JPH0920254A - Collapsible tube and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a collapsible tube to have no discontinuous part against strength and rigidity and the excellent absorption efficiency of a shock energy. SOLUTION: A collapsible tube comprises a bellows part 1 consisting of a plurality of large parts 11 and small parts 19; and coupling parts formed in succession to the bellows part 1 and coupled to the other member. The bellows part 1 and the coupling part 2 are integrally molded through various plastic processing means based on a thick section-form hollow pipe made of a metal. Thus, since all parts are formed through the plastic processing means based on a single member, the flow of a material texture is unified in a specified direction and thus, strength and rigidity are uniformized. As a result, the absorption efficiency of shock energy is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a collapsible tube which is provided on a part of a steering shaft and serves to absorb impact energy applied to the steering shaft.
The present invention relates to a collapsible tube in which a bellows portion forming the energy absorbing portion and a connecting portion used for connecting to another member are integrally formed by a plastic working means.

[0002]

2. Description of the Related Art A conventional collapsible tube for absorbing impact energy provided in a steering device or the like is shown in FIG.
As shown in FIG. 3, the bellows member 10 including the plurality of large-diameter portions 110 and the small-diameter portion 190, and both end portions 15 of the bellows member 10.
It was generally composed of a yoke 20 or a connecting member composed of a flange 30 or the like, which is connected to 0. The connecting members 20 and 30 and the bellows member 10 are joined by the welding means 50 at the respective terminal portions 150 and 250.

[0003]

As described above, in the conventional device, the bellows member 10 made of a thin portion and the highly rigid connecting members 20, 30 made of a cast part or a forged part are connected by the welding means 50. It is designed to be combined. That is, the two members having greatly different strength and rigidity are forcibly joined by the welding means 50. Therefore, the aggregate joined by these welding means has a discontinuity in strength and rigidity, which is not preferable as an impact energy absorber. Further, a so-called welding second occurs around the area where the welding means 50 joins, and this portion has a problem that there is a risk of deterioration in strength, particularly in repeated strength. In order to solve these problems, it is an object of the present invention to provide a collapsible tube for absorbing impact energy of an integral structure type having no welded portion between the bellows portion and the connecting portion. It is the purpose (issue).

[0004]

Means for Solving the Problems In order to solve the above problems, the present invention takes the following measures. That is, regarding the collapsible tube which is provided in a part of the steering shaft and serves to absorb impact energy applied to the steering shaft, a bellows portion including a plurality of large diameter portions and a small diameter portion, and the bellows portion. And a connecting portion continuously formed on the bellows portion, and these portions are integrally formed by a plastic working means on the basis of a thick pipe. It was decided to adopt the configuration as described above.

In addition, a method of manufacturing a collapsible tube having such a structure is based on a thick-walled hollow pipe, and a portion excluding both ends thereof is formed into a thin-walled portion by a spinning means. A step, a step of forming the thin-walled part into a bellows shape consisting of a plurality of large-diameter parts and small-diameter parts by a plastic working means such as a bulge forming means, and the both ends are left. The thick portion is formed by a plastic working means into a connecting portion used for connecting to another member.

[0006]

By adopting the above construction, the following effects are exhibited in the present invention. That is, the collapsible tube having such a structure is provided in the middle of the steering shaft as shown in FIG.
In such a state, when an impact force is applied from the steering wheel side, the collapsible tube is plastically deformed in the axial direction or the bending direction. Further, in the present invention, since the bellows portion is made of a thin member and is formed by a plastic working means such as bulge working, it is against an input load (force). The respective bellows parts are sequentially buckled and deformed, and the plastic deformation based on the buckling deformation efficiently absorbs the impact energy applied from the steering wheel side.

In particular, the collapsible tube of the present invention is
As shown in FIGS. 1 and 2, since the bellows portion and the connecting portion are integrally formed by the plastic working means,
There are no discontinuities related to strength and rigidity.
That is, the discontinuity in strength and rigidity due to the welding means unlike the conventional one does not occur. Further, since all parts are formed by the plastic working means, the direction of the flow of the material structure is constant and continuous. From these facts, the entire collapsible tube evenly shares the force (load) with respect to the impact force input to the collapsible tube, and the entire plastic deforms uniformly. As a result, input energy (impact energy)
Will be absorbed efficiently.

Further, even when the repetitive torsional force is input from the steering wheel, the joint portion between the thin bellows portion and the relatively rigid connecting portion is formed by the plastic working means. As a result, the flow of the material structure between the two is smooth, and discontinuity does not occur in terms of strength and rigidity. Therefore, fatigue strength or durability strength is increased.

Further, in the present collapsible tube having the above-mentioned structure, all parts are integrally formed by the plastic working means. Therefore, in manufacturing the collapsible tube, Thus, it becomes possible to efficiently carry out in a continuous integrated process, and it becomes possible to improve productivity.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 1 and 2, the configuration of the embodiment of the present invention is as follows: a bellows portion 1 including a plurality of sets of large-diameter portions 11 and small-diameter portions 19, and another member such as a yoke or a flange. It is basically composed of a connecting part 2 used for connecting the connecting part 2 and a transition part 5 connecting the connecting part 2 and the bellows part 1. All of these parts 1, 2 and 5 are integrally formed by plastic working means and based on a single member, for example, a metal hollow pipe or the like. .

As shown in FIG. 4, the collapsible tube having such a structure is provided in the middle of the steering shafts 91 and 92 provided between the steering wheel 99 and the steering gear device (not shown). It has become. The rotational torque from the steering wheel 99 is transmitted to the steering gear device, and the impact force from the steering wheel 99 side is dealt with by the plastic deformation of the collapsible tube. .

Next, a method of manufacturing the present collapsible tube having such a structure will be described with reference to FIG. First, in the cutting step of FIG. 3A, a relatively thick steel pipe is cut into a predetermined length, and a blank made of a hollow steel pipe is cut out. Next, FIG.
In the spinning process step (B), the central portion of the cut blank excluding both ends is plastically worked into a thin wall by a spinning working means. The thickness of the thin portion at this time is set to the thickness of the bellows portion when the bellows portion is to be formed later. Next, the thin-walled portion is formed into a bellows shape in the bellows portion forming step of FIG. The bellows forming step comprises a plastic working means such as a bulge forming means or a spinning forming means.

Next, after the bellows portion 1 is formed in this manner, the thick portion left at the end portion is used as a basis in the connecting portion forming step of FIGS. 3D and 3E. The connecting portion 2 is formed by the plastic working means. Specifically, FIG.
In step (D), the connecting portion 2 such as a yoke or a flange is continuously and integrally formed with the bellows portion 1 by a plastic working means such as an upset molding means or a press molding means. Becomes Further, when the connecting portion 2 is composed of a yoke, in the step (E) of FIG. 3, processing of the hole 25 of the yoke portion is performed at the connecting portion 2 by a flow drilling means or the like. A lining process or the like around the hole 25 is performed. By going through these series of plastic working steps, the bellows portion 1 and the connecting portion (yoke) 2, and further the transition portion 5 connecting the bellows portion 1 and the connecting portion 2 are continuously formed, and the collapsible tube is formed. Will be formed.

Next, the operation and the like of the embodiment of the present invention having these configurations will be described. That is, the collapsible tube having such a configuration is
As shown in FIG. 4, the collapsible tube is provided in the middle of the steering shaft 91, and when an impact force is applied from the steering wheel 99 side in such a state, the collapsible tube mainly undergoes plastic deformation in the axial direction. It will be plastically deformed as a whole. That is, in the present embodiment, the bellows portion 1 is made of a thin member, and a plurality of large diameter portions 11 and small diameter portions 1 are formed.
Since it is formed in combination with 9, the above-mentioned respective parts 11 and 19 are sequentially buckled and deformed with respect to the load (force) in the axial direction. Further, with respect to the load (force) in the bending direction, an appropriate portion of the bellows portion 1 is plastically deformed in the bending direction. Due to these plastic deformations, in the present embodiment, the impact energy from the steering wheel 99 is efficiently absorbed.

Particularly, in the collapsible tube of the present invention, as shown in FIGS. 1 and 2, since the bellows portion 1 and the connecting portion 2 are integrally formed by the plastic working means, There are no discontinuities related to strength and rigidity. Further, since all the parts are formed by the plastic working means, the direction of the flow of the material structure is constant and continuous. From these facts, the entire collapsible tube receives the force (load) evenly with respect to the input of the impact force, and the entire body is uniformly plastically deformed.
As a result, the input energy (impact energy) is efficiently absorbed.

Further, even when a repetitive torsional force is input from the steering wheel 99, the transitional portion 5 which is a connecting portion between the thin bellows portion 1 and the relatively rigid connecting portion 2 is provided. Since it is integrally formed by the plastic working means, the flow of the material structure between the two is smooth, and therefore, the fatigue strength and the like against the above repeated torsional input is increased. Become.

Further, in the present collapsible tube having the above-mentioned structure, all the parts are integrally formed by the plastic working means. Therefore, in manufacturing the collapsible tube, It will be possible to efficiently carry out in a continuous integrated process, and the production efficiency will be improved.

[0018]

According to the present invention, with respect to the collapsible tube which is provided on a part of the steering shaft and serves to absorb the impact energy applied to the steering shaft, at least one set of large-diameter portions is provided. And a bellows portion formed of a small diameter portion, and a connecting portion that is provided at both ends of the bellows portion and is formed continuously with the bellows portion, and each of these portions forms a thick pipe. Since the foundation is configured to be integrally formed by plastic working means, there are no discontinuities in strength and rigidity over the entire collapsible tube, and therefore, there is no impact force. , And the whole buckle deformed uniformly. As a result, the impact energy from the steering wheel can be efficiently absorbed. Moreover, since the direction of the flow of the material structure is made constant and continuous from the thin-walled bellows portion to the relatively thick-walled connection portion, it is possible to repeat from the steering wheel. The fatigue strength can be improved even when the torsion torque is input.

Further, since the collapsible tube having the above-mentioned structure is manufactured on the basis of the hollow metal pipe by the plastic working means and by the continuous integrated production system, the efficiency of material collection is improved. It has become possible to reduce the material cost. In addition, the continuous integrated production method has made it possible to improve the production efficiency, which also makes it possible to reduce the production cost.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing the overall configuration of the present invention.

FIG. 2 is a front view showing the overall configuration of the present invention.

FIG. 3 is a manufacturing process diagram showing a method of manufacturing a collapsible tube according to the present invention.

FIG. 4 is a diagram showing a state in which a collapsible tube according to the present invention is mounted on a steering device.

FIG. 5 is a developed perspective view showing the entire configuration of a conventional example.

[Explanation of symbols]

 1 Bellows part 11 Large diameter part 19 Small diameter part 2 Connection part 25 Hole 5 Transition part 91 Steering shaft 92 Steering shaft 99 Steering wheel

Claims (2)

[Claims] 1. A collapsible tube which is provided on a part of a steering shaft and serves to absorb impact energy applied to the steering shaft, wherein a bellows composed of at least one set of a large diameter portion and a small diameter portion. And a connecting part which is provided at both ends of the bellows part and which is continuously formed on the bellows part. Each of these parts is a plastic working means based on a thick pipe. A collapsible tube, which is characterized in that the collapsible tube is configured so as to be integrally formed. 2. A spinning process for forming a thin-walled portion by a spinning means on the basis of a thick-walled hollow pipe, excluding both ends thereof, and a plastic-molded portion for the thin-walled portion. The bellows part forming step of forming a bellows shape composed of a plurality of large-diameter parts and small-diameter parts by the processing means, and the thick parts left at the both ends are connected to other parts by the plastic working means. A method of manufacturing a collapsible tube, comprising: a connecting portion forming step of forming the connecting portion to be provided.