Heatable roll for use in calenders and the like

A calender roll wherein a cylindrical shell is rotatably mounted on a stationary carrier by way of bearings which are disposed in the end portions of the shell. The median portion of the shell is heated by a first heating device, and the end portions of the shell are heated by a discrete second heating device. The second heating device has channels which are provided in the end portions of the shell and/or indictive heaters which are adjacent to the exterior of the end portions of the shell. Alternatively or in addition to such expedients, the second heating device can include the bearings in the end portions of the shell; each such bearing includes or constitutes an axial or radical hydrostatic bearing which is heated by hydraulic fluid to thereby heat the respective end portion of the shell. The second heating device ensures that the effective length of the shell approximates or even matches the axial length of the shell.

BACKGROUND OF THE INVENTION 
The invention relates to improvements in rolls for use in calenders and 
like machines wherein webs of paper, plastic, textile or other material 
are caused to advance through the nip or nips of one or more pairs of 
rolls. More particularly, the invention relates to improvements in 
heatable rolls for use in calenders and like machines. 
Commonly owned U.S. Pat. No. 4,757,584 to Pav et al. discloses a roll 
wherein the internal space of a hollow cylindrical shell, which is 
rotatable about a stationary carrier, receives at least two sets of 
hydrostatic bearing elements which are installed between two inserts. The 
inserts include antifriction bearings for the end portions of the shell, 
and twin sealing elements which prevent lubricant for the antifriction 
bearings from reaching the hydraulic fluid flowing to, in and from the 
hydrostatic bearing elements between the inserts. The median portion of 
the shell can be heated by such hydraulic fluid. The purpose of 
hydrostatic bearing elements is to permit adjustments of the width of the 
nip or nips which the cylindrical external surface of the roll defines 
with one or more neighboring rolls. An advantage of the patented roll is 
that hydraulic fluid which is used to change the configuration of the roll 
(by admitting pressurized hydraulic fluid to selected bearing elements 
and/or by permitting hydraulic fluid to escape from selected bearing 
elements) also forms part of the means for heating the median portion of 
the shell, either alone or in conjunction with additional heating means. 
The useful length of the external surface of the roll is that between the 
two inserts. In other words, the useful portion of the nip or nips between 
the patented roll and one or more adjacent rolls does not exceed the 
distance between the inserts in the end portion of the shell. 
It is often necessary to heat the fluid which is supplied to the 
hydrostatic bearing elements to an elevated temperature in the range of 
250.degree. to 350.degree. C. When the median portion of the shell is 
heated by a hydraulic fluid which is supplied at such elevated 
temperatures, the effective width of the nip or nips which are defined by 
the external surface of the shell is even less than the distance between 
the two inserts. The reason is that the temperature of the shell decreases 
rather abruptly in regions which are adjacent the inserts. Consequently, 
the actual length of the roll must greatly exceed the effective width of 
the nip or nips, and this contributes significantly to space requirements 
and initial and maintenance cost of the roll as well as to the space 
requirements and cost of the entire machine in which the roll is put to 
use. This also necessitates the use of a frame wherein the two lateral 
frame members are disposed at a considerable distance from each other, 
especially if the machine embodying the roll is used for the treatment of 
wide or extremely wide webs of paper, plastic material, fabric or the 
like. The cost of regulating the configuration of the shell in a heated 
calender roll increases with the length of the roll, and the accuracy of 
regulation is also affected if the roll must employ a long shell because 
only the median portion of the shell can be heated with a requisite degree 
of predictability. Moreover, a calender or a like machine with long or 
extremely long rolls cannot be readily installed in many existing plants. 
OBJECTS OF THE INVENTION 
An object of the invention is to provide a roll wherein the difference 
between the effective and actual lengths of the shell is less than in 
heretofore known rolls. 
Another object of the invention is to provide a novel and improved heatable 
roll for use in calenders and like machines. 
A further object of the invention is to provide novel and improved means 
for heating the roll of a calender or the like. 
An additional object of the invention is to provide novel and improved 
means for heating selected portions of the shell in a roll for calenders 
and the like. 
A further object of the invention is to provide a calender or like machine 
which embodies the above outlined roll. 
Another object of the invention is to provide a novel and improved shell 
for use in the above outlined roll. 
An additional object of the invention is to provide novel and improved 
inserts for use in the shell of the above outlined roll. 
A further object of the invention is to provide novel and improved bearings 
for the end portions of the shell in the above outlined roll. 
SUMMARY OF THE INVENTION 
The invention is embodied in a roll which can be used in calenders and like 
machines. The improved roll comprises a hollow tubular shell having an 
internal space and first and second end portions adjacent the end faces of 
the shell, first and second inserts which are installed in the first and 
second end portions, respectively, a first heating device having means for 
heating the shell between the inserts, and a discrete second heating 
device for heating the shell in the region of each of its end portions. 
The shell has a preferably cylindrical external surface which cooperates 
with the external surface of at least one adjoining roll to define a nip 
for a running web of paper, plastic material, textile or the like. Still 
further, the roll normally comprises a carrier for the shell. The latter 
surrounds the carrier and is rotatable relative thereto. The first heating 
device can comprise hydrostatic bearing elements which are disposed in the 
internal space of the shell between the two inserts, a source of hydraulic 
fluid, means for heating the fluid, and means for conveying fluid from the 
fluid heating means to the hydrostatic bearing elements. 
Each insert takes up a predetermined length of the internal space in the 
axial direction of the shell, and the external surface of the shell 
preferably extends around the internal space between the two inserts and 
also along at least 50 percent of each predetermined length of the 
internal space. 
In accordance with one presently preferred embodiment, the second heating 
device includes at least one inductive heater outwardly adjacent each end 
portion of the shell, i.e., the end portions of the shell can be heated 
from the outside. 
In accordance with another presently preferred embodiment, each insert can 
comprise at least one hydrostatic bearing and the second heating device 
then comprises a source of hydraulic fluid, means for heating the fluid, 
and means for conveying heated fluid to the hydrostatic bearings. The 
bearings can be provided with fluid-containing pockets which are inwardly 
adjacent the respective end portions of the shell. Each such bearing can 
constitute an annular bearing. The bearings define for the heated fluid 
paths which extend along the internal surfaces of the respective end 
portions of the shell. 
Each insert can comprise at least one ring-shaped member which is in 
heat-exchanging contact with the respective end portion of the shell and 
has an internal surface. The hydrostatic bearings of the inserts define 
for the heated fluid paths which extend along the internal surfaces of the 
respective ring-shaped members. 
If the hydrostatic bearings are or include radial bearings, each radial 
bearing can comprise at least one bearing ring with fluid-containing 
pockets which are adjacent the internal surface of the shell. Each radial 
hydrostatic bearing can further comprise a second bearing ring within the 
one bearing ring. The bearing rings of each radial bearing have abutting 
spherical surfaces, and the fluid conveying means can include at least one 
fluid distributing chamber between the spherical surfaces of the bearing 
rings in each radial bearing, at least one substantially radial channel 
provided in each second bearing ring and communicating with the respective 
distributing chamber, conduit means for supplying heated fluid to the 
channels, and at least one flow restricting passage provided in the one 
bearing ring of each radial bearing and connecting the respective 
distributing chamber with the respective pockets. 
If the hydrostatic bearings of the inserts include or constitute axial 
bearings, each axial bearing can comprise a wall which is in 
heat-exchanging contact with the shell by way of the internal surface of 
the shell, at least one bearing ring which is adjacent the wall, and 
fluid-containing pockets between the bearing ring and the respective wall. 
The conveying means includes means for supplying heated fluid to the 
pockets. The wall and the bearing ring of each axial bearing preferably 
have substantially radially extending abutting surfaces, and the pockets 
are provided in at least one of the abutting surfaces. It is presently 
preferred to provide the pockets in the surfaces of the bearing rings and 
to affix the walls to the shell. Furthermore, it is presently preferred to 
provide each axial bearing with two bearing rings which flank the 
respective wall and each of which is provided with fluid-containing 
pockets adjacent the respective side of the wall. 
The means for supplying heated fluid to the pockets of the axial bearings 
can comprise a substantially sealed first annular chamber adjacent the 
wall and the bearing ring or rings of each axial bearing, at least one 
second annular chamber disposed radially outwardly of each bearing ring, 
and channels which connect the first annular chamber with the respective 
second chamber or chambers. The channels preferably alternate with the 
pockets of the respective axial bearings in the circumferential direction 
of the shell. Each axial bearing can further comprise a stationary 
supporting ring for each bearing ring, and each supporting ring and the 
respective bearing ring can be provided with abutting spherical surfaces. 
Each axial bearing can further comprise a barrier which is radially 
inwardly adjacent the respective wall. The fluid supplying means for such 
axial bearings can comprise the aforementioned inner annular chambers 
which are disposed between the barriers and the respective walls, the 
aforementioned stationary carrier for the shell, and conduits provided in 
the carrier to supply heated fluid to the inner annular chambers. As 
mentioned above, each axial bearing can comprise two bearing rings which 
flank the respective wall, and each such bearing then preferably comprises 
a discrete supporting ring for each bearing ring. Each barrier is then 
flanked by the supporting rings of the respective bearing. 
In accordance with still another presently preferred embodiment, the second 
heating device comprises channels which are provided only in the end 
portions of the shell, and means for circulating a heating fluid through 
the channels. Each end portion of the shell can be provided with a 
plurality of channels which are substantially or exactly parallel to the 
axis of the shell and are adjacent each other in the circumferential 
direction of the respective end portions of the shell. Each channel can 
include a bore or hole in the respective end portion of the shell. 
Each end portion of the shell can include an outer tubular section and an 
inner tubular section within the respective outer tubular section, the 
channels are then disposed between the outer and inner tubular sections of 
each end portion. 
The means for circulating heated fluid through the channels of the end 
portions of the shell can include at least one pump, particularly a 
centrifugal pump. The pump can be provided with substantially radially 
disposed nozzles having orifices which discharge heated fluid into at 
least some of the channels. The intake ends of such orifices are or can be 
disposed in the region of the internal surface of the shell. The channels 
can include open ends in the end faces of the respective end portions of 
the shell, and the means for circulating heated fluid in such channels can 
include at least one substantially radially extending passage which 
communicates with the channels of each end portion. 
Instead of having open ends in the end faces of the respective end portions 
of the shell, the channels can be designed and distributed in the end 
portions in such a way that each end portion is provided with at least one 
first channel, at least one second channel, and a third channel which 
connects the first and second channels in the region of the end face of 
the respective end portion of the shell. The means for circulating heated 
fluid through such channels includes at least one fluid admitting inlet 
for the first channel in each end portion of the shell and at least one 
fluid receiving passage communicating with the second channel in each end 
portion of the shell. The passages are preferably remote from the 
respective end faces, the inlets are preferably nearer to and the passages 
are preferably more distant from the axis of the shell. 
The second heating device can include at least one source of heated fluid, 
means for regulating at least one parameter (particularly the temperature 
and/or pressure) of heated fluid, and means for conveying heated fluid 
from the regulating means to the aforementioned hydrostatic bearings of 
the inserts or to the channels in the end portions of the shell. The 
conveying means can include at least one passage (e.g., a channel) in the 
carrier for the shell, at least one first fluid discharging nozzle 
communicating with the passage and disposed in the region of one end 
portion of the shell, and at least one second fluid discharging nozzle 
communicating with the passage and disposed in the region of the other end 
portion of the shell. The heating channels in the end portions of the 
shell have fluid-receiving inlets in register with the respective nozzles. 
The median portion of the internal surface of the shell can be disposed at 
a greater first distance from the axis of the shell, and the outer 
portions of the internal surface (namely the portions within the end 
portions of the shell) can be located at a lesser second distance from the 
axis. The inlets of the aforementioned nozzles have fluid receiving ends 
in the respective second portions of such internal surface. Such roll can 
further comprise partitions which are provided in and divide the internal 
space of the shell into a central portion which is surrounded by the 
median portion of the internal surface and outer portions within the outer 
portions of the internal surface. The partitions serve to seal the central 
portion of the internal space from the outer portions. The second heating 
device of the just described roll can further comprise second channels 
which are provided in each end portion of the shell and communicate with 
the respective heating channels. The second channels have fluid 
discharging outlets which are axially offset with reference to the inlets 
of the respective heating channels. 
If each end portion of the shell includes an inner and an outer tubular 
section, the channels are preferably provided in the peripheral surface of 
each inner tubular section. At least one channel in each inner tubular 
section has a radially inwardly extending inlet for heated fluid. The 
inlets of such channels are preferably spaced apart from the respective 
end faces of the shell. 
If the bearings of the inserts are friction or antifriction bearings which 
require lubrication, the roll further comprises means for lubricating such 
bearings. The lubricating means can include a source of lubricant and 
means for supplying lubricant from the source to the bearings at a first 
temperature which is below the temperature of heating fluid serving to 
heat the end portions of the shell. If the inserts comprise bearings which 
must be lubricated by grease or any lubricant other than heated fluid 
which is supplied to the hydrostatic bearing elements between the two 
inserts, the roll is provided with means for sealing the median portion of 
the internal space of the shell from the outer portions, namely from the 
portions which receive the inserts and their bearings. In accordance with 
a presently preferred embodiment, each sealing means comprises a first 
sealing lip which engages or is at least adjacent the bearing of the 
respective insert, and a second lip which is adjacent the median portion 
of the internal space. 
The novel features which are considered as characteristic of the invention 
are set forth in particular in the appended claims. The improved roll 
itself, however, both as to its construction and the mode of heating the 
same, together with additional features and advantages thereof, will be 
best understood upon perusal of the following detailed description of 
certain specific embodiments with reference to the accompanying drawing.

DESCRIPTION OF PREFERRED EMBODIMENTS 
The roll 1 which is shown in FIG. can be used in a calender or in a like 
machine and comprises a hollow cylindrical shell 2 surrounding and being 
rotatable relative to a normally stationary carrier 3 The end portions of 
the carrier 3 are mounted in spherical bearings 5 which are installed in 
the respective upright frame members 4 of the machine. FIG. 1 merely shows 
the left-hand portion of the roll 1; the right-hand end portion of the 
carrier 3 is mounted in a second spherical bearing which, in turn, is 
installed in the right-hand upright frame member of the machine. The two 
halves of the illustrated roll 1 are mirror images of each other. 
The shell 2 has a cylindrical external working surface 6 which extends 
nearly all the way between its end faces, namely between two 
circumferentially complete annular shoulders 7. The external surface 6 
cooperates with the external surface of a second roll (note the roll W in 
FIG. 9) to define an elongated nip for a running web of paper, textile, 
plastic or other material which is to be treated in the machine. The nip 
can extend all the way between the two shoulders 7 at the periphery of the 
shell 2. 
The median portion of the internal space 17 of the shell 2 accommodates at 
least one row of primary hydrostatic bearing elements 8 which are adjacent 
the nip of the roll 1 with a second roll and are preferably assembled into 
two or more groups. By admitting a pressurized hydraulic fluid into, or by 
permitting hydraulic fluid to flow from, selected groups of primary 
bearing elements 8, an automatic control system can regulate the width of 
corresponding portions of the nip between the shoulders 7. The bearing 
elements 8 operate between the carrier 3 and the adjacent portions of the 
internal surface of the shell 2. 
The median portion of the internal space 17 of the shell 2 further 
accommodates at least one row of secondary hydrostatic bearing elements 9 
which are disposed substantially diametrically opposite the bearing 
elements 8 and are preferably assembled into two or more groups. By 
admitting pressurized hydraulic fluid into selected groups of secondary 
bearing elements 9, a control system can influence the width of the 
corresponding portion or portions of the nip between the shoulders 7 
bounding the axial ends of the external working surface 6 on the shell 2. 
Suitable hydrostatic bearing elements and controls therefor are disclosed, 
for example, in German Offenlegungsschrift No. 30 14 891 and in numerous 
United States and foreign patent and patent applications of the assignee 
of the present application. Reference may be had, for example, to U.S. 
Pats. Nos. 4,328,744, 4,389,933, 4,394,793, 4,520,723 and 4,625,637. 
Hydraulic fluid which is to be conveyed to selected bearing elements 8 
and/or 9 is stored in a suitable source here shown as a tank 19. A pump 10 
draws fluid from the tank 19 and delivers the fluid to supply conduits L1, 
L2 for the bearing elements 8 and to supply conduits L3, L4 for the 
bearing elements 9 (it is assumed here that the bearing elements 8 are 
assembled into two groups and that the bearing elements 9 are also 
assembled into two groups) by way of a system of valves 11. These valves 
control the pressure and the rate of flow of hydraulic fluid to selected 
supply conduits. The system of valves 11 has an input 12 for signals from 
a control unit (not shown) serving to select those groups of bearing 
elements 8, 9 which are to receive pressurized fluid or which are to be 
sealed from the heating device 13 and pump 10. 
The temperature of fluid which is supplied to the conduits L1 to L4 is 
determined by the intensity and/or other characteristics of signals which 
are transmitted to the input 14 of the heating device 13. The actual 
temperature of fluid leaving the heating device 13 is monitored by a 
sensor 15 which transmits signals to a second input 16 of the heating 
device 13. The latter intensifies or reduces the heating action upon fluid 
which is delivered by the pump 10 when the characteristics of signals at 
the input 14 deviate from those at the output 16. 
Each hydrostatic bearing element 8, 9 has at least one pocket which is 
adjacent the internal surface of the shell 2 and from which heated 
hydraulic fluid leaks into the median portion of the internal space 17. 
The central portion of the shell 2 is heated as a result of exchange of 
heat with fluid in the pockets of the bearing elements 8 an/or 9, and 
spent fluid which gathers in the internal space 17 of the shell 2 is 
returned to the source (tank) 19 by way of one or more radially extending 
channels 18 which are provided in the carrier 3 and connect the internal 
space 17 with a return conduit R1 serving to deliver spent fluid all the 
way to the source 19. 
It will be seen that hydraulic fluid which is used to operate the 
hydrostatic bearing elements 8, 9 serves as a means for delivering heat to 
the median portion of the shell 2. The bearing elements 8, 9 can be said 
to form part of a first heating device which further includes the device 
13, the pump 10, the system of valves 11, the conduits L1-L4 and R1, and 
the channel or channels 18 and serves to heat the median portion of the 
shell 2 to a desired temperature. 
The end portions 37 of the shell 2 are rotatable on antifriction or 
friction bearings 20 which surround the respective portions of the carrier 
3 and are adjacent the respective end faces of the shell. Since the very 
hot hydraulic fluid which is supplied by the conduits L1 to L4 is not 
suitable for use as a lubricant for the bearings 20, the roll 1 is 
provided with separate means for lubricating the bearings 20 with a 
lubricant having a temperature lower than that of hydraulic fluid which is 
used to heat the median portion of the shell 2. The lubricating means 
includes a source 25 in the form of a tank from which lubricant can be 
drawn by a pump 21. The pump 21 delivers lubricant to a supply conduit V 
by way of a cooling device 22. The conduit V delivers cooled lubricant to 
an annular chamber 23 which is adjacent the inner axial end of the bearing 
20. The thus supplied lubricant flows axially through the bearing 20 and 
gathers in a second annular chamber 24 at the outer axial end of the 
bearing. The chamber 24 is connected with the source 25 by way of return 
conduit R2. The illustrated pump 21 can be used to supply lubricant to the 
bearing 20 of FIG. 1 as well as to the bearing in the other end portion of 
the shell 2. However, it is within the purview of the invention to provide 
a discrete lubricating means for the bearing in the right-hand end portion 
of the shell 2. 
The bearing 20 in the end portion 37 which is shown in FIG. 1 is sealed 
from the median portion of the internal space 17 (i.e., from hydraulic 
fluid which leaks from the hydrostatic bearing elements 8 and 9 into the 
interior of the shell 2) by a composite sealing device 26 which is 
adjacent the chamber 23 and establishes a fluidtight seal between the 
internal surface of the shell 2 and the external surface of the carrier 3. 
The sealing device 26 includes two discrete sealing elements 27 and 28. 
The sealing element 27 has at least one flexible elastic lip adjacent the 
chamber 23 (i.e., adjacent the bearing 20), and the sealing element 28 has 
at least one flexible elastic lip adjacent the median portion of the 
internal space 17. Reference may be had to aforementioned U.S. Pat. No. 
4,757,584. 
A further sealing element 29 is provided to seal the chamber 24 for spent 
lubricant from the atmosphere. The sealing element 29 is installed between 
a ring 30 on the carrier 3 and a ring 31 which is secured to the end 
portion 37 of the shell 2. An annular seal fluid collecting space 32 is 
adjacent the rings 30 and 31 to collect lubricant (if any) which happens 
to leak beyond the sealing element 29 toward the left-hand end of the 
shell 2. A conduit 33 serves to convey leak fluid from the space 32 into 
the source 25 or into a separate receptacle. 
Each bearing 20 and the associated sealing device 26 together constitute an 
insert E which is installed in the respective end portion 37 of the shell 
2 adjacent the respective end face of the shell. Such inserts E interfere 
with heating of the end portions 37 so that, in the absence of any 
undertakings to the contrary, the effective axial length of the external 
surface 6 (and of the nip or nips which the surface 6 defines with the 
external surface or surfaces of one or more adjoining rolls) would be much 
less than the distance between the two shoulders 7. The extent to which 
the inserts E influence the temperature of the end portions 37 depends 
from the intensity of heating action upon the median portion of the shell 
2 (by the heating device including the hydrostatic bearing elements 8 and 
9) and also from the intensity of cooling action upon lubricant in the 
cooling device or devices 22. Thus, if the temperature of heated fluid 
which is supplied by the conduits L1 to L4 is very high and the 
temperature of lubricant which is delivered by the supply conduit V is 
much lower, the effective length of the external surface 6 of the shell 2 
will be much less than the distance between the shoulders 7, i.e., the 
actual length of the roll 1 will greatly exceed its effective length (the 
length of the nip or nips between the roll and one or more adjacent 
rolls). On the other hand, uniform heating of the shell 2 all the way 
between its end faces, or practically all the way between such end faces, 
is desirable and advantageous because this renders it possible to reduce 
the overall length of the roll and the width of the machine in which the 
roll is put to use. 
In accordance with a feature of the invention, the roll 1 is equipped with 
a discrete second heating device 34 which ensures that the temperature of 
the end portions 37 of the shell 2 matches or very closely approximates 
the temperature of the median portion of the shell so that the effective 
length of the nip or nips at the periphery of the roll 1 equals or 
approximates the distance between the shoulders 7. The heating device 34 
includes a plurality of axially parallel channels 35 and 36 in the form of 
bores or holes which are machined into or are otherwise formed in each end 
portion 37 of the shell 2 and each of which has an open end in the end 
face of the respective end portion 37. The channels 36 alternate with the 
channels 35 in the circumferential direction of the shell 2, and each 
channel extends along the full length of that portion of the shell which 
surrounds the respective insert E (including a bearing 20 and the adjacent 
sealing means 26). Threaded plugs 38 or other suitable sealing elements 
are provided to fluidtightly seal the open ends of the channels 35 and 36. 
A circumferentially extending channel 39 (see also FIG. 2) is provided 
adjacent the plugs 38 to connect the respective end portions of each pair 
of neighboring channels 35 and 36. 
That end portion of each channel 35 which is remote from the respective 
connecting conduit 39 is provided with a radially inwardly extending inlet 
40 for heated fluid, and that end portion of each channel 36 which is 
remote from the respective connecting channel 39 is provided with a 
radially inwardly extending outlet 41 serving as a passage for reception 
of spent fluid. The inlets 40 and the outlets 41 are outwardly adjacent a 
separable sleeve-like tubular section 42 of the shell 2 which surrounds 
the sealing means 26. As can be seen in FIG. 3, the tubular section 42 has 
radially extending bores 43 which constitute extensions of the inlets 40 
and are coplanar with the orifice of a nozzle 47 in the carrier 3. The 
tubular section 42 can be said to form part of a centrifugal pump 44 which 
serves to propel heated hydraulic fluid from the orifice of the nozzle 47, 
through successive extensions 43 of the tubular section 42, into the 
inlets 40 of the respective channels 35, thereupon through the channels 
35, 39, 36, and through the outlets or passages 41 of the channels 36 into 
the respective end portion of internal space 17 in the shell 2. Spent 
hydraulic fluid which is discharged by the outlets 41 is returned into the 
source 19 by the conduit R1. 
The stream of hydraulic fluid which is discharged by the pump 10 is divided 
into a first flow entering the heating means 13 and a second flow entering 
a discrete second heating means 45 analogous to the heating means 13, 
i.e., the heating means 45 also comprises two inputs, one for signals 
which denote the desired temperature of fluid flowing toward the channels 
35 and the other for signals which denote monitored temperature of such 
fluid ahead of a second system of valves 46 having an input for signals 
which control the rate and/or pressure of fluid flowing into the channels 
35. The system of valves 46 regulates the rate of admission of heated 
fluid into a supply conduit L5 which delivers heated fluid to the nozzle 
or nozzles 47 of the centrifugal pump 44. All extensions 43 and inlets 40 
are located in a common plane extending at right angles to the axis of the 
shell 2, and the orifice of each nozzle 47 is also located in such plane 
so that the nozzle or nozzles 47 can inject streamlets of heated fluid 
into successive extensions 43 when the tubular section 42 of the sleeve 2 
rotates with reference to the carrier 3. Streamlet(s) of pressurized 
hydraulic fluid which is (or are) discharged by the orifice(s) of the 
nozzle(s) 47 contributes or contribute to propelling action upon the fluid 
flowing in the channels 35, 36 and 39. The temperature of the end portions 
37 of the shell 2 can be regulated with a high degree of accuracy and 
within a wide range by appropriate adjustment of the valves 46 and heating 
means 45. 
The second heating device 34 renders it possible to greatly increase the 
effective length of the shell 2, and hence the effective length of the 
aforediscussed nip or nips, by the simple expedient of heating the end 
portions 37 (either entirely or in part) at least substantially 
independently of the heating means for the median portion of the shell. As 
a rule, the effective length of the shell 2 will include at least 50 
percent of the axial length of each insert E. At the very least, the 
effective length of the surface 6 will be that between the center of the 
illustrated bearing 20 and the center of the bearing in the other end 
portion 37 of the shell 2. In many instances the effective length of the 
improved roll 1 will be that between the shoulders 7 of the shell 2. 
The conduit V can supply heated fluid to the channels 35 in each end 
portion 37 of the shell 2. Alternatively, an additional second heating 
device 34 can be provided to ensure adequate heating of the right-hand end 
portion of the shell 2. 
An important advantage of the improved roll 1 is that the effective axial 
length of the shell 2 is not much less than, or even matches, the actual 
axial length of the shell. In addition, it is much simpler to adequately 
heat the median portion of the shell 2 by the primary or first heating 
device via conduits L1 to L4 because the transfer of heat from the median 
portion to the end portions 37 of the shell is minimal or nil. 
Another important advantage of the improved roll 1 is that its overall 
length can be reduced in comparison to that of conventional rolls which 
are without a discrete second heating device for the end portions of the 
shell. This is due to the fact that the effective axial length of the 
shell 2 more closely approximates or even matches the actual axial length. 
Therefore, the width of the frame for the improved roll 1 can be reduced 
accordingly with attendant drastic reduction of space requirements of the 
entire machine in which the improved roll is put to use. The overall 
length of a roll which is to cooperate with one or more additional rolls 
to define one or more nips of predetermined length, and which embodies a 
discrete second heating device for the end portions of its shell, is much 
less than the length of a standard roll wherein the end portions of the 
shell are heated only indirectly (by exchanging heat with the median 
portion) or are not heated at all. It is preferred to select the second 
heating device 34 in such a way that it adequately heats at least 50 
percent of the axial length of those portions of the shell 2 which 
surround the inserts E. As mentioned above, the heating action of the 
device 34 can be selected in such a way that the heating action is 
adequate all the way to the shoulders 7, i.e., along 100 percent of the 
axial length of those portions of the shell which surround the inserts E. 
An advantage of the pump 44 is that it prevents stagnation of hydraulic 
fluid in the paths leading to the channels 35 and from the channels 36. 
This enhances the predictability of heating action upon the end portions 
37 of the shell 2. The illustrated pump 44 relies on the action of 
centrifugal force upon the jets of fluid which issue from the orifice(s) 
of the nozzle or nozzles 47 and penetrate into the oncoming extensions 43 
of the inlets 40 leading to the respective ends of the heating channels 
35. 
The pump 44 operates satisfactorily even though the inlets 40 of the 
heating channels 35 are closely adjacent the passages or outlets 41 for 
evacuation of spent fluid from the channels 36. The reason is that the 
intake ends of the inlets 40 are located radially inwardly of the intake 
ends of channels or passages 41. Thus, the radial component of the flow of 
heated fluid into the channels 35 is greater than the radial component of 
the flow of spent fluid which leaves the channels 36. 
Each inlet 40 directly receives a jet or streamlet of pressurized hydraulic 
fluid from the orifice of the illustrated nozzle 47 once during each 
revolution of the shell 2 with reference to the carrier 3. In addition, 
each inlet 40 can receive pressurized fluid from the annular chamber which 
is located radially inwardly of the inlets 40 during each stage of each 
revolution of the shell 2. This ensures a practically uninterrupted flow 
of heated fluid into the channels 35. Direct propulsion of jets of hot 
pressurized fluid into the inlets 40 during each revolution of the shell 2 
ensures predictable circulation of such fluid along the paths which are 
defined by the heating channels 35, by the associated connecting channels 
39 and by the respective channels 36. If the carrier 3 is provided with 
two or more fluid-discharging nozzles 47, each inlet 40 directly receives 
two or more jets of pressurized heating fluid during each revolution of 
the shell 2. 
The channels 35, 36 need not extend into the main or median portion of the 
shell 2 because the median portion is adequately heated by fluid which is 
admitted to the hydrostatic bearing elements 8 and/or 9. As mentioned 
above, the channels 35 receive sufficient quantities of heated fluid 
because their inlets 40 are in direct alignment with the orifice of each 
nozzle 47 once during each revolution of the shell 2 and because the 
inlets 40 can receive heated fluid from the annular chamber which is 
adjacent the intake ends of extensions 43 during each and every stage of 
each revolution of the shell relative to the carrier 3. 
The outlets or passages 41 of the channels 36 are axially offset with 
reference to the inlets 40 and their extensions 43 so that heated fluid 
which is admitted by the orifice(s) of the nozzle or nozzles 47 cannot 
penetrate into the outlets 41 and thus cannot interfere with the flow of 
spent fluid from the channels 36 into the median portion of internal space 
17 in the shell 2. 
Cooling of the lubricant which is supplied to the bearings 20 of the 
inserts E by the pump 21 and conduit V is desirable and advantageous when 
the temperature of heated fluid which is supplied to the hydrostatic 
bearing elements 8 and 9 is in excess of 250.degree. C., e.g., between 
250.degree. and 350.degree. C. As a rule, the lubricant (e.g., oil) for 
standard antifriction or friction bearings cannot stand such elevated 
temperatures. The cooling device 22 ensures that the temperature of 
lubricant which is admitted to the bearings 20 of the inserts E does not 
rise above a predetermined maximum acceptable value. 
The bearings 20 are disposed outwardly of the respective sealing means 26. 
This is desirable and advantageous because the sealing means 26 are less 
sensitive to elevated temperatures than the lubricant which is supplied to 
the bearings 20. Thus even though cooling of lubricant for the bearings 20 
could prevent adequate heating of the respective parts of the end portions 
37, the second heating device 34 invariably ensures adequate heating of 
those parts of the end portions 37 which surround the sealing means 26. 
This guarantees that the effective length of the shell 2 is not less than 
that between the two bearings 20, even under the most adverse 
circumstances when the cooling of lubricant for the bearings 20 presents 
adequate heating of adjacent parts of the end portions 37. It has been 
found that, at least in many instances, cooling of lubricant for the 
bearings 20 does not prevent the second heating device 34 from properly 
heating the entire end portions 37 of the shell 2, i.e., all the way to 
the shoulders 7. 
The purpose of sealing means 26 is to prevent a mixing of lubricant for the 
bearings 20 with hydraulic fluid which is supplied to the channels 35 and 
hydrostatic bearing elements 8 and 9. Though the sealing means 26 
contribute to axial length of the inserts E, and hence to the axial length 
of the roll 1, such increase of axial length is warranted in view of the 
beneficial effect of sealing means 26 upon the quality of lubricant for 
the bearings 20 and upon the quality of hydraulic fluid for admission into 
the channels 35 and hydrostatic bearing elements 8, 9. Moreover, the 
second heating device 34 ensures that the end portions 37 of the shell 2 
are adequately heated in spite of increased axial length of the inserts E 
due to the provision of sealing means 26. It has been found tht the 
provision of sealing means 26 with plural lips, one of which is adjacent 
the respective bearing 20 and the other of which is adjacent the median 
portion of internal space 17 in the shell 2, ensures a highly satisfactory 
separation of hydraulic heating fluid from cooled lubricant to thus 
prevent contamination and/or overheating of lubricant by the hydraulic 
fluid and/or contamination and/or cooling of hydraulic fluid by the 
lubricant. 
FIGS. 4 to 6 show a portion of a modified roll 101. Many parts of this 
modified roll which are identical with or clearly analogous to 
corresponding parts of the roll 1 are denoted by similar reference 
characters plus 100. 
The second heating device 134 of the roll 101 has heating channels 135 and 
136 in the form of axially parallel grooves which are provided in the 
peripheral surface of an inner tubular section 142 forming a separately 
produced part of the respective end portion 137 of the shell 102. The 
outer tubular section of the end portion 137 is integral with the median 
portion of the shell 102. Those end portions of pairs of neighboring 
channels 135, 136 which are adjacent the end face of the respective end 
portion 137 of the shell 102 communicate with each other by way of a 
circumferentially extending connecting channel 139 which is a groove 
machined into or otherwise formed in the peripheral surface of the inner 
tubular section 142. The length of the inlets 140 of heating channels 135 
(in the radial direction of the shell 102) considerably exceeds the length 
of fluid discharging outlets or passages 141 of the channels 136. This 
results in the provision of a centrifugal pump 144. The outlets 141 
discharge spent hydraulic fluid into the internal space 17 of the shell 
102, and the inlets 140 receive heated hydraulic fluid from the orifice or 
orifices of one or more nozzles 47 in the carrier 3. 
An advantage of the roll 101 is that the making of grooves or channels 135 
and 136 in the peripheral surface of the inner tubular section 142 of each 
end portion 137 of the shell 102 (e.g., in a milling machine) is a 
relatively simple and inexpensive operation. Moreover, the weight of an 
inner tubular section 142 is a small fraction of the weight of a shell 
102; this also contributes to lower cost of the making of grooves or 
channels 135, 136 and 139 (as compared with the cost of drilling bores or 
holes in the end faces of the shell 2 in order to form the channels 35, 36 
which are shown in FIGS. 1 to 3). 
FIGS. 7 and 8 show a portion of a third roll 201. Many parts of this roll 
which are identical with or clearly analogous to corresponding parts of 
the roll 1 of FIGS. 1 to 3 are denoted by similar reference characters 
plus 200. The roll 201 constitutes a modification of the roll 101 because 
each end portion 237 of the shell 202 comprises an outer tubular section 
which is integral with the median portion of the shell and an inner 
tubular section 242 which is a separately produced part and has a 
peripheral surface provided with axially parallel heating channels 235 
having radially extending inlets 240 at those ends which are remote from 
the respective end face of the shell 202. The outlets 241 for the channels 
235 are provided in the ring 231 and serve to deliver spent fluid into an 
annular evacuating chamber 248 having at least one outlet connected to a 
conduit (not specifically shown) which returns the fluid to the source 19. 
The carrier 3 is provided with one or more nozzles 47 having orifices which 
discharge heated fluid into the inlets 240 of successive heating channels 
235 when the shell 202 rotates relative to the carrier. 
A radially extending partition 249 is provided in the shell 202 to seal the 
median portion of the internal space 17 from the outer portion of such 
space, namely from the portion which accommodates the insert E in the 
respective end portion 237 of the shell 202. The nozzle or nozzles 47 
actually deliver heated fluid into an annular chamber between the internal 
surface 250 of the tubular section 242 and the adjacent portion of the 
peripheral surface of the carrier 3. Heated fluid which is discharged by 
the nozzle or nozzles 47 is acted upon by centrifugal force so that it 
tends to flow radially outwardly and enters the innermost portions of 
inlets 240 in the internal surface 250 of the tubular section 242. 
Centrifugal force reduces the likelihood of extensive flow of heated fluid 
from the nozzle or nozzles 47, along the partition 249 and into the median 
portion of the internal space 17. 
An advantage of the roll 201 is the simplicity of the second heating device 
234. Thus, spent fluid which reaches the left-hand ends of the heating 
channels 235 simply flows into the evacuating chamber 248 (the left-hand 
axial end of each channel 235 is open) which is adjacent the respective 
axial end of the shell 201 and is readily connectable with a conduit for 
return flow of spent fluid into the source 19. 
The partition 249 ensures that the annular chamber which is surrounded by 
the internal surface 250 of the tubular section 242 of the illustrated end 
portion 237 of the shell 202 is invariably filled with a supply of heated 
fluid which flows into the inlets 240 of the channels 235 under the action 
of centrifugal force during each and every stage of each revolution of the 
shell 202 about the carrier 3. 
FIG. 9 shows a portion of a calendar or an analogous machine wherein a roll 
301 cooperates with a second roll W to define an elongated nip for a web 
of paper, plastic, textile or other material. The median portion of the 
shell 302 of the roll 301 is or can be heated in the same way as the roll 
1 of FIGS. 1 to 3. However, the second heating device 334 comprises two 
stationary inductive heaters 335, 336 which are outwardly adjacent the 
respective end portions 237 of the shell 302. Each of the heaters 335, 336 
can comprise an electromagnet which is connected to a source of 
alternating current and serves to generate, by induction, eddy currents in 
the respective end portions 337 of the shell 302. The latter is made of 
steel. Such mode of heating also ensures that the temperature of the end 
portions 337 will match or closely approximate the temperature of 
hydraulically heated median portion of the shell 302. 
The inductive heaters 335, 336 can be installed on and can rotate with the 
respective end portions 337 of the shell 302. This does not present 
problems when the machine which embodies the rolls 301, W of FIG. 9 is in 
actual use because, in many instances, the effective width of the web 
which is caused to advance through the nip of rolls in a calender or in a 
like machine is much less than the axial length of the rolls. 
Inductively heated rolls are disclosed, for example, in German 
Offenlegungsschrift No. 33 40 683. 
FIGS. 10 to 12 show a portion of a fourth roll 401. Many parts of this roll 
which are identical with or clearly analogous to corresponding parts of 
the roll 1 of FIGS. 1 to 3 are denoted by similar reference characters 
plus 400. The main difference between this embodiment and the previously 
described embodiments is that the second heating device 434 includes 
component parts of the inserts E, namely annular hydrostatic radial 
bearings 450 and annular hydrostatic axial or thrust bearings 451 for the 
respective end portions 437 of the shell 402. The means for supplying 
heated hydraulic fluid to the illustrated radial bearing 450 comprises a 
conduit L6 in the carrier 3, and the means for supplying heated hydraulic 
fluid to the illustrated axial bearing 451 comprises a conduit L7 in the 
carrier. 
The radial bearing 450 comprises an outer bearing ring 452 and an inner 
bearing ring 456 within the outer bearing ring. The peripheral surface 453 
of the outer bearing ring 452 has two annuli of pockets 454 which are 
adjacent the respective outer portion of the internal surface of the shell 
402. The outer bearing ring 452 has a spherical (concave) internal surface 
455 which abuts the adjacent spherical (convex) external surface of the 
inner bearing ring 456. The two spherical surfaces define an annular fluid 
distributing chamber 457 which receives heated fluid from radially 
extending channels 458 in the inner bearing ring 456 and discharges heated 
fluid into the pockets 454 by way of fluid throttling passages 459 in the 
outer bearing ring 452. The fluid distributing chamber 457 can consist of 
an annulus of discrete recesses or depressions in the spherical internal 
surface 455 of the outer bearing ring 452 and/or in the spherical external 
surface of the inner bearing ring 456. 
The channels 458 receive heated fluid from the conduit L6 in the carrier 3. 
These channels are disposed in a common plane which is normal to the axis 
of the shell 402 and also includes the discharge end of the conduit L6. 
Heated fluid which flows from the conduit L6 into the channels 458 and 
thence into the chamber 457 on its way into the pockets 454 via throttling 
passages 459 leaks along the external surface 453 of the outer bearing 
ring 452 and enters the median portion of the internal space 17 or an 
annular fluid evacuating chamber 460 whence it flows into a conduit R3 
serving to return spent fluid into the source 19. The pockets 454 in the 
peripheral surface 453 of the outer bearing ring 452 can be assembled into 
one, three or more annuli. 
The hydrostatic axial bearing 451 which is shown in FIGS. 10 and 12 
comprises a ring-shaped member 461 (hereinafter called wall) which is 
affixed to the internal surface of the respective end portion 437 of the 
shell 402. This wall is disposed between and is rotatable relative to two 
thrust bearing rings 462, 463 surrounding a ring-shaped barrier 472 on the 
respective end portion of the carrier 3. The bearing rings 462, 463 have 
radially extending surfaces 464 which abut the respective sides or 
surfaces of the wall 461 and are provided with annuli of pockets 465 (see 
particularly FIG. 12) for reception of heated fluid which heats the wall 
461 and hence the respective end portion 437 of the shell 402. Each pocket 
465 (each of the bearing rings 462, 463 is assumed to have six identically 
dimensioned and configurated pockets) is an arcuate recess in the surface 
464 of the respective bearing ring. The pockets 465 alternate with 
radially extending channels 466. 
The bearing rings 462, 463 have spherical (convex) surfaces 467 which abut 
complementary spherical (concave) surfaces of neighboring supporting rings 
468, 469 traversed by channels 470. The receiving ends of the channels 470 
communicate with the outlet of the supply conduit L7 in the carrier 3. The 
bearing rings 462 and 463 are provided with throttling passages 471 
defining paths for the flow of heated fluid into the respective sets of 
pockets 465. 
The supporting rings 468, 469 are integral with or are rigidly connected to 
the aforementioned ring-shaped barrier 472 which is surrounded by a 
substantially sealed inner annular chamber 473. The arrangement is 
preferably such that the barrier 472 has two mirror symmetrical halves one 
of which is integral with the supporting ring 468 and the other of which s 
integral with the supporting ring 469. The inner annular chamber 473 
communicates only with the aforementioned radial channels 466 which 
alternate with the pockets 465 of the bearing rings 462 and 463. The outer 
ends of the channels 466 communicate with outer annular chambers 474 and 
460 which, in turn, communicate with a return conduit R3 in the carrier 3. 
Heated hydraulic fluid which is admitted into the pockets 465 leaks along 
the respective sides of the wall 461 and enters the channels 466 to flow 
into the outer annular chambers 460, 474 and thence into the source 19 by 
way of the conduit R3. Such mode of establishing paths for the flow of 
heated fluid ensures a highly satisfactory exchange of heat between the 
fluid and the wall 461 which, in turn, exchanges heat with the respective 
end portion 437 of the shell 402. The fluid also heats the ring 431 which 
exchanges heat with the respective end portion 437 in immediate proximity 
of the respective shoulder 7 in the external surface 6 and of the 
respective end face of the shell 402. 
An advantage of the roll 401 is that the end portions 437 of the shell 402 
can be heated to elevated temperatures because the radial bearings 450 
and/or the axial bearings 451 can transmit large quantities of heat in a 
highly predictable manner. Moreover, heated fluid which is supplied via 
conduits L6 and L7 serves the dual purpose of lubricating the bearings 
450, 451 and of heating the end portions 437 of the shell 402. Each of the 
bearings 450, 451 defines for the heated fluid paths which extend along 
the internal surface of the shell 402 and/or along the internal surfaces 
of parts (such as 431 and 461) which are in intimate contact with the 
shell to thus ensure a highly satisfactory exchange of heat. 
The radial bearings 450 exhibit the advantage that they deliver heated 
fluid into direct contact with the shell 402 because the pockets 454 are 
provided in the peripheral surface 453 of the outer bearing ring 452 which 
is immediately adjacent the respective end portion 437 of the shell. The 
spherical surfaces 455 enable the end portions 437 of the shell 402 to 
change their inclination with reference to the carrier 3 in response to 
admission of pressurized fluid into one or more groups or sets of 
hydrostatic bearing elements 8 and/or 9. Still further, delivery of heated 
fluid to the pockets 454 necessitates the provision of relatively simple 
fluid supplying or conveying means. 
The axial hydrostatic bearings 451 exhibit the advantage that the walls 461 
can practically pinpoint the delivery of heat to selected portions of the 
internal surface of the shell 402 within the respective end portions 437. 
The annular chamber 473 serves to gather heated fluid which flows radially 
inwardly from the pockets 465, and the thus gathered fluid heats the 
adjacent portions of the bearing rings 462, 463 to thus increase the 
quantity of heat which is transferred form the rings 462, 463 to the wall 
461 and thence to the respective end portion 437 of the shell 402. As 
already explained above, the inner annular chamber 473 is substantially 
sealed and can deliver fluid only to the channels 466 which deliver the 
fluid to the outer annular chambers 460 and 474 in order to directly heat 
the end portion 437 and the ring 431, respectively. The provision of 
radial channels 466 between the pockets 465 of the bearing rings 462, 463 
contributes to simplicity and lower cost of the axial bearing 461. 
The supporting rings 468, 469 cooperate with the respective bearing rings 
462, 463 to enable the end portions 437 of the shell 402 to change their 
inclination with reference to the adjacent portions of the carrier 3 
because the surfaces 467 between the supporting rings 468, 469 and the 
respective bearing rings 462, 463 are spherical surfaces. Moreover, the 
supporting rings 468, 469 define channels 470 for heating fluid which is 
supplied by the conduit L7. 
The improved roll is susceptible of many additional modifications without 
departing from the spirit of the invention. For example, the illustrated 
second heating devices can be replaced with other suitable heating 
devices. In addition the second heating device 334 of FIG. 9 can be used 
in conjunction with the second heating device 34, 134, 234 or 434. Still 
further, the first heating device (for the median portion of the shell) 
need not. necessarily include the hydrostatic bearing elements 8 and/or 9 
but can include channels in the median portion of the shell and/or 
electrical heating means. These are but a few examples of possible 
modifications which will occur to those having the required skill in the 
art. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic and specific aspects of our contribution to 
the art and, therefore, such adaptations should and are intended to be 
comprehended within the meaning and range or equivalence of the appended 
claims.