GB728239A - Improvements in or relating to a machine for and method of vacuum packing a product - Google Patents

Abstract

728,239. Sealing bags. EMHART MANUFACTURING CO. Sept. 11, 1952 [Sept. 26, 1951], No. 22874/52. Class 94 (1). A method of packaging commodities in flexible wall open-mouth bags containing a selected quantity of the commodity with a head space above the commodity comprises withdrawing gases from the bag through a nozzle to cause collapsing of the bag walls and elimination of the head space, flattening and gripping the bag mouth about the nozzle and sealing the bag while in position on the nozzle, spreading the bag walls defining the head space in a transverse zone removed from the nozzle, flattening and gripping the bag walls in a second transverse zone about the nozzle, and effecting sealing along a transverse line in the first zone while the bag is in the flattened, stretched condition. A bag 3, containing a food &c. product is mounted on a table 1 which is adjustable with respect to a table 14, and a stop 2 holds the bag away from a vacuumizing assembly 4. The bag is placed on a plate 20 slidable on a rod 23 secured to bars 18, 19, and the plate is urged rearwardly by a spring. For large packages a stop 2<SP>1</SP> may be secured to the plate. Heat sealer. A transversely extending sealing unit 11 is fixed on the table 14 and a similarly extending unit 10 is secured at its ends to posts 39, 40 which are -moved vertically between an upper position and a lower, or sealing position, by an air piston motor 42 which engages a cross-bar 41. The units comprise electrically heated metal bars to the sealing surfaces of which are secured pads of a non- sticking material. The vertical movements are cushioned by pairs of springs 43, 45, and the latter pair surround'rods 44 which engage the table 14 to limit upward travel. The units may be individually controlled by adjustable ther mostats. Vacuumizing assembly. Consists of a nozzle 5, spreader bars 6, clamps 7a, 7b and a tongue 8, and is mounted on a plate P which is arranged for pivotal tilting movement by means of a bearing bracket P<SP>1</SP> rotatable on a shaft 51 secured to the table 14. The tongue is secured to a rod 52 and is slidably mounted within the nozzle and includes air evacuating passages 53, 54 which communicate through the nozzle and a line with a vacuum tank connected to a pump. The spreader bars 6 are mount ed in eyes 93, 93a on levers 94 which pivot horizontally on vertical posts 95 secured to the plate P. The posts are' mounted in slots to allow adjustment of the post spacing. Springs 97 are tensioned between the levers and fixed arms 98 so that the bag mouth is stretched. The levers 94 include bell crank portions with rollers 101 which are normally engaged by bell cranks 102 so that normally the levers and spreader bars point inwardly and rest against the nozzle 5. Clamping means. Clamps or jaws 7a, 7b comprise rubber pads 72a backed by metal bars 72b secured to brackets 72c. The lower brackets are secured to spaced levers 72 secured to a shaft 73 journaled in bearings on the plate P, and these levers are connected by adjustable turnbuckles 77 with upper jaw levers 74 mounted on a shaft 75 on the said plate. Clamping pressure is applied by an air operated piston motor 78 secured to the plate, the piston thereof acting through levers 81, 82. Operation. When the bag mouth is placed over the nozzle and spreader bars the starter switches 86, 87 are made and the motor 78 is operated via a solenoid operated valve to clamp the bag mouth between the jaws 7a, 7b. When the jaws start to close the arm 82 rotates the cranks 102 and the bars 6 are spread against the bag mouth. The operator then moves a transverse bar 59, and cranks 60 which are secured thereto are pivoted about a shaft 61 to close a switch 65. The latter energizes a solenoid 66 to connect the vacuum line from the nozzle to the tank. The solenoid has an armature 66a which operates a crank 68 which opens a vacuum valve 57a. An arm of the crank with a part 68b providing a safety catch normally engaging the cross-bar 41 and preventing downward movement of the upper sealing unit is also moved to allow such downward movement. As the sealing unit 10 moves downwardly pins 30 thereon engage cranks 27 on a transverse rod 28 to which are connected rods 26, 26a, so that rotation of the cranks moves the plate 20 forwardly, and the stop 2 on rod 28 also moves forward slightly prior to sealing. The plate 20 is normally restrained in the rearward position by locking pawls which are moved by the pins 30 from detents to allow this forward movement. The tongue and spreader bars are automatically retracted out of the path of the heat sealing unit by means of a transverse bar 106 supported on rails. The tongue rod 52 is secured to the bar and the spreader bars are adjustably secured thereto, and the bar 106 is retracted by means of a bell crank 112 pivoted on the shaft 51. The crank 112 has forked rams 112a with rollers which engage the bar 106 and an arm 112b with rollers which engage a rod 117. The latter slides vertically in a guide 118 fixed by a bracket to the posts 39, 40 so that as the sealing unit moves downwardly a pawl 120 on the guide engages the lower end of the rod 117 to move it downwardly and the tongue and spreader bars are thereby retracted. To prevent further downward movement of the sealing unit the pawl is retracted by a plate 120c and the guide then engages a spring 117b. The bag mouth is pulled from the hot sealed portion whilst the latter is held between the sealing units by the tilting of the plate P by means of an air piston motor 121 secured to the table 14. A piston rod 122 is connected by a link 123 with a part 80 depending from the plate P, and the motor is operated through a solenoid operated valve which, in turn, is operated when the sealing unit is lowered. When the piston rod is at the limit of its tilt-up stroke a switch 129 is operated to energize a tilt-down solenoid, a clamp opening solenoid, and a solenoid for initiating upward movement of the sealing unit. The upward movement initiates, through a switch, a flow of air to the nozzle 5 to eject the bag remnant 3b. This air flows through passages 71 in the nozzle and it may also pass through the suction passages.