Patent GB-1352143-A (GB)
Title: Machines suitable for use in carrying out hf welding operations on workpieces
IPC: B29C65/04
Filed: 1970-03-10
Abstract: 1352143 Seaming, laminating BRITISH UNITED SHOE MACHINERY CO Ltd 19 April 1971 [10 March 1970] 11307/70 Addition to 1267953 Headings B5K and B5N [Also in Divisions F2 and H5] A welding and cutting machine comprises means 110, Fig. 2, for effecting relative movement of approach between an upper platen 104 and a workpiece supporting surface provided by a lower platen 44 whereby when in use, a tool can be pressed against a workpiece on the supporting surface, and connecting means whereby the platens, which serve also as electrodes, can be connected to a high frequency electric source so that when the tool is pressed against the workpiece a H.F. operation can be effected on the workpiece. The machine has a bed 30 supported by legs 32, Fig. 1, and carrying uprights 36 secured to a cross beam 38. Two lower platens 44 are mounted one on each side of the bed and consist of aluminium blocks having thin sheets of aluminium 46, Fig. 2, on their upper surfaces, each platen providing an operating station and having a locating means 48, Fig. 8, for supporting a tool and for positioning a workpiece, the locating means being mirror images of one another. The right hand locating means consists of a block 50 secured to the upright 36 and pivotally mounting a plate 52 which in turn pivotally supports an arm 54. A spring 68 acts to urge the arm clockwise, the force exerted by the spring being adjustable by a screw 58. A flange 70 in the arm provides a support for a die 76 mounted on the flange by bolts 72 and locating pins 74. The die consists of a plate 78 of insulating material one margin of which has holes for the bolts and pins and a backing strip 80 of steel. The plate also carries blade portions 82 for H.F. and cutting operations on the workpiece; the blade portions may define a pair of shoe components and are backed by a steel plate 84. The arm 54 is releasably retained in its operative position, as shown, by a latch mechanism 88. The workpiece is positioned on the platen 44 by a sheet 100 of pattern board having a cut-out shaped to a "caster" shape constituting the workpiece, the sheet being located on the aluminium sheet 46 of the platen by locating pins. During H.F. operation, a barrier sheet of insulating material is placed between the workpiece and the sheet of aluminium. The upper platen 104, Fig. 2, is movable between the two operating stations and consists of an aluminium plate secured by insulation 106 to a plate 108 carried by an hydraulic ram 110 from a carriage 112 provided with rollers running on rails on the beam 38, the carriage being movable along the beam by a chain 114 (Fig. 1) entrained around sprockets, one of which is driven by a motor. The ram is operative to lower the platen for a working operation, the platen then being raised by springs contained in tubes 116. The means connecting the platens to the H.F. eource 42, Fig. 1, consists of a copper strip 122, Fig. 3, extending from the source to an upstanding blade 124 at the rear centre of the machine. A frame member 128 extends across the rear of the upper platen and at each end has a post 130 having a vertically adjustable bracket 132 provided with a contact member 134, the members selectively engaging the blade 124 according to which of its two operating positions the platen is placed. Each bracket is individually adjustable to control the position of its contact relative to the blade so that the power applied to the platen is independently adjustable for each of the operating positions of the upper platen. The voltage distribution over the area of the upper platen can be tuned independently for each operating station according to the dies used at the stations. The tuning means consists of a contact member 162, Fig. 2, mounted at each end of the upper platen 104, and a contact blade 164 at each operating station, each blade being mounted by an insulating blade 166 to an upright 36 of the machine, the blades 164 being selectively engaged by the contact members 162 when the platen is in one or other of its operating positions. Each insulating blade is secured to one end of a pair of bars 174, 176, Fig. 7, the opposite ends being mounted in an insulated lug 178 on the machine bed 20. Each upper bar 174 is connected to its respective blade 164, and each lower bar 176 is connected to its associated lower platen 44 by a copper strip 180. A slide blade 184 is adjustably mounted in each pair of parallel bars whereby the voltage distribution at each station can be tuned independently of that at the other station. The machine has two end guards 194, Fig. 1, a top guard 196, a guard 198 secured by brackets to the support plate 108 of the upper platen, and a guard 202 movable to each of the operating stations. A rubber block 204 between the lower platens prevents access to one station when the other is exposed. The upper part of the guard 202 is mounted by upper and lower rollers 206, 208, Fig. 2, on a rail 210 fixed to the beam 38, and the lower part has rollers running in a rail on the bed 30. A mechanism 200 at each end of the beam releasably looks the guard 202 in each of the operating positions and consists of a spring-loaded latch 224 for receiving a collar on a lower roller 208. A pair of micro-switches actuated by pivoted levers 240 are mounted on a bracket 238 at the centre of the beam 38, the switches being selectively operated by fingers 244 one at each end of the guard. A flange 248 at each end of the guard is provided for movement of the guard between the operating stations. The machine is controlled so that with the guard 202 and upper platen at one station, a workpiece and die can be set at the other station, movement of the guard to the other station automatically causes the upper platen to be moved to the other station, lowered by the ram 110 for an H.F. and/or cutting operation and returned to its upper position by the springs whereupon a workpiece and die can be set at the said one station so that when the guard 202 is moved to that station, the upper platen is then automatically moved to that station to effect a working operation. The machine can be set to work at a single or both operating stations and to effect both H.F. and cutting operations, an H.F. operation only or a cutting operation only. The welding operation may be effected on layers of thermoplastic material or upon other material having a heatactivatable adhesive between the layers.