JPS6334257A - Manufacture of soft molding - Google Patents

Abstract

PURPOSE:To prevent deformation of a skin body and to reduce the weight of a molding, by a method wherein the skin body having a hollow part is previously formed by using soft resin, and thereafter the hollow part is filled with a resin foaming material. CONSTITUTION:An outer surface is formed in a given molding shape, and a skin body 1 having a hollow part 10 is formed. A foaming resin material consisting of polyurethane resin is injected in a condition in that the skin body 1 is placed in a blow molding tool, and after the material is foamed and cured, a moulded prod is taken out. This method forms a resin foam 2 with which the skin body 1 is densely filled. Thus, since, during injection, strength of the skin body is high, even if foaming resin is foamed in the skin body, the skin body can be prevented from deformation.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of manufacturing moldings such as υid moldings attached to the side of an automobile body and bumper moldings attached to a bumper. The present invention relates to a method of manufacturing a molding having a molding.

[Prior Art] In recent years, there has been a demand for lighter weight automobiles, and there is also a desire for lighter moldings. A common way to reduce the weight of a molding is to make the inside hollow. However, in the case of soft moldings, it is often difficult to maintain the shape if the molding is hollow. Therefore, a soft molding having a foam inside the L-ru has been developed.

By the way, such a molding with foam inside is va
Conventionally, the skin resin and foamed resin are extruded in two colors, the foaming agent in the cylinder of the extruder is decomposed, and the foam is released by releasing pressure at the exit of the die, or extrusion foaming is used. This is done by injecting foamed resin and heating it with high frequency waves to foam it.

[Problems to be Solved by the Invention] In conventional extrusion foam molding, the shape retention of the skin is not maintained when the foam is highly foamed, so the specific gravity is approximately 0.
．． The weight of the foam was limited to about 8 to 1, and there was a limit to the weight reduction. Further, the foam is exposed at the ends of the obtained molded body, and in order to treat the ends, only the ends are formed by injection molding or the like. However, in this case, the processing of the boundary between the injection molded part and the extrusion molded part is troublesome, requires a lot of man-hours, and the appearance is not good. In addition, even in heat foam molding, if the foaming is increased to a high level, the surface smoothness is impaired, so that only a foam having a specific gravity of around 1 can be obtained, and there is a limit to the weight reduction.

The present invention has been made in view of the above-mentioned problems, and provides a method for easily manufacturing a molding having a highly foamed material inside.

[Means for Solving the Problems] The method for manufacturing a soft molding of the present invention includes a first molding step of molding a skin body whose outer surface has a predetermined molding shape and a hollow portion from a soft resin, and resin foaming. The method is characterized by comprising a filling step of filling the hollow portion with a body.

The first molding step is a step of molding a skin body having a predetermined molding shape from a soft resin. Here, as the soft resin, soft resins such as soft polyvinyl chloride resin, polyethylene, and ionomer-modified polypropylene can be used. This first formed J culm can also be performed by forming a cylinder by extrusion molding. However, in this case, a separate step of molding the end portion is required after the filling step, which will be described later.

Therefore, this first molding step is preferably performed by blow molding. According to blow molding, the end portion can be molded at the same time in this first molding step.

The filling step is a step of filling the inside of the skin body obtained above with a resin foam. This filling process = 4
- It can also be carried out by press-fitting a resin foam shaped into the hollow part of the child skin body into the hollow part. However, in this case, it is necessary to perform two steps: molding the resin foam and press-fitting it into the skin. Therefore, it is desirable to fill the skin by injecting the foamed resin into the hollow part of the skin body and avoiding foaming in the hollow part. In this way, the processes corresponding to molding and press-fitting the resin foam can be performed simultaneously, which is efficient.

Furthermore, the integrity of the skin and the resin foam is improved.

When foaming is performed inside the skin body, the filling process can be performed separately into an injection process and a second molding process. In the injection step, it is desirable to place the skin in a mold and then inject the foamed resin into the hollow part of the skin. In this way, the shape of the skin body is reliably maintained. In this case, if the skin is to be molded by blow molding, it is preferable to use the blow mold as it is. In addition, if the skin body has a strength greater than that capable of maintaining shape retention, this can be done without placing it in a mold. Then, in the second molding step, the foamed resin is foamed in the hollow part, and a resin foam that fills the hollow part by =5- is formed.

As the foamed resin to be used, polyurethane resin, polystyrene, polyethylene, polypropylene, etc. can be used. Since the skin is prevented from deforming, the foaming ratio can be high, and the foam can have a specific gravity of 0.05 to 0.6 degrees, for example.

In addition, as a foaming method, conventional methods such as adding a foaming agent such as chlorofluorocarbon, methylene chloride, or butane, or using a reaction product gas such as carbon dioxide produced by the reaction of water and isocyanate may be used. Can be adopted.

[Operations and Effects of the Invention] In the manufacturing method of the present invention, a skin body having a hollow portion is molded from a soft resin in advance, and then the hollow portion is filled with a resin foam. Therefore, since the strength of the skin is high during filling, deformation of the skin can be prevented even if the foamed resin is foamed inside the skin, and shape retention is excellent even when the expansion ratio is higher than before. Therefore, according to the manufacturing method of the present invention, the interior can be formed from a highly expanded resin foam, and the weight can be significantly reduced compared to the conventional method. Further, when a pre-formed resin molded body is press-fitted into the skin body, the expansion ratio of the resin molded body can be freely set. Therefore, it is possible to significantly reduce the weight compared to the conventional one.

Furthermore, if the skin body is formed by blow molding, there is no need to perform end treatment of the molding, reducing the number of man-hours and improving the appearance. Further, since the resin foam can be molded in succession to the blow molding, it is efficient.

[Example] This will be explained in detail below using examples.

<First molding process> Using two sheets of soft vinyl chloride resin,
After being heated and softened, the entire periphery was sandwiched between molds and welded, and placed in a blow molding mold. Then, pressurized air is introduced between the two sheets of material at a pressure of 6 kQ/Cm2, and the sheet material is pressed against the mold surface to perform blow molding, and the outer surface is kept constant at -7 as shown in Figure 2. A skin body 1 having a molded shape and having a hollow portion 10 was molded. At this time, pressurized air was introduced from the back side of the molding, and both ends of the molding were formed into a predetermined bag shape.

(Filling process) Next, with the skin body 1 placed in the blow molding mold, foamed wood 111i material made of polyurethane resin to which a foaming agent has been added is injected through the hole into which pressurized air is introduced, and the material is heated at about 40°C. The foamed resin material was foamed by heating for 5 minutes. After the foamed resin material was foamed and solidified, the mold was removed (7i1) and the molded product was taken out.

As shown in Fig. 1, the obtained molded body has a resin foam 2 densely filled inside the skin 1, and the specific gravity of the resin foam 2 is 0.3, and the molding of pumice is Obtained. The terminal part of the molding was integrally molded with the other parts, giving it an excellent appearance quality.

In addition, according to the manufacturing method of this example, the third molding process is performed in the first molding process.
It is also possible to form a skin body 4 having a glittering layer 3 made of aluminum as shown in the figure.

Also, as shown in Figure 4, the molding for clipping,
It is also possible to form a skin body 7 having a clip seating surface 6 in which an insert 5 is embedded. Then, by foaming the foamed resin within the skin body 7 in the same manner as described above, a lightweight molding can be easily manufactured.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1 and 2 are diagrams relating to a manufacturing method according to an embodiment of the present invention, in which FIG. 1 is a partial perspective view showing a partial cross section of the molding obtained, and FIG. The figure is a partial perspective view showing a partial cross section of the skin body 19 formed in the first molding step. Figures 3 and 4
The figure is a sectional view showing another example of the skin body produced by the manufacturing method of the embodiment. 1.4.7...Skin body 2...Resin foam 3...
・Glitter layer 5...Insert 6...Clip seating surface 10...Hollow part Patent applicant Toyoda Gosei Co., Ltd. agent Patent attorney Hiroshi Okawa Figure 1 Figure 2

Claims (5)

[Claims] (1) Manufacture of a soft molding comprising: a first molding step of molding a skin body having a predetermined molding shape on the outer surface and a hollow portion from a soft resin; and a filling step of filling the hollow portion with a resin foam. Method. (2) The method for manufacturing a soft molding according to claim 1, wherein the first molding step is performed by blow molding. (3) The filling process includes an injection process in which the skin body is placed in a mold and foamed resin is injected into the hollow part of the skin body, and a second process in which the foamed resin is foamed to form a resin foam that fills the hollow part. A method for manufacturing a soft molding according to claim 1, which comprises a molding step. (4) The method for manufacturing a soft molding according to claim 1, wherein the filling step is carried out by press-fitting a resin foam previously formed into the shape of the hollow part of the skin body into the hollow part. (5) The method for manufacturing a soft molding according to claim 1, wherein the resin foam is a high foam having a specific gravity of 0.05 to 0.6.