JPH0510265B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a method of manufacturing a steering wheel for an automobile, etc., and particularly relates to a method of manufacturing a steering wheel for an automobile, etc. The present invention relates to a manufacturing method comprising an upper boss member and a lower boss member, and in which a spoke core metal is fixed between the upper boss member and the lower boss member by electric resistance welding.

(Prior Art) Conventionally, as a steering wheel for an automobile, etc., one described in, for example, Japanese Unexamined Utility Model Publication No. 56-59473 is known.

This steering wheel consists of upper and lower boss members that are divided into upper and lower parts in the axial direction, and spokes are inserted into the recesses formed between the upper and lower boss members, and the upper and lower boss members are connected using multiple screws. The spokes are fixed by tightening.

(Problems to be Solved by the Invention) However, the spokes disclosed in the above publication tend to rattle against the boss, and furthermore, the upper and lower boss members constituting the boss are fixed with a plurality of screws. Because of this, the formation of screw holes and screwing operations are troublesome, and many parts are required, making manufacturing troublesome.

Therefore, it is conceivable to integrally fix the spokes between the upper and lower boss members by electric resistance welding, but since the contact area between each boss member and the spoke is large and the volume of the boss member is large and the heat capacity is large, , during electric resistance welding, the initial current is large until the temperature of each member rises and the resistance increases,
Power consumption is high.

Moreover, because the initial current is large, the contact point between the boss member and the electrode that contacts the boss member and conducts the current is likely to heat up and melt, which causes the electrode to wear out quickly. Unevenness occurs due to welding. For this reason, a plate body for attaching a pad, a shock absorbing mechanism, etc. is fixed to the surface of the boss, but gaps are likely to occur between the plate body and the boss, resulting in poor fixation.

Further, when the upper and lower boss members are welded by electric resistance welding, the dimensional accuracy of the upper and lower boss members in the axial direction is not stable due to the molten state of the welded portions of the upper and lower boss members.

The present invention has been made in view of the above-mentioned points, and is composed of an upper boss member and a lower boss member that are divided in the axial direction from a boss that is fitted onto a steering shaft. In a steering wheel in which a spoke core is fixed between the spoke core metal and a plate body is fixed on the upper surface of the upper boss member, electric resistance welding can be easily performed with a small current, preventing the contact surface with the electrode from melting and preventing the electrode from melting. The purpose is to reduce wear and tear and to stabilize the dimensional accuracy of the boss.

[Structure of the invention]

(Means for Solving the Problems) The present invention comprises an upper boss member 12 and a lower boss member 14 made of metal, which are divided in the axial direction from a boss 5 that is fitted onto a steering shaft 4. A method for manufacturing a steering wheel in which a metal spoke core 6 is fixed between boss members 12 and 14 and a metal plate body 31 is fixed to the upper surface of the upper boss member 12, the method comprising: and on the upper part of the lower boss member 14,
The positioning parts 16, 20 are formed to face each other, and the welded part 18 contacts the spoke core metal 6 before the positioning parts 16, 20 come into contact with each other.
21 and abuts the plate body 31 on the upper surface of the upper boss member 12 in a small area contact state.
3, and electric resistance welding is performed under pressure between the welded parts 18, 21 of the upper and lower boss members 12, 14 and the spoke core metal 6, and between the plate body 31 and the upper surface of the upper boss member 12. However, the welding is completed by reducing the electrical resistance due to the contact between the positioning portions 16 and 20 of the upper and lower boss members 12 and 14.

(Function) In the present invention, the spoke core metal 6 is fitted between the welded parts 18 and 21 of the upper and lower boss members 12 and 14, and the plate body 31 with the protrusion 33 in contact with the upper surface of the upper boss member 12 is provided. Arrange and perform electric resistance welding. First, the protrusions 33 of the plate body 31 are heated and melted by a small current, and the plate body 31 whose temperature has increased due to the heat generated by the protrusions 33 is joined to the upper surface of the upper boss member 12. As the temperature of the plate body 31 rises and the electrical resistance increases, the upper boss member 12
The contact resistance with the upper boss member 12 is large, the temperature of the upper boss member 12 rises rapidly, and the plate body 31 is welded to the upper surface of the upper boss member 12. Furthermore, the upper boss member 1
As the temperature of upper boss member 2 increases, upper boss member 1
The welding resistance between the welding part 18 of No. 2 and the spoke core metal 6 and between the spoke core metal 6 and the welding part 21 of the lower boss member 14 increases, and the electric resistance welding conditions become favorable. The welded portions 18, 21 of the boss members 12, 14 and the spoke core metal 6 are fused and welded to each other.

Also, when performing electric resistance welding, the upper and lower boss members 1
The welded parts 18, 2 of the upper and lower boss members 12, 14 until the positioning parts 16, 20 of the upper and lower boss members 12, 14 come into contact with each other.
1 and the spoke core metal 6 generate heat and melt, and the upper and lower boss members 12 and 14 continue to approach each other, and the positioning portion 1 of the upper and lower boss members 12 and 14
6, 20 come into contact with each other, the upper and lower boss members 12, 1
Since the contact area between the positioning parts 1 and 4 increases, the electrical resistance decreases and less heat is generated.
The abutment between the upper and lower boss members 12 and 14 serves as a mechanical stopper against the approach of the upper and lower boss members 12 and 14, and welding is completed.

(Embodiment) Hereinafter, the configuration of an embodiment of the present invention will be described with reference to FIGS. 1 to 3.

2 and 3 show a steering wheel. This steering wheel has a shape in which a boss part 1 and an annular rim part 2 surrounding the boss part 1 are connected by spoke parts 3, and the boss part 1 is used for steering wheels such as automobiles. A metal boss 5 is provided which is connected to the serration portion 4a and the taper portion 4b of the shaft 4 and screwed and fixed by a nut 4c, and a spoke made of a metal round rod of the spoke portion 3 is attached to the outer side of the boss 5. The central arc-shaped part of the core metal 6 is fixed by welding,
The rim core metal 7 of the rim portion 2 is fixed to the end of the spoke core metal 6 by welding. Note that 8 is a soft synthetic resin outer covering of the rim portion 2 that covers the rim core metal 7, and 9 and 10 are synthetic resin covers for the boss portion 1 and the spoke portions 3.

As shown in FIG. 1, the boss 5 includes an upper boss member 12 having a serration hole 11 that is serration-fitted into the serration portion 4a of the steering shaft 4, and an upper boss member 12 that is tapered-fitted into the tapered portion 4b of the steering shaft 4. A lower boss member 14 is provided with a tapered hole 13.

The upper boss member 12 has serration holes 11 on the lower surface facing the lower boss member 14.
An annular joint part 15 with an outer diameter protruding from and inscribed in the central arc-shaped part of the spoke core metal 6 is provided around the spoke core 6, and a positioning part 16 is provided on the lower end surface continuing downward from the joint part 15. A fitting protrusion 17 is provided in a protruding manner, and a welded portion 18 is further formed on the outside of the joint portion 15 to be joined to the upper surface of the spoke core metal 6. On the other hand, the lower boss member 14 has a tapered hole 13 on the upper surface facing the upper boss member 12.
forming an annular fitting recess 19 located above and into which the fitting protrusion 17 is press-fitted; and forming a positioning part 20 on the bottom surface of the fitting recess 19 with which the positioning part 16 abuts; Further, on the outside of the fitting recess 19, a welding portion 21 is provided on the upper surface portion to be joined to the lower surface of the spoke core metal 6, and a step portion 2 is provided on the lower surface portion.
2 is formed.

Further, on the upper surface of the boss 5, in addition to supporting the position of the boss portion 1 of the cover 9, for example, the boss portion 1
A metal plate body 31 is fixed to which a horn mechanism, a shock absorption mechanism, etc. arranged inside the body are attached. This plate body 31 has a through hole 32 formed in the center thereof, which is slightly larger in diameter than the serration hole 11, and as shown in FIG.
A protrusion 33 is protrudingly provided on the lower surface of the upper boss member 12 at a peripheral position thereof to abut on the upper surface of the upper boss member 12 in a small area contact state. The protrusions 33 are formed by press molding at a plurality of locations on the circumference at intervals, or are continuously protruded in an annular shape, and are provided on the upper surface of the plate body 31 corresponding to the protrusions 33. A recess 34 is formed.

Then, as shown in FIG. At the same time, the central arc-shaped portion of the spoke core metal 6 is fitted into the groove formed by the welded portions 18 and 21 on the outside of the joint portion 15, and a projection is formed on the upper surface of the upper boss member 12. 33
The plate body 31 is arranged so as to be in contact with each other.

In this combined state, the lower boss member 1 is placed on the annular electrode portion 42 of the lower electrode body 41 of the electric resistance welding machine.
4 and the lower electrode body 41
The annular electrode part 44 of the upper electrode body 43 that moves toward and away from the plate body 31 is joined to the upper surface of the plate body 31, and
Electric resistance welding is performed by applying current between the electrode bodies 41 and 43 while pressing the plate body 31, upper boss member 12, and lower boss member 14 in a direction toward each other.

As a result, first, the plate body 31 has a small contact area with the upper boss member 12 and a high electric resistance.
The protrusion 33 generates heat, and this heat generation is transmitted to the entire plate body 31, which has a small heat capacity, and the temperature of the plate body 31 rises rapidly.Then, as shown in FIG. 1b, the protrusion 33 melts, and the pressure As a result, the plate body 31 is joined to the upper surface of the upper boss member 12.

Further, this plate body 31 is connected to the upper boss member 12.
When the plate body 31 is joined to the upper surface, the temperature rises and the resistance value increases, so the upper boss member 1
2, the temperature of the upper boss member 12 rises rapidly, and the plate body 31 is welded to the upper surface of the upper boss member 12.

Further, as the temperature of the upper boss member 12 increases, the welded portion 18 of the upper boss member 12 and the spoke core metal 6, which have a relatively large contact area, and the welded portion between the spoke core metal 6 and the lower boss member 14, 21
The contact resistance between the upper and lower boss members 12, 14 increases, and the electric resistance welding conditions become favorable, and the welded parts 18, 21 of the upper and lower boss members 12, 14 are melted together, and the upper and lower boss members 12, 14 are welded together by the above-mentioned pressing force. approach each other, and finally, as shown in FIG. 1c, the positioning portion 16 of the fitting protrusion 17 and the positioning portion 20 of the fitting recess 19 come into contact with each other, completing welding.

In this case, the pressurizing stroke of the electrode body 43 is not constant, but is made free, and welding is performed by adjusting the pressurizing force and current of the electrode body 43, but each boss member 1
Until the positioning portions 16 and 20 of 2 and 14 come into contact, the pressure contact portions of the boss members 12 and 14 and the spoke core metal 6 generate heat and melt, and the boss members 12 and 14 and the spoke core metal 6 at this portion The welding and the approach of both boss members 12 and 14 continue, and
When the positioning parts 16 and 20 come into contact, the area of the press-contact part between both the boss members 12 and 14 increases, so the electrical resistance to the current decreases, the heat generation of the press-contact part due to the current decreases, and the positioning The contact between the portions 16 and 20 acts as a mechanical resistance or stopper to the approach of the upper boss member 12 and the lower boss member 14, and the spoke core metal 6 is no longer welded.

Therefore, the upper boss member 12 and the lower boss member 14 are coaxially positioned by fitting the respective fitting protrusions 17 and the fitting recesses 19, and each positioning portion 1
6 and 20, the dimensional accuracy in the axial direction between the upper boss member 12 and the lower boss member 14, that is, the boss 5
The length accuracy in the axial direction of the electrode body 4 is stable, and
Even if the electrode bodies 41, 43 are somewhat worn out, the length accuracy of this boss 5 is always constant.
can be used until its original lifespan.

Further, as described above, the protrusion 33 of the plate body 31 that contacts the upper boss member 12 in a small area contact state generates heat and melts with a small current, and the temperature of the plate body 31 with a small heat capacity easily rises.
Further, this plate body 31 is connected to the upper boss member 12.
Since the temperature of the upper boss member 12 rises easily by contacting the upper boss member 12, the initial current during electric resistance welding is small, the current consumption is low, and each electrode part 42, 44, plate body 31 and lower It is possible to prevent the contact surface with the boss member 14 from melting, reduce wear of the electrode parts 42 and 44, and increase and stabilize welding strength.

After welding of the boss 5 is completed, the upper electrode body 43 is separated upward and the rod 45 disposed inside the lower electrode body 41 is raised to remove the boss 5 from the electrode body 41. Can be removed.

Furthermore, as shown in FIGS. 4a and 4b, by forming the welded portions 18 and 21 of each of the boss members 12 and 14 so that the opposing distance on the outside becomes narrower, the spoke core metal 6 is separated from the boss 5. It can prevent it from coming off.

Further, as shown in FIGS. 5 and 6 a and b, the welded portions 18 and 2 of each of the boss members 12 and 14 are
1, by forming concavities and convexities 51 and 52 in a radial manner, each boss member 1 is
2 and 14 are easily melted, making welding easier.

〔Effect of the invention〕

According to the present invention, the spoke core metal is fitted between the welded portions of the upper and lower boss members, and the plate body is disposed with the protrusion in contact with the upper surface of the upper boss member,
By performing electric resistance welding in this state, the protrusions of the plate body are heated and melted by a small current, and the temperature rises due to the heat generated by the protrusions, and the plate body, whose electrical resistance has increased, is joined to the top surface of the upper boss member. ,moreover,
The temperature of the upper boss member, which has a large contact resistance with this plate body, rises rapidly, causing contact between the welded part of the upper boss member and the spoke core metal, and between the spoke core metal and the welded part of the lower boss member. The resistance increases, the electric resistance welding conditions become favorable, and the welded parts of the upper and lower boss members and the spoke core metal are melted and welded together, so the initial current during electric resistance welding can be small. The current consumption is low, the contact surface with the electrode can be prevented from melting, the wear of the electrode can be reduced, and the welding strength is increased and stabilized.

In addition, during electric resistance welding, welding can be completed by reducing the electric resistance due to the contact between the positioning parts of both boss members, so the dimensional accuracy of the boss is stable, and the electrode pressure and welding By simply adjusting the current, electric resistance welding of both boss members can be performed with the electrode pressure stroke not constant and free, making welding easier and maintaining the dimensional accuracy of the boss even if the electrode is slightly worn out. is always constant, it is possible to use the electrode until its original lifespan, and it is also possible to automate welding work.

[Brief explanation of the drawing]

1a, b, and c are cross-sectional views of a boss portion showing one embodiment of the method for manufacturing a steering wheel of the present invention; FIG. 2 is a cross-sectional view of the steering wheel corresponding to the - view of FIG. 4A and 4B are sectional views of a boss showing another embodiment of the present invention, FIG. 5 is an exploded perspective view of a boss showing still another embodiment of the present invention, and FIG. Figures 6a and 6b are cross-sectional views of the assembled state. 4...Steering shaft, 5...Boss, 6
...Spoke core metal, 12... Upper boss member, 14
...Lower boss member, 16... Positioning part, 18...
...Welded part, 20... Positioning part, 21... Welded part, 31... Plate body, 33... Protrusion.

Claims (1)

[Claims] 1. The boss fitted to the steering shaft is composed of an upper boss member and a lower boss member made of metal, which are divided in the axial direction, and a metal spoke core metal is inserted between the upper and lower boss members. A method for manufacturing a steering wheel in which a metal plate body is fixed to the upper surface of an upper boss member, the method comprising: forming positioning portions facing each other at the lower part of the upper boss member and the upper part of the lower boss member. At the same time, before this positioning part comes into contact, a welded part that comes into contact with the spoke core metal is formed, and a protrusion that comes into contact with the upper surface of the upper boss member in a small area contact state is formed on the plate body, and the plate body and the upper side Electric resistance welding is performed under pressure between the upper surface of the boss member and between the welded parts of the upper and lower boss members and the spoke core metal, and the electrical resistance is reduced due to the abutment of the positioning parts of the upper and lower boss members. A method for manufacturing a steering wheel, characterized in that welding is finished by twisting the steering wheel.