JP2749892B2 - Gate cutting method of side gate molding die - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a gate cutting method in a molding die for performing molding by resin injection from a side gate.

[Prior art]

The side gate molding die is frequently used when performing multi-cavity molding. However, cutting of the side gate of the molded product by this die has conventionally required molding the molded product 1 as shown in FIG. The side gate is sheared by a punch 3 which is positioned on the die 2 and has a clearance of 0.01 μ or less between the side of the die 2 and the runner (sprue gate) 4 at this time. Is going. In other words, the side gate is cut by so-called push-pushing.

[Problems to be solved by the invention]

In this case, if the thickness of the side gate is 0.3 mm or more,
Since the molding resin has elasticity, the molding material enters into the clearance between the punch 3 and the die 2 at the time of cutting, and
As shown in the drawing, a burr-shaped sag 10 is formed on the molded article 1. In the case of a glass fiber-containing material, glass fibers are exposed, which hinders the assembly of parts, Glass fiber may affect the function of the assembled product. The present invention has been made in view of such a point, and an object of the present invention is to provide a gate cutting method for a side gate molding die that can cut a side gate with a smooth cut surface. To be.

[Means for Solving the Problems]

Thus, according to the present invention, the punch having an acute angle is opposed to the die receiving the lower surface of the molded product, and the side gate is pushed off between the punch and the die. The method is characterized in that the runner part whose end is placed on the die is pushed down with a push-out pin. [Operation] According to the present invention, since the side gate is cut by pressing, the cut surface can be made clean without dripping, and when such a gate cut is performed, a runner portion is formed on the die. It stays on, but is pushed down with an ejection pin. EXAMPLES The present invention will be described below in detail with reference to the illustrated apparatus.
In FIG. 4 to FIG. 4, reference numeral 7 denotes an upper mounting plate, and 70 denotes a mounting plate which is urged downward by a spring 36 with respect to the upper mounting plate 7 so that the front end surface becomes a straight having a thickness of 0.05 mm or less. The punch 3 whose tip is formed at an acute angle at its upper end is attached to the mounting plate via an elastic body 30 such as urethane foam.
It touches the lower surface of 70. The die 2 receiving the lower surface of the molded product 1 is configured such that the tip of the punch 3 abuts. When the punch 3 descends, the side gate 40 is pushed completely with the die 2. Second
In the drawing, reference numeral 33 denotes a pressing pin for pressing and holding the runner portion 4 at the time of cutting, and reference numeral 34 denotes a spring for biasing the pressing pin. When the side gate 40 is cut as described above, the runner portion 4 is in a state of being received by the die 2,
Since the runner part 4 remains on the die 2 even after the gate cut, a separate protruding pin 35 is provided, and after the gate cut is completed, the runner part 4 is driven down by driving the protruding pin 35 downward. Like that. As shown in FIG. 3, in this mold, four molded products 1 are taken out. For this purpose, the same number of punches 3 as mounting plates are used so that four side gates 40 are simultaneously cut. The elastic body 30 provided above the punch 3 is provided to absorb the variation in height of each punch 3 and protect the punch 3. In addition, as shown in FIG.
Is incorporated in a mold apparatus A provided with a molding portion B of In the figure, reference numeral 8 denotes a cylinder for driving the protruding pin 35, which allows the runner portion 4 to be pushed down in the same step as the gate cut. It is preferable that the punch 3 and the die 2 are formed of a super hard material.

【The invention's effect】

As described above, in the present invention, since the side gate is cut off by pushing, the cut surface can be made clean without dripping. For this reason, dripping is performed on a product assembled or assembled into parts. Etc., and when such a gate cut is performed, the runner part remains on the die,
This is because there is no problem in the process because it is pushed down by the ejection pin.

[Brief description of the drawings]

1 and 2 are cross-sectional views of one embodiment of the present invention, FIG. 3 is a plan view of the same, FIG. 4 is a cutaway side view of the same, FIG. 5 is a cross-sectional view of a conventional example, and FIG. FIG. 2 is an enlarged side view of a molded product having undergone gate cutting according to the above conventional method, in which 1 is a molded product, 2 is a die, 3 is a punch, and 35 is an ejection pin.

Claims (1)

(57) [Claims] 1. A punch having an acute-angled tip is opposed to a die for receiving a lower surface of a molded product, and a side gate is pushed out between the punch and the die. A gate cutting method for a side gate molding die, characterized in that a runner portion having a portion mounted on a die is pushed down with an ejection pin.