Roughing rolling

Lubrication of sheet and strip is necessary for aU operations. Although for special operations vegetable and mineral oUs maybe employed, a mixture of paraffin and taUow oU is normally preferred in rough rolling. Requirements for finish-roll lubricant are more strict because of staining caused by breakdown of the oU or reaction with the zinc. Strip zinc is usuaUy finish-rolled with cotton seed or mineral oU. 

Vor-walzwerk, n. Metal.) roughing rolls, -wand, m. pretext, pretense, -warmapparat, m. preheating apparatus, fore warming apparatus. 

Roughing rolling Multi-stands or multi-passes Up to 40% reduction at one pass [127] 0-2 stands 1100-1150°C No... 

Zinc sheet is produced by the pack-rolling process, in which 2—40 rough-roUed sheets are stacked together in packs and roUed simultaneously. Packs must be spUt frequentiy, interchanging inner and outer sheets to equalize temperatures and reductions. With care, good quaUty sheets can be produced by this technique but considerable variations in properties can occur. If a bright ductile product is desired, roUs are held at 120—150°C the reduction on the last pass is 20—40%. 

Semi-finished products are first heated in a re-heat furnace until they are red hot (around 1200 C). On all types of mill the semi-finished products go first to a roughing stand. A stand is a collection of steel rolls (or drums) on which pressure can be applied to squeeze the hot steel passing through them, and arranged so as to form the steel into the required shape. The roughing stand is the first part of the rolling mill. The large semi-finished product is often passed... 

Over rough surfaces, an opposite effect, not easily measured in the laboratoiy, becomes apparent to the rider. A tire inflated to veiy high pressures (for example, 120 pounds) bounces off the peaks of the road surface, making the bike harder to control, and negating any theoretical decrease in rolling resistance. For... 

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