Patent GB-1485132-A (GB)
Title: Manufacture of bags made by heat-sealing
IPC: B31B29/00
Filed: 1974-08-28
Abstract: 1485132 Making valve bags DAI NIPPON PRINTING CO Ltd 28 Aug 1974 [28 Aug 1973 (2)] 37622/74 Heading B5D [Also in Division B8]  In a square-bottomed valve bag, a valved end closure comprises two overlapping end closure sheets 6 and 7 heat sealed to upwardly facing surfaces of flaps (4, 4<SP>1</SP>), Fig. 2 (not shown), and to inwardly facing surfaces of triangular portions 2, 2<SP>1</SP> under which the sheets 6, 7 are tucked. The other end of the bag is closed by a single end closure sheet 8 similarly heat sealed to downwardly facing surfaces of flaps (5, 5<SP>1</SP>), Fig. 5 (not shown), and to inwardly facing surfaces of triangular portions 3, 3<SP>1</SP>. The outer surface of a tube from which the bag body is formed, has been treated by corona discharge.  A machine for making such a bag comprises a conveyer for moving flattened bag bodies which have been subjected to corona discharge, in succession from one operating station to another, arrangements for opening both ends of each flattened bag body to form said flaps (4, 4<SP>1</SP>), (5, 5<SP>1</SP>) and said triangular portions 2, 2<SP>1</SP>, 3, 3<SP>1</SP>, apparatus for inserting and heat sealing each of the closure sheets 6, 7 and 8, and a device which is interposed between bag body top end closure apparatus and bag body bottom end closure apparatus, for inverting each bag body in its own plane. The bag body conveyer, Fig. 7, comprises a reciprocable carriage 23 having rails 24, 24<SP>1</SP> which carry pairs of piston and cylinder assemblies 29, (29<SP>1</SP>), Fig. 8 (not shown), for moving opposed clamps (30), Fig. 8 (not shown), into and out of gripping engagement with bag bodies. Above the carriage 23, spaced stationary plates 21, 21<SP>1</SP> carry on their undersides cooperating fixed and movable clamps (34, 33), Fig. 8 (not shown), for gripping the bag bodies. In operation a bag body which is out from a web 1<SP>1</SP> of flattened tubular material and delivered through a slot 22 between the plates  21, 21<SP>1</SP>, is advanced to successive stations II, III &c. by being alternately gripped and released by the clamps (30) on the carriage 23 and the clamps (33, 34) on the plates 21, 21<SP>1</SP> in sequence with reciprocation of the carriage 23. The arrangements for folding the bag body ends each comprise vacuum pads 35, 35<SP>1</SP> for pulling apart opposed peripheral portions of the bag body and a press roller 36 at the following station for folding and flattening the bag end against the plates 21, 21<SP>1</SP>. The apparatus for inserting and heat sealing the end closure sheets are each similar to the apparatus shown in Fig. 9 for inserting the sheet 6. The sheet 6 is clamped by fingers 44 on to a receiving plate 37 which is moved under the control of cams 59, 67 and 74 to insert the sheet 6 beneath the triangular portion 2. The receiving plate 37 carries a heat insulating sheet 41 and acts as a back-up member for a heat sealing member (not shown). The apparatus, Fig. 17 (not shown), for inserting the cover sheet 8 includes two such receiving plates (98, 98<SP>1</SP>) which support and insert simultaneously both ends of the sheet 8 beneath the respective triangular portions. The sheets 6, 7 and 8 are also heat sealed to the flaps (4, 4<SP>1</SP>, 5, 5<SP>1</SP>) by heat sealing members (not shown). The apparatus for inverting the bag bodies, Fig. 15, comprises a frame 76 which is oscillatable through 180 degrees by a rack and pinion arrangement 93, 84 and which has four pairs of parallel arms 77, 77<SP>1</SP>, 78, 78<SP>1</SP>, 79, 79<SP>1</SP>, 80, 80<SP>1</SP>. Each of the arms 77, 78, 79, 80 carries piston and cylinder assemblies 85, (86, 88), Fig. 16 (not shown), for clamping bag bodies received from the carriage 23 against the arms 77<SP>1</SP>, 78<SP>1</SP>, 79<SP>1</SP>, 80<SP>1</SP>. The operation of these piston and cylinder assemblies is controlled by a valve block 83 fixed to the drive shaft 82 for the frame 76. The inverted bag bodies are received by a further carriage 23 having arms 24, 24<SP>1</SP>.