JPS5945275A - Manufacture of steering wheel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for steering a steering wheel used in a steering device such as an automobile.

The ring '4ki- of the steering wheel is the outer part of the core metal formed in an annular shape! This type of tl has an exterior made of synthetic resin, and some use foamed synthetic resin such as polyurethane foam or polyvinyl chloride polyohm as the base side of the exterior. This type of exterior material is made by injecting a foaming solution into a mold with a core metal housed in it and foaming it into a predetermined shape. Therefore, it is preferable to position the gas venting port at the outermost part of the mold, and to position the stock solution injection port at the bottom of the mold, facing the gas venting port. There was a drawback that the density and hardness of the foam tended to differ between the vicinity of the gas vent and the vicinity of the liquid inlet. In other words, the foam tends to have a high density and high hardness near the stock solution injection port, and the cause of this is, for example, that gas generated by foaming is flowed toward the gas vent, creating bubbles near the stock solution injection port. This is thought to be due to the fact that when the foaming rate is insufficient or the foaming rate is low, the foaming reaction starts before the contained gas is sufficiently exhausted from the gas venting port, resulting in variations in the foaming degree.

However, if there is a difference in the density or hardness of the foam as described above, there is a drawback that the feel of the grip varies depending on the position in which the ring portion is gripped, especially with respect to the hardness, resulting in a feeling of discomfort.

The present invention has been made based on the above circumstances, and its purpose is to reduce variations in density and hardness that occur near the stock solution injection port and near the degassing day,
It is an object of the present invention to provide a method for manufacturing a steering wheel that can form a homogeneous foam over the entire circumference of a ring part.

That is, in the present invention, a mold is installed so that the raw foil injection port is located at the bottom and the small gas vents are located at the top, and within this mold, the cross section of the portion located at the gas vents is Manufacture of a steering wheel characterized by housing a ring part core bar shaped so that the cross-sectional area gradually decreases toward the stock solution injection port, and injecting a foaming stock solution from the stock solution injection port to perform foam molding. It's a method.

An embodiment of the method of the present invention will be described below with reference to all the drawings. FIG. 1 shows an example of a ring portion core metal 1 of a steering wheel used in the method of the present invention. That is, as shown in Fig. 2, the ring core metal 1 is bent and formed into a ring-shaped metal rod or metal tube, so that the center part is thin and the thickness gradually increases toward both ends. At the same time, the two end faces 1 a + J a k are butted against each other and connected by appropriate joining means such as welding, adhesion, fitting, caulking, etc., thereby forming a ring as shown in FIG. 1. Therefore, the cross-sectional area of the core bar 1 is such that the section located at the bottom +111 in the drawing is the thinnest and the section located at the top in the drawing gradually becomes thicker.

As shown in FIG. 3, a core metal 1 having a shape in which the central portion is thick and the thickness of both IM portions t111 gradually decreases is bent into an annular shape in the same manner as described above, and both ends 1a of the core bar 1 are formed.

laf bonding to form a ring similar to that shown in FIG.

Then, the ring portion core metal 1 is housed in a mold 2 for foam molding. In this mold 2, a molding groove 2a having the same inner diameter is formed around the entire circumference according to the shape of the foam to be molded, and a stock solution injection port 3 communicating with this molding groove 2a and a gas An extraction port 4 is provided.

The mold 2 is installed such that the stock solution inlet 3 is located at the bottom and the gas vent 4 is located at the top.

As shown in FIG. 4, the core bar 1 has a portion 1b with the largest cross-sectional area located near the gas vent 4, and a portion 1c with a smaller cross-sectional area located at the stock solution injection port 3.
It is housed so that it is located on the side. Therefore, in this state,
The gap between the core metal 1 and the molding 6''r; 2a becomes maximum near the stock solution injection port 3, and gradually narrows toward the gas vent 4 side.

After the core metal 1 is set in the mold 2 in this way, the stock solution of soft T synthetic resin foam such as polyurethane, polyvinyl chloride, polyethylene, etc. is injected into the stock solution injection port 3. The gas in the molding groove 2a is gradually filled, and the gas in the molding groove 2a is discharged from the gas vent 4.

After foaming, the desired synthetic resin foam 5 is obtained by curing. Note that the foaming and assimilation time of the foam stock solution depends on the temperature of mold 2, the insert temperature of the stock solution, elapsed time, catalyst, etc.

In the steering wheel obtained as described above, since the outer diameter of the foam 5 (the outer diameter of the cross section) is the same over the entire circumference of the ring, the outer diameter of the foam 5 in the vicinity of the gas vent 4 is
In other words, as shown in the figure, in the state before foaming, the thin part of the core metal is Forming groove 2a near fυ stock solution injection port 3
In addition, the thick part of the core metal 1 freezes and the space becomes narrow near the gas vent port 4+J, so foaming is suppressed and the density increases near the gas vent port 4, where the space is narrow. , and the hardness can be increased so that gas accumulation, which is seen in conventional products, is less likely to occur. On the other hand, the foaming rate increases near the stock solution injection port 3, which has a wide space, and the area that was too hard in the conventional product becomes soft. Therefore, the relative difference in density and hardness that occurs near the stock solution injection port and the gas vent port is reduced, which is extremely effective in making the grip feel uniform.

Moreover, the gap between the core metal 1 and the forming groove 2a has a flow passage cross-sectional area such that the lower side is wide and the upper part, that is, the gap 4 (III) gradually narrows, so that the gas flow rate increases. Gas venting efficiency station: Direction:

The shape of the core metal can be circular, rectangular, rectangular, polygonal, or any other shape. It is sufficient that the core bar is large and that the cross-sectional area gradually decreases toward the part located on the side where the stock solution is injected.Furthermore, the core bar may be either solid or hollow.

As described above, the present invention uses a core metal whose cross section f and '1 change, and the cross-sectional area of the core metal is small near the stock solution inlet, and the cross-sectional area of the core metal is small near the bank. The foaming solution is injected by placing the foaming solution inside the core metal mold to increase the size of the foam, which increases the degree of foaming and reduces the hardness near the solution injection port, where conventional foams tend to become hard and break. In addition, it is possible to increase the hardness by suppressing foaming in the vicinity of the gas vent, where hardness has conventionally been apt to be insufficient, and it is possible to reduce the occurrence of differences in density and hardness between these two parts. Therefore, a homogeneous foam can be obtained over the entire circumference of the ring portion, which is highly effective in eliminating the strange feeling in the grip and improving quality.

[Brief explanation of drawings]

Fig. 1 is a plan view of the ring portion core metal used in the method of the present invention, Fig. 2 is a perspective view of the core metal before bending, Fig. 3 is a perspective view showing a modified example of the core metal, and Fig. 4 is a perspective view of the core metal before bending. 5 is a cross-sectional view of the core metal covered with foam, and FIG. 5 is a cross-sectional view taken along the line ■-v in FIG.
The figure is a cross-sectional view taken along the line ■-■ in FIG. 4. DESCRIPTION OF SYMBOLS 1... Ring part core metal, 2... Mold, 3... Stock solution injection port, 4... Gas venting port, 5... Foam. Applicant's Representative Patent Attorney Takehiko Suzue Figure 1 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] A mold is installed so that the stock solution injection port is located at the bottom and the gas vent port is located at the top. A method for manufacturing a steering wheel, characterized in that a ring part core metal having a shape in which the ribs decrease in shape toward the direction of the steering wheel is housed, and a foaming stock solution is injected from the stock solution injection port to perform foam molding.