| 摘要 |
1293766 Coating tubes by extrusion BENTELER-WERKE AG 26 Nov 1969 [16 Dec 1968] 57804/69 Heading B5A [Also in Division F2] A metal tube 1, Fig. 1, is sheathed with expanded plastics, e.g. polyolefine expanded by 0À2 to 1À5 parts by weight of azodicarbamide, on passage through a crosshead extrusion die 4 located in a vertically descending path of the tube 1 which is helical and substantially of the same diameter as the tube coils 30, 30a of vertically spaced coaxial reels 2, 2a from which it is respectively drawn and fed to. The crosshead 4, Fig. 2, which is fed with plastics from a passage 22, includes a mandrel 19 which is axially adjustable in a nut 38 to vary the dimensions of the extrusion orifice 37 and contains a bore 18 of more than twice the diameter than the tube 1 which is guided therethrough along the curvature of its helical path by orifices 40, 41 of replaceable members 20, 39, the member 20 being clamped between parts 19a, 19b of the mandrel 19. The axes of the orifices 40, 41 are preferably tangential to the path of the tube 1 as in the Fig. 2 embodiment wherein the tube 1 passes through the orifice 37 at an angle to the axis thereof, but in the Fig. 3 embodiment (not shown), the orifices (40, 41) are arranged for the passage through the orifice 37 to be coaxial therewith. The bore 18 is connected at 15 to vacuum, which may extend to the orifice 37 via passages through the member 39. The tube 1 is fed to and drawn from the head 4 by means 3 and 3a. The extruded sheathing is smoothed by a device, Fig. 4, which comprises a plurality of upper and lower radially adjusted laminar blades 44, 43 provided with rounded smoothing edges, within a casing 31 into which controlled temperature fluid is admitted to function as a lubricant and as a fluid bearing for the pipe, the initial blades 44, 43 being sprayed with liquid from a ring nozzle 45. The tube is then cooled in two stages 11, 12, the latter using coolant of lower temperature and intermediate which is located a fluid bearing 33, Fig. 6, wherein the sheathed pipe is supported between opposed fluid jets which may be assisted by a ring nozzle 46 at the entry thereto. The cooled sheathed tube is thereafter supported on rollers 32 and passes through a device 35, 36 which detects a connector (1a), Fig. 8 (not shown), between consecutive coils and, after a delay, actuates a saw 34 which travels with the coated tube to cut through the connector.
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