JPS6126024Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a device for preventing drooling that occurs during injection molding of synthetic resin.

In injection molding, when the nozzle is separated from the mold,
Since residual pressure exists in the molten resin stored at the tip of the injection screw, resin may leak from the nozzle. Generally, this resin leakage is called drooling, and as a method to prevent this, the injection screw is forced to retreat slightly after metering is completed to relieve the resin pressure in the injection cylinder.

However, in this method, if the backward stroke of the injection screw is too long, negative pressure will develop in the injection cylinder, which will cause air to enter from the air nozzle. This air enters the mold together with the molten resin during the next injection, causing defects in the molded product.

Therefore, limit switches and photoelectronic switches are used to regulate the backward stroke of the injection screw, but each time the metering stop position is changed depending on the material resin or molded product, the backward stop position must also be adjusted. I had to. This position adjustment is not only troublesome in the molding operation, but also difficult to set at the proper position at once, so if left unadjusted, there is a tendency for the backward stroke to be insufficient or for the reverse stroke to be too far. There are some methods that detect the position of the injection screw using an encoder, etc., and calculate the decompression stop position, but they are expensive and lack versatility, so they are not widely used unless they are incorporated into process control. It has not been.

This idea was conceived based on the above-mentioned considerations, and is capable of completely regulating the stroke of secondary retraction following metering due to the rotational retraction of the injection screw, and also because of its positional relationship with the metering completion position. In this connection, we propose a drool ring prevention device with a new structure that can reliably adjust the retracted position of the injection screw to a predetermined stroke to prevent drool ring.

This invention will be explained in detail below using illustrated examples.

1 is the outer edge of the window on the side of the injection device on the main body 2
It is installed. A main screw shaft 3 arranged parallel to the injection screw A is rotatably installed in the lower part of the main body 1, and a slider 4 is attached to the main screw shaft 3.

This slider 4 is in contact with a guide protrusion 5 fixed to the main body side and moves on the screw shaft in either the left or right direction by the rotation of the main screw shaft 3, and has a base that meshes with the main screw shaft 3. Arms 6, 6 are provided on both sides of 4a, and a mounting plate 7 is integrally provided over the arms 6, 6. In addition, a sub-screw shaft 8 parallel to the main screw shaft 3 is rotatably mounted on the lower part of the arms 6, 6. A movable element 9 that moves horizontally is attached.

10 is a measurement completion position detector attached to the mounting plate 7, and 11 is a retreat position detector of the injection screw A for the drool ring prevention device attached to the movable element 9. It consists of a proximity switch, a photoelectronic switch, etc., which are installed through each child 9.

A detection plate 12 is held by a guide 14 so as to move forward and backward together with the injection screw A via a transmission plate 13, and the position of this detection plate 12 is electrically detected.
Generates an electrical signal for the metering completion or retreat position detector.

The position of the metering completion position detector 10 is adjusted by rotating the main screw shaft 3, and the position is determined by a digital counter 15 provided on the side of the main body. Further, the position of the backward position detector 11 is adjusted by rotating the auxiliary screw shaft 8, and its position is determined using the center of the metering completion position detector 10 as a reference point.

Therefore, since both detectors move equally when the main screw shaft 3 rotates, if the end point position of the backward stroke based on the measurement completion position is determined by the rotation of the subscrew shaft 8, the measurement can be performed later. Even if the completion position has to be adjusted, the retracted position to prevent drooling may remain as it is.

As mentioned above, this device has a main screw shaft 3 which is rotatably installed in the main body 1, and a slider 4 in which a sub-screw shaft 8 parallel to the main screw shaft 3 and a mounting plate 7 are arranged vertically in parallel.
, and fix the metering completion position detector 10 to the mounting plate 7 of the mover 4. At the same time, attach the mover 9 retraction position detector 11 of the subscrew shaft 8, so that the metering completion position detector 10 and the retraction position detector 10 are fixed. Since the position detector 11 is configured to always move at equal intervals and at the same time, there is no need to adjust the retreat position every time the measurement completion position is changed, unlike in the conventional case. In addition, since the retracting position can be freely adjusted using the secondary screw shaft, the distance from the metering completion position is not constant, and the retracting stroke can be adjusted to the length most suitable for preventing drooling. Furthermore, all adjustments are made by rotating the screw shaft, making fine adjustments easy.
It has features such as being able to perform highly accurate adjustments.

[Brief explanation of the drawing]

The drawings illustrate the drooling prevention device according to the invention, with FIG. 1 being a longitudinal sectional view and FIG. 2 being a front view. 1...Main body, 3...Main screw shaft, 4...Scillator,
5... Guide protrusion, 6... Arm, 7... Mounting plate,
8...Subscrew shaft, 9...Mover, 10...Measuring completion position detector, 11...Retreat position detector.

Claims (1)

[Scope of utility model registration request] A drooling prevention device for an injection machine, in which a movable element is attached to a main screw shaft rotatably mounted on a main body, and a secondary screw shaft parallel to the main screw shaft and an attachment part are arranged side by side above and below, a metering completion position detector is fixed to the attachment part of the movable element, and a retraction position detector is attached to the movable element of the secondary screw shaft, so that the metering completion position detector and the retraction position detector are moved simultaneously by the main screw shaft.