Apparatus for shrink-wrapping

Claim 2

Apparatus for enveloping a load carried on a pallet or other base member in a shrink-film wrapping comprising: a. a machine structure having upright structural sections and cross members connecting the tops of the upright sections and having means positioned within said structure on which a load to be wrapped is supported, b. means on said machine structure for feeding a flat tubular plastic shrink film downwardly toward a load positioned on said load-supporting means, c. side frame members movable vertically in said machine structure between a normal raised position at a level extending above the top of a load on said load-supporting means to a level extending below the bottom of said load, one of said movable side frame members being movable in a plane at one side of a load on said load-supporting means and the other in a plane at the opposite side, And d. sheet gripping means for gripping and partially opening the lower end of the tubular wrapper and mechanical clamping elements on each of the movable said frame members for positively clamping the partially opened tubular wrapper and movable laterally away from each other from an initial clamping position close to the plane of the descending tubular wrapper to a position where said clamping elements will clear the sides of the load on said load-supporting means when said side frames are lowered from said normal raised position to their lowermost position.

Claim 3

Load enveloping apparatus as defined in claim 1 wherein means is provided for simultaneously moving the mechanical clamping elements away from each other at substantially the same time and rate.

Claim 4

Load enveloping apparatus as defined in claim 1 wherein said sheet gripping means are mounted opposite each other on either side of the descending tubular wrapper and wherein the mechanical clamping elements on one side frame member are opposite those on the other side frame member whereby opposite faces of the flat tubular wrapper can be gripped and initially opened by the sheet gripping means and can be fully opened as said clamping elements move away from each other.

Claim 5

Load enveloping and wrapping apparatus as defined in claim 3 wherein there are at least two of said mechanical clamping elements on each side frame positioned to clamp opposite faces of the flattened tube near the side edges thereof to open the tube into a four-sided envelope.

Claim 6

Load enveloping and wrapping apparatus as defined in claim 1 in which said tubular sheet gripping means and said clamping elements are carried on the free ends of arcuately movable members pivotally supported on said vertically-movable side frames, said arcuately movable members being movable in an arc from a horizontal position where the gripping means and the clamping elements on opposite side frames most closely approach each other downwardly and outwardly relatively to each other through an arc of about 90*.

Claim 7

Apparatus as defined in claim 5 in which the gripping means and the clamping elements are rotatably mounted on the outer ends of said arcuately movable members, and means for rotating the gripping means and the clamping elements in a direction opposite the direction of arcuate travel of said arcuately movable members to keep the angular relation of said gripping means and said clamping elements constant in respect to the original vertical plane of said flat tubular sheet as it is fed downwardly into the machine.

Claim 8

Apparatus as defined in claim 5 in which there are fluid pressure cylinder and piston units on the side frames arranged to effect the swinging movement of said arcuately movable members.

Claim 9

Apparatus as defined in claim 1 in which said side frame members are guided for vertical movement in said upright structural sections of said machine structure.

Claim 10

Apparatus as defined in claim 1 in which there is a driving means arranged to move said side frame members vertically in synchronism and isochronism.

Claim 11

Apparatus as defined in claim 1 in which said sheet gripping means and said mechanical clamping elements are combined and each comprise: a. a suction nozzle arranged to draw a portion of the tubular sheet material into it, b. clamping means associated with said nozzle for gripping and holding the portion of the tubular sheet which is sucked into the nozzle, and c. means for controllably operating said clamping means to clamp or release the tubular sheet.

Claim 12

Apparatus as defined in claim 10 in which said clamping means comprises a movable clamping block mounted in the nozzle and said last-named means comprises a fluid pressure cylinder and piston unit operatively connected with the clamping block.

Claim 13

Apparatus as defined in claim 10 in which each side frame member includes a supporting bar extending in the direction of the length of said side frame members, said supporting bars each having a plurality of Said combined sheet gripping means and clamping elements thereon.

Claim 14

Apparatus for enveloping a load to be packaged with a length of tubular shrink-wrapping material by opening out a flattened tubular wrapper at a level above the load to be wrapped and then pulling it down from above the load around the load, said apparatus comprising: a. a supporting structure through which a load-conveying and supporting conveyor passes. b. vertically movable side frames in said supporting structure extending parallel with the conveyor, one at each side of the conveyor, c. means for raising and lowering the side frames in unison from a level where they extend above a load positioned on said conveyor to be wrapped to a level extending below the load, d. each side frame having wrapper-vacuum gripping and mechanical clamping means thereon supported for movement on the frame toward and away from the longitudinal central plane of the conveyor, and e. means for feeding a flattened tubular wrapping strip vertically from the top of said supporting structure down between said vacuum gripping and mechanical clamping means when the side frames are raised and the vacuum gripping and mechanical clamping means of the two side frames are extended to a position nearest said central plane.

Claim 15

Apparatus for enveloping a load to be packaged with a length of tubular shrink-wrapping material by opening out a flattened tubular wrapper at a level above the load to be wrapped and then pulling it down from above the load around the load, said apparatus comprising: a. a supporting structure through which a load-conveying and supporting conveyor passes. b. vertically movable side frames in said supporting structure extending parallel with the conveyor, one at each side of the conveyor, c. means for raising and lowering the side frames in unison from a level where they extend above a load positioned on said conveyor to be wrapped to a level extending below the load, d. each side frame having wrapper-vacuum gripping and mechanical clamping means thereon supported for movement on the frame toward and away from the longitudinal central plane of the conveyor, and e. means for feeding a flattened tubular wrapping strip vertically from the top of said supporting structure down between said vacuum gripping and mechanical clamping means when the side frames are raised and the vacuum gripping and mechanical clamping means of the two side frames are extended to a position nearest said central plane.

Claim 16

Apparatus for enveloping a load to be packaged with a shrink-wrapping material comprising: a. means for feeding a flattened tubular sheet of shrink-wrapping material from an overhead position downwardly toward a load to be wrapped, b. opposed vacuum gripping and mechanical clamping elements supported for simultaneous movement from an uppermost sheet gripping and clamping position in which said elements are in close confronting relation with clearance between them for the downwardly fed flattened tubular sheet downwardly and outwardly to a position of maximum separation and thereby pull said sheet open into a four-sided tube at a level above the load to be wrapped and further movable downwardly in parallel vertical planes from said position of maximum separation to a lowermost limit of travel, c. means for controllably effecting such movement of the vacuum gripping and mechanical clamping means, d. load supporting means positioned to hold a load to be wrapped substantially centered under said four-sided open tube with the top of the load at a level below said level of maximum separation and the bottom of the load above said lowermost limit of travel of said vacuum gripping and mechanical clamping means, and e. said vacuum gripping and mechanical clamping means being operable to grip and clamp the faces of the sheet in their uppermost position and operable to release said clamped faces in their lowermost position.

Claim 17

Apparatus for enveloping a load to be packaged with a shrink-wrapping material comprising: a. means for feeding a flattened tubular sheet of shrink-wrapping material from an overhead position downwardly toward a load to be wrapped, b. opposed vacuum gripping and mechanical clamping elements supported for simultaneous movement from an uppermost sheet gripping and clamping position in which said elements are in close confronting relation with clearance between them for the downwardly fed flattened tubular sheet downwardly and outwardly to a position of maximum separation and thereby pull said sheet open into a four-sided tube at a level above the load to be wrapped and further movable downwardly in parallel vertical planes from said position of maximum separation to a lowermost limit of travel, c. means for controllably effecting such movement of the vacuum gripping and mechanical clamping means, d. load supporting means positioned to hold a load to be wrapped substantially centered under said four-sided open tube with the top of the load at a level below said level of maximum separation and the bottom of the load above said lowermost limit of travel of said vacuum gripping and mechanical clamping means, and e. said vacuum gripping and mechanical clamping means being operable to grip and clamp the faces of the sheet in their uppermost position and operable to release said clamped faces in their lowermost position.

Claim 18

Apparatus as defined in claim 14 wherein said vacuum gripping and mechanical clamping elements each comprise a suction nozzle for drawing the wrapper sheet into it and movable clamping means selectively operable to mechanically hold the wrapper sheet when it has been drawn into the nozzle and to release it at the required time.

Claim 19

Apparatus as defined in claim 14 wherein said opposed vacuum gripping and mechanical clamping elements are mounted at the outer ends of swinging arm structures which are horizontal at said uppermost position of said elements and movable downwardly to said position of maximum separation, and said swinging arm structures are in turn each carried on a vertically movable side frame one of which is at one side of the load-supporting means and one at the other side.

Claim 20

Apparatus as defined in claim 16 wherein means is provided for rotating said vacuum gripping and mechanical clamping elements in a vertical arc in a direction opposite the direction in which said swinging arms rotate.

Claim 21

Apparatus for enveloping a load carried on a pallet or other base member in a shrink-film wrapping comprising: a. a machine structure having upright structural sections and cross members connecting the tops of the upright sectiOns and having means positioned within said structure on which a load to be wrapped is supported, b. means on said machine structure for feeding a flat tubular plastic shrink film downwardly toward a load positioned on said load-supporting means, c. side frame members movable vertically in said machine structure between a normal raised position at a level extending above the top of a load on said load-supporting means to a level extending below the bottom of said load, one of said movable side frame members being movable in a plane at one side of a load on said load-supporting means and the other in a plane at the opposite side, and d. sheet gripping and clamping elements on each of the movable side frame members movable laterally away from each other from a sheet gripping and clamping position close to the plane of the descending tubular wrapper to a position where said sheet gripping and clamping means will clear the sides of the load on said load-supporting means when said side frame members are lowered from said normal raised position to their lowermost position, the said sheet gripping and clamping elements on each movable side frame member each comprising means to first grip a surface of the flattened tubular sheet to initially effect partial opening of the tubular sheet as said elements move away from each other and means which is then operable to mechanically clamp the confronting surface of the partially opened tubular sheet and hold it clamped during the remaining lateral movement of said element and the entire downward travel of the side frame member on which said element is carried, and e. means for effecting simultaneous movement of the sheet gripping and clamping elements.

Claim 22

Apparatus for enveloping a load carried on a pallet or other base member in a shrink-film wrapping comprising: a. a machine structure having upright structural sections and cross members connecting the tops of the upright sectiOns and having means positioned within said structure on which a load to be wrapped is supported, b. means on said machine structure for feeding a flat tubular plastic shrink film downwardly toward a load positioned on said load-supporting means, c. side frame members movable vertically in said machine structure between a normal raised position at a level extending above the top of a load on said load-supporting means to a level extending below the bottom of said load, one of said movable side frame members being movable in a plane at one side of a load on said load-supporting means and the other in a plane at the opposite side, and d. sheet gripping and clamping elements on each of the movable side frame members movable laterally away from each other from a sheet gripping and clamping position close to the plane of the descending tubular wrapper to a position where said sheet gripping and clamping means will clear the sides of the load on said load-supporting means when said side frame members are lowered from said normal raised position to their lowermost position, the said sheet gripping and clamping elements on each movable side frame member each comprising means to first grip a surface of the flattened tubular sheet to initially effect partial opening of the tubular sheet as said elements move away from each other and means which is then operable to mechanically clamp the confronting surface of the partially opened tubular sheet and hold it clamped during the remaining lateral movement of said element and the entire downward travel of the side frame member on which said element is carried, and e. means for effecting simultaneous movement of the sheet gripping and clamping elements.