Note: Descriptions are shown in the official language in which they were submitted.
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POSITIO~ G MECHANIS~ FOR CALEIIDER ROLLS
Back~round of the Invention
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This invention relates to calenders and
super calenders of the type used to finish paper for
printing or other applications where a relatively
high smoothness is required. In such devices the
paper passes between the nip of a number of rollers
and by the circumferential friction of the rolls on
the paper surface a polishing action is obtained. The
rollers are generally arranged in a vertical stack.
Iron rolls alternate with paper filled rolls, that is,
rolls which are formed by placing a large number o~
doughnut-like paper disks on a co~mon shaft. These
paper ~illed rolls are largeLy responsible for the
polishing action. ~ ~
Paper filled rolls are easily dama~,ed in th~ -
event that there is a break in the paper web being
polished. I~hen the web breaks it bunches and jarlls
between the ni~s of the rollers causing unevenness on
the surface of the paper filled rolls impairing the
ability of such rolls to smooth the web evenly.
In an effort to avoid damage to paper filled
rolls when the web breaks and to permit adjustment of
the spacing between rolls, it is necessary to provide
some mechanism for positioning the rolls relative to
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each other and, in particular, for rapidly separating them
in the event of a break in the paper web or similar emergency
conditïon which couId damage the rolls. Such systems are ~ `
known in the prior art and, for example, see U. S. Patent Nos.
3,777,656, 3,948,166, and 3,584,570 which disclose lifting~
mechanisms. Although lifting mechanisms are Xnown, none of
them has the capability of rapidly separating the rolls~in
the event of an emergency condition and the capability of ;
automatically repositioning the rolls to their correct opera~
tive positions particularly when a worn paper roll has been ~ ;
replaced with a new roll of a different diameter.
It is accordingly an object of an aspect of the `
invention to provide an improved positioning mechanism for
calender rolls which is capable of accomplishing rapid separa~
tion of the rolls in an emergency situation. ;~
An object of an aspect of the invention is to provide
a device of the type described capable of automatically re-
positioning the rolls in their proper operative relation
regardless of changes in the roll diameter of the rolls in~
the calender stack.
An object of an aspect of the invention is to pro~
vide a hydraulic cylinder lifting mechanism for a super
calender which utilizes a lost motion connection to rapidly~
space the rolls one from the other in an emergency situation
by an amount determined by the lost motion elements.
An object of an aspect of the invention is to provide~
a hydraulic lowering mechanism for a calender stack which~ càn;~
rapidly separate the rolls in the stack by a preset amount~
to limit damage to the rolls in the event of a paper break~
According to one aspect of this invention there is;
provided a mechanism for vertically positioning a stack of~
calender rolls relative to a support frame, each roll being
mounted to the frame for movement in the vertical direction
comprising: (a) means for lifting and lowering the top rol1
of said stack, (b) means for lifting and lowering the bottom~
roll of said stack, (c) means for interconnecting the remain~
ing rolls of said stack, one to the other and to said top~
roll for movement with the latter, said interconnecting means
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including: ~i) piston and cylinder assemblies associated
with each of said remaining rolls, (ii) a lost motion connect-
ing means for interconnecting said assemblies one to the
other and to said top roll, (d) means for controlling opera-
tion of said assemblies to permit or prevent movement of thepistons relative to the cylinders, whereby when the pistons
are permitted to move the remaining rolls may be sequentially
lowered and automatically positioned in contact with each
other and said top and bottom rolls, and when the pistons
are prevented from moving, the rolls may be rapidly separated,
one from the other, by a distance determined by the lost
motion connecting means by lowering said bottom roll.
Other objects and advantages of the invention will
be apparent from the remaining portion of the specification.~ :
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Brief Description of the Drawings
Figure 1 is a side elevation view of a super
calender having the positioning mechanism according to
the invention provided therein.
Figure 2 is a front elevation of the super
calender of Figure 1.
Figure 3 is a sectional view along the lines
3-3 of Figure 2 illustrating the construction details
of the mechanism according to the invention in the
lowered position.
Figure 4 is a view si~ilar to Figure 3 illus-
trating the mechanism in the position in which the rolls
are spaced, one from the other.
Figure 5 is a schematic diagram illustrating
the operation of the hydraulic circuit for operating
the cylinders according to the invention.
Figures 6 and 7 are side elevational views o~
the bottom portion of the s~Lper calender illustrating
the bottom roll support mechanism in its raised and
lowered positions, respectively.
Figure 8 is an encl sectional view along the
line 8-8 of Figure 6.
Detailed Desc~iption
Referring to Figures 1 and 2, a super calender
machine for i~parting a smoothness to the surfaces of a
paper web is illustrated. The web 10 is drawn from a
roll 12 and passes through tension sensing rollers 14 to
a stack of calender rollers generally indicated at 16.
The web 10 passes back and forth between the nips of the
rollers, one of which is driven with the resulting
friction accomplishing the polishing action in a manner
well known to those skilled in the art. Fly rolls 18
areprovided to correctly position the paper web for
passage between the nips of the calender rolls. The
calender roll stack is formed of a combination of iron
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and paper filled rolls, the number and location of
each type being a function of the type of paper, the
smoothness desired and similar considerations. In any
case, a number of paper filled rolls will be included
in the stack and are subject to uneven wear or damage
in the event of a break or ~am in the web 10.
After passing through the nip of the bottom-
most pair of rollers the web leaves the calender stack
and is wound onto a take up reel 20.
To detect web jams and breaks, simple détection
mechanisms can be employed as, for example, an electrlc
eye to detect a paper break. If desired, a plurality of
such detectors may be employed. In the event of a break
or jam, it is necessary to rapidly separate the rolls,
one from the other, to avoid damaging the paper filled
rolls. During normal operation the rolls are under
pressure by virtue of hydraulic cylinders 23. When a
break occurs, cylinders 23 must remove pressure from
the rollers and begin lifting them in a manner to be
described. Simultaneously, a bottom roll is rapidly
lowered allowing the remaining rolls to drop do~nwardly
and separate until subsequently lifted by hydraulic
cylinders 23. If the separation occurs quickly enough
the paper web will not wedge between the nips of the
rollers and damage ~he paper filled rolls.
Figures 2 and 3 illustrate a plurality of
calender rolls 24 through 35 in a vertical stack. The
rolls are mounted on either end thereof to mountin~ ele~
ments 36 in the case of the topmost roll, elements 38
i.n the case of the in~ermediate rolls and to elements
40 in the case of the bottom roll. The mounting elements,
e~cept element 40, are slidably secured to vertical sup-
port colu~ns 42 on either end of the rolls permitting the
rolls to be moved vertically, as desired, to separate
the rolls or place them in contact for calenderin~. The
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uppermost roll 2~ is connected to the load and lift
cylinders 23 via the mounting elements 36. Mounting
elemen~s 38 are connected to the elements i~mediately
above it in the stack by means of a piston and cylinder
arrangement to be described in connection with Figure 3.
The bottommost roll 35 is, however, not connected to
other rolls. Instead, it is mounted for movement toward
and away from the remaining rolls in the stack by ele-
ments 40 described in connection with Figures 6 and 7.
A motor 4~ drives bottom roll 35 via a shaft 46 to
accomplish the calendering process in the usual manner.
Referring to Figure 3, the mounting elements
forming an integral part of the lifting mechanism of the
invention are illustrated. As seen in Figure 3, the
web 10 passes a first carrying roll 18 and then between
the nip of the topmost roll 24 and the roll 25. In the
illustrated embodiment roll 24 is preferably an iron
roll while roll 25 is a paper filled roll. As the paper
passes between the nip a polishing action occurs. As
the paper continues on its tortuous path through the
nips of the various rolls, additional polishing of both
sides of the web is accomplished.
In order to regulate the polishing action, it
is necessary that the rolls ~e properly compressed
during operation of the super calender. The bottom roll
35 is placed in the operative position (Figure 2) and
then the lift and load cylinders 23 àpply pressure to
the roll stack until the desired nip pressure is obtained.
In order to compress the rolls, they must be free to move
on the vertical column 42.
The mountin~ elements according to the invention
include a plurality of hydraulic cylinders 50 which are
interconnected one to the other. Each cylinder includes
an internal piston 52 (Fiuure 5) and connected thereto is
a piston rod 54 terminating in a rod eye 56. The rod
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eye has a generally rectangular opening 58 therethrough.
The bottom of ~he cylinder housing includes a clevis
58 having a generally circular opening designated 60.
The piston rod of one cylinder is connected to the
clevis 58 of the cylinder immediately above it in the
stack by means of a shaft or pin 62 which passes through
openings 58 and 60. The uppermost cylinders associated
with roll 25 have their piston rods secured to an open-
ing in the top mounting plate 36.
It will be understood that two sets of cylinders
50 of the type illustrated in Figure 3 are provided, one
set for each end o the rolls 25 through 34. The cylin-
ders 50 are secured to end plates 64 which receive rotat-
ably mounted shafts 66 on which the rolls are provided.
A portion of the end plates 64 are received in a channel
68 in the vertical columns 42 whereby vertical movement
of the calender rolls in the stack is obtained.
An important aspect of the present invention
is the manner in which t`he cylinders 50 are intercon-
nected one to the other. The pin 62, preferably cylin-
drical, has a flat portion 70 thereby reducing its
effective diameter in the vertical direction. The pin
is maintained in the position indicated in Figure 3 by
a loc~ing arrangement of any suitable type such as a
locking plate. Thus, the flat 7~ is always .acing up-
ward. It must engage the surface 72 of the rod eye
before a roll can be lifted from above. The reduction
in effective diameter of the pin 62 by providing flat ~
70 corresponds to a selected distance "d" by which the ~ ~.
30 rolls will be passed when they are separated for ~ ;~
emergency purposes ~Figure 4).
This arrangement constitutes a lost motion `~
connection intentionally provided in the stack for
the following purpose. ~1hen the stack is in the~posi-
tion indicated in Figure 3 it is being compressed by the~ ; :
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load and li~t cylinders 23. Should a paper break occur,
the load and lift cylinders will cease compressing, the
rolls and begin lifting the end plates 36 of the upper-
most roll. Simultaneously, the bottom roll 35 is rapidly
lowered, as will be descri~ed, permitting the in.ermediate
rolls to be separated, one from the other, by the amount
"d" of the lost motion connections. After separation the
lifting cylinders 23 raise t'ne stack in preparation for
resumption of super calendering.
The result of the separation of the stack is
clearly illustrated in Figure 4. It may be seen that
the rod eye associated with each roll is supported on
the pin 62 associated with the roll or mounting element
ne~t hlgher in the stack and that each of the illustrated
rolls are separated one from the other by a distance "d".
Referring now to Figure 5, a hydraulic circuit
for controlling each of the cylinders 50 is schematically
illustrated. Cylinder 50 includes an upper oil chamber
70, a lower chamber 72 with piston 52 being vertically
displaceable to alter the dimensions of chamber 70 and
72 thereby to move the piston rod 54 relative to the
cylinder housing 74. The up2er chamber 70 includes an
oil passage 76 while the lower chamber is provided with
a passage 78. Oil is supplied to the chambers by means
of the hydraulic circuit schematically indicated.
The circuit includes a solenoid valve 80
connected to the hydraulic line supplying fluid to the
upper chamber 70, a check valve 82 and a flow regulating
valve 84 in parallel therewith. The main oil line 86
supplies make up oil from a reservoir 88.
An important feature of the invention is the
pressurizing of the make up oil reservoir 88. This may
be accomplished using air pressure on the reservoir.
Alternatively, a low pressure hydraulic pump can be
employed and, in that case, reservoir 88 is unnecessary.
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The pressure is lo~, for example, 50 psi, although this
value is dependent upon the size and operating characteristics
of the cylinders. The pressure applied to the reservoir is
solely to prevent the weight of the rod and piston assembly
from eliminatin~ the gap "d" between the pin 62 and the rod
eye 56. I~hen the rolls are lowered to their operating posi-
tions the pistons are free to move. Nevertheless, it is
desired that the gaps "d" be maintained against the weight
of the piston rods. The pressure applied on the oil line
86 forces enough oil into the lower oil chambers 72 to
maintain these gaps.
Operation of the lifting mechanism of the present
invention is as follows. Assuming that the rolls are sepa-
rated due to an emergency, such as a paper break, the solenoid
valves 80 will be closed and the pistons locked in place.
This situation remains until the load and lift cylinders
raise the rolls fully. Valves 80 then open sequentially
lowering the rolls beginning with rolls 34. Lowering con- ~
tinues until all the pistons are at the top of the cylinders.
In this state roll change outs can be made as, for example,
where a roll is worn or dama~ed and needs to be replaced or
the equipment can be turned off without danger of causing
flat spots on the rolls. The valve ~0 is then closed again.
When it is desired to begin the calendering opera-
tion the rolls are placed in compression. The closed sole-
noid valves 80 permit oil to flow from the lower chamber 72
to the upper chamber 70 via check valve 82 and the check valve
portion of valve 80. Thus, roll 34 engages the bottom roll ;~
35 and displaces oil from chamber 72 into chamber 70. A
similar operation is then performed in sequence for each of
the rolls in the stack working from the bottom to the top.
In this manner the stack is automatically adjusted for the
current roll diameter. No manual adjustment of mechanical
elements is required.
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When the rolls are in contact with each other
they are ready to be compressed to a desired value.
The pressure from oil line 86 maintains sufficient up-
ward force on the piston 52 to insure that t'ne gaps "d'
between the pin and rod eye are maintained. I~hen the
process is complete the stack appears as illustrated in
Figure 3.
To separate the rolls the process is reversed.
During normal lifting the load and lifting cylinders 23
merely lift the top roll 24 which separates rolls 24 and
25 by the amount of the gap "d" and so on down the
stack. In the case of a separation due to a paper break,
etc., the bottom roll 35 is dropped by the mechanism
illustrated in Figures 6 and 7 rapidly separating the
in~ermediate rolls one from the other by the amount of
the lost motion connection. Simultaneously, the cylinder
23 begins the normallifting process.
Keferring now to Figures 6 and 7 J the mounting
elements 40 for the roll 35 are illustrated. The mount-
ing assembly supports the bottom roll 35 and moves itbetween raised and lowered positions. Figure 6 illus-
trates the raised position while Figure 7 illustrates
the lowered pOSitiOtl. The mounting elements include a
cylinder 90 having a piston rod 92. A clevis 94 is
pinned to a pair of links 96 and 98. Similarly, a
cylinder clevis 100 is pinned to a pair of links I02
and 104. As can be seen by comparing Figures 6 and 7,
when the piston is in an ex-tended position relative to
the cylinder the link pairs are in a substantially
vertical position, slightly over center, maintaining the
bottom roll bearing housing 106 and the associated sup-
port structure in a raised position. The over center
position maintains the raised position even in the event
of hydraulic pressure loss. As shown in Figure 7, when
the piston is retracted the links move inwardly lowering
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the bearing housing and support assembly. As indicated
in the drawings, the links connect the bearing housing
106 with a support base 108.
In order to maintain the roll 35 level, it is
necessary to insure that the links on each side move by
an equal amount. For that purpose the roller chain
arrangement indicated at 110 is provided. Pinned to the
co~.mection 112 between the bottom links and the base
108, for movement therewith, are sprocket wheels 113 and
115. A first roller chain 114 is pinned to the sprockets
113 and tension and link position are adjusted by turn
buckle 116. Similarly a second roller chain 117 is
pinned to sprockets 115. When the cvlinder 90 is
actuated to raise or lower the bottom roll 35, the chain
arrangement requires that both link pairs must move up
or do~ by an equal amount thereby maintaining the roll
in the proper position.
~ s previously indicated, during normal opera-
tion the bottom roll is maintained in the raised position
illustrated in Figure 6 whether or not the remaining
rolls in the stack are separated. In the event of an
emergency as, for example, a paper break, the cylinder
90 retracts the piston lowering the bottom roll 35,
which is a driven roll. This permits rapid separation
of the rolls as previously described herein.
While we have shown and described embodiments
of this invention in some detail, it will be understood
that this description and illustrations are offered
merely by way of example, and that the invention is to ~.
be limited in scope only by the appended claims.
