JPH0129060Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Field of industrial application The present invention relates to a mold device for injection molding synthetic resin, etc.

(b) Prior art Undercuts are often formed in injection molded products. The molded product 1 shown in FIG. 1 is shaped like a container, and the bottom surface (facing upward in the figure) is provided with a recessed part 2 that is recessed inward.
A protrusion 3 rises outward from the base, and a protrusion 4 is formed on the side surface of the protrusion 3. The protrusion 4 is undercut with respect to the mold opening direction. Such undercuts must be treated with a cavity mold. For example, a structure in which a sliding member for forming an undercut part is provided in a cavity mold is proposed by Tokuko Showa.
This can be seen in Publication No. 53-11298 and Publication No. 16660 of Sho 55-1. However, all of the structures described in these documents have a structure in which the slide member approaches or moves away from the molded product from the side, and as in molded product 1, the protrusion extends from the recessed part on the bottom surface. It could not be applied as is to a product that stands upright and has an undercut on the side surface of the protrusion because the presence of the recess would be a hindrance.

(C) Purpose of the invention The invention has a container-like shape as a whole, and has an inwardly recessed part on the bottom surface, and from the recessed part,
It is an object of the present invention to provide an injection molding die that enables molding of a molded product in which a protrusion having an undercut portion on the side surface rises outward.

(d) Structure of the invention In this invention, a cavity is provided in the cavity mold at a location behind the cavity when viewed from the core mold, and a mold is slidable in the mold opening direction into this cavity. , and a movable plate biased by a spring in the direction of the core mold. A slide piece that can slide in a direction perpendicular to the mold opening and is guided by an angular pin is attached to this movable plate, and an oblique slide core whose tip projects into the cavity portion is fixed to this slide piece. The diagonal slide core forms a part of the recess on the bottom of the molded product and the undercut side surface of the protrusion rising from the recess. Further, the movable plate is provided with a return pin so that when the mold is closed, this pin hits the core mold and pushes the movable plate back.

(E) Embodiment This will be explained based on FIG. 2 and subsequent figures. 10 is a mold device for molding the molded product 1 shown in FIG. 1;
It consists of a fixed block 11 and a moving block 12 (only the main parts are shown in the figure). The main body of the fixed block 11 is a cavity mold 13, and the main body of the movable block 12 is a core mold 14. Inside the cavity mold 13, there is a vacant space 16 at a position behind the cavity part 15 when viewed from the core mold 14.
is provided. A movable plate 17 is housed in this empty space 16. The movable plate 17 is guided by guide pins 18 shown in FIG. 3 and slides in the mold opening direction. 1
9 is a spring that biases the movable plate 17 toward the core mold. 20 is a return pin fixed to the movable plate 17, which passes through the cavity mold 13 and returns to the core mold 1.
4, and when the mold is closed, it hits the core mold and pushes back the movable plate 17 against the spring 19. A slide piece 21 is attached to the movable plate 17 and is slidable in a direction perpendicular to the opening of the mold. In the case of the embodiment, the sliding direction is the direction in which the protrusion 4 of the molded product 1 faces. The slide piece 21 is guided by an angular pin 22 protruding from the cavity mold 13 and slides. A diagonal slide core 23 extends in the same direction as the angular pin 22, passes through the cavity mold 13, has a base end fixed to the slide piece 21, and a distal end enters the cavity portion 15. This diagonal slide core 23 includes a part of the concave part 2 and a part of the protrusion 3.
The shape of the side surface with the protrusion 4 is molded.

When injection molding is performed using the above-mentioned mold apparatus and the mold is opened, as the core mold 14 moves away from the cavity mold 13, the movable plate 17 also slides in the same direction. At the same time, the slide piece 21 is laterally displaced by the angular pin 22, and the diagonal slide core 2
3 extends diagonally. Therefore, the diagonal slide core 23 gradually separates from the protrusion 3, and when the movable plate 17 reaches the inner wall of the cavity 16 and stops sliding as shown in FIG. The molded product 1 is completely removed from the cavity and moves away from the cavity mold 13 without any obstruction.

(f) Effects of the invention In this invention, since the diagonal slide core approaches the molded product from the bottom in the cavity, the bottom has a recess, and from the recess, a protrusion with an undercut side surface is formed. It has become possible to form molded products that look like they are standing up.

[Brief explanation of drawings]

Fig. 1 is a partial cross-sectional view of a molded product to be molded with the mold of the present invention, Fig. 2 is a partial cross-sectional view showing an embodiment of the present invention, and Fig. 3 is a cross-section taken in a direction perpendicular to Fig. 2. FIG. 4 is a partial sectional view similar to FIG. 2 showing different operating conditions. 11... Fixed side unit, 12... Moving side unit, 13... Cavity mold, 14... Core mold, 15... Cavity part, 16... Vacant room, 17
...Movable plate, 21...Slide piece, 22...
Angular pin, 20...Return pin, 23
...Diagonal slide core, 1... Molded product, 3... Protrusion.

Claims (1)

[Scope of Claim for Utility Model Registration] A cavity mold constituting a stationary unit and having a vacant space behind the cavity when viewed from the core mold, and a cavity mold that is housed in the vacant space and slides in the mold opening direction. a movable plate that is movable and biased by a spring in the direction of the core mold; a slide piece that is mounted on the movable plate so as to be slidable in a direction perpendicular to the mold opening; and a slide piece that protrudes from the cavity mold; an angular pin that engages with and guides the slide piece; a return pin that is fixed to the movable plate and hits the core mold when closing the mold and pushes back the movable plate against the applied force; A diagonal slide core that is fixed to the slide piece and whose tip protrudes into the cavity, and which forms part of the recess on the bottom of the molded product and the undercut side surface of the protrusion that rises from the recess. Injection mold with.