A tube rolling process throughout which the so called "polygonisation" appears has been analyzed first experimentally and second numerically. Twelve stand stretch reducing mills were chosen and a series of experiments was carried out. Following those results, some laboratory tests were carried out using a draw bench. The results show that eccentricity appears when there is a change in the mean wall thickness. When "polygonisation" appears the middle part of the tube between the flange and groove sides becomes thickner than the other parts of the tube. The rigid-plastic finite element method was adopted, to analyze the process numerically. Some new techniques have been developed, e.g. a scheme for dealing with free surfaces and a method for dealing with three dimensional friction. After checking the validity of the computer programs, both two dimensional and three dimensional analyses have been carried out. It has been demonstrated that the two dimensional analysis is not entirely acceptable. As a result of the three dimensional analysis, some new information has been obtained, e.g. the three dimensional metal flow in the roll bite and the effect of friction on the eccentricity and on the front and back tensions. The final results indicate that eccentricity can be analyzed by the present computer program, therefore "polygonisation" can be analyzed and understood. The basic phenomenon of "polygonisation" has been understood to some extent.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:635867 |
| Date | January 1983 |
| Creators | Akiyama, M. |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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