Image Number 3 for United States Patent #4543811.
A progressive forming method of a product having a varied cross-sectional length in the direction of supply of strip material. A material is first drawn so that a portion which corresponds to the portion of the product having a cross-sectional length larger than the smallest cross-sectional length is processed. The material is elongated by an amount corresponding to the difference of the length from the smallest length. Operations that require no differential elongation in the direction of supply are all performed subsequently, since such operations do not require excess stock that must ultimately be scrapped.