JPH01210323A - Injection molding device - Google Patents

Abstract

PURPOSE:To enable the injection pressure of molten raw material to be set low and to unnecessitate the mechanism of an ejector pin by a method in which at least one of a pair of molds is composed of air permeable porous stock, and the pressure in a cavity is regulated by a pressure regulating means. CONSTITUTION:The mold body of movable side is composed of the same porous stock as that of the mold body of stationary side. When a vacuum pump is driven, air is sucked from the molding surface 19 in the mold 16 of stationary side, and air is sucked from the molding surface 30 in the mold 27 of movable side, whereby the pressure in the cavity 37 between the molding surfaces 19, 30 in both molds 16, 27, is reduced. When the state of said reduced pressure in the cavity 37 is confirmed by a vacuum gauge, and said pressure reaches a prescribed pressure, the molten raw material of synthetic resin is injected into the cavity 37 through a nozzle from a raw material-injecting means. Since the pressure inside of the cavity 37 is reduced by a pressure-regulating means, the raw material flows into the cavity 37 smoothly, even if the injection pressure of molten raw material 51 is lowered.

Description

[Detailed description of the invention] (Application field of industry-1-) The present invention can be applied to, for example, an automobile instrument panel. This invention relates to an injection molding device for molding.

(Conventional technology) Conventionally, as shown in FIG. 3, a pair of molds 1 are used.

An injection molding apparatus is known that molds a synthetic resin product 1 by injecting it into a cavity 3 formed by combining two parts.

(Problem to be solved by the invention) In such conventional injection molding equipment, AB with high viscosity
In the case of S resin, etc., the injection pressure must be increased, and along with this, the durability of the image forming mold 1.2.

There was a problem in that it was necessary to increase the compression strength and complicate the formation of the sealing part, and there was a risk that the protruding parts in the image forming molds 1 and 2 would break due to the injection pressure. .

In addition, in conventional injection molding equipment, one mold 2
Another problem is that the structure is complicated because a plurality of ejector turbine mechanisms 6 each consisting of an inner bin 4 and an outer turbine 5 for rigidizing the molded product are provided.

The present invention was made in view of the above circumstances, and it is possible to set the injection pressure of the molten raw material low, and there is no need to increase the pressure resistance of the mold or complicate the structure of the seal part. Moreover, it is an object of the present invention to provide an injection molding apparatus that does not require an ejector turbine mechanism.

(Means for Solving the Problems) In order to achieve the above object, the injection molding apparatus of the present invention comprises at least one of a pair of molds made of a porous moon having air permeability, and the one mold The inside of the cavity is connected to a pressure adjustment means, and the pressure inside the cavity can be adjusted by the pressure adjustment stages ff1 to f.

(Function) In the injection molding process, the pressure inside the cavity is reduced by the pressure regulating means, so even if the injection pressure is low, the molten raw material smoothly and evenly infiltrates every corner of the cavity. Furthermore, in the mold release step, the pressure regulating means supplies air to the cavity side and pressurizes it, so that the product in the cavity is reliably released from the mold.

(Example) Hereinafter, an example of the present invention will be described based on FIGS. 1 and 2. FIG. 1 is an overall configuration diagram of an injection molding apparatus according to the present invention. In the figure, reference numeral 10 denotes an injection molding apparatus, which has a mold unit 11 on a fixed side and a mold unit 12 on a movable side.

The mold unit 11 on the fixed side is formed by installing a mold (female mold) 16 on one side of a bottom plate 13 via a stripper plate runner stripper plate 15. The mold 16 includes a mold main body 17 and a mold sub-body 1.
8 and are mutually polymerized. The mold main body 17 is formed by fitting and fixing a mold main body 20 having a concave mold surface 19 on the negative side into a frame 21 . The mold main body 20 is made of an air-permeable porous material such as sintered ceramic having a large number of open cells. That is, the mold main body 20 is made by kneading mullite, cast iron, and metal fibers, hardening them with a binder, and then sintering them at 1000° C. In this way, the mold main body 20 is constructed by sintering ceramics. from,
The surface of the mold surface 19 is inevitably grained. Therefore, when molding a product whose surface is finished in a matte finish, there is no need to apply texture to the surface of the special mold surface 19. The mold sub-body 18 is formed by fitting and fixing a plate 22 made of an air-permeable casting having a large number of open cells into a frame 23.

Furthermore, the mold unit 12 on the movable side has a mold ( t
(I type) 27 is taken (= J is made. The mold 27 is
It is formed by overlapping a mold body 28 and a mold sub-body 29 with each other. The mold main body 28 is formed by fitting and fixing a mold main body 31 having a mold surface 30 convex on the negative side into a frame 32 . The mold main body 31 is composed of a porous tube similar to the mold main body 20 on the fixed side. The mold sub-body 29 is formed by fitting and fixing a plate 33 made of air-permeable casting similar to the mold sub-body 18 on the stationary side into the frame body 34.

The tip of a nozzle 35 for supplying raw material is connected to the raw material supply port of the bottom plate 13 of the mold unit 11 on the fixed side, and the base end of the nozzle 35 is connected to a raw material injection means (not shown).
It is connected to.

In addition, the bottom plate 2 of the mold unit 12 on the movable side
4 is connected to the tip of the ram 36.

Then, the movable mold unit 12 is moved to the fixed mold unit 11 side by the ram 36, and both molds 1
6.27, a cavity 37 corresponding to the product to be molded is formed between both mold surfaces 19 and 30, and by filling the cavity 37 with raw materials, the product can be molded. It has become.

Is there pressure inside both molds 16 and 27? It is connected to the A117 means 38. This pressure adjustment means 38 is a vacuum pump 39
The suction side of the vacuum pump 39 is connected to one connection port 42 of a decompression tank 41 via a first pipe line 40, and the other connection port 43 of this decompression tank 41 is connected to a first connection port 42 of a decompression tank 41. It is connected to an industrial pressurized air supply source (not shown) via a two-pipe line 44. In this second conduit 44, first, second, and third on-off valves 451, 452, and 453 are arranged in series at intervals from each other. A first branch line 46 located between the second and third on-off valves 452 and 453 and branched from the second line 44 is connected to the inside of the plate 22 of the mold sub-body 18 on the stationary side. There is. Also, the first
A fourth on-off valve 454 is provided in the branch pipe line 46 .

A second branch line 47 located on the second line 44 side of the fourth on-off valve 454 and branched from the first branch line 46 communicates with the inside of the brake I/33 of the mold subbody 29 on the movable side. It is connected. A fifth on-off valve 455 is provided in the first branch pipe line 46. A fifth on-off valve 455 of the second branch pipe line 47 is provided.
The side closer to the plate 33 and the first and second on-off valves 451 and 452 of the second conduit 44 are connected through a communication conduit 48 . A vacuum Ml' 49 and a pressure table 150 are interposed between the first branch pipe line 46 and the communication pipe line 48.

Next, the operation of the injection molding apparatus 10 of the present invention will be explained with reference to FIG.

The movable mold unit 12 is moved to the fixed mold unit 1 side by the ram 36, and the image mold 16.2 is moved to the fixed mold unit 1 side.
7 as shown in FIG. 2 (1) (mold closing process). Next, the first. The second and fourth on-off valves 4.5+, 4.52 and 454 are opened, and the third and fifth on-off valves 453
and 455 are closed and the vacuum pump 39 is driven,
First conduit 40. The pressure inside the decompression tank 4 is reduced. Then, air is sucked from the mold surface 19 of the mold 16 on the fixed side through the second pipe line 44 and the first branch pipe line 46, and the second pipe line 44. By suctioning air from the mold surface 30 of the movable mold 27 through the communication pipe 48 and the second branch pipe 47, the inside of the cavity 37 between the mold surfaces 19 and 30 of the image mold 16 and 27 is drawn. or depressurized.

Then, the reduced pressure state in the cavity 37 is confirmed by the vacuum pump 49, and when the predetermined pressure is reached, the pressure is injected into the cavity 37 from the original injection means through the nozzle 35 as shown in Fig. 2 (1).
]) As shown in 1.
．． 51 is injected (injection process).

During the injection process, since the pressure inside the cavity 37 is reduced by the pressure regulating means 38, the molten raw material 5
Even if the injection pressure of No. 1 is lowered, the raw material flows smoothly into the cavity 37.

In this way, when the injection process is completed, the on-off valves 451 to 155 are left as they are and the cavity 3 is closed.
While maintaining the inside of 7 in a reduced pressure state, press the drawing mold 16.27.
is cooled by a known cooling means (not shown) as shown in FIG. 2 (Ifl) (cooling step).

In the cooling step, the molten piece Jul inside the cavity 37
51 is cooled and solidified to become a product 52. During this cooling stage, the air within the cavity 37 is sucked by the pressure regulating means 38, so that the cooling effect of the product 52 within the cavity 37 is high.

In this way, when the first stage of cooling is completed, the first stage.
The fourth and fifth opening/closing valves 4.51, 454, and 455 are left as they are, and the second opening/closing valve 452 is closed, and the third opening/closing valve r453 is opened.
6, the molding die 27 on the movable side is separated from the molding die 16 on the fixed side as shown in FIG. 2 (IV) (mold opening approximately 1).

In this mold opening process, the mold surface 3 of the movable mold 27 is
Since the air is sucked through the air, the product 52 is attracted to the mold surface 30, and the mold surface 19 of the fixed mold 6 is supplied with industrial pressurized air or the second TF1-path 44 and the first branch pipe. 46
1jIIl molding of the product 52 from the mold surface 19 is carried out smoothly. Therefore,
There is no risk that the product 52 will be damaged during the mold opening process.

When the mold opening process is completed in this way, the second and third on-off valves 452 and 453 are left as they are, the first and fourth on-off valves 151 and 454 are closed, and the fifth on-off valve is closed. Open p455.

Then, industrial pressurized air is force-fed to the mold surface 30 of the mold 27 on the movable side via the second pipe line 4/I, the first branch pipe line 46, and the second branch pipe line 47. Therefore, the product 52 on the mold surface 301 is subjected to extrusion pressure by this forced air, and is removed from the mold surface 30 as shown in FIG. 2(V) (product removal step).

In this way, when the product removal process is completed, the second
Moving on to the mold closing process shown in Figure (1), the drawing mold 16.27
can be matched.

Table (1) shows comparative examples of molding using the injection molding apparatus σ of the present invention with the inside of the cavity 37 at atmospheric pressure and molding under reduced pressure.

Table (1) ◎: Very good ○, good △: Normal In the table (1), low pressure means that the inside of the cavity 37 is in a vacuum state (70
This is the case when the weight is 0 mm and 11 g or more.

Also, grain reversal means that both molds 16.
The grains on the surfaces of mold surfaces 19 and 30 of No. 27 are transferred, and the surface of the product 52 becomes satin-like (matte).

As is clear from this table (1), grain reversal, matte degree,
In terms of sink marks, warpage, and low molding pressure, conditions at low pressure are better than at atmospheric pressure, and overall,
It is better at low pressure.

In this embodiment, the main body 20° 31 of the image forming mold is made of a porous material having air permeability, but the present invention is not limited to this. 1. Even if only the main body 41 side is made of a porous material, it is possible to implement the present invention.Also, although the porous material is also made of sintered ceramics, the porous material is not limited to this. In the case of a non-metallic type, spherical epoxy resin 2 may be gypsum, cement, etc. In the case of spherical epoxy resin, the spherical epoxy resin is laminated and sanded back to form the image mold main body 20.31. Further, in the case of plaster, cement, etc., the plaster, cement, etc. are hardened with a binder and dried, and the image forming mold main body 20.31 is formed.

In addition, the image forming mold is mainly made of metal-based porous material 20.3
1 can be formed by electroforming using copper or nickel as raw material, casting using FC2 zinc metal as raw material, or thermal spraying using aluminum powder, zinc alloy, or nickel as raw material.

In the case of electroforming, the property that the material becomes porous when the timing of electroforming is changed is utilized. Also,
Casting involves intentionally creating countless fine holes (holes) when casting FC and the like.

The powder is made by kneading aluminum powder with a binder and layering it with a sandbag. Furthermore, thermal spraying is
It uses a high-voltage electrode gun to spark and blow zinc metal, etc.

(Effects of the Invention) As described in detail above, the injection molding apparatus of the present invention includes at least one of the pair of molds made of a porous material having air permeability, and the inside of the one mold is controlled by pressure regulating means. The pressure adjustment means is connected to the cavity so that the pressure inside the cavity can be adjusted.

Therefore, in the injection process, by reducing the pressure inside the cavity by the pressure 'A adjustment means, the molten raw material can smoothly flow into every corner of the cavity without increasing the injection pressure. Since the injection pressure can be lowered in this way, there is no need to increase the pressure resistance of both molds or complicate the structure of the seal part, and there is no need to break small protrusions due to injection pressure. It is also possible to mold products.

In addition, in the mold opening process and the product removal process, by supplying pressurized air to the mold surface using the pressure adjustment means and pressurizing it, extrusion pressure can be applied to the product in the cavity, so that the first mold of the product can be smoothly and You can definitely do it. Therefore, the eject turbine mechanism that was conventionally provided becomes unnecessary, and the configuration becomes simple.

Moreover, the mold surface of the mold made of porous layers is
Since the base of the porous material itself is exposed as it is and the grain is formed, when molding a product with a satin finish, there is no need to apply special graining to the surface of the mold.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of an injection molding apparatus showing an embodiment of the present invention, FIG. 2 is an explanatory diagram of the molding process of the same apparatus, and FIG. 3 is a diagram of the main part configuration of a conventional injection molding apparatus. 10... Injection molding device, 16.27 Molding mold, 19°30... Mold surface, 37... Cavity, 38... Pressure adjustment means.

Claims (1)

[Claims] 1. In an injection molding device that molds a product by injecting a raw material into a cavity formed between a pair of mold surfaces by fitting a pair of molds together, at least one of the pair of molds is made breathable. The injection molding is made of a porous material having a porous material, and the inside of the one mold is connected to a pressure adjustment means, so that the pressure inside the cavity can be adjusted by the pressure adjustment means. Device.