When bending tubular parts, the quality of the finished product depends not only on the determination of specific process parameters but also—and crucially—on the design of the bending machine tooling and the selection of its parameters.
How are the key parameters for bending machine tooling determined? Common bending methods include rotary draw bending (wrap bending), roll bending, press bending, push bending, and stretch bending. At Huameng Machinery, we primarily utilize the rotary draw bending method. For this method, the minimum bending radius R (measured at the tube centerline) is generally considered to be 1.5 times the tube's outer diameter (d). However, extensive practical experience has shown that when the wall-thickness-to-diameter ratio (t/d) is 0.12 or greater, the minimum bending radius can be reduced to R = d.
Common issues encountered during tube bending include rupture of the outer tube wall, wrinkling of the inner wall, and excessive cross-sectional ovality. To address these problems, we have implemented specific improvements to the bending die groove and the guide plate, which have proven highly effective in practice.
Method 1: Design the bending die groove so that its periphery extends outward by a certain amount—typically 0.45 times the wall thickness (t)—and maintain a clearance of 0.4–1 mm between the bending die and the guide plate. This effectively controls and mitigates cross-sectional deformation during the bending process.
Method 2: Design the guide plate groove as a composite arc profile—specifically, incorporating a counter-deformation groove to offset the ovality and cross-sectional distortion that occur during bending—and maintain a clearance of 1.5–2 mm between the bending die and the guide plate.
The above points summarize the experience Huameng Machinery has accumulated regarding bending machine tooling design during the processing of various tubular materials. We adhere strictly to the business philosophy of "Customer First, Integrity-Based Operations" and sincerely welcome both new and existing clients; our entire team is dedicated to providing you with comprehensive service.
