Ball pin of a universal joint for motor vehicles

A metallic ball pin of a universal joint, preferably one with high load-bearing capacity, for motor vehicles, which is mounted movably in all directions in a bearing shell of a housing with a joint ball 2 designed at one end of a pin stump 1. To improve its functional properties and to reduce its manufacturing costs, a machined joint ball 2 with a through-hole 5 is nonrotatably attached to a fastening pin 4 of a pin stump 1 manufactured by cold forming in the direction of the longitudinal axis of the pin stump 1, and it is held by deforming the fastening pin 4.

FIELD OF THE INVENTION 
The present invention pertains to a ball pin of a universal joint, 
preferably one with high load-bearing capacity, for motor vehicles which 
is mounted movably in all directions in a bearing shell of a housing with 
a joint ball provided at one end of a pin stump. 
BACKGROUND OF THE INVENTION 
A ball pin with these design features corresponds to the state of the art 
as put into practice in universal joints with high load-bearing capacity 
in chassis of motor vehicles. Such a ball pin has been manufactured in 
very large numbers by the corresponding manufacturers during the past 
decades. They are manufactured in one piece by machining an optionally 
preformed blank. Thus, different pin sizes require different blanks and 
correspondingly different machine control programs for machining in series 
production. The notch effect on the surface of the neck of the pin stump 
at its undercut transition into the joint ball, which is generated by the 
machining, causes a special problem, because the permanent load-bearing 
capacity is considerably reduced as a result. It is also difficult to meet 
high requirements in terms of corrosion protection, especially at the neck 
of the pin stump, at its transition into the joint ball. This corrosion 
protection is partially ensured by a very expensive process in the 
prior-art ball pins, of which millions of pieces are manufactured. 
French Patent No. FR-PS 1,089,717 discloses a universal joint designed for 
a special application, in which the joint ball with an inner cone of a 
through-hole is axially pressed onto an outer cone of a fastening pin on a 
pin stump by a threaded screw. A very similar connection of a joint ball 
to a pin stump has also been known from British Patent No. GB-PS 1,020,671 
for a joint of a relatively large size. Such ball pin designs are 
expensive and are equally poorly suitable for large lots for use in 
heavily loaded ball joints as for the transmission of stronger rotating 
forces between the joint ball and the pin stump. 
The fastening of a joint ball made of plastic on a cylindrically designed 
ball pin made of steel for ball joints or the like carrying low loads has 
been known from German Auslegeschrift No. DE-AS 11,05,292. German Utility 
Patent No. DE-GM 17,08,040 discloses a mounting of spherical control pins, 
in which a spherical head part is prepared separately from a hard 
material, and it is attached to a pin made of a tough, elastic material 
with a blind hole. 
SUMMARY AND OBJECTS OF THE INVENTION 
It is an object of the present invention is to provide a ball pin design 
for ball joints with high load-bearing capacity in the chassis of a motor 
vehicle, which can be manufactured according to modern manufacturing 
methods at low cost for large lot sizes and which makes possible a high 
level of adaptation to different ball joint sizes. 
According to the invention, a metallic ball pin is provided for use in a 
universal joint for motor vehicles. The ball pin is mounted for movement 
in all directions, within a bearing shell. The bearing shell is within a 
housing. The joint ball of the ball pin is designed provided at one end of 
a pin stump. The joint ball is machined with a through hole which is 
non-rotatably attached to a fastening pin of the pin stump. The pin stump 
is prepared by cold forming in a direction of a longitudinal axis of the 
pin stump. The pin stump is held by deformation of the fastening pin. The 
joint ball has a machined surface. The joint ball is non-rotatably 
attached to the pin stump and is fastened to the pin stump by cold forming 
a flanged edge at the end of the fastening pin. The through hole of the 
joint ball and the fastening pin of the pin stump have complimentarily 
engaging cross-sections and cylindrical jacket surfaces. The fastening pin 
and the through hole of the joint ball may be provided with support 
flanges acting in the axial direction of the pin stump and the flanged 
edge at the end of the fastening pin is in the form of a beaded edge 
connecting the joint ball to the fastening pin. The beaded edge may be 
located within the through hole of the joint ball. 
Such a design of the ball pin makes it possible to combine uniformly 
designed joint balls and different pin stumps with one another in order to 
build up a modular system. This achieves the result that manufacturing 
costs can be considerably reduced. By connecting the joint ball to a pin 
stump manufactured by cold forming, notch effects on the surface of the 
ball pin are avoided. An extrusion process for cold forming is preferably 
used to manufacture the pin stump, so that surfaces of very high quality 
are formed, and the strength of the pin stump will be higher than in the 
case of prior-art pin stumps which are provided by machining. This leads 
to considerable functional improvements and to an increase in permanent 
load-bearing capacity. The strength-increasing properties of a extrusion 
process are utilized for preparing the pin stump. The deformation of the 
fastening pin for connecting the joint ball to the pin stump ensure a 
secure connection between these two parts even without conical fitting 
surfaces, which would require a special processing. The through-hole of 
the joint ball and the fastening pin of the pin stump thus having 
complementary, mutually engaging cross sections, but cylindrical jacket 
surfaces. Processing of the pin stump manufactured by cold forming is not 
necessary. Corrosion protection meeting high requirements can be achieved 
with simple means. 
The various features of novelty which characterize the invention are 
pointed out with particularity in the claims annexed to and forming a part 
of this disclosure. For a better understanding of the invention, its 
operating advantages and specific objects attained by its uses, reference 
is made to the accompanying drawings and descriptive matter in which 
preferred embodiments of the invention are illustrated.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The ball pin according to the exemplary embodiment in FIG. 1 is comprised 
of a pin stump 1 and a joint ball 2, both of which are manufactured 
independently from one another and are then permanently connected to one 
another. The pin stump 1 can be inserted with an outer cone 3 into a 
corresponding inner cone of a motor vehicle part. The joint ball 2 is 
inserted with a bearing shell into the housing of a universal joint, which 
can be connected to another motor vehicle part. 
At an axial end, the pin stump 1 has a fastening pin 4, to which the joint 
ball 2 with a cylindrical through-hole 5 is nonrotatably attached. A 
flanged edge 6, which is provided at the free end of the fastening pin 4 
and is flanged to the outside after the joint ball 2 has been attached to 
the fastening pin 4, is used to connect the joint ball 2 to the fastening 
pin 4. The nonrotatable seating of the joint ball 2 on the fastening pin 4 
is achieved by the fastening pin 4 and the through-hole 5 of the joint 
ball 2 having complementarily engaging cross-sectional profiles. For 
example, longitudinally extending wedges or ribs 11 are provided for this 
purpose. A slightly conical design of the fastening pin 4 and of the 
through-hole 5 for special applications shall not be ruled out, either. 
A joint ball 2 of preferably constant dimensions, with corresponding 
processing and treated ball surface 7 is nonrotatably placed on the pin 
stump 1. The treatment of the surface 7 preferably is in the form of a 
machining. The pin stump is manufactured with accurate fit according to 
the cold extrusion process, in adaptation to special applications. 
Constant ball dimensions make it possible to considerably reduce the 
expense of machining and to improve the quality of the joint ball 2. Means 
for corrosion protection may be applied by simple means especially to the 
neck 8 of the pin stump 1 prior to the mounting of the joint ball 2, and 
this corrosion protection is improved compared with prior-art ball pins 
especially in the groove between the joint ball surface 7 and the neck 8 
of the pin stump 1. Both the joint ball 2 and the pin stump 1 consist of a 
metallic material and are therefore particularly suitable for universal 
joints with high load-bearing capacity. 
In the exemplary embodiment according to FIG. 2, the flanged edge 6 of the 
fastening pin 4 is displaced into the inside of the joint ball 2 to reduce 
the overall height of the joint. Support flanges 9 spaced from ends of the 
through-hole 5 and acting in the axial direction of the pin stump, or 
designs with a comparable action, are provided on the inner jacket of the 
through-hole 5 of the joint ball 2 and on the outer jacket of the 
fastening pin 4. 
FIG. 3 shows a design of the pin stump 1 and of the fastening pin 4, which 
are modified compared with the representation in FIG. 1, wherein the 
fastening pin 4 has, e.g., a noncircular cross-sectional profile 12 and is 
inserted into a complementary profile (rectangular square, triangular, 
rhombic, trapezoidal, polygonal, etc.) of the joint ball and fastened, 
e.g., shrunk in. The pin stump 1 also has a circular fastening groove 10 
for one end of a sealing bellows arranged between the housing of a 
universal joint and the ball pin. 
While specific embodiments of the invention have been shown and described 
in detail to illustrate the application of the principles of the 
invention, it will be understood that the invention may be embodied 
otherwise without departing from such principles. 
APPENDIX 
______________________________________ 
LIST OF REFERENCE NUMERALS: 
______________________________________ 
1 Pin stump 
2 Joint ball 
3 Outer cone 
4 Fastening pin 
5 Through-hole 
6 Flanged edge 
7 Ball surface 
8 Pin neck 
9 Support flange 
10 Fastening groove 
11 Wedges or ribs 
12 Non circular cross section 
______________________________________