Patent GB-1185343-A (GB)
Title: Heat Sealing Process and Apparatus.
IPC: B29C65/02
Filed: 1967-06-09
Abstract: 1,185,343. Seaming non-metallic sheet material; making bags. WINDMOLLER & HOLSCHER. 9 June, 1967 [27 June, 1966], No. 26691/67. Headings B5D and B5K. In a process of making bags by forming heatsealed end seams in flattened tube sections 30 of plastics material which each have an open end continuously moved past a stationary source 45 of radiant heat, whereafter the fused bead is consolidated by pressure, the end portions 47 to be heat-sealed of the sections 30 are arranged to lie one behind the other in planes which are at right angles to the direction of movement of these ends past the source 45 and are held in such manner by plates 16, 16<SP>1</SP> that these ends 47 protrude from the plates 16, 16<SP>1</SP> towards the source 45; the sections 30 are subsequently pulled to move the fused bead between the plates 16, 16<SP>1</SP> which are slightly spaced apart; and the plates 16, 16<SP>1</SP> are then pressed against the heat-sealed seams to consolidate them. As shown in Figs. 1 and 2, the plates 16, 16<SP>1</SP> are shorter than the sections 30 and are mounted to project from two endless chains 5, 51 extending around sprockets 1, 1<SP>1</SP>, 2, 2<SP>1</SP> 3, 3<SP>1</SP>, 4, 4<SP>1</SP>, the latter pair being mounted in levers 7, 7<SP>1</SP> for tensioning the chains. Springs 27 urge each upper plate 16 away from a lower fixed plate 16<SP>1</SP>. Freely-rotatable rollers 19 are mounted to protrude from the forward edge 22 of each plate 16<SP>1</SP>. The plates 16, 16<SP>1</SP> of a pair are spaced so that in the straight portions of the chains 5, 5<SP>1</SP> the adjacent plates 16<SP>1</SP>, 16 of two pairs resiliently engage each other but at arcuate portions the adjacent plates of two pairs are spaced apart. A section 30 is fed between adjacent plates 16<SP>1</SP>, 16 of two pairs as the chains 5, 51 pass around the sprockets 1, 1<SP>1</SP> and engages a stationary stop 32. The end which is not to be sealed drops on to a table 33 or on to the preceding section 30. The plates 16, 16<SP>1</SP> are closed to grip the section as the chains 5, 5<SP>1</SP> enter a straight section. A series of parallel belts 40 driven at the same speed as the chains 5, 51 and passing around pulleys 34, 35, 36, 37, 38, 39 of which the pulleys 37 are mounted in levers 41 adjustable to tension the belts which travel close to the plates 16, 16<SP>1</SP> on their path from the sprockets 1, 1<SP>1</SP> to the sprockets 3, 3<SP>1</SP>. The heating device 45 is provided with radiators 46 in a double-walled box 48, 49 movable about pivots 50, 51 when the machine is stopped to prevent excessive heating of the sections 30 and the plates 16, 16<SP>1</SP>. The radiators 46 extend transversely to the direction of travel of the sections 30 and fuse the ends 47 thereof. If each section 30 is formed with side gussets the end portions of the radiators 46 are designed for a higher heat output than the intermediate portions thereof. As the chains 5, 5<SP>1</SP> pass around the sprockets 2, 2<SP>1</SP>the adjacent plates 16<SP>1</SP>, 16 of two pairs become slightly spaced apart and as each section 30 is held between rollers 19 and the belts 40 the fused bead on the end 47 slides between the plates 16<SP>1</SP>, 16 which are then moved together to compress and cool this bead. When the chains 5, 5<SP>1</SP> pass around the sprockets 3, 3<SP>1</SP> the sections 30 remain on the belts 40 and are moved to a delivery point 53. In a modification of the heating device, Fig. 5, radiators 56 extend in the direction 55 of travel of the sections. If each section is formed with side gussets 57, 58, then the radiators 56<SP>1</SP> adjacent these gussets are designed for a higher heat output than the other radiators. The radiators are preferably arranged for individual energization and/or temperature control.