Stainless steel hexagonal screws can be screwed into al […]
Stainless steel hexagonal screws can be screwed into all malleable materials, that is, they can be screwed into materials that have the ability to plastically deform. The elongation rate of the material can be used as the basis. Generally, it is most suitable for materials with an elongation rate ≥8%~10%, but it is applicable even for cast alloys with an elongation rate <5%. However, for such materials, it should be passed The process verification determines the size of the optimized prefabricated hole and the use conditions such as moistening. Therefore, the materials that can be screwed in include non-alloy, low-alloy, aluminum and aluminum alloy (commonly used die castings), copper and copper alloy (copper content greater than 63%), and zinc and zinc alloy ( Commonly used die castings) and so on.
For those with poor plastic deformation performance or work hardening, such as stainless steel, gray cast iron and magnesium alloy, this type of stainless steel hexagonal screw can also be used under certain conditions of use.
For inapplicable materials or improper use conditions, chipping, seizure (or cold welding) and low roughness of the tapped screw hole may occur when the screw is screwed.
In order to ensure the quality of cold-extruded stainless steel hexagon screws, in addition to reasonable design of the mold structure, selection of high-quality mold materials and good heat treatment processes, the processing technology of mold parts is more important. For the upper punch, in addition to the higher requirements for dimensional accuracy and surface roughness, the cooperation with the combined concave mold puts forward higher requirements. If the fit is too tight, a dead mold is likely to occur. If the fit is too loose, the extrusion will The metal is easy to turn over from the extrusion surface, resulting in poor quality of the extrusion shape and the stainless steel hexagonal screw, and it is necessary to increase the finishing process of the finishing process. At the same time, the upper punch requires a reasonable transition of the thickness of the rod diameter to prevent stress concentration, which may cause the punch to break easily during extrusion. For the lower punch, in addition to the shape consistent with the hexagonal cavity of the combined concave mold, a certain margin must be processed, otherwise the gas in the cavity has nowhere to go, which will easily cause the product to collapse and the hexagonal edges are not full. In addition, the extrusion angle of the upper and lower dies must be reasonable, otherwise it is not conducive to the flow and forming of the metal.