JPH0153165B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an injection molding machine, and in particular to an injection molding machine in which an upper mold is detachably attached to the tip of an injection unit, and a mold clamping cylinder is connected to the injection unit. It is something.

Conventionally, a synthetic resin injection molding machine as shown in FIG. 1 has been known. That is, a rotary table 2 is rotatably mounted on a frame 1, and tie bars 3 are provided passing through the frame 1, and one of the tie bars 3 3a is connected to the rotation center axis of the rotary table 1. It's summery. An upper mold plate 4 is attached to the upper end of the tie bar 3, and a cross plate 5 is attached to the lower end.
A mold clamping cylinder 6 mounted on the lower part of the frame 1 is connected to the cross plate 5. A plurality of lower molds 7 are installed on the rotary table 2, while an upper mold 8 is attached to the lower part of the upper mold plate 4.

Further, a support 9 is erected on the upper mold plate 4, and an injection unit mounting plate 10 is mounted on the support 9.
is slidably fitted. An elevating cylinder 11 provided on the upper mold plate 4 is connected to the mounting plate 10. An injection unit 12 is attached to the mounting plate 10, and its heating cylinder 13 can penetrate the upper mold plate 4 and come into contact with the upper mold 8.

In the above-mentioned prior art, the upper mold 8 is attached to the upper mold plate 4, and the upper mold 8 and the lower mold 7 are opened, closed, and clamped via the upper mold plate 4. The reasons why the upper template is required include the following.

That is, (1) it is essential as a structure that can cope with high mold clamping pressure, (2) it is produced in different industries,
Since the interrelationship (standards) between the mold and the injection molding machine is required to be concise and clear, it is convenient to have an upper mold plate with a simple structure as the connection point between the two, (3)
Convenience in operation, i.e., the nozzle of the injection unit can be easily removed from the mold, allowing blank firing for cleaning the inside of the heating cylinder when changing resin, and preventing cooling of the nozzle. It was necessary for.

However, in recent years, injection molding operations have become more diversified, leading to the emergence of various types of operations that do not fit into the background that requires the above-mentioned upper mold plate. One such work style is the intermittent production of small-sized molded products in a wide variety of small quantities.

In order to achieve comprehensive production rationalization, this work style minimizes the amount of parts held in the production system by producing the required number of parts at the required time in each production process. In recent years, it has been viewed as a promising management method.

In such work formats, (1) a large number of small injection units with low mold clamping pressure are generally adopted due to the diversification of molded products, and (2) these injection units and their molds are the same. (3) Each injection unit works as a single function, eliminating the need for operations such as changing the resin, and it is observed that there is a tendency for demands for ease of operation to be relaxed.

Therefore, in the case of intermittent production of a wide variety of small-form products in small quantities, the need for an upper mold plate has receded, but at the same time, the drawbacks and disadvantages of having an upper mold plate have become apparent. There is.

That is, in an injection molding machine that uses an upper mold plate, the nozzle part at the tip of the heating cylinder passes through the upper mold plate and comes into contact with the upper mold, so the heating cylinder needs a nozzle part. However, the resin passage inevitably becomes longer due to the nozzle portion.

Therefore, the residence time of the molten resin in the resin passage becomes longer, and the resin is heated excessively.
It often undergoes deterioration and hardening, and in the above-mentioned high-mix, low-volume intermittent production, the deterioration and hardening resin is mixed into the molded product at the beginning of production, causing unevenness in the molded product and leading to molding defects. .

Furthermore, the presence of the upper mold plate complicates the structure, making the entire device larger and requiring a larger installation space.

Moreover, in order to cause the heating cylinder to penetrate through the upper mold plate and come into contact with the upper mold, a driving device such as an elevating cylinder is required, which makes the above structure even more complicated. It also had the disadvantage of being expensive.

The purpose of the present invention is to solve the above-mentioned problems by attaching the upper mold directly to the tip of the heating cylinder, in view of the problems such as deterioration and hardening of the resin due to the structural limitations of the injection molding machine based on the above-mentioned prior art. It is an object of the present invention to provide an excellent injection molding machine that can eliminate these disadvantages and perform intermittent molding of a wide variety of types and small quantities with extremely high quality.

The structure of the present invention in accordance with the above object is such that during injection molding work, the upper mold, which is directly attached to the tip of the injection unit, is lowered together with the injection unit without having to bring the injection unit into contact with and release from the upper mold through the upper mold plate. The gist of this is that the mold is brought into contact with the mold, the mold is closed and clamped, and the injection work can be performed as is.

Next, an embodiment of the present invention will be described below based on the drawings from FIG. 2 onwards.

In FIG. 2, a rotary table 17 is mounted on a frame 15 and is rotatable about a rotary shaft 16, and a plurality of lower molds 18 are mounted on the rotary table 17.
is installed. On the other hand, a support 19 is erected on the frame 15, and an injection unit 21 is attached to a guide rod 20 provided on the support 19 so as to be able to slide up and down. The axis of the injection unit 21 is aligned with the lower mold 18 located at the injection position A. And injection unit 2
An upper mold 23 is detachably attached to the tip of the first heating cylinder 22. Further, a mold clamping cylinder 24 is connected to the rear end of the injection unit 21.

The upper mold 23 and the heating cylinder 22 of the injection unit 21
The mounting structure with is shown in Figure 3.
An upper mold mounting plate 25 is screwed onto the outer circumference of the tip of the heating cylinder 22, and the upper mold 2 is attached to the upper mold mounting plate 25.
3 is removably attached with a mounting bolt 26.

In addition, 27 is an injection screw, 28 is a hot runner of the upper mold 23, 29 is a heating element, 30 is a mold engraving space,
31 is an ejector pin.

In the above configuration, during injection molding, the injection unit 21 is lowered by the mold clamping cylinder 24, the upper mold 23 at the tip is closed and clamped with respect to the lower mold 18 at the injection position A, and then, It performs injection work. After the injection operation is completed, after a predetermined holding pressure and cooling time have elapsed, the injection unit 21 is raised by the mold clamping cylinder 24, the upper mold 23 is separated from the lower mold 18, and the mold is opened.

In the above embodiments, the lower mold is mounted on a rotary table, but this is not a limitation. Other structures may be used, or a structure in which one lower mold is fixedly aligned with the injection position A may be used.

As described above, according to the present invention, since the upper die is directly attached to the tip of the heating cylinder of the injection unit, there is no need to provide a nozzle part for contacting the upper die at the tip of the heating cylinder. As a result, the resin passage is shortened to that extent, which reduces deterioration and hardening of the resin due to overheating, and has the excellent effect that uniform molded products can be obtained even during intermittent production.

In addition, the elimination of the upper mold plate simplifies the structure and downsizes the entire device, greatly contributing to the miniaturization of low-pressure injection molding machines. It is extremely profitable as an injection molding machine.

In addition, since the upper mold is detachable from the heating cylinder, there is also the effect that the mold can be easily replaced.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an injection molding machine based on the prior art, and FIG. 2 and subsequent figures show embodiments of the present invention, with FIG. 2 being a side view and FIG. 3 being a sectional view of a main part. 17...Rotary table, 18...Lower mold, 21...
...Injection unit, 22...Heating cylinder, 23...Upper mold, 24...Mold clamping cylinder, 25...Upper mold mounting plate, A...Injection position.

Claims (1)

[Claims] 1 a plurality of lower molds 18 disposed at injection position A;
An injection unit 21 is arranged to be movable up and down so as to align with the lower mold at the injection position, an upper mold 23 is detachably attached to the tip of a heating cylinder 22 of the injection unit, and an upper mold 23 is connected to the injection unit. , and a mold clamping cylinder 24 for raising and lowering the injection unit.