JPH07329B2 - Method for setting mold clamping force of toggle type mold clamping device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for setting a mold clamping force of a toggle type mold clamping device in an injection molding machine for automatically setting a mold clamping force according to a mold thickness.

[0002]

2. Description of the Related Art Generally, a mold clamping device of an injection molding machine applies a predetermined mold clamping force to a mold. In the case of a toggle type mold clamping device, the mold clamping force is proportional to the extension of the tie bar during mold clamping due to the characteristics of the toggle mechanism. For this reason, in the toggle type mold clamping device, after mounting the mold, the toggle mechanism is clamped with the toggle mechanism expanded to the maximum extent, and at this time, the tie bar is stretched on the tie bar so that the elongation becomes the set mold clamping force. The position of the entire toggle mechanism was adjusted according to the mold thickness.

Conventionally, such a method for setting the mold clamping force has been disclosed in Japanese Patent Publication No. Sho 61-35924 and Japanese Patent Laid-Open No. 1-275001.
It is known from Japanese Patent Publication No. 6 and the like. The former uses a mold clamping cylinder as a drive source for the toggle mechanism, and the latter uses a servomotor as the drive source, and the basic setting method is the same. In the latter case, a tie bar with a threaded portion is provided at the rear, and a movable plate and a pressure receiving plate (toggle receiving plate) for supporting the movable die are slidably mounted on the tie bar, and there is a space between the movable plate and the pressure receiving plate. A toggle mechanism is installed on the shaft, and a mold thickness adjusting nut that is driven to rotate by a general-purpose motor is screwed into the screw portion. The mold thickness adjusting nut is rotatably connected to the pressure receiving plate. Then, when setting the mold clamping force, with the output torque of the servo motor limited,
The servo motor and general-purpose motor are driven to make the mold touch at the position where the crosshead in the torque mechanism is retracted from the mold clamping force setting position, and after the mold touch is detected, it is driven by the toggle mechanism. If the crosshead reaches the mold clamping force setting position, the servomotor speed is controlled according to the drive speed of the general-purpose motor so that the forward speed of the board and the reverse speed of the entire toggle mechanism are approximately the same. Stop at the same time. As a result, the mold clamping force is set according to the mold thickness.

[0004]

However, the conventional mold clamping force setting method described above has the following problems. That is, the motor used as a drive source for moving the entire toggle mechanism to adjust the die thickness is for the purpose of merely adjusting the position, and is also unlikely to be overloaded and does not require position control. Therefore, a general-purpose motor that does not require position control is used. Therefore, if the general-purpose motor is stopped when the crosshead reaches the mold-clamping force setting position, the stop position will actually become unstable due to coasting based on the inertia of the general-purpose motor, and as a result, an accurate mold clamping force will not be obtained. There was a difficulty that could not be set.

The present invention solves the problems existing in the prior art as described above. Even if a general-purpose motor is used, a toggle type can always set an accurate mold clamping force according to the mold thickness. An object is to provide a method for setting a mold clamping force of a mold clamping device.

[0006]

The method for setting the mold clamping force of the toggle type mold clamping device according to the present invention is such that the general motor 2 causes the entire toggle mechanism 3 to retract, and at the same time, the toggle drive section 4 causes the crossing of the toggle mechanism 3. When the crosshead 5 reaches the mold clamping force setting position while maintaining the mold touch state by advancing the head 5 from the position before the mold clamping force setting position in the direction of expanding the toggle mechanism 3, the general-purpose motor 2 and the toggle When the drive unit 4 is stopped and the position of the entire toggle mechanism 3 is adjusted according to the mold thickness, the general-purpose motor 2 is stopped, and then the general-purpose motor 2 is preset in the direction in which the entire toggle mechanism 3 advances. It is characterized in that it is operated for a predetermined correction time Ts. In this case, the correction time Ts is set to at least a time at which coasting after the stop of the general-purpose motor 2 can be offset. Note that it is desirable to operate the general-purpose motor 2 for the correction time Ts after the preset predetermined interval time Ti has elapsed after the general-purpose motor 2 is stopped. Set larger than the time required for coasting.

[0007]

According to the mold clamping force setting method for the toggle type mold clamping device according to the present invention, when the general-purpose motor 2 is stopped when the crosshead 5 of the toggle mechanism 3 reaches the mold clamping force setting position, The entire toggle mechanism 3 is stopped by passing the general-purpose motor 2 past a normal position. In the present invention, thereafter, the general-purpose motor 2 is operated for a preset correction time Ts, and the entire toggle mechanism 3 is moved in the opposite direction, that is, moved forward. Therefore, the retreat distance due to coasting is offset, and the toggle mechanism 3 is accurately set to the regular position where the original mold clamping force is exerted. By providing the interval time Ti, during movement of the general-purpose motor 2 by coasting,
The forward movement based on the setting of the correction time Ts is prevented from starting.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, the overall construction of a toggle type mold clamping device 1 capable of carrying out the method of the present invention will be described with reference to FIG.

Reference numeral 10 denotes a mold clamping device bed, on one side of which a fixed platen 11 is erected and installed. The fixed die 12s of the die 12 is attached to the substantially central portion of the fixed board 11, and one end of each tie bar 13 is fixed to the four corners so as to be parallel to the horizontal direction. An injection device (not shown) is installed so as to face the stationary platen 11, and constitutes an injection molding machine together with the main mold clamping device 1. Further, screw parts 14 are provided on the other end side of the tie bars 13. On the other hand, a movable platen 15 is slidably mounted on the tie bars 13 ... And a movable die 12t is attached to the movable platen 15 substantially at the center thereof. On the other hand, a pressure receiving plate (toggle receiving plate) 16 is slidably mounted on the other side of the tie bars 13 ... And a toggle mechanism 3 is installed between the pressure receiving plate 16 and the movable plate 15. The toggle mechanism 3 includes a pressure receiving plate 16 and a movable plate 1.
Front toggle links 3f, 3f and rear toggle links 3r, 3r for connecting 5 are provided at the top and bottom, and rear toggle links 3r, 3
The r is connected to the crosshead 5 arranged at the center via the intermediate toggle links 3m and 3m, and has a ball nut 17 inside the crosshead 5 and is screwed into the ball screw 18. The rear end side of the ball screw 18 is rotatably attached to the pressure receiving plate 16 and is rotated by a servo motor 21 via a rotation transmission mechanism 20. The rotation transmission mechanism 20 and the servo motor 21 constitute the toggle drive unit 4.

Further, a mold thickness adjusting nut 22 is screwed onto the thread portion 14 of the tie bar 13. The mold thickness adjusting nut 22 is rotatably connected to the pressure receiving plate 16, and is rotated by a geared motor 2g (general-purpose motor 2) with a brake via a rotation transmission mechanism 23. The geared motor 2g is attached to the pressure receiving plate 16.

On the other hand, 24 is a central controller. The central controller 24 contains a microcomputer,
It has a control function of the entire injection molding machine including the mold clamping device 1 and the injection device. The central controller 24 is a ROM storing a control program for executing the mold clamping force setting method according to the present invention.
25, RAM 26 for temporary storage of data and arithmetic processing
, A display 27, an input device 28, and the like.

Further, the central controller 24 is connected to the servo motor 21 via the servo motor control unit 29, and is also connected to an encoder (rotational position detector) 30 built in the servo motor 21. Servo motor control unit 29
Is the servomotor 21 according to a command from the central controller 24.
Is driven to control the speed and position of the crosshead 5, and torque limit control is performed on the output torque of the servomotor 21. Thereby, the forward force and the backward force of the crosshead 5 are controlled. The encoder 30 is an absolute type and detects the position and speed of the crosshead 5 and applies the detected position and speed to the central controller 24. In this case, the most advanced position (mold clamping position) of the crosshead 5 where the toggle mechanism 3 spreads to the maximum becomes zero (0), and the direction in which the toggle mechanism 3 contracts (mold opening direction) becomes plus (+),
The position of the movable platen 15 is controlled based on this. Further, the geared motor 2g is connected to the central controller 24 via the geared motor controller 31. The geared motor control unit 31 operates the geared motor 2g in response to a command from the central controller 24 to perform movement control or holding control of the pressure receiving plate 16.

Next, the mold clamping force setting method according to the present invention will be described with reference to the flowchart shown in FIG.

Prior to the control, the fixed mold 12s of the mold 12 is mounted on the fixed plate 11 and the movable mold 12t is mounted on the movable plate 15. Further, various data such as mold clamping force and mold thickness are input by the input device 28. Thereby, the central controller 24 calculates the position of the crosshead 5 corresponding to the mold clamping force, and stores it in the RAM 26 as the mold clamping force setting position Po.

On the other hand, when a mold clamping force setting command is issued, R
The control program is read from the OM 25, and the process for automatically setting the mold clamping force is executed.

First, the servomotor 21 advances the crosshead 5 with the output torque limited by the torque limit set value L1 (step 51). The toggle mechanism 3 is contracted in advance. The torque limit setting value L1 is set in advance to a predetermined size that allows the movable platen 15 to move. The position P of the crosshead 5 is read by the encoder 30 and is updated and stored in the RAM 26 as the position P1 (step 52).
The position P2 after the elapse of o is read and updated and stored in the RAM 26 (steps 53 and 54). Thus, time T
The position P is sequentially detected each time o has elapsed, and the positions P1 and P are detected.
When the positions P1 and P2 match by comparing 2 with each other, the forward movement of the crosshead 5 is stopped (steps 55 and 56). This state is a mold touch state in which the position of the crosshead 5 does not change.

Then, the position P of the crosshead 5 is compared with the mold clamping force setting position Po, and if P≤Po (die non-touch), alarm processing is performed and an alarm is issued (step 57,
58). In this case, it is also possible to perform a die touch control process described later. On the other hand, in the case of P> Po, the crosshead 5 is moved forward while the output torque of the servomotor 21 is limited by the torque limit set value L2, and the toggle mechanism 3 is gradually widened while maintaining the die touch state. Control (step 59). At this time, at the same time,
The geared motor 2g is actuated in the direction in which the pressure receiving platen 16 is retracted, and the toggle mechanism 3 is controlled to be retracted (step 60). The torque limit set value L2 is smaller than the set value L1 and the mold can be touched,
The tie bar 13 is set to a predetermined size that is too small to extend. Then, when the position P of the crosshead 5 reaches the mold clamping force setting position Po, the operation of the servo motor 21 and the geared motor 2g is stopped. This allows
When the crosshead 5 stops moving forward, the pressure receiving plate 16
Retreat stops. Further, the torque limit control is released, and control for holding the crosshead 5 at the stop position is performed (steps 61, 62, 63).

On the other hand, after the geared motor 2g is stopped, the interval time Ti is measured by the timer (step 64). The interval time Ti is a rest time, and is set to be longer than the time required from the time the stop command is issued to the geared motor 2g to the actual stop. Furthermore, after the lapse of the interval time Ti,
The geared motor 2g is operated in the direction in which the entire toggle mechanism 3 moves forward. This operation is continued by a timer for a preset correction time Ts (steps 64, 65, 6).
6). It is desirable to set the correction time Ts to at least a time at which the coasting distance after the geared motor 2g is stopped and the coasting distance after the geared motor 2g is stopped can be offset, and is usually a short time of about 0.2 seconds. To set. Therefore, burnout of the motor is prevented.
When the correction time Ts has elapsed, the geared motor 2g is finally stopped (step 67), and a preset processing time Te required until the pressure receiving plate 16 finally stops from the time when the stop command is issued is set. When the time has passed, all the steps of the mold clamping force setting process are ended (step 6).
8). As a result, the crosshead 5 is set at a regular position where the set mold clamping force can be exerted. Therefore, when the crosshead 5 is moved to the mold clamping force setting position (P = 0) during the mold clamping process, the set mold clamping force is generated, and the accurate mold clamping force can always be set.

At the start of the mold clamping force setting process,
Depending on the position of the pressure platen 16, the position P of the crosshead 5
Is smaller than the mold clamping force setting position Po (P ≦ Po). In this case, an alarm can be issued by the alarm process (step 58) as described above, and the mold touch control process is performed according to the flowchart shown in FIG. 3 to set the mold clamping force on the pressure receiving platen 16. It is also possible to move forward to a mold touch state where processing can be executed.

Next, the mold touch control process will be described with reference to FIG.
Will be described with reference to.

In step 57, the position P of the crosshead 5 is compared with the mold clamping force setting position Po, and if P≤Po, mold touch control processing is performed (step 7).
1). First, the servo motor 21 is operated with the output torque being limited by the torque limit setting value L3, and the crosshead 5 is retracted to gradually contract the toggle mechanism 3 (step 72), and at the same time, to the geared motor 2g. Is operated to move the pressure receiving platen 16 forward (step 73). The torque limit set value L
3 is relatively small and is preset to a size that allows the movable platen 15 to move. Then, when the crosshead 5 reaches the position where P> Po, the backward movement of the crosshead 5 is stopped, and control for holding the position of the crosshead 5 while controlling the output torque is executed (steps 74, 7).
5). Further, when the pressure receiving platen 16 further moves forward and becomes in the mold touch state, the movement of the movable platen 15 is stopped. In this case, the forward force of the pressure receiving plate 16 acts on the crosshead 5,
Since the position of the crosshead 5 changes, the crosshead 5
The mold touch state can be detected by changing the position of. Therefore, when this position change is detected, the operation of the geared motor 2g may be stopped so as to stop the forward movement of the pressure receiving platen 16. As a result, the die touch control process is completed (steps 76 and 77).

On the other hand, as a method for mounting the die 12,
The movable platen 15 (cross head 5) is set to the rearmost retracted position, and first the mold 12 is attached to the fixed platen 11 to adjust the mold thickness and the movable platen 15 is brought into contact with the mold plate 12.
Finally, the mold 12 may be attached to the movable platen 15.

Next, the method for setting the mold clamping force in this case will be described with reference to the flowchart shown in FIG.

First, when a mold clamping force setting command is issued, the central controller 24 executes an automatic mold clamping force setting process according to a predetermined control program.

The servo motor 21 limits the output torque according to the torque limit setting value L1 and the cross head 5
Is moved forward at a low speed (step 81). Then, in order to confirm whether or not the mold is touched, it is constantly monitored whether or not the position of the crosshead 5 changes. If it is confirmed that the position of the crosshead 5 does not change, the mold touch control process is ended (step 82).

On the other hand, the position P of the crosshead 5 is monitored,
When P> Po, the forward movement of the crosshead 5 is stopped. Further, the torque limit set value L2 is changed to control to hold the crosshead 5 at the stop position (steps 83 and 84), and at the same time, the geared motor 2g is operated to move the pressure receiving plate 16 forward (step 85). .
On the other hand, if the position of the crosshead 5 stops changing,
The operation of the geared motor 2g is stopped, and the forward movement of the pressure receiving platen 16 is stopped, thereby ending the mold touch control process (steps 86 and 87). In this case, the position of the crosshead 5 at the time of touching the mold is Po, but it may be fixed at a position where the maximum mold clamping force can be generated.

When the mold touch control process is completed, the same processes as the steps after step 59 described in the flowchart of FIG. 1 are executed to complete the mold clamping force setting process. In FIG. 4, the same steps as those in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

Although the embodiments have been described in detail above, the present invention is not limited to such embodiments. For example, the general-purpose motor is exemplified by a geared motor with a brake, but various motors having no position control function are applied. In addition, the detailed configuration, method, and the like can be arbitrarily changed without departing from the scope of the present invention.

[0030]

As described above, according to the method for setting the mold clamping force of the toggle type mold clamping device according to the present invention, the general purpose motor causes the entire toggle mechanism to retreat, and at the same time, the toggle drive section clamps the crosshead of the toggle mechanism. When the crosshead reaches the mold clamping force setting position while maintaining the mold touch state by advancing the toggle mechanism in the direction of expanding the force from before the force setting position,
When the general-purpose motor and the toggle drive unit are stopped, and the position of the entire toggle mechanism is adjusted according to the mold thickness, after stopping the general-purpose motor, the general-purpose motor is preset to a predetermined direction in which the entire toggle mechanism moves forward. Since it is operated only for the correction time, even when using a general-purpose motor,
It has a remarkable effect that an accurate mold clamping force can be set according to the mold thickness and can be easily implemented by changing a control program or the like.

[Brief description of drawings]

FIG. 1 is a flowchart showing a procedure of a mold clamping force setting method according to the present invention,

FIG. 2 is a configuration diagram of a mold clamping device capable of implementing the same mold clamping force setting method,

FIG. 3 is a flowchart showing a procedure when performing a mold touch control process,

FIG. 4 is a flowchart showing a procedure of another embodiment according to the mold clamping force setting method,

[Explanation of symbols]

 1 Toggle type mold clamping device 2 General-purpose motor 3 Toggle mechanism 4 Toggle drive unit 5 Crosshead

Claims (4)

[Claims] 1. A general-purpose motor causes the entire toggle mechanism to retreat, and at the same time, a toggle drive unit causes a crosshead of the toggle mechanism to move forward from a position before a mold clamping force setting position in a direction of expanding the toggle mechanism to maintain a mold touch state. Also, when the crosshead reaches the mold clamping force setting position, the general-purpose motor and the toggle drive unit are stopped, and the position of the entire toggle mechanism is adjusted according to the mold thickness. In the setting method, after stopping the general-purpose motor,
A method for setting a mold clamping force for a toggle type mold clamping device, which comprises operating a general-purpose motor in a direction in which the entire toggle mechanism moves forward for a predetermined correction time set in advance. 2. A mold clamping force setting method for a toggle type mold clamping device, wherein the correction time is set to be at least a time capable of canceling coasting after the stop of the general-purpose motor. 3. The mold clamping force setting for the toggle mold clamping device according to claim 1, wherein the general-purpose motor is operated only for a correction time after a preset predetermined interval time has elapsed after being stopped. Method. 4. The mold clamping force setting method for a toggle type mold clamping device according to claim 3, wherein the interval time is set to be larger than the time required for coasting after the general-purpose motor is stopped.