Title of Invention

A METHOD OF PRODUCING ONE-PIECE SHAFT AND YOKE MEMBER

Abstract

57) Abstract:- The present invention relates to a method of producing a one-piece shaft and yoke member comprising the steps of: (a) providing a tube including a first portion a second extending from said first portion, and a third portion extending from said second portion, said tube having a generally circular cross sectional shape and defining a first outer diameter (b) subsequent to step(a) subjecting said second and third portions of said tube to a diameter reducing process such that said second and third portions of said tube define a second outer diameter that is smaller than said first outer diameter; (c ) subsequent to step(b), subjecting said second portion of said tube to a diameter reducing process such that said second portion of said tube defines a third outer diameter that is smaller than said second outer diameter;; (d^ subsequent to step (c), forming a yoke on said portion of said tube and a splinted surface on said third portion of said tube to produce • said one-piece shaft and yoke member.

Full Text

The inventory relates to a method of producing a one-piece shaft and yoke member. In virtually every vehicle in use today, a steering system is provided for permitting a driver to control the direction of movement. A typical steering system includes a steering wheel, a steering shaft assembly and a steering device. The steering wheel is rotatably supported within a driver compartment of the vehicle for movement by a driver. The steering shaft assembly is connected at one end to the steering wheel for rotation therewith. The other end of the steering shaft assembly is connected to the steering device for turning the wheels of the vehicle in response to rotation of the steering wheel. In its simplest form, the steering shaft assembly is embodied as a single shaft or tube having a pair of yokes mounted on the ends thereof The yokes are usually connected by respective universal joints to the steering wheel and the steering device. In many vehicles, the steering shaft assembly is designed not only to provide a rotational driving connection between the steering wheel and the steering device, but also to permit relative axial movement therebetween. Such relative axial movement allows the driver of the vehicle to adjustably position the steering wheel at a desired comfortable location during use. To accomplish this, it is known to the steering shaft assembly from cooperating male and female steering shaft members. The male and female steering shaft members cooperate by means of respective external and internal splines. The telescoping splined connection provides a rotatable driving connection beeves the steering wheel and the steering device, while pennitting relative axial movement. In the past, the male steering shaft member (often referred to as the yoke shaft) was formed from an externally splined steel shaft having a steel yoke welded to the outer end thereof Similady, the female steering shaft member (often referred to as the slip yoke) was formed from a hollow steel tube having a steel yoke welded to the outer end thereof The manufacture of these well known male and female steering shaft members thus required one or more vvfelding operations and, consequently, was relatively expensive. Also, relatively extensive process conations and inspection procedures were often required to insure the integrity of the welded components. Thus, it would be desirable to provide an improved method for manufacturing a yoke shaft and a slip yoke for a vehicle steering shaft assembly which is relatively simple and inexpensive. SUMMARY OF THE INVENTION This invention relates to an improved method for faming a one-piece steering shaft member, such as an externally splined male steering shaft member (or yoke shaft) or an internally splined female steering shaft member (or slip yoke). A hollow cylindrical tube is initially provided which is preferably formed from a blank of a metallic material, such as aluminum, having an elongation factor of at least fifteen percent. It is desirable that the tube have a uniform wall thickness and define an outer diameter which is substantially uniform along the length thereof The outer diameter of one end of the tube is reduced from its original diameter. A splined surface is formed in the reduced diameter end portion ‘of the tube. The splined. surface is formed on the external surface of the yoke shaft and on the internal surface of the slip yoke. The other end of the tube is then deformed so as to provide a generally hollow rectangular cross sectional shape. This can be done in such a manner as to provide uniform wall the tube. Alternatively, a first pair of opposed sides of the hollow rectangular end of the tube may be formed having a first wall thickness, while a second pair of opposed sides may be formed having a second wall thickness different from the first wall thickness. U-shaped portions of material are next removed from Ova of the opposed sides of the hollow rectangular end of the tube. Lastly, a bore is formed through each of the yoke ears, and the square comers of the yoke ears are rounded off The finished steering shaft.member may be heat treated in a conventional manner if necessary. (a) produce said one-piece shaft and vole member. Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figs. 1 through 4, 7, and 8 are side elevational views showing various steps in a method of forming of a yoke shaft in accordance with the method of this invention. Fig. 5 is an enlarged sectional elevational view of a portion of the tube taken along the line 5-5 of Fig. 4. Fig. 6 is an enlarged sectional elevational view similar to Fig. 5 showing an alternative structure for the tube. Figs. 9 through 11, 14, and 15 are side elevational views showing various steps in a method of forming of a yoke shaft in accordance with the method of this invention. Fig. 12 is an enlarged sectional elevational view of a portion of the tube taken along the line 12-12 of Fig. 11. Fig. 13 is an enlarged sectional elevational view similar to Fig. 12 showing an alternative structure for the tube. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, there is illustrated a method for forming a one-piece steering shaft member in accordance with this invention. Figs. 1 through 8 illustrate the method in the context of the formation of an externally splined male steering shaft member (or yoke shaft), while Figs. 9 through 15 illustrate the method in the context of the connation of an internally splined female steering shaft member (or slip yoke). Each of these steering shaft members includes two ends, namely, a splined end and a yoke end. The splined end of the yoke shaft has external splines, while the splined end of the slip yoke has internal splines. The yoke ends of both the yoke shaft and the slip yoke are adapted to be connected to respective universal joints to facilitate connection to either the steering wheel or the steering device of the vehicle, as discussed above. Although the method illustiated and described herein provides for the initial connation of the splined end of the steering shaft member, followed by the subsequent connation of the yoke end of the steering shaft member, it will be appreciated that this sequence may be reversed if desired. Refining now to Figs. 1 through 8, the method of manufacturing a one-piece yoke shaft in accordance with this invention is illustrated. As shown in Fig. 1, a hollow cylindrical tube, indicated generally at 10, is initially provided. The tube 10 is preferably formed from a blank of a metallic material having an elongation factor of at least fifteen percent. For example, the tube 10 may be formed of 6061-T4 aluminum. It is desirable that the tube 10 have a uniform wall thickness and define an outer diameter which is substantially uniform along the length thereof For the purpose of illustrating the steps in the method of this invention, the tube 10 may be viewed as being divided into a first portion 11, a second portion 12, and a third portion 13, as shown by the dotted lines in Figs. 1 thermion 8 The second step in the method of this invention is to reduce the outer diameter of both the second portion 12 and the third portion 13 of the tube 10, as shown in Fig. 2. This reduction in diameter can be accomplished by any known metal funning operation, preferably feed swaging. The first portion 11 of the tube 10, however, is preferably maintained at the original first outer diameter thereof The reduced outer diameter of the second portion 12 and the third portion 13 of the tube 10 is preferably uniform and is roughly equal to the desired minor outer diameter of the splined end portion of the finished yoke shaft, as will be explained below. A tapered transition section 1 la is thus provided between the first portion 11 and the second portion 12 of the tube 10. Next, the second portion 12 of the hive 10 is subjected to a further outer diameter reducing process, as shown in Fig. 3. This further reduction in diameter can also be accomplished by any known metal forming operation, preferably recess swaging. Again, the first portion 11 of the tube 10 is preferably maintained at the original first outer diameter thereof Preferably, the wall thickness of the second portion 12 of the tube 10 remains essentially unchanged from the wall thickness of the third portion 13 of the tube. As a result, the outer diameter of the second portion 12 is smaller than the outer diameter of the third portion 13, and the outer diameter of the third portion 13 is smaller than the outer diameter of the first portion 11. The second portion 12 of the tube 10 has a uniform outer diameter and has a smooth outer surface to provide a suitable sealing surface for an elastomeric seal (not shown), such as is typically provided on a mating slip yoke, ^s will be described in further detail below. A tapered transition section 12a is thus provided between the second portion 12 and the third portion 13 of the jibe 10. Following this step, a splined surface 13a is funned in the exterior surface of the third portion 13 of the tube 10, as shown in Fig. 4. Preferably, such splined surface T3aTs formed by the third portion 13 of the tube 10 chamfered, as shown at 13 b. The first portion 11 of the tube 10 is then defomied so as to provide a generally hollow rectangular cross sectional shape. This can be done in such a manner as to provide uniform wall thicknesses for all four of the sides of the hollow rectangular first portion 11 of the tube 10, as shown in Fig. 5. However, as shown in Fig. 6, a first pair lib of opposed sides of the hollow rectangular first portion 11 of the tube 10 may be fonned having a first wall thickness, while a second pair 1 Ic of opposed sides of the hollow rectangular first portion 11 of the tube 10 may be fonned having a second wall thickness different from the first wall thickness. The connation of the fist portion 11 of the tube 10 in this manner can be accomplished by a two-step process. First, the first portion 11 of the tube 10 is initially swaged with circular dies over a mandrel having a rectangular cross sectional shape such that the interior of the first portion 11 is deformed to have the rectangular cross sectional shape, while the exterior of the first portion 11 retains the generally circular cross sectional shape. Then, the first portion 11 of the tube 10 is swaged with rectangular dies over the same mandrel such that the exterior of the first portion is deformed to have the rectangular cross sectional shape. As shown in Fig. 7, a portion of material is next removed from two of the opposed sides of the first portion 11 of the tube 10. The portions of material which are removed are preferably generally U-shaped or V-shaped, leaving respective opposed recesses 14 fonned in the opposed sides of the first portion 11 of the tube 10. The portions of material may be removed by any suitable means, such as by stamping or milling. If the wall thicknesses of the two pairs of opposed sides 1 lb and 1 Ic are different, such as shown in Fig. 6, it is preferred that the portions of material be removed from the pair of opposed sides 1 lb having the smaller wall thickness. In any event, the remaining pair of opposed sides thus define opposed yoke ears 15. Lastly, as shown in Fig. 8, a bore 16 is formed through each of the yoke ears 15, and the square comers of the yoke ears 15 are rounded off The bores 16 are co-axially aligned and may be formed by any suitable means, such as by drilling or punching. The finished yoke shaft may be heat treated in a conventional manner if necessary. Refitting now to Figs. 9 through 15, the method of manufacturing a one-piece slip yoke in accordance with this invention is illustrated. As shown in Fig. 9, a hollow cylindrical tube, indicated generally at 20, is initially provided. The tube 20 is preferably formed from a blank of a metallic material having an elongation factor of at least fifteen percent. For example, the tube 20 may be formed of 6061-T4 aluminum. It is desirable that the tube 20 have a uniform wall thickness and define an outer diameter which is substantially uniform along the length thereof For the purpose of illustrating the steps in the method of this invention, the tube 20, may be viewed as being divided into a first portion 21 and a second portion 22, as shown by the dotted lines in Figs. 9 through 15. The second step in the method of this invention is to reduce the outer diameter of the second portion 22 of tube 20, as shown in Fig. 10. This reduction in diameter can be accomplished by any known metal forming operation, preferably feed swaging. The first portion 21 of the tube 20, however, is preferably maintained at the original First outer diameter thereof. Preferably, the wall thickness of the second portiere 22 of the tube 20 remains roughly the same as its original wall thickness. The reduced outer diameter of the second portion 22 of the and is approximately equal to the desired outer diameter of the splined end portion of the finished slip yoke, as will be explained below. A tapered transition section 21a is thus provided beeves the first portion 21 and the second portion 22 of the tube 20. Next, a plurality of splines, shown in dotted lines at 22a, are formed in the interior surface of the second portion 22 of the tube 20, as shown in Fig. 11. Preferably, such splines 22a are fonned by defining the second portion 22 of the tube 20 about a splined mandrel. This can be done at the same time that the second portion 22 of the tube 20 is reduced in diameter, as described above. The inner surface of the axial end of the second portion 22 of the tube 20 may be chamfered, as shown at 22b, at the same time. The first portion 21 of the tube 20 is then defonned so as to provide a generally hollow rectangular cross sectional shape. This can be done in such a manner as to provide union wall thicknesses for all four of the sides of the hollow rectangular first portion 21 of the tube 20, as shown in Fig. 12. However, as shown in Fig. 13, a first pair 2 lb of opposed sides of the hollow rectangular first portion 21 of the tube 20 may be fonned having a first wall thickness, while a second pair 21c of opposed sides of the hollow rectangular first portion 21 of the tube 20 may be fonned having a second wall thickness different from the first wall thickness. The of the first portion 21 of the tube 20 in this manner can be accomplished in the same manner as described above with respect to the first portion 11 of the tube 10 of the yokes shaft. As shown in Fig. 14, a portion of material is next removed from two of the opposed sides of the first portion 21 of the tube 20. The portions of material which are removed are preferably generally U-shaped or V-shaped, leaving respective opposed recesses 24 fonned in the opposed sides of the first portion 21 of the tube 20. The portions of material may be removed by any suitable means, such as by stamping or milling. If the wall thicknesses of the two pairs of opposed sides 2.1b and 2lc are different, such as shown in Fig. 14, it is preferred that the portions of material be removed from the pair of opposed sides 2 lb having the smaller wall thickness. In any event, the remaining pair of opposed sides thus define opposed yoke ears 25. Lastly, as shoving in Fig. 15, a bore 26 is formed through each of the yoke ears 25, and the square comers of the yoke ears 25 are rounded off The bores 26 are co-axially aligned and may be formed by any suitable means, such as by drilling or punching. The finished slip yoke may be heat treated in a conventional manner if necessary. In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustiated in its prefered embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope. 1. A method of producing a one-piece and yoke member comprising the steps of: (a) providing a tube including a first portion, a second portion extending from said first portion, and a third portion extending from said second portion, said tube having a generally circular cross sectional shape and defining a first outer diameter; (b) subsequent to step (a), subjecting said second and third portions of said tube to a diameter reducing process such that said second and third portions of said tube define a second outer diameter that is smaller than said first outer diameter; (c) subsequent to step (b) subjecting said second portion of said tube to a diameter reducing process such that said second portion of said tube defines a third outer diameter that is smaller than said second outer diameter; (d) subsequent to step (c), forming a yoke on said first portion of said tube and a splined surface on said third portion of said tube to produce said one-piece shaft and yoke member. 2. The method as claimed in claim 1 wherein, in step (b), a tapered transition section is provided batsmen said first and second portions of said tube. 3. The method as claimed in claim 1 wherein, in step (c), a tapered transition section is provided between said second and third portions of said tube. 4. The method as claimed in claim 1 wherein said splined surface is formed on an outer surface of said third portion of said tube. 5. The method as claimed in claim 1 wherein said yoke is formed by removing . a pair of opposed portions of said first portion of said tube. 6. A method of producing a one-piece shaft and yoke member substantially as herein described with reference to the accompanying drawings.

Documents:

1545-mas-1995 abstract.jpg

1545-mas-1995 abstract.pdf

1545-mas-1995 claims.pdf

1545-mas-1995 correspondence-others.pdf

1545-mas-1995 correspondence-po.pdf

1545-mas-1995 description(complete).pdf

1545-mas-1995 drawings.pdf

1545-mas-1995 form-1.pdf

1545-mas-1995 form-26.pdf

1545-mas-1995 form-4.pdf

1545-mas-1995 others.pdf

1545-mas-1995 petition.pdf