JP2000006201A - Gate cutting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contrive to improve the responsiveness and controllability at a gate cutting by a method wherein the positional detection of a piston is performed by adopting a servo-controllable piston and a rod sensor. SOLUTION: A block-like cylinder main body 1 incorporates both a gate cutting piston 2 and an ejecting piston in tandem. To front part of the gate cutting piston 2, a gate cutting rod 6 is connected. An ejecting rod 7 is movably inserted throughout the gate cutting piston 2 and the gate cutting rod 6. The ejecting rod 7 is connected with the ejecting piston 3 at the rear of the gate cutting piston. Between the gate cutting piston 2 and the ejecting piston 3, a position sensor 9, which detects the retreating limit and advancing limit of the ejecting rod 7, is arranged. By forming the gate cutting piston 2 into a double rod-shaped piston, the pressure receiving area of the fore and rear surfaces of which are equal to each other, the piston 2 is made to be servo- controllable. By adopting a load sensor in the gate cutting rod 6, the detection of the pisition of the gate cutting piston 2 is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gate cut device which can be used for a molding die of a recording disk such as a CD or a DVD.

[0002]

An injection mold for a recording disk, which is significantly thinner than a normal molded product, has a gate cutting cylinder at the center of the movable mold facing the sprue portion on the fixed mold side. It has a shape punch. Injection molding is performed by injecting and filling a molten resin from a sprue into a cavity. Before the molten resin is completely solidified, a punch is used to punch the center of a product with a punch for the purpose of gate cutting.

Many defective recording disks are caused by deformation or distortion of a circular inner edge formed at the center by gate cutting, and the reproduction stability of quality (birefringence, transferability, mechanical characteristics) is poor. In order to form a high product, it is necessary to improve the responsiveness and control accuracy of a gate cutting device that operates a punch.

The present invention has been conceived in order to solve the above problems, and has as its object to adopt a servo-controllable piston as a gate cut piston and to enhance the position detection of the piston by employing a rod sensor. It is an object of the present invention to provide a gate cut device having a new configuration that enables high-accuracy control, improves responsiveness and position and pressure control during gate cut, and enables multi-stage control of speed.

[0005]

SUMMARY OF THE INVENTION According to the present invention, there is provided a block-shaped cylinder body in which both a gate cut piston and a protruding piston are provided on the same axis, and a gate cut piston is provided at a front portion of the gate cut piston. In the gate cutting device in which the rod is located and the projecting rod is inserted through the gate cut piston and the gate cut rod so as to be able to advance and retreat, and the projecting rod is positioned on the projecting piston behind the gate cut piston, Are formed by the same two-rod-type piston, and are configured to be servo-controllable.

Further, in the present invention, a position sensor for detecting a retreat limit and a forward limit of the projecting rod is disposed between the gate cut piston and the projecting piston, and a position sensor is provided between the gate cut piston and the projecting piston. A position sensor for detecting the retreat limit and the forward limit of the rod is provided, and a rod sensor having a large number of magnetic members at a constant pitch in the internal axial direction is adopted as the gate cut rod. In addition, the gate cut rod is inserted into an annular sensor head provided on the cylinder body side so that the position of the gate cut piston can be detected by the gate cut rod.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawing, reference numeral 1 denotes a block-shaped cylinder main body which can be mounted on a movable platen, and has both a gate cut piston 2 and a protruding piston 3 at the center in the same axis. The cylinder 4 of the projecting piston 3 is formed in a cylindrical shape at the rear of the cylinder 5 of the gate cut piston 2 from the cylinder main body 1 so as to fit within the tip of the mold clamping piston.

The gate cut piston 2 is formed by a double rod type piston having the same pressure receiving area on the front and rear surfaces, and a gate cut rod 6 of a sensor rod having a required length is connected to the front of the piston rod 21. It is. The gate cut rod 6 and the piston rod 21 are hollow, and the protruding rod 7 is inserted therein so as to be able to move forward and backward.

The rear end of the protruding rod 7 is connected to the front end of the rod 31 of the protruding piston 3 behind the gate cut piston, so that the piston rod 31 and the piston rod 21 of the gate cut piston 2 are connected to each other. When the detector 8 attached to the protruding rod 7 approaches the main body,
A position sensor 9 including a pair of front and rear proximity switches for detecting the retreat limit and forward limit of the protruding rod 7 is provided.

The gate cut rod 6 is formed by a rod sensor having a large number of magnetic portions 6a at a constant pitch in the direction of the internal axis. The sensor head 10 that senses the magnetic body 6a is formed of an annular member provided on the cylinder closing member 11 on the cylinder body side. It is configured to protrude outside from the front end face, so that the position of the gate cut piston can be detected by the gate cut rod 6.

As shown in the drawing, the gate cutting device having such a configuration is used by mounting the cylinder body 1 between the center of the rear surface of the movable platen 40 and the tip of the mold clamping piston 50. The gate cut rod 6 and the protruding rod 7 are located with a required gap between the gate cutting punch 61 at the center of the movable mold 60 and the rear end face of the protruding pin 62 inserted into the punch. In mounting, the gate cut rod 6 and the protruding rod 7
At the tip of the screw, a cylindrical member 12 for adjusting the gap, a screw 13 and the like are screwed, so that fine adjustment of the projection size can be performed individually.

The gate cut rod 6 and the protruding rod 7
Actuation of the piston cylinders 4, to which they are connected
5, a gate cut piston 2 with a double rod type piston having the same pressure receiving area on the front and rear surfaces.
In either case, the hydraulic pressure acting on the piston is the same in either case of retreating and forward, so there is no difference in responsiveness, and although omitted in the figure, position control is provided by providing a servo valve in the circuit. And speed control, pressure control, and the like.

The servo control of the gate cut piston 2 is performed by detecting the moving position of the gate cut rod 6 and using the detected position as the detected position of the gate cut piston 2. The annular sensor head 10 provided on the gate cut rod 6
Since the magnetic body portions 6a at a constant pitch provided in the above are detected one after another in accordance with the movement of the gate cut rod 6, the speed of the gate cut piston 2 can be increased in multiple steps in combination with the responsiveness of the double rod type piston. Very high results can be obtained for gate cutting of recording disks such as CDs and DVDs that require high molding accuracy.

The relationship between the gate cut rod 6 and the sensor head 10 also requires that the sensor head 10 provided on the cylinder main body only be inserted through the gate cut rod 6, so that the apparatus becomes structurally complicated. Without
As for the projecting piston 3 and the projecting rod 7, the same as before, no change is required, and a compact configuration is possible.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an embodiment of a gate cutting device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder main body 2 Gate cut piston 3 Projection piston 4 Cylinder 5 Cylinder 6 Gate cut rod 7 Projection rod 8 Detector 9 Position sensor 10 Sensor head 11 Cylinder closing member 21 Piston rod 31 Piston rod

Claims (3)

[Claims] A gate cut piston and a projecting piston are provided on the same axis inside a block-shaped cylinder body, and a gate cut rod is located in front of the gate cut piston, and the projecting rod is gate cut. In a gate cut device in which the piston and the gate cut rod are inserted so as to advance and retreat freely, and the projecting rod is located at the projecting piston behind the gate cut piston, the gate cut piston is moved by a double rod type piston having the same pressure receiving area on the front and rear surfaces. A gate cut device characterized by being formed and configured to be servo-controllable. 2. The gate cutting device according to claim 1, wherein a position sensor for detecting a retreat limit and a forward limit of the projecting rod is disposed between the gate cutting piston and the projecting piston. . 3. A gate sensor having a plurality of magnetic members in the inner axial direction at a constant pitch is adopted as the gate cut rod, and the gate cut rod is inserted into an annular sensor head provided on a cylinder body side. 3. The apparatus according to claim 1, wherein the position of the gate cut piston is detected by the gate cut rod.
The gate cut device as described.