JPH0732421A - Injection molding machine - Google Patents

Abstract

PURPOSE:To realize an injection molding machine capable of conducting molding only by opening/closing a cavity part without actuating a clamping mechanism of a main body and having a remarkably reduced running cost and a superior durability. CONSTITUTION:A main body 3 is provided with a clamping mechanism 2 for opening/closing a cavity part 1 and a sprueless mechanism 11 for pressing a resin 9 in a sprue part 8 back to an injection nozzle part 10 before a mold release. In the main body 3, a molding block body 4 forming a part of the cavity part 1 is provided so as to move for a mold release. A block body travel drive mechanism 5 is provided on the main body 3 for moving the molding block body 4 for a mold release by a minimum distance sufficient for discharging a molded piece 6 from the cavity part 1 without opening/closing the clamping mechanism 2. At the time of molding, the cavity part 1 is opened/ closed by opening/closing the molding block body 4 in the main body 3.

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.

[0002]

2. Description of the Related Art An injection molding machine injects a resin into a cavity from an injection nozzle, holds the pressure to cool and harden the cavity, separates the cavity from a parting line, and ejects a molded product in the cavity from an ejector rod. It is to be ejected by ejecting.

In the conventional injection molding machine, one side of the parting line of the cavity is fixed and the other side is movable, and the movable side is opened and closed by a hydraulic drive device. In addition, a considerably large mold clamping mechanism is provided so that the movable side can be moved back to the fixed side to close the cavity portion at the time of molding so that the mold can be clamped with a predetermined pressure.

[0004]

In the conventional injection molding machine, as described above, the mold clamping mechanism is operated to move the movable side of the mold for each molding (one shot), and reverse the mold again. It is very difficult to manufacture the molding machine itself due to the configuration that the mold clamping drive must be performed and the molding machine itself can slide, and the clearance for sliding movement of the molding machine itself and the wear caused by the slide. This causes misalignment in various places, resulting in poor opening and closing of the cavity and mold clamping, resulting in poor durability.

Further, since the molding machine itself (movable side) is slid, a large-sized drive unit (mold clamping mechanism) is required, and since this large mold clamping mechanism is operated for each molding, running cost is increased. Very expensive.

The present invention finds a problem based on this basic idea which has been taken for granted in the past, and attempts to change the idea, whereby the running cost is remarkably reduced and the durability is excellent, and the above problem can be solved. It aims to provide a groundbreaking injection molding machine.

[0007]

The gist of the present invention will be described with reference to the accompanying drawings.

A mold clamping mechanism 2 for opening and closing the cavity portion 1
And a sprueless mechanism 11 that pushes back the resin 9 in the sprue part 8 to the injection nozzle part 10 before demolding or heats the runner part 12 or the sprue part 8 and does not harden it during molding. In a main body 3 having a hot runner mechanism for molding, a molding block body 4 forming a part of the cavity portion 1 is movably arranged in a mold-releasing manner, and the molding block body 4 is placed in the cavity portion 1. The main body 3 is provided with a block body movement drive mechanism 5 for allowing the mold clamping mechanism 2 to be released and moved without opening / closing operation for a small distance sufficient for discharging the molded product 6 to open / close the cavity portion 1 at the time of molding. Molded block body 4 in the main body 3
The present invention relates to an injection molding machine characterized by being configured to be movable by opening and closing.

[0009]

After molding, when the molded product 6 is released from the cavity portion 1, the mold clamping mechanism of the main body 3 is kept as it is, and the block body movement drive mechanism 5 is operated in this condition. Then, the molding block body 4 is separated and moved to open the cavity portion 1, and the molded product 6 in the cavity portion 1 is ejected by ejecting it with an ejector rod 7 or the like.

When performing the next molding again, the molding block body 4 is moved back by the block body movement drive mechanism 5 to close the cavity portion 1.

At the time of maintenance of the cavity 1, the mold clamping mechanism 2 of the main body 3 is operated to open the cavity 1. Therefore, opening / closing of the cavity portion 1 in a normal molding shot is performed by slidingly moving (opening / closing movable) only the molding block body 4.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a schematic structure of an injection molding machine of this embodiment to which the present invention is applied will be described with reference to the drawings.

In the drawing, reference numeral 20 is a fixed platen, 21 is a diver, and 22 is a movable platen. The movable platen 22 is provided by a mold clamping device such as a toggle so that it can be opened / closed / clamped movably to form a mold clamping mechanism 2. is doing.

A movable screw 23 is provided on the fixed platen 20 side.
An injection nozzle portion 10 for injecting the resin 9 is provided.

The resin 9 extruded from the injection nozzle portion 10 is configured to be filled in the cavity portions 1 at two places via the sprue portion 8 having a large diameter and the runner portion 12 branching.

In this embodiment, a molding block body 4 which forms a part of the cavity portion 1 is provided on the cavity portion 1 via the parting line 24 on the movable platen 22 side.
On the side of the movable platen 22 of the molding block body 4 (hereinafter referred to as the rear), a space is formed in which the molding block body 4 can be separated and moved so that the molding block body 4 can be separated and moved.

Behind the molding block body 4, a block body movement drive mechanism 5 for separating the molding block body 4 from the mold (moving forward and backward) is provided.

Further, in the illustrated embodiment, the hot runner mechanism is not used, but the sprueless mechanism 11 that pushes back the resin 9 in the sprue portion 8 to the injection nozzle portion 10 before releasing the mold is employed.

This sprueless mechanism 11 is a mechanism based on the sprueless molding method according to Japanese Patent Application No. 5-84732 invented by the applicant.

The present mechanism 11 temporarily pushes the resin 9 in the sprue portion 8 back to the injection nozzle portion 10 by the sprue push-back rod 25 before breaking the cavity portion 1 and releasing the molded product 6.

According to this method, the sprueless product can be molded and discharged, and the resin material can be saved. The tip of the sprue push-back rod 25 can be used to close the injection nozzle portion 10, and even if the injection nozzle portion 10 and the sprue portion 8 are designed to have a large diameter, resin leakage can be reliably prevented, and the sprue portion 8 can be prevented. With a large diameter, the resin 9 in the sprue part 8
Even if is in a semi-molten state, the molded product 6 does not have any problems and does not require a small diameter injection nozzle section 10, so injection resistance is low and low-pressure injection is possible, so warpage and deformation can be reduced, and molded products for each shot It becomes an excellent injection molding machine that can reduce the variation of 6 good and bad.

That is, since the sprueless mechanism 11 has the sprueless product, the sprueless product is molded. Therefore, the mold-releasing distance for the mold-releasing movement of the cavity 1 is extremely small, and the molded product 6 is dropped and discharged. It suffices to open the cavity portion 1 for a short distance sufficient for the molded product 6 to be ejected by the ejector rod 7 and to be dropped and discharged.

The open / close distance of the cavity 1 can be similarly shortened even if the runner-less product (also referred to as sprueless product) is formed by a known hot runner mechanism, but in the present embodiment, the invention of the present applicant was invented. It uses a sprueless mechanism 11.

Therefore, the features of the present invention can be utilized by the sprueless mechanism 11, and the above-mentioned operation and the excellent effect described later can be exhibited.

Next, the driving means for the block moving drive mechanism 5, the ejector rod 7 and the sprue push-back rod 25 in this embodiment will be described.

In this embodiment, an opening / closing rod 26 for separating the mold block 4 from the mold (moving back and forth) is connected to the rear of the mold block 4, and the ejector rod 7 and the sprue push-back rod 25 are arranged coaxially. The block body movement drive mechanism 5 constituted by a hydraulic cylinder device capable of performing hydraulic pressure switching control by the same cylinder controls movement.

In the figure, reference numeral 27 is an ejector plate on which the opening / closing rod 26 is projected, 28 is an ejector plate on which the ejector rod 7 is projected, 29 is an ejector plate on which the sprue push-back rod 25 is projected, and each ejector plate 27, Connecting rods 30, 31 and 32 are projected rearward to 28 and 29, and the connecting rods 30, 31 and 32 are respectively connected to the three hydraulic chambers 33 of the hydraulic cylinder device 5A of the block body movement drive mechanism 5.
It is distributed to 34 and 35. Therefore, in this embodiment, the molding is performed from the mold clamping state shown in FIG. 1 to the state where the molded product 6 shown in FIG.

First, when oil is injected into the third hydraulic chamber 35,
The sprue push-back rod 25 advances through the connecting rod 32 and the ejector plate 29 to push the resin 9 in the sprue portion 12 back to the injection nozzle portion 10. This realizes the sprueless molding method described above.

Next, when oil is injected into the first hydraulic chamber 33, the opening / closing rod is connected via the connecting rod 30 and the ejector plate 27.
26 is pulled, the molding block body 4 is separated and moved rearward by a predetermined small distance, and the cavity portion 1 is opened from the parting line 24.

Finally, oil is injected into the second hydraulic chamber 34, and the ejector rod 7 is pushed forward through the connecting rod 31 and the ejector plate 28, so that the molded product 6 in the cavity portion 1 of the molding block body 4 is removed. Stick out, drop and eject.

In this way, as shown in FIG.
After discharging, the molding block body 4 is returned to its original position and moved to close the cavity portion 1 by performing the reverse operation described above, and molding is performed again.

As described above, in the normal molding, the mold clamping mechanism 2 is not operated at all, and the mold block 4 is moved by opening and closing by a minimum required minimum distance while maintaining the mold clamped state. Emission can be realized.

[0033]

As described above, the present invention is an injection molding machine having a sprueless mechanism or a hot runner mechanism that pushes the resin in the sprue portion back to the injection nozzle portion before releasing the mold. The structure is sufficient if it is moved within a small distance for discharging the molded product in the cavity portion. Therefore, by applying the present invention to the injection molding machine having such a structure, the cavity for normal molding To open and close the tee part, it is sufficient to open and close only the molding block inside the main body for a small distance.Therefore, a large mold clamping mechanism that opens and closes the molding machine itself more than the parting line for each molding is required. It is not necessary to operate it, so it is difficult for the deviation due to this operation to reach the cavity, thus improving durability and running cost. And thus be significantly reduced.

Further, since the movable stroke of the molding block body is sufficient if it is moved by a small distance allowing the molded product to be ejected and discharged, from this point of view also, the accuracy of the cavity portion is maintained and durability is improved. improves.

Further, the durability of the mold clamping mechanism itself, which is not movable for opening and closing for each molding, is also improved.

[Brief description of drawings]

FIG. 1 is an explanatory plan sectional view at the time of molding with a cavity portion closed in the present embodiment.

FIG. 2 is an explanatory plan sectional view when a cavity is opened and a molded product is dropped and discharged in the present embodiment.

[Explanation of symbols]

 1 cavity part 2 mold clamping mechanism 3 main body 4 molding block body 5 block body movement drive mechanism 6 molded product 7 ejector rod 8 sprue portion 9 resin 10 injection nozzle portion 11 sprueless mechanism 12 runner portion

Claims (1)

[Claims] 1. A sprueless mechanism which has a mold clamping mechanism for opening and closing a cavity portion and pushes back the resin in the sprue portion to the injection nozzle portion before releasing the mold, or a runner portion which does not cure by heating the runner portion or the sprue portion. In a main body having a hot runner mechanism for forming a molded product of a spearless or sprueless structure, a molding block body forming a part of this cavity portion is movably arranged in a mold release manner, and the molding block body is placed in the cavity portion. The main body is equipped with a block body movement drive mechanism that allows the mold clamping mechanism to be released and moved without opening and closing for a small enough distance to discharge the molded product. An injection molding machine characterized by being configured such that the body can be opened and closed.