| 摘要 |
<p>1534610 Producing branched pipes W A CLARK 1 Sept 1976 [18 Nov 1975] 36174/76 Heading B5A A branched tube 2 (Y, T or inspection junction) is produced by placing a slug of plastic material (clay, concrete or thermoplastics) in a split mould 1 defining the outer shape of the tube, introducing opposing plungers 10/11 into the slug to shape the main cavity 3 and force excess material into a branch piece 6, and then introducing a hollow plunger 30 to shape the branch cavity 33. The split mould is hinged and held together by toggle clamps (see Figs. 7/8, not reproduced). Each plunger 10/11 comprises metal discs 12/14 sandwiching an oiled felt disc 13. As each plunger moves against the plastic material, the felt expands radially so that the bodies of the plungers do not contact the material, while air escapes through the felt. The plunger 10 is preferably placed in a position 61 while plunger 11 moves to a position 62, where it is then met by plunger 10. Overshooting of position 62 is effected. Before or after withdrawal of plungers 10/11, plunger 30 cuts a core of material using an oversize knife edge 36, the core passing through the plunger hollow 42 with little friction (as it is undersized by edge 36) into a cage 43, where it expels any core present from a previous moulding.</p> |
