The Cause of offset of Rerolled Bars in Cold Re-drawing Area
In the process of cold re-drawing operations of steel bars, problems such as deviation from the normal shape of the steel bar, offset of the steel bar, deviation from the drawing size specification, unstable surface quality, serious steel bar fracture and poor straightness of the steel bar often occur. The reason for the offset of the rerolled bar mainly includes the die bite angle, the tensile pressure of the feeding roller, the pulling plate and the surface roughness of the cold drawing die. The following will explain in detail the causes of the offset of the rerolled bar in the cold re-drawing area.
Die bite angle is the downward angle of the edge of the die relative to the plane of the steel bar. This angle will affect the deformation amount of the entire cold drawing process in the coming process, and it will also affect the offset of the steel bar. Generally speaking, if the angle increases, the deformability of the steel bar increases, and the offset of the steel bar increases.
The tensile pressure of the feeding roller will also affect the offset of the steel bar: when the feeding rollers has a larger speed difference, the pressure of the feeding rollers will also increase. If this pressure is too large, the steel bar will be forced to the die and become serious, resulting in an abnormally large offset of the steel bar and material scraps.
The roughness of the surface of the cold drawing die will also have an impact on the offset of the steel bar. Generally speaking, if the surface roughness of the die is too large and the surface of the steel bar is not smooth, the friction between them increases, and the offset of the steel bar is large, which causes the steel bar to be scraped out by the die.
The last factor is the pulling plate. This part is also a factor of deformation and offset of the steel bar in the cold re-drawing process. Pulling plate refers to a device which can usually maintain constant drawing speed or variable drawing speed according to requirements. In the process of steel re-drawing, when the pull plate moves up and down, the speed will accelerate, and the coefficient of friction between the steel and die will change accordingly, thus causing steel offset.
In summary, the causes of deviation from the normal shape of the steel bar, offset of the steel bar and deviation from the drawing size specification in the cold re-drawing area can be attributed to the bite angle, tensile pressure of the feeding rollers, surface roughness of the cold drawing die and pull plate. Therefore, these factors should be considered when performing cold re-drawing operations and moves should be taken accordingly to reduce the offset of the steel bar.
