platen 13 advances and retreats with respect to the toggle seat 15.

The clamp motor 21 is mounted to the toggle base 15. The clamp motor 21 advances and retreats the movable platen 13 by advancing and retreating the crosshead 20 a. A motion conversion mechanism for converting the rotational motion of the clamp motor 21 into a linear motion and transmitting the linear motion to the crosshead 20a is provided between the clamp motor 21 and the crosshead 20 a. The motion conversion mechanism is constituted by, for example, a ball screw mechanism.

The mold clamping device 10 performs a mold closing process, a pressure increasing process, a mold clamping process, a pressure releasing process, a mold opening process, and the like under the control of the controller 90. The injection molding machine repeatedly performs the metering step, the mold closing step, the pressure increasing step, the mold closing step, the filling step, the pressure maintaining step, the cooling step, the pressure releasing step, the mold opening step, the ejection step, and the like under the control of the controller 90, thereby repeatedly manufacturing the 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 referred to as "injection" or "molding cycle". The time required for 1 shot is also referred to as "molding cycle time" or "cycle time".

The one-shot molding cycle includes, for example, a metering step, a mold closing step, a pressure increasing step, a mold closing step, a filling step, a pressure maintaining step, a cooling step, a pressure releasing step, a mold opening step, and an ejection step in this order. The sequence here is the sequence in which the respective steps are started. The filling step, the pressure maintaining step, and the cooling step are performed during the mold clamping step. The end of the decompression step corresponds to the start of the mold opening step.

In the metering step, a metering motor of an injection device, not shown, is driven to rotate a screw of the injection device, not shown, at a set rotational speed, and the molding material is conveyed forward along a helical groove of the screw. With this, the molding material is gradually melted. As the molding material in a liquid state is conveyed to the front of the screw and accumulated in the front of a cylinder of an injection device, not shown, the screw is retracted.

In the mold closing step, the movable platen 13 is advanced by driving the mold clamping motor 21 to advance the crosshead 20a to the mold closing end position at a set movement speed, and the movable mold 33 is brought into contact with the fixed mold 32.

In the pressure increasing step, the clamping motor 21 is further driven to further advance the crosshead 20a from the die closing end position to the clamping position, thereby generating clamping force. When the mold is closed, a cavity space, not shown, is formed between the movable mold 33 and the fixed mold 32.

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

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

In the pressure maintaining step, an injection motor of an injection device, not shown, is driven to press the screw of the injection device forward, the pressure of the molding material at the tip portion of the screw (hereinafter, also referred to as "holding pressure") is held at a set pressure, and the molding material remaining in the cylinder of the injection device is pushed toward the mold device 30. An insufficient amount of molding material due to cooling shrinkage in the mold device 30 can be replenished. The filling step and the pressure maintaining step are collectively referred to as an injection step.

After the pressure maintaining process, a cooling process is started. In the cooling step, solidification of the molding material in the cavity space is performed. The metering step may be performed in the cooling step in order to shorten the molding cycle time.

In the decompression step, the clamping motor 21 is driven to retract the crosshead 20a from the clamping position to the mold opening start position, thereby retracting the movable platen 13 to reduce the clamping force. The mold opening start position and the mold closing end position may be the same position.

In the mold opening step, the mold clamping motor 21 is driven to retract the crosshead 20a from the mold opening start position to the mold opening end position at a set movement speed, thereby retracting the movable platen 13 and separating the movable mold 33 from the fixed mold 32.

In the ejection step, the ejector rod of the ejector device, not shown, is advanced from the standby position to the ejection position at a set movement speed, and thereby the movable member, not shown, of the mold device 30 is advanced to eject the molded article. Then, the ejector rod is retracted at a set movement speed, and the movable member is retracted to the original standby position.

When the thickness of the mold device 30 changes due to replacement of the mold device 30, temperature change of the mold device 30, or the like, the mold thickness is adjusted so that a predetermined clamping force is obtained at the time of clamping. In the die thickness adjustment, for example, the distance L between the fixed platen 12 and the toggle base 15 is adjusted so that the link angle of the toggle mechanism 20 becomes a predetermined angle at the time of the contact of the movable die 33 with the fixed die 32.

The mold clamping device 10 has a mold thickness adjusting mechanism 22. The die thickness adjusting mechanism 22 adjusts the die thickness by adjusting the distance L between the fixed platen 12 and the toggle base 15. The timing of the mold thickness adjustment is performed, for example, from the end of the molding cycle to the start of the next molding cycle. The die thickness adjusting mechanism 22 includes, for example, a screw shaft 22a formed at the rear end portion of the connecting rod 16, a screw nut 22b rotatably and non-advance/retreat held by the toggle seat 15, and a die thickness adjusting motor 22c for rotating the screw nut 22b screwed with the screw shaft 22 a.

A screw shaft 22a and a screw nut 22b are provided for each connecting rod 16. The rotational driving force of the die thickness adjusting motor 22c can be transmitted to the plurality of lead screw nuts 22b via the rotational driving force transmitting portion 22 e. The plurality of lead screw nuts 22b can be rotated synchronously. Further, the plurality of lead screw nuts 22b may be individually rotated by changing the transmission path of the rotational driving force transmission unit 22 e.

The rotational driving force transmitting portion 22e is constituted by a gear or the like, for example. At this time, a driven gear is formed on the outer periphery of each screw nut 22b, a drive gear is attached to the output shaft of the die thickness adjusting motor 22c, and an intermediate gear engaged with the driven gears and the drive gear is rotatably held in the center portion of the toggle seat 15. The rotational driving force transmitting portion 22e may be formed of a belt, a pulley, or the like instead of a gear.

The operation of the die thickness adjustment mechanism 22 is controlled by a controller 90. The controller 90 drives the die thickness adjustment motor 22c to rotate the lead screw nut 22b. As a result, the position of the toggle link 15 with respect to the connecting rod 16 is adjusted, and the interval L between the fixed platen 12 and the toggle link 15 is adjusted. In addition, a plurality of die thickness adjusting mechanisms may be used in combination.

The interval L is detected using the die thickness adjustment motor encoder 22 d. The thickness adjustment motor encoder 22d detects the rotation amount and rotation direction of the thickness adjustment motor 22c, and sends a signal indicating the detection result to the controller 90. The detection result of the die thickness adjustment motor encoder 22d is used for monitoring and controlling the position and the interval L of the toggle seat 15. The toggle seat position detector for detecting the position of the toggle seat 15 and the interval detector for detecting the interval L are not limited to the die thickness adjusting motor encoder 22d, and a conventional detector may be used.

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

Fig. 3 is a diagram showing a positional relationship of a connecting rod of an injection molding machine according to an embodiment, and is a diagram in which a fixed platen is viewed from a movable platen side. The injection molding machine has 4 connecting rods 16. The 4 tie bars 16 are arranged so as to be vertically symmetrical about the horizontal line L1 and so as to be laterally symmetrical about the plumb line L2 when viewed in the mold opening/closing direction. The upper side of the horizontal line L1 is referred to as the top surface side, and the lower side of the horizontal line L1 is referred to as the ground surface side. The side of the operating device 70 that is closer to the plumb line L2 is referred to as the operating side, and the side that is opposite to the operating device 70 that is closer to the plumb line L2 is referred to as the operating side opposite side.

The mold clamping force is applied to 4 tie bars 16, and each tie bar 16 is extended. The force against the extension of each connecting rod 16 is referred to as the axial force. When there is a difference in the effective lengths of the 4 connecting rods 16, the connecting rods 16 having a short effective length and the connecting rods 16 having a long effective length are different in axial force. Here, the effective length of the tie bar 16 is the interval between the fixed platen 12 and the toggle seat 15, which are connected by the tie bar 16, and is measured, for example, in a state where the clamping force is not acting.

By adjusting the effective length of the connecting rod 16, the balance of the axial forces can be adjusted. The balance of the axial forces is set so that the surface pressures of the fixed mold 32 and the movable mold 33 become target distributions at the time of mold clamping, for example. The target distribution may be either a uniform distribution or a non-uniform distribution, and is set according to the situation. Poor molding can be reduced.

The connection rod 16 is formed of a metal material, and thus the effective length of the connection rod 16 varies according to the temperature of the connection rod 16. The higher the temperature of the connecting rod 16, the longer the effective length of the connecting rod 16. By adjusting the temperature of the connecting rod 16, the effective length of the connecting rod 16 can be adjusted, and the balance of the axial forces can be adjusted.

Therefore, as shown in fig. 1 and 2, a heater 25, a temperature detector 27, an axial force detector 28, and the like are mounted to each of the connection rods 16. The heater 25, the temperature detector 27, the axial force detector 28, and the like are provided in the mold clamping device 10.

To adjust the effective length of the connecting rod 16, the heater 25 heats the connecting rod 16. The portion of the connecting rod 16 heated by the heater 25 is referred to as a heating portion. The heater 25 is constituted by an electric heater such as a heater, for example. The heater 25 is not limited to the electric heater, and may be constituted by a warm water jacket, for example.

The temperature detector 27 detects the temperature of the connecting rod 16 heated by the heater 25 and cooled by natural cooling. For example, the temperature detector 27 is disposed in the vicinity of the heater 25, and detects the temperature of the heating portion of the connection rod. The temperature detector 27 outputs the detection result to the controller 90.

The controller 90 controls the heater 25 so that the actual value of the temperature of the heating portion of the connecting rod 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 connecting rod 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 connecting rod 16 by detecting the strain of the connecting rod 16.

The axial force detector 28 of the above embodiment is of a strain gauge type, but may be of a piezoelectric type, a capacitance 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 connecting rod 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 the embodiment, when the temperature of the connecting rod 16 is raised, the heater 25 is operated to raise the temperature. On the other hand, when the temperature of the connecting rod 16 is lowered, the heater 25 is stopped, and the temperature is lowered by natural cooling (natural heat radiation and heat conduction to other components). In this way, the temperature of the connecting rod 16 can be changed only by "on"/"off" of the heater 25, and thus control can be prevented from becoming discontinuous, and deterioration in controllability can be prevented.

However, the response speed at the time of lowering the temperature of the connecting rod 16 becomes slower than the response speed at the time of raising the temperature due to this structure. When the temperature of the connecting rod 16 is lowered, the temperature cannot be lowered 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. 4. Fig. 4 is a block diagram showing an example of axial force control of the injection molding machine according to the embodiment.

The axial force command unit 910 is provided to the controller 90, for example. The axial force command unit 910 issues an axial force command (axial force set value) for each connecting rod 16 to the axial force control unit 920. Regarding the 4 connection bars 16 shown in fig. 3, the upper left is the 1 st connection bar, the lower left is the 2 nd connection bar, the upper right is the 3 rd connection bar, and the lower right is the 4 th connection bar. The operator inputs the axial force setting values of the 1 st to 4 th connecting rods to the controller 90 via the operation device 70. Thus, the axial force command unit 910 outputs the axial force set values Ncmd1, ncmd2, ncmd3, and Ncmd4 of the 1 st, 2 nd, 3 rd, and 4 th connecting rods as axial force commands to the axial force control unit 920.

The axial force control unit 920 is provided to the controller 90, for example. The axial force control unit 920 controls the heater 25 based on the axial force set values (Ncmd 1 to Ncmd 4) of the axial force command unit 910 and the axial force detection values (Nfb 1 to Nfb4 described later) detected by the axial force detector 28, thereby controlling the temperature of the connecting rod 16.

The axial force control unit 920 includes a temperature command generation unit 921, a current command generation unit 922, a temperature calculation unit 923, an axial force calculation unit 924, arithmetic units 925 and 926, and a correction calculation unit 927.

The arithmetic unit 925 receives the axial force set values (Ncmd 1 to Ncmd 4) of the respective connecting rods 16 from the axial force command unit 910, and receives the axial force detection values (Nfb 1 to Nfb 4) of the respective connecting rods 16 from an axial force calculation unit 924 described later, and outputs differences (Ncmd 1 to Nfb1,..once.) and Ncmd4 to Nfb 4) between the axial force set values and the axial force detection values of the respective connecting rods 16.

The temperature command generating unit 921 calculates the temperature change amount of each link 16 based on the output value of the arithmetic unit 925 so that the deviation between the set axial force value and the detected axial force value becomes smaller (deviation reducing process). For example, the temperature command generating unit 921 has a data table indicating a relationship between the temperature rise and the axial force rise of the connecting rod 16. The data table is configured to reduce the axial force as the temperature of the connecting rod 16 increases. The temperature command generating unit 921 calculates the temperature change amount of each connecting rod 16 using the difference between the axial force set value and the axial force detection value, for example, from a data table. That is, when the detected axial force value is lower than the set axial force value, the temperature change amount for lowering the temperature of the connecting rod 16 is calculated. On the other hand, when the detected axial force value is higher than the set value Yu Zhouli, the temperature change amount for raising the temperature of the connecting rod 16 is calculated.

The temperature command generating unit 921 generates a new target temperature for each link 16 based on the temperature change amount of each link 16 and the current target temperature for each link 16. The temperature command generating unit 921 outputs the generated target temperatures (target temperatures Tcmd1 and Tcmd2 of the 1 st and 2 nd and 3 rd and 4 th connecting rods, tcmd3 and Tcmd4 of the 4 th connecting rod) to the arithmetic unit 926 as temperature commands.

The arithmetic unit 926 receives the target temperatures (Tcmd 1 to Tcmd 4) of the respective connection rods 16 from the temperature command generating unit 921, and receives the temperature detection values (Tfb 1 to Tfb 4) of the respective connection rods 16 from the temperature calculating unit 923, which will be described later, and outputs differences (Tcmd 1 to Tfb1, and.+ -. And Tcmd4 to Tfb 4) between the target temperatures and the temperature detection values of the respective connection rods 16.

The current command generating unit 922 outputs a control signal to the relay 25b corresponding to the heater 25 of each link 16 based on the output value of the arithmetic unit 926 so as to reduce the deviation between the target temperature and the temperature detection value. The relay 25b controls the supply of electric power from the heater power supply 25a to the heater 25 in response to a control signal from the current command generating unit 922. Here, when the temperature detection value is higher than the target temperature, the current command generating section 922 outputs a control signal to turn "off" the heater 25. When the temperature detection value is lower than the target temperature, the current command generating unit 922 outputs a control signal to turn "on" the 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 temperature detection value. The connection rod 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 connecting rod 16 based on the detection signal of the temperature detector 27. The temperature detectors 27 are provided to the respective connection rods 16. The calculated temperatures of the connecting rods 16 (the temperature detection value Tfb1 of the 1 st connecting rod, the temperature detection value Tfb2 of the 2 nd connecting rod, the temperature detection value Tfb3 of the 3 rd connecting rod, and the temperature detection value Tfb4 of the 4 th connecting rod) are output to the arithmetic unit 926.

The axial force calculation unit 924 calculates the axial force of the connecting rod 16 based on the detection signal of the axial force detector 28. Further, the axial force detectors 28 are provided to the respective connection rods 16. The calculated axial forces of the connecting rod 16 (the axial force detection values Nfb1 and Nfb2 of the 1 st connecting rod and the axial force detection values Nfb3 and Nfb4 of the 3 rd connecting rod and the 4 th connecting rod) are outputted to the arithmetic unit 925.

The correction operation unit 927 receives the differences (Tcmd 1 to Tfb1, & gt, tcmd4 to Tfb 4) between the target temperatures of the respective connection rods 16 outputted from the operation unit 926 and the temperature detection values. The correction operation unit 927 determines whether or not the link 16 whose commanded temperature is lowered is present among the 4 links 16. Here, the instruction to decrease the temperature is an instruction to decrease the temperature of the link 16, and refers to a case where the output from the arithmetic unit 926, that is, "target temperature-temperature detection value", is a negative value. The instruction to raise the temperature of the link 16 is an instruction to raise the temperature of the link 16, and is a case where the output from the arithmetic unit 926, that is, the "target temperature-temperature detection value" is a positive value.

When the connecting rod 16 whose commanded temperature is lowered is present, the correction operation unit 927 outputs a command to decrease the axial force set value to the axial force command unit 910. For example, the output shaft force offset Ns. The axial force offset amount Ns may be a predetermined value or may be a value that changes according to the temperature decrease amount (the difference between the target temperature and the temperature detection value) of the connecting rod 16 whose commanded temperature is decreased.

Upon receiving the command to decrease the axial force set value from the correction operation unit 927, the axial force command unit 910 decreases the axial force set value of each connecting rod 16. For example, if the shift amount of the axial force that decreases the axial force set value is Ns, the axial force set values Ncmd1-Ns of the 1 st connecting rod, ncmd2-Ns of the 2 nd connecting rod, ncmd3-Ns of the 3 rd connecting rod, and Ncmd4-Ns of the 4 th connecting rod are outputted as new axial force commands to the axial force control unit 920.

In this way, by reducing the set values of the axial forces of the respective connection rods 16, the target temperature generated by the temperature command generating unit 921 becomes high. For example, when the temperature shift amount corresponding to the axial force shift amount Ns is set to Ts, the temperature command generating unit 921 outputs the target temperature tcmd1+ts of the 1 st connecting rod, the target temperature tcmd2+ts of the 2 nd connecting rod, the target temperature tcmd3+ts of the 3 rd connecting rod, and the target temperature tcmd4+ts of the 4 th connecting rod as new temperature commands to the arithmetic unit 926.

Thereby, the temperature difference of the target temperatures of the 4 connection rods 16 can be maintained and the target temperature can be raised. Since the temperature difference of the target temperatures of the 4 connecting rods 16 can be maintained, the balance of the axial forces, for example, the axial force balance in the vertical direction (the relationship between the 1 st and 3 rd connecting rod groups and the 2 nd and 4 th connecting rod groups), the axial force balance in the horizontal direction (the relationship between the 1 st and 2 nd connecting rod groups and the 3 rd and 4 th connecting rod groups), and the axial force balance in the torsion direction (the relationship between the 1 st and 4 th connecting rod groups and the 2 nd and 3 rd connecting rod groups) can be adjusted.

Further, since the target temperature can be raised by the correction operation unit 927 for the connecting rod 16 whose temperature detection value becomes higher than the target temperature, the amount of temperature drop can be reduced, and the time required for natural cooling can be reduced, thereby improving the responsiveness. Further, when the axial force offset Ns of the correction operation unit 927 is increased, the temperature offset Ts is also increased, and the difference between the target temperature and the temperature detection value output from the operator 926 can be set to 0 or more in all the tie bars 16. Accordingly, the temperature of the connecting rod 16 is raised by the heater 25 having good responsiveness, and thus the axial force control can be performed, so that the responsiveness is further improved.

The correction operation unit 927 determines whether or not the temperature of the link 16 is to be lowered based on the output of the operation unit 926, but may determine whether or not the temperature of the link 16 is to be lowered based on the output of the operation unit 925. That is, when the "axial force set value-axial force detection value" output from the arithmetic unit 925 is positive, the correction arithmetic unit 927 determines that the temperature decrease instruction of the connecting rod 16 is issued, and decreases the axial force set value.

As described above, in the axial force control shown in fig. 4, the structure is shown in which the axial force set value is reduced in all the connecting rods 16 when the axial force set value is lower than the axial force set value in any one of the connecting rods 16 (when the temperature detected value of the connecting rod 16 is higher than the target temperature). The other axial force control will be described with reference to fig. 5 and 6.

Fig. 5 is a block diagram showing another example of axial force control of the injection molding machine according to the embodiment. In the axial force control shown in fig. 5, a structure is shown in which the axial force detection value is increased (shifted) in all the connecting rods 16 when the axial force detection value is lower than the axial force set value (when the temperature detection value of the connecting rod 16 is higher than the target temperature) in any one of the connecting rods 16.

The axial force control unit 920A includes a temperature command generation unit 921, a current command generation unit 922, a temperature calculation unit 923, an axial force calculation unit 924, arithmetic units 925A and 926, and a correction calculation unit 927A. The axial force control unit 920A shown in fig. 5 is different in configuration from the axial force control unit 920 shown in fig. 4 in the correction operation unit 927A and the operation unit 925A. Other structures are the same, and duplicate explanation is omitted.

The correction operation unit 927A receives the differences (Tcmd 1 to Tfb1, & gt, tcmd4 to Tfb 4) between the target temperatures of the respective connection rods 16 outputted from the operation unit 926 and the temperature detection values. The correction arithmetic unit 927A determines whether or not the link 16 whose temperature is lowered by the command is present among the 4 links 16. When the connecting rod 16 whose commanded temperature is lowered is present, the correction operation unit 927A outputs a command to increase (shift) the shaft force detection value. For example, the output shaft force offset Ns. The axial force offset amount Ns may be a predetermined value or may be a value that changes according to the temperature decrease amount (the difference between the target temperature and the temperature detection value) of the connecting rod 16 whose commanded temperature is decreased.

The arithmetic unit 925A receives the axial force set values (Ncmd 1 to Ncmd 4) of the connecting rods 16 from the axial force command unit 910, receives the axial force detection values (Nfb 1 to Nfb 4) of the connecting rods 16 from the axial force calculation unit 924, and receives the axial force offset Ns from the correction arithmetic unit 927A, thereby outputting the differences (Ncmd 1 to Nfb1 to Ns,..+ -. And Ncmd4 to Nfb4 to Ns) between the axial force set values of the connecting rods 16 and the offset axial force detection values.

According to this configuration, as in the case of the axial force control shown in fig. 4, the axial force balance can be adjusted and the responsiveness can be improved in the axial force control shown in fig. 5.

The correction operation unit 927A determines whether or not the temperature of the link 16 is to be decreased based on the output of the operation unit 926, but may determine whether or not the temperature of the link 16 is to be decreased based on the output of the operation unit 925A. That is, when the output from the arithmetic unit 925, that is, "the set value of the axial force-the detected value of the axial force" is positive, the correction arithmetic unit 927A may determine that the temperature of the connecting rod 16 is instructed to decrease and increase the detected value of the axial force.

Fig. 6 is a block diagram showing still another example of axial force control of the injection molding machine according to the embodiment. In the axial force control shown in fig. 6, a structure is shown in which the target temperature is increased (shifted) in all the connecting rods 16 when the axial force detection value is lower than the axial force set value (when the temperature detection value of the connecting rod 16 is higher than the target temperature) in any one of the connecting rods 16.

The axial force control unit 920B includes a temperature command generating unit 921, a current command generating unit 922, a temperature calculating unit 923, an axial force calculating unit 924, arithmetic units 925, 926, 928B, and a correction calculating unit 927B. The axial force control unit 920B shown in fig. 6 is different in configuration from the axial force control unit 920 shown in fig. 4 in the correction operation unit 927B and the operation unit 928B. Other structures are the same, and duplicate explanation is omitted.

The correction operation unit 927B receives the differences (Tcmd 1 to Tfb1, & gt, tcmd4 to Tfb 4) between the target temperatures of the respective connection rods 16 outputted from the operation unit 926 and the temperature detection values. The correction arithmetic unit 927B determines whether or not the link 16 whose temperature is lowered by the command is present among the 4 links 16. When the link 16 whose commanded temperature is lowered is present, the correction operation unit 927B outputs a command to increase the target temperature. For example, the temperature offset Ts is output. The temperature offset 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 connecting rod 16 that is instructed to be temperature-decreased.

The arithmetic unit 928B receives the target temperatures (Tcmd 1 to Tcmd 4) of the respective connecting rods 16 from the temperature command generating unit 921, the temperature shift amount Ts is input from a correction operation unit 927B described later, and new target temperatures (tcmd1+ts, &..once., tcmd4+ts) of the respective tie bars 16 are output. The new target temperature (tcmd1+ts, &..once.) and tcmd4+ts are input to the arithmetic unit 926.

According to this configuration, as in the case of the axial force control shown in fig. 4, the axial force balance can be adjusted and the responsiveness can be improved in the axial force control shown in fig. 6.

The correction operation unit 927B determines whether or not the temperature of the link 16 is to be decreased based on the output of the operation unit 926, but may determine whether or not the temperature of the link 16 is to be decreased based on the output of the operation unit 925. That is, when the output from the arithmetic unit 925, that is, the "axial force set value-axial force detection value" is positive, the correction arithmetic unit 927B may determine that the temperature lowering instruction of the connecting rod 16 is issued and raise the target temperature.

Fig. 7 is a graph showing an example of the temperature and clamping force of each tie bar at the time of controlling the axial force of the injection molding machine according to the embodiment. In the upper graph, the horizontal axis is the number of shots, the vertical axis is the temperature, T1 is the temperature of the 1 st connecting rod, T2 is the temperature of the 2 nd connecting rod, T3 is the temperature of the 3 rd connecting rod, and T4 is the temperature of the 4 th connecting rod. In the lower graph, the horizontal axis is the number of shots, and the vertical axis is the detection value of the mold clamping force at the time of mold clamping. The vertical axis may be an average value of the detection values of the clamping force in the clamping step. The vertical axis may be set to the maximum value of the clamping force in the clamping step. The clamping force is the sum of the axial forces of the 1 st to 4 th tie bars (nfb1+nfb2+nfb3+nfb4). That is, the axial force detector 28 also serves as a mold clamping force detector for detecting a mold clamping force.

The axial force control (control "on") of the injection molding machine according to the first embodiment is started. As shown in the graph of the above section, the axial force control is performed so as to heat the connecting rod 16 or maintain the temperature. In the example shown in fig. 7, the temperature T1 of the 1 st connecting rod is maintained and the temperatures T2 to T4 of the 2 nd to 4 th connecting rods are raised. Thus, the balance of the axial force is adjusted, and the responsiveness of the axial force control is improved.

However, the instruction to lower the temperature of the connecting rod 16 is set to reduce the amount of temperature drop or raise the temperature by raising the target temperature. In general, the lowering of the axial force of the connecting rod 16 sets the instruction to lower the temperature to reduce the amount of lowering thereof, or to raise the temperature by an amount. That is, the axial force is reduced by an amount corresponding to the temperature shift amount. As shown in the chart of the following section, the actual value of the mold clamping force decreases. When the actual value of the clamping force is smaller than the set value by a predetermined value or more, the controller 90 controls the die thickness adjusting mechanism 22 to narrow the interval L so that the actual value of the clamping force approaches the set value, in other words, the position of the toggle seat 15 is advanced to the side of the fixed platen 12. This enables recovery of a desired clamping force (clamping force correction). The timing of the mold clamping force correction is performed, for example, from the end of the molding cycle to the start of the next molding cycle.

In the example shown in fig. 7, the axial force command is changed in the middle of the axial force control (command change). In the example shown in fig. 7, the temperature T2 of the 2 nd connecting rod is maintained, and the temperatures T1, T3, T4 of the 1 st, 3 th, 4 th connecting rod are raised.

When the difference between the detected axial force value and the set axial force value falls within the predetermined range, the correction calculation unit 927 maintains the relative temperature difference between the 4 connecting rods 16 and reduces the temperature of the connecting rods 16, as shown in fig. 7. This can maintain the balance of the axial force and reduce the temperature of the connecting rod 16. Further, the axial force of each tie bar 16 increases due to the temperature decrease of the tie bar 16, and the mold clamping force can be recovered.

Although not shown, the correction operation unit 927 may control to reduce the target temperature when the temperature of the connecting rod 16 is equal to or higher than the predetermined 1 st threshold temperature. This can prevent the temperature of the connecting rod 16 from becoming excessively high. At this time, the relative temperature difference of the 4 connection bars 16 is maintained, and the temperature of the connection bars 16 is lowered. This can maintain the balance of the axial force and reduce the temperature of the connecting rod 16. When the temperature of the connecting rod 16 is equal to or lower than the predetermined 2 nd threshold temperature, the axial force control described above may be restarted.

While the embodiments and the like of the injection molding machine have been described above, the present application is not limited to the embodiments and the like, and various modifications and improvements can be made within the gist of the present application described in the claims.

The injection molding machine may be provided with a heating range limiting mechanism that limits the heating range of the connecting rod 16 heated by the heater 25. The heating range limiting mechanism is constituted by, for example, coolers arranged on both sides of the connecting rod 16 in the axial direction via the heater 25. The cooler is constituted, for example, by a water-cooled jacket. The cooler is not limited to the water-cooled jacket, and may be constituted by a fin or the like, for example. The cooling method of the fin may be either a forced air cooling method or a natural air cooling method using a cooling fan. The heating range limiting mechanism can limit the movement of heat applied to the tie bar 16 by the heater 25, so that the time required for the temperature of the entire mold clamping device 10 to stabilize can be shortened, and the time required for the balance of the axial force to stabilize can be shortened. Further, the thermal expansion range of the connecting rod 16 can be managed, the amount of change in the effective length due to the temperature change of the connecting rod 16 can be managed with high accuracy, and the axial force can be adjusted with high accuracy. The heating range limiting mechanism is not limited to a cooler, and may be any structure as long as it can limit movement of heat. That is, heat insulation may be provided between the heating range and the outside of the heating range.

The controller 90 controls the cooler in such a manner as to limit the heating range of the connecting rod 16. At this time, the controller 90 may control the cooler so that the actual value of the temperature of the cooling portion of the connecting rod 16 becomes a set value. The temperature of the cooling portion of the connecting rod 16 is detected by a temperature detector different from the temperature detector 27. The temperature detector is disposed in the vicinity of the cooler. The controller 90 performs temperature control by the heater 25 in a state where the heating range limiting mechanism is operated. That is, temperature control by the heating range limiting mechanism and the heater 25 is performed simultaneously.

The injection molding machine according to the embodiment has been described as an example in which the axial force detectors 28 are provided in each of the 4 connecting rods, but the application is not limited thereto. The connecting rods 16 may be disposed at least above and below the die device 30 and/or the connecting rods 16 may be disposed on the left and right sides of the die device 30. By providing the axial force detectors 28 in the connecting rods 16 disposed above and below the die device 30, respectively, the balance of the axial forces in the vertical direction can be adjusted. By providing the axial force detectors 28 in the connecting rods 16 disposed on the left and right sides of the die device 30, respectively, the balance of the axial force in the horizontal direction can be adjusted. Also, the number of detectors can be reduced.

The injection molding machine according to the embodiment has been described with respect to an example in which the heater 25 controlled by the controller 90 is used to adjust the axial force of the connecting rod 16 not to stabilize the temperature but to heat the connecting rod 16. That is, instead of the heater 25, a cooler controlled by the controller 90 may be provided, and the axial force of the connecting rod 16 may be adjusted in a direction of cooling the connecting rod 16 instead of stabilizing the temperature.

Here, in the injection molding machine provided with a cooler in place of the heater 25, when the temperature of the connecting rod 16 is reduced, the temperature is reduced by operating the cooler. On the other hand, when the temperature of the connecting rod 16 is raised, the temperature is raised by stopping the cooler. In this way, the temperature of the connecting rod 16 can be changed only by "on"/"off" of the cooler, and thus control discontinuity can be prevented, thereby preventing deterioration of the controllability.

However, the response speed at the time of raising the temperature of the connecting rod 16 becomes slower than the response speed at the time of lowering the temperature due to this structure. When the temperature of the connecting rod 16 is raised, the temperature cannot be raised to a predetermined temperature or higher (for example, an atmospheric temperature).

At this time, when any one of the connection rods 16 has a connection rod 16 whose temperature has been instructed to rise, the correction operation unit increases the axial force set value in all the connection rods 16. In addition, when any one of the connection rods 16 has a connection rod 16 whose temperature has been instructed to rise, the correction operation unit may reduce the axial force detection value in all the connection rods 16. When any one of the connection rods 16 has a connection rod 16 whose commanded temperature has risen, the correction calculation unit may lower the target temperature in all the connection rods 16.

Thus, since the target temperature can be reduced by the correction operation unit for the connecting rod 16 whose temperature detection value becomes lower than the target temperature, the amount of temperature rise can be reduced, and the balance of the axial force can be maintained, and the responsiveness can be improved.

The present application claims priority based on japanese patent application No. 2018-158629 of the japanese application, 8-27, the entire contents of which are incorporated herein by reference.

Symbol description

10-mold clamping device, 16-connecting rod, 22-mold thickness adjusting mechanism, 25-heater, 27-temperature detector, 28-axial force detector, 90-controller, 910-axial force command unit, 920A, 920B-axial force control unit, 921-temperature command generation unit (axial force control command generation unit), 922-current command generation unit, 923-temperature calculation unit, 924-axial force calculation unit, 925A, 926, 928B-arithmetic unit, 927A, 927B-correction arithmetic unit (axial force control command generation unit).

Claims

1. An injection molding machine, comprising:

A link lever axial force adjusting device for adjusting the axial force of the plurality of link levers, wherein in the injection molding machine,

the connecting rod shaft force adjustment device includes:

an axial force detector that detects axial forces of the plurality of connection rods, a balance of the axial forces of the plurality of connection rods, or a balance of forces pressing the mold; a kind of electronic device with high-pressure air-conditioning system

An axial force control part for controlling the temperature of the connecting rod according to the detection value and the set value,

the axial force control unit generates a control command to raise the temperature of one of the plurality of connection rods when it is detected that the axial force of the one of the plurality of connection rods is higher than a set value, and reduces the amount of decrease in the temperature of the one connection rod by changing the set value of the plurality of connection rods to reduce the axial force when it is detected that the axial force of the one of the plurality of connection rods is lower than the set value.