Method for producing an outer shell for overrunning clutches

A novel method for producing an outer shell for an unitary overrunning roller clutch and roller bearing having a central section provided with camming or ramp surfaces about its circumference and on either side thereof a smooth cylindrical end section as a race for cylindrical rollers with the diameter of the inner enveloping circle of the central section being less in the area of the camming surfaces than the diameter of the end sections comprising forming a shell of sheet metal, inserting into the shell a molding punch whose outer contour corresponds to the desired inner contour of the outer shell, stretching the shell to its final outer diameter with a die moving relative to the punch whereby the shell tightly grips the molding punch and pulling the molding punch out of the shell which will elastically widen.

STATE OF THE ART 
Outer shells of this type for overrunning clutches and roller bearings are 
known and the diameter of the inner enveloping circuit should be less than 
the diameter of the adjacent races so that a cage arranged in the central 
region with camming surfaces and accommodating the camming rollers can be 
secured against rotation in a simple manner by engaging the camming 
surfaces. The fact that both races on either side of the central section 
must have a larger diameter causes manufacturing problems. 
In a known shell of this type, these difficulties have been avoided in U.S. 
Pat. No. 3,194,368 so that only one race had a diameter larger than the 
inner enveloping circle in the gripping range, while the second race has a 
smaller diameter. However, this has the result that the two races with 
different diameters must be given rollers with different diameters which 
involves higher production costs and the risk of mixups. The manufacture 
of such a shell by cutting or machining would present no problems. But 
such a process is out of the question for cost reasons. 
OBJECTS OF THE INVENTION 
It is an object of the invention to provide a non-cutting method of 
producing an outer shell for an overrunning clutch and roller bearing in a 
simple economical manner. 
This and other objects and advantages of the invention will become obvious 
from the following detailed description. 
THE INVENTION 
The novel method of the invention for producing an outer shell for an 
unitary overrunning roller clutch and roller bearing having a central 
section provided with camming or ramp surfaces about its circumference and 
on either side thereof a smooth cylindrical end section as a race for 
cylindrical rollers with the diameter of the inner enveloping circle of 
the central section being less in the area of the camming sufaces than the 
diameter of the end sections comprises forming a shell of sheet metal, 
inserting into the shell a molding punch whose outer contour corresponds 
to the desired inner contour of the outer shell, stretching the shell to 
its final outer diameter with a die moving relative to the punch whereby 
the shell tightly grips the molding punch and pulling the molding punch 
out of the shell which will elastically widen. 
The starting shell may be preformed in a known manner such as by deep 
drawing sheet metal. A manufacturing method of this type has not been 
suggested before since it was believed that the shell molded with the 
depressions of the molding punch in the area of the camming surfaces could 
not be removed from the molding punch without destruction thereof or 
harmful deformations. However, it has been found that the method is 
successful and the deformations required to remove the molding punch are 
within the elastic range of the shell material if care is taken that the 
projections in the area of the camming surfaces do not exceed a certain 
extent. These projections can be controlled by the design since the 
dimensions of the molded camming surfaces can be kept very small. 
The stripping of the finished shell from the molding punch can be effected 
in a simple manner by the die itself during its return movement relative 
to the punch.

The process will now be described by reference to the drawings. First, a 
cylindrical shell 1 is produced, e.g. by deep drawing, which has a closed 
bottom 2. Then, a circular hole 3 is provided in the bottom 2 (FIG. 2) 
whose diameter is smaller than the bore diameter of the cylindrical shell 
1, so that an edge or rim 4 remains at this end. The preshaped shell 1 is 
then placed on a molding punch 5 as shown in FIG. 3 which consists of 
punch shaft 6 which is followed by a smooth cylindrical race region 7 
which is joined by a central region 8 which is provided with recesses for 
the formation of the camming surfaces and which is finally followed by a 
smooth cylindrical race region 9 which has the same diameter as the region 
7. At the end of the molding punch 5 is finally provided a region 10 which 
is selected in its diameter so that it can engage the hole 3 on the bottom 
of shell 1. 
A die 11, which moves relative to the punch 5, acts with its bore on the 
outer shell of the shell 1 and stretches the latter with the result shown 
in FIG. 4. The die 11 has been brought from its top position shown in FIG. 
3 into the bottom position shown in FIG. 4, and has effected the necessary 
deformation on shell 1. When the die 11 is moved from the bottom position 
shown in FIG. 4 into its upper starting position, it will strip off at the 
same time the finish-molded shell 1 from the molding punch 5, with the 
shell 1 being elastically widened in the range of its camming surfaces so 
that it can be removed from the top over the region 9 of the molding 
punch. 
Various modifications of the process of the invention may be made without 
departing from the spirit or scope thereof and it should be understood 
that the invention is to be limited only as defined in the appended claims 
.