GB1235673A - Feed mechanisms - Google Patents

Abstract

1,235,673. Seaming non-metallic sheet material; cutting-out presses. B. A. GOUGH EQUIPMENT Ltd. 11 Nov., 1968 [10 Aug., 1967], No. 36755/67. Headings B4B and B5K. A machine for welding together two superposed lengths of thermoplastic material or a machine to cut out shapes from sheet material includes a mechanism for intermittently feeding sheet material through a work station which mechanism comprises a pair of first releasable gripping means 20, 21 located against movement forwardly and rearwardly, a pair of second releasable gripping means 38, 39 movable in synchronism both forwardly and rearwardly, one means of each pair being arranged in front of and the other to the rear of the work station, and actuating means for alternately (a) releasing the means 20, 21, operating the means 38, 39 to grip the material and moving the means 38, 39 forwardly and (b) operating the means 20, 21 to grip the material and to hold it at the work station, releasing the means 38, 39 and moving the latter rearwardly. As shown, a welding machine comprises a welding head 13 reciprocable by an hydraulic jack 14 towards and away from a table 12 mounted between rails 11. Each gripping means 20, 21 comprises a rod 22, 23 extending across the whole width of the table 12 and which is covered by a rubber sleeve 24. The ends of each rod receive vertical tappets 26, Fig. 2, which pass through apertures 12a in the table 12 and whose lower ends 27 engage, under the influence of springs 29, latch bars 28 reciprocable forwardly and rearwardly in the table. In the gripping position of the bars 28, the ends 27 are located in inclined wall recesses 32 so that the rods 22, 23 grip sheet material on the table 12. The bars 28 are provided with front and rear adjustable threaded abutments 46, 47, respectively. A reciprocable carriage 34 runs on rails 11 and comprises members 35, 36, 37. The second gripping means 38, 39 are mounted above the members 35, 36 and are constructed similarly to the means 20, 21. In operation, thermoplastic material from rolls on mountings 60, 61 passes over a tension roll 62, between the means 20, 21 and the table 12, between the means 38, 39 and the members 35, 36 and over a roll 63 which has been rotated to slightly tension the material. Initially, the carriage 34 is at the rear end of its stroke and ends 52 of the latch bars 45 of the means 38, 39 have engaged abutments 51 to cause the rubbercovered rods 40, 41 of the means 38, 39 to grip the thermoplastic material 19 against the members 35, 36. The carriage 34 moves forwardly and the length of material between the means 38, 39 is moved over the table top and beneath the means 20, 21 which are in their releasing positions. At the forward end of the stroke of the carriage 34, the carriage closes a microswitch to start a timer which energizes a valve to cause the welding head 13 to descend. As the head 13 descends it opens one microswitch and closes another to cause an hydraulic jack to reverse the direction of movement of the carriage 34 and to start the operation of a timer in the welding circuit. When ends 50 of the bars 45 contact abutments 49, the rods 40, 41 are released and, when an intermediate crossmember 48 engages the abutments 47, the rods 22, 23 are lowered to grip the material on the table 12. After a predetermined time interval, the head 13 is retracted and the welding circuit is turned off. As the carriage 34 reaches the rear end of its stroke, the ends 52 engage the abutments 51 so that the rods 40, 41 grip the material and the carriage member 35 engages the abutments 46 to lift the rods 22, 23. The cycle is repeated. Hydraulic and electrical circuits for the operation of the machine are described, Figs. 3 and 4 (both not shown).