Calender and method of operating the same

Claim 3

A method as defined in claim 1, in which for separating said rolls from each other the direction of said first hydraulic force is reversed substantially simultaneously with the relieving of said second force and at least said highest roll is thereby moved upwardly from the lower rolls by said reversed first force.

Claim 4

A method as defined in claim 2, in which for separating said rolls from each other the direction of said first hydraulic force is reversed to lift at least said highest roll from the lower rolls shortly before said second force is relieved from said lowest roll.

Claim 5

A calender comprising a plurality of substantially horizontal rolls substantially vertically above each other and normally engaging by gravity upon each other, bearing means for each of said rolls slidable in a substantially Vertical direction, at least one first hydraulic unit having an upper cylinder and a piston slidable in said cylinder, and having a piston rod connected to said bearing means of the highest of said rolls, first hydraulic pressure supply means connected to said upper cylinder for normally pressing said upper piston from above upon said bearing means of said highest roll, at least one second hydraulic unit having a lower cylinder and a piston slidable in said cylinder between a normal upper end position and a lower end position and connected to said bearing means of the lowest roll, pressure release means for releasing the pressure from said lower cylinder when said rolls are to move downwardly so as to be separated from each other and when said rolls at least due to their gravity then press said lower piston from said upper end position to said lower end position, adjustable stop means associated with said bearing means of at least all lower rolls below said highest roll for limiting the distance of the downward separating movement of each of at least said lower rolls independently of the other rolls, second hydraulic pressure supply means connected to said lower cylinder for hydraulically moving said lower piston only in its upward direction for lifting at least said lower rolls and their bearing means from their separated positions to their normal operating positions, fixed stop means for preventing said lowest roll from being moved upwardly by said lower piston beyond its normal operating position, and control means for each of said pressure supply and release means.

Claim 6

A calender comprising a plurality of substantially horizontal rolls substantially vertically above each other and normally engaging by gravity upon each other, bearing means for each of said rolls slidable in a substantially Vertical direction, at least one first hydraulic unit having an upper cylinder and a piston slidable in said cylinder, and having a piston rod connected to said bearing means of the highest of said rolls, first hydraulic pressure supply means connected to said upper cylinder for normally pressing said upper piston from above upon said bearing means of said highest roll, at least one second hydraulic unit having a lower cylinder and a piston slidable in said cylinder between a normal upper end position and a lower end position and connected to said bearing means of the lowest roll, pressure release means for releasing the pressure from said lower cylinder when said rolls are to move downwardly so as to be separated from each other and when said rolls at least due to their gravity then press said lower piston from said upper end position to said lower end position, adjustable stop means associated with said bearing means of at least all lower rolls below said highest roll for limiting the distance of the downward separating movement of each of at least said lower rolls independently of the other rolls, second hydraulic pressure supply means connected to said lower cylinder for hydraulically moving said lower piston only in its upward direction for lifting at least said lower rolls and their bearing means from their separated positions to their normal operating positions, fixed stop means for preventing said lowest roll from being moved upwardly by said lower piston beyond its normal operating position, and control means for each of said pressure supply and release means.

Claim 7

A calender as defined in claim 4, in which said fixed stop means consist of a stop member which is secured to said lower cylinder and prevents said lower piston from being moved upwardly beyond said upper end position in which said lowest roll is in its normal operating position.

Claim 8

A calender as defined in claim 4, in which the length of the stroke of said lower piston is at least equal to the total width of the gaps between all of said rolls when seprated to the maximum extent from each other.

Claim 9

A calender as defined in claim 4, in which said upper piston is movable hydraulically in both directions in said upper cylinder and divides said upper cylinder into a first cylinder chamber and a second cylinder chamber, said first pressure supply means being adapted to be connected to and disconnected from said first chamber, third hydraulic pressure supply means adapted to be connected to and disconnected from said second chamber, second pressure release means for releasing the pressure from said second chamber when said first pressure supply means are connected to said first chamber, and third pressure release means for releasing the pressure from said first chamber when said third pressure supply means are connected to said second chamber and when substantially at the same time said second pressure supply means are connected to said lower cylinder.

Claim 10

A calender as defined in claim 7, in which said first pressure supply means for said first supply comprises a first pump, and said second pressure supply means for said lower cylinder and also said third pressure supply means for said second chamber comprise a second pump, said control means comprising valve means for alternatively connecting said second pump either to said lower cylinder or to said second chamber.

Claim 11

A calender as defined in claim 8 in which said first pressure release means for said lower cylinder comprise a release valve, said control means further comprising a control device for opening said valve to release the pressure from said lower cylinder only when the pressure produced by said upper piston in said second chamber exceeds a certain minimum value.

Claim 12

A calender as defined in claim 9, in which said control device comprises a cylinder and piston unit having a cylinder connected by a line to said second chamber, and a piston slidable in said cylinder and adapted to open said release valve when the pressure in said second chambeR exceeds said minimum value.

Claim 13

A calendar as defined in claim 10, in which said second pressure release means comprises a solenoid valve connected by a line to said second chamber and adapted in one operative position to remain closed regardless of the pressure in said second chamber and in its other operative position to be opened when the pressure in said second chamber exceeds a certain value.

Claim 14

A calender as defined in claim 7, in which said control means further comprise adjustable means for limiting the upward stroke of said upper piston.