Materials are selected to suit the specified product requirements at the possible lowest price. However, the mechanical properties, surface, deviation from thickness, width, straightness, and flatness of the raw material influence roll forming machine design.
Mechanical Properties
During roll forming process, the strain (elongation) of the outside fiber of the strip must remain below the uniform engineering strain. Therefore, the forming machine designer must know the yield strength, maximum tensile strength, and elongation of the material. These data are usually available from the material supplier.
In low carbon steel, the correlation between hardness and tensile strength is reasonably good. Therefore, hardness is sometimes used to check the material soft or hard. However, good hardness material does not guaranty good formability. Cold work such as roll forming, tensioning, compressing, and other operations. Which will increase the yield and tensile strengths and reduce elongation.
Based on past experience, the roll forming machine designer can usually judge the anticipated formability of the material, including the minimum radius and springback. And materials having high yield strength, small difference between tensile and yield stresses, and small elongation require more forming passes.
Springback Of Material Influence Roll Forming Machine Design
The method of roll forming and elastic modulus of the material will influence the mechanical properties of the material, springback.
Tolerance of Material Influence Roll Forming Machine Design
Thickness
The material must be able to pass through the gap between the rolls without thickness reduction. Therefore, roll gap is calculated as the sum of the maximum specified thickness plus maximum thickness tolerance plus maximum coating thickness plus the maximum depth of embossing.
Attempting to roll forming thicker material than the specified maximum thickness could break the rollers, damage the equipment, reduce the quality of the product. And additionally create waviness, scratches, or other problems. The thickness also affects the strip width. The width and dimensions are calculated for the mean thickness. If the thickness is at the maximum plus tolerance, then some dimensions will be smaller. And If the thickness is at the minus tolerance, then some dimensions will be larger.
Width
Width tolerance will obviously influence some dimensions of the product. In most cases, the strip width tolerance will add to the roll forming tolerance at the outside lip. If this dimension is critical and is tightly controlled, then the extra material may gather at the center, creating waviness and other problems.
Believe Industry Company have an experienced team to design the machines. And the designs catch up to the latest technology in the world.
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