| 摘要 |
1,231,445. Pipe-laying apparatus. IMPERIAL CHEMICAL INDUSTRIES Ltd. 19 Nov., 1969 [3 Dec., 1968], No. 57273/68. Heading F2P. A method of laying a land drainage tube comprises transporting a flat foil over the land, feeding the foil to a crimping device wherein at least one edge of the foil is crimped, twisting the crimped foil into an overlapping spiral tube and deposting the tube upon the land, the foil being crimped, twisted and deposited at a rate proportional to the rate of transport over the land. The crimping results in small gaps at intervals between the overlapping edges of the foil, through which water can drain from the soil. In a preferred embodiment a tractor drives a mole plough 4 through ground 5 to form a trench in which the drainage tube is laid. Framework 1, 2 and 3, is attached to the tractor and supports a rotatable cage comprising side members 8, a top plate 9 journalled in bearing 6, and a combined pulley and bush 11 journalled in bearing 7. Mounted between side members 8 is a spool 12 carrying foil 13, a pair of guide rollers 14 and a pair of crimping rollers 15, embossed to provide a herringbone or other crimp pattern to the foil, and driven by cog 16 which engages circular toothed track 17. Thus as the cage is rotated by a belt drive from pulley 18, which is driven by the land wheels of the tractor, to pulley 11, cog 16 and hence crimping rollers 15 are rotated. The rotation of rollers 15 and the forward movement of the tractor causes foil to be pulled off spool 12, crimped between rollers 15, and helically wound by the rotation of the cage into an overlapping tube which passes into the trench formed by mole plough 4. The drive ratio between the tractor and the cage may be varied in order to control the extent of the overlap of the foil. The foil is preferably of plastics, such as rigid polyvinyl chloride, A.B.S. (acrylonitrile-butadiene-styrene) resins, polypropylene or polystyrene, but other materials, e.g. metal, may be used. Preferred crimping patterns are illustrated in Figs. 5-7 (not shown). |
