Abstract: A packing sheet is formed on a calender having a rotatable large diameter heated cylinder and a rotatable smaller diameter unheated cylinder, with a gap between the cylinders, by feeding a preformed mixture of rubber material, fiber and solvent into the gap between the cylinders while the cylinders are rotating in opposite directions to form on the circumference of the large diameter cylinder a layer of progressively increasing thickness of the mixture during successive rotation of the cylinders. While the cylinders are thus rotating, heat from an external heat source is applied to the outer surface of the layer of material on the large diameter heated cylinder so that the material is heated both by heat from the large diameter heated cylinder and heat from the external heat source and is thereby vulcanized to form a cylindrical packing sheet. The cylinders are then stopped, the packing sheet is cut lengthwise of the cylinder and is stripped from the cylinder.

Abstract: A calender for producing packing sheets, in particular packing sheets reinforced with synthetic fiber, has a large diameter heated cylinder, on which a packing sheet is formed and vulcanized, rotatably supported by spaced calender stands and driven by a direct current motor. An unheated cylinder of smaller diameter also driven by a direct current motor, is supported by the calender stands for rotation and for movement toward and away from the heated cylinder and is hydraulically pressed toward the heated cylinder as a pressure roller. The circumferential speed of each of the cylinders is sensed by a pick-up activated by uniformly spaced marks on the circumference of the cylinder and the thickness of the packing sheet on the heated cylinder is sensed by sensing the position of the shaft of the pressure roller.

Abstract: A calender for producing packing sheets has a heated cylinder of large diameter and an unheated pressure cylinder of smaller diameter which is movable toward and away from the heated cylinder to vary the width of a gap between the cylinders. A plastic mixture plasticized by a solvent is fed to the gap between the cylinders and is formed into a sheet on the heated cylinder, where it is vulcanized. Two temperature sensors on a common support are positioned to measure the temperature of the outer surface of such sheet and transmit the temperature measurement to a procesor which is programmed to control operations of the calender. A further sensor measures the thickness of the sheet on the heated cylinder and the thickness measurement is transmitted to the processor as a further parameter in control of operation of the calender.