Patent GB-819541-A (GB)
Title: Process and apparatus for the manufacture of hollow containers
IPC: B29C49/36
Filed: 1956-12-13
Abstract: 819,541. Moulding hollow containers. SUNTUBE CORPORATION. Dec. 13, 1956 [Dec. 20, 1955], No. 38067/57. Class 87(2). [Also in Groups XVII and XXXIV] A machine for making plastic bottles, &c. by blowing in moulds comprises a circular horizontal intermittently rotated table 15, Fig. 3, plan and Fig. 1, carrying on its upper surface twelve moulds each comprising two halve: 14, 14. The table rotates clockwise, Fig. 3, in 30-degree steps, each mould being stopped at stations A... L.  At station A whilst the table is stationary, the following operations (a) to (e) are per. formed :- (a) a plastic tube 102, Fig. 1 e.g. of polyethy. lene, is fed downwardly from an extruder into the space between two open mould halves, the lower part of the tube telescoping over the upper end of a blowing nozzle 103. There is one blowing nozzle for each muold. (b) The mould halves are closed to the Fig. 5 position. (c) A knife blade 173, Fig. 1, is advanced to sever the tube from the extrusion nozzle. (d) The blowing nozzle is lifted from the Fig. 1 position to the Fig. 5 position, whereby an enlarged portion 107 of the nozzle squeezes the material of the tube against the mould neck parts 64. (e) Knife blades 189, Fig. 5, cut off that part of the tube that depends below the mould. The table then indexes and the closed mould advances to station B, where air is admitted through nozzle 103 to blow the article as in Fig. 5. As the table progresses, blowing air is maintained in the article through stations B to J inclusive. At stations K, L and A the blowing air is shut off from the nozzles. At the same time as the operations (a) (d), and (e) are performed at A the reverse operations are performed at J, viz. the mould is opened, the blowing nozzle is lowered and the lower knives 189 are retracted. The finished containers may be ejected at J by a sudden application of high pressure air through the blowing nozzles. The table 15 is secured to a shaft 18, Fig. 2, rotated by electric motor 23 through a Geneva mechanism comprising a gear 22 on shaft 18 and an arm 31 on a vertical shaft 29. A series of switches 54 ... 59 is mounted stationarily near arm 31, and as the arm rotates it operates these switches sequentially. The mould halves are opened and closed by fluid pressure pistons 71 working in double-acting cylinders 72 connected by pipes 73, 74 to a head 76 supported on the underside of the table. Each mould has its own pistons 71 and head 76 and each head has valved sockets 77, 78. At station A, Fig. 1, is a fluid pressure head 79 which is fed with pressure fluid by pipes 93, 94 and is reciprocated by a piston 82 to engage nozzles 91, 92 thereon with sockets 77, 78, whereby the mould is closed. Piston 82 is controlled by a solenoid valve 87, actuated by switches 55 and 56. At station J, Fig. 2, is a similar arrangement to open the mould. The mould is cooled by fluid passing through inlet pipes 156, Fig. 2, outlet pipes 147, connection 159, pipe 161, pipe 164 in the shaft 18, hollow slip ring 171 and pipe 172. Each upper knife blade 173, Fig. 1, is carried by a frame 174 sliding in guides 178, the frame being reciprocated by the rod 179 of a piston 181 controlled by a solenoid valve 186 actuated by switch 57. Each blowing nozzle, Fig. 5, is supplied with air through pipe 131 and box 127, and is moved up and down by a double-acting piston 113 controlled by a solenoid valve 118 which is actuated by a microswitch 124 at station J to lower the nozzle and by switch 58, Fig. 1, (via contacts 122, 123) to raise the nozzle at station A. Blowing air is supplied to the nozzles from a pipe 132, Fig. 2, which feeds into a slot 143 on the periphery of a stationary column 138 about which rotates a block 134 fixed to the table 15. In the block are twelve orifices 136 which communicate at one end with slot 143 and at the other with nozzle feed pipes 132, 131. The slot does not extend around that part of the column that is opposite stations K, L, A so that no blowing air is supplied at those stations. Each pair of lower knives 189 is opened and closed by a piston (see Fig. 6, not shown) controlled by a solenoid valve actuated by a microswitch 124, Fig. 1, and by a switch 59 via contacts 209, 211. The drive from motor 23 to shaft 29 includes a shaft 32 having a pair of brake shoes 33 which are closed on shaft 32, at the end of a table-indexing operation, by a piston rod 43 controlled by a solenoid valve 47 actuated by switch 54. Alternatively, the rod 43 may be the core of a solenoid. In operation a switch 26 is closed to start a timer 24 which delays starting of motor 23 until a predetermined length of tubing 102 has been extruded. The motor then starts and rotates arm 31. The arm rotates to engage switch 55 which operates the two solenoid valves 87 at stations A and J to close the mould at A and open the mould at J. As the pressure head 79, Fig. 2, at station J moves, an arm 126 thereon actuates its microswitch 124 to lower the blowing nozzle and open the lower knives 189. (Alternatively, knives 189 may be opened at another station e.g. K, by a stationary cam which actuates the switches 124). The arm continues its rotation to actuate switch 56 to retract the fluid pressure heads at A and J out of engagement with sockets 77, 78. Then the arm operates switch 57 to cause the upper knife 173 to cut off the tube 102, switch 58 to raise the blowing nozzle at A, and switch 59 to close the lower knives 189 at A. Then the arm engages gear 22 to turn the table through 30 degrees, and finally engages switch 54 which actuates timer 24 to shut off the motor and apply brakes 33. After a dwell, during which more tubing 102 is extruded, the timer again starts the motor.