Bag type shrink wrapping apparatus

Claim 2

Apparatus for enveloping a load carried by a pallet or other supporting base by opening out the lead end of a continuous roll of flat-folded tubular shrink-wrap film at a level above the load to be wrapped to a substantially four-sided configuration and then pulling the open end down over the load and heat-seaming and severing the folded film after a length sufficient to envelop the load comprising: a. a supporting frame having a top and vertical sides defining an open passageway therethrough with a load-supporting conveyor extending through the passageway centered between and spaced from the two sides, b. a four-sided carriage having sides and end members defining an area larger than the load to be wrapped mounted in the frame below the top and guided in the frame for vertical movement from an upper limit of travel below the top of the frame downwardly to about the level of the conveyor and constructed to clear a load to be wrapped which is positioned on the conveyor and centered under the carriage, c. the carriage being characterized by having two sheet-gripping bars movable sideways in opposite directions between a closed position where they are in spaced side-by-side position over substantially the center line of the conveyor to an open position where they are close to opposite sides of the frame, the said sheet-gripping bars being supported for such movement on the end members, and means on the carriage for effecting such movement of the gripping bars, d. the frame being characterized by having means thereon separate from said gripping bar moving means on the carriage for controllably moving the carriage up and down between its limits of travel, by having feed rolls at the top positioned to feed the flat-folded film from a supply source to the level of the sheet-gripping bars on the carriage when the carriage is in its uppermost position, means under the feed rolls and above the uppermost limit to which said gripping bars are raised when the carriage is at the upper limit of travel in the frame arranged to form a heat seam across the width of the film and cut-off means arranged to sever the film above the heat seam so formed, and a drive means arranged to rotate the feed rolls an amount only sufficient to advance the film in increments from the level of the cut-off means to the level where it may be engaged by the sheet-gripping bars when the carriage is at its uppermost limit of travel whereby the sheet-gripping bars may be moved to their closed position and engage opposite sides of the flat-folded film and then move to their open position to open the lead end of the film into a four-sided configuration and hold it open as the carriage is then moved from its upper limit of travel to its lowermost limit of travel

Claim 3

Apparatus as defined in claim 1 wherein the gripping bars are arranged to grasp and clamp the surfaces of the film which they engage to pull the film through said rolls when the carriage travels downwardly, and means arranged to separate said feed rolls and provide free rotation thereof independently of said drive means when the film is pulled in this manner, and means for effecting release of the film from said gripping bars when the carriage reaches its lowermost limit of travel.

Claim 4

Apparatus as defined in claim 1 wherein said opposed film sheet-gripping bars each comprises a bar having spaced suction cups therealong together with fingers movable from an open position below the suction cups upwardly in an arc into the interior of the tubular film to a closed position to clamp a single thickness of the film against the bar after its end has been drawn to the bars and partially opened by the suction cups, and operating means arranged to selectively move the fingers to grip the film and to release it.

Claim 5

Apparatus as defined in claim 3 in which said fingers are carried on a common rock shaft which is mounted on and extends along the bar parallel therewith, there being one finger on the bar positioned to cooperate with each suction cup when it is in sheet-gripping position, and means for rotating the shaft through a vertical arc of about 90* to move the fingers between the film-gripping and the open position.

Claim 6

Apparatus as defined in claim 4 wherein each of said bars has a means mounted thereon for effecting said rotation of the rock shaft associated with it.

Claim 7

Apparatus as defined in claim 1 wherein there is means on the frame comprising a vertically movable electric eye at one side of the conveyor past which the load moves to a position in the frame where it will be wrapped and a vertically elongated light source directed toward said electric eye for gauging the height of the load, and contact means movable vertically with the electric eye but in the opposite direction, aid contact means being arranged to be engaged by the carriage as it moves downwardly to determine a level between the top and bottom limits of the movement of the carriage to momentarily stop its continued downward pull on the continuous film while the said means for heat-seaming and severing the film operates to cut off a length of film required to envelop the load and provide a closed seam to eventually be positioned along the top of the load.

Claim 8

In an apparatus for enveloping a load which is carried on a pallet with a length of tubular shrink-wrap film by first opening out of the lead end of a flat-folded tubular wrapper at a level above the load to be wrapped and then pulling it down over the load, a. a supporting frame having a top and sides, b. means below the top of the frame positioned between but spaced from the sides thereof on which the load to be wrapped along with its pallet or other base is supported, c. power-driven means for feeding the lead end of a continuous flat-folded tubular film from a roll which is supported for rotation downwardly from the top of the frame in a vertical plane which is centered over the load-supporting means and termining such downward feed at a level above the top of a load positioned on said load-supporting means, d. a pair of opposed tube-gripping bars movable horizontally between an open position near the sides of the frame to a tube-gripping position where they confront each other with Said lead end of the flat-folded tubular film sheet intervening, said bars having means for drawing the opposite faces of the flat-folded tubular sheet apart and releasably gripping them comprising suction means and a plurality of movable film-pinching fingers with operating means for said fingers. e. means for simultaneously moving both of said bars from the open position to said tube-gripping position and then moving them apart to the open position while the film is gripped thereby to open said lead end of the sheet film to a four-sided configuration, f. carriage means movable vertically in the frame and in which said bars are moved and guided for movement toward and away from each other and means for effecting movement of said carriage means between an upper limit at a level above the load to be wrapped to a lower limit ofttravel at a level where the bars in the open position, but still gripping the film, have drawn the film down around the load which is positioned on the load support, g. means for operating the tube-gripping means on said bars to grip the opposed faces of the flattened film when the bars are in tube-gripping position and releasing them when said bars have been moved to the lower limit of their travel, h. means on the frame adjacent the conveyor where it enters the frame for gauging the height of each load as it moves toward said central position wherein the load height-gauging means comprises an elongated vertical light source at one side of the conveyor and an electric eye at the other side with means for raising the eye when a load is carried by the conveyor between the eye and the light source and which is controlled by the eye to stop the upward travel of the eye when the light strikes the eye over the top of the load, the carriage having a switch thereon and means in the path of downward travel of the carriage that is moved down with the upward movement of the eye arranged to engage said switch to stop the downward travel of the carriage at the level where the transverse seal and severing of the film sheet should be made for the height of the load to which the operation of the eye is related.

Claim 9

In an apparatus for enveloping a load which is carried on a pallet with a length of tubular shrink-wrap film by first opening out of the lead end of a flat-folded tubular wrapper at a level above the load to be wrapped and then pulling it down over the load, a. a supporting frame having a top and sides, b. means below the top of the frame positioned between but spaced from the sides thereof on which the load to be wrapped along with its pallet or other base is supported, c. power-driven means for feeding the lead end of a continuous flat-folded tubular film from a roll which is supported for rotation downwardly from the top of the frame in a vertical plane which is centered over the load-supporting means and termining such downward feed at a level above the top of a load positioned on said load-supporting means, d. a pair of opposed tube-gripping bars movable horizontally between an open position near the sides of the frame to a tube-gripping position where they confront each other with Said lead end of the flat-folded tubular film sheet intervening, said bars having means for drawing the opposite faces of the flat-folded tubular sheet apart and releasably gripping them comprising suction means and a plurality of movable film-pinching fingers with operating means for said fingers. e. means for simultaneously moving both of said bars from the open position to said tube-gripping position and then moving them apart to the open position while the film is gripped thereby to open said lead end of the sheet film to a four-sided configuration, f. carriage means movable vertically in the frame and in which said bars are moved and guided for movement toward and away from each other and means for effecting movement of said carriage means between an upper limit at a level above the load to be wrapped to a lower limit ofttravel at a level where the bars in the open position, but still gripping the film, have drawn the film down around the load which is positioned on the load support, g. means for operating the tube-gripping means on said bars to grip the opposed faces of the flattened film when the bars are in tube-gripping position and releasing them when said bars have been moved to the lower limit of their travel, h. means on the frame adjacent the conveyor where it enters the frame for gauging the height of each load as it moves toward said central position wherein the load height-gauging means comprises an elongated vertical light source at one side of the conveyor and an electric eye at the other side with means for raising the eye when a load is carried by the conveyor between the eye and the light source and which is controlled by the eye to stop the upward travel of the eye when the light strikes the eye over the top of the load, the carriage having a switch thereon and means in the path of downward travel of the carriage that is moved down with the upward movement of the eye arranged to engage said switch to stop the downward travel of the carriage at the level where the transverse seal and severing of the film sheet should be made for the height of the load to which the operation of the eye is related.