JPH11147240A - Device for controlling mold clamping pressure in molding machine for synthetic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely control a mold clamping pressure to a predetermined value when a pair of dies provided between a movable head reciprocating along a plurality of guide rods interconnecting a base plate head and a fixed head and the fixed head are to be clamped by advancing motion of the movable head by means of a reciprocating mechanism. SOLUTION: A sensor 8 is provided on at least one guide rods 2 to sense an elongation strain in the guide rod in the axial direction, and the advancing motion of a movable head toward a fixed head caused by a reciprocating mechanism is stopped based on a sensing signal at the sensor 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling the pressure at which both dies are joined together and then clamped in a synthetic resin injection molding machine or transfer molding machine.

[0002]

2. Description of the Related Art In general, a synthetic resin injection molding or transfer molding machine is well known in the art, and as described in, for example, Japanese Patent Application Laid-Open No. 7-308934, a base head and a fixed head are used. Are connected by a plurality of guide rods, and a movable head configured to reciprocate freely along each guide rod is provided between the base head and the fixed head, And a pair of molds are disposed between the movable head and the movable head, such that one mold of the pair of molds is fixed to the fixed head side and the other mold is fixed to the movable head side. A hydraulically operated or electric motor operated reciprocating mechanism is provided between the base head and the movable head, so that the movable head is moved forward or backward or reciprocated toward the fixed head. , This reciprocating machine By moving the movable head forward toward the fixed head, a pair of molds are aligned with each other and then clamped at a predetermined pressure. In this clamped state, a concave is formed in the mating surface of the two molds. The synthetic resin is injected into the formed cavity in a molten state.

[0003] In this case, conventionally, when the reciprocating mechanism of the molding machine is a hydraulically operated type, the pressure of the hydraulic pressure is regulated to a predetermined value when the two dies are clamped, so that a predetermined value is obtained. And when the reciprocating mechanism in the molding machine is an electric motor-operated type, the output torque of the electric motor is regulated to a predetermined value when both molds are clamped. Thereby, a predetermined mold clamping pressure is obtained.

[0004]

However, in the former system using hydraulic pressure, the mold clamping pressure is set to be the same for each molding performed many times due to the existence of hydraulic leakage in various hydraulic lines and hydraulic valves. Cannot be aligned to the value,
Since the clamping pressure varies for each molding, large variations occur in the quality such as dimensions and shapes between the synthetic resin molded products. However, there is a problem that the durability is reduced.

On the other hand, in the latter electric motor operated type molding machine, the mold clamping pressure in both dies is affected by the dimensional change due to the temperature in both dies, so that the former does not change unless the temperature of both dies is changed. On the other hand, the regulation value of the output torque when the molds are clamped must be finely corrected so as to increase or decrease in accordance with the temperature in the molds. A lot of trouble,
There is a problem that requires a high degree of skill.

An object of the present invention is to provide a mold clamping pressure control device which solves these problems.

[0007]

SUMMARY OF THE INVENTION To achieve this technical object, the present invention provides a plurality of guide rods for connecting a base head and a fixed head, and each guide between the base head and the fixed head. A movable head disposed so as to reciprocate freely along a rod, and a pair of dies between the fixed head and the movable head, and one of the dies between the pair of dies. A synthetic resin having a reciprocating mechanism for reciprocating the movable head between the base head and the movable head, while the other mold is fixedly disposed on the movable head side on the fixed head side. In the molding machine, at least one of the guide rods,
A sensor for detecting an axial extension strain of the guide rod is provided, and the reciprocating mechanism stops moving the movable head toward the fixed head based on a detection signal from the sensor. And Is the thing.

[0008]

The guide rod connecting the base head and the fixed head has a pulling force as the movable head is moved forward in the direction of the fixed head by a reciprocating mechanism to clamp both molds. , Each of the guide rods is stretched and distorted in the axial direction thereof, and the extensional strain in the axial direction is proportional to the mold clamping pressure of both molds.

Therefore, as described above, at least one of the guide rods is provided with a sensor for detecting an axial elongation distortion of the guide rod, and the reciprocating movement is performed based on a detection signal from the sensor. By configuring the movable head to stop moving forward in the direction of the fixed head by the mechanism, the mold clamping pressure on both the dies is determined by the amount of elongation distortion of the guide rod at which the mold clamping pressure acts as a tensile force. It can be regulated.

[0010] The extension strain of the guide rod is:
This occurs when the two dies are clamped, and this amount of elongation strain does not change due to leakage of hydraulic pressure. Since the factors are included, the mold clamping pressure for both molds can be accurately controlled to a predetermined value without requiring fine adjustment.

Therefore, according to the present invention, it is possible to greatly reduce the number of steps required to set the mold clamping pressure for both the dies, to achieve uniformity in quality such as size and shape between the synthetic resin molded products, and to obtain both molds. The durability of the mold can be improved, and furthermore, it is only necessary to provide the guide rod with a sensor for detecting the extension strain in the axial direction.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 and 2 showing a vertical molding machine. In this figure, reference numeral 1 indicates a base head installed on the ground, and a plurality of base heads 1 (normally,
At the upper end of each of the four guide rods 2)
The fixed head 3 is fixed.

Reference numeral 4 denotes a movable head disposed between the base head 1 and the fixed head 3. The movable head 4 is guided so as to freely reciprocate along the guide rods 2. ing. Between the movable head 4 and the fixed head 3, a pair of dies 5, 6 is placed. The molds 6 are disposed so as to be fixed to the movable head side.

A hydraulically operated or electric motor is provided between the base head 1 and the movable head 4 so as to move the movable head 4 forward, backward, or reciprocate toward the fixed head 3. An actuated reciprocating mechanism 7 is provided. That is, by moving the movable head 4 forward toward the fixed head 3 by this reciprocating mechanism, as shown by a two-dot chain line in FIG. Clamp the mold with pressure.
The synthetic resin is injected in a molten state into the cavities 5a and 6a formed in the mating surfaces of the two dies 5 and 6.

At least one of the guide rods 2 is provided with a sensor 8 for detecting an axial elongation distortion of the guide rod 2, and based on a detection signal from the sensor 7, The reciprocating mechanism 8 stops moving the movable head 4 in the direction of the fixed head 3. The reciprocating mechanism 7
The lower die 6 of the movable head 4 moves the fixed head 3
After contact with the upper mold 5 in these two molds 5, 6
Are clamped together. At this time, a pulling force acts on each guide rod 2 connecting the base head 1 and the fixed head 3 as the molds 5 and 6 are clamped by the reciprocating mechanism 7, so that each guide rod 2 2 is
This results in an elongation strain in the axial direction, and the elongation strain in the axial direction is proportional to the clamping pressure of the two dies 5 and 6.

Therefore, as described above, at least one of the guide rods 2 is provided with the sensor 8 for detecting an axial elongation distortion of the guide rod 2, and the control circuit 9 controls the sensor 8 by using the sensor 8. 8, the forward movement of the movable head 4 in the direction of the fixed head 3 by the reciprocating mechanism 7 is stopped, that is, as shown in the flowchart of FIG. When the mold clamping of the dies 5 and 6 is started, the extension strain of the guide rod 2 is detected in step S2, and then the mold clamping pressure is calculated from the detected extension strain in step S3.
Then, in step S4, it is determined whether or not the mold clamping pressures of both the dies 5 and 6 are equal to a predetermined value.
When the mold clamping pressure is at a predetermined level, the mold clamping operation, that is, the forward movement of the movable head 4 by the reciprocating mechanism 7 is stopped, so that the two molds 5 and 5 are stopped.
6 can be regulated by the amount of elongation distortion of the guide rod 2 at which the mold clamping pressure acts as a tensile force.

In this case, each of the guide rods 2
Is generated when the molds 5 and 6 are clamped, and the amount of elongation strain does not change due to leakage of hydraulic pressure. Since it includes a factor of dimensional change due to temperature in both dies 5, 6, the mold clamping pressure on both dies 5, 6 is accurately controlled to a predetermined value without requiring fine adjustment. You can do it.

In the above-described embodiment, the sensor 8 for detecting the extension and distortion of one of the plurality of guide rods 2 is provided. Not limited to this, it is needless to say that the control may be performed based on the average value of the elongation strain of two or more guide rods 2 located on the left and right sides of both dies 5 and 6 among the respective guide rods 2. Thereby, the mold clamping pressure of both molds can be made uniform over the entire surface of both molds.

The present invention can also be applied to a horizontal molding machine, and it goes without saying that the present invention can be applied to a synthetic resin injection molding machine and a transfer molding machine.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a diagram showing a flowchart of control.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base head 2 Guide rod 3 Fixed head 4 Movable head 5 Upper mold 6 Lower mold 7 Reciprocating mechanism 8 Sensor 9 Control circuit

Claims (1)

[Claims] 1. A plurality of guide rods for connecting a base head and a fixed head, and a movable head disposed between the base head and the fixed head so as to freely reciprocate along each guide rod. Between the fixed head and the movable head, a pair of dies, one of the pair of dies is fixed to the fixed head side and the other is fixed to the movable head side. On the other hand, in a synthetic resin molding machine provided with a reciprocating mechanism for reciprocating the movable head between the base head and the movable head, at least one of the guide rods includes A sensor is provided for detecting an axial elongation distortion of the guide rod, and the forward movement of the movable head toward the fixed head by the reciprocating mechanism is stopped based on a detection signal from the sensor. A control device for controlling a mold clamping pressure in a synthetic resin molding machine, characterized in that it is configured as described above.