Our website uses cookies. By using the website you agree ot its use. More information can be found in our privacy policy.

LS-DYNA used to analyze the drawing of precision tubes

Long precision tubes are commonly made using the floating plug tube drawing process. The process has been analyzed using various methods e.g. upper bound method and FEM [1-10]. The die land and the plug land are usually cylindrical and form a cylindrical bearing channel between the die land and the plug land. The influence from the length of the bearing channel on the drawing force has only been dealt with in very few papers. In [2] it is recommended to use the shortest possible bearing channel in order to reduce the drawing force. A short bearing channel is also recommended in [6] both in order to reduce the drawing force, but also in order to increase the stability of the drawing process. The authors have not found any papers dealing with which influence the shape of the bearing channel has. The paper describes an analysis of tube drawing with a floating plug carried out using LS-DYNA®. The analysis shows that the drawing force, with conventional tooling, is heavily influenced both by the length and the shape of the bearing channel. The analysis has given inspiration to a new plug design, where the cylindrical plug land is replaced with a circular profiled plug land. Simulations of tube drawing with the new plug design show that the drawing force can be decreased and that the drawing force is nearly independent of the length of the die land and of small variations in the die land angle. With a conventional plug it is necessary at start up to make a dent in the tube behind the plug in order to force the plug into the right position in relation to the die. Without a dent the plug will be pushed ahead of the die and no reduction of the tube wall thickness will take place between the plug land and the die land. The dent is commonly made manually with a hammer and making the dent is difficult. If the dent is not made big enough the plug may pass the dent without being brought in the right position in relation to the die and if the dent is made too large this may lead to tube fracture. To ease the threading process at start up it is suggested to make the plug with a conical front end. By doing so the plug becomes self-catching; that is the frictional forces between the conical front end and the inside tube wall will set the plug in the right position in relation to the die during start up. Simulations show that the “self-catching plug” principle works.

application/pdf A-II-02.pdf — 2.6 MB