Hot rolling pilger mill

The feeder and the rolls are operated by separate cranks to avoid obstruction of the area in which the hollows are connected to the feeder. The two cranks are either separately driven or connected to a common drive; in either case, synchronism is maintained, and, preferably, an alternating retarding and advance component of movement is superimposed on one crank in relation to the other so that the feeder drive can take up some of the deforming work.

BACKGROUND OF THE INVENTION 
The present invention relates to hot pilger rolling, and more particularly, 
the invention relates to improvements in a hot pilger rolling mill. 
A rolling mill of the pilger type is usually comprised of a fixed frame and 
stand supporting bearing blocks or roll mounts which can be displaced 
transversely to the direction and axis of rolling. A pair of pilger type 
rolls are journalled in these blocks or mounts and the rolls caery pinions 
meshing a gear element in driving engagement, particularly for imparting 
oscillating movement upon the rolls. The gear elements are being driven 
from a main drive. A feeder is disposed in the line of rolling and 
includes a longitudinally movable carriage or slide on which is mounted 
the mandrel rod holder and other equipment. 
In my copending application Ser. No. 886,539, filed Mar. 14, 1978, now U.S. 
Pat. No. 4,152,917 granted May 8, 1979, I have disclosed two journal gear 
segments on the bearing blocks or roll mounts. These segments are 
preferably provided with internal gearing and mesh pinions on the rolls 
for driving them. A crank mechanism is provided to drive and reciprocate 
the feeder for the mill; in addition, the segments are coupled to that 
crank mechanism to be driven thereby to obtain oscillatory movement of the 
rolls. 
DESCRIPTION OF THE INVENTION 
It is an object of the present invention to improve rolling mills of the 
pilger rolling variety which avoids the use of coupler rods between the 
crank and the immediate roll drive device such as the segments mentioned 
above. 
It is a further object of the present invention to provide a new and 
improved rolling mill of the type outlined above which permits a 
controlled distribution of load between roll drive and feeder; for 
example, the deforming work is to be taken up in parts by the feeder 
during the initial phase of a piler pass. 
In accordance with the preferred embodiment of the invention, it is 
suggested to provide separate cranks for the feeder and for the rolls and 
to separately couple the two cranks by means of linkage means including 
coupler rods, to the feeder and to the rolls respectively. The two cranks 
are driven in synchronism either by means of a common drive with separate 
output transmission branches leading to the two cranks, or by means of two 
drives which are forced to drive in synchronism with each other. In the 
latter case, it is of advantage to place the feeder drive and the crank on 
a carriage which is stepwise separately advanced. This way, one reduces 
the total weight of the parts being reciprocated as part of the feeder 
operation. One of the two linkage means includes a rocking lever, 
adjustably connected to and operated by the respective crank or linkage 
rod. The synchronous movements of th cranks are modified by superimposing 
a component upon one of them to periodically alter the relation of the 
movements of the crank as between advance and retarding. This way, some of 
the rolling work is taken up by the feeder drive.

Proceeding now to the detailed description of the drawings, the pilger 
rolling mill depicted in FIGS. 1 and 2 is comprised of a main stand 1 for 
pilger type rolls 2 and 3, being journalled for rotation in the stand. The 
hollow 8 to be rolled is positioned by means of a feeder 4, which is 
constructed basically as a reciprocating carriage on a stationary bed 5. 
The feeder 4 is driven by means of a main drive 6, which drives other 
components as well. The carriage is driven by drive 6 via a crank 7, to be 
described in detail below. The hollow blank 8 sits on a cylindrical 
mandrel rod 9 for placement between the two rolls 2 and 3 to obtain 
rolling of the hollow by means of reciprocation of the crank driven 
mandrel rod 9. 
The elements as described thus far constitute the major components of the 
mill. The rolls 2 and 3 are journalled in block inserts or roll mounts 
whereby roll 2 is journalled in the two inserts 12 and 12', and roll 3 is 
journalled in insert or roll mount 13, and a second one, behind 13' in 
FIG. 1, and arranged analogously and in vertical alignment with insert 
12'. These inserts are adjustably mounted in the stand to adjust the width 
of the rolling gap and to exchange worn rolls. 
A shaft 15 is journalled also in inserts 13 and 13', carrying a gear 
segment 17. The segment 17 has an inner gear meshing a pinion on the shaft 
of roll 3. A similar shaft 14, carrying a similar gear segment (not shown) 
meshes a pinion on the shaft of upper roll 2. This additional gear segment 
and pinion is situated in a plane in front of the plane of the drawing of 
FIG. 1. Further details of the roll stand and the drive segments are shown 
in my copending application Ser. No. 886,539. 
The mandrel rod 9 is connected to a feeder rod 10 by means of a lock 11. 
The rod 10 advances and retracts with the carriage of the feeder, and is 
also provided for rotation by means of a rotating drive 45. The carriage 
of the feeder 4 includes a feed slide 35 which can slide on the movable 
bed 37, being the base element of the carriage and being provided to move 
on stationary bed 5. The feeder rod 10 is hydraulically centered in the 
top part of feed slide 35. The hydraulic centering is described in greater 
detail in my copending application, Ser. No. 886,539. Centering is also 
possible by means of springs. 
A drive, not illustrated, moves slide 35 on bed 37 to obtain the stepwise 
advance of hollow 8 between the rolls 2 and 3 for sequential passes. In 
other words, this additional drive stepwise repositions the hollow as to 
the onset for each of the sequential pilger passes. The carriage as a 
whole and bed part 37 in particular, is driven as follows. The crank arm 7 
is rotated by a crank 46 which is driven by drive 6. The crank arm 7 is 
connected to one end of a rocking lever 34 whose other end is, for 
example, pivoted on the base 5. A drive rod or arm 38 is connected to 
rocking lever or arm 34 at an adjustable distance from either end of 
rocking lever 34, and that drive rod 38 is connected to the movable bed 37 
to drive same. The adjustable connection between parts 34 and 38 permits 
adjustment of the linkage to different roll diameters. 
The drive 6 is further drivingly connected to a shaft 55 which is connected 
to a shaft 55' via a planetary type gear 49. The shaft 55, in turn, is 
geared to another crank 47 operating a pair of crank arms 48 and these 
crank arms are pivotally linked, respectively, to the two gear segmens 17 
by means of pivot linkages such as 27. Thus, the crank arrangement 47, 48 
moves the segments 17 back and forth. 
The gear 49 has a housing 50 which, when moved, superimposes a relative 
movement upon shaft 55. A crank arm 51 is connected to a point on rocking 
lever 34 to thereby drive the gear housing 50. This connection in general 
and the crank arm 51 in particular provide for a change in relative speed 
between the feeder and the rolls. In particular, the modification of the 
roll speeds as so introduced permits the rolls and feed drives to 
periodically alternate between advance and retarding of one relative to 
the other. Particularly, during a rolling pass, the feeder may advance to 
thereby cause the feeder drive (crank 46, 7, etc.) to take up some of the 
deforming work. Towards the end of the rolling pass, during sizing, the 
feeder may be retarded so that part of the braking can be used to drive 
the rolls. It should be realized that the planetary gear by means of which 
one superimposes a relative component of movement as between the two 
cranks, could be placed into the drive train that leads to the crank 46, 
7, and the superimposed component is taken from the other crank and/or the 
linkage thereof to the rolls. 
The arm 51 is chosen as being linked in a fixed point on arm 34, but just 
as rod 38 is adjustably linked to arm 34, so can crank arm 51. It should 
also be realized that the drive point for the crank 51 can be taken from 
other portions of the crank feeder drive train 46, 7, 34, 38. Still 
alternatively, one could use a piston drive for the housing 50. 
FIG. 3 illustrates a modification of the mill as shown in FIGS. 1 and 2, 
but many parts and components are similar. This similarity involves 
particularly the provision of the two cranks 46, 47, and the parts being 
driven by them, i.e. the rolls and the feeder. Different is that the two 
cranks 46, 47 are driven by separate drives each having its own drive 
motor, respectively, denoted 53 and 52. 
The drive 53 for crank 46 and the parts driven by it are all disposed on 
slide 35. Slide 35 is moved on bed 5 in steps of the rolling passes and by 
means of a drive 54 with reducing gear 54'. Thus, the relationship is 
reversed in this case as far as feeder positioning and feeder 
reciprocating is concerned. Nevertheless, the masses being moved in this 
example are lower than in the device of FIGS. 1 and 2. 
The motor 52 just drives the crank 47 and the crank arms 48, being coupled 
to the roll drive segment gears as described. The motors 52 and 53 may 
well be mechanically coupled to each other because the linear output 
speeds involved are low in both instances. For example, one could provide 
a coupling shaft constructed as a splined shaft between the motors to 
enforce a synchronous run. However, it is simpler to control the drive 
motors 52 and 53 electrically to obtain synchronous operation. It is 
important that upon stopping, the cranks 46, 47 must retain their 
position. For this, it is, for example, suggested to use shoe brakes. The 
advance of the reciprocating feeder 4 relative to rolls 2 and 3 during a 
rolling pass proper can also be realized electrically, whereby a control 
pulse is derived through a suitable transducer either from the carriage 4 
or from one of the rolls 2, 3 to control the drive for the respective 
other one. 
It can readily be seen that in both examples the space between and 
adjoining feeder 4 and roll stand 1 is unoccupied so that the feeding of 
hollow stock and withdrawal of the rolled hollow is unimpeded by linkage. 
The shaft 55 can be regarded as a coupling element as between the cranks, 
but it can be well hidden under the floor of the plant. Moreover, the 
dynamic coupling of the cranks and alternating between retarding and 
advance phase during a pass, particularly upon relatively advancing the 
carriage in relation to the rolls 2 and 3, the drive 46, 53 can actually 
take up part of the deforming work. 
The invention is not limited to the embodiments described above but all 
changes and modifications thereof not constituting departures from the 
spirit and scope of the invention are intended to be included.