JPS63216720A - Extrusion and pressing-in molding method for synthetic resin - Google Patents

Abstract

PURPOSE:To obtain a complete molded product economically, by a method wherein a large quantity of a predetermined quantity of resin is extruded to a molding mold in a short period of time by enlarging a bore of an extrusion port and accumulated residual resin is pressed into a pressing-in resin chamber. CONSTITUTION:Resin A is kept stored within an extrusion chamber 3 whose extrusion port 5 is closed, when a reed valve 2 is opened, a thermally-plasticized resin and another resin are supplied newly within an extrusion chamber 3 respectively through an extrusion machine 1 and auxiliary chamber 15, through which a plunger 10 is moved backward. Primary extrusion of the stored resin A controlled to a low temperature into a space 9 within a mold is performed in succession by a predetermined quantity through an extrusion path 7 by moving the plunger 10 forward and opening the extrusion port 5 and extrusion path 7 by moving a mandrel 11 backward. Subsequently, the mandrel 11 is moved forward, high-pressure pressing is applied to a residual dwell resin B, thereby being pressed into the space 9 within the mold of a molding mold. An industrial molded product of a reinforced nylon resin whose cooling period of time is sufficient can be obtained like this.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention produces stable molded products with little thermal deterioration and residual stress by extruding and press-fitting thermoplasticized resin into a mold at an appropriate temperature using an extruder. The present invention relates to an extrusion press-fit molding method for synthetic resin obtained.

<Conventional technology> Conventionally, as a method of in-mold molding using thermoplastic resin,
There is a method in which an injection chamber is filled with thermoplasticized resin at an appropriate temperature, and the resin is injected into a mold at high pressure through a small-diameter injection port. When high-pressure injection is performed through such a small injection port to generate frictional heat and the resin temperature rises to improve mold circulation and obtain a molded product, the rise in resin temperature during injection causes thermal deterioration and residual stress. As a result, only molded products with deteriorated physical properties were obtained. Further, in the case of reinforced resin containing glass fiber or the like, there is a problem in that the fibers are crushed when passing through a small injection port and the desired physical properties cannot be achieved.

As a way to prevent the generation of frictional heat as much as possible, raising the resin temperature above the appropriate temperature to improve fluidity will lead to the aforementioned thermal deterioration from the beginning, and if this is rapidly cooled, stress will remain. . If the resin temperature was adjusted to an appropriate temperature and the injection time was increased, the mold movement into the mold would be slow and this would increase the incidence of defective products.

Furthermore, if the above-mentioned molding conditions were adopted, and the injection speed was slowed and the cooling period was extended, the time required for molding would increase, resulting in inefficiency, and it was still difficult to obtain a perfect molded product experimentally. .

<Problems to be Solved by the Invention> Recently, so-called engineered plastics with excellent physical properties have been developed as resin raw materials, and opportunities for their application are increasing. However, the above method of injection molding this resin impairs the excellent properties of the resin.

Therefore, there is an urgent need to develop a new molding method that does not impede the properties of such resins. An object of the present invention is to provide a synthetic resin extrusion press-fit molding method that can meet the above requirements.

Means for Solving the Problems> The present invention provides a method for filling an extrusion chamber with resin thermoplasticized by an extruder and extrusion molding, in which the extrusion path of the mold communicating with the extrusion port of the extrusion chamber has a diameter of A press-fitting resin chamber is configured with
The resin remaining in the press-fitting resin chamber composed of an extrusion port and an extrusion path was secondarily press-fitted into the mold. Further, the residual resin can be press-fitted while returning the surplus to the extrusion chamber.

As mentioned above, a press-fit resin chamber is configured by increasing the diameter of the extrusion port and extrusion path, and through this a large amount of resin is extruded into the mold in a short time, and the press-fit resin chamber is configured by the extrusion port and extrusion path. A major feature of the present invention is that the accumulated residual resin is press-fitted into the mold by a pressing means.

When molding a large molded product (1.5k (J)), the degree to which the extrusion port and extrusion path are enlarged is 0.
The diameter of the injection path, which was about 75 CIIl, is expanded to, for example, four times that diameter, about 3 cm.

In this case, extrusion is performed at a low speed of 1:16 between the present invention and the conventional method. Furthermore, the ratio of diameters that generate frictional heat with velocity energy proportional to the square of velocity is 1:64.

<Effects of the Invention> The present invention can suppress the speed of the resin extruded from the extrusion port and extrusion path into the mold in the first stage to a low speed of 0.5 m/SeC, which is about 1/16 of the conventional method. is possible,
In addition to reducing the rise in resin temperature due to friction, even if glass fiber or the like is mixed, it is possible to reduce the possibility of it being broken into small pieces. In addition, since a predetermined amount of resin kept at a low temperature is subtracted from the volume of the extrusion port and the extrusion path through the large-diameter extrusion path into the mold by the extrusion means, the resin inside the mold is A large amount of resin can be extruded in a short time at low pressure.

Even resins with high melt viscosity and low fluidity at appropriate temperatures can be extruded in large quantities in a short period of time, allowing rapid mold turning. The residual resin stored in the press-fitting resin chamber constituted by the extrusion port and extrusion path is secondarily press-fitted into the mold by high-pressure suppressing means. As a result, the inside of the mold is filled, and a perfect molded product is obtained without defects due to mid-stage assimilation. The low-temperature storage resin in the extrusion chamber is more efficient than the extrusion port or extrusion path because even if a large amount of resin is extruded into the mold in a shorter time, the resin temperature does not rise much, so less cooling is required, and the molding time can be shortened. be.

The method of the present invention is not only effective for extrusion press-fit molding of extrusion grade, which is a high-density resin with high viscosity and good physical properties, but also allows the mold to be used as a bottomed parison for blow molding. By changing to a mold, it is also effective when molding a large, thick-walled parison with a bottom that is ideal for blow molding.

In addition, the present invention provides a predetermined amount of resin in the extrusion chamber at an appropriate temperature from the large-diameter extrusion port and extrusion path into the mold (the port after subtracting the residual resin for the volume of the press-fit resin chamber made up of the extrusion port and the extrusion path). Errors may occur during primary extrusion. If this amount is small, even if the residual resin mentioned above is press-fitted into the mold using the secondary suppression means, it will not be able to fill it, resulting in a defective product. Molding may also be performed by providing relief grooves or the like at the joints of the molds to allow excess resin to escape. In order to make effective use of this resin, the excess residual resin is returned to the extrusion chamber and is press-fitted into the mold during secondary compression, which prevents excessive pressing force from being applied and A complete molded product with no protrusions is 1q.

<Example> First, I will give an overview of the molding machine used.

An extrusion chamber 3 communicating with the outlet side of the extruder 1 via an on-off valve 2 is attached to a pressure plate 4 of a mold clamping device.

This extrusion chamber 3 has a diameter of 120φ except for the tip, which serves as an extrusion port 5 with an inner diameter of 30φ and a molding concave mold 6.
It communicates with an extrusion path 7 formed in the. The extrusion path 7 is continuous with the extrusion port 5, has a diameter of 30φ, and communicates with the mold space 9 formed by the molding concave mold 6 and the molding convex mold 8. The plunger 10, which can be advanced and retracted by sliding a portion with an inner diameter of 120φ inside the extrusion chamber 3 described above, is actuated by the extrusion means 16, and can be advanced and retracted by penetrating the central portion of the plunger 10 by the pressing means 17. Mandrel 1
1 is installed. Plunger 10 and mandrel 1
As shown in FIGS. 1, 2, 3, and 4, the extrusion port 5 and the extrusion path 7 are not blocked in the retracted position, but are completely blocked in the forward position. It gets blocked by. For this reason, the tip portion of the mandrel 11 is shaped to tightly fit into a press-fit resin chamber composed of an extrusion port 5 and an extrusion path 7 having an inner diameter of 30φ. Figures 5 and 6
In the figure, a small hole is formed from the tip of a mandrel 11 fitted into an extrusion port 5 and an extrusion path 7 to form a return path 12 for the resin, and the end thereof forms a path 13 for the resin.

Since 1 mA of resin from the extruder 11 is continuously extruded even when the on-off valve 2 is closed, an auxiliary plunger 14 that is pushed up by the resin pressure at that time is set so that the auxiliary plunger 14 is temporarily stored in the auxiliary chamber 15. It has become.

An example of forming an industrial article with a wall thickness of 3 mm and a weight of 1.5 kg using a glass fiber-reinforced nylon resin using the above-described molding machine will be described below.

Initially, 3 kg of resin maintained at a low temperature of 225° C. is stored in the extrusion chamber 3 with the extrusion port 5 closed as shown in FIG.
1.25 kg of resin thermoplasticized at 230°C from
When the liquid had moved back by 100 mm, a limit switch (not shown) for quantitative filling was activated to close the on-off valve 2 again. This took 50 seconds. As a result, the resin A in the extrusion chamber 3 becomes 4.5 kc+.

Subsequently, as shown in FIG. 1, the mandrel 11 is retreated to open the extrusion port 5 and the extrusion path 7, and the plunger 10 is advanced to extrude the extrusion path 7 of 30φ at a speed of 0.5 m/SeC.
The first extrusion is carried out into the mold interior space 9 in 3.6 seconds using a predetermined amount of 1.4 kg of the stored resin A, which was previously filled and adjusted to a low temperature. This predetermined amount is
Residual resin B in the volume of the press-fit resin chamber made up of
This is the amount obtained by subtracting 0.1 kg of i. Plunger 1
When the advance of 0 becomes equal to the filling amount of 1.5 kg mentioned above, the plunger 10 stops advancing by actuation of a limit switch (not shown). Subsequently, the mandrel 11 is advanced as shown in FIGS. 3 and 4, and a high pressure is applied to suppress the amount of residual resin B of 0.1 ka stagnant in the press-fit resin chamber in the extrusion port 5 and the extrusion path 7. A secondary press fit is performed in the mold space 9 of the mold to reduce the amount of resin in the mold to 1. Make it shg. The time required for this was 10 seconds including the first extrusion and the second press-fitting. The resin remaining in the extrusion port 5 and the extrusion path 7 is pressed with high pressure and press-fitted into the mold space 9 of the mold, and the excess resin is extruded through the resin return path 12 formed on the mandrel 11 and the resin path 13. It was returned to chamber 3. In this way, an industrial molded product of 1.5k (J
could be obtained in 60 seconds.

[Brief explanation of the drawing]

The figures are provided to facilitate understanding of the present invention, and FIG. 1 is a cross-sectional view showing the state during primary extrusion into the mold;
Fig. 2 is a cross-sectional view showing the state of being press-fitted into the mold by secondary compression, and Figs. This is a cross-sectional view showing a press-fit state with secondary compression. A...Reservoir resin, B...Residual resin, 1...Extruder, 2...Opening/closing valve, 3...Extrusion chamber, 5...
Extrusion port, 7... Extrusion path, 10... Plunger, 1
1... Mandrel, 16... Extrusion means, 17...
Pressing means. Figure 1 Figure 2 Gin ~ η

Claims (1)

[Claims] 1. In a method of filling an extrusion chamber with resin thermoplasticized by an extruder and extrusion molding, the extrusion path of the mold communicating with the extrusion port of the extrusion chamber has a large diameter. A press-fitting resin chamber is constructed, and a predetermined amount of resin in the extrusion chamber is first extruded into a mold, and then the resin remaining in the press-fitting resin chamber, which is composed of the extrusion port and extrusion path, is first extruded into the mold. A synthetic resin extrusion press-fitting method characterized by secondary press-fitting. 2. The method of extruding and press-fitting a synthetic resin according to claim 1, wherein the residual resin is press-fitted while returning the excess resin to the extrusion chamber.