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Polymer Processing Operations
Published in Nicholas P. Cheremisinoff, An Introduction to Polymer Rheology and Processing, 1993
Rubber calenders consist of two or more hardened and accurately machined metal rolls rotating in bearing journal boxes which are set in rugged iron frames. At least one roll is equipped with screwdowns to control the thickness of the processed material. Adjacent pairs of rolls rotating in opposite directions form a “nip”, in which the material being processed is squeezed into sheets or is laminated to form the desired product. The drives for the rolls include constant or variable-speed motors and reduction gearing to achieve roll surface speeds required by the processing requirements of the materials. A calender, depending on the number and the design of its rolls, is capable of sheeting, frictioning, coating, profiling, and embossing. A variety of roll configurations, both horizontally and vertically, are available in sizes ranging from laboratory units to commercial designs weighing tons. However, the three-roll vertical calender with 24-in. (diameter) x 68-in. (face length) rolls and the 4-roll “Z” and “L” with 28-in. × 78-in. rolls are typical of the machines used for mass production of tires, belting, sheeting, and similar articles. Three-roll calenders have been widely used for processing of mechanical rubber goods. Four-roll calenders are popular in tire plants. The four rolls permit simultaneous application of rubber compound on both sides of tire cord fabrics. Two-roll calenders are used to produce strips and profiles, often in combination with extruder feeding, in which case they are commonly referred to as “roller dies”.
Moving from Challenging Showstoppers to Innovative Solutions
Published in Rantanen Kalevi, Conley David W., Domb Ellen R., Simplified TRIZ, 2017
Rantanen Kalevi, Conley David W., Domb Ellen R.
A supercalender is a machine that smooths paper at the end of a paper-manufacturing process. More specifically, it is a set of rotating rollers stacked on top of each other. It is big, the size of a small multistory building. The system contains two kinds of rollers. One roller is made of metal, the other of a metal core with a soft outer layer. The paper is moved between many pairs of the metal and soft rollers. The pressure between rollers makes the paper smooth. In principle, the calender works as a mangle (a machine for ironing laundry by passing it between heated rollers), only it smooths paper instead of clothing or cloth.
Analyzing physical characteristics and shielding efficiency for non-lead medical radiation shielding sheets improved using PMMA
Published in Radiation Effects and Defects in Solids, 2019
Seon Chil Kim, Jeong Ryeol Choi
For shielding sheets producible for commercial purposes, the use of a calender process, rather than molding by a press which is known as to be expensive, is advantageous in the mass production of low intensity radiation shielding sheets. In the existing calender processes, shielding materials injected in base polymer materials without the degradation of tensile strength are usually less than 20%. The best solution for this problem may be improving it with the use of PMMA which acts as a material for enhancing the quality of products.