Wyniki 1-1 spośród 1 dla zapytania: authorDesc:"HELENA JOHANSSON"

Temperatures at wire–drawing; simulations and verification efforts

  1. Introduction. The wire drawing process may seem to be simple, but there are crucial issues as lubrication between die and wire. Failure in lubrication will give serious surface flaws. The lubricant properties are influenced by temperature and sheer rate. An increased temperature will decrease the viscosity of the lubricant. It is reasonable to assume that the temperature at the die entrance will be one of the parameters which determine the amount of lubricant between die and wire. A drawing machine is fed by electrical energy, which is transformed to mechanical energy. In the die this mechanical power is used to reduce the wire area. A small fraction of the energy is stored in the wire as dislocation, but most of the energy will dissipate to heat. The heat may be divided into friction heat and plastic deformation heat. Thus the highest temperature will occur in the end of the reduction zone in the die. At too high temperatures the lubrication may cease. This temperature is thus very important, but hard to measure. Siebel [1] has analyzed the wire drawing process, and given an analytical equation for drawing force. In Siebels‘ equation friction force is taken as a fraction of flow stress. Siebel and Kobitzsch [2] presented an analytical solution of the temperature in the contact zone. The wire was assumed to absorb 80 % of the friction heat. Nilsson [3] tried to use the wire and the die as a thermocouple. His study indicated a temperature of about 500°C [...]

 Strona 1