Method and apparatus for regulating the length of workpieces

A method of regulating divisional spacings of a running metal spring band of indefinite length during a hardening treatment thereof;

• subsequent steps of heating said band to a red-hot state and quenching said band;
• said band having alternating cuts on opposite longitudinal edges, comprising the following steps:
• (a) feeding said band parallel to the length thereof by passing said band between two conveying roller pairs spaced from one another in a travelling direction of said band;
• (b) heating the running band to a red-hot state at a first location;
• the heating step forming part of said hardening treatment;
• (c) quenching said band at a second location situated downstream of said first location as viewed in a running direction of the band;
• the quenching step forming part of said hardening treatment;
• (d) scanning said cuts simultaneously at consecutive third and fourth longitudinally spaced locations being at a desired divisional spacing from one another and being situated between said two conveying roller pairs upstream of said second location;
• (e) generating first signals in response to each cut passing through said third location and second signals in response to each cut passing through said fourth location;
• (f) forming a third signal by comparison of said first and second signals;
• said third signal representing a deviation between the desired divisional spacing and the actual distance between cuts;
• and
• (g) regulating, between said roller pairs, the actual distance as a function of said third signal during a red-hot state of said band.