| 摘要 |
PCT No. PCT/GB91/00350 Sec. 371 Date Sep. 17, 1992 Sec. 102(e) Date Sep. 17, 1992 PCT Filed Mar. 6, 1991 PCT Pub. No. WO91/13559 PCT Pub. Date Sep. 19, 1991.The manufacture of flexible tubes of two or more layers of a material such as felt which can absorb synthetic resin comprises feeding a first web in the direction of its length and folding the web so that its edges came face-to-face and are sewn together by stitches which loop round said edges, the second layer being wrapped around the first and its edges sewn in a similar manner, the looped stitching being such that when the tube is inflated to circular form the extremities of the edges in the stitching loops in each layer come into butting contact, whereby there are no regions where the layer has a double thickness of material. |
