JPH1178908A - Core bar and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lighten a core bar and reduce manufacturing costs for the core bar. SOLUTION: A boss 5, which engages in a steering shaft of an automobile, is formed by fixing an external cylinder 22 on an internal cylinder 21. The internal cylinder 21 is integrally formed using magnesium alloy. A serration part 26 which gears in the steering shaft and an oblique taper part 25 are formed on an engaging hole 24 of the internal cylinder 21. An oblique outside taper part 28 is formed on the circumference of the internal cylinder 21. The external cylinder 22 is formed with a steel product having large tensile strength. By engaging the external cylinder 22 with the circumference of the internal cylinder 21, and by pressing the engaging hole 24 with a punch 31 in one direction, the internal cylinder 21 is transformed to the circumference side and the external cylinder 22 can be fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal core provided on, for example, a steering wheel of an automobile and a method of manufacturing the metal core.

[0002]

2. Description of the Related Art Conventionally, a steering wheel of an automobile is provided with a boss constituting a metal core for connecting a steering wheel body to a steering shaft. The boss is formed in a substantially cylindrical shape provided with a fitting hole in which the steering shaft is fitted. The serration portion meshes with the steering shaft and prevents rotation in the circumferential direction. A tapered portion whose diameter decreases toward the side is formed.

In order to improve the strength of the boss, a reinforcing outer cylinder is conventionally provided on the outer peripheral side of an inner cylinder having a fitting hole as described in Japanese Utility Model Application Laid-Open No. 61-90668. Is known. In this configuration, an inner cylinder formed by forging a tubular steel material and an outer cylinder made of an aluminum alloy or a synthetic resin and formed with a cancel pin insertion hole are used so that the lower ends thereof are aligned with each other. Thus, the outer cylinder is fixed to the inner cylinder by caulking, press-fitting, bonding, welding, or the like.

[0004]

However, in the above-described conventional construction, it is difficult to reduce the weight because the inner cylinder is made of steel, and the outer cylinder is provided with a cancel pin insertion hole, so that the outer cylinder becomes large, and the entire boss is reduced. In addition to the difficulty in miniaturization, it is necessary to fix the outer cylinder to the inner cylinder by caulking while accurately positioning the outer cylinder, which has a problem that the manufacturing process is complicated.

The present invention has been made in view of the above points, and has as its object to provide a metal core and a method for manufacturing the metal core.

[0006]

According to a first aspect of the present invention, there is provided a cored bar.
An inner cylinder provided with a fitting hole to be fitted to the steering shaft, and an outer cylinder fixed to the outer peripheral side of the inner cylinder, the inner cylinder is formed of an alloy, and is formed in the fitting hole. Is formed with a serration portion that engages with the steering shaft in the circumferential direction, and a taper portion with which the steering shaft engages from the other end to the one end along the axial direction. It is formed of a material having higher tensile strength, and is fitted to and fixed to the outer peripheral portion of the inner cylinder at a position outside the tapered portion.

In this configuration, on the outer peripheral side of the inner cylinder,
Since the outer cylinder formed of a material having a higher tensile strength than the alloy constituting the inner cylinder is fixed, the inner cylinder is reinforced and the inner cylinder can be formed of an alloy. Since the inner cylinder is formed of an alloy, the weight can be easily reduced. Since the outer cylinder is provided outside the tapered portion of the inner cylinder, a jig or a steering shaft to be fitted is used to apply a force to the inner cylinder in the axial direction, thereby forming the inner cylinder made of an alloy. The tube is deformed so as to expand toward the outer peripheral side, and the inner tube and the outer tube are easily and firmly fixed.

According to a second aspect of the present invention, there is provided the cored bar according to the first aspect, wherein the inner cylinder is integrally formed with a cancel pin insertion portion that opens at least at the other end.

In this configuration, since the inner cylinder is formed of an alloy, the cancel pin insertion portion is easily formed integrally with the inner cylinder. Further, since the cancel pin insertion portion is provided in the inner cylinder, the structure of the outer cylinder can be simplified, the thickness can be reduced, and the diameter of the cored bar can be suppressed.

The core according to the third aspect is the first or second aspect.
In the core metal described above, the edge at the other end of the outer cylinder is located at one end from the edge at the other end of the inner cylinder.

In this configuration, by shifting the position of the edge between the inner cylinder and the outer cylinder, it is not necessary to increase the accuracy of the alignment between the inner cylinder and the outer cylinder, so that the manufacturing is facilitated. Interference with the cancel pin insertion portion of the cylinder is easily suppressed.

According to a fourth aspect of the present invention, there is provided a method for manufacturing a cored bar, comprising: an inner cylinder having a tapered portion having a diameter decreasing toward one end side and having a fitting hole fitted to a steering shaft; A method of manufacturing a metal core comprising an outer cylinder fixed to the outer peripheral side of the core, wherein the outer cylinder is fitted on the outer peripheral side of the tapered portion, and a force toward the one end side is applied to the tapered portion. In addition,
The outer cylinder is fixed to the inner cylinder by deforming the inner cylinder in the expanding direction.

In this configuration, the outer cylinder is fixed to the outer peripheral side of the inner cylinder to reinforce the inner cylinder, and a strong core metal is manufactured.
Therefore, it is possible to form the inner cylinder with a light material having low strength. Also, the inner cylinder is deformed in the expanding direction and the outer cylinder is easily fixed to the inner cylinder simply by fitting the outer cylinder at the outer peripheral side of the tapered part and applying a force toward one end to the tapered part. Is done.

According to a fifth aspect of the present invention, there is provided the core metal manufacturing method according to the fourth aspect, wherein an outer tapered portion is provided on an outer peripheral portion of the inner cylinder, and the outer cylinder fitted to the inner cylinder is provided with the outer cylinder. It is positioned in contact with the outer tapered portion.

In this configuration, by providing the outer tapered portion on the outer peripheral portion of the inner cylinder, the outer cylinder is positioned at a predetermined position only by fitting the outer cylinder on the outer peripheral portion of the inner cylinder, and the work can be performed. It will be easier.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a core metal and a method of manufacturing the core metal according to the present invention will be described with reference to the drawings.

2 to 4, reference numeral 1 denotes a core of a steering wheel of an automobile. A steering wheel body is formed by providing a skin portion or the like on an outer peripheral portion of the core 1, and an airbag device is attached to the steering wheel body. The steering wheel is configured by attaching such components. The steering wheel is mounted on the steering shaft 3 which is normally provided in an inclined state. Hereinafter, the description will be made with the airbag device side which is the occupant side as the upper side and the steering shaft 3 side which is the vehicle body side as the lower side. I do.

The steering wheel body has a ring-shaped rim, a boss located inside the rim, and a plurality of four rims for connecting the rim and the boss, in this embodiment. And spokes.
A boss 5 as a metal core fitted to the steering shaft 3 is provided below the boss portion, and a boss plate 6 is formed integrally with the boss 5.
A hub core set is configured. Also, the spoke cores 7 are integrally formed on the boss plate 6, and the rim cores 8 are connected to the respective spoke cores 7 by casting or the like. 1 is configured. In addition, the skin part is made of soft foamed polyurethane, etc.
The outer peripheral portion of the core bar 8 of the rim portion and the outer peripheral portion of the core bar 7 of the spoke portion on the rim side are formed. A lower cover made of a synthetic resin or the like is attached to a lower portion of the steering wheel body. Further, a substantially annular cable reel device 9 is provided on the lower side of the lower cover and is located on the outer peripheral portion of the boss 5 to electrically connect the electric component on the steering wheel side and the electric component on the vehicle body side. Is attached. In addition, the boss 5 and the boss plate 6 may be formed separately and may be formed separately and connected by welding or the like. The boss plate 6 and the core metal 7 of the spoke portion, and the spoke portion may be formed. The core metal 7 of the rim portion and the core metal 8 of the rim portion may be formed integrally, or may be formed separately and connected by welding or the like.

The steering shaft 3 is also called a steering column shaft. As shown in FIGS. 3 and 4, a fitting portion 12 is provided at a distal end portion, that is, an upper end portion of a main body portion 11 having a columnar shape. The fitting portion 12 has a shaft-side tapered portion 14 whose diameter decreases toward the distal end, and a protruding ridge formed along the axial direction, located on the distal side of the shaft-side tapered portion 14. A shaft side serration 15 is formed. Further, the fitting portion 12
Has a screw hole with a bottom
16 are formed.

On the other hand, as shown in FIGS. 1 to 6, the boss 5 is formed by combining an inner cylinder 21 and an outer cylinder 22 each having a substantially cylindrical shape.

The inner cylinder 21 is formed integrally with the boss plate 6 by casting using a die, made of a so-called light alloy, such as an aluminum alloy or a magnesium alloy, which is lighter than a steel material and can be easily cast. Further, a fitting hole 24 penetrating vertically is formed inside the inner cylinder 21. The fitting hole 24 has a tapered portion 25 located at the lower end, which is the other end side, and having a smaller diameter toward the upper side.
Are formed, and a serration portion 26 is formed on the upper end, which is one end side, and has a ridge formed along the axial direction. Further, the outer peripheral surface of the inner cylinder 21 is formed with an outer tapered portion 28 whose diameter decreases toward the lower side. And
The outer tapered portion 28 is formed to be inclined, for example, by 0.5 degrees with respect to the axial direction. Further, at the lower end of the inner cylinder 21, cancel pin insertion portions (engagement concave portions) 29 which are open to the lower side and the inner and outer peripheral sides are provided at a plurality of locations. In the present embodiment, the outer dimension (diameter) of the lower end of the inner cylinder 21 is 28 mm, the height of the inner cylinder 21 is 34.5 mm, and the inner diameter (diameter) of the lower end of the fitting hole 24 is 18.7 mm, the height of the tapered portion 25 is 14 mm, and the inner diameter (diameter) of the serration 26 is 15.2 mm at the portion where the ridge protrudes inward.
The height of the part where the ridge is formed is 14 mm, the height of the lower part where the ridge is not formed is 6.5 mm, and the inner diameter (diameter) of this part is 16.2 mm. I have.
The cancel pin insertion portion 29 is formed at two places, and has a circumferential dimension of 5 mm and a height dimension (depth) of 3 mm. Further, the draft of the outer tapered portion 28 can be set in a range of 0.5 degrees or more and 1.5 degrees or less.

The outer cylinder 22 is also called a collar, a ring, or an annular reinforcing member, and is formed in a cylindrical shape, that is, a ring shape.
It is formed to 0 mm. And this outer cylinder 22 is
It is formed of steel, which is a metal with higher tensile strength,
For example, it is formed of a metal such as iron or stainless steel having a tensile strength of 30 kg / cm 2 or more.

The outer cylinder 22 is located on the outer peripheral side of the tapered portion 25, is fitted to the outer peripheral part of the inner cylinder 21, and is fixed by deformation of the inner cylinder 21 in the outer peripheral 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.
It is aligned with the upper end of 29, or fixed slightly above the upper end of cancel pin insertion portion 29.

Next, a process of manufacturing the boss 5, that is, a process of fixing the outer cylinder 22 to the inner cylinder 21 will be described with reference to FIG.

First, the inner cylinder 21 is formed in advance into a predetermined shape by casting, and the outer cylinder 22 is formed by cutting an annular steel material into a predetermined length. Then, as shown in FIG. 1A, the inner cylinder 21 is fixed to a table or the like of a manufacturing apparatus with the tapered portion 25 facing upward, and the outer cylinder 22 is attached to the outer periphery of the inner cylinder 21. Fit by manual work. At this time,
Since the outer peripheral portion of the inner cylinder 21 has an inclined outer tapered portion 28, the outer cylinder 22 has a predetermined upper end (lower side shown in FIG. 1) in contact with the outer peripheral portion of the inner cylinder 21. Temporarily fixed in position.

Subsequently, the punch 31 which is a jig is lowered from above, and as shown in FIG. 1 (b), a pressing portion 32 having an outer peripheral portion formed into a tapered surface is inserted into the fitting hole 24 of the inner cylinder 21. Insert inside and press. Then, due to the contact between the inclined tapered portion 25 and the pressing portion 32, the tapered portion 25 of the inner cylinder 21 is pressed and deformed to the outer peripheral side, and the outer peripheral surface of the inner cylinder 21 is closely attached to the inner peripheral surface of the outer cylinder 22. Or, in a state where at least a part of the outer peripheral portion of the inner cylinder 21 is deformed so as to protrude toward the lower end side (upper side shown in FIG. 1) of the outer cylinder 22, the outer cylinder 22 is prevented from falling off to the inner cylinder 21. Fixed.

Then, by returning the punch 31 to the upper side, the boss 5 is completed as shown in FIG. 1C and FIG.

In the completed steering wheel body, the fitting hole 24 of the boss 5 is inserted into the fitting portion 12 of the steering shaft 3 so that the serration portion 26 and the shaft side serration portion 15 mesh with each other, and the tapered portion is formed. In a state where the shaft 25 and the shaft side tapered portion 14 are in contact with each other, the steering mounting bolt 33 is inserted into the fitting hole 24 from above the boss 5, that is, the boss plate 6, and the screw portion 34 of the steering mounting bolt 33 is screwed into the screw hole 16. Screwed into the steering mounting bolt 33 to form an integral or separate washer
35 comes into contact with the upper surface of the boss 5, and the steering shaft 3 is fixed so as not to come off. Further, in this state, the shaft-side tapered portion 14 is pressed against the tapered portion 25, and the inner cylinder 21 is further pressed toward the outer cylinder 22, so that the inner cylinder 21 and the outer cylinder 22 are more firmly fixed.

According to the present embodiment, the outer cylinder 22 made of a metal having a higher tensile strength and less plastic deformation than the light alloy constituting the inner cylinder 21 is fixed to the outer peripheral side of the inner cylinder 21. The inner cylinder 21 is reinforced, and can be protected from a force applied at the time of a collision of an automobile or mounting of a steering wheel.

Since the inner cylinder 21 is reinforced by the outer cylinder 22, the inner cylinder 21 can be formed of a lightweight alloy such as an aluminum alloy or a magnesium alloy. Therefore, the weight of the boss 5 can be easily reduced, and the boss 5 can be easily formed using a mold, so that the manufacturing cost can be reduced. In particular, the production cost can be reduced by using an aluminum alloy, and the strength can be easily improved by using a magnesium alloy.

Then, the cancel pin insertion portion 29 is inserted into the inner cylinder 21.
Since the outer cylinder 22 can be easily formed integrally, the structure of the outer cylinder 22 can be simplified. For example, the outer cylinder 22 can be easily formed using a pipe material having the same inner diameter, and the manufacturing cost can be reduced. In addition, the outer cylinder 22 can be made thinner, and the diameter of the boss 5 can be reduced. Further, when the steering wheel is mounted on the actual vehicle, the shaft side tapered portion 14 of the steering shaft 3 is pressed against the tapered portion 25, and the inner cylinder 21 is further pressed toward the outer cylinder 22, so that the entire inner surface of the outer cylinder 22 is Are completely adhered to the inner cylinder 21, and the inner cylinder 21 can be reinforced by the outer cylinder 22 having a large tensile strength. Therefore, it is not necessary to increase the diameter of the boss 5. For example, the cable reel device 9 is arranged around the boss 5, and the distance between the inner diameter of the cable reel device 9 and the outer shape of the inner cylinder 21 of the boss 5 is reduced. The outer cylinder 22 can be easily arranged in this gap even if the dimensional difference of the outer cylinder 22 is only about 3 mm.

Since the outer cylinder 22 is provided outside the tapered portion 25 of the inner cylinder 21, the jig is moved only in one direction while being fitted to the outer periphery of the inner cylinder 21. The inner cylinder 21 formed of an alloy can be deformed in the expanding direction so that the inner cylinder 21 and the outer cylinder 22 can be easily and firmly fixed, and at least the outer cylinder 22 falls off during transportation of the steering wheel until the actual vehicle is mounted. The manufacturing cost can be reduced as compared with a configuration in which the outer cylinder is crimped inward.

Further, by providing the outer tapered portion 28 on the outer peripheral portion of the inner cylinder 21, the outer cylinder 22 can be positioned at a predetermined position only by fitting the outer cylinder 22 to the outer peripheral portion of the inner cylinder 21. Work can be facilitated and manufacturing costs can be reduced. The outer tapered portion 28 can also be used as a draft when the inner cylinder 21 is cast.

Further, by shifting the positions of the lower ends of the inner cylinder 21 and the outer cylinder 22, it is not necessary to increase the accuracy of the alignment between the inner cylinder 21 and the outer cylinder 22, thereby facilitating the manufacture.
The interference of the outer cylinder 22 with the cancel pin insertion portion 29 can be easily suppressed, and the manufacturing cost can be reduced.

In the above-described embodiment, the cancel pin insertion portions 29 opened to the lower side and the inner and outer peripheral sides are formed at two places at the lower end of the inner cylinder 21. The arrangement and the like can be appropriately adjusted to the shape and arrangement of the cancel pin. For example, FIGS. 7 and 8
As shown in (1), a bottomed hole-shaped cancel pin insertion portion (cancel pin hole) 41 that opens only on the lower side can be formed at three places. Note that this cancel pin insertion part
41 has an inner diameter (diameter) of 4.7 mm.

The dimensions of the outer cylinder with respect to the inner cylinder can be appropriately selected. For example, almost the entire inner cylinder can be covered with the outer cylinder.

The metal core can be used for various steering devices in addition to automobiles.

[0038]

According to the core of the present invention, since the outer cylinder formed of a material having a higher tensile strength than the alloy constituting the inner cylinder is fixed to the outer peripheral side of the inner cylinder, the inner cylinder is reinforced. The inner cylinder can be formed of an alloy. Since the inner cylinder is formed of an alloy, the weight can be easily reduced. Further, since the outer cylinder was provided outside the tapered portion of the inner cylinder, the outer cylinder was formed of an alloy by applying a force along the axial direction to the inner cylinder by a jig or a steering shaft to be fitted. The inner cylinder is deformed so as to expand toward the outer peripheral side, so that the inner cylinder and the outer cylinder can be easily and firmly fixed.

According to the core of the second aspect, in addition to the effect of the first aspect, since the inner cylinder is formed of an alloy, the cancel pin insertion portion can be easily formed integrally with the inner cylinder. In addition, since the cancel pin insertion portion is provided in the inner cylinder, the structure of the outer cylinder can be simplified, manufacturing costs can be reduced, and the outer cylinder can be made thinner and the diameter of the cored bar can be reduced. .

According to the core metal of the third aspect, in addition to the effect of the first or second aspect, the position of the inner cylinder and the outer cylinder is shifted by shifting the position of the edge of the inner cylinder and the outer cylinder. It is not necessary to increase the alignment accuracy, and the manufacturing can be facilitated, and the interference of the outer cylinder with the cancel pin insertion portion can be easily suppressed, and the manufacturing cost can be reduced.

According to the method for manufacturing a cored bar according to claim 4,
The outer cylinder is fixed to the outer peripheral side of the inner cylinder to reinforce the inner cylinder, and a strong core metal can be manufactured. Therefore, the inner cylinder can be formed of a low-strength, lightweight material, and the weight of the cored bar can be reduced. Further, the outer cylinder is fitted on the outer peripheral side of the tapered portion, and only by applying a force toward the one end to the tapered portion, the inner cylinder is deformed in the expanding direction,
The outer cylinder can be easily fixed to the inner cylinder, and the manufacturing cost can be reduced.

According to the manufacturing method of the core metal according to the fifth aspect,
In addition to the effect of the fourth aspect, by providing the outer tapered portion on the outer peripheral portion of the inner cylinder, the outer cylinder can be positioned at a predetermined position only by fitting the outer cylinder on the outer peripheral portion of the inner cylinder. The manufacturing cost can be reduced easily.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a manufacturing process showing an embodiment of a core metal of the present invention. (A) Initial state (b) State following (a) (c) State following (b)

FIG. 2 is a perspective view of a steering wheel main body provided with the above metal core, viewed from a lower surface side of a core body.

FIG. 3 is an explanatory view showing a process of attaching the core metal to a steering shaft.

FIG. 4 is a cross-sectional view showing a state where the core metal is attached to a steering shaft.

FIG. 5 is a side view of the core metal.

FIG. 6 is an exploded perspective view of the core metal.

FIG. 7 is a sectional view showing another embodiment of the cored bar of the present invention.

FIG. 8 is a perspective view of a part of the core metal.

[Explanation of symbols]

 3 Steering shaft 5 Boss as core metal 21 Inner tube 22 Outer tube 24 Fitting hole 25 Taper portion 26 Serration portion 28 Outer taper portion 29, 41 Cancel pin insertion portion

Claims (5)

[Claims] 1. An inner cylinder having a fitting hole to be fitted to a steering shaft, and an outer cylinder fixed to an outer peripheral side of the inner cylinder, wherein the inner cylinder is formed of an alloy, The fitting hole is formed with a serration portion that engages with the steering shaft in the circumferential direction, and a tapered portion with which the steering shaft engages from the other end to one end along the axial direction. A core bar formed of a material having a higher tensile strength than the alloy, and fitted and fixed to the outer peripheral portion of the inner cylinder at a position outside the tapered portion. 2. The cored bar according to claim 1, wherein a cancel pin insertion portion opened at least on the other end side is formed integrally with the inner cylinder. 3. The cored bar according to claim 1, wherein the edge on the other end side of the outer cylinder is located at one end side from the edge on the other end side of the inner cylinder. 4. An inner cylinder provided with a fitting hole which is provided with a tapered portion whose diameter decreases toward one end side and which is fitted to a steering shaft, and an outer cylinder fixed to an outer peripheral side of the inner cylinder. A method of manufacturing a metal core, comprising: fitting the outer cylinder at an outer peripheral side of the tapered portion, applying a force toward the one end to the tapered portion, and expanding the inner cylinder in the expanding direction. A method for manufacturing a metal core, comprising deforming and fixing the outer cylinder to the inner cylinder. 5. The cored bar according to claim 4, wherein an outer tapered portion is provided on an outer peripheral portion of the inner cylinder, and an outer cylinder fitted to the inner cylinder is positioned in contact with the outer tapered section. Production method.