| 摘要 |
A METHOD OF EXPANDING A TUBE OF PLASTICS MATERIAL IS DISCLOSED IN WHICH A LONGITUDINALLY TRAVELLING TUBE 10 IS PROGRESSIVELY DIAMETRICALLY EXPANDED BY INTERNAL FLUID PRESSURE IN AN EXPANSION ZONE 20 BETWEEN AN UPSTREAM PLUG 24 AND AN EXPANDABLE DOWNSTREAM PLUG 26. EXPANSION OF THE TUBE IS CONTROLLED IN RESPONSE TO PARAMETERS WHICH DIRECTLY OR INDIRECTLY INDICATE VARIATION IN THE RELATIVE VELOCITY AT WHICH MATERIAL IS DELIVERED TO AND REMOVED FROM THE EXPANSION ZONE, SUCH AS DETECTING UPSTREAM TUBE VELOCITY 38, EARLY EXPANSION DIAMETER 36, AXIAL FORCE 39 ON A SIZING DEVICE 28 OR THE TUBE DIAMETER 41 JUST BEFORE THE EXPANSION ZONE. FGURE 1 |
