The invention relates to a wheel-body forming apparatus which is capable of forming up a high-precision wheel body having the perfect roundness, more partiuclarly, to an apparatus used for forming any of those wheel bodies such as the inner-and-outer races or pillow of bearing, or automotive gauges or sleeves for example, by applying a rolling process before eventually forming the objective material into the predetermined configuration. The apparatus related to the invention is mainly comprised of three rotative members including a shape-forming roller, a mandrel, and a supporting roller, which are respectively installed on a plane in parallel with each other. Of these, the shape-forming roller and the supporting roller are independently driven, and yet, the apparatus related to the invention is further comprised of means for numerically controlling the number of the rotation of the supporting roller relative to the number of the rotation of the shape-forming roller in accordance with the variation of the diameter of the wheel body being formed.

SUMMARY OF THE INVENTION 
The present invention relates to an apparatus made available for forming 
any of those wheel bodies such as the inner-and-outer races or pillow of 
bearing, or automotive gauges or sleeves for example, by applying a cold 
rolling process before eventually forming the objective material into the 
predetermined configuration. The apparatus related to the invention is 
mainly comprised of three rotative members including a shape-forming 
roller, a mandrel, and a supporting roller, which are respectively 
installed on a plane in parallel with each other. Of these, both the 
shape-forming roller and the supporting roller are independently driven, 
and yet, the apparatus related to the invention is further comprised of 
means for numerically controlling the number of the rotation of the 
support roller relative to the number of the rotation of the shape-forming 
roller in accordance with the variation of the diameter of the wheel body 
being formed up. 
BACKGROUND OF THE INVENTION 
There are a variety of wheel-body forming apparatuses proposed by the prior 
arts including the one disclosed in the U.S. Pat. No. 3,803,890. This 
prior art proposes an apparatus which forms a wheel body by applying 
rolling process using specific constituents including four rollers which 
are respectively set to four positions on the external circumferential 
surface of a work making up the wheel body to be processed through the 
mandrel in the center of these rotative members to allow the objective 
work to be held in position in the manner of freely rotating itself while 
allowing the shape-forming roller to press itself against another roller 
before eventually forming up a complete wheel body. However, the 
above-cited wheel-body forming apparatus is not provided with any member 
corresponding to the supporting roller securely holding the mandrel. This 
not only causes the strength of the mandrel to lower itself when the 
rolling process is underway, but the apparatus itself needs to 
independently provide complex mechanism for stably rotating the mandrel. 
Furthermore, since the above-cited wheel-body forming apparatus needs to 
correctly regulate four positions of the external circumferential surface 
of the work by delicately operating four rollers, the work piece cannot 
fully be extended itself in the direction of the diameter, thus eventually 
resulting in the poor rolling efficiency, while making it difficult for 
the apparatus cited above to make up a work having the perfect roundness. 
OBJECT OF THE INVENTION 
The primary object of the invention is to overcome those problems mentioned 
above by providing a novel wheel-body forming apparatus which is capable 
of precisely processing a work piece into the one having the perfect 
roundness by independently driving the shape-forming roller and the 
supporting roller to provide the work piece with a specific rotation 
torque by means of the shape-forming roller and the mandrel by causing the 
supporting roller to rotate itself in accordance with the variation of the 
diameter of the work piece and the rotation of the shape-forming roller. 
Another object of the invention is to provide a novel wheel-body forming 
apparatus which is capable of securely improving the durability of the 
mandrel by dispensing with slip normally occurring between the mandrel and 
the supporting roller by virtue of the independent driving of the 
shape-forming roller and the supporting roller. 
Another object of the invention is to provide a novel wheel-body forming 
apparatus which is capable of easily controlling the number of the 
rotation of AC motors by merely installing an inverter between the 
power-supply source and the AC motors without using complex means for 
controlling the number of the rotation of the AC motors. 
Another object of the invention is to provide a novel wheel-body forming 
apparatus which is provided with the extremely simplified constitution by 
allowing a belt to slip itself during the initial stage of the wheel-body 
forming process and capable of securely preventing over-current from 
flowing through AC motors by virtue of the slipping movement of the belt. 
Another object of the invention is to provide a novel wheel-body forming 
apparatus which is capable of generating the predetermined rotation torque 
by applying a compact and light-weight oil-pressure motor and easily 
preventing the oil-pressure motor from incurring mechanical damage by 
virtue of providing the oil-pressure motor with a relief valve. 
A still further object of the invention is to provide a novel wheel-body 
forming apparatus which is capable of precisely controlling the rotations 
of the rotative members by applying numerical control means event when 
either the mandrel or other rollers are worn out or while processing other 
kinds of work pieces. 
Those objects mentioned above and further objects of the invention will be 
better understood from the following detailed description of the preferred 
embodiments in reference to the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now more particularly to the accompanying drawings, preferred 
embodiments of the wheel-body forming apparatus related to the invention 
are described below. 
(The First Preferred Embodiment) 
FIG. 1 is the schematic diagram of the first preferred embodiment of the 
wheel-body forming apparatus related to the invention. -shaped movable 
frame 3 having a rotative shape-forming roller 4 is installed to the tip 
end of piston rod 2 of the pressure cylinder 1. The shape-forming roller 4 
is provided with the wheel-body forming portion 4a in the center of the 
external circumferential surface and the regulation surfaces 4b/4b on the 
both-side circumferential surfaces. Mandrel 5 which comes into contact 
with and leaves the shape-forming roller 4 is installed in order that it 
can travel itself in the arrowed direction b crossing the arrowed 
direction a, i.e., in the direction of the reciprocation of the piston rod 
2, at right angle. In conjunction with wheel-body shape-forming portion 4a 
of the shape-forming roller 4, mandrel 5 is provided with wheel-body 
shape-forming portion 5a in the center of the external circumference and 
regulation surfaces 5b/5b on the both-side circumferential surfaces. An 
end of shaft 5c of mandrel 5 is installed to friction block 7 via metal 6 
in order that the shaft end 5c can rotate itself. Piston rod 9 of cylinder 
8 used for shifting the position of the mandrel 5 is connected to the 
friction block 7. The surface of shaft end 5c of the mandrel 5 is secured 
to the back plate 11 with bolt 10. Mandrel 5 can optionally be replaced 
with the new one by removing bolt 10. Rotative supporting roller 13 is 
installed to -shaped stationary frame 12. The support roller 13 is 
provided with contact surfaces 13a/13a in specific positions opposite from 
the regulation surfaces 4b/4b of the shape-forming roller 4. These contact 
surfaces 13a/13a respectively face the regulation surfaces 5b/5b on the 
back of the mandrel 5. The work piece 14 which is substantially the 
ring-shaped material for making up a wheel body is processed by applying a 
cold rolling process between the wheel-body shape-forming portion 4a of 
the shape-forming roller 4 and the wheel-body shape-forming portion 5a of 
the mandrel 5. 
These rotative members including the shape-forming roller 4, mandrel 5, and 
the supporting roller 13 are respectively installed on the plane surface 
in parallel with each other as shown in FIG. 2, while these rotative 
members are respectively held by shaft means. Telescopic connecting shaft 
16 having ball joints 15/15 on both sides is coupled to the shape-forming 
roller 4, while an ed of this shaft 16 is coupled to sprocket shaft 17 
which is connected to input sprocket 18. The rotating shaft 20 of the 
first motor 19 independently driving the shape-forming roller 4 is coupled 
to output sprocket 21. Chain 22 which is set between the output sprocket 
21 and the input sprocket 18 transmits the driving force from the first 
motor 19 to the shape-forming roller 4 through those constituent members 
20 through 22 and 16 through 18 mentioned above in order that the 
shape-forming roller 4 can independently rotate itself. On the other hand, 
connecting shaft 24 having ball joints 23/23 on both sides is coupled to 
the supporting roller 13, while an end of this shaft 24 is coupled to 
pulley shaft 25 which is connected to input pulley 26. The rotary shaft 28 
of the second motor 27 independently driving the supporting roller 13 is 
coupled to output pulley 29, while V-shaped belt 30 installed between the 
output pulley 29 and the input pulley 26 transmits the driving force from 
the second motor 27 to the supporting roller 13 through those constituent 
members 28 through 30 and 24 through 26 mentioned above in order that the 
supporting roller 13 can independently rotate itself. 
Contact element of contact sensor 31 comes into contact with the external 
circumference of the work piece 14 having a specific diameter expanded by 
the rolling process. In response to signals input from contact sensor 31 
and in accordance with programs stored in ROM 32, CPU (central processing 
unit) 40 properly controls the driving operations of the pressing cylinder 
1, the first motor 19, the mandrel position-shifting cylinder 8, and 
inverter 33, respectively. Note that inverter 33 is substantially the 
frequency changer which allows a power-supply source having a specific 
frequency to generate power having an optional frequency in order that the 
number of the rotation of motors can freely be changed. RAM 34 stores all 
the data needed for executing the numerical control operations described 
later on. A potentiometer can be installed to the base of contact sensor 
31. 
Assume that the number of the rotation of the shape-forming roller 4 is N1 
and the number of the rotation of the supporting roller 13 N2, 
respectively, then the relationship between these can be expressed by the 
equation shown below. 
##EQU1## 
where D1 denotes the diameter of the wheel-body shape-forming portion 4a 
of the shape-forming roller 4; D2 denotes the diameter of the contact 
surface 13a of the supporting roller 13; D3 denotes the diameter of the 
wheel-body shape-forming portion 5a of the mandrel 5; D4 denotes the 
diameter of the regulated surface 5b of the mandrel 5; Di denotes the 
internal diameter of the work piece 14; and D0 denotes the external 
diameter of the work piece 14, respectively. 
RAM 34 stores a variety of data corresponding to N1, D1 through D4, 
respectively. The first preferred embodiment of the wheel-body forming 
apparatus related to the invention features the constitution mentioned 
above. Next, functional operation of the wheel-body forming apparatus 
reflecting the first preferred embodiment is described below. 
As soon as the work piece 14 is delivered from the work-supplying unit (not 
shown) placed between the shapedforming roller 4 and the supporting roller 
13, CPU 40 then activates the movement of the mandrel position-shifting 
cylinder 8 from the stand by position to the shape-forming position shown 
in FIG. 1. This allows the mandrel 5 to pass through he hole of the work 
piece 14 in order that the wheel-body shape-forming portion 5a can be 
delivered to a specific position exactly being opposite from the 
wheel-body shape-forming portion 4a of the shape-forming roller 4 through 
the work piece 14. Next, CPU 40 activates the operation of the first motor 
19 to rotate the shape-forming roller 4, and simultaneously, CPU 40 also 
activates the operation of the second motor 27 via inverter 33 so that 
both the supporting roller 13 and the mandrel 5 can start to rotate 
themselves together. CPU 40 then activates the forward movement of the 
pressing cylinder 1 to shift the position of the shape-forming roller 4 
unit it comes into contact with the supporting roller 13 by operating 
piston rod 2. This also allows the wheel-body shape-forming portion 4a of 
the shape-forming roller 4 to come into contact with the external 
circumference of the work piece 14. Next, when the shape-forming roller 4 
is pressed, the work piece 14 is rotated by the wheel-body shape-forming 
portion 4a of the shape-forming roller 4 and the wheel-body shape-forming 
portion 5a of the mandrel 5 so that cold rolling process can be executed 
for the work piece 14 until it is rolled into the predetermined dimension 
as shown in FIG. 3. 
The value of Di/D0 gradually increases itself during the rolling process 
from the starting time to the completion of this process before reaching a 
specific value close to 1 (one). CPU 40 properly controls the operation of 
inverter 33 in response to the work-measured signal sent from contact 
sensor 31, while CPU 40 simultaneously controls variable number of the 
rotation of the second motor 27 in accordance with an expression 
N2.apprxeq.N1.times.Di/D0. This causes the number of the rotation N2 of 
the supporting roller 13 to vary itself relative to the number of the 
rotation of the shape-forming roller 4 in accordance with the variation of 
the diameter of the work piece 14. The work piece 14 receives a specific 
rotation torque from the shape-forming roller 4 and the mandrel 5. This 
allows the apparatus related to the invention to precisely form up the 
work piece 14 having the perfect roundness by securely preventing the work 
piece 14 from extending itself in the direction of tangent. Furthermore, 
since the first and second motors 19 and 27 respectively and independently 
drive the shape-forming roller 4 and the supporting roller 13, the work 
piece 14 receives a specific rotation torque from the shape-forming roller 
4 and the mandrel 5 driven by the supporting roller 13. As a result, no 
slip can be generated between the mandrel 5 and the supporting roller 13, 
thus eventually improving the durability of the mandrel 5. Furthermore, 
even when the shape-forming roller 4 is worn out by repeated rolling 
operations or when forming a work piece having different diameters by 
employing different-diameter shape-forming roller, since the numbers of 
the rotation N1 and N2 of the shape-forming roller 4 and the supporting 
roller 13 vary themselves, the wheel-body forming apparatus reflecting the 
first preferred embodiment can fully achieve the aimed forming precision 
by allowing inverter 33 to preliminary set up an optional frequency by 
manual means for example. 
Since the inverter 33 varies the power frequency (50 or 60 Hz) from 30 Hz 
to a maximum of 180 Hz without steps, presence of this inverter 33 between 
the power-supply source and the AC motors allows CPU 40 to easily control 
the number of the rotations of all the rotative members without performing 
complex operations otherwise needed for controlling the number of the 
rotation of those motors such as the switching of the variable-speed gears 
and the number of motor electrodes for example. 
Furthermore, since the supporting roller 13 receives the mandrel 5, 
pressure-resistance strength of the mandrel 5 during the rolling process 
is significantly improved. In addition, since the mandrel 5 is rotated by 
the supporting roller 13 and the shape-forming roller 4 which respectively 
press themselves against both sides of the mandrel 5, the mandrel 5 can 
easily be driven. Since members of the work piece 14 are set in free 
condition except for those portions surrounded by the wheel-body forming 
portions 4a and 5a, the apparatus related to the invention can effectively 
execute the rolling operation against the work piece 14 by providing 
satisfactory elongation in the direction of the diameter as required. The 
description of the first preferred embodiment of the invention merely 
refers to the operation needed for forming up the outer race of bearing. 
However, it is also possible for the apparatus related to the invention to 
form a wide variety of wheel bodies by applying different mandrels and 
shape-forming rollers suited for processing the inner race and pillow of 
bearing or automotive parts like gauge and sleeve, or the like. 
(The Second Preferred Embodiment) 
To implement the second preferred embodiment, the wheel-forming apparatus 
related to the invention can dispense with contact sensor 31 and CPU 40 
employed for implementing the first preferred embodiment. Instead, the 
second preferred embodiment allows provisions of the following: The 
operator can preliminary set the number of the rotation of the second 
motor 27 in order that it can correctly match the faster rotation number 
N2 of the supporting roller 13 at the moment when completing the 
shape-forming operation. The apparatus related to the invention then 
causes V-shaped belt 30 to slip itself during the initial stage of 
shape-forming operation in order that the slow-rotation number N2 of the 
supporting roller 13 can be generated during the initial stage of 
shape-forming operation. Finally, the controller causes the second motor 
27 to be activated in order that the number of the rotation of the second 
motor 27 can be held constant to properly control the number of the 
rotation of the supporting roller 13 stepwise by effectively applying the 
slipping movement of V-shaped belt 30. The constitution mentioned above 
provides the apparatus related to the invention with simplified mechanical 
requirements. The apparatus related to the second preferred embodiment 
securely achieves satisfactory effect of the wheel-body forming identical 
to that of the first preferred embodiment. Furthermore, the slipping 
movement of V-shaped belt 30 effectively prevents overcurrent from flowing 
through the second motor 27. 
(The Third Preferred Embodiment) 
FIG. 4 denotes the third preferred embodiment of the wheel-body forming 
apparatus related to the invention. Output shaft 36 of oil-pressure motor 
35 capable of varying the amount of waste oil is coupled to connecting 
shaft 24 connected to the supporting roller 13. Signal output from CPU 40 
controls those factors needed for variably controlling the numbers of the 
rotations of those constituents including the inclined shaft and the 
inclined plate inside of oil-pressure motor 35. This stabilizes pressure P 
corresponding to torque and allows the controller to variably control only 
the flow rate Q corresponding to the numbers of the rotations of those 
rotative constituents mentioned above. By effectively driving the compact 
and light-weight oil-pressure motor 35 making up the second driving 
source, the apparatus related to the third preferred embodiment of the 
invention securely generates the desired rotation torque. Furthermore, 
this motor 35 can effectively use the oil-pressure source in common with 
cylinders 1 and 8, and yet, by merely adding a relief valve, the 
oil-pressure motor 35 can easily prevent itself from incurring mechanical 
damage. The constitution mentioned above allows the apparatus related to 
the third preferred embodiment to generate satisfactory effect of the 
wheel-body forming identical to that of the first preferred embodiment. 
Those portions shown in FIG. 4 corresponding to those which are shown in 
FIG. 1 are provided with identical reference numerals and symbols, while 
the detailed description of these are deleted. 
(The Fourth Preferred Embodiment) 
FIG. 4 denotes the fourth preferred embodiment of the wheel-body forming 
apparatus related to the invention. The apparatus shown in FIG. 5 uses the 
first servo motor 37 in place of the oil-pressure motor 35. Output shaft 
38 of the first servo motor 37 is coupled to an end of connecting shaft 24 
in order to independently transmit the driving force from the first servo 
motor 37 to the supporting roller 13 via the output shaft 38 and 
connecting shaft 24, respectively. Pressing means 39 pressing itself 
against the movable frame 3 causes the main gear 43 coupled to the output 
shaft 43 of the second servo motor 41 and the follower gear 45 coupled to 
screw 44 to be engaged with each other constantly. This in turn allows the 
driving force from the second servo motor 41 to be transmitted to screw 44 
via those gears 43 and 45 to allow screw 44 to move the movable frame 3 in 
the forward and backward directions. Contact element of contact sensor 31 
comes into contact with the external circumferential surface of the work 
piece 14 having a specific diameter expandable by the rolling operation. 
Signals from contact sensor 31 are delivered to CPU 40 via encoder 46. In 
response to signals from the second servo motor 41 and encoder 46 and in 
accordance with programs stored in ROM 32, CPU 40 properly controls 
operations of the mandrel position-shifting cylinder 8, the first motor 
19, and the first servo motor 37. RAM 34 stores those data needed for 
allowing CPU 40 to execute all the control operations. In the fourth 
preferred embodiment, the apparatus related to the invention uses 
absolute-type rotary encoder 46 which encodes the value of the external 
circumferential surface of the work piece 14 received from contact sensor 
31. By effectively incorporating those constituent members including the 
first motor 19 making up the first driving source, the first servo motor 
37 making up the second driving source, and the second servo motor 41 
making up part of shape-forming pressing means 39, the wheel-body forming 
apparatus reflecting the fourth preferred embodiment of the invention 
generates those functions described below. 
The value Di/D0 gradually increases during the cold rolling process from 
the starting time to the completion of this process before reaching a 
specific value close to 1 (one). In accordance with the signal indicating 
the measured value of the external diameter of the work piece 14 received 
from contact sensor 31 and encoder 46 and also those signals indicating 
the amount of pressure and the amount of the delivered screw received from 
the second servo motor 41, CPU 40 computes the thickness "t" and the 
external diameter D0 of the work piece 14 to determine the value of Di/D0. 
CPU 40 then formulates the value of the internal diameter Di of the work 
piece 14 so that it corresponds to Di=D0-2t before eventually controlling 
the variable rotation number of the first servo motor 37 in conformity 
with the equation shown below. 
##EQU2## 
Consequently, the work piece 14 receives a specific rotation torque from 
the shape-forming roller 4 and the mandrel 5. CPU 40 then causes the 
number of the rotation N2 of the supporting roller 13 to vary itself 
relative to the number of the rotation N1 of the shape-forming roller 4 in 
response to the varying diameter of the work piece 14 until the value N2 
can eventually match the equation shown above. This eventually allows the 
apparatus related to the fourth preferred embodiment to precisely form up 
the work piece having the perfect roundness by effectively preventing the 
work piece from expanding itself in the direction of the tangent of those 
rollers mentioned above. Furthermore, since the first motor 19 and the 
first servo motor 37 respectively and independently drive the 
shape-forming roller 4 and the supporting roller 13, the work piece 14 
receives a specific rotation torque from the shape-forming roller 4 and 
the mandrel 5 driven by the supporting roller 13. As a result, no slip can 
be generated between the mandrel 5 and the supporting roller 13, thus 
eventually improving the durability of mandrel 5 itself. Furthermore, even 
when the shape-forming roller 4 is worn out by repeated rolling operations 
or when forming a special work piece having different diameters by 
employing a different-diameter shape-forming roller, since the numbers of 
the rotation N1 and N2 of the shape-forming roller 4 and the supporting 
roller 13 are respectively variable by NC (numerical control) means in 
conjunction with the equation shown above, the wheel-body forming 
apparatus reflecting the fourth preferred embodiment can precisely form up 
the objective work piece. In addition, by virtue of negligible amount of 
inertia and satisfactory follow-up characteristic, the first and second 
servo motors 37 and 41 precisely control the numbers of the rotations of 
those rotative constituents mentioned above. In particular, numerical 
control means mentioned above is substantially of absolute type capable of 
correctly memorizing the origin positions of the movable constituents 
themselves needed for making up the origin of programs to be executed, and 
thus, even if the power-supply source were provisionally cut off, the 
numerical control system correctly follows up numerical control operations 
after resumption of the power supply service. This in turn allows 
operators to easily replace the rotative constituents of the apparatus 
shown in FIG. 5 as required. Note that those constituents of the apparatus 
shown in FIG. 5 are provided with reference numerals and symbols identical 
to those which are shown in FIGS. 1 and 4. 
It is also possible for the fourth preferred embodiment of the apparatus 
related to the invention to use a servo motor in place of the first motor 
19 to permit the controller to variably control the numbers of the 
rotation N1 and N2 in order that the numerical control system can more 
precisely implement control operations. It is recommended that ball screws 
be made available for screw 44. 
The wheel-body forming apparatus related to the invention may also be used 
for removing deflected part from the forged wheel body and also for 
expanding the diameter of the pressed wheel body as well. Needless to say 
that both ends of the mandrel 5 are properly held throughout the rotating 
operations of all of those rotative constituents of the wheel body forming 
apparatus related to the invention. 
While only certain embodiments of the invention have been described, it 
will be apparent to those skilled in the art that various changes and 
modifications may be made. However, such variations are not to be regarded 
as a departure from the spirit and scope of the invention, but all such 
modifications are included within the scope of the following claims.