| 摘要 |
<p>The material to be extruded is gripped by friction by a driving surface, forming in conjunction with a non-driving surface a passage, the area of the driving surface in contact with the material being greater than that of th enon-driving surface and extending over a sufficient length to allow the extrusion pressure to be transmitted by friction. The section of the passage varies in the lengthwise direction as the material moves forward, initially fitting round it without appreciable deformation. It is in close frictional contact, by the driving surface, with the material and merges into a different shape so as to deform the latter. The variation of the passage can be smooth or in steps.</p> |
