Screw lifter screw technology

In general, the most suitable material for rolling is difficult to cut, and vice versa. Screw rolling relies on the plasticity of the substrate, ie the deformability of the substrate, in order to permanently press the shape of the roller against the blank of the workpiece. The good plasticity of the material to be cut usually results in the formation of colloidal chips and the formation of built-up edge on the tool. For example, cast iron does not have proper flow characteristics and therefore is not suitable for screw rolling.
The blank material is plastically deformed due to the pressure during the rolling of the screw rod, so it will have a minimum elongation of 5% and a maximum tensile strength of 246,000 psi.
In the screw rolling operation, a roller carrier is mounted on the workpiece in the axial, tangential or radial direction. Although each roller carriage uses the same basic operating principle, different screw machining applications require different approaches to the workpiece blank. This article will introduce three kinds of screw rolling ways in detail later.
Assuming that the workpiece material satisfies the rolling yield and flow requirements, the rolling process has several advantages over screw cutting. Compared with other production methods, the physical properties of the rolled rods are improved. Cold working is used in the screw rolling process, which increases the tensile strength and improves the surface finish compared to the cutting operation.
As with many cold working operations, the metal matrix of the workpiece blank is initially compressed by the force of the mold to yield plastically and produce the shape of the mold. The screw rolling operation is largely the same. The shape of the roller in the screw roller head forms a screw shape in the workpiece blank.
The compression of the base material causes the work to harden due to the compression of the metal matrix. It will produce fatigue resistance in the screw. This hardened state is part of the process, so any subsequent heat treatment of the rolling screw will have an annealing effect. Screw rolling should be performed after the heat treatment. Conversely, turning and grinding can be done before or after hardening, allowing the metal matrix to produce the desired shape and leaving the metal particle structure virtually intact.