JP2004210292A - Method for manufacturing steering wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a steering wheel for ensuring high dimensional precision by a covered part provided around a ring part core metal unit by suppressing the occurrence of burr around the covered part. <P>SOLUTION: In this method for manufacturing the steering wheel for forming a plurality of covered parts made of synthetic resin sequentially along the peripheral direction of a plane in a ring part around the core metal unit 4 made of die-cast metal and having U-shaped cross section of the ring part, the covered part is provided with a first covered part 8 formed by hard synthetic resin and a second covered part formed by soft synthetic resin and molded after molding the first covered part. The ring part core metal unit is provided with a blocking part 5 for cutting burr which is cast when performing die casting of the ring part core metal unit and blocks a channel 4a on an inner peripheral side of the U-shaped cross section in a section on an end face of the first covered part. The first covered part 8 is molded by bringing mold faces 21a, 22a of a mold 20 in the first covered part into pressure contact with an outer peripheral face of the ring part core metal unit 4 including an outer peripheral face of the blocking part 5 to close the mold and pouring a molding material. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a steering wheel for steering a vehicle. The present invention relates to a method of manufacturing a steering wheel configured by forming a plurality of synthetic resin covering portions in order along a forming direction of a ring portion, that is, along a plane circumferential direction of the ring portion.

  Conventionally, from a design requirement, for example, when a steering wheel having a configuration in which a part of a ring portion is wound with leather is required, a hard wheel is sequentially formed around a ring core metal along the plane circumferential direction of the ring portion. A plurality of covering portions made of soft synthetic resin material are formed, and leather is sewn around the soft covering portion to manufacture a steering wheel.

  Further, regarding a steering wheel configured by forming a plurality of synthetic resin covering portions in order along the plane circumferential direction of such a ring portion, if a reduction in weight is desired, the ring core metal is made of aluminum alloy or the like. It was considered to be made of die-cast metal.

  Further, when the ring core is made of die-cast metal, it is necessary to make the cross-sectional shape U-shaped in order to make the strength equal to that of the conventional ring core made of steel pipe (for example, see Patent References 1 and 2).

Further, in order to secure the shape and dimensions of the coated portion after molding and to avoid trouble in post-processing, it has been necessary to prevent generation of burrs.
JP-A-4-325374 JP-A-8-133093

  However, in order to prevent the occurrence of burrs, it has been necessary to accurately bring the mold surface of the mold into contact with the entire inner circumference and outer circumference of the U-shaped cross section of the ring core. However, due to variations in the dimensional accuracy of the core metal itself and variations in setting in a molding die, it was difficult to accurately press the mold surface over the entire circumference of the ring core metal.

  The present invention has been made to solve the above-described problem, and provides a method of manufacturing a steering wheel capable of suppressing occurrence of burrs around a coating portion and ensuring high dimensional accuracy of a coating portion provided around a ring core. The purpose is to:

In the method for manufacturing a steering wheel according to the present invention, a plurality of synthetic resin covering portions are sequentially formed around a die-cast metal core having a U-shaped cross section in a ring portion along a plane circumferential direction of the ring portion. A method of manufacturing a steering wheel,
The covering portion formed sequentially along the plane circumferential direction of the ring portion of the steering wheel is formed of a first covering portion formed of a hard synthetic resin and a soft synthetic resin softer than the first covering portion. And a second coating portion formed after the first coating portion is formed.
The ring core of the steering wheel is cast at an end surface portion of the first coating portion at the time of die casting of the ring core, and a burr cut for closing a groove on an inner peripheral side of a U-shaped cross section. A closing part for
At the time of molding the first covering portion, the first covering portion is provided on the outer peripheral surface of the ring core metal including the outer peripheral surface of the closing portion so that generation of burrs of the molding material of the first covering portion can be suppressed. The mold surface of the mold is pressed against the mold, the mold is closed, the molding material of the first covering portion is injected into the mold, and the first covering portion is molded and manufactured. And

  In the manufacturing method of the steering wheel according to the present invention, the ring core metal of the steering wheel has, at the end face portion of the first coating portion, a closing portion for burr cutting for closing an inner circumferential groove of a U-shaped cross section. It is provided with. Therefore, at the time of molding the first coating portion, with respect to the mold surface of the molding die of the first coating portion, at the burr cutting portion of the first coating portion, only the outer peripheral surface of the ring core including the outer peripheral surface of the closing portion is provided. It is sufficient that the mold surface is pressed, and the mold surface does not need to be pressed against the inner peripheral side of the U-shaped cross section. Therefore, at the time of molding, the occurrence of burrs is suppressed, and burr cutting is improved.

  Therefore, in the method of manufacturing a steering wheel according to the present invention, the first coating portion has good deburring, and the first coating portion provided around the ring core can secure high dimensional accuracy, and can be used for deburring and the like. Post-processing can be reduced.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 to 3, the steering wheel W manufactured in the embodiment includes an annular ring portion R gripped during steering, a boss portion B disposed at the center of the ring portion R, a ring portion R, and a boss. And four spokes S connecting the parts B, and each part is provided with a steering wheel core 1 for connecting the parts.

  The core metal 1 is composed of a boss core metal 2 disposed on the boss B, a spoke core metal 3 disposed on each spoke S, and a ring core metal 4 disposed on the ring R. . The core 1 has a boss 2a at the center of the boss core 2 connected to a steering shaft of a vehicle (not shown) made of steel, and has a boss plate 2b, a spoke core 3, and a surrounding boss plate 2b. The ring core 4 is formed of a die-cast metal such as an aluminum alloy by die-casting.

  The ring core 4 has a U-shaped cross section as shown in FIG. However, in the ring core metal 4 of the embodiment, a blocking portion 5 that closes the inner peripheral side of the U-shaped cross section and the inner peripheral surface side of the U-shaped cross section along the cross-sectional circumferential direction are provided near four locations described later. Two convex portions 6.6 are formed (see FIGS. 2 and 3).

  As shown in FIGS. 1 to 3, the ring portion R is hardened around the cored bar 4 along the direction in which the ring portion R is formed, that is, along the plane circumferential direction of the ring portion R. A first covering portion 8 made of a synthetic resin and a second covering portion 9 made of a soft synthetic resin softer than the first covering portion 8 are arranged, and leather or the like is provided around the second covering portion 9. The outer skin 11 is stitched and arranged.

  In the case of the embodiment, a total of two first covering portions 8 are arranged at the front and rear portions of the steering wheel W, each of which is formed of a hard synthetic resin such as polypropylene. Further, an annular groove 8c for fitting the terminal 11a of the outer cover 11 is formed in the end 8a of each first covering portion 8 respectively.

  The second covering portion 9 is formed after the formation of the first covering portion 8, is disposed on the left and right portions of the steering wheel W, and is formed of urethane foam or the like.

  The outer cover 11 is arranged by fitting the terminal 11a into the annular groove 8c while directly contacting the vicinity of the terminal 11a with the outer peripheral surface of the end 8a of the first covering portion 8. The leathers 11 are sewn on the inside of the ring R on the boss B side.

  At the portion of the ring core 4 located on each end face 8b of the first covering portion 8, a burr-cutting closing portion 5 for closing the groove 4a on the inner peripheral side of the U-shaped cross section is formed. ing. In addition, at the portion of the ring core 4 located so as to be buried in the end 8a of the first covering portion 8, two convex portions 6 along the cross-sectional circumferential direction are provided on the inner peripheral surface side of the groove 4a. 6 are formed.

  The manufacturing of the steering wheel W according to the embodiment will be described. The steering wheel core 1 is manufactured in advance. The manufacturing of the steering wheel core 1 is performed by setting the boss 2a in a predetermined die casting mold, and performing die casting including the closed portion 5 and the convex portions 6.

  Then, the steering wheel core 1 is set on the forming die 20 (see FIGS. 5 and 6), which is formed of the split dies 21 and 22 and is capable of forming the first covering portion 8 in the open state. The molding material of the covering portion 8 is injected, and the first covering portion 8.8 having the annular groove 8c is injection-molded.

  Then, the steering wheel core 1 provided with the first coating portions 8.8 is set on the forming die of the second coating portion 9 by releasing from the opened die 20 and after clamping, the second coating is performed. The molding material of the part 9 is injected to form the second covering parts 9.9. The mold surface of the molding die of the second covering portion 9 is brought into a state of pressing the outer peripheral surfaces of the respective end portions 8a of the first covering portion 8 at the time of clamping.

  After that, the mold is released from the mold of the second covering portion 9, and the outer skin 11 is stitched and arranged around the second covering portion 9. At this time, the terminal 11a is fitted into the annular groove 8c provided in the first coating portion 8 while the vicinity of the terminal 11a of the outer cover 11 is brought into direct contact with the outer peripheral surface of the end 8a of the first coating portion 8. And place it. The outer skin 11 may be adhered to the outer peripheral surface of the end 8a by applying an adhesive if desired.

  Further, if a lower cover or a pad P (not shown) is attached to the lower or upper part of the boss B, the manufacture of the steering wheel W is completed, and the steering wheel W can be mounted on a vehicle and used. When the vehicle is mounted on the vehicle, the steering wheel W is fixed to the steering shaft with a nut. Therefore, the vehicle is mounted on the vehicle with the pad P removed, and the pad P is assembled after mounting.

  In the manufacturing method of the steering wheel W of such an embodiment, the ring core 4 closes the groove 4a on the inner peripheral side of the U-shaped cross section at the position of each end face 8b in the first covering portion 8.8. It is provided with a closing portion 5 for deburring. Therefore, with respect to the mold surfaces 21 a and 22 a of the molding die 20 of the first covering portion 8, the burr cutting portion C of the first covering portion 8 includes the outer peripheral surface of the closing portion 5 as shown in FIGS. The mold surfaces 21a and 22a need only be pressed against the outer peripheral surface of the outer ring core 4, and the mold surface does not have to be pressed against the inner peripheral side of the U-shaped cross section. It is suppressed and burr cutting becomes good.

  Therefore, in the method of manufacturing the steering wheel W according to the embodiment, the burr cutting of the first coating portion 8 is improved, and the first coating portion 8.8 provided around the ring core 4 can ensure high dimensional accuracy. In addition, the labor for post-processing such as deburring can be reduced.

  Further, in the steering wheel of the embodiment, since the ring core 4 is provided with the protrusions 6 at the positions of the end portions 8a in the first coating portions 8.8, the first coating is provided. When the part 8 is formed, the first covering part 8.8 is restrained from forming shrinkage by being caught by the convex part 6.6.

  Therefore, in the steering wheel W of the embodiment, the molding shrinkage of the first coating portions 8 can be suppressed, and the first coating portions 8 provided around the ring core 4 ensure high dimensional accuracy. be able to.

  In addition, in the embodiment, in order to prevent the molding shrinkage of the first coating portions 8, the case where two protrusions 6 provided on the ring core 4 are provided on the inner peripheral surface side of the groove 4 a is shown. However, one or three or more protrusions may be provided, and not a protrusion but a partially protruding protrusion may be used. Furthermore, as shown in FIG. 7, the convex portion 6 may be provided on the outer peripheral surface side of the ring core 4. Incidentally, in the case where the convex portion 6 is provided on the outer peripheral surface side of the ring core 4, the first covering portions 8 are more easily caught than in the case where the convex portion 6 is provided on the inner peripheral surface side of the groove 4 a. Can be reduced.

  Further, in the embodiment, the case where the outer surface of the first covering portion 8 is made unpatterned is shown. However, after the molding of the second covering portion 9 or the like, the outer surface of the first covering portion 8 is hydraulically transferred. The decorative layer may be provided by such painting.

  Further, in the embodiment, the case where two types of the coating portions 8 and 9 for coating the ring core 4 are shown, but three or more types of the coating portions may be provided, and in that case, burr cutting is required. A closed portion 5 is provided at the end face of the covering portion, and a convex portion 6 is provided so as to be buried in the end portion of the covering portion for preventing molding shrinkage, thereby ensuring high dimensional accuracy of the covering portion. Just do it.

It is a top view of a steering wheel showing one embodiment in the present invention. It is sectional drawing of the II-II part of FIG. It is a top view showing the state after shaping of the 1st covering part of the embodiment. It is the principal part expansion perspective view seen from the bottom face side of the ring core of the same embodiment. It is sectional drawing of the burr cutting part which shows the time of shaping | molding of the 1st coating part of the embodiment, and is sectional drawing along the cross-sectional circumferential direction of the ring core. It is sectional drawing of the burr cutting part which shows the time of shaping | molding of the 1st coating part of the embodiment, and is sectional drawing along the plane circumferential direction of the ring core. It is a partial expanded sectional view showing other embodiments.

Explanation of reference numerals

4: Ring core metal
4a ... groove,
5 ... closed part,
6 ... convex part,
8 (first) covering part,
8a ... end,
8b ... end face,
9 (second) covering part,
20: Mold,
21a, 22a: mold surface,
W: Steering wheel,
R: Ring part.

Claims (1)

A method of manufacturing a steering wheel, wherein a plurality of synthetic resin covering portions are sequentially formed around a die-cast metal core having a U-shaped cross section in a ring portion along a plane circumferential direction of the ring portion,
The covering portion formed sequentially along the plane circumferential direction of the ring portion of the steering wheel is formed of a first covering portion formed of a hard synthetic resin and a soft synthetic resin softer than the first covering portion. And a second coating portion formed after the first coating portion is formed,
The ring core of the steering wheel is cast at an end surface portion of the first coating portion at the time of die casting of the ring core, and a burr cut for closing a groove on an inner peripheral side of a U-shaped cross section. And a closing part for
At the time of molding the first covering portion, the first covering portion is provided on the outer peripheral surface of the ring core metal including the outer peripheral surface of the closing portion so that generation of burrs of the molding material of the first covering portion can be suppressed. The mold surface of the mold is pressed against the mold, the mold is closed, the molding material of the first covering portion is injected into the mold, and the first covering portion is molded and manufactured. Manufacturing method of a steering wheel.

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