Parts which suitable for rolling is difficult for cutting, and vise versa. To stereotype shapes of roller into blanks,performance of the screw depends on the plasticity of materials,which also means its deformation property. Colloidal chip occurs as the high-plasticity of blanks process, which further turns into dander on cutter. For example, material of cast iron is eliminated from rolling process as it brings no suitable characteristics.
During processing, a roller carrier should be equipped in the axial, tangential or radial direction of workpiece.Even the same operating principle adopted for different carrier,different approach to workblank employed for the finished product applied to various place. This article will describe three screw rolling methods in detail.
Assuming that the material meets the rolling requirements,rolling process could bring greater benefit than screw cutting, which also bring a better physical characteristics to the screw. Rolling after refrigeration enhance its stretching ability and the smoothness of the surface.
Familiar with many cooling process, the metal matrix of the blank is initially compressed by the force of mold to plastically yield and produce the shape. Operation of screw rolling is largely the same. The shape of the rollers will form a screw shape in the blank.
Compression of metal matrix causes the contraction of blanks, which impose fatigue resistance to the screw. Such hardened state is a part of the process, any subsequent heat treatment will produce an annealing effect. Rolling implemented after heat treatment while turning and grinding can be done before or after hardening--metal matrix produces a desired shape with the structure of metal particle completely unchanged.