| 摘要 |
The tube forming the rollers is helically wound from extruded plastic material onto a mandrel, and while it is still soft a strip of surfacing material is welded to it tangentially to the angle of the helix the width being adjusted to form spirals which are joined together the profile being then drawn and cut into lengths to form the rollers. The extruded roller is cheaper than a thermoplastic roller, and welding of the surfacing material in a single stage further reduces cost. |
