JPH1067033A - Injection molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an injection-molded product not leaving unevenness or a gate mark like a picked state and having a clean cut surface. SOLUTION: In an injection molding method injecting a molten resin into a cavity from the sprue of a mold through a gate to produce a molded product, the molded product 1 having a sprue part 15 and the gate part 21 on the root side thereof bonded thereto at a time of injection molding is demolded by mold opening. At this time, at first, the main body of the molded product 1 is allowed to slide along the slide surface 1a provided in the direction crossing the gate part 21 of the boundary of the gate part 21 and a cavity at a right angle to cut off the gate part 21 from the main body of the molded product 1 and, subsequently, an ejector pin 4 or a sleeve is operated to thrust out the sprue part 15 to separate the molded product from the mold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding method capable of obtaining a good gate cut surface.

[0002]

2. Description of the Related Art Conventionally, an injection molding method for injecting a molten resin from a gate into a cavity through a sprue to form a molded product is described in, for example, Japanese Patent Application Laid-Open No. 6-210681. Can be

In this injection molding method, molding is completed (injection of a molten resin into a cavity, filling, holding pressure, cooling).
When the molded product is released from the mold by opening the mold, the sprue that is integrally attached to the molded product main body and cutting from the molded product main body of the gate part are performed as follows. I have. That is, the sprue and the gate portion are once held by the conical short side ring, the molded product is released, the gate portion is sheared from the molded product, and then the sprue is released from the conical short side ring. It has become.

[0004]

However, in the gate cutting method using the structure of the conventional injection mold as described in Japanese Patent Laid-Open No. Hei 6-210681, the cutting mode is shown in FIG. As schematically shown in FIG. 2, the gate 300 of the sprue 200 integrally attached to the molded article main body 100 is sheared in a form in which it is forcibly cut off from the molded article 100 main body. Therefore, there is a problem that finishing is required in a post-process because unevenness and a peeled gate mark remain on the cut surface 400 and the appearance is deteriorated.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to solve these problems and to leave unevenness and peeled gate marks. In addition, the present invention provides an injection molding method capable of obtaining an injection molded product having a clean cut surface.

[0006]

According to the injection molding method of the present invention, the injection molding method for injecting a molten resin from a sprue of a mold into a cavity through a gate to form a molded product is described. When releasing the molded product having the sprue portion and the gate portion on the base side adhered by opening the mold, first, with the sprue portion fixed, the molded product main body is orthogonal to the gate portion at the boundary between the gate portion and the cavity. By sliding along the sliding surface provided in the direction, the gate portion is separated from the molded product main body, and subsequently, the ejector pin or the sleeve is operated to protrude the sprue portion and release from the mold. It is characterized by.

That is, in the injection molding method of the present invention,
At the gate side of the boundary between the gate and the cavity, a block provided with a sliding surface for sliding the surface of the molded article main body in a direction orthogonal to the gate is attached, and when the molded article main body is released from the mold, a sprue portion is provided. The fixed gate section is sheared in a direction orthogonal to the molded article body.

[0008]

In the injection molding method of the present invention, a sliding surface on which the molded article body slides in a direction perpendicular to the gate is provided on the gate side at the boundary between the gate and the cavity, and the sprue portion is fixed. First, by sliding the molded article main body along the sliding surface, the gate portion is sheared in a direction perpendicular to the surface of the molded article main body. It is possible to form a molded product having a clean finished surface free from significant cut marks and unevenness on the cut surface of the gate portion, since such a gate mark remains and the appearance does not deteriorate.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a main part showing an example of the injection molding method of the present invention. In FIG. 1, a sprue portion 15 having a gate portion 21 is integrally formed and adhered immediately before molding of a molded article 1 molded by injection of a molten resin and before release. The molded article 1 is molded by an injection mold 10 having a structure shown in FIG.

That is, in FIG. 2, a cavity 13 formed by the insert 11a of the fixed mold plate 11 and the insert 12a of the movable mold plate 12 has a runner portion 14 provided on the fixed mold plate 11 side. The molten resin passes through the sprue
And the molded article 1 is molded.

[0011] The molded article 1 which has been molded is taken out by opening the injection mold 10.
With the movement of the movable mold plate 12, the ejector pins 16 are operated to release the molded product 1 from the insert 12a of the movable mold plate 12. In the mold opening of this embodiment,
Along with the operation of the ejector pin 16, the ejector pin 4 for projecting the sprue portion 15 and the runner portion 14 is provided so as to be operated so as to be shifted in timing.

The sprue section 15 and the runner section 14
A play 41 for a time lag is provided at a rear end of the ejector pin 4 for protruding the ejector. That is, when the ejector plate 17 is operated, the operation of the ejector pin 4 is shifted with respect to the ejector pin 15 by the stroke of the play 41.

Further, the mold releasing operation of the molded article 1 after the injection molding and the cutting operation of the sprue section 15 of this embodiment will be described in detail with reference to FIG. The molded product 1 slides in the direction orthogonal to the gate portion 21 on the cavity 13 side end of the molded product 1 of the movable side mold plate 12, that is, on the gate portion 21 side of the boundary between the gate portion 21 and the cavity 13. A moving sliding surface 1a is provided. The sliding surface 1a of the molded product 1 is
It is formed by embedding the block 5 on the a side.

When the molded product 1 is released by opening the mold, the sprue portion 15 is fixed (as described above, first, the ejector pins 16 for projecting the molded product 1 are actuated, and during the time lag, the ejector pins 4 are moved). Is not operated), the molded part 1 is first slid along the sliding surface 1a in the direction orthogonal to the gate part 21 at the boundary between the gate part 21 and the cavity 13, so that the gate part 21 is moved. Separate and then ejector pin 4
Is operated, the sprue portion 15 is protruded and released from the mold.

Therefore, as described above, the gate 21
Is sheared in a direction perpendicular to the surface of the molded article 1,
As in the conventional case, the appearance of the gate marks left on the cut surface does not deteriorate and the appearance does not deteriorate, and a clean finished surface free from significant marks and irregularities on the gate portion 21 can be obtained.

[0016]

According to the injection molding method of the present invention, a sliding surface on which the molded article body slides in a direction perpendicular to the gate is provided on the gate side at the boundary between the gate and the cavity, and the sprue portion is fixed. In this state, the molded product body is first slid along the sliding surface so that the gate portion is sheared in a direction perpendicular to the surface of the molded product body. The gate marks that were smashed remain and the appearance does not deteriorate,
It is possible to form a molded product having a clean finished surface without any noticeable marks or irregularities on the cut surface of the gate portion. Therefore, it is suitable as an injection molding method.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing an example of an injection molding method of the present invention.

FIG. 2 is a sectional view showing an example of an injection mold used in the injection molding method of the present invention.

FIG. 3 is a sectional view showing a cut state of a gate portion of a molded product.

FIG. 4 is a cross-sectional view showing a cut state of a gate portion by a conventional injection molding method.

[Explanation of symbols]

 Reference Signs List 1 Molded product 1a Sliding surface 4, 16 Ejector pin 5 Block 10 Injection molding die 11 Fixed side mold plate 12 Movable side mold plate 11a, 12a Insert 13 Cavity 14 Runner section 15 Sprue section 17 Ejector plate 21 Gate section 41 Play

Claims (1)

[Claims] In an injection molding method for injecting a molten resin from a sprue of a mold into a cavity through a gate to form a molded product, a sprue portion at the time of injection molding and a gate portion on a base side thereof adhere to each other. When the molded product is released from the mold by opening the mold, the molded product body is first slid along the sliding surface provided in the direction orthogonal to the gate portion at the boundary between the gate portion and the cavity with the sprue portion fixed. The injection molding method is characterized in that the gate portion is separated from the molded article main body, and subsequently, the ejector pin or the sleeve is operated to protrude the sprue portion and release the sprue from the mold.