JPH0226659Y2 - - Google Patents

Description

[Detailed explanation of the idea] (b) Industrial application fields The present invention relates to a synthetic resin injection mold.

(b) Conventional technology The use of ejector pins when ejecting synthetic resin injection molded products from a mold was disclosed in Japanese Patent Application Laid-Open No.
As seen in Publication No. 59826, this is a well-known and commonly used technique. For molded products having ribs that are deep in the mold opening direction, as shown in the same publication, it is common to provide ejection pins also for the ribs.
An example thereof is shown in FIGS. 4 to 6. In the figure, 1 is a fixed type on the cavity side, and 2 is a movable type on the core side. Reference numeral 3 denotes a molded product formed between the fixed mold 1 and the movable mold 2, and the inside thereof has a rib 4 having a depth in the mold opening direction. Reference numeral 5 designates an ejector pin support plate disposed on the movable mold 2, on which an ejector pin 6 that presses the inner surface of the outer shell of the molded product 3, an ejector pin 7 that presses the end surface of the rib 4, and a return pin 8 are fixed. There is. The tip of the ejector pin 7 is finished flat, as seen in FIG. When the mold is opened and the movable mold 2 is separated from the fixed mold 1, the fixed rod 9 hits the ejector pin support plate 5 and pushes it relatively forward as shown in FIG.
The ejection pins 6 and 7 work together to eject the molded product 3 from the movable mold 2.

The deep rib 4 described above is inherently difficult to release from the mold, but when the force of the ejector pin 7 acts on it, the area receiving the force is compressed as shown in Fig. 7, and the area is compressed. When the compressive force is transmitted in another direction and the rib 4 has a bent planar shape, the pressure acts outward on the bent portion and tends to deform the rib, as shown in FIG. 8, causing mold release. There was a problem that became extremely difficult.

(c) Problems to be solved by the invention The invention aims to minimize the deformation of the ribs due to ejection force in molded products having ribs with depth in the mold opening direction. With the goal.

(d) Means for solving the problem In the present invention, the ejection pin arranged corresponding to the rib is provided with a front pushing part facing the end face of the rib and an extension part extending along the side surface of the rib. A plurality of engagement step portions are formed on the side surface to mutually engage with the rib side surface in the ejection direction.

(E) Effect The ejection force is distributed and transmitted not only to the rib end surface but also to the rib side surface. Therefore, the ribs will not be significantly deformed due to concentration of force and will not prevent release from the mold.

(f) Examples One embodiment will be explained based on FIGS. 1 to 3.

Components that are common to those described in the "Prior Art" section are designated by the same reference numerals and will not be described further.

The feature of the present invention lies in the structure of the ejector pin 7.
That is, the ejector pin 7 has a front pushing portion 10 corresponding to the end surface of the rib 4 as well as an extension portion 11 that extends along one side of the rib 4 and reaches the inner surface of the outer shell portion of the molded product 3. On the side surface of the extension portion 11 in contact with the rib 4, a total of four engagement step portions 12 that engage with the side surface of the rib 4 in the ejection direction are provided in the axial direction of the pin 7. Of course, the number of engagement step portions 12 is 4.
It is not limited to. The back surface of the engagement step 12 is connected to the next engagement step by a slope, and has a sawtooth shape when viewed from the side. When ejecting the rib 4 using the ejecting pin 7,
The force is transmitted to the rib 4 not only from the front pushing part 10 but also from each engagement step part 12, so that the force is not concentrated in one part of the rib 4. Therefore, the bending tendency of the bent portions of the ribs 4 is very small as shown in FIG. 3, and it hardly prevents the mold from being released.

(g) Effects of the invention This invention minimizes the deformation of the ribs that occurs when ejecting deep ribs by devising the shape of the ejection pin, and achieves smooth release of the molded product with a simple configuration. can.

[Brief explanation of the drawing]

1 to 3 show an embodiment of the present invention,
FIG. 1 is a sectional view of a main part, FIG. 2 is a partial perspective view of the rib ejecting pin, and FIG. 3 is a partial front view illustrating the interaction between the rib ejecting pin and the rib during ejection. Figure 4 and below show conventional examples;
The figure is a cross-sectional view during molding, Figure 5 is a cross-sectional view when ejecting the molded product, Figure 6 is a partially cutaway perspective view showing the molded product and rib ejecting pin, and Figures 7 and 8 are the rib ejecting pin and rib. FIG. 2 is a cross-sectional view and a partial front view illustrating the interaction of FIG. 3... Molded product, 4... Rib, 7... Rib ejecting pin, 10... Front pushing part, 11... Extension part, 12... Engaging step part.

Claims (1)

[Claims for Utility Model Registration] In a molded product having ribs with depth in the mold opening direction, an ejector pin arranged corresponding to the ribs,
A front pushing part facing the end face of the rib and an extension part extending along the side surface of the rib are provided, and a plurality of stages of engagement steps are formed on the side surface of the extension part to mutually engage with the side surface of the rib in the projecting direction. injection mold.