JPS6031940A - Manufacture of bumper made of synthetic resin - Google Patents

Abstract

PURPOSE:To reduce weight per square meter and mass-produce the titled bumper by molding a hollow structure, in which two bumpers are opposed, by dies through blow molding, removing a cutting allowance and enabling a blow molding methd, the cost of the dies therefor is low, through a manufacture by in a split-into-two manner. CONSTITUTION:In blow molding in which a parison is poured from a die and air is blown into the parison while a molding material is molded by dies, the dies 6, 6 are united while using cut surface as borders in bumpers 1, 1' to be obtained, and a hollow structure 7 connected while interposing cutting allowances 8 is formed. When the hollow structure 7 is obtained by the dies 6, 6 and the cutting allowances 8a-8c are removed properly while the structure 7 is split into two as shown in a cutting-plane line A, two bumpers 1, 1' made of synthetic resin can be acquired at a time. Accordingly, obtained products take a single wall type and display the effect of the reduction of weight per square meter have few man-hours because two pieces can be molded simultaneously at a time, and can be mass-produced rapidly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a synthetic resin bumper for use in automobiles.

The recent trend is to make synthetic resin bumpers thinner to reduce their weight, and the impact strength is mainly achieved by a steel plate located on the back side, while the resin part is only required to have resilience.

On the other hand, most conventional synthetic resin bumpers are made by injection molding, which has the drawback of high mold costs and the inability to sufficiently respond to a wide variety of products in small quantities. On the other hand, if the blow molding method is used, the cost of the mold will be low, but the bumper itself will have a double wall structure or a hollow structure, which goes against the requirement of reducing the date. The cycle time is inferior to that of the previous model, and it is not profitable unless it is for small-scale production. Furthermore, in the double wall structure, it is extremely difficult to integrally mold the bent portions of the bumper corners.

The purpose of the present invention is to eliminate the disadvantages of the conventional example, to reduce costs by using an inexpensive mold in the blow molding method, and to reduce the above-mentioned area weight by using a single wall type bumper as a product. It is an object of the present invention to provide a method for manufacturing a synthetic resin bumper that satisfies the demands for improved design, diversity in design, and ease of manufacture, and can also greatly reduce the number of steps and can be mass-produced at low cost.

However, according to the present invention, the purpose of the lever is that when manufacturing by blow molding, the hollow structure to be molded with a mold is one in which two bumpers to be obtained are merged with the cut surface as the boundary, and the cutting allowance is reduced. This is achieved by dividing the hollow structure into two parts while removing the product.

Embodiments of the present invention will be described in detail below with reference to the drawings.

First, an example of a bumper manufactured by the method of the present invention will be described first.

As shown in Figures 1 to 3, the bumper 1 is of a single wall type made of synthetic resin, and the left and right end corners 1a are largely curved backwards, and the lower half is tilted backwards, and the bumper 1 is of a single wall type made of synthetic resin. On the contrary, the installation part is curved so as to protrude forward, and the spoiler 1b is integrally formed here. Further, circular boss type bolt attachment holes 1c were formed in the corner portions 1a, recesses 1d for attaching lamps were formed on the left and right sides of the front, and an air intake port 1e consisting of a horizontally elongated hole was formed in the center of the front.

In FIG. 3, 2 is a reinforcement into which the bumper 1 is fitted, and 3 is a stay for attaching the bumper 1 and the reinforcement 2 to the vehicle body. To explain in more detail how to attach the bumper 1 to the force 2, the corner part 1a is bolted using the hole 1c, and the upper surface is fixed with a rivet 4 as shown in FIGS. 4 and 5.
At the bottom, overlap the opening edge of the air intake port 1e and the opening edge of the reinforcement 2, tighten the fit-in nut 5, and tighten the bolt I. In the illustrated example, the outer surface of the reinforcement 2 and the inner surface of the bumper 1 have substantially the same shape and are in close contact with each other.

Although the shape of the bumper 1 is not necessarily limited to the above-mentioned shape, the method of the present invention for manufacturing such a single wall type bumper 1 will be described next.

FIG. 6 is a sectional view showing an embodiment of the method of the present invention. In blow molding, a parison is poured from a die and air is blown into the parison.
, 6 is such that a hollow structure 7 can be formed by merging the bumpers 1.11 to be obtained along the cut surfaces as shown in FIGS. 7 to 9 and connecting them with a cutting margin 8 interposed therebetween. . It is thought that the bumper 1°1" may be completely symmetrical and merged, or it may be approximately symmetrical with slightly different shapes,
- For example, the cutting allowance 8 is 8a, 8b on the ceiling surface and the lower end surface.
Assume that there are 80 at the left and right ends.

The material of the parison, that is, the synthetic resin of the hollow structure 7, may be a thermoplastic resin that can be blow molded, high-density polyethylene, medium-low density polyethylene, polypropylene, propylene-ethylene block or random copolymer, or high-density polyethylene. Polyolefin resins such as mixtures with polypropylene or high-density polyethylene, mixtures of polypropylene and amorphous ethylene-α-olefin copolymers such as ethylene-propylene rubber, ethylene-butene-1 rubber, etc., and polyvinyl chloride.

Vinyl chloride resins such as vinylidene chloride, polystyrene,
Examples include styrene resins such as acrylonitrile-styrene copolymer and acrylonitrile-butadiene-styrene copolymer, polyamide resins, polyester resins, and polyether resins, such as Noryl (trade name).

Generally, a long parison of about 1.5 m or more is required, so a material with excellent drawdown resistance is required.
, polypropylene thread 4Ai resin (MIo, 1 or less) and olefinic elastomer 7-1 filled with filler as a reinforcing agent are most suitable.

A hollow structure 7 is obtained using the mold 6.6, and the cutting allowance 8a is
By removing portions 8c and 8c as appropriate and dividing it into two parts as shown by cutting line A in FIG. 9, two synthetic resin bumpers 1.11 can be obtained at once. In addition, in this embodiment, the parting line B of the molds 6, 6 was made to coincide with the cutting surface indicated by the cutting line A, but as shown in FIG. Alternatively, it may be placed in front of 1'.

It is also conceivable to increase the strength by forming ribs on the back side of the bumpers 1 and 11. FIG. 11 shows an example of the case in which this rib raising is performed. In addition to the mold, a movable blade 10 is provided which is driven by a hydraulic cylinder rod 9, slides within the mold, and whose tip protrudes inward.

When the parison poured from the goo is sandwiched between molds and air is sent into the interior, if the blade 10 is extended before the parison begins to solidify, the parison will also be pushed, and then the blade 10 can be moved back. These parts are fused together to obtain a hollow structure 7'' which is plate-shaped and has reinforcing ribs 1h integral with the bumper 1.11 of the main body.

Figure 13 shows a 7° hollow structure with ribs made using another method.
As shown in the vertical cross-sectional view of °, it is also possible to form irregularities on the mold in advance, and form boss-type ribs 1g with the irregularities on the sides.

When these ribs Lh and Ig are provided, the ribs will be provided in parallel to the longitudinal direction of the bumper, and will function as a continuous beam for the stays and reinforcements, and can sufficiently cope with strong impacts. Stay strong.

As mentioned above, the method for manufacturing the synthetic resin bumper of the present invention adopts the blow molding method with low mold cost, and the resulting product is a single wall type, which has a sufficient effect of reducing the date. Since two pieces can be molded at the same time, the number of steps is small, and mass production is possible easily, quickly, and at low cost.

[Brief explanation of drawings]

Fig. 1 is a side view showing how the bumper obtained by the method of the present invention is used, Fig. 2 is a front view of the bumper, Fig. 3 is a cross-sectional plan view showing the bumper as it is added, and Fig. 4 is a front view of the main parts of the same. Figure 5 is a sectional view taken along the line B-B in Figure 4, Figure 6 is a cross-sectional explanatory diagram showing the first embodiment of the method of the present invention, and Figure 7 is a molded product formed by the method shown in Figure 6. A plan view of the hollow structure, FIG. 8 is a front view, FIG. 9 is a cross-sectional view taken along line A-A in FIG. 7, FIG. 10 is a cross-sectional explanatory view showing a second embodiment of the present invention, and FIG. 12 is a vertical cross-sectional side view showing a method of rib-standing, FIG. 12 is a vertical side view of a hollow structure with ribs raised, and FIG. 13 is a vertical side view showing another example of a hollow structure. 1.11... Bumper 1a... Corner part 1b.
... Spoiler - 1c... Bolt mounting hole 1d... Four parts for lamp mounting 1e... Air intake port 1h, Ig... Rib 2...
Reinforce 3... Stay 4... Rivet 5
... Nut 6 ... Mold 7.7", 7" ... Hollow structure 8.8a to 8c ... Cutting allowance 9 ... Cylinder rod 10 ... Movable blade applicant Tonen Petrochemical Co., Ltd. Procedural Amendments Commissioner of the Patent Office Kazuo Wakasugi 1, Indication of the case 1981 Patent side No. 138966 2, Name of the invention Method for manufacturing synthetic resin bumpers 3, Person making the amendment 4, Address of the agent No. 7-14 Mejiro-chome, Toshima-ku, Tokyo Invention specification, page 6, line 2, rO, IJ, rl, O
Correct it with J.

Claims (1)

[Claims] In the case of manufacturing by blow molding, the hollow structure to be molded with a mold is obtained by merging two bumpers to be obtained with the cut surface as the boundary, and the hollow structure is divided into two while removing the cutting allowance. A method for producing a synthetic resin bumper, characterized in that the product is obtained by