WIPE DOWN ARRANGEMENT FOR WRAPPING APPARATUS

Abstract: An arrangement for wiping down a web wrapped on a load in­ cludes a wiper support; and a wiper including at least one strip (42), the strip extending from the wiper support and being flexible in a direction generally parallel to the thickness of the strip for wiping down the web wrapped on the load by relative movement between the wiper support and the web in said direction.

Description: The present invention relates to an apparatus as indicated in the precharacterising part of claim 1. Such an apparatus as disclosed in GB-A-2 021 510 comprises a web dispenser and a turntable for rotating a load relative to the web dispenser. After automatically wrapping a load with the film web, the trailing end of the web needs to be wiped down on the load so that it comes into contact vith and becomes adhered to an underlying layer of web. The wipe-down arrangement involves the use of a bristle brush attached to a support which moves relative to the trailing end of the web and the load. However, such an arrangement offers a number of drawbacks. Bristle brushes provide optimum stiffness only within a very narrow range of distances from the load. As a result, the positioning of the conventional bristle brush would have to be reset by wrapping loads of various sizes. This drawback is of particular significance in automatic, continuous wrapping procedures which would otherwise need little intervention by human operator. Another drawback is that the brush would generally need to be articulated about more than one axis in order to adequately position the brush relative to the web load. An additional drawback is that the bristles fatigue bend and sag after a period of use and, therefore, need to be replaced after such periods of use. A further drawback of the conventional brush arrangement is that the brush does not conform to the surface of products having a non-regular shape and, as a result, do not insure a complete wipe down along the whole width of the trailing end of the web. Another drawback is that the brush needs to encounter the web at a particular angle and with a particular motion in order to effectively wipe down the web and prevent the bristles from piercing and tearing the web. The patents GB-A-2 021 510 as well as US-A-4 300 326 assigned to Lantech, Inc. are incorporated herein by reference. It is the object of the invention to provide a wrapping apparatus having a secure operating wipe-down device for wrapping loads with an irregular shape or varied sizes. In accordance with the invention, this object is solved by the features as claimed in the characterizing part of claim 1. BRIEF DESCRIPTION OF DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention. Fig. 1 is a perspective view of a stretch wrapping machine with a wipe down device incorporating the teachings of the present invention; Fig. 2 is a perspective partial view of the wiper and wiper support in the arrangement illustrated in Fig. 1; Fig. 3 is a top view of the arrangement shown in Fig. 2 prior to engaging a load; Fig. 4A is a top view of the arrangement shown in Fig. 3 as it engages a narrow load; Fig. 4B is a top view of the arrangement shown in Fig. 3 as it engages a wide load; Fig. 5 is a top view of another embodiment of a wiper and wiper support incorporating the teachings of the present invention; Figs. 6A through 6D are schematic top views of the arrangement shown in Fig. 1 illustrating a sequence of operation; Fig. 7 is a perspective view of a stretch wrapping machine with a wipe down device incorporating the teachings of the present invention; Fig. 8 is a perspective partial view of the wiper and wiper support in the arrangement illustrated in Fig. 7; Fig. 9 is a top view of the arrangement shown in Fig. 8 prior to engaging a load; Fig. 10A is a top view of the arrangement shown in Fig. 9 as it engages a narrow load; Fig. 10B is a top view of the arrangement shown in Fig. 9 as it engages a wide load; Fig. 11A through 11B are top views of the arrangement shown in Fig. 9 illustrating a sequence of operations; Figs. 12A through 12D are schematic top views of the arrangement shown in Fig. 7 illustrating a sequence of operation; and Fig. 13 is a top view of another embodiment of a wiper and wiper support incorporating the teachings of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the present preferred embodiments of the invention as illustrated in the accompanying drawings. In accordance with the present invention, there is provided an apparatus for wiping down a web wrapped on a load comprising: a wiper support; and a wiper including at least one strip having two ends, a thickness, a width substantially greater than the thickness, and a length extending between the two ends, at least one end secured to the wiper support, the strip extending from the wiper support in a direction along the length of the strip and being flexible in a direction generally parallel to the thickness of the strip for wiping down the web wrapped on the load by relative movement between the wiper support and the web in said direction. As embodied and shown in Fig. 1, the apparatus for wiping down a web wrapped on a load is integrated into a stretch wrapping machine 20. Stretch wrapping machine 20 includes a conveyor 22 for conveying a pallet load 24 along its length. Pallet load 24 before being wrapped, may consist of a plurality of individual sub-units 26 which are stacked on a skid 28 so that they can be unitized by a web of plastic film which is wrapped on a pallet load 24 and skid 28 by the stretch wrapping machine 20. With reference to Fig. 1, pallet load 24 progresses along conveyor 22 in a generally left to right direction indicated by arrow A. Prior to achieving the position shown in Fig. 1, the stacked but unwrapped pallet load 24 stops on turntable 30, which is part of the conveyor 22. Turntable 30 rotates about a vertical axis to rotate pallet load 24 relative to film web dispenser 32, which is mounted on a frame 34 proximate to conveyor 22. Film web dispenser 32 is suspended by a support 36 which is attached to frame 34 by a rack and pinion drive mechanism to drive film web dispenser 32 in the vertical direction of arrow B along frame 34. This allows pallet load 24 to be wrapped along its full height when the width of the film web 31 is less than the height of the pallet load 24. Film web dispenser 32 dispenses film web 31 in a conventional manner. According to the present invention, the apparatus includes a wiper support. As shown and embodied in Fig. 1, the wiper support includes a horizontally extending arm 38 and a vertical support bar 40 mounted across one end. The other end of arm 38 is mounted on frame 34 through the use of vertical axle 54, so that arm 38 pivots through an arc of arrow C about a vertical axis. A hydraulic control cylinder 55 (partially obscured) also connects arm 38 and frame 34 and is used to position arm 38 during operation. According to the present invention, the apparatus also includes a wiper including at least one strip having two ends, a thickness, a width substantially greater than the thickness, and a length extending between the two ends, at least one end secured to the wiper support, the strip extending from the wiper support in a direction along the length of the strip and being flexible in a direction generally parallel to the thickness of the strip for wiping down the web wrapped on a load by relative movement between the wiper support and the web in said direction. As shown and embodied in Fig. 1, said at least one strip includes a plurality of strips 42 of ultra-high molecular weight plastic, such as those made by Dupont under the name Delron, Ertalon, and Ertalite. According to the present invention, it is preferable that the strip length is substantially greater than the strip width and the width is substantially greater than the strip thickness. As shown and embodied in Fig. 2, each strip 42 is about 15" long, 5" wide, and 1/16" thick. The length of the strip is determined by the ranges of variation in product size. Each strip 42 has two ends 44 and 46 along its width. It is preferable that only one end 44 is secured to the bar 40 of the wiper support and the other end 46 is a cantilevered free end. Fasteners such as rivets 48 can be used for this purpose. Because of the dimensions and mounting of the strip on the wiper support, the strip extending from the wiper support is flexible in a direction generally parallel to the thickness of the strip. Similarly, because of the dimensions and mounting of the strip on the wiper support, the strip is rigid about an axis extending in said direction. As shown in Figs. 1 and 2, the loop formed by strips 42 are rigid about an axis lying in a horizontally oriented plane. As a result, the strips 42 are extremely resistant to the effects of gravity and do not sag even after a prolonged period of operation. It is preferable that said at least one strip includes a plurality of strips mounted adjacent to each other along the wiper support in an array extending generally perpendicular to said direction and are spaced apart from each other. As shown and embodied in Figs. 1 and 2, strips 42 are mounted adjacent to each other in an array extending along the vertical extent of support bar 40, and are spaced from each other as to be independently movable, relative to each other, about a vertical axis. The use of wiper strips according to the present invention allows a series of loads of varying sizes to be wiped down in a continuous operation without adjusting or varying the wipe down arrangement. The multiple number of strips along the length of the support bar 40 also allows for automatic adaptability of irregular shaped loads. It is preferable that said at least one strip includes a plurality of strips mounted adjacent to each other in an array extending generally in said direction. It also is preferable that at least one of said plurality of strips extends farther from the wiper support than at least another one of said plurality of strips, that the strips are spaced from each other, and that the spacing is substantially less than the length of the strips. It additionally is preferable that the longer strip is positioned to trail the shorter loop during said movement. As shown and embodied in Fig. 5, the plurality of strips mounted adjacent to each other in an array extending generally in said direction include strips 42a, 42b and 42c which are mounted side by side in a horizontally extending array. The strips 42a, 42b and 42c are spaced from each other by support bars 40a and 40b which are about one to two inches wide. Strip 42b extends farther from wiper support 38a than strip 42a and is positioned to trail strip 42a in the movement indicated by arrow D. Similarly, strip 42c extends farther than strip 42b. This provides a preferred wiping action over the surface of the load. It is preferable that the apparatus include means for pivoting the wiper support solely about a single axis to wipe down the web with a wiper. As shown in Fig. 1, the means for pivoting the wiper support includes vertically extending axle 54 mounted on frame 34 and attached to arm 38 to allow arm 38 to pivot through the arc of arrow C. It is preferable that the apparatus includes means for moving the web and load generally in a straight line relative to the wiper support wipe down the web with the wiper. As shown and embodied in Fig. 1, the means for moving the web and load relative to the wiper support includes conveyor 22 which moves load 24 and the web wrapped on it generally in a straight line past wiper support bar 40. The apparatus preferably includes means for dispensing a web to be wrapped on a load, means for rotating the load relative to the dispenser means and means for moving the load wrapped with the web relative to the wiper support to wipe down the web with the wiper. As shown and embodied in Fig. 1, the means for dispensing the web includes a film web dispenser 32 having an arrangement for supporting and dispensing a film web 31. The means for rotating the load relative to the dispenser means includes turntable 30, which rotates load 24 about a vertical axis when load 24 is positioned on turntable 30 causing film web 31 to be wrapped on load 24. Alternatively, the means for rotating the load relative to the web dispenser may include an arrangement for revolving the web dispenser around the load in the manner shown in U.S. Patent Nos. 4,545,182 to McDowell, Jr. and assigned to Lantech, Inc. which is incorporated herein by reference. The means for moving the load relative to the wiper support includes conveyor 22 which moves load 24 past wiper support bar 40. According to the present invention, it is preferable that the apparatus include means for clamping and cutting the web of the wrapped load, and wherein the cutting means is mounted on the wiper support. As shown in Fig. 6B, the clamping means includes clamps 56, which are, in and of themselves, conventional clamps used in stretch wrapping machines such as those described in the patents incorporated by reference herein. The cutting means includes a blade or hot wire 58 mounted on support bar 40 which has a structure and operation which is conventional such as that shown in the patents incorporated by reference herein. rotating the load relative to a web dispenser to wrap the web on the load; clamping and cutting the web after the rotating step; and moving the wrapped load relative to a wiper support on which a strip wiper is mounted, to wipe down the web with the strip wiper. A sequence of operation is shown in Figs. 6A through 6D. In Fig. 6A, load 24 is positioned on turntable 30 (not shown in Fig. 6A, but shown in Fig. 1) and rotated by turntable 30 relative to film web dispenser 32 to wrap film 31 onto load 24. Alternatively, the step of rotating the load relative to the web dispenser may be accomplished by revolving the web dispenser around the load in the manner shown in U.S. Patent No. 4,545,182 to McDowell, Jr. and assigned to Lantech, Inc. which is incoporated herein by reference. Arm 38 is pivoted from the position shown in Fig. 6A to the position shown in Fig. 6B after load 24 stops rotating, and film web 31 is clamped with clamps 56 and cut as shown in Fig. 6C with cutters 58. An embodiment of the step of moving the wrapped load relative to a wiper support on which a strip wiper is mounted, to wipe down the web with a strip wiper, is shown by pivoting arm 38 about axle 54, which has a vertical orientation. The moving step can also or alternatively include moving load 24 past extended arm 38 as shown in the motion from Fig. 6C and to Fig. 6D. It is preferable that the moving step includes pivoting the wiper support solely about one axis. As shown and embodied in Figs. 6A and 6B, arm 38 is pivoted about axle 54 which is mounted along a vertical axis. By pivoting the wiper support solely about one axis, the present invention accomplishes, with less mechanical movement and attendant cost, the same function as was previously required by multiple articulation brush arrangements. It is possible to use a single articulation process because of the extended range of operation of the wiper according to the present invention. According to the present invention, it is preferable that the moving step includes conveying the load past the wiper support. As shown in Figs. 6C and 6D, load 24 is conveyed along conveyor 22 past wiper support arm 38. As a result, the load's movement off turntable 24 is used to complete the wipe down as the wiper maintains contact against the load. According to the present invention, it is preferable that the sequence of operation includes resetting the orientation of the wiper relative to the wiper support after the moving step. As shown in Fig. 6A, wiper strips 42 return from the position shown in Fig. 6D and are forced against rod 60 (also known in Fig. 1) to reorient wiper strips 42 to their original angle of extent from support bar 40. In addition to the sequence of operation shown and embodied in Figs 6A through 6D, other steps may be made, such as allowing arm 38 to pivot through a 180° sweep. In such an arrangement, the motion of the load exiting the turntable would not be needed to complete the wipe down as is required in the operation shown in Figs. 6A through 6D. Among the advantages of the present arrangement are its adaptability to normal stretch wrapping machines without substantial alteration. It lacks the fatigue in vertical bending which is present in conventional wipers. The strips conform to the shape of products, ensuring a wipe down along the whole width of the film tail. The arrangement can handle a considerable range of off-sets in load size, at least of 10" to 15". A 90° sweep of the wiper may be used to reduce the movement in the wrap cycle or a 180° sweep may be used to eliminate the need to have the motion of the load exiting the system to complete the wipe down. The strips afford adequate pressure on the tail of the film over an extensive range of product variation, particularly at the free end of the strip where the product is away from the cutter. In accordance with the present invention, there is provided an apparatus for wiping down a web wrapped on a load comprising: a wiper support; and a wiper including at least one strip doubled back along its length to form a loop, the loop being flexible in a direction generally parallel to a plan passing through the length of the strip, the wiper being secured to the wiper support and the loop extending from the wiper support for wiping down the web wrapped on the load by relative movement between the wiper support and the web in said direction. As embodied and shown in Fig. 7, the apparatus for wiping down a web wrapped on a load is integrated into a stretch wrapping machine 120. Stretch wrapping machine 120 includes a conveyor 122 for conveying a pallet load 124 along its length. Pallet load 124, before being wrapped, may consist of a plurality of individual sub-units 126 which are stacked on a skid 128 so that they can be unitized by a web of plastic film which is wrapped on pallet load 124 and skid 128 by the stretch wrapping machine 120. With reference to Fig. 7, pallet load 124 progresses along conveyor 122 in a generally left to right direction indicated by arrow A. Prior to achieving the position shown in Fig. 7, the stacked but unwrapped pallet load 124 stops on turntable 130, which is part of the conveyor 122. Turntable 130 rotates about a vertical axis to rotate pallet load 124 relative to a film web dispenser 132, which is mounted on a frame 134 proximate to conveyor 122. Film web dispenser 132 is suspended by a support 136 which is attached to frame 134 by a rack and pinion drive mechanism to drive film web dispenser 132 in the vertical direction of arrow B along frame 134. This allows pallet load 124 to be wrapped along its full height when the width of the film web 131 is less than the height of the pallet load 124. Film web dispenser 132 dispenses film web 131 in a conventional manner. According to the present invention, the apparatus includes a wiper support. As shown and embodied in Fig. 7, the wiper support includes a horizontally extending arm 138 and a vertical support bar 140 mounted across one end. The other end of arm 138 is mounted on frame 134 through the use of vertical axle 154, so that arm 138 pivots through an arc of arrow C about a vertical axis. A hydraulic control cyclinder 155 (partially obscured) also connects arm 138 and frame 134 and is used to position arm 138 during operation. According to the present invention, the apparatus also includes a wiper including at least one stip doubled back along its length to form a loop, the loop being flexible in a direction generally parallel to a plane passing through the length of the strip, the wiper being secured to the wiper support and the loop extending from the wiper support for wiping down the web wrapped on the load by relative movement between the wiper support and the web in said direction. As shown and embodied in Fig. 7, said at least one strip includes a plurality of strips 142 of ultra-high molecular weight plastic, such as those made by DuPont under the names Delron, Ertalon, and Ertalite. According to the present invention, it is preferable that the strip length is substantially greater than the strip width and the width is substantially greater than the strip thickness. As shown and embodied in Fig. 8, each strip 142 is about 30" long, 5" wide, and 1/16" thick and is doubled back along its length to form a loop. The length of the strip, and therefore the loop, is determined by the ranges of variation in product size. Each strip 142 has two end portions 144 and 146 along its width. It is preferable that the two end portions 144 and 146 are both secured to the bar 140 of the wiper support. Fasteners such as rivets 148 can be used for this purpose. Because of the dimensions and mounting of the strip, the loop extending from the wiper support is flexible in a direction generally parallel to a plane missing through the length of the strip, which in Figs. 7 and 8, would be a horizontally oriented plane. Similarly, because of the dimensions and mounting of the strip, the loop extending from the wiper support is rigid about an axis in the plane passing through the length of the strip. As shown in Figs. 7 and 8, the loop formed by strips 142 are rigid about an axis lying in a horizontally oriented plane. The loop is especially rigid about an axis perpendicular to the plane of the drawing in Fig. 8. A result, the loops 142 are extremely resistant to the effects of gravity and do not sag even after a prolonged period of operation. According to the present invention, it is preferable that said at least one strip includes a plurality of strips mounted adjacent to each other along the wiper support in an array extending generally perpendicular to said direction and are spaced apart from each other. As shown and embodied in Figs. 7 and 8, strips 142 are mounted adjacent to each other in an array extending along the vertical extent of support bar 140, and are spaced from each other so as to be independently movable, relative to each other, about a vertical axis. According to the present invention, it is preferable that said at least one strip includes a nested plurality of strips. As shown in Fig. 9, the nested plurality of strips includes outer strip 142 and inner strip 143 which run parallel to each other, form a loop, and have their ends attached to support bar 140. The use of a nested plurality of strips allows for greater pressure a tip 145 but does not restrict bending when the loop is bent at a tight radius. As a result, tip pressure is maintained when wiping down loads which are positioned far away from the web cutter as shown in Fig. 10A, as well as permitting bending at a tight radius for wider loads positioned closer to the support bar 140. The use of wiper strips according to the present invention allows a series of loads of varying sizes to be wiped down in a continuous operation without adjusting or varying the wipe down arrangement. The multiple number of strips along the length of the support bar 140 also allow for automatic adaptability to irregular shaped loads. According to the present invention, it is preferable that said at least one strip includes a plurality of strips mounted adjacent to each other in an array extending generally in said direction. It is preferable that the loop formed by at least one of said plurality of strips extends farther from the wiper support than the loop formed by at least another one of said plurality of strips. It also is preferable that the longer loop is positioned to trail the shorter loop during said movement. As shown and embodied in Fig. 13, the plurality of strips mounted adjacent to each other in an array extending generally in said direction include strips 142a and 142b which are mounted side by side in a horizontally extending array. The loop formed by strip 142b extends farther from wiper support 138a than the loop formed by strip 142a and is positioned to trail strip 142a in the movement indicated by arrow D. This provides a preferred wiping action over the surface of the load. According to the present invention, it is preferable that the two end portions of the loop are spaced from each other. As shown in Fig. 9, end portions 144 and 146 are spaced from each other by placing support bar 140 between them and by dimensioning bar 140 to be at least around 1" or 2" in width. This spacing of end portions 144 and 146 further improves the effective range of satisfactory bending characteristics of the loop of strip 142 with regard to loads that are spaced different relative distances from support bar 140 as shown in Figs. 10A and 10B. It also improves the rolling characteristic of the loop of strip 142 as discussed below in relation to Fig. 11. According to the present invention, it is preferable that the loop includes two spaced generally parallel portions which extend to a rounded outer portion. As shown and embodied in Fig. 9, generally parallel portions 150 and 152 extend from end portions 144 and 146 out to a rounded outer tip portion 145. These generally parallel portions 150 and 152 can be allowed to diverge substantially more than is shown so that tip 145 is larger and more gently rounded and still be within the scope of this limitation. According to the present invention, it is preferable that the generally parallel portions of the loop are spaced at a distance substantially less than the distance from the brush support to the outer tip portion. As shown and embodied in Fig. 9, the generally parallel portions 150 and 152 are spaced at a distance substantially less than the distance from support bar 140 to tip 145 in order to accommodate a wide range of load widths. According to the present invention, it is preferable that the apparatus include means for pivoting the wiper support solely about an axis generally perpendicular to a plane missing through the length of the strip to wipe down the web with a wiper. As shown in Fig. 7, the means for pivoting the wiper support includes vertically extending axle 154 mounted on frame 134 and attached to arm 138 to allow arm 138 to pivot through the arc of arrow C. According to the present invention, the apparatus includes means for moving the web and load generally in a straight line relative to the wiper support to wipe down the web with the wiper. As shown and embodied in Fig. 7, the means for moving the web and load relative to the wiper support includes conveyor 122 which moves load 124 and the web wrapped on it generally in a straight line past wiper support bar 140. According to the present invention, the apparatus preferably includes means for dispensing a web to be wrapped on a load, means for rotating the load relative to the dispenser means and means for moving the load wrapped with the web relative to the wiper support to wipe down the web with the wiper. As shown and embodied in Fig. 7, the means for dispensing the web includes a film web dispenser 132 having an arrangement for supporting and dispensing a film web 131. The means for rotating the load relative to the dispenser means includes turntable 130, which rotates load 124 about a vertical axis when load 124 is positioned on turntable 130 causing film web 131 to be wrapped on load 124. Alternatively, the means for rotating the load relative to the web dispenser may include an arrangement for revolving the web dispenser around the load in the manner shown in U.S. Patent No. 4,545,182 to McDowell, Jr. and assigned to Lantech, Inc. which is incorporated herein by reference. The means for moving the load relative to the wiper support includes conveyor 122 which moves load 124 past wiper support bar 40. According to the present invention, it is preferable that the apparatus include means for clamping and cutting the web of the wrapped load, and wherein the cutting means is mounted on the wiper support. As shown in Fig. 12B, the clamping means includes clamps 156, which are, in and of themselves, conventional clamps used in stretch wrapping machines such as those described in the patents incorporated by reference herein. The cutting means includes a blade or hot wire 158 mounted on support bar 140 which has a structure and operation which is conventional such as that shown in the patents incorporated by reference herein. A sequence of operation is shown in Figs. 12A through 12D. In Fig. 12A, load 124 is positioned on turntable 130 (not shown in Fig. 12A, but shown in Fig. 7) and rotated by turntable 130 relative to film web dispenser 132 to wrap film 131 onto load 124. Alternatively, the step of rotating the load relative to the web dispenser may be accomplished by revolving the web dispenser around the load in the manner shown in U.S. Patent No. 4,545,182 to McDowell, Jr. and assigned to Lantech, Inc. which is incorporated herein by reference. Arm 138 is pivoted from the position shown in Fig. 12A to the position shown in Fig. 12B after load 124 stops rotating, and film web 131 is clamped with clamps 156 and cut as shown in Fig. 12C with cutters 158. The step of moving the wrapped load relative to a wiper support on which a looped strip wiper is mounted, to wipe down the web with a looped strip wiper, is shown by pivoting arm 138 about axle 154, which has a vertical orientation. The moving step can also or alternatively include moving load 124 past extended arm 138 as shown in the motion from Fig. 12C and to Fig. 12D. According to the present invention, it is preferable that the moving step includes pivoting the wiper support solely about one axis. As shown and embodied in Figs. 12A and 12B, arm 138 is pivoted about axle 154 which is mounted along a vertical axis. By pivoting the wiper support solely about one axis, the present invention accomplishes, with less mechanical movement and attendant cost, the same function as was previously required by multiple articulation brush arrangements. It is possible to use a single articulation process because of the extended range of operation of the wiper according to the present invention. According to the present invention, it is preferable that the moving step includes conveying the load past the wiper support. As shown in Figs. 12C and 12D, load 124 is conveyed along conveyor 122 past wiper support arm 138. As a result, the load's movement off turntable 124 is used to complete the wipe down as the wiper maintains contact against the load. According to the present invention, it is preferable that the sequence of operation includes resetting the orientation of the wiper relative to the wiper support after the moving step. As shown in Fig. 12A, wiper strips 142 return from the position shown in Fig. 12D and are forced against rod 160 (also shown in Fig. 7) to reorient wiper strips 142 to their original angle of extent from support bar 140. According to one embodiment, it is preferable to maintain contact between the looped strip wiper and the web in fixed relation while moving the wiper support relative to the web to wipe down the web by rolling the looped strip wiper over the web. As shown and embodied in the sequence of operation of Figs. 11A and 11B, arm 138 is pivoted while maintaining non-sliding contact between looped strip 142 and the web and load which it contacts such that the loop rolls in non-sliding contact over the web and load when pivoted from the position shown in Fig. 11A to the position shown in Fig. 11B. In addition to the sequence of operation shown and embodied in Figs. 11A through 11B and Figs. 12A through 12D, other steps may be made, such as allowing arm 138 to pivot through a 180° sweep. In such an arrangement, the motion of the load exiting the turntable would not be needed to complete the wipe down as is required in the operation shown in Figs. 12A through 12D. Among the advantages of the present arrangement are its adaptability to normal stretch wrapping machines without substantial alteration. It lacks the fatigue in vertical bending which is present in conventional wipers. The loops conform to the shape of products, insuring a wipe down along the whole width of the film tail. The arrangement can handle a considerable range of off-sets in load size, at least of 10" to 15". A 90° sweep of the wiper may be used to reduce the movement in the wrap cycle or a 180° sweep may be used to eliminate the need to have the motion of the load exiting the system to complete the wipe down. The loop shape affords adequate pressure on the tail of the film over an extensive range of product variation, particularly at the tip of the loop where the product is away from the cutter.

Claims: Apparatus for wrapping a web (31; 131) on a load (24; 124) and wiping down the web (31;131) after it has been wrapped on the load (24;124) comprising: means (32;132) for dispensing a web (31;131) to be wrapped on a load (24;124); means (30;130) for rotating the load (24;124) relative to the dispenser means (32;132) to wrap the web (31;131) on the load (24;124); and a wiper support (40;40a, 40b;140;140a, 140b) having a wiper CHARACTERIZED IN THAT said wiper includes at least one strip (42;42a, 42b, 42c;142;142a, 142b;142, 143) having a length extending between two ends (44, 46;144, 146), a thickness and a width, the length and width substantially greater than the thickness, at least one end_(44;144, 146) secured to the wiper support (40;40a, 40b;140;140a, 140b), the strip (42, 42a, 42b, 42c;142;142a, 142b;142, 143) extending from the wiper support (40;40a, 40b;140;140a, 140b) along a length of the strip (42;42a, 42b, 42c;142;142a, 142b; 142, 143) and being flexible in a direction generally parallel to the thickness of the strip (42:42a, 42b, 42c; 142;142a, 142b;142, 143) for wiping down the web (31;131) wrapped on the load by a relative movement between the wiper support (40;40a, 40b;140;140a, 140b) and the web (31;131) in said direction. The apparatus of claim 1, wherein the strip (42;42a, 42b, 42c;142;142a, 142b;142, 143) is doubled back along its length to form a loop extending from the wiper support (40; 140), the loop being flexible in a direction generally parallel to its thickness. The apparatus of claim 1 or 2, wherein the strip (42;42a, 42b, 42c;142;142a, 142b;142, 143) is rigid about an axis extending in said direction. The apparatus of one of claims 1 to 3 wherein only one (44) of the two ends (44;46) of the strip (42) is secured to the wiper support (40) and the other end (46) is a cantilevered free end. The apparatus of one of claims 1 to 4, wherein the strip length is substantially greater than the strip width. The apparatus of one claims 2, 3 and 5, wherein the loop includes two end portions (144, 146) which both are secured to the wiper support (140). The apparatus of one of claims 1 to 6, wherein said at least one strip (42;42a, 42b, 42c;142;142a, 142b;142, 143) includes a plurality of strips (42;142;142, 143) mounted adjacent to each other along the wiper support (40; 140) in an array extending generally perpendicular to said direction. The apparatus of claim 7, wherein the plurality of strips (42;42a, 42b, 42c;142;142a, 142b;142, 143) are spaced apart from each other. The apparatus of one of claims 1 to 6 and 8 wherein said at least one strip (42;42a, 42b, 42c;142;142a, 142b;142, 143) includes a plulrality of strips (42a, 42b, 42c;142a, 142c) mounted adjacent to each another in an array extending generally in said direction. The apparatus of one of claims 1 to 9 wherein said at least one strip (42;42a, 42b, 42c;142;142a, 142b;142, 143) includes a nested plurality of strips (142, 143). The apparatus of one of claims 1 to 10, wherein at least one (42b, 42c;142b) of said plurality of strips (42;42a, 42b, 42c;142;142a, 142b;142, 143) extends farther from the wiper support 40a, 40b;140a, 140b) than at least another one (42a;142a) of said plurality of strips (42;42a, 42b, 42c;142;142a, 142b;142, 143) The apparatus of one of claims 2 to 11 wherein the loop formed by at least one (142b) of said plurality of strips (42;42a, 42b, 42c;142;142a, 142b;142, 143) extends farther from the wiper support (140a, 140b) than the loop formed by at least another one (142a) of said plurality of strips (42;42a, 42b, 42c;142;142a, 142b;142, 143). The apparatus of claim 11, wherein the longer strip (42c, 42b) is positioned to trail the shorter strip (42b, 42a) during said movement. The apparatus of claim 12 wherein the longer loop (142b) is positioned to trail the shorter loop (142a) during said movement. The apparatus of one of claims 1 to 14 wherein said two end positions (144, 146) are spaced from each other. The apparatus of one of claims 1 to 15, wherein said at least one strip (42;42a, 42b, 42c;142;142a, 142b;142, 143) is an ultra-high molecular weight plastic. The apparatus of one of claims 1 to 16 wherein said strips (42;42a, 42b, 42c;142;142a, 142b;142, 143) are spaced generally parallel to each other. The apparatus of one of claims 1 to 16 wherein said strips (42;42a, 42b, 42c;142;142a, 142b;142, 143) are spaced at a distance substantially less than the length of the strips. The apparatus of one of claims 2 to 18, wherein the loop (142; 142a, 142b) includes two spaced generally parallel portions (150, 152) which extend to a rounded outer tip portion (145). The apparatus of claim 19, wherein the generally parallel portions (150, 152) of the loop are spaced at a distance substantially less than the distance from the wiper support (140) to the outer tip portion (145). The apparatus of one of claims 1 to 20 including means (54;154) for pivoting the wiper support (40, 140) solely about a single axis to wipe down the web (31, 131) with the wiper. The apparatus of one of claims 1 to 21 including means (22;122) for moving the web (31;131) and load (24;124) generally in a straight line relative to the wiper support (40;140) to wipe down the web (31;131) with the wiper. The apparatus of one of claims 1 to 22 including means (56, 58;156, 158) for clamping and cutting the web (31;131) of the wrapped load (24;124). The apparatus of claim 23 wherein the cutting means (58;158) is mounted on the wiper support (40;140).

Inventors: STACKHOUSE, WILLIAM H.
Applicants: LANTECH, INC.
Application year: 1987
Main classification: B65B11
IPC codes: B65B11