NOTE: This does not apply to high strength mild steel, ultra high strength steel and aluminum panels.
Rule: Straightening panels by heat treatment reduces the amount of excess material to a greater extent than initial stretching.
Various heat treatment methods
NOTE: Depending on the amount of excess material, different heat treatment methods are used.
Editing with a torch.
- If excess material is observed in a significant area, a welding torch is used (burner size 0.5 - 1.0 mm). Use a weak flame.
- The surface of the metal is briefly heated in patches and then immediately cooled with a damp sponge.
- Requirement: Ability to properly handle the welding torch and knowledge of steel annealing colors.
- Advantage: No damage to the metal surface.
Stretching with a hammer torch and a dummy die.
NOTE: Dressing efficiency is increased by faster heating and cooling.
If the excess material is concentrated, then the dressing efficiency can be increased by carefully using an aluminum or wooden mallet after heating.
Requirement: Ability to recognize the stress state of the material by observing the surface to be dressed.
Styling with a carbon electrode.
- If the panel areas are only accessible from one side, or if the panel is only slightly buckled, carbon straightening is the preferred straightening method.
- Requirement: Bare metal surface.
- Disadvantage: The presence of scratches and hardening of the surface.
Editing with a copper electrode.
Small, sharp dents that are facing outwards can be repaired using a copper electrode.
Sharpening with a torch and body files.
NOTE: When used correctly, this method can be used without removing all attachments (roof sheathing, wiring harnesses, etc.).
Small dents (with only slight stretch): When processing the edges of the dent in a spiral inward direction, the dent is heated with an oxy-acetylene torch (burner size 1 - 2 mm, excess gas flame) up to a temperature of approximately 250°C.
Fast work with a body file removes heat from the boundary zone and so on until the dent is straightened. It is preferable to alternate work with two files. This increases the amount of heat that can be removed.
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