JPH05104593A - Injection molding machine - Google Patents

Abstract

PURPOSE:To hold an ejector pin by using an ejector plate, which has simple structure and cost of which is low, by providing the ejector plate with an attracting means attracting the base end of the ejector pin by magnetic force. CONSTITUTION:A molding material is injected from a gate 16 under the state, in which a fixed side mold 13 and a movable side mold 22 are closed, and injected between a recessed section 15 and a projecting section 26 through a runner 18 and molded. An ejector rod 32 is moved in the direction of the arrow B by a driving source, and an ejector plate 28 is pushed in the same direction. Accordingly, since the base end of an ejector pin 33 is attracted by the magnetic force of a magnet 34 fixed to the ejector plate 28, the usage of two ejector plates and boring working are unnecessitated for holding the ejector pin 33, structure is simplified and cost is reduced. A diametral expanding section need not also be formed to the base end of the ejector pin 33.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding machine having a mold releasing means having a simple structure for releasing a molded product from a mold.

[0002]

2. Description of the Related Art A fixed-side mold having a concave portion and a movable-side mold having a convex portion are arranged so as to face each other, and a plastic material heated to be a fluid is injected between the concave portion and the convex portion. When molded into a predetermined shape, the molded product shrinks when cooled after molding. For this reason, the molded product bites on the convex portion of the movable side mold, and it becomes difficult to release the molded product. In order to facilitate the mold release, the injection molding machine is usually provided with an ejector pin for pushing out a molded product from the movable side mold.

FIG. 2 shows a conventional ejector pin mounting structure. An enlarged diameter portion 1a is formed on the base end side of the ejector pin 1, and the enlarged diameter portion 1a is provided with two ejector plates 2a.
It is held between a and 2b to prevent the ejector pin 1 from falling off the ejector plate 2. That is, the one ejector plate 2a is formed with the through hole 3 into which the ejector pin 1 is inserted and the spot facing portion 4 in which the expanded diameter portion 1a is housed. Then, a pair of ejector plates 2a and 2b integrate the ejector pin 1 while holding the base end of the ejector pin 1 and drive the ejector plate 2 forward and backward by a drive means (not shown) to release a molded product (not shown) from the mold. ing.

[0004]

However, according to the mounting structure of the conventional ejector pin 1 to the ejector plate 2 shown in FIG. 2, two ejector plates 2 are required, and one ejector plate 2a has a hole and a seat. There has been a problem that the boring process has to be carried out and the cost becomes high. Further, since the positions of the through hole 3 and the spot facing portion 4 change depending on the shape of the molded product, it is necessary to prepare the ejector plate 2 corresponding to the type of the molded product. Further, it is necessary to perform a process for forming the expanded diameter portion 1a on the base end of the ejector pin 1.

The present invention has been made in view of such circumstances, and an object thereof is to provide an injection molding machine having a simple and inexpensive ejector pin holding structure.

[0006]

An injection molding machine according to the present invention has a fixed-side mold, a movable-side mold provided so as to face the fixed-side mold, and a movable-side mold so as to be freely retractable. In an injection molding machine equipped with an ejector plate that separates a molded product molded between a pair of molds from a movable mold and an ejector plate that holds the base end of the ejector pin and moves back and forth, It is characterized in that a suction means for suctioning the base end of the ejector pin by magnetic force is provided.

[0007]

In the structure of the injection molding machine of the present invention, since the base end of the ejector pin is suction-held by the suction means provided on the ejector plate, the ejector plate has only one unit.
Only a single sheet is required, and the processing is easy. Also, since different types of molded products can be used, the degree of freedom in designing the ejector plate is also improved. Further, it is not always necessary to provide the enlarged diameter portion at the base end of the ejector pin.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the injection molding machine of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, a fixed-side die 13 is attached to a fixed-side attachment plate 11 fixed to a fixed-side platen (not shown) via a plurality of bolts 12. A concave portion 15 for molding one surface of the molded product 14 is formed at the center of the front surface of the fixed-side die 13, and a sprue 16 is fixed to the outer center of the fixed-side mounting plate 11 via a screw 17. .. Further, the fixed-side mounting plate 11 and the fixed-side mold 13 include a sprue 16 and a recess 15
A hot water passage 18 is provided to communicate with and.

On the other hand, a movable side mold 22 is attached to a movable side mounting plate 19 fixed to a movable side platen (not shown) via a spacer block 20 and a movable side receiving plate 21. The movable side mounting plate 19, the spacer block 2
0, the movable-side receiving plate 21, and the movable-side mold 22 are integrally fixed via a plurality of bolts 23. Further, the movable mold 22 is provided with a plurality of bushes 24, and the guide pins 25 implanted in the fixed mold 13 are inserted,
The movable die 22 is positioned with respect to the fixed die 13. Further, a convex portion 26 is formed at a position aligned with the concave portion 15 on the surface of the movable side die 22 facing the fixed side die 13.

Further, the movable mold 22 and the movable support plate 21 are provided with a plurality of columns 2 in a direction perpendicular to their respective surfaces.
7 is slidably mounted. In addition, the support 27 is the receiving plate 2
An ejector plate 28 is attached to the tip protruding from 1 in parallel with the receiving plate 21 via a screw 29.
The ejector plate 28 is biased in the direction indicated by the arrow A by a coil spring 30 wound around the column 27,
The moving end of the ejector plate 28 is restricted by a stopper 31 provided on the movable side mounting plate 19. Further, the ejector plate 28 is advanced and retracted by a drive source (not shown) via the ejector rod 32.

The movable side receiving plate 21 and the movable side mold 22 are
A plurality of ejector pins 33 are slidably inserted through through-holes formed in parallel with the support columns 27, and the tips of the ejector pins 33 can project from the convex portions 26 of the movable mold 22.
A magnet 34, which is a feature of this embodiment, is fixed to the surface of the ejector plate 28 facing the movable-side receiving plate 21, and the base end of the ejector pin 33 is attracted by the magnetic force of the magnet 34.

Next, the operation of this embodiment will be described. The sprue 16 with the fixed mold 13 and the movable mold 22 closed
The molding material is injected from the mold and injected through the runner 18 between the concave portion 15 and the convex portion 26 to perform molding. When the cooling process after molding is completed, the movable side mold 22 moves in the direction of arrow A to open the mold. Next, the ejector rod 32
Moves in the direction of arrow B by a drive source (not shown) and pushes the ejector plate 28 in the same direction. As a result, the ejector pin 33 is also pushed in the same direction, the tip of the ejector pin 33 projects from the convex portion 26 of the movable-side die 22, and the molded product 14 is ejected. When the ejector rod 32 retracts and the ejector plate 28 moves in the direction of arrow A by the urging force of the coil spring 30 mounted between the ejector plate 28 and the movable side receiving plate 21, the ejector pin 33
The base end of the magnet 34 is fixed to the ejector plate 28.
Since it is adsorbed by the magnetic force of 1, the magnets retreat together in the same direction and the next molding step is prepared.

According to this embodiment, since the base end of the ejector pin 33 is attracted by the magnetic force of the magnet 34 fixed to the ejector plate 28, the two ejector plates 28 are held to hold the ejector pin 33. There is no need to use or drill holes, and the structure is simple and the cost is low. Further, it is not necessary to provide a diameter expansion portion at the base end of the ejector pin 33. Furthermore, since the base end of the ejector pin 33 can be held at any position of the magnet 34, the same ejector plate 28 can be used when molding different types of molded products, and the setup time can be shortened.

In the above embodiment, the magnet 34 is used as the attracting means for the ejector pin 33, but the magnet 34 may be an electromagnet. In this case, the timing and time for generating the magnetic field, the strength of the magnetic force, and the demagnetization can be arbitrarily adjusted. Also ejector pin 33
If the diameter is small and sufficient suction force cannot be obtained, a diametrically expanded portion may be provided at the base end.

[0016]

As described above, according to the injection molding machine of the present invention, since the ejector plate is provided with the adsorbing means for adsorbing the base end of the ejector pin by magnetic force, an inexpensive ejector plate having a simple structure is provided. The ejector pin can be held by using it and the setup time can be shortened.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a configuration of an embodiment of an injection molding machine of the present invention.

FIG. 2 is a vertical cross-sectional view showing a configuration of an example of a conventional connecting portion between an ejector pin and an ejector plate.

[Explanation of symbols]

 13 Fixed-side mold 14 Molded product 22 Movable-side mold 28 Ejector plate 33 Ejector pin 34 Magnet (adsorption means)

Claims (1)

[Claims] 1. A fixed-side mold, a movable-side mold that is provided so as to face the fixed-side mold, and a movable-side mold that is inserted into the movable-side mold so as to be movable back and forth, and is molded between the pair of molds. In an injection molding machine comprising an ejector pin for releasing the molded product from the movable side mold, and an ejector plate for advancing and retracting while holding the base end of the ejector pin, the ejector plate has a base end of the ejector pin. An injection molding machine, characterized in that it is provided with a suction means for sucking by a magnetic force.