JP3044682B2 - Mounting feet for roof rails for automobiles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin mounting leg of a roof rail to be mounted on a roof of a motor vehicle due to practical requirements of luggage transportation and / or decoration and design requirements.

[0002]

2. Description of the Related Art Automobiles use roof rails for carrying luggage such as surfboards and skis, or for decoration (for example, see Japanese Utility Model Laid-Open No. 2-114554).

[0003] In most cases, the mounting leg of a roof rail according to the prior art to a vehicle body is made of aluminum die-cast, urethane molding with a metal bracket inserted, or a combination of aluminum die-cast and resin cover.

However, in the case of an aluminum die-cast product, it is necessary to remove burrs generated during die-casting to finish a joint surface with a vehicle body and the like, and excessive labor and cost are required for deburring and polishing. Also,
Regarding the production weight, the specific gravity is 2.3, which is about twice as large as that of the resin, so that the weight becomes extremely large, which is contrary to the demand for weight saving for energy saving.

[0005] In the case of a urethane molded product in which a metal bracket is inserted, since the surface becomes orange peel, the appearance quality is inferior. Also, in the case of aluminum die cast covered with resin cover,
There was a problem that secondary processing was required for the assembling work.

In order to solve these problems, it is conceivable to form the mounting legs by injection molding using a thermoplastic resin. However, since the thickness of the product is too large, voids (bubbles) tend to be generated, resulting in a decrease in mechanical strength and appearance defects such as sink marks.

[0007]

SUMMARY OF THE INVENTION The present invention solves the drawbacks of the prior art and reduces the weight of a roof rail for an automobile by using a thermoplastic resin and manufacturing it by injection molding using gas-assisted injection. And the need for secondary processing such as deburring and polishing, and the need for secondary processing when assembling due to the integral molding of the legs, and the overall cost reduction of automotive roof rails. It is an object to provide a mounting leg made of a plastic resin.

[0008]

In order to solve the problems of the present invention SUMMARY OF THE INVENTION, automotive roof rail attachment leg portion of the mounting sealing surface of the outer circumference of the part for injecting resin resin gate (1
1, 21, 31) and gas gates (12, 22, 32) for injecting gas into the inside of the mounting seal surface, and the structure of the mounting leg of the roof rail for automobiles having a hollow portion inside the molded product. .

Further, an inert gas is injected into a mixed resin (PC / PBT resin) of polycarbonate and polybutylene terephthalate melted in the metal cavity, and the mixture is pressurized and held until the molten mixed resin is solidified. Forming a hollow inside the resin by degassing the gas,
By adopting the so-called gas assist injection molding method, the mounting legs of the roof rail for automobiles, which have excellent appearance quality with mechanical strength without sink marks by eliminating thick portions, were formed.

[0010] Further, the main body of the mounting leg is 10 ^-4 (sec ^-1 ).
The viscosity at the time of shearing is 90-150 Pa.sec, the viscosity at the time of shearing 10 ³ (sec ^-1 ) is 400-700 Pa.sec, and the viscosity at the time of shearing 10 ² (sec ^-1 ) is 1,000-2,000 Pa. The mounting leg of the roof rail for automobiles can be formed of a thermoplastic resin material having a viscosity of 1,500 to 3,000 Pa · sec when sheared at sec, 10 ¹ (sec ⁻¹ ).

[0011]

According to the present invention, at the time of injection molding of a thermoplastic resin, the molten resin is cooled and solidified in the metal cavity in the metal cavity. In this case, the inert gas injected changes the softened state of the thick part. Try to get inside the holding part. Therefore, the resin is pressed against the surface of the metal cavity and held, so that a hollow portion due to the inert gas is formed inside the wall portion, the wall thickness does not increase, and the gas pressure pushes the resin from the inside, so the appearance of sink marks etc. The occurrence of defects is prevented.

In order to perform such molding, a thermoplastic resin composition having the above-mentioned viscosity characteristics is advantageously applied.

As a result, it is possible to obtain a thermoplastic resin mounting leg for a roof rail for an automobile, which satisfies the requirements of weight reduction, appearance and the like and has excellent characteristics in terms of mechanical strength.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 and FIG. 2 are explanatory views showing a mounted state of a roof rail for an automobile.
1 ′ and the rail body 2.

FIGS. 3 (a) and 3 (b) are explanatory views showing the mounting leg 1 of the roof rail of the present invention. The mounting legs of the roof rail are a leg main body 1a and a rail main body mounting section 1.
b, mounting bolts 1c, and mounting seal surfaces 1d formed on the lower surface of the leg body 1a.

A resin gate 11 and a gas gate 12 are formed on the leg body 1a. Preferably, the resin gate 11 is set near one end of the leg body 1a, and the gas gate 12 is set within the mounting seal surface 1d.

Since the mounting leg 1 is injection-molded, the resin gate 11 is set with the mounting bolt 1c set in the mold.
After the molten resin is injected into the mold cavity from before, before the resin is completely filled in the mold cavity, the injection is temporarily interrupted and a short shot is made.

Then, the resin injected into the mold cavity is solidified because it is rapidly cooled by the mold only at the part in contact with the mold. Subsequently, a gas nozzle is inserted from the gas gate 12 provided in the sealing surface 1d, and an inert gas (for example, nitrogen gas) is guided to the thick portion through the gas channel GC which has not been solidified yet but is in a softened state. Was molded.

The pressure of the inert gas to be injected is 70 kg /
and cm ² ~150kg / cm ^2, 60sec~100s
After maintaining that state for ec, the inert gas is degassed.

Next, the mold is opened, and the mounting leg of the roof rail formed by the ejector is taken out of the mold cavity.

In the following embodiment of the present invention, PC / PBT resin (XEN) is used as a thermoplastic resin as a basic material.
OY1760, XENOY1730, XENOY178
0: Both are trademarks, Japan GE Plastics Co., Ltd.
3) was used.

These raw materials are melted and injected into the mold cavity, and the injection pressure of the inert gas, the holding time after the injection, the injection timing, etc. are changed, and the gas gates 12, 22 for injecting the inert gas are further changed. Experiments were performed with 32 different. The results of these experiments are as shown in Table 1. In addition, the negative number in the inert gas injection start time in Table 1 is:
This indicates that the process is started before the injection of the molten resin.

Example 1 FIG. 4 shows the shape of Example 1 implemented under the conditions shown in Table 1. The thermoplastic resin injected into the mold cavity from the resin gate 11 in FIG. The part in contact with the mold is immediately cooled and solidified. However, the high-pressure gas that has entered the cavity from the gas gate 12 that injects the high-pressure inert gas provided in the thick portion has not yet solidified in the gas channel GC, which is designed in advance and has a relatively large thickness. Since the gas reaches the thick portion through the passage and is held for a predetermined time, a hollow portion is formed in that portion.

[0024]

[Table 1]

Therefore, since there is a hollow part formed by gas pressure inside the thick part, the surrounding thickness becomes uniform, and the appearance defects such as sink marks on the surface do not occur.

Molded product A-A cross-sectional shape and B in FIG.
According to the -B cross-sectional shape, as shown in FIGS. 4 (a) and 4 (b), a hollow portion as expected at the beginning was formed.

Embodiment 2 FIG. 5 shows the shape of Embodiment 2 implemented under the conditions shown in Table 1. The molten resin is injected into the mold cavity from the resin gate 21 shown in FIG. From gas gate 22
An inert gas of 70 kg / cm ² is injected at a predetermined time after the injection of the resin. In addition, gas was simultaneously injected while continuing to inject the resin.

When the injection of the resin is completed, the injection of the gas is blocked.
Cut off and hold for 60 seconds. Next, the gas is degassed from the gas gate 22, the mold is opened, and the molded product is taken out.

As shown in FIGS. 5 (b) and 5 (c), the shape of the cross section taken along the line CC and the cross section taken along the line DD of the molded product shown in FIG. Had formed.

Embodiment 3 FIG. 6 shows the shape of Embodiment 3 performed under the conditions shown in Table 1. The molten resin is injected into the mold cavity from the resin gate 21 shown in FIG. Gas gate 32 to 1
Inert gas of 20 kg / cm ² is injected at a predetermined time after injection of the resin. In addition, gas was simultaneously injected while continuing to inject the resin.

When the injection of the resin is completed, the injection of the gas is blocked.
And hold for 100 seconds. Next, the gas is degassed from the gas gate 32, the mold is opened, and the molded product is taken out.

Also in this case, the E of the molded product shown in FIG.
The shape of the -E section and the shape of the FF section are shown in FIG.
As shown in (c), the hollow portion was formed as expected at first.

Table 2 shows the general properties of the thermoplastic resins used in the above examples.

[0034]

[Table 2]

[0035]

According to the present invention, a hollow structure having a uniform thickness distribution, such as an aluminum die-cast product, can be obtained because a product is obtained by a combination of thermoplastic resin injection molding and gas assist molding. Was. This product had a good appearance, no deburring polishing was required, and the cost was reduced.

The product thus obtained has a specific gravity of about one half of that of aluminum die-casting, since the material is a thermoplastic resin, and a significant reduction in weight can be achieved.

Since the product according to the present invention is manufactured by the combined use of injection molding and gas assist, even if it is a thick product, there is no sink mark or the like, and the mechanical strength is inferior to the aluminum die-cast product. Product can be obtained.

Since such a manufacturing method is essentially injection molding, a required structure can be integrally formed.
The assembling work using a plurality of parts can be eliminated.

Further, although the die of the aluminum die-casting is a life type, the injection molding die can be a permanent die, and the economic efficiency can be improved. In addition, since the material is a thermoplastic resin, there is no need to consider rust prevention as in the case of aluminum die casting. Since the gas gate is provided inside the sealing surface, traces of the gas gate can be provided without affecting the appearance.

[Brief description of the drawings]

FIG. 1 is a schematic view of an automobile to which a roof rail is attached.

FIG. 2 is a schematic view showing a state in which an automobile roof rail is mounted.

FIGS. 3A and 3B are a side view and a rear view showing a structure of a roof rail mounting leg.

FIGS. 4A, 4B and 4C are a rear view and a sectional view showing a structure of a roof rail mounting leg;

FIGS. 5A, 5B and 5C are a rear view and a sectional view showing the structure of a roof rail mounting leg;

FIGS. 6 (a), (b) and (c) are a rear view and a sectional view showing the structure of a roof rail mounting leg.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masae Kobayashi 1015 Hodosawa, Gotemba-shi, Shizuoka Japan G-Plastics Co., Ltd. Applied Technology Research Center (72) Inventor Hiroshi Yamamoto 1-7-1, Nishishinjuku, Shinjuku-ku, Tokyo No. 2 Inside Fuji Heavy Industries Ltd. (72) Inventor Shigeyuki Osawa 1-7-2 Nishi Shinjuku, Shinjuku-ku, Tokyo Inside Fuji Heavy Industries Ltd. (56) References JP-A-6-32178 (JP, A) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) B60R 9/04

Claims (5)

(57) [Claims] An installation roof leg for an automobile, wherein a resin gate is provided at one end of the installation leg, and a gas gate is provided inside a mounting seal surface. leg. 2. The material of the mounting leg is 10 ⁻⁴ (sec.).
^-1 ) The viscosity at the time of shearing is 90 to 150 Pa · sec, 1
Viscosity at the time of shearing of 0 ³ (sec ⁻¹ ) is 400 to 700P
a · sec, the viscosity at the time of shearing of 10 ² (sec ⁻¹ ) is 1
000 to 2000 Pa · sec, 10 ¹ (sec ^-1 )
The roof leg mounting portion for an automobile according to claim 1, wherein the resin is formed of a thermoplastic resin having a viscosity of 1500 to 3000 Pa-sec when sheared. 3. The method according to claim 1, wherein the thermoplastic resin is polycarbonate /
3. The mounting leg for an automobile roof rail according to claim 2, wherein the mounting leg is a polymer alloy of polybutylene terephthalate. 4. The method according to claim 1, wherein the thermoplastic resin is injected into the mold cavity from a resin gate, and after a predetermined time, an inert gas is injected under pressure from the gas gate.
Or the mounting leg part of the roof rail for motor vehicles of Claim 2. 5. The mounting leg for an automobile roof rail according to claim 1, wherein the mounting leg has a hollow portion formed by a gas assisted injection method.