JP3864961B2 - Steering wheel manufacturing method - Google Patents

Description

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

  Conventionally, for example, when a steering wheel having a structure in which a part of a ring part is wound with leather is requested from a design requirement, a hard wheel is sequentially formed around the ring core metal along the circumferential direction of the ring part. A steering wheel is manufactured by molding a plurality of covering portions made of a soft synthetic resin material and sewing leather around the soft covering portion.

  Furthermore, regarding a steering wheel configured by sequentially forming a plurality of synthetic resin coating portions along the planar circumferential direction of the ring portion, if the weight reduction is desired, the ring core metal is made of an aluminum alloy or the like. It was considered to be made of die-cast metal made of

  Further, when the ring cored bar is made of die-cast metal, the cross-sectional shape has to be U-shaped in order to have the same strength as the ring cored bar made of a conventional steel pipe (for example, a patent) Reference 1 and 2).

In addition, in order to ensure the shape and size of the coated portion after molding and to avoid troublesome post-processing, it is necessary to prevent the occurrence of burrs.
JP-A-4-325374 JP-A-8-133303

  However, in order to prevent the occurrence of burrs, the mold surface of the mold must be brought into contact with the entire circumference of the inner peripheral side and the outer peripheral side of the U-shaped cross section of the ring core metal. However, due to variations in the dimensional accuracy of the core metal itself and variations in setting to the mold, it was difficult to accurately press the mold surface all around the ring core metal.

  The present invention solves the above-described problem, and provides a method for manufacturing a steering wheel that can suppress the generation of burrs around the covering portion and can ensure high dimensional accuracy of the covering portion provided around the ring core metal. For the purpose.

The method for manufacturing a steering wheel according to the present invention includes a plurality of synthetic resin coating portions sequentially formed around a die-cast metal core bar having a U-shaped cross section in a ring portion along a plane circumferential direction of the ring portion. A method for manufacturing a steering wheel, comprising:
The covering portion formed in order along the planar circumferential direction of the ring portion in 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 covering portion that is formed after the forming of the first covering portion.
The ring cored bar of the steering wheel is cast at the end surface portion of the first covering part at the time of die casting of the ring cored bar to block the groove on the inner peripheral side of the U-shaped cross section. An occlusion part for
At the time of molding the first covering portion, the first covering portion is formed on the outer peripheral surface of the ring core metal including the outer peripheral surface of the closing portion so as to suppress generation of burrs in the molding material of the first covering portion The mold surface of the mold is brought into pressure contact, the mold is closed, the molding material of the first covering portion is injected into the molding die, and the first covering portion is molded. And

  In the method for manufacturing a steering wheel according to the present invention, the ring cored bar of the steering wheel has a burr cutting closing portion for closing a groove on the inner peripheral side of the U-shaped cross section at a portion of the end surface of the first covering portion. It is prepared for. Therefore, at the time of molding the first covering portion, with respect to the mold surface of the mold of the first covering portion, at the burr cutting portion of the first covering portion, only the outer peripheral surface of the ring core including the outer peripheral surface of the closing portion, The mold surface only needs to be pressed, and it is not necessary to press the mold surface to the inner peripheral side of the U-shaped cross section. Therefore, the generation of burrs is suppressed during molding, and the burr cutting is improved.

  Therefore, in the method for manufacturing a steering wheel according to the present invention, the first covering portion has good burr cutting, and the first covering portion provided around the ring core metal can ensure high dimensional accuracy, such as deburring. The post-processing effort 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 that is gripped at the time of steering, a boss portion B that is disposed in the center of the ring portion R, a ring portion R, and a boss. The four spoke portions S that connect the portion B, and a steering wheel metal core 1 for connecting the portions to each other is provided.

  The core metal 1 is composed of a boss core metal 2 arranged in the boss part B, a spoke metal core 3 arranged in each spoke part S, and a ring metal core 4 arranged in the ring part R. . And as for the metal core 1, the site | part of the boss | hub 2a of the center of the boss | hub part metal core 2 connected with the steering shaft of the vehicle which is not shown in figure is made of steel, the surrounding boss plate 2b, the spoke part metal core 3, and The ring cored bar 4 is formed of a die cast metal such as an aluminum alloy by die casting.

  The ring cored bar 4 has a U-shaped cross section as shown in FIG. However, in the ring cored bar 4 of the embodiment, in the vicinity of four places to be described later, the closing part 5 that closes the inner peripheral side of the U-shaped section and the inner peripheral surface side of the U-shaped section are along the circumferential direction of the cross section. Two protrusions 6 and 6 are formed (see FIGS. 2 and 3).

  In addition, as shown in FIGS. 1 to 3, the ring portion R is hard around the core metal 4 so as to be along the forming direction of the ring portion R, that is, along the plane circumferential direction of the ring portion R. A first covering portion 8 formed from a synthetic resin and a second covering portion 9 formed from a soft synthetic resin that is softer than the first covering portion 8 are disposed, and leather or the like is disposed around the second covering portion 9. The outer skin 11 made of is stitched and arranged.

  In the case of the embodiment, a total of two first covering portions 8 are disposed at the front and rear portions of the steering wheel W, and each is formed from a hard synthetic resin such as polypropylene. In addition, annular grooves 8 c into which the terminals 11 a of the outer skin 11 are fitted are formed at the end portions 8 a of the first covering portions 8.

  The 2nd coating | coated part 9 is shape | molded after shaping | molding of the 1st coating | coated part 8, is arrange | positioned in the site | part on either side of the steering wheel W, and is formed from foaming urethane etc., respectively.

  The outer skin 11 is arranged with the terminal 11a fitted into the annular groove 8c while the vicinity of the terminal 11a is brought into direct contact with the outer peripheral surface of the end portion 8a of the first covering portion 8. The leathers 11 and 11 are sewn on the inner side of the ring part R on the boss part B side.

  Then, a burr cutting closing portion 5 for closing the groove 4a on the inner peripheral side of the U-shaped cross section is formed in the portion of the ring core metal 4 located on each end face 8b of the first covering portion 8 or 8. ing. In addition, the ring cored bar 4 located so as to be embedded in the end 8a of the first covering portion 8 has two protrusions 6 along the circumferential direction on the inner peripheral surface side of the groove 4a. 6 is formed.

  When manufacturing the steering wheel W of the embodiment is described, the steering wheel core 1 is manufactured in advance. The steering wheel mandrel 1 is manufactured by setting a boss 2a in a predetermined die-casting die and die-casting including the closed portion 5 and the convex portions 6 and 6.

  Then, the steering wheel metal core 1 is set on a molding die 20 (see FIGS. 5 and 6) that is composed of the split molds 21 and 22 and can mold the first covering portion 8 in the mold open state. The molding material for the covering portion 8 is injected, and the first covering portions 8 and 8 having the annular groove 8c are injection-molded.

  Next, the steering wheel core 1 provided with the first covering portions 8 and 8 is set on the forming die of the second covering portion 9 after being released from the mold 20 that has been opened, and after the mold is clamped, the second covering is performed. The molding material for the portion 9 is injected to mold the second covering portions 9 and 9. The mold surface of the molding die of the second covering portion 9 is brought into a state where the outer peripheral surface of each end portion 8a of the first covering portion 8 is in pressure contact with the mold clamping.

  Thereafter, the second covering portion 9 is released from the molding die, and the outer skin 11 is sewn around the second covering portions 9 and 9. At that time, the terminal 11 a is fitted into the annular groove 8 c provided in the first covering portion 8 while the vicinity of the end 11 a of the outer skin 11 is brought into direct contact with the outer peripheral surface of the end portion 8 a of the first covering portion 8. To arrange. The outer skin 11 may be adhered to the outer peripheral surface of the end portion 8a by applying an adhesive as desired.

  Furthermore, if a lower cover or a pad P (not shown) is attached to the lower part or the upper part of the boss part B, the manufacture of the steering wheel W is completed, and it can be used by being mounted on the vehicle. Since the steering wheel W is nut-fastened to the steering shaft when mounted on the vehicle, the pad P 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 according to such an embodiment, the ring core metal 4 closes the groove 4a on the inner peripheral side of the U-shaped cross section at each end face 8b in the first covering portions 8 and 8. It is configured to include a closing part 5 for burr cutting. Therefore, with respect to the mold surfaces 21a and 22a of the mold 20 of the first covering portion 8 and 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. It is sufficient that the mold surfaces 21a and 22a are pressed against only the outer peripheral surface of the ring cored bar 4, and it is not necessary to press the mold surface against the inner peripheral side of the U-shaped cross section. It is suppressed and the burr cutting becomes good.

  Therefore, in the method for manufacturing the steering wheel W according to the embodiment, the first covering portion 8 has good burr cutting, and the first covering portions 8 and 8 provided around the ring core 4 can ensure high dimensional accuracy. In addition, it is possible to reduce the trouble of post-processing such as deburring.

  In the steering wheel according to the embodiment, the ring cored bar 4 includes the convex portions 6 and 6 at the positions where the end portions 8a of the first covering portions 8 and 8 are arranged. When the part 8 is molded, it is caught by the convex parts 6 and 6, and molding shrinkage of the first covering parts 8 and 8 is suppressed.

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

  In addition, in embodiment, in order to prevent the shaping | molding shrinkage | contraction of 1st coating | cover part 8 * 8, the case where the two convex parts 6 provided in the ring part metal core 4 were provided in the inner peripheral surface side of the groove | channel 4a was shown. However, one or three or more may be provided, and further, a protruding portion that is partially protruding may be used instead of the protruding row. Furthermore, as shown in FIG. 7, the convex portion 6 may be provided on the outer peripheral surface side of the ring core metal 4. By the way, when the convex portion 6 is provided on the outer peripheral surface side of the ring core metal 4, the first covering portions 8 and 8 are easily caught compared to the case where the convex portion 6 is provided on the inner peripheral surface side of the groove 4 a. Can be lowered.

  Moreover, although the case where the outer surface of the 1st coating | coated part 8 was made into a pattern was shown in embodiment, after the shaping | molding of the 2nd coating | coated part 9, etc., hydraulic transfer is carried out to the outer surface of the 1st coating | coated part 8 * 8. The decorative layer may be provided by painting such as.

  Further, in the embodiment, the case where two types of the covering portions 8 and 9 covering the ring core metal 4 are shown, but three or more types of covering portions may be provided, and in this case, burr cutting is required. The covering portion 5 is provided with the closing portion 5 at the site of the covering portion, and the convex portion 6 is provided so as to be embedded in the end portion of the covering portion to prevent molding shrinkage, thereby ensuring high dimensional accuracy of these covering portions. Just do it.

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

Explanation of symbols

4 ... Ring cored bar,
4a ... groove,
5 ... Blocking part,
6 ... convex part,
8 (first) covering part,
8a ... the 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 in which a plurality of synthetic resin covering portions are sequentially formed around a die metal core made of a U-shaped cross section in a ring portion along a plane circumferential direction of the ring portion,
The covering portion formed in order along the planar circumferential direction of the ring portion in 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 covering portion that is formed after the forming of the first covering portion.
The ring cored bar of the steering wheel is cast at the end surface portion of the first covering part at the time of die casting of the ring cored bar to block the groove on the inner peripheral side of the U-shaped cross section. An occlusion part for
At the time of molding the first covering portion, the first covering portion is formed on the outer peripheral surface of the ring core metal including the outer peripheral surface of the closing portion so as to suppress generation of burrs in the molding material of the first covering portion The mold surface of the mold is brought into pressure contact, the mold is closed, the molding material of the first covering portion is injected into the molding die, and the first covering portion is molded. A method for manufacturing a steering wheel.

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