JP3224840B2 - Method and apparatus for manufacturing hollow resin molded product - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a resin product having a hollow portion inside the product.

[0002]

2. Description of the Related Art Conventionally, in the case of a resin product such as a plastic material, a hollow portion is sometimes formed inside the product in order to reduce the weight and the like. An apparatus as disclosed in Japanese Patent Application Laid-Open No. 64-14012 is known. This apparatus is provided with a gas injection nozzle for injecting a gas into the molten resin filled in the mold cavity, and this nozzle can be freely moved toward and out of the cavity. In addition, since the molten resin injected into the cavity rapidly solidifies on the filling end side, it is advantageous to set the gas injection portion to the filling end side to uniformly inject gas into the resin. Devices are also known in which the injection nozzle is arranged on the filling end of the cavity.

[0003]

However, in the conventional case,
For example, as shown in FIG.
After filling the molten resin into the cavity 54 of the molds 52 and 53 from 1, the gas injection device 55 is inserted into the resin of the cavity 54.
Gas is injected from the cavity 5
There is a problem that, as shown by the arrow, it does not stay in the molten resin inside 4 but also penetrates to the upstream portion on the resin filling side and enters further upstream of the injection nozzle 51. For this reason, the molten resin mixed with the gas at the next injection is used as it is in the cavity 5.
4, the quality of the product is deteriorated. Since the molten state is particularly high on the upstream side of the molten resin, such a problem is likely to occur even when the gas is injected from the filling end side. It is also conceivable to lower the gas pressure in order to prevent such problems, but if the gas pressure is lowered, sink marks and the like are likely to occur, and the molding quality cannot be improved.

[0004]

In order to solve such a problem, the present invention provides a method for injecting a molten resin into a cavity.
When manufacturing a hollow resin molded product in which gas is injected into the resin from the filling end side, the non-product part downstream of the resin injection part is sealed with gas sealing means, and the communication between the resin injection part and the cavity is cut off In this state, gas was injected from the gas injection means, and the gas injection means and the gas sealing means were connected by an interlocking mechanism. Further, the gas sealing means is provided with an engaging member which engages with the non-product portion on the resin filling upstream side.

[0005]

The gas does not proceed to the injection molding machine side by the gas sealing means, and there is no problem that the gas is mixed in the next resin injection. At this time, since the gas pressure can be freely adjusted, the molding quality can be improved. If the gas injection means and the gas sealing means are connected by an interlocking mechanism, the apparatus can be simplified.
In addition, the engaging member is moved forward and backward as gas sealing means, and the engaging member is moved forward to perform gas sealing, and when the engaging member is moved backward, the engaging member is filled with non-product on the upstream side. If the non-product part is engaged with the part, the non-product part on the upstream side is withdrawn, and the subsequent cutting operation of the non-product part becomes easy.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method and an apparatus for manufacturing a hollow resin molded product of the present invention will be described with reference to the accompanying drawings. FIG.
2 is an overall view of the manufacturing apparatus, FIG. 2 is an enlarged view of an essential part of FIG. 1 showing an example of gas sealing means, and FIG. 3 is an enlarged view of an engagement member.

As shown in FIG. 1, a manufacturing apparatus for manufacturing a hollow resin product such as a plastic comprises an injection nozzle 1 on an injection molding machine side as a resin injection section, and a pair of dies 2 and 3.
And a gas injector 5 serving as gas injection means, and the molten resin injected from the injection nozzle 1 is filled into the cavity 4 via the runner part 6 and the non-product part 7 of the mold 2. Then, pressurized gas is injected from the gas injector 5 toward the inside of the resin to hollow the inside.

That is, the surface layer of the molten resin filled in the cavity 4 becomes semi-solid, and while the inside is not solidified, the gas injection member 8 having a sharp tip is projected into the cavity 4 so that After making a hole in the portion, the gas injection member 8 is retracted to open the gas supply passage 10, and the pressurized gas is introduced into the resin.

To this end, the gas injector 5 provided in the mold 3 is provided with a cylinder portion 11 and a piston portion 12 for moving the gas injecting member 8 forward and backward. The piston portion 12 is driven by utilizing this.

The gas injector 5 is provided in the cavity 4 far from the resin filling side, that is, on the filling end side.

By the way, in the manufacturing apparatus of the present invention, a gas sealing means as a gas sealing means is provided so that the gas in the cavity 4 does not permeate toward the upstream side of the resin filling via the non-product part 7, the runner part 6 and the like. The stop mechanism 13 is provided, and details thereof will be described with reference to FIG.

As shown in FIG. 2, the non-product part 7 is composed of a sprue 7a which is a tapered vertical passage and a horizontal runner 7b which communicates with the cavity 4 through a gate 9. The connection between the sprue 7a and the horizontal runner 7b can be cut off.

That is, the gas sealing mechanism 13 is provided on the mold 3 where the resin flow path is not formed, and the sprue 7a
Engaging member 14 which is located on the extension of
And a piston portion 1 for driving the engagement member 14 to move up and down.
5 and a cylinder 16 for guiding the sliding of the piston 15. And the piston part 15 and the engaging member 1
4 are connected via a coupling 17.

The upper end of the engaging member 14 is tapered at the tip and can be inserted into the sprue 7a. When the upper end of the engaging member 14 rises by a certain amount, it blocks the outlet of the sprue 7a and cuts off the communication between the sprue 7a and the horizontal runner 7b. The engaging notch 14a as shown in FIG. 3 is provided at the tip of the engaging member 14 to be inserted into the sprue 7a when it rises.

The piston portion 15 of the gas sealing mechanism 13 is driven by a fluid driving pressure such as a hydraulic pressure or an air pressure, and is controlled by the same control mechanism as the gas injector 5, for example.

On the other hand, the gas injector 5 and the gas sealing mechanism 1
3, an interlocking mechanism 18 is provided. That is, the interlocking mechanism 18 is, for example,
One of the cylinder chambers is connected by a communication line, and by lowering one of the piston sections, the other piston section is automatically raised.

Next, a manufacturing method using the manufacturing apparatus configured as described above will be described.

With the dies 2 and 3 clamped, a predetermined amount of molten resin is filled into the cavity 4 from the injection nozzle 1 of the injection molding machine. At this time, the gas injection member 8 of the gas injection device 5 and the engagement member 14 of the gas sealing mechanism 13 shown in FIG.

When a predetermined amount of molten resin is filled in the cavity 4 and the surface layer is semi-solidified, gas is injected. That is, for example, a fluid pressure is introduced into the cylinder portion 15 of the gas sealing mechanism 13 and the piston portion 15 in the state of FIG.
2 is slightly pushed up, and a hole is made in the resin surface layer at the pointed tip of the gas injection member 8.

When drilling is completed, fluid pressure is introduced into the cylinder 11 on the gas injector 5 side, and the piston 12
Is greatly pushed down to open the gas supply passage 10, and at the same time, the piston 15 of the gas sealing mechanism 13 on the opposite side is pushed up via the communication mechanism 8, and the sprue 7a of the non-product part 7 is And the communication part of the horizontal runner 7b is shut off.

In this state, the pressurized gas permeates the unsolidified portion inside the resin, and presses the unsolidified portion against the surrounding cavity wall or the like to hollow the inside of the thick portion. .

At this time, even if the gas enters the horizontal runner 7b, the gas does not permeate any further upstream by the engaging member and is reliably prevented.

In this way, the solidification is carried out by cooling while maintaining the gas pressure, and the mold is opened when the molding is completed. However, before the engaging member 14 of the gas sealing mechanism 13 is retracted, the non-product portion 7 is opened.
Out of the sprue 7a can be automatically removed.

That is, normally, the non-product part 7 is taken out together with the product part in the cavity 4, but in the case of the present invention, the resin of the sprue 7a is separated from the horizontal runner 7b. This is because the solidified portion engages with the engagement notch portion 14a of the engagement member 14 and is pulled out together by the retreat of the engagement member 14.

Therefore, even if the horizontal runner 7b remains to be cut off thereafter, the size and shape of the cut-out portion are simplified, and the work becomes easier. Further, the gas injected into the inside is evacuated by any means after completion of molding.

[0026]

As described above, the molding method of the present invention prevents the gas for hollow molding from flowing into the outside of the resin filling upstream from the cavity. There is no defect such as filling and causing molding failure. Also, there is no problem that the gas pressure has to be lowered to avoid gas inflow as in the past, and the gas pressure can be freely changed according to the shape, hollow shape, size, etc. of the molded product, so that the molding quality is improved. I can do it. At this time, the apparatus can be simplified if the gas injection means and the gas sealing means are connected by an interlocking mechanism. Further, by automatically separating the non-product portion on the upstream side of the resin filling by the engagement member, there is an effect that the subsequent cutting operation is facilitated.

[Brief description of the drawings]

FIG. 1 is an overall view of a manufacturing apparatus.

FIG. 2 is an enlarged view of a main part showing an example of gas sealing means.

FIG. 3 is an enlarged view of an engagement member.

FIG. 4 is an explanatory view of a conventional manufacturing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Injection nozzle 4 Cavity 5 Gas injector 7 Non-product part 13 Gas sealing mechanism 14 Engaging member 18 Interlocking mechanism

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Teruo Ichikawa 1-10-1 Shinsayama, Sayama City, Saitama Prefecture Inside Honda Engineering Co., Ltd. (72) Inventor Riya Saito 1-10-1 Shinzayama, Sayama City, Saitama Prefecture (56) References JP-A-5-124064 (JP, A) JP-A-4-45909 (JP, A) JP-A-5-154862 (JP, A) JP-A 64-14012 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 45/00-45/84

Claims (3)

(57) [Claims] 1. A method of manufacturing a hollow resin molded product, wherein a molten resin is injected into a mold cavity from a resin injection portion, and then a gas is injected from a filling end side to form a hollow portion inside the molded product. A method of manufacturing a hollow resin molded product, comprising: sealing a non-product part downstream of a resin injection part with a gas sealing means at the time of injecting the gas to cut off communication between a cavity and the resin injection part. 2. An apparatus for manufacturing a hollow resin molded article, comprising: an injection molding machine for injecting a molten resin from a resin injection section into a mold cavity; and a gas injection means for injecting a gas into the molten resin from a filling end side. In the non-product part downstream of the resin injection part, gas sealing means for interrupting communication between the resin injection part and the cavity is provided, and an interlocking mechanism is provided between the gas sealing means and the gas injection means. An apparatus for producing a hollow resin molded product. 3. The apparatus for manufacturing a hollow resin molded product according to claim 2, wherein said gas sealing means includes an engaging member which engages with a non-product portion on an upstream side of resin filling.