The process principle of cold rolling and the advantages and disadvantages

Cold rolling process is a new technology of less, no cutting, because of the precision cold rolling capacity maximum make the shape of the workpiece shape close to finished products and precision parts and precision, and can significantly improve the immanent quality of workpiece, all countries in the world in the commitment to the development of cold rolling technology research, and has set up a practical application in mass production. Such as British FORMFIO company cold rolling production line, the German SKF of EMB closed forming broaching machine production line of cold rolling, the German treasure fly screw ( Bud carried) Of URWA full-automatic bearing ring cold rolling machine, the Japanese co-prosperity of CRF type cold rolling machine, etc. , the German and Japanese equipment in domestic bearing industry has a small amount of introduction. Although many domestic enterprises focus on cold rolling technology continues to increase, but subject to raw material quality, weight and the precision of the blank, cold rolling process and the lack of cost-effective equipment, the bearing ring cold rolling technology has been unable to used widely, so understanding the working principle, process of cold rolling as well as the advantages and disadvantages of existing, help enterprise to make the right choice of the application of cold rolling. A, 1, the working principle of cold rolling precision cold rolling technology is at room temperature to annular rotary parts using extrusion and plastic deformation of the finished products were obtained a cold forming method. Cold rolling work motivation is driven by a main forming rolling wheel to forming the surface shape, a follower of molding mandrel to inner surface shape, forming mandrel and workpiece by the support roller bearing, rolling workpiece, rolling wheel to drive the workpiece rotation, mandrel with feed unit solid union support roller extrusion under the impetus of the workpiece, so as to realize the workpiece rolling. Phase 2, cold rolling analysis in the process of cold rolling, the rolling pressure is not a constant, with the feeding schedule change, has obvious periodic, cold rolling pressure and stroke relations in general can be divided into three stages: the first stage of Ⅰ - — Compression deformation stage. Rolling, supporting wheel mechanism started feeding, rolling pressure must overcome the inside of the metal deformation resistance and friction between billet and mold, make all the metal lattice is completely compaction, metal material to produce plastic deformation, rolling pressure increased sharply. The first Ⅱ stage - — Stable deformation stage. Support roller institutions continue to feed, force the metal continue to flow. In this stage, only change the height of billet, the stable deformation area, the plastic deformation zone height does not change with time, pressure does not change according to the schedule, so it is called in this stage of plastic deformation zone height called steady plastic deformation zone height. The height is according to when the rolling pressure reaches a certain minimum value, and only can produce stable deformation principle to determine. The first Ⅲ stage - — When the residual thickness of the blank exceeds stability after deformation zone height, such as supporting wheel institutions continue to move forward, rolling pressure and rising sharply. Known from the analysis of the above, at the end of the second phase, if you continue rolling, pressure is increased dramatically. Therefore, at this time must end rolling, otherwise the mould or rolling machine is damaged more easily.