The Design and set up of tooling for rotary draw bending

Typical Example:

  • 2.0″ O.D. x .065″ wall on 4″ center line
  • Wall factor 30 – 2 x “D” of bend

1. Bend Die

  • Hardened tool steel or alloy steel, heat treated and nitrided
  • Clamp insert is secured with cap screws and dowel pins
  • Drive key must be parallel to clamp insert
  • Bore should have a slip fit over centering ring or spindle

Note: Bend dies may have special tube grooves with captive lip or Empty Bending

2. Clamp Die

  • Hardened tool steel or alloy steel, heat treated and nitrided
  • Preferable length is 3 X tube O.D.
  • Tube groove is grit blasted or may be serrated if less than preferred length
  • With tube held in bend die, advance clamp die and adjust for vertical alignment
  • Adjust for parallel contact with entire length of clamp
  • Adjust for pressure

3. Pressure Die

  • Alloy steel and nitrided
  • Tube groove must be parallel to back of die
  • If follower type pressure die is used, length equals 180 degrees + 2 O.D.
  • If a boosted system is used, groove should be grit blasted
  • With tube clamped to bend die, advance pressure die and adjust for vertical alignment
  • Start with minimal pressure and increase as required in small increments

4. Mandrel

  • Type of mandrel and number of balls indicated by Tooling Selection Guide
  • Aluminum/Bronze, chrome, or Kro-Lon mandrels for ferrous tubing. Only chrome mandrels for non-ferrous
  • Gain best results with most mandrels when shank projects a small amount past tangent (bend and try)
  • Lube I.D. of each tube

5. Wiper Die

  • The Tooling Selection Guide indicates when a wiper may be required
  • Push tube over properly located mandrel and bring clamp and pressure dies up to bending position
  • Slide wiper along tube as far as possible into bend die then secure to holder
  • Unclamp pressure and clamp dies, tip of wiper should be “very close” to tangent
  • Adjust for rake and vertical alignment
  • Lube each tube and the wiper

No Matter What You want to Bend Or Why you want to Bend It

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