GB2486224A

GB2486224A - Tailored Thickness Steering Tube

Info

Publication number: GB2486224A
Application number: GB1020694.4A
Authority: GB
Inventors: Steve Marley
Original assignee: EUROP TECHNICAL CT NSK
Current assignee: EUROP TECHNICAL CT NSK
Priority date: 2010-12-07
Filing date: 2010-12-07
Publication date: 2012-06-13
Anticipated expiration: 2030-12-07
Also published as: GB2486224B8; GB2486224B; DE102011086125B4; GB2486224A8; DE102011086125A1; GB201020694D0

Abstract

A method to thicken a tube a.g. a steering column may include the following steps. Firstly, providing a tube (10) having an axial length that is longer than a desired finished axial length of the tube. Secondly, inserting an object (22) inside at least a portion of a part of the tube (10), and clamping the 5 tube (10) such that the clamping holds at least a portion of the part of the tube (10) and reduces an outer diameter of at least a portion of the part of the tube (10). Thirdly, reducing the axial length of the tube (10) to the desired finished axial length of the tube (10), thereby thickening a wall of at least a portion of the part of the tube (10), the thickening 10 being radially limited by the object (22) and the clamping and axially limited by available tube material at a portion of the part of the tube (10). The tube end may be induction heated.

Description

Tailored Thickness Steering Tube The technical field of the present invention relates to a tube thickening method for a tube, especially a steering tube, a steering tube made according to such a method, and a vehicle having such a steering tube.

More particularly, the present invention relates to a method for tailoring the wall thickness of a steering tube.

For many years, attention has been given to methods for the production of steering tubes. A steering tube may form a section of a steering spindle for a vehicle and may be implemented in the form of a hollow shaft. The steering wheel is secured in place on one end of the steering tube, which with respect to the traveling direction is the rearmost. On the steering tube section, which with respect to the traveling direction is the foremost, a pinion gear may be secured for meshing into steering gearing.

A connection of a steering tube with a steering wheel may take place by means of a threaded joint. The steering tube may for this purpose comprise at its end a connection section which, starting from the end of the steering tube, comprises a substantially hollow cylindrical section and adjoining the latter a conical section which widens toward the middle of the steering tube. The hollow-cylindrical section may engage the steering wheel and has a wall thickness. This wall thickness is greater than the wall thickness required for the transfer of the torque over the remaining length of the steering tube. Conventional steering tubes may therefore have a greater wall thickness, apart from the hollow-cylindrical section, than is required. Subsequent working, in particular hammering or a like reshaping method of the tube over its entire longitudinal dimension may be necessary.

Steering tubes must comply with several different requirements to comply with safety aspects. For example, a steering tube must be able to absorb longitudinal displacements in the event of a crash. The steering tube must also be able to be adjustable within the vehicle for ergonomic reasons.

This puts constraints on manufacturing steering tubes.

While it is possible to reshape the wall thickness of a tube by hammering, a tube must nevertheless be employed as the starting product which has a greater wall thickness than would be necessary for the required torque transfer. The steering spindle part becomes thereby overall heavy or the tube must again be worked over its entire length in order to appropriately decrease the wall thickness, apart from the connection section.

In manufacturing steering tubes it is often necessary to start with a tube having a thick wall in order to process the wall tube to various thicknesses and profiles. An example may be where an internal thread is specified to secure a steering wheel to a steering shaft Efforts are made to find methods that provide a tube with a thicker wall section at an end for facilitating attachment of a steering wheel and that such methods may be carried out simply and cost effectively. It is desirable to provide a simple and cost effective tube thickening process for a tube, especially a steering tube, a steering tube made according to such a process, and a vehicle having such a steering tube. More particularly, it is desirable to provide a simple and cost effective method for tailoring the wall thickness of a steering tube.

It is desirable to increase in thickness a local area of a thin walled tube.

Attention may be given to tube manipulation with greater ease while saving time in manufacturing, raw material content weight, and cost, in the final product. It is desirable to avoid cutting the tube.

In view of the technical background discussed above, there is a need to avoid hammering or any other working of the remaining length of a tube or steering tube. This would allow work and cost savings.

It may be desirable to provide a relatively thin walled tube with a connection for securing a threaded fastener. There is a need to secure a steering wheel to a steering tube. It may be required to provide a thicker local area, such as a section or an end section, of a tube for, for example, bearing fitting or lock collar. In addition, or alternatively, it may be desirable to provide toothing when thickening a tube.

Additionally, it is desirable to avoid the cumbersome arrangements from a technical and/or economical point of view.

It is an object of the present invention to provide a tube with a thicker wall.

This object can be achieved by the features as defined in the independent claims. Further enhancements are characterized in the dependent claims.

One embodiment provides a tube thickening method for a tube, comprising the following steps: 1) providing a tube having an axial length that is longer than a desired finished axial length of the tube; 2) inserting an object inside at least a portion of a part of the tube, and clamping the tube such that the clamping holds at least a portion of the part of the tube and reduces an outer diameter of at least a portion of the part of the tube; and 3) reducing the axial length of the tube to the desired finished axial length of the tube, thereby thickening a wall of at least a portion of the part of the tube, the thickening being radially limited by the object and the clamping and axially limited by available tube material at a portion of the part of the tube. The insertion and clamping may be done in any order in step two. The reduction is made while the object of step two is inside the tube and the tube is clamped as described in step two. When step three has been made, then the tube may be released. Such a tube may be a steering tube. The end of the tube with the thickened wall may be attachable to a steering wheel. The part of the tube may be an end part of the tube where a thickening is desired.

At least the part of the tube may be malleable. Such a malleable condition of the part of the tube may be formed by a local heat source, preferably electrical induction heating.

The tube may be held by holding jaws located away from the part of the tube such that the part of the tube can be clamped, especially as described above in method step 2). The clamping and the axial reduction may shape the outside and/or the inside of at least a portion of the part of the tube.

An inner and/or an outer threading and/or toothing may be provided to the tube during the tube thickening method. For example, the inner thread and/or toothing may be provided by the object and the outer threading and/or toothing may be provided by the clamping during the tube thickening method. An inner and/or outer shape may be provided to the tube during the tube thickening method. For example, the inner and/or outer shape may have a polygonal cross section. All of these may be provided to at least a portion of a part of the tube.

The end result may be a slightly shorter tube where one end (or both if required) has had the excess length upset to create a locally thicker wall section. The excess length being the difference between the axial length of the tube of step 1) and the desired finished length of the tube after the axial reduction of step 3).

A further embodiment may provide a method for manufacturing a steering tube comprising the tube thickening method for a tube. A further embodiment may provide a steering tube made according to any one of the methods described. A further embodiment may provide a vehicle having such a steering tube.

Hereby a tube with a thicker wall section may be provided simply and cost effectively. This may also provide a simple and cost effective tube thickening method for a tube, especially a steering tube, a steering tube made according to such a method, and a vehicle having such a steering tube. Hereby cutting may be avoided. More particularly, it may provide a simple and cost effective method for tailoring the thickness of a steering tube.

Hereby a local area of a thin walled tube may be enabled to increase in thickness. This provides tube manipulation with greater ease while saving time in manufacturing, raw material content weight, and cost, in the final product.

Hereby a relatively thin walled tube with a connection for securing a threaded fastener may be provided. This may allow securing a steering wheel to a steering tube. Further, this may provide a thicker local area, such as a section or an end section, of a tube for, for example, bearing fitting or lock collar.

Hammering may hereby be avoided or any other working of the remaining length of a tube or steering tube. This would allow work and cost savings.

Additionally, cumbersome arrangements from a technical and/or economical point of view are avoided.

Other technical advantages of the present disclosure will be readily apparent to one skilled in the art from the following description and claims.

Various embodiments of the present application obtain only a subset of the advantages set forth. No one advantage is critical to the embodiments. Any claimed embodiment may be technically combined with any other claimed embodiment(s).

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred exemplary embodiments of the invention, and together with the general description given above and the detailed description of the preferred exemplary embodiments given below, serve to explain, by way of example, the principles of the invention.

FIG. I shows an exemplary tube.

FIG. 2 shows an example according to a first embodiment.

FIG. 3 shows an example according to a second embodiment.

FIG. 4 shows an example according to a third embodiment.

For clarity reasons, no hashing has been used in the drawings.

FIG. 1 discloses an example of a tube 10 that may be used when starting a tube thickening method for a tube. The tube 10 is normally hollow and has two ends. The tube 10 may have a thin wall, for example 0,5 mm to 3 mm thin wall, preferably 1,3 to 1,8 mm thin wall, that is thick enough for transferring the torque from one end of the steering tube 10 to the other.

The thin wall may be too thin for allowing a thread to be made in the thin wall or too thin for attachment of a steering wheel. The wall may have a uniform wall thickness.

As the embodiment illustrated by FIG. 1 shows, the tube 10 may have an axial length Li extending along an axial direction A of the tube 10. The axial length Li may be any suitable axial length of a steering tube 10. As explained below, the axial length Li of the tube iO is in the tube thickening method reduced to a desired finished length L3 of the tube iO that is shorter than the initial axial length Li. The finished length L3 is illustrated in FIG. 3.

During the tube thickening method of the tube 10 a part P or section P of the tube 10 may be a selected part of the tube i 0 where the tube 10 is made thicker for at least a portion of the part P. The part P may be, for example, at one end of the tube 10. The pad P may be, for example, at both ends of the tube 10 if both ends of the tube 10 are going to be provided with a thicker wall for at least a portion of the pad P. The pad P may be the pad of the tube 10 that is used for securing a steering wheel to the tube 10.

Looking along the axial direction A of the tube 10, the tube 10 may normally be circular, but any other suitable shape such as, for example, triangular, square, rectangle, or a polygonal cross section may be used.

The outer diameter of the tube 10 is indicated as D in FIG. 1. The tube 10 has a first end ii and a second end 12. A radial direction R, perpendicular to the axial direction A, of the tube 10 is illustrated in FIG. 1.

FIG. 2 illustrates an exemplary embodiment where the first end 11 of the tube 10 has been clamped with a clamp 21. The clamp 21 may be a compound die and may be comprised of a machine 20. The clamp 21 may hold at least a portion of the part P of the tube 10. The clamp 21 may be shaped such that when the tube 10 is clamped the shape of the tube is changed. In the exemplary embodiment illustrated in FIG. 2 a portion of the part P has an axial length B at the first end 11 of the tube 10 and is clamped by the clamp 21. The portion of the part P having the axial length B is reduced to a smaller tube diameter d than the tube diameter D by the clamping. Between the portion of the part P having the axial length B having the diameter d, and a section of the tube 10 having the diameter D, the diameter increases from d to D. The shape of the tube and the shape of its end section at the first end 11 may be reshaped by the shape and the clamping of the clamp 21. The clamp 21 may be used for creating a radial force El as illustrated in FIG. 2. The radial force Fl may act as a clamping force Fl holding and/or reshaping at least a portion of the part P of the tube 10.

To support the tube 10 a holding jaw 50 may be arranged. The holding jaw 50 may be a clamp or any other suitable means that supports the tube in a radial direction. In one embodiment, the holding jaw 50 may support the tube 10 along the entire axial length of the tube 10 protruding from the clamp 21. In one embodiment, the holding jaw 50 may support the tube 10 along only a portion of the axial length of the tube 10 protruding from the clamp 21. The holding jaw 10 may be positioned in any suitable location along the tube 10. One preferred location is close to or at the second end 12 of the tube 10.

As illustrated in the exemplary embodiment in FIG. 4 the holding jaw 51 may have different shapes. Holding jaw 51 may be shaped such that the holding jaw 51 supports the tube 10 in a radial direction and in an axial direction. This is achieved by the holding jaw supporting the outer surface and the end surface of the tube 10. The holding jaw 51 may have a surface that engages the tube 10 in a radial direction and another surface that engages the tube 10 in an axial direction. The holding jaw 51 may alternatively, or in addition, support the inside surface of the tube 10.

Turning to FIG. 3, an object 22, for example a plug, may be inserted into the interior of at least a portion of the part P of the tube 10. Preferably the object 22 is inserted before the clamp 21 clamps the tube 10. The object 22 has an outer surface that faces and may engage the inside of the tube 10. The object 22 may have a shape that corresponds to a desired shape to be given to the tube 10 and/or the inside of the tube 10. In FIG. 3 the object 22 has a straight smooth shape and consequently the inside of the tube 22 of a portion with the axial length C of part P will have a straight and smooth shape.

An axial force F2 may be applied to the end of the tube 10 where at least a portion of the part P of the tube 10 should be thicker, for example at the first end 11. In this respect, please see FIG. 3. The axial force F2 decreases the axial length of the tube 10 and creates a locally thicker wall 15. In FIG. 3 this is illustrated by the portion with the axial length C of part P having a thickerwall 15 then the remaining wall of the tube 10.

Turning to FiG. 4, a press means 23 may be used for creating the axial force F2 illustrated in FIG. 3. A force F3 may be used to act upon the press means 23. The force F2 may be created directly on the tube 10 or indirectly by use of other means. The axial force F2 may press the tube shorter. The end result is a slightly shorter tube where one end, or both if required, has had the excess length upset to create a locally thicker wall part.

With reference to FIG. I to FIG. 3, the initial axial length LI may be reduced or extended to an axial length L2. The axial length L2 is a result of the tube 10 with the initial length Li being clamped. By this clamping the initial length Li may be reduced or extended. The finished axial length L3 of the tube iO is shorter than the axial length Li that the tube 10 had initially. The application of an axial force to one end, or both if required, causes to upset the axial length Li to create a locally thicker wall part and the tube 10 to have the axial length L3. The part P of the tube 10 may be any part or section of the tube 10, but would in the example of a steering tube be a part P starting from an end ii of the tube 10 stretching a distance towards the other end i 2 of the tube 10. The distance may vary, but is normally at least the axial length necessary for attaching a steering wheel and/or the axial length of the clamp 2i.

With reference to FIG. 2 and 3, the part P comprises an exemplary portion with the axial length B of part P and an exemplary portion with the axial length C of part P. The axial length B is reduced to the axial length C when the tube 10 is pressed shorter. In one embodiment, the clamp 21 shapes the portion with the axial length B of part P of the tube 10. This length B is then subsequently pressed shorter, creating a locally thicker wall section over the length C. A portion of the part P of the tube 10 that undergoes deformation may be made malleable. For example, by using heat a part of the tube 10 may be made sufficiently malleable for tailoring the thickness of the tube 10. In one embodiment, a localised heat source may be applied to the tube 10, for example, by use of electrical induction heating. For example a heating element 25 may be comprised by the clamp 21. Alternatively, or in addition, a heating element 26 may be comprised by the object 22.

Alternatively, or in addition, a heating element 27 may be comprised by the press means 23.

One exemplary embodiment discloses a method for tailoring a wall thickness of a tube. For example, an embodiment may disclose a method for tailoring the thickness of a steering tube. Such a method may for example comprise the following steps: 1) providing a tube 10 having an axial length Li that is longer than a desired finished axial length L3 of the tube 10 of the tube thickening process; 2) in any order, inserting an object 22, for example a plug, inside at least a first portion of a part P of the tube 10 at one end ii, and clamping the tube such that the clamping holds at least a second portion of the part P of the tube 10 and reduces an outer diameter D of at least a third portion of the part of the tube 10; and 3) reducing the axial length of the tube 10 to the desired finished axial length L3 of the tube 10, thereby thickening a wall 15 of at least a fourth portion of the part P the tube 10, the thickening being radially limited by object 22 and the clamping by the clamp 21 and axially limited by available tube material at a fifth portion of the part P of the tube 10. These steps may be used for one or for both of the ends of the tube 10. The first to fifth portions of the part P may or may not be equal.

Various additional steps may be made to this exemplary method outlined above. The following gives a more detailed disclosure of a tube thickening process with various exemplary additional steps.

In an exemplary embodiment, the starting length LI of a tube 10, for example a steering tube, is longer than the finished length L3. The tube is pressed shorter to the finished length L3, thereby thickening a portion of a wall of the tube 10 along the length C. For example, the force F2 may be applied to the first end 11 of the tube 10 and a part of a wall of the tube 10 may thereby be thickened.

In an exemplary embodiment, a tube 10 is placed into holding jaws 50, 51 of a purpose-made machine. A length of the tube 10 protrudes beyond the clamping jaws 50, 51. The protruding length is either sufficiently malleable for the thickening process or is made so by application of a localised heat source 25, 26, 27, for example by using electric induction heating. A compound die 21 may be pressed over the protruding tube 10.

Preferably an end section not held by the clamping jaws 50, 51 is held by the compound die 21. The compound die may hold the tube 10 or may clamp or press the tube 10 shaping the engaged end section, for example by reducing the diameter of the tube 10. The clamping jaws 50, 51 may engage the tube 10 over the entire length not clamped by the clamp 21, or a portion of that length.

The construction of the die 21 may maintain the outside diameter of the tube 10. The use of an object 22 within the die 21 allows the internal diameter of the tube 10 to be reduced as the tube 10 is pressed shorter.

The end result of the method may be a slightly shorter tube 10, compared with the tube's initial length, where one end (or both if required) has had the excess length upset to create a locally thicker wall section 15. The excess length may be L1-L3. According to one embodiment, the tube 10 is a steering tube and the end of the tube 10 is attached to a steering wheel.

According to one embodiment, at least the end section of the tube 10 is malleable; preferably the malleable condition is formed by a local heat source, preferably electrical induction heating.

The tube 10 may be held by holding jaws 50, 51 located away from the end section such that at least a portion of the part P of the tube 10 can be clamped as in method step 2) described above. In one embodiment, the clamping and the axial reduction shape the outside of the end section of the tube 10. Alternatively, or in addition, the object 22 and the axial reduction shape the inside of at least a portion of the part of the tube 10.

In one embodiment, a method may include the clamping and the axial reduction to shape the outside and/or the inside of at least a portion of the part P of the tube 10. In one embodiment, a method may include that an inner and/or an outer threading and/or toothing is provided to the tube 10 during the tube thickening process. For example, the inner thread and/or toothing may be provided by the object 22 and the outer threading and/or toothing may be provided by the clamping during the tube thickening process. According to one embodiment, the method may include that an inner and/or outer shape is provided to the tube 10 or at least a portion of the part P of the tube 10. For example, such an inner and/or outer shape may have a polygonal cross section. In one embodiment the tube thickening process may provide a tube where the thicker part is round on the outside and has a polygonal cross section on the inside. For example, such a tube could be engaged with a connection having a polygonal cross section.

According to one embodiment, a steering tube may be manufactured using any combination of the described method and/or steps above. A steering tube may be made according to any one of the described method and/or steps above. A vehicle may comprise such a steering tube.

The method and product discussed above tailors the thickness of tubes.

The invention, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein.

While the invention has been described and is defined by reference to particular preferred embodiments of the invention, such references do not imply a limitation on the invention, and no such limitation is to be inferred.

The invention is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those ordinarily skilled in the pertinent arts. The described preferred embodiments of the invention are exemplary only, and are not exhaustive of the scope of the invention.

Any described or claimed embodiments can be combined with any other described or claimed embodiments. Consequently, the invention is intended to be limited only by the scope of the appended claims, giving full cognizance to equivalents in all respects.

Claims

Claims: I A tube thickening method, comprising the following steps: 1) providing a tube (10) having an axial length Li that is longer than a desired finished axial length L3 of the tube; 2) inserting an object (22) inside at least a portion of a part P of the tube (10), and clamping the tube (10) such that the clamping holds at least a portion of the part P of the tube (10) and reduces an outer diameter D of at least a portion of the part P of the tube (10); and 3) reducing the axial length of the tube (10) to the desired finished axial length L3 of the tube (10), thereby thickening a wall (15) of at least a portion of the part P of the tube (10), the thickening being radially limited by the object (22) and the clamping and axially limited by available tube material at a portion of the part P of the tube (10).
2 The method according to claim 1, wherein the tube (10) is a steering tube and an end (11) of the tube with the thickened wall is attachable to a steering wheel.
3 The method according to claim 1 or 2, wherein at least the part P of the tube (10) is malleable.
4 The method according to claim 3, wherein the malleable condition is formed by a local heat source (25), (26), (27), preferably electrical induction heating.
The method according to any one of the preceding claims, wherein the tube (10) is held by holding jaws (50), (51) located away from the part P of the tube (10) such that the part P of the tube (10) can be clamped as claimed in method step 2).
6 The method according to any one of the preceding claims, wherein the clamping and the axial reduction shape the outside of at least a portion of the part P of the tube (10).
7 The method according to any one of the preceding claims, wherein the object (22) and the axial reduction shape the inside of at least a portion of the part P of the tube (10).
8 The method according to any one of the preceding claims, wherein the end result is a slightly shorter tube (10) where one end, or both if required, has had the excess length upset to create a locally thicker wall section (15).
9 The method according to any one of the preceding claims, further comprising providing an inner and/or an outer threading and/or toothing to at least a portion of the part P of the tube (10)! The method according to claim 9, wherein the inner thread and/or toothing is provided by the object (22) and the outer threading and/or toothing is provided by the clamping during the tube thickening method.11 The method according to any one of the preceding claims, further comprising providing an inner and/or outer shape to at least a portion of the part P of the tube (10).12 The method according to claim 11, wherein the inner and/or outer shape has a polygonal cross section.13 A method for manufacturing a steering tube comprising the method in any one of the preceding claims.14 A steering tube made according to any one of the preceding claims.A vehicle having a steering tube according to claim 14.16 A steering tube as substantially described herein.17 A method as substantially described herein.AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWSI A tube thickening method, comprising the following steps: 1) providing a tube (10) having an axial length Li that is longer than a desired finished axial length L3 of the tube; 2) inserting an object (22) inside at least a portion of a part P of the tube (10), and clamping the tube (10) such that the clamping holds at least a portion of the part P of the tube (10) and reduces an outer diameter D of at least a portion of the part P of the tube (10); and 3) reducing the axial length of the tube (10) to the desired finished axial length L3 of the tube (10), thereby thickening a wall (15) of at least a portion of the part P of the tube (10), the thickening being radially limited by the object (22) and the clamping and axially limited by available tube material at a portion of the part P of the tube (10); wherein the tube (10) is a steering tube and an end (11) of the tube with the thickened wall is attachable to a steering wheel. r2 The method according to claim 1, wherein at least the part P of the tube (10) is malleable.3 The method according to claim 2, wherein the malleable condition is formed by a local heat source (25), (26), (27).4 The method according to claim 3, wherein the local heat source (25), (26), (27) comprises electrical induction heating.The method according to any one of the preceding claims, wherein the tube (10) is held by holding jaws (50), (51) located away from the part P of the tube (10) such that the part P of the tube (10) can be clamped as claimed in method step 2).6 The method according to any one of the preceding claims, wherein the clamping and the axial reduction shape the outside of at least a portion of the part P of the tube (10).7 The method according to any one of the preceding claims, wherein the object (22) and the axial reduction shape the inside of at least a portion of the part P of the tube (10).8 The method according to any one of the preceding claims, wherein the end result is a slightly shorter tube (10) where one end, or both if required, has had the excess length upset to create a locally thicker wall section (15).9 The method according to any one of the preceding claims, further comprising providing an inner and/or an outer threading and/or toothing to at least a portion of the part P of the tube (10).The method according to claim 9, wherein the inner thread and/or toothing is provided by the object (22) and the outer threading and/or toothing is provided by the clamping during the tube thickening method.11 The method according to any one of the preceding claims, further comprising providing an inner and/or outer shape to at least a portion of the part P of the tube (10).12 The method according to claim 11, wherein the inner and/or outer shape has a polygonal cross section.13 A method for manufacturing a steering tube comprising the method in any one of the preceding claims.14 A steering tube made according to any one of the preceding claims.A vehicle having a steering tube according to claim 14.16 A steering tube as substantially described herein.17 A method as substantially described herein. r r