JPH0486207A - Automatic setting method for mold clamping force of toggle type mold clamping device - Google Patents

Abstract

PURPOSE:To make it possible to automatically set mold clamping force accurately only by giving values by a method wherein the set position of a pad platen is calculated on the basis of the set values of mold thicknesses and of mold clamping force and set so as to stop the moving pad platen when the platen reaches the set position and to detect its stop position in order to compare the detected value with the set position of the pad platen. CONSTITUTION:A central controller 14 calculates the set position, at which the set mold clamping force is to be developed, of a pad platen l on the basis of the set values of mold thicknesses and of mold clamping force and set the calculated set position and, after that, issues command to a motor 17 for controlling the position of the pad platen l. In accordance with the command, the motor 17 pivots so as to drive a chain 19 in order to pivot a sprocket 16 together with 15 by the predetermined amount, resulting in moving the pad platen 1 to the set position. When the pad platen 1 reaches said set position, the motor 17 is stopped and the position of the pad platen 1 is detected. After that, the detected position of the pad platen 1 is compared with the set position of the pad platen l so as to judge whether the comparison result lies within the allowable value or not. When the result lies within the allowable value, the setting process of mold clamping force is brought to and end. When the result does not lie within the allowable value, the position of a crosshead 6, at which the set mold clamping force is to be developed, is calculated. After that, by setting said calculated value as a mold clamping position, the setting process of mold clamping force is brought to an end.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for automatically setting the mold clamping force of a toggle type mold clamping device of an injection molding machine. [Prior art] The method for setting the mold clamping force of a toggle-type mold clamping device is that due to the characteristics of the mechanism, the extension of the tie bars during mold clamping acts as mold clamping force, so when the toggles are fully extended during mold clamping, the tie bars are The method involved delicately adjusting the position of the pressure receiving plate so that the amount of elongation was approximately equal to the set mold clamping force. Various methods have been devised to automatically set the mold clamping force, but each method is set by delicately adjusting the position of the pressure receiving plate. They differ in the method of detecting the mold clamping force or the method of moving the pressure receiving plate to the set position, but they detect or predict the mold clamping force and feed back the correction amount to the mold thickness adjustment means of the toggle device. The mold clamping force setting method involved adjusting the mold clamping force by subtly adjusting the position of the pressure receiving plate. [Problems to be Solved by the Invention] However, in setting the mold clamping force, it is not easy to move the entire toggle device with high precision using the mold thickness adjusting means, and the operation is complicated. An object of the present invention is to provide a new automatic mold clamping force setting method that can automatically and accurately set the mold clamping force by simply providing the mold thickness and mold clamping force set values. [Means for Solving the Problems] The present invention according to the above object is characterized by a toggle type in which rotational motion by a servo motor is converted into linear motion and transmitted to a toggle mechanism cross head, and the movable platen is moved by the toggle mechanism. The output torque of the above servo motor of the mold clamping device is
A control device equipped with a torque limit function that limits two limit values, a sensor that detects the position of the crosshead from the amount of rotation of the servo motor, and a pressure receiving plate position detector at a predetermined location are installed. A control means is provided, and when setting the mold clamping force, the thickness of the mold and the mold clamping force are set, and the setting position of the pressure receiving plate that generates the set mold clamping force is calculated and set from those set values, The pressure receiving plate is moved by the pressure receiving plate position control means described in ``2, and when the above set value is reached, the movement of the pressure receiving plate is stopped, the stop position of the pressure receiving plate is detected, and the detected value and the pressure receiving plate described in ``1'' are Compare with the set position, determine whether the value is an allowable value, and if it is an allowable value, set the mold clamping force] - end the process, and if it is not an allowable value, generate the set mold clamping force The purpose is to calculate the position of the crosshead and set that value as the mold clamp position. [Operation] Assuming that the crosshead position is at a position where the pressure receiving plate can move freely, when the mold clamping force setting process is started, the central controller calculates the set mold from the mold thickness and mold clamping force setting values. Calculate and set the setting position of the pressure receiving plate that generates the tightening force,
The pressure receiving plate is moved by giving a command to the motor means for controlling the pressure receiving plate position, and when the pressure receiving plate reaches the set position described in 1, the movement of the pressure receiving plate is stopped, the stop position of the pressure receiving plate is detected, and the detected value and the above Compare the pressure receiving plate setting position of The position of the crosshead to be applied is calculated, and that value is set as the mold clamping position, and the mold clamping force setting step is completed. [Embodiment] In the figure, 1 is a pressure receiving plate, 2 is a fixed plate, and both plates are connected by tie bars 3, 3 provided over the four corners. A movable plate 4 is inserted through the tie bars 3, 3 and provided between the pressure receiving plate 1 and the fixed plate 2, and is connected to the pressure receiving plate 1 by a toggle mechanism 5. A ball nut 7 is installed inside the crosshead 6 at the center of the L-glue mechanism 5, and a ball screw shaft 8 is rotatably attached to the pressure receiving plate 1. This ball screw shaft 8 and the above-mentioned pole nut 7 are screwed together, and the rotational motion of the ball screw shaft 8 in a fixed position is converted into a linear motion by the pole nut 7, and the expansion and contraction of the links 5a and 5a due to the movement of the crosshead 6, The movable platen 4 moves forward and backward with respect to the fixed platen 2, and opens, closes, and clamps a mold 9 attached to opposing sides of the fixed platen 2 and the movable platen 4. The toggle mechanism 5 is driven by a servo motor 10 attached to the pressure receiving plate. This servo motor 10 and the ball screw shaft 8 are connected via a drive belt 11, and the servo motor 10 has a torque limit function that limits the output torque of the servo motor. A control device 12 and a sensor 13 (encoder) for detecting the position of the crosshead 6 from the amount of rotation of the servo motor are provided. Furthermore, the sensor 13 and the control device 12 are connected to a central controller 14 . This central controller 14 is a control device that is equipped with a CRT device as a display equipped with a microcomputer and is in charge of overall control of the injection molding machine. The RAM and input/output device for controlling the servo motor are capable of numerical calculation processing. 15 is a nut for controlling the pressure plate position, and sprocket 16
The sprocket 16 is wound around the sprocket 18 of the motor 17 for controlling the pressure plate position fixed to the pressure plate 1. An encoder detector 20 is provided which is rotated by a chain 19 and detects the position of the pressure receiving plate 1 from the amount of rotation. The position detector 2o and the motor 17 are connected to the central controller 14. In the above configuration, assuming that the crosshead position is at a position where the ash receiving plate 1 can freely move, when the mold clamping force setting process is started, the central controller 14 determines, based on the set values of the mold thickness and mold clamping force, The set position of the ash receiver 1 that generates the set mold clamping force is calculated, and after setting it, a command is issued to the motor 17 for controlling the ash receiver position. The motor 17 rotates according to the command and the chain 19
15 is rotated by a predetermined amount together with the sprocket 16 to move the pressure receiving plate 1 to a set position. When the pressure receiving plate 1 reaches the set position, the motor 17 is stopped and the position is detected. This detected position is compared with the set position of the ash receiving plate 1, and it is determined whether the value is an allowable value or not. If it is an allowable value, the mold clamping force setting process is completed, and if it is not an allowable value, the mold clamping force setting process is completed. , calculate the position of the crosshead 6 that generates the set mold clamping force. Then, this value is set as the mold clamping position, and the mold clamping force setting step is completed. FIG. 2 is a flowchart showing the second process. When setting the mold thickness above, if the exact value of the mold thickness is unknown or if the machine is not precisely controlled with absolute dimensions, set the mold thickness using the machine's special dimensions. It is necessary to set the thickness of In such a case, the mold thickness detection step may be performed before the mold clamping force setting step to allow the machine to detect the mold thickness. One example of this method is to move the crosshead to the mold clamp position after retracting the ash catcher to the end, move the crosshead forward to touch the mold, and then move the crosshead until the ash catcher is in contact with the mold. The mold thickness can be calculated from the position of the ash receiving plate by detecting the position where it has stopped moving. FIG. 3 is a flowchart showing the mold thickness detection process. Further, an incremental encoder may be used as the ash receiving plate position detection sensor. In this case, the above mold thickness detection process is first performed and the mold is touched, and since the mold touch position is also the mold thickness position, it is necessary to extend the tie bars using the mold touch position as a reference point. The mold clamping force setting can be controlled using the amount as the setting position of the ash receiving plate. [Effects of the invention] In this invention, which is composed of structural acid, the elongation of the tie bars during mold clamping is proportional to the mold clamping force, so in order to generate the mold clamping force, it is sufficient to control the elongation of the tie bars. If the exact thickness of the mold is given, the elongation of the tie bar required to generate the mold clamping force can be calculated, and the elongation of the ash receiving plate and moving plate during mold clamping can be calculated from the gluing loss head position during mold clamping. Since the relative distance can be calculated, by subtracting the elongation of the tie bar from the mold thickness position, the set position of the ash catcher that generates the set mold clamping force can be calculated. Therefore, when the pressure receiving plate is positioned at the set position, the set mold clamping force is set. In addition, when the ash receiving plate position differs from the set position, by calculating from the error value of the ash receiving plate position and changing the crosshead position during mold clamping, the amount of movement of the movable plate corresponding to the error described in 2. By changing the amount of extension of the tie bar, it is possible to correct the extension amount of the tie bar to be the same as the set value, thereby making the mold clamping force match the set value. Furthermore, the position of the ash receiving board and the mold clamping position can be controlled by digital control, and the mold clamping force can be easily set, resulting in high work efficiency and no need for a device to measure the mold clamping force. It does not require delicate adjustment of the board, and has the advantage that a general-purpose induction motor can be used as the motor for the ash receiving board position control means. 13...Sensor for cross head position detection 14...Central controller) Roll 15
・・・・・・Mold thickness adjustment nut 17・・・・・・・・・
・Motor 20 for controlling the position of the pressure receiving plate...Position detector of the pressure receiving plate

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the automatic mold clamping force correction method of this invention, Fig. 2
The figure is a flowchart, and FIG. 3 is a flowchart of the mold thickness inspection process.

Claims (1)

[Claims] A torque that limits the upper limit of the output torque of the servo motor of the toggle type mold clamping device, which converts the rotational motion by the servo motor into linear motion and transmits it to the crosshead of the toggle mechanism, and moves the movable platen by the toggle mechanism. In addition to providing a control device with a limit function and a sensor that detects the position of the crosshead from the rotation amount of the servo motor, a pressure receiving plate position control means is provided along with a pressure receiving plate position detector at a predetermined location, and mold clamping force is To set the mold thickness and mold clamping force, calculate and set the setting position of the pressure platen that generates the set mold clamping force from these set values, and then set the pressure platen position by the pressure plate position control means. Move the plate, and when the above set value is reached, stop the movement of the pressure plate, detect the stop position of the pressure plate, compare the detected value with the pressure plate set position above, and determine whether the value is the allowable value. If the value is within the allowable value, the mold clamping force setting process is terminated, and if it is not the permissible value, the position of the crosshead that generates the set mold clamping force is calculated, and that value is applied to the mold clamping force. An automatic mold clamping force setting method for a toggle type mold clamping device, characterized in that setting is performed as a position.