JPH02198816A - Mold - Google Patents

Abstract

PURPOSE:To prevent the generation of a burr on the gate mark of a molded product and to reduce the damage of the molding surface of a gate part and that of a punch by excluding the molten resin between the leading end part of the punch and the surface of the cavity to a sprue or the cavity at the initial stage of the advance of the punch and shearing a disc gate by the punch when the advance stroke of the punch exceeds the thickness of the gate. CONSTITUTION:A molten resin passes through a sprue 1 and a disc gate 2 to fill a cavity 3 and a punch 4 is allowed to advance before the cooling and solidification of the molten resin are advanced. The molten resin in the gate 2 flows backward to the sprue 1 when the advance of the punch 4 is started and a part thereof further flows in the cavity 3 but, when the punch 4 advances over a distance equal to or more than the thickness of the gate 2, the gate 2 is closed from the cavity 3 to stop the inflow of the molten resin to the cavity 3, and the gate 2 and the cavity 3 are perfectly separated in a mold. When the part 8 of the mold is opened and a molded product and the gates protrude, the molded product and the gate are respectively released and the disc gate mark of the molded product becomes a smoothly finished state.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a resin molding mold having a disc gate and cutting the disc gate within the mold.

2. Description of the Related Art Conventionally, this type of resin molding mold has a structure in which a disc gate 12 and a sprue 11 are connected to a cavity 13, and a punch 14 is disposed directly below the disc gate 2, as shown in FIG.

In such a configuration, after filling the cavity 13 with resin, the bunch 14 is moved forward, and the punch tip surface 1 is
Gate processing was attempted within the mold by discharging the molten resin existing between 4a and the cavity surface 15 into the sprue 11 or the cavity 13.

Problems to be Solved by the Invention However, with the above configuration, the molten resin in the cavity has already started cooling and solidifying when the punch moves forward, and the molten resin between the punch tip surface and the cavity surface flows into the sprue or the cavity. Since it is difficult to completely eliminate the chips, there are problems in that the chips remain at the gate of the molded product, or that damage to the punch tip surface and cavity surface progresses significantly due to the chips being caught in each shot. Was.

Means for Solving the Problems The technical means of the present invention for solving the above problems is a disk gate whose thickness is extended in a concave shape toward the sprue side from the cavity surface, and which is arranged opposite to the disk gate, a punch having an outer diameter smaller than the inner diameter of the disk gate and capable of advancing into the disk gate; a slug well formed at the tip of the punch; and an ejector turbine slidably disposed inside the punch. It consists of

Effect The effect of this technical means is as follows. In other words, at the beginning of the punch advance, the molten resin existing between the punch tip and the cavity surface is removed to the sprue or cavity, but when the punch advance stroke exceeds the gate thickness, the molten resin trapped inside the disk gate is removed. Further expulsion continues onto the sprue, at which point the disc gate is completely sheared by the punch.

EXAMPLE An example of the present invention is shown in FIG. 1 and will be described below. 1 is a sprue, 2 is a disk gate extending convexly from the cavity surface 5 toward the sprue side, 3 is a cavity, 4 is a sleeve-shaped punch, 6 is a slug well placed in the center of the punch 4, and 7 is a This is an ejector turbine for discharging the slag well 6.

In the state shown in this figure, the sprue 11 passes through the disk gate 2 and the cavity 3 is filled with molten resin, and the punch 4 is quickly advanced before the molten resin is cooled and solidified. When the punch 4 starts moving forward, the molten resin in the disc gate 2 flows back to the sprue, and a part of it flows back into the cavity 3.
However, when the punch 4 advances beyond the thickness of the disc gate 2, the gap between the disc gate 2 and the cavity 3 is closed by the punch 4, and the flow of molten resin from the disc gate 2 to the cavity 3 is stopped. , the disk gate 2 and cavity 3 are completely separated within the mold.

Punch 4 continues to move forward until it reaches its forward limit.
The molten resin in the disc gate 2 continues to flow to the sprue 1. Sprue 1. Disc gate 2. When the resin in cavity 3 has completely cooled and solidified, part 8 of the mold is opened, and the molded product and disc gate are projected and released from the mold separately, leaving the disc gate marks on the molded product smooth. is in a state.

FIG. 2 shows another embodiment in which the bin point gate 9 and the disk gate 2 are combined.

Effects of the Invention According to the present invention, since the disk gate is completely sheared within the mold by the punch, no flaking occurs at the gate mark on the molded product, and the punch directly contacts the mold surface that forms the disk gate portion. Moreover, since there is no possibility of pinching resin particles in the form of resin particles, the possibility of damaging the gate part mold surface and punch is greatly reduced by 11 times, which has the effect of extending the life of the mold.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a main part of a molding die according to an embodiment of the present invention, Fig. 2 is a cross-sectional view of a main part of a molding die according to another embodiment of the present invention, and Fig. 3 is a conventional molding die. FIG. 2... Disc gate, 4... Punch, 5... Cavity surface, 6... Slug well, 7... Eject turbine. Name of agent: Patent attorney Shigetaka Awano and one other person) Aji-)

Claims (1)

[Claims] a disc gate whose thickness is extended in a concave manner from the cavity surface toward the sprue; and a punch which is disposed opposite to the disc gate, has an outer diameter smaller than the inner diameter of the disc gate, and is capable of advancing into the disc gate. A molding die comprising: a slug well formed at the tip of the punch; and an ejector turbine slidably disposed inside the punch.