Like squaring the circle – the Wieland Logform calculator
A clever idea made higher mathematics applicable for everyday use
Until 1966, traditional calculation methods were used for cold work. Science had moved on, though, and now uses a much more exact, but also more complex method named "logarithmic form changes". Wieland therefore developed a slide rule that made theory manageable in everyday working life.
"In the field of forming technology, it is generally not possible to produce an excellent product both economically and qualitatively without obtaining a comprehensive case to case picture of the values of the deformation, the force and power required, the material condition, etc.". These are the first lines of the preface to the 34-page manual of the Wieland Logform calculator from 1967. This innovative slide rule enables the proverbial squaring of the circle in two ways: maximum manufacturing quality at the lowest possible cost – and the fast and simple application of complicated logarithmic processes by master craftsmen and by foremen "without previous mathematical knowledge".
For non-technicians: The deformation parameter can be used to determine geometric changes in a workpiece during forming and, for example, to precisely calculate forming forces. When and by whom the Wieland Logform calculator was developed is not known. In any case, in December 1964, Wieland's patent department received a letter describing a "slide rule for calculating with logarithmic form changes" and suggesting that the registration of industrial property rights for the innovation be examined.
In the spring of 1965, Wieland contacted several relevant manufacturers with the subject "Special slide rule for non-cutting form changes" and asked for an offer for 200 and 500 pieces. The IWA-Rechenschieberfabrik in Esslingen was awarded the contract, the prize unfortunately not being documented. It must have been considerable, because in November 1966, 32 employees in Vöhringen had to sign for the receipt of the loan item "only for use within our company".
Despite the considerable level of innovation, it was not possible to register the Logform calculator as a trademark. Reason: The designation is legally a pure "quality specification". An employee of the patent department therefore stated tersely already in November 1965: "Unless the examiner is asleep, the patent office will refuse the registration.
This did not detract from the high practical use of the "Wieland Logform Calculator" in everyday production. It made a valuable contribution to the quality of Wieland’s semi-finished products until the introduction of digitalisation.
The white page is used to calculate general values such as cross-sectional area and weight-per-meter. Logarithmic form changes can be calculated on the green side.
Innovation in 1965: A Wieland employee records ideas, calculations and sketches of the Logform Calculator on notepaper and calendar sheets.
