JPH04278318A - Mold clamping force setting method of toggle type mold clamping device - Google Patents

Abstract

PURPOSE:To compensate the retreating distance due to inertial movement and consequently enhance the positioning accuracy of molds by a method wherein a general-purpose motor, with which the whole toggle mechanism is moved, is actuated for the predetermined correction time so as to move the whole toggle mechanism forwards after its stoppage. CONSTITUTION:When the setting command of mold clamping force is issued, firstly a cross head 5 is moved forward with a servo motor 21. At this time, the position of the crosshead 5 is read with an encoder 30 and stored in a RAM 26. The contents of the RAM 26 is renewed at every predetermined period of time so as to control the movement of the crosshead 5 in response to the result of the comparison of the position of the crosshead before renewal with that after renewal. Under the condition that the crosshead 5 is kept on being under mold touch state, toggle mechanism 3 is gradually widened with a general purpose motor 2. When the crosshead 5 reaches the setting position of mold clamping force, the servo motor 21 and the general purpose motor 2 are stopped. After that, the general purpose motor 2 is actuated for the predetermined correction time so as to move the whole toggle mechanism forwards.

Description

[Detailed description of the invention]

0001

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

0002

2. Description of the Related Art Generally, a mold clamping device of an injection molding machine applies a predetermined clamping force to a mold. In the case of a toggle type mold clamping device, the mold clamping force is proportional to the elongation of the tie bars during mold clamping due to the characteristics of the toggle mechanism. For this reason, in the toggle type mold clamping device, after installing the mold, the toggle mechanism is expanded to the maximum and the mold is clamped. The position of the entire toggle mechanism was adjusted according to the mold thickness.

[0003] Conventionally, such a mold clamping force setting method has been disclosed in Japanese Patent Publication No. 61-35924 and Japanese Patent Application Laid-Open No. 1-27501.
It is known from Publication No. 6, etc. The former uses a mold clamping cylinder as the drive source of the toggle mechanism, and the latter uses a servo motor as the drive source, and the basic setting method is the same. In the latter case, a tie bar with a threaded portion formed at the rear is provided, and a movable plate supporting the movable mold and a pressure receiving plate (toggle receiving plate) are slidably loaded on this tie bar, and a At the same time, a toggle mechanism is installed on the screw portion, and a mold thickness adjusting nut rotated by a general-purpose motor is screwed onto the threaded portion, and this mold thickness adjusting nut is rotatably connected to the pressure receiving plate. Then, when setting the mold clamping force, the output torque of the servo motor is limited.
The servo motor and general-purpose motor are driven to touch the mold at a position where the crosshead in the torque mechanism is retracted from the mold clamping force setting position, and after detecting the mold touch, the movable crosshead driven by the toggle mechanism The speed of the servo motor is controlled in accordance with the drive speed of the general-purpose motor so that the forward speed of the board and the backward speed of the entire toggle mechanism are approximately the same.When the crosshead reaches the mold clamping force setting position, both motors stop at the same time. Thereby, 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. In other words, the motor used as the drive source to move the entire toggle mechanism and adjust the mold thickness is for the purpose of simply adjusting the position.
Furthermore, general-purpose motors that do not require position control are used because overloads are less likely to occur and position control is not required. Therefore, if the general-purpose motor is stopped when the crosshead reaches the mold clamping force setting position, the stopping position will actually become unstable due to coasting due to the inertia of the general-purpose motor, and in the end, the accurate mold clamping force cannot be set. The problem was that it could not be configured.

[0005] The present invention solves the problems that exist in the conventional technology, and is a toggle type that can always set an accurate mold clamping force according to the mold thickness even when a general-purpose motor is used. The purpose of this invention is to provide a method for setting the mold clamping force of a mold clamping device.

[0006]

[Means for Solving the Problems] A mold clamping force setting method for a toggle type mold clamping device according to the present invention is such that the general-purpose motor 2 is used to retract the entire toggle mechanism 3, and at the same time, the toggle drive unit 4 is used to cross the toggle mechanism 3. The head 5 is moved forward in the direction of spreading the toggle mechanism 3 from before the mold clamping force setting position, and while maintaining the mold touching state, when the crosshead 5 reaches the mold clamping force setting position, the general-purpose motor 2 and the toggle mechanism 3 are moved forward. When stopping the drive unit 4 and adjusting the position of the entire toggle mechanism 3 according to the mold thickness, after stopping the general-purpose motor 2, the general-purpose motor 2 is further set in advance in the direction in which the entire toggle mechanism 3 moves forward. It is characterized in that it is operated only for a predetermined correction time Ts. In this case, the correction time Ts is set to at least a time that can offset coasting after the general-purpose motor 2 stops. Note that after the general-purpose motor 2 has been stopped, it is desirable to operate it for a correction time Ts after a preset predetermined interval time Ti has elapsed. Set it to be larger than the time required for coasting.

[0007]

[Operation] According to the mold clamping force setting method for a 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 stops after passing the normal position due to coasting of the general-purpose motor 2. In the present invention, after this,
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,
The toggle mechanism 3 is accurately set at the normal position where it exerts its original mold clamping force. Note that by providing the interval time Ti, forward movement based on the setting of the correction time Ts is prevented from starting while the general-purpose motor 2 is moving by coasting.

[0008]

Embodiments Next, preferred embodiments of the present invention will be described in detail with reference to the drawings.

First, the overall structure of a toggle type mold clamping device 1 that can carry out the method of the present invention will be explained with reference to FIG.

Reference numeral 10 denotes a mold clamping device bed, on one side of which a fixed platen 11 is installed in an upright manner. A fixed mold 12s of the mold 12 is attached to the substantially center of the fixed platen 11, and one end of tie bars 13 are fixed to each of the four corners so as to be parallel to the horizontal direction. Note that an injection device (not shown) is installed opposite the fixed platen 11, and constitutes an injection molding machine together with the mold clamping device 1. Further, a threaded portion 14 is provided on the other end side of the tie bar 13. On the other hand, a movable platen 15 is slidably loaded on the tie bars 13, and a movable mold 12t is attached approximately at the center of the movable platen 15. On the other hand, a pressure receiving plate (toggle receiving plate) 16 is slidably mounted on the other side of the tie bar 13, and a toggle mechanism 3 is installed between the pressure receiving plate 16 and the movable platen 15. The toggle mechanism 3 includes a pressure receiving plate 16 and a movable plate 1
The front toggle links 3f, 3f and the rear toggle links 3r, 3r are provided on the top and bottom to connect the rear toggle links 3r, 3
r is connected to a centrally placed crosshead 5 via intermediate toggle links 3m, 3m, and has a ball nut 17 inside the crosshead 5, which is screwed into a 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 section 4.

Furthermore, a die thickness adjusting nut 22 is screwed into the threaded 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. Note that 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 has a built-in microcomputer,
It has a control function for the entire injection molding machine including the mold clamping device 1 and the injection device. The central controller 24 is a ROM that stores 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 servo motor 21 is connected to the central controller 24 via a servo motor control section 29, and an encoder (rotational position detector) 30 built into the servo motor 21 is connected thereto. Servo motor control section 29
is activated by the servo motor 21 according to the command from the central controller 24.
, and controls the speed and position of the crosshead 5, and performs torque limit control on the output torque of the servo motor 21. Thereby, the forward force and backward force of the crosshead 5 are controlled. The encoder 30 is of an absolute type, detects the position and speed of the crosshead 5, and provides 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 is expanded to the maximum becomes zero (0), and the direction in which the toggle mechanism 3 is contracted (mold opening direction) becomes plus (+).
Based on this, the position of the movable platen 15 is controlled. Further, the geared motor 2g is connected to the central controller 24 via a geared motor control section 31. The geared motor control section 31 operates the geared motor 2g according to a command from the central controller 24, and controls the movement or holding of the pressure receiving plate 16.

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

Prior to control, the fixed die 12s of the mold 12 is attached to the fixed platen 11, and the movable die 12t is attached to the movable platen 15. In addition, various data such as mold clamping force and mold thickness are inputted using 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 the mold clamping force setting command is issued, R
A control program is read from the OM 25, and automatic mold clamping force setting processing is executed.

First, the servo motor 21 advances the crosshead 5 with the output torque limited by the torque limit setting value L1 (step 51). Note that the toggle mechanism 3 is contracted in advance. The torque limit setting value L1 is preset to a predetermined magnitude that allows the movable platen 15 to be moved. The position P of the crosshead 5 is read by the encoder 30 and updated and stored in the RAM 26 as the position P1 (step 52).
The position P2 after o has elapsed is read and updated and stored in the RAM 26 (steps 53, 54). In this way, time T
Detect position P sequentially every time o elapses, and detect position P1 and position P.
2, and if the positions P1 and P2 match, the forward movement of the crosshead 5 is stopped (steps 55, 56). This state is a mold touching state in which the position of the crosshead 5 does not change.

Then, the position P of the crosshead 5 and the mold clamping force setting position Po are compared, and if P≦Po (mold not touched), an alarm process is performed and an alarm is issued (step 57,
58). In this case, it is also possible to perform mold touch control processing, which will be described later. On the other hand, in the case of P>Po, the crosshead 5 is moved forward with the output torque of the servo motor 21 being limited by the torque limit setting value L2, and the toggle mechanism 3 is gradually expanded while maintaining the mold touch state. (Step 59). At this time, at the same time,
The geared motor 2g is operated in the direction in which the pressure receiving plate 16 retreats, and the entire toggle mechanism 3 is controlled to retreat (
Step 60). The torque limit setting value L2 is smaller than the setting value L1, and is set to a predetermined size that allows the mold to be touched but is too small to extend the tie bars 13. 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. As a result, the forward movement of the crosshead 5 is stopped, and the backward movement of the pressure receiving plate 16 is also stopped. Also, the torque limit control is canceled and
Furthermore, control is performed to hold the crosshead 5 at the stop position (steps 61, 62, 63).

On the other hand, after stopping the geared motor 2g, an interval time Ti is measured by a timer (step 64). The interval time Ti is a rest time, and is set to be larger than the time required from when a stop command is issued to the geared motor 2g until it actually stops. Furthermore, after the interval time Ti has elapsed, the geared motor 2g is operated in a 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, 66).
. It is desirable to set the correction time Ts to at least a time that can offset the coasting distance after a stop command is issued to the geared motor 2g and the geared motor 2g is stopped, and is usually a short time of around 0.2 seconds. Set. Therefore, burnout of the motor and the like are prevented. When the correction time Ts has elapsed, the geared motor 2g is finally stopped (step 67), and the preset processing time Te required from the time when the stop command is issued until the pressure receiving plate 16 finally stops is stopped. Once the time has elapsed, complete the entire mold clamping force setting process (step 6).
8). Thereby, the crosshead 5 is set at a normal position where it can exert the set mold clamping force. Therefore, by moving the crosshead 5 to the mold clamping force setting position (P=0) during the mold clamping process, the set mold clamping force is generated and an accurate mold clamping force can be set at all times.

[0020] Furthermore, at the start of the mold clamping force setting process,
Depending on the position of the pressure receiving plate 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. It is also possible to advance the process to an executable mold touch state.

Next, regarding the mold touch control process, FIG.
Explain with reference to.

In step 57, the position P of the crosshead 5 and the mold clamping force setting position Po are compared, and if P≦Po, mold touch control processing is performed (step 71).
. First, the servo motor 21 is set to the torque limit setting value L3.
The toggle mechanism 3 is gradually retracted by operating the crosshead 5 with the output torque limited (step 72), and at the same time, the geared motor 2g is operated to advance the pressure plate 16 (step 72). Step 73). Note that the torque limit setting value L3 is relatively small and is preset to a size that allows the movable platen 15 to be moved. When the crosshead 5 reaches a position where P>Po, the backward movement of the crosshead 5 is stopped, and control is executed to maintain the position of the crosshead 5 while controlling the output torque (steps 74 and 75). )
. Further, when the press platen 16 moves further forward and comes into contact with the mold, the movement of the movable platen 15 is stopped. In this case, the forward force of the press plate 16 acts on the crosshead 5 and the position of the crosshead 5 changes, so that the state of mold touch can be detected from the change in the position of the crosshead 5. Therefore, when this position change is detected, the operation of the geared motor 2g may be stopped in order to stop the pressure receiving plate 16 from moving forward. This ends the mold touch control process (steps 76 and 77).

On the other hand, the method for attaching the mold 12 is as follows.
Set the movable platen 15 (crosshead 5) to the most retracted position, first attach the mold 12 to the fixed platen 11 to adjust the mold thickness, etc., bring the movable platen 15 into contact with the mold 12, and finally , the mold 12 may be attached to the movable platen 15.

Next, the mold clamping force setting method in this case will be explained according to the flowchart shown in FIG.

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

The servo motor 21 operates the crosshead 5 with its output torque limited by the torque limit setting value L1.
is advanced at low speed (step 81). Then, in order to confirm whether or not the mold is being touched, whether or not the position of the crosshead 5 changes is constantly monitored. 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,
If P>Po, the forward movement of the crosshead 5 is stopped. In addition, the torque limit setting value L2 is changed to perform control to hold the crosshead 5 at the stop position (
Steps 83 and 84), and simultaneously operate the geared motor 2g to advance the pressure receiving plate 16 (Step 85). On the other hand, if the position of the crosshead 5 no longer changes,
By stopping the operation of the geared motor 2g and stopping the forward movement of the pressure receiving plate 16, the mold touch control process is completed (steps 86 and 87). In this case, the position of the crosshead 5 when touching the mold is set to the above 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 process as the steps after step 59 described in the flowchart of FIG. 1 is executed to complete the mold clamping force setting process. Note that in FIG. 4, the same steps as in FIG. 1 are given the same reference numerals, and detailed explanation thereof will be omitted.

Although the embodiments have been described in detail above, the present invention is not limited to these embodiments. For example, although a geared motor with a brake is exemplified as a general-purpose motor, various motors without a position control function may be applied. In addition, the detailed structure, method, etc. may be arbitrarily changed without departing from the gist of the present invention.

[0030]

Effects of the Invention As described above, the mold clamping force setting method for a toggle type mold clamping device according to the present invention is capable of retracting the entire toggle mechanism using a general-purpose motor, and at the same time, clamping the crosshead of the toggle mechanism using the toggle drive unit. Move the toggle mechanism forward in the direction of spreading it from before the force setting position, and while keeping it in contact with the mold, when the crosshead reaches the mold clamping force setting position,
When stopping the general-purpose motor and toggle drive unit and adjusting the position of the entire toggle mechanism according to the mold thickness, after stopping the general-purpose motor, move the general-purpose motor to a preset direction in which the entire toggle mechanism moves forward. Because it operates only during the correction time, even when using a general-purpose motor,
This has the remarkable effect that it is possible to set an accurate mold clamping force according to the mold thickness, and that it can be easily implemented by changing the control program.

[Brief explanation of the drawing]

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

[Figure 2] A configuration diagram of a mold clamping device that can implement the same mold clamping force setting method,

FIG. 3 is a flowchart showing the procedure for performing mold touch control processing;

FIG. 4 is a flowchart showing the procedure of another embodiment using the same mold clamping force setting method;

[Explanation of symbols]

1 Toggle type mold clamping device 2 General purpose motor 3 Toggle mechanism 4 Toggle drive part 5 Cross head

Claims (4)

[Claims] [Claim 1] At the same time, the general-purpose motor moves the entire toggle mechanism backward, and at the same time, the toggle drive unit moves the crosshead of the toggle mechanism forward from before the mold clamping force setting position in the direction of expanding the toggle mechanism, thereby maintaining the mold touching state. At the same time, when the crosshead reaches the mold clamping force setting position, the general-purpose motor and 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 mold clamping force setting method for a toggle-type mold clamping device, comprising operating a general-purpose motor in a direction in which the entire toggle mechanism moves forward for a predetermined correction time. 2. A mold clamping force setting method for a toggle type mold clamping device, characterized in that the correction time is set to at least a time that can offset coasting after the general-purpose motor stops. 3. The mold clamping force setting of the toggle type mold clamping device according to claim 1, wherein the general-purpose motor is stopped and then operated for a correction time after a predetermined interval time has elapsed. 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.