JPH02258216A - Method and apparatus for controlling toggle type mold clamping device - Google Patents

Abstract

PURPOSE:To automate the mold opening/closing process by a method wherein the changing-over of fluid pressure is performed at optimum timing by means of a controlling device on the judgement of the coincidence of the change of the distance between a mold clamping housing and a movable mold detected with a sensor with a reference value. CONSTITUTION:Since a scale 10 is fixed to a mold clamping housing 1 and a position marker 11 is fixed to a movable mold 2, the distance between the mold clamping housing 1 and the movable mold 2, which changes through the extension of toggle links or the elongation of tie bars 6, is detected with an image sensor 12 in order to detect the distance through the conversion to electric signal. In order to control mold clamping on the basis of the electric signal sent from said distance detecting means, a circuit 20 to detect the generation of mold clamping force, a circuit 21 to detect the mold touching state and a controlling device 16 are provided. A valve changing-over device 18 changes over a fluid pressure changing-over valve 19 upon receipt of a control signal VC sent from the controlling device 16 so as to change over from low pressure fluid to high pressure fluid at the timing for generating mold clamping force in order to extend tie bars 6, resulting in generating the desired mold clamping force.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mold clamping device in a toggle injection molding machine and a control method thereof.

[Prior Art] A mold clamping device for a toggle injection molding machine is a device that uses a toggle mechanism to amplify the force generated by a hydraulic cylinder or other power source to obtain a large mold clamping force.

To briefly explain the mold clamping mechanism, the movable mold moves forward due to the force generated by the power source, the toggle link extends, the mold closes slightly before the closing position, and the mold is touched, and then the movable mold moves forward due to the force generated by the power source. With the toggle link fully extended,
This causes the tie bar to extend, and the mold is clamped by the elastic force generated by the extension of the tie bar, creating a mold clamping force generation state.

The mold clamping force is determined by the amount of extension of the tie bar, that is, the amount of backward extension of the tie bar from the mold touching state to the mold clamping force generation state. Accurate detection is important.

Further, after the touch position is detected, it is important to fully extend the toggle link to generate a predetermined mold clamping force, and to enable the operator to clearly recognize the generation of the mold clamping force.

FIGS. 6(a) and 6(b) are cross-sectional views of a conventional example of a mold clamping device in a toggle injection molding machine, and FIG. 6(a) is a cross-sectional view at the mold touch position, and FIG. is a sectional view in a state where mold clamping force is generated.

In this conventional example, the mold touch position is mechanically detected using the cam 25 and the limit switch LSI, and the generation of mold clamping force is similarly detected mechanically using the cam 25a and the limit switch LS2. .

To adjust the cam and limit switch positions, first, after installing the mold, the operator detects the zero point position of the mold thickness (the position where the two molds that were open have narrowed and come into contact), and then a drive mechanism (not shown) adjusts each position. After the tie bar nut 26a is rotated synchronously to move the mold clamping housing 21 slightly in the direction of the movable platen 23 and the mold clamping force is set, the 0th order adjusts the cam 25 for mold touch detection or the limit switch LSI. , determine the mold clamping confirmation position, and install the limit switch LS2 at this position. This position is determined by taking into consideration the extension of the tie bars 26 or the position of the mold clamping housing 21 after the mold clamping force is generated, and calculating the amount of movement of the crosshead corresponding to the desired mold clamping force.

[Problem to be solved by the invention] The conventional technology shown in FIGS. 6(a) and 6(b) above has the following problems:
Each time the mold is replaced, the limit switch installation position must be changed manually, making adjustment cumbersome.

Additionally, the position of the limit switch's striking point will be shifted by the amount of offset between the going side and the returning side, so care must be taken when adjusting it so that it is always struck on the going side.
In this respect as well, adjustment is troublesome.

Furthermore, the detection position by manual operation may not match the actual mold touch position, and there is a limit to the improvement of detection accuracy.

[Means for Solving the Problems] A control method for a toggle type mold clamping device of the present invention provides a method for controlling a toggle type mold clamping device by providing a force generated by a power source such as a hydraulic cylinder of the toggle type mold clamping device between a mold clamping housing and a movable platen. The movable mold attached to the movable plate is clamped by bringing the movable mold attached to the movable plate into close contact with the fixed mold attached to the fixed plate. This is a method for automatically controlling the operation of a toggle-type mold clamping device. First, a movable type and a fixed type are attached to a movable platen and a fixed platen, respectively, and the toggle link is fully extended, and the mold clamping housing and the movable platen are fully extended. moving the mold clamping housing forward while automatically detecting the distance between the housing and the housing using a distance detection means;
A detection value of the distance detecting means at the mold zero point position where the movable mold and the fixed mold are in contact with each other when the toggle link is fully extended is set as a first reference value, and further, the mold clamping housing is pushed in by a predetermined amount. the detected value of the distance detecting means at the mold touch position where the toggle link is bent is set as a second reference value, and then, at the time of actual mold clamping, the detected value of the distance detecting means and the second While comparing with the reference value using the mold touch state detection means, from the mold open state,
The force generated by the power source presses the movable platen to move it forward, and when it is detected that the detection value of the distance detection means matches the second reference value, the force generated by the power source is switched. The method is characterized in that the mold clamping force is switched and increased using a means to press the movable platen more strongly to stretch the bent toggle link and generate a desired mold clamping force.

Furthermore, the generation of mold clamping force is detected by determining whether the detection value of the distance detection means matches the first reference value using the mold clamping force generation detection means, and the recognition means such as an indicator light is activated. It's good to let them do it.

Furthermore, the control device for the toggle type mold clamping device of the present invention magnifies the force generated by a power source such as a hydraulic cylinder using a toggle link provided between the mold clamping housing and the movable platen, and In a toggle type mold clamping device that presses the movable platen with force and clamps the movable mold attached to the movable platen in close contact with the fixed die attached to the fixed platen, the mold clamping housing and the movable platen A distance detection means that automatically detects the distance between the two and a mold touch state is determined by comparing the detection value of the distance detection means and a preset second reference value to determine a match. a mold touch state detection means for detecting the presence of the mold touch state and transmitting a mold touch detection signal; a switching means for switching the strength of the force generated by the power source; and a mold touch state detection means sent from the mold touch state detection means. Upon receiving the detection signal, a control device instructs the switching means to switch the force generated by the power source to generate mold clamping force; and after switching the force generated by the power source, the detection value of the distance detection means is Mold clamping force generation that detects that it matches the first reference value, thereby detecting a transition from a mold touching state to a state in which stable mold clamping force is generated, and sends a detection signal to the control device. It is characterized by comprising a detection means.

[Function] By using a sensor to detect the change in the distance between the mold clamping housing and the movable mold and determining whether it matches the reference value, the mold position (state) is electrically detected and the control device is used to detect the change in the distance between the mold clamping housing and the movable mold. The fluid pressure is switched at the optimal timing to automate the mold opening and closing process.

[Example] Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the overall configuration of an embodiment of the present invention.

The mold clamping body has the conventional basic configuration, namely, a mold clamping housing 1, a movable platen 2, a fixed platen 3, a toggle link 4, a piston rod 5, a tie bar 6, a tie bar nut 6a, a piston 7, a movable die 8, and a fixed die 9. It has a structure in which a scale 10 and a position marker 11 are newly added to the basic configuration consisting of the following.

In this embodiment, the distance detection means is configured as follows.

Since the scale 10 is fixed to the mold clamping housing l and the position marker 11 is fixed to the movable platen 2, when the toggle link 4 is extended or the tie bar 6 is extended during mold clamping, the mold clamping housing 1 and The distance to the movable platen 2 changes. Therefore, the distance is detected by detecting this distance with the image sensor 12 and converting it into an electrical signal.

In this embodiment, the mold clamping control is performed by the electric signal of the distance detecting means, and in order to perform this electrical processing, a mold clamping force generation detection circuit 20, which is the mold clamping force generation detection means, is used.
．． A mold touch state detection circuit 21 serving as a mold touch state detection means, a control device 16, a CRT 14, a mold clamping force generation indicator light 17, and a tie bar nut drive mechanism 30 are provided.

Further, an input device 15 is provided for inputting various conditions. Further, switching means for switching the strength of the force generated by the power source includes a valve switching device 18 and a fluid pressure switching valve 1.
Consists of 9. The valve switching device 1 switches the fluid pressure switching valve 19 in response to the control signal vc sent from the control device 16 and sent through the line L2, and switches from low pressure fluid to high pressure fluid at the mold clamping force generation timing. to extend the tie bars 6 and generate a desired mold clamping force. Mold clamping force generation indicator light 1
7 is an example of a mold clamping recognition means, which is used to notify the operator that mold clamping force has been generated.

Next, the operation of this embodiment will be specifically explained.

The operation of this embodiment can be broadly divided into a reference value setting operation that specifies a reference value that is an indicator for detecting a mold touch state or a mold clamping force generation state, stores the specified reference value, and a subsequent actual operation. It is broadly divided into mold clamping (molding) operation.

Figures 2 (a) to (c) are cross-sectional views at each step during the reference value setting operation, and Figures 3 (a) to (c) are cross-sectional views at each step during the mold clamping operation. FIG. 4 is a diagram showing changes in the distance between the mold clamping housing 1 and the movable platen 2 for each step in FIG. 3, and FIG. 5(a).

(b) is a state diagram of the mold clamping device when touching the mold, respectively;
FIG. 3 is a state diagram of the mold clamping device when mold clamping force is generated.

(1) Reference value setting operation 2 a- First, the mold clamping device is opened to a depth greater than the thickness of the mold to be mounted, and the movable mold 8 and the fixed mold 9 are mounted on the movable platen 2 and the fixed platen 3, respectively.

Next, the pre-calculated push-in amount Σδ is inputted from the input device 15. This input push-in amount Σδ is sent to the control device 16.
The data is stored in the memory 31 inside the computer.

In this state, the piston 5 is moved toward the anti-mould housing side, and the movable platen 8 is in a so-called mold-opening state. The movable platen 2 is moved forward from this state, and the distance between the mold clamping housing l and the movable platen 2 at this time is expressed as follows:
The distance from the free end of the scale 10 to the position marker 11 is LO.

11] Advance command for movable platen 2 from mouth JL input device 15 (start signal)
Enter. Then, the valve control signal ve is output from the control device 16.
The tie bar nut control signal Vr is sent to the valve switching device 18 via line L2, and the tie bar nut control signal Vr is sent to the tie bar nut drive mechanism 30 via line L3. In response to this, the valve switching device 18 opens the fluid pressure switching valve 19, which had been in the closed state, to the low pressure side, whereby the low pressure fluid flows in to press the piston 7 and move it forward. As a result, the toggle link 4 is fully extended and the movable platen 2 moves forward. At the same time or immediately after
Each tie bar nut 6a rotates synchronously by the tie bar nut drive mechanism 30, moves the mold clamping housing l and the movable platen 2 forward without changing the distance between them (with the toggle link 4 fully extended), and moves the movable mold 8 to the fixed mold 9. Bring to a contact state (mold zero point state).

At this time, the distance from the free end of the scale 10 to the position marker 11, which represents the distance between the mold clamping housing l and the movable platen 2, is La. This distance La is the distance between the image sensor 12
The signal is converted into an electrical signal by the amplifier 13, the line L1, the input device 15, and the control device 16, and then digitally displayed on the CRT 14.

This display La is a first reference value, for example.

Store it in memory or store it in the memory 31.

11 The control device 16 controls the valve switching device 18 by the valve control signal VC.
First, the tie bar nut drive mechanism 30 is instructed by the tie bar nut control signal Vτ to synchronously rotate each tie bar nut 6a, and the mold clamping housing 1 is moved toward the movable platen. Push-in amount Σδ
(stored in memory 31). As a result, the toggle link 4 is bent again and the distance from the free end of the scale lO to the position marker 11 is L.
It becomes b. When this distance Lb is reached, the mold is in the touch state, and this distance Lb is the same as the above-mentioned La.
It is digitally displayed on the CRT 14 in the same way as in the case of . This display Lb is a second reference value, and is stored or stored in the memory 31, for example.

The first and second reference values La obtained in this way,
Lb is input, or data is automatically read from the memory 31, and then a set signal is input. Then, La
A voltage vI21 corresponding to the mold clamping force generation detection circuit 20 is output from the control device 16 and is supplied to the non-inverting terminal of the comparator AI constituting the mold clamping force generation detection circuit 20 via the line L4. , while the voltage Vj22 corresponding to Lb
(This is the reference voltage for determining the mold touch state) is the control device 1
6 and is supplied to the non-inverting terminal of the comparator A2 forming the mold touch state detection circuit 21 via the line L5. With this, the reference value has been set and preparations for actual mold clamping have been completed.

Ru.

Next, the mold clamping operation will be explained.

(2) Mold clamping operation 11 In this state, the movable platen 8 and the fixed platen 9 are not in contact with each other, and are in a so-called mold opening state. From this state, movable plate 2
If this operation is started at time 10, then the distance from the free end of the scale 10 to the position marker 11, which represents the distance between the mold clamping housing l and the movable platen 2, is LO. (Time 10 in Figure 4).

Next, the valve control signal vc from the control device 16 is sent to the valve switching device 1.
Sent on 8th. In response to this, the valve switching device 18 opens the low-pressure side of the fluid pressure switching valve 19 that was in the closed state, whereby low-pressure fluid flows in and presses and advances the piston 7, causing the movable platen 2 to advance. . As the movable platen 2 moves forward, the movable mold 8 comes into contact with the fixed mold 9, resulting in a mold touching state.

At this time, the distance from the free end of the scale 10 to the position marker 11, which represents the distance between the mold clamping housing 1 and the movable platen 2, is Lb.
A signal indicating the detection to 6 is sent out via line L7.

The detection operation in the mold touch state detection circuit 21 is performed as follows.

When the distance from the free end of the scale 10 to the position marker, which represents the distance between the mold clamping housing l and the movable platen 2, becomes Lb, the output of the comparator A2 changes from high level to low level (ground), and the resistance A current flows from the power supply to ground via R4 and diode D2. Then, the forward voltage of diode D2 turns on NPN transistor Q3,
Subsequently, the PNP transistor Q4 is turned on and a signal indicating mold touch detection is sent to the control device 16 via the line L7.
will be sent to.

- Upon receiving this detection signal, the control device 16 instructs the valve switching device 18 to switch the fluid pressure switching valve 19 using the valve control signal vc.
switch. As a result, the high-pressure fluid presses the piston 7 more strongly, the toggle link 4 fully extends, and the tie bar 6
expands, and mold clamping force is generated as a reaction force. Then,
The distance between the mold clamping housing 1 and the movable platen 2 becomes La (time t2 in FIG. 4), and the mold clamping force generation detection circuit 20 detects the mold clamping force by the same operation as the mold touch state detection circuit 21 described above. It detects that this has occurred and sends a signal notifying this detection to the control device 16 via line L6.

Upon receiving the detection signal from the mold clamping force generation detection circuit 20, the control device 16 turns on the mold clamping force generation indicator light 17 to clearly indicate to the surroundings that stable mold clamping force is being generated.

Here, the drive-in amount Σδ in the step of FIG. 2(C) will be explained in more detail using FIGS. 5(a) and 5(b).

When the mold is touched from the mold touching state in (a) of the same figure to the mold clamping force generation state of (b) in the same figure, each element of the mold clamping device is deflected δ1. δ2
．． δ3. δ4. δ5. δ6. A force due to δ7 is generated. The above-mentioned push-in amount Σδ is the sum of these, and the forces of each element are kept in balance, and a force acting on the mold is generated as a reaction force.

The reason why the high-pressure fluid is switched immediately after the mold is touched and the low-pressure fluid is used as the power source until then is to keep energy consumption low.

Furthermore, the present invention is not limited to the above-described embodiments; for example, the mounting parts of the scale lO and the position marker 11 may be reversed, and the position detector and scale may be mounted on the mold clamping housing and the crosshead. The same effect can be obtained.

[Effects of the Invention] According to the toggle injection molding machine control method and device of the present invention, the mold touch position can be automatically detected.
This eliminates the need for manual operation of the mold touch limit switch and mold touch position detection, and also eliminates the variation between the detection position caused by conventional manual operation and the actual mold touch position, which has the effect of streamlining the process.

Furthermore, the recognition means of the indicator light allows the operator to easily confirm the generation of mold clamping force.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the overall configuration of an embodiment of the present invention, FIGS. 2(a) to (C) are sectional views of each step in the reference value setting operation, and FIGS. 3(a) to (C) are sectional views for each process in the mold clamping operation, Figure 4 is a diagram showing changes in the distance between the mold clamping housing 1 and the movable platen 2 in each process in Figure 3, and Figures 5 (a) and (b).
6(a) and 6(b) are cross-sectional views of the conventional example, respectively.
(b) is a cross-sectional view in a mold touching state, and (b) is a cross-sectional view in a mold clamping force generation state. l... Mold clamping housing, 2... Movable plate, 3... Fixed plate, 4... Toggle link, 5... Piston rod, 6... Tie bar 7... Piston, 8... - Movable type, 9... Fixed type, 10... Scale, 11... Position marker, 12... Image sensor, 13... Amplifier, 14... CRT. 15... Input device, 16... Control device, 17... Indicator light, 18... Valve switching device, 9... Fluid pressure switching valve, O... Mold clamping force generation detection circuit, 1 ...Mold touch state detection circuit. Patent applicant: Japan Steel Works, Ltd.

Claims (1)

[Claims] 1. The toggle link (4) provided between the mold clamping housing (1) and the movable platen (2) absorbs the force generated by a power source such as a hydraulic cylinder of a toggle type mold clamping device. The expanded force is used to press the movable platen (2), and the movable mold (8) attached to the movable platen (2) is pressed against the fixed mold attached to the fixed platen (3). (9) A method of automatically controlling the operation of a toggle type mold clamping device that clamps the mold in close contact with the movable mold (8) and the fixed mold clamping device, respectively. The mold (9) is installed, the toggle link (4) is fully extended, and the distance between the mold clamping housing (1) and the movable platen (2) is measured by the distance detecting means (10, 11, 12).
, 13), the mold clamping housing (1) is advanced while automatically detecting the movable mold (8) and the fixed mold (9) in a state where the toggle link (4) is fully extended. The distance detection means (10, 11,
12, 13) as the first reference value, and furthermore, the mold clamping housing (1) is set to a predetermined push-in amount (Σ
δ), and the distance detecting means (10, 11, 1) at the mold touch position where the toggle link (4) is bent.
2, 13) as the second reference value, and then, during actual mold clamping, the detection value of the distance detection means (10, 11, 12, 13) and the second reference value are Mold touch state detection means (21
), the movable platen (2) is pressed and moved forward by the force generated by the power source from the mold open state, and the detected value of the distance detection means (10, 11, 12, 13) is When it is detected that the power source matches the reference value 2, the force generated by the power source is switched and increased using the switching means (18, 19), and the movable platen (2) is further pressed and bent. A method for controlling a toggle-type mold clamping device, characterized in that a desired mold clamping force is generated by extending a toggle link (4) that has been previously closed. 2. The generation of mold clamping force is detected by the distance detection means (10, 11,
12 and 13) by determining whether the detected value matches the first reference value using a mold clamping force generation detection means (20), and activating a recognition means (17) such as an indicator light. Item 1. A method for controlling a toggle type mold clamping device according to item 1. 3. The force generated by a power source such as a hydraulic cylinder is expanded using a toggle link (4) provided between the mold clamping housing (1) and the movable platen (2), and the expanded force is used to Press the movable platen (2) and move the movable mold (8) attached to the movable platen (2) to the fixed mold (8) attached to the fixed platen (3).
9), a toggle type mold clamping device that clamps the mold in close contact with the mold clamping device includes distance detection means (10, 11, 12, 13) that automatically detects the distance between the mold clamping housing (1) and the movable platen (2).
), and by comparing the detection value of the distance detection means (10, 11, 12, 13) with a preset second reference value and determining a match, it is determined that the mold has been touched. a mold touch state detection means (21) that detects the power source and sends a mold touch detection signal; and a switching means (1) that switches the strength of the force generated by the power source.
8, 19), and upon receiving the mold touch detection signal sent from the mold touch state detection means (21), the switching means (18, 1
9) to switch the force generated by the power source to generate mold clamping force; and after switching the force generated by the power source, the distance detection means (10, 11, 12, 13)
) is detected to match the first reference value, thereby detecting a transition from the mold touch state to a state in which stable mold clamping force is generated, and transmits the detection signal to the control device (
16) A toggle type mold clamping device characterized in that it has a mold clamping force generation detection means (20) that sends out a mold clamping force.