Patent GB-760537-A (GB)
Title: Improvements in or relating to pipe forming machines
Inventor: BOGGS HERBERT D
IPC: B28B21/30
Filed: 1954-08-09
Abstract: 760,537. Centrifugal moulding of plastic pipes. FIBERCAST CORPORATION. Aug. 9, 1954, No. 23144/54. Class 87(2). Apparatus for centrifugally moulding reinforced plastic pipes comprises a mould support and drive unit, a mould conveyer unit, a mould holding down unit, polymerization means and plastic material distribution means. Mould support and drive unit, Figs. 2, 3, 14. Journalled in bearings 20 supported by the end and cross members of a frame 12 are axles, e.g. 22, on which are fixed rollers 30 having metal shoes 32. The axles are driven, through belts 54, 66, 70, 82 by a motor 36. Base plates and single members, e.g. 90, 94 are slotted for adjustment of the bearings and pulleys. Mould conveyer unit, Figs. 3, 4, 7. Chains 116, having spaced rollers 122, run along ramps 102 and are driven by a motor 136 through a speed reducer 134 and chain 128 to pick up moulds 34 from a rack 98 and deliver them to a rack 100. The ramps are supported through pivotal connections by pistons 112 of hydraulic cylinders 114. An alternative form of mould conveyer unit is shown in Fig. 4, comprising a chains 152 with mould positioning lugs 154 fastened thereon, these chains similarly running over ramps. Mould holding down unit, Figs. 2, 3, 4. Rollers 162 having shoes 164 are journalled on axles mounted in a frame 156, 160. The frame is raised and lowered by cables 182 fastened at one end to the frame and at the other end to counterweights 184 and passing round pulleys 178, 180 at the four corners of the structure. The shafts on which the pulleys are fixed are driven by belts 196 from gear boxes 194, one at each end of the structure, and the drive to these gear boxes is taken from a motor 186 through a shaft 192. The pulleys 180 are then driven at the same speed and the frame kept horizontal as it is raised and lowered, its weight in its lowered position holding the moulds down. Polymerization means, Fig. 2. A series of gas burners 204 fed by supply pipes 205 and flexible pipes 205a is arranged so that the burners fit between the rollers 30 and allow the heat of the flames to reach the mould. Plastic material distribution means, Figs. 2, 10, 11. A shaft 286 from a motor 288 drives, through bevel gears 284, 285 the driving means for the sprocket of a drive chain 272, Fig. 11, which accomplishes the movement of a wheeled carriage 210, Fig. 10, which runs on tracks 206, 207. On the carriage are mounted pumps 246 which force a plastic-forming solution through tubes 208, also mounted on the carriage and projecting from it for a distance such that they reach about halfway into the moulds when the carriage is moved up to them. Suitable plastic-forming substances are polyfunctional acrylic resins diallyl dicarboxylic acid and maleic acid esters. The pumps are driven by a shaft 248 from a gear-reduction-box and drive-motor-unit 260 and draw solution from a container, not shown, through a flexible pipe 267 and supply connection 266 and force it through flexible unions 270 to the tubes 208 at the ends of which are fitted spray heads 216. The arrangement is duplicated on the opposite side of the structure. Mould, Fig. 8. The mould consists of a tubular section 298 provided with end flanges 300 and flanged guide wheels 302 in its length. End caps 306 held in place with set screws and suitably sealed keep the plastic-forming solution in the mould. Operation. Reinforcing filaments are first inserted in the mould, one way being to roll a fabric mat into tubular form, slip it into the mould and push it against the inside of the mould by a guide member or by air pressure. Unwoven fabric may be inserted by similar means, or fibres can be blown into the mould. Glass fibres are preferred, but nylon, rayon, cotton, wire and other materials may be used. The moulds, prepared with the reinforcing material, are fed to the apparatus on the rack 98 and the motor 186 operated to raise the frame 156, 160 and the rollers 162. The hydraulic means 114, 112 are then operated to raise the ramps 102 and bring the mould conveyer chains 116 level with the rack 98, from which the moulds drop on it when the motor 136 is started. The chains 116 move the moulds into the machine above the rollers 30 and the hydraulic means are operated to lower the ramps again, allowing the moulds to drop into position between pairs of rollers. The motor 186 is then operated to lower the rollers 162 until their weight and that of the frame 156, 160 bears on the moulds. The motor 186 is then stopped and the motor 36 started to drive the rollers 30 which cause the moulds to spin. The wheeled carriages 210 are then advanced by operation of the motor 288 till the spray heads 216 meet in the middles of the moulds, and the motor unit 260 is started to drive the pumps 246 and cause plastic-forming solution to be sprayed on the fibre reinforcement. The gas burners are turned on to heat the moulds and, with the moulds still spinning, the carriages 210 are gradually withdrawn, causing the material to penetrate the whole fibre layer by centrifugal action and form a resinous binder. More than one pass of the spraying unit may be given if necessary. The spinning and heating are continued for some time after the spraying to polymerize the material and form the pipe. The rollers 162 are then raised, the ramps 102 raised to bring the moulds level with the delivery rack 100 and the chains 116 operated to roll the moulds out on it.