JPH0139892B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a urethane product in which a coating layer made of a urethane foam material is formed on the outer periphery of a core metal of a ring portion, and irregularities are formed on the back side of the ring portion of the coating layer. This invention relates to a method for manufacturing a steering wheel.

(Prior art) Conventionally, a coating layer 2b made of a urethane foam material is formed on the outer periphery of a ring core bar 2a as shown in FIG.
B has unevenness 2c for reasons such as ease of grip and non-slip.
(See FIG. 9) There is a urethane steering wheel 1 formed thereon. The manufacturing process involves placing the steering wheel core metal to which the ring part core metal 2a, the spoke part core metal 3a, the boss plate 4, and the boss 5 are connected, into an upper and lower mold 6a so that the back side of the steering wheel is placed at the top during molding. 6b
After closing the mold, urethane foam material is injected into the cavity 7 from a film gate 8 of uniform height h located on the outer periphery of the ring part 2 to be molded, and then injection molding (reaction injection molding) is performed. A covering layer 2b was formed. In addition, in this steering wheel 1, the core metal 3 is also used in the spoke portions 3.
When the coating layer 2b of the ring portion 2 is formed, a coating layer 3b made of a urethane foam material is simultaneously formed on the outer periphery of the ring portion a.

In manufacturing this urethane steering wheel 1, the coating layer 2b is formed from a urethane foam material, so when the coating layer 2b is molded, air inside the cavity 7 and bubbles of the foaming agent itself may cause the inside of the cavity 7 to Air tends to accumulate in the ring part 2, and if molded with air accumulated, the ring part 2
Since a cavity is formed on the outer periphery, air vent holes 9, 10 are provided in the uneven portion 6a0 near the gate 8 of the upper mold 6a of the mold 6 where air tends to accumulate, and at symmetrical positions of the gate 8. It was necessary to blow out the molding material together with air (see Figures 8, 9, and 10).

However, when the air bleed holes 9 and 10 are provided in this way, the amount of molding material blown out from the air bleed holes 9 and 10 may be approximately equal to the amount of the coating layer 2b of the steering wheel 1 to be molded. , the yield was poor.

When molding the coating layer 2b, the reason why the steering wheel core metal is set in the mold 6 so that the back side of the steering wheel is placed at the top during molding is that the processing traces of the material that has entered the air vent holes 9 and 10 are removed from the steering wheel. This is to prevent it from coming out to the surface side of the wheel 1.

(Purpose of the Invention) The present invention provides that, in the manufacture of this type of urethane steering wheel, the air vent hole in the upper mold of the mold used during molding can be formed only in the symmetrical position of the gate, and the air vent hole in the upper mold can be formed only in the symmetrical position of the gate. An object of the present invention is to provide a method for manufacturing a urethane steering wheel, which can eliminate the need for urethane foam material and improve the yield of urethane foam material, which is a molding material, when forming a coating layer around the outer periphery of a ring part.

(Structure of the Invention) The gist of the present invention is to inject a urethane foam material into a cavity through a film gate, form a coating layer on the outer periphery of a ring core placed in the cavity, and include a coating layer on the back surface of the ring portion. A method for manufacturing a urethane steering wheel in which unevenness is formed on the side portions, characterized in that the heights of both side portions and the center portion of the steering wheel are made different at or near the opening on the cavity side of the gate. There is a method for manufacturing a urethane steering wheel.

(Example) FIG. 1 is a sectional view of the gate opening during molding in the first embodiment of the present invention, and FIG.
A cross-sectional view of the gate opening in the linear direction, FIG. 3 is a back view of the steering wheel manufactured in the same example,
FIG. 4 is a sectional view of the gate opening during molding in the second embodiment, FIG. 5 is a sectional view of the gate opening in the - line direction of FIG. 4, and FIG. 6 is a sectional view of the gate opening during molding in the third embodiment. FIG. 7 is a sectional view of the gate opening and a partial plan view of the lower die used in the same embodiment.

The urethane steering wheel 11 manufactured according to the first embodiment has coating layers 12b and 13b made of urethane foam material formed on the outer periphery of the ring part core metal 12a and the spoke part core metal 13a, which are similar to the conventional ones. The coating layer 12b on the back side is provided with irregularities 12c for reasons such as ease of grip and anti-slip properties.

The mold 16 used in the first embodiment is the same as the conventional urethane steering wheel 1.
Upper mold 16 equipped with a cavity 17 corresponding to 1
a and a lower mold 16b, and is equipped with a film gate 18 for injecting the urethane foam material into the cavity 17, and the upper mold 16a has air bleed holes 20 only at symmetrical positions of the gate 18 (see Fig. 3).
is formed.

The opening 18a of the film gate 18 on the cavity 17 side in the mold 16 is formed such that the height h1a at both sides is higher than the height h1b at the center. In the embodiment, the width w1 of the opening 18a is 58 mm, the height h1a at both sides is 1.2 mm, and the height h1b at the center is 0.8 mm.

To describe the manufacture of the urethane steering wheel 11 using this mold 16, first,
The steering wheel core metal to which the ring part core metal 12a, the spoke part core metal 13a, the boss plate 14, and the boss 15 are connected is placed in a predetermined position in the upper mold 16a so that the back side of the steering wheel (ring part 12) is placed at the top during molding. position.

Then, the mold is closed, and urethane foam material is injected into the cavity 17 through the gate 18 to form coating layers 12b and 13b on the outer peripheries of the ring part core metal 12a and the spoke part core metal 13a. At that time, in the opening 18a of the gate 18 on the side of the cavity 17, the height h1a of both sides and the height h1 of the center part are
b are different, and the molding material is injected into the cavity 17 at different flow velocities between both sides and the center of the gate opening 18a, so that the uneven portion 16a of the upper die 16, where it has conventionally been easy to accumulate, is injected into the cavity 17. The air is swept away by the molding material, and even if an air vent hole is not formed in this region, molding can be performed without creating a cavity on the outer periphery of the ring portion 12.

Incidentally, the difference between the height h1a on both sides of the gate opening 18a and the height h1b at the center is 0.2 when the width w1 of the opening 18 is 50 mm to 65 mm.
A similar effect was obtained when the thickness was mm to 0.8 mm.

After that, open the mold, and after releasing the mold, open the air vent hole 2.
A urethane steering wheel 11 can be obtained by post-processing the portion 0.

Therefore, in the first embodiment, molding can be performed without providing a conventional air vent hole in the upper die 16a near the gate 18;
The amount of molding material blown out from the air vent hole 20 is approximately half of the total amount of the conventional method, improving the yield.
Post-processing is also easier because only one air vent hole is required compared to the conventional two.

In the first embodiment, a mold 16 is used in which the height h1a of both sides of the gate opening 18a is higher than the height h1b of the center part, but the second embodiment shown in FIGS. The mold 26 used in the embodiment may also be used.

This mold 26 is the mold 1 used in the first embodiment.
The film gate 28, which is composed of an upper mold 26a and a lower mold 26b similar to 6, and which injects the urethane foam material into the cavity 27, has an opening 28a on the cavity 27 side that is higher than the height h2a of the both sides. The height h2b is increased.
In the example, the width w2 of the opening 28a is 58 mm, the height h2a at both sides is 1.2 mm, and the height h2b at the center is 1.6 mm.
mm.

When manufacturing a urethane steering wheel using this mold 26, as in the first embodiment, the molding material flows through the cavity 2 with different flow velocities between both sides and the center of the gate opening.
7, the gate 28 of the upper mold 26a
The covering layer 22b of the ring portion can be molded without a cavity without providing an air bleed hole in the vicinity, the yield of molding material can be improved, and post-processing of the air bleed hole can be facilitated.

Furthermore, in the opening on the cavity side of the film gate, it is sufficient to make the flow velocity of the molding material different between the both sides and the center, so as shown in the third embodiment shown in FIGS. Ya upper mold 36
The ratio of the width w3 of the film gate opening 38a to the center of the film gate opening 38a near the cavity 37 side in a is set to 10:5 to 10:5.
With a width a of 10:8, the film gate opening 38
The same effect as in the first and second embodiments can be obtained even if the protrusion 40 is provided with a height such that the ratio of a to the height h3 is 10:2 to 10:8, and the mold 36 is used for molding. play.

In addition, in the example, a coating layer made of urethane foam material is also formed on the outer periphery of the core metal of the spoke part, but of course, even if the coating layer is formed only on the outer periphery of the core metal of the ring part, the same method can be applied. be effective.

(Effects of the Invention) The method for manufacturing a urethane steering wheel according to the present invention provides a method of manufacturing a urethane steering wheel using a mold in which the heights of both sides and the center of the film gate of the mold used at the cavity side opening or the vicinity thereof are different. During molding, the molding material is injected into the cavity at different flow velocities between the sides of the gate opening and the center. The air in this area can be swept away, molding can be performed without forming an air vent hole in this area, the yield of molding material can be improved, and post-processing of the molded product using air vent holes in this area can be eliminated. play.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the gate opening during molding in the first embodiment of the present invention, and FIG. 2 is the same as that shown in FIG.
A cross-sectional view of the gate opening in the linear direction, FIG. 3 is a back view of the steering wheel manufactured in the same example,
FIG. 4 is a sectional view of the gate opening during molding in the second embodiment, FIG. 5 is a sectional view of the gate opening in the - line direction of FIG. 4, and FIG. 6 is a sectional view of the gate opening during molding in the third embodiment. A sectional view of the gate opening, FIG. 7 is a partial plan view of the lower mold used in the same example, FIG. 8 is a back view of the steering wheel manufactured by the conventional method, and FIG. 9 is the gate during conventional molding. 10 is a sectional view of the gate opening in the direction of the - line in FIG. 9. 1, 11... Urethane steering wheel, 2, 12... Ring portion, 2a, 12a... Ring portion core metal, 2b, 12b... Covering layer, 6, 1
6, 26, 36...Mold, 6a, 16a, 26
a, 36a...upper mold, 6b, 16b, 26b, 3
6b... lower mold, 7, 17, 27, 37... cavity, 8, 18, 28, 38... film gate, 18a, 28a, 38a... opening.

Claims (1)

[Claims] 1. A urethane foam material is injected into the cavity through the film gate to form a coating layer around the outer periphery of the ring part core metal disposed in the cavity, and the coating layer has irregularities formed on the back side of the ring part. A method for manufacturing a urethane steering wheel, characterized in that the opening on the cavity side of the gate or its vicinity is formed with different heights between both sides and the center. manufacturing method.