| 摘要 |
1312350 Making pipes by winding on mandrels AMALGA CORP 9 July 1970 [9 July 1969] 33295/70 Heading B8G [Also in Division F2] A mandrel having an unthreaded central portion 9 and at least one end 7 helically knurled as at 6 is coated with a release agent and then helically wound with resin-impregnated glass filaments at a winding pitch greater than the pitch of the helical knurls. The resin impregnated filaments are then cured and at least part of the mandrel is removed to leave the windings in the form of a pipe. As shown the mandrel comprises one end 7 that is helically knurled as at 6 and a smaller end 10 that is helically knurled as at 5, the diameters of the two ends being such that the finished pipes can be screwed one into another. The smaller end 10 may comprise an externally knurled ring 11 that is not coated with a release agent in order that it may remain within the pipe on a reinforcing member. |
