| 摘要 |
1,094,819. Molding clay pipes. PACIFIC CLAY PRODUCTS. July 7, 1965 [May 6, 1965], No. 28861/65. Addition to 977,373. Heading B5A. In a method of moulding a clay pipe between a central mandrel and a surrounding elastomeric sleeve as described in Specification 977,373, a void is left at the top of the moulding cavity so that upon release of the moulding pressure the pipe may expand in an axial direction, which expansion dissipates deleterious stresses. In an embodiment, not shown in the parent case, the compression chamber is formed between a mandrell 20, fixed, by means of an upper pipe 119, to a mounting 123 carried by fixed mould block 130, and a hydrostatically actuated resilient sleeve 122 carried within said mould block. Slidable within the pipe 119 is a feed tube 139 carrying a hopper 145, which tube is joined by bolts 141 passing through slots in pipe 119, to a sleeve valve 131 which is therefore slidable within block 130. The lower end of the compression chamber is closed by a vertically reciprocable member 142. In operation, valve 131 is raised to clear ducts 159 in the upper end of mandrel 120 thus allowing material to be fed from hopper 145 to the compression chamber. Air is then exhausted, to facilitate packing; through channel 161 in the valve and channel 163 in the block 130, and the pipe moulded by sleeve 122. The pressure is then released, the pipe allowed to expand radially and axially, and then withdrawn by lowering member 142.
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