Patent GB-949361-A (GB)
Title: Improvements in or relating to injection moulding machines
IPC: B29C45/06
Filed: 1958-12-27
Abstract: 949,361. Injection moulding machines. BRITISH UNITED SHOE MACHINERY CO. Ltd., and G. C. BARTON. March 24, 1960 [Dec. 27, 1958], No. 41794/58. Heading B5A. An injection moulding machine includes a turret assembly comprising a plurality of mould assemblies 14 mounted on a table 34 which is rotatable about a vertical axis, indexing mechanisms M to move each mould assembly in turn into and out of an injection station I, and a presenting device R for moving each mould assembly at the injection station relatively to the table to present it to an injection nozzle 12. Locating means are provided for determining the injection position independently of the precise position of the table. The presenting device moves the mould assembly from a position in which its weight is supported by the table to the injection position in which its weight is not so supported. The invention is described as applied to the moulding of bottom units on to lasted shoe uppers, the bottom units being formed of P.V.C. polymer or copolymer resin. General arrangement. (Fig. 2). At a loading station L a first operator positions a lasted upper on a foot form 24 and adhesive is applied. At two drying stations D infra-red heaters 18 secured to a guard rail 16 dry the adhesive. At a mould closing station C a second operator moves the foot form 24 up into its closed position and fluid-operated mechanism CM closes side mould members 20 (Fig. 4). The mould assembly is then moved to the injection station I where it is rocked and then moved radially towards the injection mechanism IM. After injection the mould assembly is indexed through five cooling stations to an opening station O where the side mould members 20 are opened. A vibratory dispenser V delivers plastic material from a hopper H to an injection cylinder 10. The table 34 is ring-shaped and supported on rollers (Fig. 8, not shown). Each mould assembly is rockably supported by a pin 76 (Fig. 5), in brackets 74 secured to the table 34. Except in the injection position the mould assembly is held in a rest position by engagement of a roll 80 (Fig. 5), with a guide rail 82. Mould assembly construction.-The mould is formed by the foot form 24, a sole member 22 (Fig. 5), and the side members 20 (Fig. 4). The side members 20 are secured in channel-shaped carriers 110 and are each opened and closed by toggle arrangements 114, 118 and 126, 130 connected by a link 124. Toggle-actuating arms 136 are connected by pivoted links 138 to an operating member 144 pivoted at 146. At the closing station C a plunger 148 is moved upwardly to pivot the member 144 while at the opening station O a plunger 150 pivots the member 144 in the opposite direction. The foot form 24 (which includes a displaceable heel portion 25) is adjustably mounted on side plates 160 pivoted at 164 on an arm 162 pivoted at 76. Downward swinging of the arm 162 is limited by a pin 181 engaging in a slotted portion 179 of a brace 176. The foot form can be locked in operative position by a latching member 197 having a handle 200 and pivoted at 196. After raising handle 200 the latching mechanism can be released by means of pushrods 226 operated by rotating handles 190 clockwise. The mould assembly comprises a cut-off device similar to that in Specification 917,522 and comprising a sliding gate 280 (Fig. 4), having an injection aperture 282. When the mould has been filled the pressure of the plastic material causes a spring-loaded plunger 310 (Fig. 5), in the sole member 22 to actuate a microswitch to effect movement of the gate 280 and also to stop the injection screw. Sprue removal from the gate 280 is effected by a lever 324 (Fig. 4), pivoted at 326 (Fig. 5), and operated through linkage 328, 330, 332, 334 when a roll 340 engages a cam 341 (Fig. 2). Mould assembly presenting device R and locating device.-The presenting device R comprises a thrust member 264 (Fig. 2), operated through toggle linkage by an hydraulic cylinder 256. The thrust member 264 engages the mould assembly 14 and swings it rearwardly about the pin 76 to engage the mould inlet 230 with the injection nozzle 12. A locating member 276 (Figs. 4, 5), seats in a socket 278 fixed to the machine frame so that the mould assembly swings about the socket 278, the pin 76 being lifted out of the brackets 74. Indexing mechanism M. (Figs. 2 and 6). This comprises an actuating member 412, a first device 410 for moving the member 412 lengthwise to engage it with and disengage it from each mould assembly 14 in turn, and a second device 414 for swinging the member 412 from a first position (Fig. 6) to a second position (Fig. 7, not shown), and back again for advancing the mould assemblies to the next station. One end of the member 412 is pivoted to a slide 418 which can be moved to and fro by pistons in cylinders 422, 424. The other end of the member 412 is adapted to engage between plates 430 secured to the mould assemblies. If the member 412 overshoots the position shown in Fig. 6, a plunger 456 in an hydraulic cylinder 458 brings it to rest and then " inches " it back to its correct position. Turret-locking mechanism 460 (Fig. 6, and Fig. 11, not shown), is arranged to act on the member 412. Injection.-The injection nozzle 12 comprises a valve which is normally closed but is opened when pushed rearwardly by contact with the mould. If desired, a mould may be presented to the injection nozzle 12 without automatic operation of the injection screw, by moving an arm 506 so that an abutment 508 contacts a depending arm 500 of a microswitch L14 as shown in Fig. 5. A selector switch determines whether injection takes place after a desired pressure build-up in the injection cylinder or whether injection and screw rotation start simultaneously. Control.-Figs. 13, 14 (not shown), illustrate hydraulic and electric control circuits for automatic operation of the machine. Four indexing buttons B4, B5, B14, B15 (Fig. 2), must be operated (two by each operator) to initiate an indexing operation.