Patent GB-478908-A (GB)
Title: Improvements in method and apparatus for moulding articles such as rubber heels
IPC: B29D35/12
Filed: 1936-12-29
Abstract: 478,908. Moulding and vulcanizing rubber heels &c. UNITED STATES RUBBER PRODUCTS, Inc. Dec. 29, 1936, No. 35615. Convention date, Dec. 30, 1935. [Classes 70 and 87 (ii)] [Also in Group XI] A method of moulding articles such as rubber heels comprises compressing material in a mould having relatively movable parts 32, 33, 84, moving the material and parts of the mould to free the compressed material at one side of the mould and operating the parts to trim off surplus material at the opposite side of the mould. The machine comprises a number of moulding devices mounted on a table 19 rotated about a central shaft 18 by gearing from an electric motor. Each moulding device comprises a standard 29 wherein slides a plunger 31 carrying the top mould part 32. The bottom mould part 33 comprises a plate 83 fixed to the table 19 and the intermediate part 84 pivoted to the plate 83, the pivot having elongated slots permitting upward movement of the part 84. A mould cavity 34 is provided by the part 84 and, for rubber heels, has flaring walls 36 and a straight wall 37 with a bevel 38. The top part 32 carries a convex presser head 39 which is curved from side to side and front to rear, but has one edge 40. The mould parts are heated for vulcanizing by electrical units 102, 103 located in cavities in the mould supports. The supply is distributed in four circuits each comprising a group of heating units which are connected to brushes on a shaft which rotates with the table 19 around eight collector rings connected to supply. Thermostat bulbs 118, 123 enable the temperature to be controlled from two switchboards. In operation, a rubber blank is placed on each plate 83 as it moves past an operator. The blank may be provided with a central stud 120 which is placed first in a recess 131 in the plate 83. The presser head 39 is moved down to compress the blank, pressure being also generated by heat, so that surplus material extrudes as at 127 and may also issue between the parts 83, 84, a groove 135 being provided on the plate. 83 to receive such surplus. For trimming, the presser head 39 is moved down slightly further so as to cut off the material between the edge 40 and the bevel 38 and also at the upper edge 136 of the mould part 84. In order to permit further movement, the part 84 is slightly raised from the part 83 so as to release the article from the part 83 and the article is forced down somewhat and released from the side walls. The top part is finally raised and the mould part 83 is swung over by means of a hooked tool and the article ejected. The presser head is moved down by a plunger 31 guided by the standard 29 and operated by a toggle 54, 57. The toggles are connected by rods 61 to rods 63 sliding in radial bearings in a cylindrical housing 50 moving round with the table 19. The rods 63 carry rollers 65 engaging a cam disc 66 on the shaft 18. Each toggle link is pivoted to a block 53 adapted to slide between bars 47 fixed to the standard 29. The movement of each block 53 is adjusted by wedges 67, 68 interposed between the block 53 and a fixed spacer block 48. The wedge 67 is manually controlled by a handwheel 72 and determines the extent of the pressing stroke of the plunger. The trimming stroke is effected by movement of the wedge 68 and is operated from a cam disc 81 on the shaft 18 through push rods 78 sliding in radial bearings in the housing 50. The slight upward movement of the intermediate mould part 84 is effected by stems 91 on a carriage 90 passing through openings in the plate 19 and part 83 and engaging the part 84. The carriage is normally suspended from a hook 94, but at the required position, rollers 100, 101 on the carriage engage spaced circumferentially and radially staggered cam tracks 97, 98 on a standard. When the part 83 is raised, recesses in the cam tracks withdraw the toggles and operate the wedge 68. The mould parts are detachably secured to the plunger head and to the plate 19.