Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The present invention relates to the technique
known as rotary forging, wherein two shaping rolls take a
blank workpiece for shaping between two diametrically
opposite contact areas on the rolls, which are rotated.
The rolls drive the workpiece without any slipping, and
exert on the workpiece a deforming pressure such as to give
to the latter a profile corresponding to the profiles of
the shaping rolls. The rolls are re~uired to rotate in
synchronism and the relative angular positions of their
profiles should be adjusted with accuracy so that the mark
left by one of the rolls on the workpiece meshes perfectly,
after a half-turn rotation of the workpiece, with the
design of the other wheel. This technique is used in the
production of threads and involute grooves, and in tooth
cutting, and in the production of revolving parts with
complex profiles, etc.
The present invention is concerned with accurate
adjustment of the relative angular positions of at least
two of such shaping rolls to arrive at the result indicated
hereinabove. An object of the invention is to achieve
accuracy, in a simple and reliable way, during the
operation of the rotary forging machine, and whatever the
intensity of the forces exerted.
According to the invention there is provided a
device for accurately adjusting the relative angular
positions of shaping rolls in a rotary forging machine,
wherein at least two shafts which are required to rotate in
the same direction and synchronously are provided with said
shaping rolls and with helical-tooth driven gears which are
rotatable with said shafts in constant engagement with at
least one conjugate-tooth driving gear which is coupled to
a driving device, one at least of said gears being axially
displaceable and connected to a micrometric device for
adjusting the axial position of said axially displaceable
gear for determining the relative angular positions of said
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driven gears in accordance with the inclination of the
teeth.
According to a particularly advantageous
embodiment of the invention, the device comprises only one
helical~tooth driving gear which is in engagement with the
identical conjugated ones of at least two of the driven
gears, only one of which is axially displaceable, the
micrometric adjustment device acting on the axially
displaceable driven gear. Preferably, the adjusting means
comprise a micrometric screw and nut transmission of which
the screw which is coupled to a control means and retained
against axial displacement and co-operates with a nut,
which is axially displaceable and retained against
rotation, said nut being integral with a fork engaged on
the axially displaceable driven gear.
The invention will be more readily understood on
reading the following description of emhodiments thereof
with reference to the accompanying drawings in which:
FIGURE 1 is a perspective view showing a first
embodiment of the adjusting device according to the
invention.
FIGURE 2 is a cross-sectional view along line
II-II of Fig. 1 compared with a different parallel
cross-sectional view of the device of Fig. 1.
FIGURE 3 is a similar view to that shown in Fig.
1, illustrating a second embodiment of the invention.
The rotary forging machine comprises a
moto-reducer or moto-variator set 1 provided for
rotationally driving in synchronism two shafts 2 and 3 on
which are mounted, either directly or via inclinable shafts
co-operating with Cardan joints as in certain mills,
coldshaping wheels 4 and 5 designed to shape a workpiece 6
interposed therebetween (Figure 2).
According to the embodiment illustrated in Fig.
1, the output member of the set 1 is connected, via a
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sliding coupling, to a driving shaft 7 integral with two
gears 8 and 9, having symmetrically-inclined helical
teeth. The driving gear 8 is in permanent engagement with
a conjugate-tooth driven gear 10, integral with the driving
shaft 2. In like manner, the driving gear 9 is in
permanent engagement with a conjugate-tooth driven gear 11,
integral with the driving shaft 3. The helical teeth of
the driven gears 10 and 11 are symmetrically inclined, just
as the helical teeth of the driving gears are; and like the
latter, the driven gears are axially offset and therefore
are not facing one another.
Referring now to Fig. 2, this shows that the
driving gear 8 is in contact with the driven gear 10 in the
zone A and the driving gear 9 is in contact with the driven
gear 11 in the zone B, the two zones A ~ B being
diametrically opposite. In like manner, the wheel 4 is in
contact with the workpiece 6 in a zone C which is
diametrically opposite to the contact zone D of workpiece
with the wheel 5. It is quite obvious that the marks left
at C and D on the workpiece 6 by the wheels 4 and 5
respectively, will, once the piece has made a half-turn
rotation, cover the designs which follow correspondingly
with the rotation, not on the wheels 4 and 5, but on the
wheels 5 and 4. It is therefore important for the angular
position of the wheels one with respect to the other to be
perfectly accurate so that the designs of each one are
printed into the workpiece, following strictly the mark
left by the designs of the opposite wheel. It is therefore
necessary to be able to accurately adjust, at any moment,
the relative angular positions of the wheels, i.e. of
points C and D, and consequently, the relative angular
positions of the driven gears 10 and 11, i.e. of points A
and B. This angular position however varies when the
driving gears 8 and 9 are moved in coaxial translation,
this because of the inclination of the helical teeth.
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Obviously, no axial pressure is exerted on the
shaft 7, since the teeth of the driving gears 8 and 9 which
are comparable to double-helical gears, cancel out the
axial reactions, because of the symmetry.
According to the embodiment illustrated in Fig.
1, the device for adjusting the said position comprises a
micrometric screw and nut transmission comprising a screw
12 integral with a rod 13 of which one end is coupled to
the shaft 7 via a double-action thrust ball bearing 14
which transmits the axial displacement of the screw to the
shaft in both directions, but not the rotation of the
latter to the screw; in fact, the other end of the rod is
guided for axial displacement in a support 15 and prevented
from turning by a key 16; the nut 17 is free in rotation
but retained from axial displacement by a fork 18 integral
with the fixed support 15. The adjusting device further
comprises worm gearing for controlling the adjustment; the
gear 19 is cut on the periphery of the nut 17 and the worm
20 which meshes with the gear 19 is carried by an operating
lever 21. The lever 21 is pivotally mounted and retained
against axial displacement in the fixed body 22 of a meter
23; it is provided with a knob 24 or with a gripping handle
for adjusting purposes.
Thus, by operating the knob 24, the worm 20 is
caused to pivot and as a result the gear 19 and the nut 17
with which it is fast, the effect being an axial
displacement, in one direction or in the opposite one, of
the micrometric screw 12, which latter drives in the same
movement the driving gears 8 and 9. As a result, the
driven gears 10 and 11 are angularly offset one with
respect to the other. The adjustment is effected until the
marks left by the wheels 4 and 5 on the workpiece 6
coincide perfectly.
According to a second embodiment of the invention
illustrated in Fig. 3, the device comprises, as previously,
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a set 1, a driving shaft 7 and driven shafts 2, 3 which
drive coldshaping wheels 4, 5 designed for shaping a piece
6 interposed between them.
However, in this second embodiment, the driven
shafts 2 and 3 are integral with gears 25 and 26 which are
normally situated one opposite the other and the respective
~elical teeth of which are identical and have the same
inclination. The gears 25 and 26 are in engagement with a
driving gear 27 coupled to the shaft 7 and the helical
teeth of which are symmetrical relative to the teeth of the
driven gears.
In this particular embodiment, the adjusting
device, as shown in Fig. 3, also comprises a micrometric
screw and nut transmission. The nut 2~ is guided for axial
or longitudinal displacement by a fixed guide track 29
; which prevents it from rotating and it is integral with a
fork 30 which transmits the axial displacement of the nut
to the driven gear 26. The screw 31 which co-operates with
the nut is free to rotate but a rod 32 with which it is
fast and which is provided with a control knob 33, is
retained against axial displacement inside the fixed body
of a meter 35.
As a result, by operating the knob 33, the screw
31 is caused to pivot, axially displacing the nut 27 and,
via the fork 30, the driven gear 26. Due to the coupling
of the three gears and to the inclination of their teeth,
the axial displacement generates a relative angular offset
of the teeth of the driven gears 25 and 26, hence of the
wheel-carrying shafts 2 and 3.
In this case, an axial thrust is exerted on the
shaft 3, because of the reaction of the teeth. However,
since the inclination of the teeth is slight, the thrust is
relatively small and can easily be taken up by the thrust
bearings of the shaft.
The machine can of course comprise more than two
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shaping wheels and as many driving shafts coupled to as
many driven gears meshing with at least one driving gear.
In this case, at least one of these helical-tooth gears
should be axially movable in order to be able to adjust the
relative angular wedging of all the wheels.
The invention is in no way limited to the
embodiments given hereinabove and on the contrary various
modifications can be brought thereto without departing from
the scope thereof.
