| 摘要 |
A variable-rigidity extrusion (A) is produced by a continuous extrusion process consisting of the provision of an extrusion head (1) with first, second and third successive extrusion dies (3, 4, 5) and of the continuous supply to these extrusion dies of respective flows of elastomeric materials, of which that directed to the first extrusion die is harder than that directed to the second die. Passage through the first and second extrusion dies is permitted and inhibited alternately for predetermined time intervals and the flow of elastomeric material directed to the alternately inhibited extrusion die is recycled. |
