JPH0716876A - Sandwich molded article having rib - Google Patents

Abstract

PURPOSE:To obtain a sandwich molded article on the design surface of which no core line occurs and which has a rib. CONSTITUTION:In a sandwich molded article which is formed of a core material 2 and a skin material 1 applied on the surface of the core material and has a rib 3 projecting from the main body, the rib 3 has a free flow end 31 having an acute angle or the shape of a round head in the rear end part of a resin flow at the time of molding. When the core material 2 is injected subsequently to the skin material 1 at the time of molding of a sandwich molded article, the core material 2 flows smoothly even in the rear of the rib 3, since a subcavity for molding the rib 3 has the same free flow end as the aforesaid free flow end. Therefore no core line occurs on the design surface of the sandwich molded article.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sandwich molded article having ribs such as an over fender which is a part for automobiles.

[0002]

2. Description of the Related Art As a synthetic resin molded product, a sandwich molded product is known in which a core material is formed on the inside and a skin material is formed on the surface thereof (Japanese Patent Laid-Open No. 2-206518). This product is integrally molded of synthetic resin and has a relatively hard core material inside and a relatively soft skin material on the surface. Therefore, it has the excellent properties that the surface is soft and the overall rigidity is high.

Such a sandwich molded product has ribs for locking fittings such as metal fittings and screws, and is attached to a mating member via these ribs. For example, in FIG.
As shown in FIG. 2, taking the over fender 9 provided on the vehicle body above the front wheels of the small truck 99 as an example, this is a long arc-shaped long molded product. In addition, as shown in FIG.
The over fender 9 has a rib 91 on the back side of the main body 90 for locking the attachment.

By the way, when the above-mentioned over-fender 9 is constructed by a sandwich molded product, as shown in FIG. 13, the main body 90 is composed of a synthetic resin core material 2 and a synthetic resin skin material 1 coated on the surface thereof. Formed by and. As shown in FIG. 15, the rib 91 is mainly formed of the skin material 1, and has the core material 2 integrally formed with the core material 2 in the main body 90 below the skin material 1.

Further, when the sandwich molded article is molded, a molding die provided with a discarding tab in front of a cavity for forming the rib 91 is used (not shown). Then, the skin material is injected into the molding die, and then the core material is injected into the skin material. During rib formation, excess skin material flows out into the discarding tab through a small flow path.

As a result, as shown in FIG. 15, a main body 90 and a rib 91 are molded, the interior of which is a hard core material 2 and the surface of which is covered with a soft skin material 1. Note that Fig. 1
In the rib 91 of the sandwich molded product, a tab product 95 formed by the aforesaid tab and a small flow path product 951 formed by a small flow path are shown at the tip of the rib 91. These tab product 95 and small flow channel product 951 are integrally formed when the sandwich molded product is taken out from the molding die, but are removed thereafter.

[0007]

[Problems to be Solved] However, the conventional sandwich molded article has the following problems with respect to its ribs.
That is, the over fender 9 also plays a large role in improving the design of the automobile. Therefore, the design surface 7 which is easily noticeable is required to have particularly good appearance. This design surface means the front surface side of the over fender 9 and is the surface opposite to the surface (rear surface side) where the ribs 91 are provided (FIG. 16).

However, the conventional over fender 9 is shown in FIG.
As shown in FIG. 6, two core lines 71 are generated on the downstream design surface 7 of the rib 91 in the flow direction Y (FIGS. 14 to 16) of the skin material and the core material. The core line 71 is formed in a shallow concave shape on the downstream side of the root of the rib 91.

The occurrence of such a core line 71 is considered to be due to the following reason. That is, during sandwich molding, the core material 2 injected from the gate of the molding die (position 96 in FIG. 12) slightly flows into the inside of the rib 91 in the portion where the rib 91 is formed. for that reason,
The core material 2 is divided near the root of the rib 91, and the core material 2 does not flow on the downstream side of the rib 91 (FIGS. 13 to 15). Therefore, a sink mark is generated on the upper surface (design surface) divided as described above, and two concave core lines 71 are generated.

Further, the core line 71 can be seen immediately after the overfender is sandwich-molded, but when a coating for improving the design is further applied to the surface of the overfender 9, the core line 71 becomes more conspicuous and the appearance is improved. Make it worse. This is a common problem not only in overfenders but also in sandwich molded products having ribs. In view of the above conventional problems, the present invention aims to provide a sandwich molded product having ribs, in which the core line does not occur.

[0011]

The present invention provides a sandwich molded article comprising a synthetic resin core material and a synthetic resin skin material coated on the surface thereof and having ribs protruding from the main body. A sandwich molded article having ribs is characterized in that a rear end portion of the flow has a free-flowing end having an acute angle or a circular head shape.

The most remarkable point in the present invention is that the rib of the sandwich molded article has the free-flow end at the rear end of the resin flow. The resin flow rear end means the rear end of the rib in the direction in which the synthetic resin flows during the molding of the sandwich molded product. The easy flow end is formed at the rear end of the resin flow. The shape of the free-flowing end includes an acute angle and a circular head shape (Fig. 1,
(Figure 6). In the case of the latter circular head shape, the circular head preferably has a radius of curvature of R / 2 to R / 5 of the width R of the rib. If it is larger than R / 2, it is difficult to obtain the effect of the present invention. On the other hand, if it is less than R / 5, there is a problem in the machining accuracy of the mold. Note that R is 1.0 to 5.0 mm.

The ribs may be in the form of a horizontally elongated protrusion (FIG. 1) or a trapezoid having a forked leg (FIG. 7), H.
There is a shape body (FIG. 9) and the like. The forked legs of the latter two are
The easy end is provided. The ribs are mainly formed of a skin material, and the lower portion thereof is filled with a core material (see FIG. 3). On the other hand, the main body provided with the ribs has a sandwich structure including a core material and a skin material coated on the surface thereof.

As the core material, a hard ABS resin,
Examples include hard PVC resin and polypropylene resin containing filler such as talc. Also, there are resins in which glass fibers and the like are mixed with these resins. As the skin material, resin made by blending EPDM with soft polypropylene, EVA resin, SEBS (styrene-ethylene-
Butylene / styrene) resin, SBS (styrene / butadiene / styrene) resin, or soft PVC resin.

Next, when manufacturing the sandwich molded article, a molding die having a cavity for molding the main body and a sub-cavity communicating with the cavity and molding the rib is used. The cavity has the same shape as the rib having the free-flowing end.

[0016]

In the sandwich molded article of the present invention, the main body has a sandwich structure, and the rib has the free-flowing end at the rear end of the resin flow. Therefore, at the time of molding, the skin material existing below the rib forming sub-cavity before the core material is injected is easily pushed by the flow of the injected core material and is easily moved to the downstream side. It is difficult for the flow to be divided (see FIGS. 2 and 3).

That is, the downstream side of the sub-cavity (resin flow end) has the free-flow end. for that reason,
When the skin material is pushed downstream by the injection of the core material,
The skin material flows along the free flowing end of the rear end of the resin flow. The free stream end has an acute angle or a round head at the rear. Therefore, the skin material is pushed by the core material flowing from both sides behind the free-flowing end and finally cut.

Therefore, the core material is sufficiently filled behind the ribs. Therefore, the core line as shown in the conventional example does not occur. In addition, the main body of the sandwich molded product combines the excellent properties of surface rigidity and internal rigidity inherent in the sandwich structure. Therefore, according to the present invention, it is possible to provide a sandwich molded product having ribs and a molding method thereof, in which the core line is not generated.

[0019]

【Example】

Example 1 A sandwich molded article according to an example of the present invention will be described with reference to FIGS. As shown in FIG. 5 and FIGS. 11 and 12, the sandwich molded article of this example is an over fender 9 mounted on the vehicle body above the front wheels of a small truck.

Further, as shown in FIG. 1, the main body 90 of the over fender 9 has a sandwich structure composed of a synthetic resin core material 2 and a synthetic resin skin material 1 coated on the surface thereof. On the other hand, the rib 3 has a free-flowing end 31 having an acute angle at the rear end portion of the resin flow at the time of molding. Further, as shown in FIG. 3, the rib 3 is mainly formed of the skin material 1, and the core material 2 is filled inside the lower portion thereof.
It should be noted that the rib 3 has a tab product 9 at the time of molding as in the conventional example.
5. The small flow path product 951 is molded (see FIG. 15), but these are cut and discarded.

In this example, a polypropylene resin containing glass fiber of a hard synthetic resin was used as the core material.
On the other hand, as the skin material, SEBS resin which is a soft synthetic resin was used. Next, in manufacturing the sandwich molded product, a molding die having a cavity for molding the main body 90 and a sub-cavity for communicating with the cavity and for molding the rib is used (not shown).
The shapes of the cavities and the sub-cavities are the same as the outer shapes of the main body and the ribs.

Then, the skin material 1 is injected from the gate into the above-mentioned molding die by a conventional method, and then the core material 2 is put therein.
Inject. Both synthetic resins flow in the direction of the arrow Y shown in FIGS. At this time, first, the skin material 1 flows forward in the cavity for forming the main body, and a part thereof also enters the sub-cavity for forming the rib. Next, the core material injected into the skin material flows forward.

On the other hand, the mold subcavity has a free-flow end similar to the free-flow end 31. Therefore, at the time of molding, the skin material existing inside and below the sub-cavity before the core material is injected is easily pushed by the flow of the injected core material and easily moves to the downstream side. Therefore, the flow of the core material is not divided as in the conventional case.

That is, as shown in FIGS. 2 and 3, the resin flow rear end of the sub-cavity has the free-flow end 31. Therefore, when the skin material 1 is pushed to the downstream side (direction of arrow Y in FIGS. 1 to 3) by the injection of the core material 2,
The skin material 1 flows along the free flowing end 31 at the rear end of the resin flow. The easy flow end 31 has an acute angle at the rear.

Therefore, the skin material 1 located under the sub-cavity is pushed by the core material 2 flowing from both sides behind the free-flow end 31 and finally cut. Therefore, the core material is sufficiently filled even behind the ribs. Therefore, the core line as in the conventional example does not occur. That is, as shown in FIG. 4, in the main body 90 of the sandwich molded article of this example, the design surface 7 is smooth and no core line (FIG. 16) is generated.

As shown in FIG. 2, a small amount of skin material 10 remains on the lower portion of the rib 3 and on the side thereof.
This skin material 10 is a skin material 1 that is inside the rib 3.
When they are cooled, they are cooled together and remain in this part. Further, as shown in FIG. 5, the rib 3 is arranged so that the free-flow end 31 at the rear end of the resin flow is located in the direction opposite to the gate position 96. This figure shows an example of the arrangement of the two ribs 3 and their free-flowing ends 31. As described above, according to this example, it is possible to easily manufacture the over fender without the occurrence of the core line.

Example 2 This example shows various shapes of the free-flow end provided on the rib as shown in FIGS. That is, in FIG. 6A, the free-flowing end 321 has a radius of curvature (R / R) that is 1/2 of the width R of the rib 32.
2).

Further, in FIG. 6 (B), the free-flowing end 331 has a radius of curvature (R / 3) which is 1/3 of the width R of the rib 33. Further, in FIG. 6C, the free-flowing end 341 has a radius of curvature that is ⅕ of the width R of the rib 34. In any case, the same effect as that of the first embodiment can be obtained.

Embodiment 3 This embodiment shows an example in which a trapezoidal rib 35 is provided as shown in FIGS. The rib 35 includes a bifurcated leg 353 standing on the main body 90 of the over fender 9 and a pedestal 354 provided on the upper surface. The pedestal 354 has a clip hole 355 for inserting a mounting clip. The bifurcated leg portion 353 has an arc-shaped free-flowing end 351 at the rear end of the resin flow. Others are the same as in the first embodiment.

Also in this example, as shown in FIG. 8, when the skin material 1 is pushed to the downstream side by the injection of the core material 2,
The skin material 1 flows along the free flowing end 351 at the rear end of the resin flow. Therefore, behind the free-flowing end 351, the skin material 1 is cut by the core material 2 flowing from both sides, and the core material 2 is sufficiently filled also behind the rib 35. Therefore, no core line is generated. In addition, the same effect as that of the first embodiment can be obtained.

Embodiment 4 In this embodiment, as shown in FIGS. 9 and 10, an H-shaped rib 36 is formed.
An example in which is provided is shown. The rib 36 includes a bifurcated leg portion 363 that is erected on the main body 90 of the over fender 9 and a connecting portion 365 that connects the two. Bifurcated leg 3
The lower end 364 of 63 has a smaller width than the upper end. Further, each of the lower ends 364 has a resin flow trailing end which has an arc-shaped free-flow end 361. The width of the lower end 364 of the bifurcated leg 363 is about 1.0 mm, and the width of the upper end thereof is about 1.5 mm. Others are the same as in the third embodiment.

Also in this example, the same effect as that of the third embodiment can be obtained. Further, in this example, since the width of the lower end portion 364 of the bifurcated leg portion 363 is reduced as described above, it is possible to further prevent the generation of the core line.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of the vicinity of a rib of an over fender according to a first embodiment.

FIG. 2 is an explanatory diagram of a synthetic resin flow in the vicinity of ribs in the first embodiment.

3 is a sectional view taken along the line AA of FIG.

FIG. 4 is an explanatory view of a design surface of the sandwich molded article of Example 1.

FIG. 5 is a perspective view of a main part of the over fender according to the first embodiment.

FIG. 6 is an explanatory view of various shapes of a free-flow end in the rib of the second embodiment.

FIG. 7 is a perspective view of the vicinity of the rib in the third embodiment.

FIG. 8 is an explanatory view of the flow of synthetic resin in the vicinity of ribs in the third embodiment.

FIG. 9 is a perspective view of the vicinity of the rib in the fourth embodiment.

FIG. 10 is an explanatory view of the flow of synthetic resin in the vicinity of ribs in Example 4.

FIG. 11 is a side view of a conventional light truck.

FIG. 12 is a perspective view near a rib of an over fender in a conventional example.

FIG. 13 is an explanatory diagram of the vicinity of a rib of an over fender in a conventional example.

FIG. 14 is an explanatory view of a synthetic resin flow in the vicinity of a rib in a conventional example.

15 is a sectional view taken along the line BB of FIG.

FIG. 16 is an explanatory diagram of a core line on a design surface of a conventional overfender.

[Explanation of symbols]

1. ． ． Skin material, 2. ． ． Core material, 3, 32, 33, 34, 35, 36. ． ． Ribs, 31, 321, 331, 341, 351, 361. ． ．
Easy end, 7. ． ． Design aspect, 9. ． ． Over fender, 90. ． ． Body,

Front page continuation (72) Hiroshi Mukai, Hiroshi Mukai, Aichi Prefecture, Kasuga-cho, Aichi Prefecture Ochiai, Nagachibata No. 1, Toyoda Gosei Co., Ltd. In the company

Claims (1)

[Claims] 1. A sandwich molded article comprising a synthetic resin core material and a synthetic resin skin material coated on the surface thereof and having ribs protruding from the main body, wherein the resin flow rear end portion at the time of molding of the ribs is A sandwich molded product having a rib, which has a free-flowing end having an acute angle or a circular head shape.