Patent GB-959087-A (GB)
Title: Improvements in machines for forming articles from thermoplastic sheet
IPC: B30B15/28
Filed: 1960-09-01
Abstract: 959,087. Moulding hollow articles. ILLINOIS TOOL WORKS Inc. Sept. 1, 1960 [Sept. 17, 1959], No. 30202/60. Heading B5A. [Also in Division B6] A machine for making articles, e.g. plastic cups from a sheet 33 of thermoplastic material e.g. polystyrene, comprises male and female moulds 42, 44, and actuating means for moving the male and female moulds towards and away from the sheet 33, characterized in that both the actuating means are resiliently mounted to accommodate a jam-up of sheet material without damage to the machine. The actuating means comprises cams mounted on shafts 78, 86, which are driven from an electric motor through gearing (not shown) that includes a flexible coupling of lugs on a driving member engaging in slots in a driven member. The contra-rotating shafts 78, 86 are mounted at their ends in spheroidal bearings so that a rather large deflection of the centres of the camshafts can be accommodated in the event of a jam-up of material. The mould 44 consists of a plurality of cavities 131, Fig. 24, mounted on a plate 134, slidable on bars 148 and connected to a carriage 136 which follows the movements of cams 144. The height to which the cavities rise is governed by the thickness of the split rings 152. The movements of a lower clamping plate 96 are also governed by a cam 126, Fig. 22, on the shaft 78. The male mould consists of a plurality of mandrels 166 on a plate 42, slidable on bars 148 and fixed to a carriage 170 which follows the movements of cams 175, 176. The depth to which the mandrels descend is governed by the thickness of split rings 180. Core plugs 156, Fig. 24, which form the bottoms of the cavities 131 bottom on a fixed plate 154 (not shown in Fig. 1) when the mould 44 is in its lowest position. A sheet of material 33 is fed into the machine through aligning means 36 and then through a feed control means 198 to a moving clamp means 199. The aligning means comprises two bars (as 200) which are pivoted (as at 196) and spring-biased to engage with both sides of the sheet to centre it. The moving clamp consists of two endless bandsaws (as 259) engaging one with each edge of the sheet and running round idler wheels (as 261) and driving wheels (as 263). The bandsaws are held in contact with the sheet 33 by rollers mounted on spring-biased plates 279. The bandsaws are driven by a continuously running electric motor through an electromagnetic clutch and shafts (as 265). The driving wheel 263 contains a friction clutch device, which slips in the event of a jam-up of material. The distance between the bandsaws and their tension is adjustable on bars 295, 296. As shaft 78 rotates, the cam 306 closes switch 308 which energizes the electromagnetic clutch and the sheet 33 is drawn into the machine by the bandsaws. This causes spring tensioned knurled wheels 230 to rotate and a cam fixed to the same shaft as the wheels 230 operates a switch (not shown) to stop the bandsaws after the passage of a predetermined length of sheet material. The sheet is heated by a heater 322 hinged at 328 and counterbalanced by a weight 349, so that the heater can easily be manually raised out of position in the event of a jam-up of material. In operation, the starting point of a cycle is shown in Fig. 24, where articles 32 formed by the preceding cycle are blown out of the machine by a blower 50. The lower clamping plate 96 is raised to grip the sheet against a fixed upper clamping plate 183. The male and female moulds are moved to the position shown in Fig. 22, where the sheet is clamped by the edges 190 of mandrel hoods 188, and blowing air is applied to form the articles inside the mould cavities. The sheet becomes cooled on contact with the cavities and the hoods 188 are moved slightly downwards to sever the articles from the sheet. The moulds and mandrels are then moved to the position shown in Fig. 24, and the plugs 156 bottom on the plate 154 to remove the articles from the mould cavities. Specification 959,088 is referred to.