Machine for heat sealing thermoplastic bags

Abstract

Abstract 1,045,889. Packaging-machines. POTASSE ET ENGRAIS CHIMIQUES. Aug. 8, 1963 [Aug. 21, 1962], No. 31330/63. Heading B8C. [Also in Division B5] A machine for heat-sealing filled thermoplastic bags comprises a frame on which are mounted two endless belts 8 supported by rollers 9, 11 having substantially parallel axes and which belts are maintained in surface contact on a part of their travel; at least one pair of heating shoes 31a, 31b and at least one pair of cooling shoes 33a, 33b at least one shoe of each pair being freely mounted on the machine frame and urged towards the other to squeeze the parts of the belts 8 between them into contact; and a motor 4 to drive the belt 8 in synchronization so that the materials to be sealed are drawn along by the belts 8 between the shoes 31a, 31b and then between the shoes 33a, 33b. In the embodiment shown, a frame 3 is adjustably mounted on a base 1 and has a shoulder 5 carrying girders 12a, 12b supporting the vertical axis rollers 9, 11. The belts 8 are preferably made from wire gauze having a fine mesh and are coated, by spraying, with an anti-adhesive agent, e.g. polytetrafluoroethylene, on the side contacting the bags to be sealed. The rollers 9 are driven in opposite directions by a motor 4 through a chain 14, a sprocket 16, bevels 17, sprockets 18 and a chain 19 (the latter not shown). The rollers 11 are idle and are urged away from the rollers 9 by springs 26, the pressure of which is adjustable by screws 27, to hold the belts 8 taut. Each shoe 31a, 31b, Fig. 4, comprises a U-shaped frame 34a, 34b supporting a copper block 35 the outer face of which transmits heat to the adjacent belt 8. A refractory sole 38 having coil resistances 39 fitted therein is separated from the block 35 by a mica insulating sheet 41. Adjustable bolts 43 urge the block 35 outwardly until it is restrained by hooks 36. The inclination of the shoe 31a is adjustable by screws 46 and the shoe 31a is pressed towards the shoe 31b by an adjustable threaded rod 47. The shoe 31b is attached by stirrups 54 to arms 55 mounted on the girder 12b and urged against the shoe 31a by a threaded rod 57 acted on by a spring 61. The shoes 33a 33b, Fig. 5, are mounted on the machine frame similarly to the shoes 31a, 31b respectively, and each comprises a hollow copper block 66 cooled by circulating water. Pressure rollers 32 may be provided between the blocks 31a, 31b and the blocks 33a, 33b. One roller 32 is fixed and the other is spring- urged thereagainst. In use, the machine is moved on rollers 2, Fig. 1, to a conveyer on which the filled bags to be sealed are transported. The height of the frame is adjusted and the speed of the motor 4 is adjusted so that the speed of the belts 8 and the bags is the same. The conveyer feeds the bags between the belts 8 to effect sealing thereof. The machine may be constructed with two or more pairs of heating and cooling shoes. Also, instead of only one shoe of each pair, each shoe may be suspended and pressed against the other.

Inventors

• 👤 Pierre Jean-Louis

Bibliographic Details