Metal deforming – Process – Tube making or reshaping
Reexamination Certificate
2000-08-22
2001-07-10
Tolan, Ed (Department: 3725)
Metal deforming
Process
Tube making or reshaping
C072S370100, C072S370230, C029S888090
Reexamination Certificate
active
06257041
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates in general to vehicular steering shaft assemblies and in particular to a method of manufacturing a one-piece steering shaft 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 for manufacturer build tolerance, installation, and relative body movement. To accomplish this, it is known to construct 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 between the steering wheel and the steering device, while permitting 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. Similarly, 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 welding operations and, consequently, was relatively expensive. Also, relatively extensive process controls 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 forming 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 relative to the opposite end. 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.
A yoke member is then formed in the opposite end of the tube. In one embodiment, the opposite end of the tube is first 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 thicknesses for all four of the sides of the hollow rectangular end of 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 then removed from two of the opposed sides of the hollow rectangular end of the tube to form a pair of opposed yoke cars.
In a second embodiment, the opposite end is maintained in its original hollow cylindrical shape and is machined to form the opposed yoke arms of the yoke member. In a third embodiment, a hollow tube is provided having a diameter which is uniform along the length thereof. The outer diameter of the entire tube is reduced a predetermined amount and the outer diameter of a portion of the tube, including one end, is further reduced an additional predetermined amount. In this third embodiment, the splined surface is formed in the end which has been reduced the additional amount while the yoke member is formed in the less reduced, opposite end.
In all embodiments, a bore is stamped, drilled, or otherwise formed through each of the yoke ears. The square corners of the yoke ears may be rounded off in the step where the yoke member is initially formed or in a subsequent step. In addition, the finished steering shaft member may be heat treated in a conventional manner if necessary.
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.
REFERENCES:
patent: 2227436 (1941-01-01), Buckwalter
patent: 3486349 (1969-12-01), Ritsema
patent: 3566651 (1971-03-01), Tlaker
patent: 3804467 (1974-04-01), Austermann
patent: 4095450 (1978-06-01), Opland et al.
patent: 4213351 (1980-07-01), Rowlinson
patent: 4601215 (1986-07-01), Barnabe et al.
patent: 4602520 (1986-07-01), Nishikawa et al.
patent: 4738154 (1988-04-01), Hancock
patent: 4781054 (1988-11-01), Brown et al.
patent: 4833936 (1989-05-01), Mariani et al.
patent: 5464251 (1995-11-01), Castellon
patent: 5771737 (1998-06-01), Yaegashi
patent: 5836823 (1998-11-01), Shellaberger
patent: 6038901 (2000-03-01), Stein et al.
patent: 33 35 912 A1 (1985-04-01), None
patent: 0 612 649 (1994-08-01), None
patent: 2 679 860 (1993-02-01), None
patent: 2 091 141 (1982-07-01), None
patent: 59-24547 (1984-02-01), None
patent: 61-166769 (1986-07-01), None
patent: 6-39473 (1994-02-01), None
MacMillan Sobanski & Todd LLC
Spicer Driveshaft, Inc.
Tolan Ed
LandOfFree
Method of forming a one-piece steering shaft member does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of forming a one-piece steering shaft member, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of forming a one-piece steering shaft member will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2542974