Tube-bend tooling: square-back wiper dies or wiper inserts?

摘要

Wiper dies are a fundamental requirement, in modern tube bending applications in which tubes are bent at increasingly tight bend radii with increasingly thinner wall thicknesses. The design of the wiper die plays a key role in its performance and durability, as does its manufacturing method and the material from which it has been constructed. As the D ratio (the centerline bend radius divided by the tube diameter) decreases and the wall factor (tube diameter divided by the wall thickness) increases, the tube is less resistant to bending. As a result, it has a greater tendency to collapse rather than follow the form of the bend. Consequently, the material must be contained physically-surrounded at all points, internally and externally- where the bend takes place, to prevent tube collapse and any resulting deformities, such as wrinkles. This is needed in the tangent area, predominantly where the tube changes from a straight to' a bent section and also where the material flows ahead and behind of the tangent point.