Patent GB-816160-A (GB)
Title: Improvements relating to the manufacture of flexible hose
IPC: B29D23/18
Filed: 1957-03-12
Abstract: 816,160. Extruding reinforced flexible hose. HOOVER Ltd. March 12, 1957 [March 29, 1956], No. 8120/57. Class 87(2). [Also in Group XXVIII] A method of making a flexible extensible hose consisting of a currugated tube. and a helical reinforcing coil comprises longitudinally extending the coil, extruding a tube about the coil and allowing or causing the tube to partially enter the convolutions between the coils and to partially set whilst the coil is so extended and then allowing the coil to contract longitudinally to cause the tube to form corrugations between the convolutions of the coil. The depth of corrugation of the tube may be different at different parts of the hose. In carrying out the method lengths of a close-coiled helically wound plastic covered wire coil 10 are placed on a reciprocating carriage 28, having an electrical heater 29 and, as the carriage moves the plastic covering is heated to fusion temperature, the carriage returned and the ends of the coil pressed together to " weld " the sheathing to form joints 33. The joined lengths of coil then pass to an air jet cooling station 34 and an advancing station 35 having advancing rollers 41, 42 belt conveyer 36 and pressure rollers 40. From the advancing station 35 the coil passes to a stretching station 45 comprising rollers 46, 47 rotating faster than the advancing rollers 41, 42 to extend the coil and to pass it to an extrusion head 21, having a vacuum chamber 55 and discharging into a pressure chamber 58, where a tube 13 is extruded over the coil at a slower rate than the passage of the coil through the head 21 so that stretching of the tube 13, aided by external pressure from the chamber 58 or internal suction from the chamber 55, causes the tube to contract diametrically and enter the convolutions between the extended coil. On leaving the chamber 58 the covered coil passes through water spray cooling means 61 to partially set the tube 13 and to pitchholding rollers 63, 64 rotating at the same speed as the rollers 46, 47 from whence it passes to a conveyer belt 65, travelling at the same speed as the coil and is kept extended by a pressure roller 69. After the roller 69 the coil contracts longitudinally forcing the tube to fully corrugate in the convolutions of the coil and, by natural cooling, to fully set and, finally, the hose is severed into separate lengths at the joins 33 by a cutting device 71, to form lengths of hose, e.g. for vacuum cleaners. For forming deeper corrugations at the ends of the hose, the vacuum chamber 55 or the pressure chamber 58 may be operated only at those positions. In an alternative arrangement, Fig. 2 (not shown), the pressure chamber is replaced by a booster fan which temporarily increases the vacuum where deeper corrugations are required. A preferred method of forming deeper corrugations, Fig. 3 (not shown), utilises a twospeed motor driving the rollers 63, 64 for increasing the rate of movement of the coil through the extruder, further extending the coils and thus, on their contraction, increasing the depth of corrugation. This preferred method, as opposed to increased suction or pressure, results in a tube of uniform thickness. The tube and the sheathing on the wire are preferably of the same material, e.g. polyvinylchloride, polyethylene or polymonochlorotrifluoroethylene. The machine may be made fully atomatic by, e.g. utilising the pressure roller 40 as a measuring device to count the coils of the helical wire and to operate switches to actuate the various operations.