JPS59155017A - Manufacture of molded body in mold - Google Patents

Abstract

PURPOSE:To obtain a molded body with high dimensional accuracy that is suitable to be used as a core material for a bumper and has a curved surface or slanted surface, by carrying out foam molding in such a way that the tip of an ejection pin or a feeder provided at an arcuate section or slanted section of a mold surface is positioned inside a mold. CONSTITUTION:For example, a core mold 5 is fitted to a cavity mold 4 by a piston rod 10, the forward end surface 7 of each of ejection pins 6 is positioned beyond an arcuate section 22 into the mold, then prefoamed particles 13 are fed from a raw material introducing port 16, and are passed through a raw material path 17 and a filling port 14 to be introduced into a molding chamber 11, and then the filling port 14 is closed by the piston 20. At this time, the forward end surface 21 of the piston 20 is positioned away from the arcuate section 22 and inside the mold. Then the prefoamed particles 13 are heated by a suitable heating medium so that they are allowed to foam and thus a core material 12 for a bumper can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an in-mold molded body having two curved or inclined surfaces. An example of an in-mold molded body having a curved or inclined surface is a core material for an automobile bumper.

Conventionally, metal plates have been used as bumpers for automobiles, but with the recent demand for lighter automobiles in order to save energy, metal plates have been used on the surface of the bumper core material 12, as shown in Figure 5. Skin material 23. A bumper 25 with a mounting plate 24 attached is now used and is made of polyurethane foam.

Various synthetic resin foams such as polystyrene foam and polyethylene foam have come to be used as core materials for bumpers.

However, when the bumper core material 12 is molded in a mold, the tip of an operating rod B such as an eject pin or a feeder piston is positioned as shown in FIG. 1, and the pre-expanded particles C are heated and foamed. However, a gap as shown in the figure is created between the tip of the first actuating rod B and the second circular arc part or inclined part, and this gap is also filled with the particles C, so that the resulting bumper A protrusion is formed on the core material 12, and the protrusion forms a surface material 23 on the surface of the core material 12. This becomes an obstacle when attaching the mounting plate 24, etc., and leaves some room for improvement as a core material for bumpers.

An object of the present invention is to provide a method for manufacturing a molded body 2 having a curved or inclined surface, such as a core material for a bumper, which is a further improvement over the above-mentioned prior art.

That is, the present invention has two mold surfaces, an arcuate portion or an inclined portion formed in all or a part of at least one of the mold surfaces, and at least one of which is provided in the circular arc portion or inclined portion of the Venus surface. a mold comprising an eject pin and a feeder, and filling the mold with pre-expanded thermoplastic resin particles;
In a method for manufacturing an in-mold molded product in which a molded product according to the mold is obtained by heating 2 and foaming, the tip of an eject pin and/or the tip of a piston of a feeder provided at a circular arc portion or an inclined portion of the mold surface is connected to the circular arc portion. Alternatively, the gist of the present invention is a method for producing an in-mold molded body, which is characterized in that the molded body is molded by being positioned inside the mold from the inclined part.

Examples of the material for the pre-expanded thermoplastic resin particles used in the present invention include polypropylene, ethylene-propylene random copolymer, and polyethylene.

Examples include polystyrene, which may or may not be crosslinked, but non-crosslinked polypropylene resins are particularly preferred.

Hereinafter, two embodiments of the present invention will be described with reference to the drawings, taking as an example the manufacture of a core material for one use. FIG. 2 shows an example of the mold 1 used in the manufacturing method of the present invention. This metal sound consists of a box frame 2 as an outer frame and an inner mold 3 located inside this box frame 2. Further, the mold 1 is composed of a cavity mold 4 and a core mold 5. The core mold 5 is connected to a piston rod 10 of a hydraulic cylinder (not shown) and is configured to move forward and backward, and when it moves forward, the cavity mold 4 and the core mold 5 come into contact with each other and close the mold. 2-car type 4.5
A molding chamber 11 as a cavity is formed in between, and this molding chamber 11 allows the core material for the bumper to be formed. 2 is formed. Figure 3.

As shown in FIG. 4, the cavity mold 4 has a slightly arcuate arc portion 22, and the mold surface on the side having this arc portion 22, that is, the cavity mold 4, is supplied with pre-expanded particles 13 of raw material. A filling port 1-4 of a feeder 15 is provided, and the feeder 15 has a raw material inlet 16 and a raw material passage 17 communicating therewith. The raw material passage 17 communicates with the filling port 14, and a piston 20 consisting of a tip 18 and a shaft 19 is slidably inserted into the raw material passage 17. 21 is configured to close the filling port 14 during molding. This closed state of the piston 20 and the filling port 14 is shown in detail in FIGS. 3 and 4. In FIG. 3, the upper end of the tip surface 21 of the piston 20 is aligned with the inner surface of the cavity mold 4.

The lower end is slightly inserted into the molding chamber 11, and in FIG. 4, both upper and lower ends of the tip surface 21 of the piston 20 are slightly inserted into the molding chamber 11.

Further, the cavity disk 4 is provided with an eject pin 6, and the distal end surface 7 (FIG. 1) of the eject pin 6 is in the state shown in FIGS. 3 and 4, similar to the distal end surface 21 of the piston 20. It is set to position. If the piston 20 and eject pin 6 are positioned as described above,
Since no gap is formed between the tip surfaces 21.7 and the arcuate portions 22, no protrusions are formed in the bumper core material 12 obtained by in-mold molding of the pre-expanded particles, and some recesses are formed. A skin material 23. is only formed on the surface of the core material 12. The mounting plate 24 can be easily mounted.

To actually manufacture the core material 12 for pants shoes using the mold 1 described above, the piston rod 10 is operated to fit the core mold 5 into the cavity mold 4, and the tip of the eject pin 6 is inserted. The surface 7 is positioned inside the mold from the arcuate portion 22 as shown in FIG.
After passing through the filling port 14 and being introduced into the molding chamber 11, the piston 20 closes the filling port 14. At this time, the tip end surface 21 of the piston 20 is positioned inside the mold from the arcuate portion 22 as shown in FIG. 3 or 4. Thereafter, the pre-expanded particles 13 are heated and foamed using an appropriate heating medium to obtain the core material 12 for a bumper.

The bumper core material 12 obtained by the manufacturing method of the present invention has a skin material 23 as shown in FIG. It can be used as a bumper 25 by attaching a mounting plate 24, etc., and has excellent energy absorption performance and dimensional recovery.

It satisfies the performance requirements for bumpers, such as being lightweight.

The present invention is not limited to the case where the mold surface has an arcuate portion, but is similarly applicable to the case where the mold surface has an inclined portion.

Further, the present invention is not limited to the case where the arcuate portion or the inclined portion is formed on the entire mold surface, but also includes the case where the circular arcuate portion or the inclined portion is formed on one part. In the latter case, for example, if the mold surface has a circular arc part and a flat part, and if both the eject bin and the feeder are provided in the circular arc part, the tip of the eject bin and the tip of the piston of the feeder, as described in the above example, is positioned inward of the mold from the arc part.

On the other hand, if one of them is provided on the circular arc part and the other on the flat part, the eject bottle tip or the feeder piston tip located in the second circular arc part is positioned inside the mold from the circular arc part. Align the tip of the piston or eject pin of the feeder located at the inner surface of the mold.

As explained above, according to the manufacturing method of the second invention, an in-mold molded body without any protrusions on the surface can be obtained. Therefore,
When applying the molded body as a core material for a bumper, for example, when attaching a skin material to the molded body, the fitting tolerances will be affected by the protrusions, making installation impossible or causing defective products. The effect of the present invention can be fully demonstrated especially in the manufacture of core materials for bumpers with strict dimensional accuracy, and the resulting core materials for bumpers have the performance required as core materials for bumpers. This fully satisfies the following.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view showing a conventional method for manufacturing an in-mold body, Figs. 2 to 5 show embodiments of the present invention, and Fig. 2 is an example of a mold used in the present invention. FIG. 3 is a longitudinal sectional view of the main part of FIG. 2. FIG. 4 is a vertical cross-sectional view of main parts showing another embodiment of the present invention. FIG. 5 is a partially cutaway perspective view showing a state in which the in-mold molded body obtained by the present invention is applied to a bumper. 1----One mold 6----Eject pin 7-
----- Tip surface of eject pin 12 ----- Core material for bumper 13 ------ Support foam particles 15 --- Feeder 20 ----- Piston 21 ----- Tip surface of piston 22 - One circular arc Fig. 3 Fig. 4 Fig. 5

Claims (1)

[Claims] two mold surfaces, an arcuate portion or an inclined portion formed in all or part of at least one of the mold surfaces, and an eject pin at least one of which is provided in the arcuate portion or the inclined portion of the mold surface. and a feeder, the mold is filled with pre-expanded thermoplastic resin particles, heated and foamed to obtain a molded product according to the mold. In-mold molding, characterized in that the tip of the eject pin and/or the tip of the piston of the feeder provided on the arcuate or inclined part of the mold surface is positioned inward of the mold than the arcuate part or the inclined part. How the body is manufactured.