GB2329008A

GB2329008A - Coupling of a steering wheel to a steering shaft

Info

Publication number: GB2329008A
Application number: GB9819252A
Authority: GB
Inventors: Izumi Sato; Toshihide Kato; Naoki Yamamoto
Original assignee: Nihon Plast Co Ltd
Current assignee: Nihon Plast Co Ltd
Priority date: 1997-09-04
Filing date: 1998-09-03
Publication date: 1999-03-10
Anticipated expiration: 2018-09-03
Also published as: GB2329008B; DE19840229A1; JP3114928B2; GB9819252D0; JPH1178908A

Abstract

A hub 5 fitted on a steering shaft of a vehicle is formed by fixing a collar 22 to an inner cylinder 21 of the steering wheel made of aluminium alloy or magnesium alloy. A serration 26 for interlocking with the steering shaft, and an inclined taper 25 are formed in a fitting hole 24 of the inner cylinder. The collar has a greater tensile strength than the inner cylinder, preferably being made of steel. The collar is fitted on the inner cylinder and the fitting hole is acted on by a punch so that the inner cylinder is deformed toward the outer cylinder to fix it.

Description

j 2329008 CORE BAR FOR STE9RING W#4]Eei- The present invention relates to

a core bar installed s in a steering wheel of a vehicle and a method of producing same.

Conventionally, the steering wheel of the vehicle comprises a boss comprising the core bar. The core bar connects a steering wheel main body with a steering shaft.

lo The boss is formed in a substantially cylindrical shape and comprises a fitting hole for fitting with the steering shaft. The fitting hole comprises a serration portion and a taper portion. The serration portion locks a circumferential movement by interlocking with the steering shaft. The taper portion becomes smaller in diameter toward a tip end side.

In order to improve the strength of the boss, as disclosed in Japanese Unexamined (K0KA1) Utility Model Publication No. 61(1986)-90668, a construction in which an outer cylinder for reinforcing is installed around an inner cylinder comprising the fitting hole is known. In the construction, the outer cylinder is fixed to the inner cylinder by caulking, press fitting, adhesion or welding after positioning the lower end portions of the outer 2s cylinder and the inner cylinder. The inner cylinder is formed by forging a cylindrical steel product. The outer cylinder is formed by an aluminum alloy or a synthetic resin and comprises cancel pin inserting holes.

However, in the above-mentioned construction, it is hard to lighten the boss because the inner cylinder is formed by the steel product, the outer cylinder is oversized because the cancel pin inserting holes are formed on the outer cylinder and thereby miniaturizing of 2- the whole boss is hard and manufacturing process is complicated because it is necessary to caulk by an accurate positioning of the outer cylinder against the inner cylinder.

It is therefore an object of the present invention to provide a core bar and a method of producing same.

A core bar according to the present invention comprises:

an inner cylinder comprising a fitting hole for receiving a steering shaft and an outer cylinder fixedly mounted on an outer circumference of the inner cylinder, said inner cylinder being formed of an alloy, said fitting hole comprising a serration portion for engaging with said steering shaft in a circumferential direction and a taper portion for engaging said steering shaft along an axial direction from an other end side to one end side, and said outer cylinder being formed of a material having a tensile strength greater than a tensile strength of said alloy and being fitted to a position surrounding said taper portion of said inner cylinder.

According to the core bar, because the outer cylinder of the material having a tensile strength greater than the tensile strength of the alloy forming the inner cylinder is fixed to the outer circumferential side of the inner cylinder, the inner cylinder is reinforced and thereby it is possible to form the inner cylinder of an alloy. Because the inner cylinder is formed by the alloy, it is easily possible to lighten the inner cylinder. Because the outer cylinder is positioned at the outside of the taper portion of the inner cylinder, the force applied to the inner cylinder along an axial direction by a jig or a steering shaft fitted with the outer cylinder makes the inner cylinder formed by the 3 alloy deformed so as to open toward the outer circumferential side and the outer cylinder is fixed easily and tightly with the inner cylinder.

According to the core bar, because the inner cylinder is formed by the alloy, cancel pin inserting portions are easily formed integrally with the inner cylinder. Because the cancel pin inserting portions are formed in the inner cylinder, it is possible to simplify the structure of the outer cylinder, to make the outer cylinder thinner and to io limit the diameter of the core bar.

According to the core bar, when the end portions of the inner cylinder and the outer cylinder are shifted, it is not necessary to improve the accuracy of the positioning of the inner cylinder and the outer cylinder, manufacturing becomes easy and the interference of the outer cylinder into the cancel pin inserting portions is limited.

According to the method of producing the core bar, the inner cylinder is reinforced by fixing the outer cylinder to the outer circumferential side of the inner cylinder and thereby the firm core bar is produced. Thus, it is possible to form the inner cylinder by a light material having a low strength. The outer cylinder is fitted with the outer circumferential side of the taper portion and the force directing to one end side is applied to the taper portion. Thus, the inner cylinder is deformed toward an opening direction and the outer cylinder is easily adhered to the inner cylinder.

According to the method of producing the core bar, the outside taper portion is formed on the outside circumferential side of the inner cylinder and the outside cylinder is fitted with the outside circumferential portion of the inner cylinder. Thus, the outer cylinder is positioned at a predetermined position and working becomes easy. BRIEF DESCRIPTION OF THE DRAWING.5

Fig. 1A is an explanatory view showing an initial condition of a manufacturing process of one embodiment of a core bar of the present invention.

Fig. 113 is an explanatory view showing a second condition following the initial condition of the manufacturing process of the embodiment of the core bar jo of the present invention.

Fig. 1C is an explanatory view showing a third condition following the second condition of the manufacturing process of the embodiment of the core bar of the present invention.

Fig. 2 is a perspective view seen from a lower surface side of a core body of a steering wheel main body comprising the core bar of Figs. 1A, 1Band 1C.

Fig. 3 is an explanatory view showing an installing process of the core bar of Figs. 1A, 1B, and 1C around a 20 steering shaft.

Fig. 4 is a sectional view showing a state in which the core bar of Figs. 1A, 1B, and 1C is installed around the steering shaft.

Fig. 5 is a side view of the core bar of Figs. 1A, 1131 25 and 1C.

Fig. 6 is an exploded perspective view of the core bar of Figs. 1A, 1B, and 1C.

Fig. 7 is a sectional view showing another embodiment of a core bar of the present invention.

Fig. 8 is a perspective view of a part of the core bar of Fig. 7.

is DETAILED DESCRIPTION

The following is an explanation of one embodiment of a core bar (or hub member) and a method of producing same,according to the present invention, with reference to the drawings. In Figs. 2 through 4, reference numeral 1 shows a core body (or structural member) of a steering wheel of a vehicle. A steering wheel main body comprises an outer cover covering the core body 1. The steering wheel further comprises an air bag unit. The steering wheel is installed on a steering shaft 3. The steering shaft 3 is usually provided in an oblique state. The air bag side which is a passenger side is hereinafter called an upper side and the steering shaft 3 side which is the vehicle body side is hereinafter called a lower side.

The steering wheel main body comprises an annular rim portion, a boss portion.and a plurality of spoke portions. The boss portion is positioned inside the rim portion. The spoke portions connect the rim portion with the boss portion. In the present embodiment, the number of the spoke portions is four. A boss 5 is located at a lower portion of the boss portion. The boss (or hub) 5 fits over the steering shaft 3 and serves as a core bar. A boss plate 6 is formed integrally with the boss 5 and thereby a hub core set is formed. Core bars 7 of the spoke portions 2-5 are formed integrally with the boss plate 6. A core bar 8 of the rim portion is covered and connected with the core bar 7 of each spoke portion by casting in the form of an insert. The core body 1 is thus formed. The outer cover is made of soft polyurethane foam, for example, and forms an outer circumference of the core bar 8 of the rim portion and an outer circumference of a portion of the rim portion side of the core bars 7 of the spoke portions. A lower cover is installed on a lower portion of the steering 6 wheel main body. The lower cover is made of a synthetic resin. A substantially annular cable reel unit 9 is installed on a lower part of the lower cover so as to surround the boss 5. The cable reel unit 9 connects electrical components in the steering wheel with electrical components on the vehicle's side. The boss 5 can be formed integrally with the boss plate 6. Alternatively, the boss 5 and the plate may be separate members joined together by welding, for example. The boss plate 6 can lo be formed integrally with the core bars 7 of the spoke portions or can be separately formed and connected by welding. The core bars 7 of the spoke portions can be formed integrally with the core bar 8 of the rim portion or can be separately formed and connected by welding.

The steering shaft 3 is also called a steering column shaft. As shown in Figs. 3 and 4, the steering shaft 3 comprises a columnar main body portion (or shank) 11 and an upper end portion (or fitted portion) 12 extending upwardly from the upper end of the shank 11. The upper end portion 12 comprises a tapered shaft section (or shaft side taper portion) 14 and a serrated shaft section (or shaft side serration portion) 15. The shaft side taper portion 14 is conical and becomes smaller in diameter toward the tip end. The shaft side serration 15 is positioned on the tip end side of the shaft side taper portion 14 and comprises a ridge extending along the axial direction. The fitted portion 12 comprises a screw hole 16 which is a fixed portion. The screw hole 16 opens in the tip end and has a bottom. The screw hole 16 in this example is a blind hole.

On the other hand, the boss 5 comprises an inner cylinder (or inner cylindrical portion) 21 and an outer cylinder (or collar) 22. The inner cylinder 21 and the 7 outer cylinder 22 are substantially in the form of a hollow circular cylinder as shown in Figs. 1A through 6.

The inner cylinder 21 is made of light alloy or light metal such as aluminum alloy or magnesium alloy which is fighter than steel and easier to cast by casting using a metal mold. In this example, the inner cylinder 21 is formed integrally with the boss plate 6. A fitting center hole 24 is formed inside the inner cylinder 21. The fitting hole 24 passes axially (or up and down) through the inner jo cylinder 21. The fitting hole 24 comprises a taper portion (or flare section) 25 at a lower side which is other end side and a serration portion (or serrated section) 26 at an upper side which is one end side. The taper portion 25 becomes gradually smaller in diameter along lengthwise direction from the lower end toward the upper side. The serration portion 26 comprises a plurality of ridges extending along the axial direction. In the outside circumference surface of the inner cylinder 21, there is formed an outside taper portion 28 which becomes gradually smaller in diameter toward the lower end. The outside taper portion 28 is formed so as to incline 0.50 with respect to the axial direction. A plurality of cancel pin inserting portions (engaging concave portions) 29 are formed in the lower end of the inner cylinder 21. Each of the cancel pin inserting portions 29 of this example is a rectangular groove formed in the lower end of the inner cylinder 21 and extending radially from an outer groove end opening in the outside cylindrical surface of the inner cylinder 21 to an inner groove end opening in the inside cylindrical surface of the inner cylinder 21. In this example, the outside dimension (diameter) of the lower end of the inner cylinder 21 is 28 nim, the height of the inner cylinder 21 is 34.5 mm, the inside dimension 8 (diameter) of the lower end of the fitting hole 24 is 18.7 MM, and the height of the taper portion 25 is 14 mm. The inside dimension (diameter) of the serrated portion at the inwardly projection ridges is 15.2 inm, the height of the portion where the ridges are formed is 14 mm, the height of the lower side portion where no ridges are formed is 6.5 min and the inner dimension of the lower side portion where no ridges are formed is 16.2 mm. Two of the cancel pin inserting portions 29 are formed. A dimension along a lo circumferential direction of each of the cancel pin inserting portions 29 is 5 mm and a height (depth) of each of the cancel pin inserting portions 29 is 3 mm. A draft (or degree of taper) of the outside taper portion 28 can be set equal to or greater than 0.50 and equal to or smaller than 1.50.

The outer cylinder 22 is also called a collar, a ring, or an annular reinforcement and is formed in a hollow cylindrical shape, that is, a ring shape. For example, the thickness of the outer cylinder 22 is 1 mm and the height of the outer cylinder 22 is 10 mm. The outer cylinder 22 is made of a steel.which is a metal having a tensile strength greater than a tensile strength of the metal forming the inner cylinder 21. For example, the outer cylinder 22 is formed by iron or an iron based alloy or a stainless steel having a tensile strength greater than 30 kg/cm The outer cylinder 22 is located at a position surrounding the tapered portion 25, and fits over the outer circumferential surface of the inner cylinder 21. The outer cylinder 22 is fixedly held immovable by expanding deformation of the inner cylinder 21 in the radial outward direction. When the outer cylinder 22 is fixed, the lower end of the outer cylinder 22 is positioned above the lower end of the inner cylinder 21. For example, the lower end 9 of the outer cylinder 22 is aligned with the upper ends of the cancel pin inserting portions 29 so that the lower end of the outer cylinder 22 and the upper ends of the cancel pin inserting portions 29 are located evenly at the same s level. Alternatively, the lower end of the outer cylinder 22 is positioned slightly above the upper ends of the cancel pin inserting portions 29. Thus, the lower end portion of the inner cylinder 21 projects downwards as shown in Fig. 5 from the lower end of the outer cylinder io 22.

The following is an explanation of a manufacturing process of the boss 5, that is, a process in which the outer cylinder 22 is fixed to the inner cylinder 21 with reference to Figs. 1A, 1B, and 1C and so on.

The inner cylinder 21 is preliminarily formed by casting into a predetermined shape and the outer cylinder 22 is formed by cutting an annular steel product to have a predetermined length. As shown in Fig. 1A, the inner cylinder 21 is placed and held immovable on a table of manufacturing equipment in an inverted state that the taper portion 25 faces upwards. Then, the outer cylinder 22 is fitted over the outer circumferential portion of the inner cylinder 21 from above by hands, for example. In this state, the conical surface of the outside taper portion 2s 28 tapering upwards limits the downward movement of the outer cylinder 22 around the outside taper portion 28, and holds the outer cylinder 22 immovable at a predetermined position in a state that the upper end of the outer cylinder 22 (the lower end as viewed in Figs. 1A, 1B.and 1C) is engaged with the outside conical surface of the inner cylinder 21.

As shown in Fig. 1B, a punch 31 which is a jig is lowered from above and a pressing portion 32 of the punch 31 having a tapered outside circumferential (conical) surface tapering downward is inserted and pressed into the fitting hole 24 of the inner cylinder 21. By the engagement between the inclined taper portion 25 and the pressing portion 32, the taper portion 25 of the inner cylinder 21 is pressed and deformed radially outwardly and thereby the outer cylinder 22 is locked and fixed immovable and unextractable in a state that the outer circumferential surface of the inner cylinder 21 is lo stuck to the inner surface of the outer cylinder 22 or at least a part of the outer circumferential portion of the inner cylinder 21 is deformed so as to project and expand beyond the lower end of the outer cylinder 22 (the upper side as viewed in Figs. 1A, 1B,and 1C).

When the punch 31 is pulled upward, as shown in Figs. 1C and 5, the boss 5 is completed.

In the completed steering wheel main body, a steering installing bolt 33 is inserted into the fitting hole 24 from the upper side of the boss plate 6 of the boss 5 in the state that the fitted portion 12 of the steering shaft 3 is inserted into the fitting hole 24 of the boss 5, the serration portion 26 is engaged with the shaft side serration 15 and the taper portion 25 is fitted over the shaft side taper portion 14. The threaded portion 34 of the steering installing bolt 33 is screwed into the screw hole 16 and tightened and thereby a washer portion 35 which is integral with, or separate from the steering installing bolt 33 is pressed against the upwardly facing surface of the boss 5. In this way, the steering shaft 3 is locked and fixed unextractable. In this state, the shaft side taper portion 14 is pressed against the taper portion 25 and the inner cylinder 21 is pressed against the outer 1 11 cylinder 22, so that the inner cylinder 21 and the outer cylinder 22 are more rigidly fixed together.

In the present embodiment, the outer cylinder 22 is made of the metal which has the tensile strength greater s than the tensile strength of the light alloy of the inner cylinder 21 and which is hard to be plastically deformed, and the outer cylinder 22 is fixed around the outer circumferential surface of the inner cylinder 21 so as to constrict the inner cylinder 21. The outer cylinder 22 can lo reinforce the inner cylinder 21 and protect against a force caused during a vehicle collision or during assembly process of the steering wheel.

Because the inner cylinder 21 is reinforced by the outer cylinder 22, it is possible to form the inner cylinder 21 by the light alloy such as the aluminum alloy or the magnesium alloy. Thus, it is easily possible to lighten the boss 5, to easily form by using the mold and to reduce manufacturing cost. The use of aluminum alloy can reduce the manufacturing cost and the magnesium alloy is advantageous to strengthen the product.

Because it is easy to form the cancel pin inserting portions (holes, recesses.or cutouts) 29 integrally in the inner cylinder 21, it is possible to simplify the structure of the outer cylinder 22. For example, it is possible to reduce the manufacturing cost by producing the outer cylinder 22 from a pipe having the correct inner diameter. It is further possible to make the diameter of the boss 5 small by making the outer cylinder 22 thinner. In the assembled state of the steering wheel on the vehicle, the inner cylinder 21 is pressed tightly and intimately between the shaft side taper portion 14 of the steering shaft 3 and the outer cylinder 22, and the entirety of the inside surface of the outer cylinder 22 is in contact with the 12 outside surface of the inner cylinder 21. Thus, the outer cylinder 22 having a greater tensile strength can efficiently reinforce the inner cylinder 21. Thus, there is no need to make the boss 5 to be large in diameter. For example, when the cable reel unit 9 is installed on the circumference of the boss 5, even if the difference between the inner diameter of the cable reel unit 9 and the outer diameter of the inner cylinder 21 is only about 3 MM, it is easy to install the outer cylinder 22 in the gap.

Because the outer cylinder 22 is installed on the outside of the taper portion 25 of the inner cylinder 21, in a state that the outer cylinder 22 is fitted with the outer circumferential portion of the inner cylinder 21, only one direction movement of the jig can make the inner cylinder 21 formed by the alloy deformed toward the opening direction and the inner cylinder 21 and the outer cylinder 22 can be easily and tightly fixed. At least, it is possible to prevent the outer cylinder 22 from failing down during the transportation of the steering wheel before mounting on the vehicle and it is possible to reduce manufacturing cost as compared with the construction in which the outer cylinder 22 is caulked into the inside.

Because the outside taper portion 28 is formed on the outer circumferential portion of the inner cylinder 21, it is possible to position the outer cylinder 22 at a desired position merely by placing the outer cylinder 22 around the inner cylinder 21. This facilitates the assembly process and reducesthe manufacturing cost. The outside taper portion 28 can also be used as the draft facilitating extraction of casting during the casting process of the inner cylinder 21.

Further, by the lower end portions of the inner cylinder 21 and the outer cylinder 22 being shifted and 1 43 not aligned, it is not necessary to improve the accuracy of the positioning of the inner cylinder 21 and the outer cylinder 22, so that the production can become easier, it is possible to prevent the interference between the outer cylinder 22 and the cancel pin inserting portions 29, and it is possible to reduce the manufacturing cost.

In the example shown above, the two cancel pin inserting portions 29 are formed in the lower end portion of the inner cylinder 21, each of the cancel pin inserting io portions 29 can be in the form of a recess opening in the lower end of the inner cylinder 21 and extending from the inner circumferential surface to the outer circumferential surface, however, it is possible to employ various other shapes and arrangements for the cancel pin inserting is portions in accordance with the shape and arrangement of the cancel pins. For example, as shown in Figs. 7 and 8, it is possible to form three cancel pin inserting portions (cancel pin holes) 41. Each of the cancel pin inserting portions 41 has an open end opening in the lower end of the inner cylinder 21, and extending axially to a bottom. In this example, each cancel pin inserting portion 41 is in the form of a circular blind hole, and the inner dimension (diameter) of each cancel pin inserting hole 41 is 4.7 m.

The dimension of the outer cylinder for the inner cylinder can be suitably selected. For example, the outer cylinder can cover substantially the whole surface of the inner cylinder.

The core bar can be used in vehicles and various other steering apparatuses.

According to the core bar, because the outer cylinder formed by the material having the tensile strength greater than the tensile strength of the alloy forming the inner cylinder is fixed to the outer circumferential side of the 11- inner cylinder, it is possible to reinforce the inner cylinder and to form the inner cylinder by the alloy. Because the inner cylinder is formed by the alloy, it is easily possible to lighten the inner cylinder. Because the outer cylinder is positioned at the outside of the taper portion of the inner cylinder, the force applied to the inner cylinder along the axial direction by the jig or the steering shaft fitted with the outer cylinder makes the inner cylinder formed by the alloy deformed so as to open toward the io outer circumferential side and the inner cylinder and the outer cylinder can be fixed easily and tightly.

According to the core bar, because the inner cylinder is formed by the alloy, the cancel pin inserting portions can be easily formed integrally with the inner cylinder.

Because the cancel pin inserting portions are formed in the inner cylinder, it is possible to simplify the structure of the outer cylinder, to reduce manufacturing cost, to make the outer cylinder thinner and to make the diameter of the core bar small.

According to the core bar, when the end portions of the inner cylinder and the outer cylinder are shifted, it is not necessary to improve the accuracy of the positioning of the inner cylinder and the outer cylinder, it is easy to form, it is possible to prevent the interference of the outer cylinder into the cancel pin inserting portions and it is possible to reduce manufacturing cost.

According to the producing method of the core bar, the inner cylinder is reinforced by fixing the outer cylinder to the outer circumferential side of the inner cylinder and thereby the firm core bar can be produced. Thus, it is possible to produce the inner cylinder by a light material having lower strength and thereby it is possible to lighten the core bar. The outer cylinder is fitted with the outer circumferential side of the taper portion and the force directing to one end side is applied to the taper portion. Thus, it is possible to deform the inner cylinder toward the opening direction., to easily adhere the outer cylinder to s the inner cylinder and to reduce manufacturing cost.

According to the producing method of the core bar, the outside taper portion is formed on the outer circumferential side of the inner cylinder and the outer cylinder is fitted with the outer circumferential portion of jo the inner cylinder. Thus, it is possible to position the outer cylinder at a predetermined position, to make working easy, and to reduce manufacturing cost.

2 16

Claims

CLAIMS:

1 A core bar comprising:

an inner cylinder comprising a fitting hole for 3 receiving a steering shaft and an outer cylinder fixedly 4 mounted on an outer circumference of the inner cylinder, said inner cylinder being formed of an alloy, said fitting 6 hole comprising a serration portion for engaging with said 7 steering shaft in a circumferential direction and a taper 8 portion for engaging said steering shaft along an axial 9 direction from an other end side to one end side, and said outer cylinder being formed of a material having a tensile 11 strength greater than a tensile strength of said alloy and 12 being fitted to a position surrounding said taper portion of 13 said inner cylinder.

2. A core bar as claimed in Claim 1 wherein the inner cylinder is formed integrally with a cancel pin inserting portion which opens at least at said other end side.

4 1 2

3. A core bar as claimed in Claim 1 wherein an edge portion of the other end side of the outer cylinder is positioned closer to the one end side than an edge portion of the other end side of the inner cylinder.

4. A method of producing a core bar comprising an inner cylinder comprising a fitting hole for fitting a 3 steering shaft comprising a taper portion becoming smaller 4 in diameter toward one end side and an outer cylinder fixed to outer circumferential side of the inner cylinder, in which method 7 (a) said outer cylinder is positioned at and fitted with 8 an outer circumferential side of said taper portion 9 (b) a force directing to one end side is applied to said jo taper portion, said inner cylinder is deformed into an 1-7 1:1 opening direction and said outer cylinder is fixed to said 12 inner cylinder.

1

5. A method of producing a core bar as claimed in Claim 2 4 wherein an outside taper portion is formed on an outer 3 circumferential portion of the inner cylinder and the outer 4 cylinder fitting with the inner cylinder is engaged and !5 positioned with the outside taper portion.

6. A core bar as claimed in Claim 1 wherein the inner 2 cylinder is formed by the alloy such as an aluminum alloy, 3 a magnesium alloy and the outer cylinder is formed by 4 steel and a stainless and so on.

7 1 7. A hub assembly for supporting a steering wheel on a 2 steering shaft, comprising:

3 a hub member which comprises a support portion for 4 supporting the steering wheel and an inner hollow -5 cylindrical portion which is made of first metallic material 6 and formed with a center hole for receiving the steering shaft, the center hole comprising a flare section in which a

8 sectional size is increased gradually to a lower hole end;

9 and a collar fitting over the inner hollow cylindrical portion, 11 binding the inner hollow cylindrical portion by encircling the 12 flare section, and being made of second metallic material 13 having a tensile strength greater than a tensile strength of 14 the first metallic material.

1 8. A hub assembly as claimed in Claim 7 wherein the 2 inner cylindrical portion of the hub member is formed with 3 at least one cancel pin inserting portion opening in a lower 4 end of the inner cylindrical portion of the hub member.

4 1:3 3 1 9. A hub assembly as claimed in Claim 8 wherein the 2 lower end of the inner cylindrical portion of the hub member projects from the collar.

10. A hub assembly as claimed in Claim 7 wherein the 2 inner cylindrical portion of the hub member is made of light 3 metal, and the collar is made of steel.

1

11. A hub assembly as claimed in Claim 7 wherein the 2 collar is fixed unextractable around the inner cylindrical 3 portion of the hub member by expanding deformation of 4 the inner cylindrical portion.

6 7 1

12. A method of producing a hub assembly for supporting 2 a steering wheel on a steering shaft, comprising steps of:

3 (a) producing a hub member which comprises a support portion for supporting the steering wheel and an inner hollow cylindrical portion which is made of first metallic material and formed with a center hole for receiving the steering shaft, the center hole comprising a 8 flare section in which a sectional size is increased gradually to a lower end of the inner cylindrical portion; (b) positioning a collar around the flare section; and 11 (c) deforming the inner cylindrical portion so as to 12 expand radially outwardly until the collar is fixed

13 unremovable from the inner cylindrical portion.

4 1 13. A method according to Claim 12 wherein the inner 2 cylindrical portion produced by the first step comprises an 3 outside tapered portion tapering in sectional size to the lower end of the inner cylindrical portion.

14. A method according to Claim 13 wherein in the second 2 step, the hub member is placed upside down, and the 19 Document #: 301391 outside tapered portion holds the collar at a predetermined level surrounding the flare secUon.

15. A core bar substantially as described with reference to, and as shown in, Figures 1A to 6 or Figures 7 and 8 of the accompanying drawings.

16. A method of producing a core bar, substantially as described with reference to Figures 1 A to 1 C of the accompanying drawings.

17. A hub assembly substantially as described with reference to, and as shown in, Figures 2 to 6 or Figures 7 and 8 of the accompanying drawings.

18. A method of producing a hub assembly, substantially as described with reference to the accompanying drawings.