JPH04301421A - Mold for injection molding - Google Patents

Abstract

PURPOSE:To shorten a production dead time during exchange work at the time of the breaking of a lightening pin with a collar by enabling exchange work at the time of the breaking of the lightening pin with the collar installed to an insert fixed onto the support plate of a moving side mold for a synthetic- resin molded form from the rear of the support plate without requiring the overhauling and dismantling of the insert. CONSTITUTION:The front end section of a lightening pin 4 with a collar is projected from the cavity surface of an insert 2 while penetrating the insert 2 while a female screw 6 having a diameter larger than the diameter of the collar is screwed at the lightening-pin 4 corresponding central position of a support plate 1, to which the insert 2, into which the collar section is buried into the rear of the insert, is fixed, and the collar top face section of the lightening pin 4 is pressure-welded and fastened by using a setscrew 7 with a hexagon socket from the rear of the support plate 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to injection molding molds, particularly to the attachment of a core of a punching pin for synthetic resin injection molded products.

0002

[Prior Art] When manufacturing a synthetic resin molded product using an injection molding machine using a mold with a nest (or core), there are cases where the molded product requires small-diameter holes or “sink marks” in the molded product. When small-diameter lightening is required as a preventive measure, conventionally, a lightening pin is attached to the insert attached to the support plate (receiving plate) on the movable mold side and protrudes above the cavity surface. A hollow hole was formed in the product.

FIG. 2 shows a cutaway cross-sectional view of an example of the main part of the insert (core) having the lightening pin. 1 is a support plate (receiving plate) of a movable side mold for synthetic resin injection molded products, 2 is a core attached to the support plate 1, and 3 is a support plate for a fixed side mold (not shown) located above. A molded product formed by injecting molten resin into a cavity provided in between is shown. If a lightening hole 3a (only one hole is shown) is required in a part of this molded product, insert the tip of the collared lightening pin 4 into the insert (as shown in the figure).
It is necessary to form a hollow hole in the molded product so as to protrude above the cavity surface of the core 2. This pin 4 nest (
To fix the core to the core 2, insert the flanged pin 4 from below into the hole drilled in the insert (core) 2, as shown in the figure.
With the top surface of the collar in contact with the surface of the support plate 1, insert the insert (core) 2 through the bolt hole provided in the support plate 1.
This was done by tightening and fixing the mounting bolts 5 to the female threads on the insert (core) 2 side.

0004

[Problems to be Solved by the Invention] However, since this type of lightening pin 4 is often extremely thin, for example, about 2 to 3 mm in diameter, it is inevitable that it will break accidentally as the molding process is repeated. . In such a case, in order to replace the pin 4, after disassembling and removing the support plate 1 from the movable side mounting plate, etc., which includes a spacer block (not shown), etc., tighten the mounting bolts 5 of the insert (core) 2. It was necessary to remove it, separate it from the support plate 1, remove the damaged pin 4, replace it with a new one, and reassemble it in the reverse order of disassembly. Note that these disassembly/assembly parts are related to molded product extrusion equipment (including extrusion plates, extrusion pins, etc.) and mold cooling equipment (both not shown), so after assembly, Water leak tests are also required, which takes an extremely long time, and during this time,
A major problem was that production was interrupted.

[0005] The present invention was made in view of the above-mentioned problems in the conventional thinning pin replacement work of this type. The purpose is to provide a means for replacement without the need for removal.

[0006]

[Means for Solving the Problems] Therefore, in the present invention, the tip of the flanged lightening pin is made to penetrate through the insert and protrude onto the cavity surface thereof, and the flange is inserted into the back surface of the insert. A female thread with a diameter larger than the collar diameter is screwed into the center position of the movable side mold support plate on which this insert embedded in the mold is fixed, and which corresponds to the lightening pin, and a set screw is inserted from the back side of this support plate. The above object is achieved by using a structure in which the top surface of the flange of the lightening pin is pressed and fixed.

[0007]

[Operation] With the mold configuration as described above, pin replacement work due to breakage of the lightening pin as described above can be done by disassembling/assembling up to the movable side mold support plate without removing the insert. Since this can be done by removing/installing the set screw, the replacement work that required a large amount of man-hours and time can be completed in a short time, and production downtime can be shortened.

[0008]

EXAMPLES The present invention will be explained below based on examples. FIG. 1 shows a view corresponding to FIG. 2 of an embodiment of the main part of the insert (core) having a lightening pin according to the present invention, and FIG.
The same (equivalent) components as in are represented by the same reference numerals.

The feature of this embodiment is that the flange-shaped hollow pin 4 is fixed by a core in the conventional example shown in FIG.
At the same time as the fixing bolts 5 are tightened, they are fixed by the surface of the support plate 1 of the movable mold for synthetic resin injection molded products, whereas in this embodiment, in FIG. A female screw 6 having a diameter larger than the collar diameter of the pin 4 is screwed at the corresponding center position, and a set screw 7 with a hexagonal hole is used from the back side to press and fix the top of the collar of the pin 4. be.

Therefore, the lightening pin 4 can be replaced by simply attaching and detaching the setscrew 7 from the back surface of the support plate 1, without the need to disassemble and remove the insert (core) 2.

[0011]Although the above conventional examples and embodiments have all been explained using a single lightening pin, it goes without saying that the principles of the present invention can be applied to any number of lightening pins.

0012

As explained above, according to the present invention, when the lightening pin of the insert is broken, replacement work can be performed by replacing the mold supporting plate on the moving side without having to disassemble the insert as in the conventional case. This can be done by using a set screw from the back of the machine, significantly reducing production downtime during this period.

[Brief explanation of drawings]

FIG. 1 is a cutaway cross-sectional view of an embodiment of the main part of the insert (core) having a lightening pin.

FIG. 2 is a diagram equivalent to FIG. 1 of a conventional example.

[Explanation of symbols]

1 Support plate 2 Nesting (core) 4 Fleshing pin with brim 6 Female thread 7 Set screw

Claims (1)

[Claims] Claim 1: A movement in which the insert is fixed, in which the tip of the flanged lightening pin passes through the insert and protrudes onto the cavity surface thereof, and the collar is embedded within the back surface of the insert. At the center position corresponding to the lightening pin of the side mold support plate,
A mold for injection molding, characterized in that a female thread having a diameter larger than the diameter of the collar is screwed in, and the top surface of the collar of the lightening pin is fixed by pressure using a set screw from the back side of the support plate. .