Abstract
The hydrostatic extrusion of the billet is a new extrusion process differing from the conventional method in utilizing the pressurized liquid and keeping the material in contact with the dies. The practical use of this process involves a serious question concerning how to prevent the stick-slip motion. There are, it is considered, various factors that bring about the stick-slip motion, such as lubricants, extrusion ratios, the materials of the billet and die angles. In the present study the stick-slip motion has been analyzed in terms of these factors using an electromagnetic oscillograph. The results obtained are as follows.
(I) The temperature of oil film of lubricant formed inside the dies holding the billet plays an important part in causing the stick-slip motion.
(2) The smaller die angle will render the lubricant to be preventive of the stick-slip motion.
(3) Large stick-slip motion has always appeared with bulging deformation at the extrusion of brittle materials.
