US3441129A - Wrapper tightening - Google Patents

Description

April 29, 1969 J. H. JOHANSEN ETAL 3,

WRAPPER TIGHTENING Sheet Sriginal Filed July 7, 1965 INVENTORS. WALTER H. HERMAN JOHN H. JOHANSEN ATTORNEY.

WRAPPER TIGHTENING Sheet Q 2 of 2 Criginal Filed July 7,

INVENTORS WALTER H. HERMAN H. JOHANSEN JOHN ' ATTORNEY.

United States Patent ()flice 3,441,129 Patented Apr. 29, 1969 US. Cl. 206-65 2 Claims ABSTRACT OF THE DISCLOSURE A method and apparatus are disclosed for tightening the wrapper on a previously wrapped package being especially suited for the tightening of anoverwrap about geometrically shaped objects such as apair of cylindrical rolls of paper which are difiicult to initially wrap tautly. By the method and apparatus disclosed, gas heated to a suitable temperature is applied to the wrapped package in a manner such that it shrinks only-localized areas of the shrinkable wrapper on the ends of the package, such as spaced-apart and relatively narrow, elongated bands, so asto tighten substantially the entire overwrap upon the package. This insures that the wrapper on the sides of the; package will be free from distortion and wrinkles, thus presenting a neat appearance, and undistorted and clearly distinct art work on the overwrap. The disclosure is also directed to the package resulting from treatment by the method and apparatus of the invention.

This application is a division of our US. patent application,.Ser. No. 469,998, filed July 7, 1965, now patent No. 3,402,475, entitled Wrapper Tightening.

This invention relates to wrapping machines and to improvements therein and more particularly to a new and improved method and apparatus for tightening the wrapper on a previously wrapped package and to the improved product resulting from applying such method and apparatus.

In the past, various methods and apparatus havebeen employed to shrink a previously sealed wrapper about the contents of a package including, commonly, shrink tunnels of various designs. As a rule, such methods have included the step of heating the entire wrapped package by means of conventional shrink tunnels by conveying the wrapped package through a heating zone and thoroughly exposing it to heat .sufiicient to shrink the overwrap around the package. However, it has long been a problem with such operations to prevent distortion of art work previously placed upon the overwrap since all of the methods of applying heat to the overwrap have resulted in differential shrinking of the overwrap. Obviously, such distortion of the art work on the final package is disadvantageous and reduces the market value of the product.

The present invention provides a new and improved method and apparatus for shrinking the overwrap on a previously sealed package in order to tighten the overwrap around the contents therein. The method and apparatus of the invention are especially suited for the pur pose of tightening the overwrap around geometrically shaped objects such as a pair of cylindrical rolls of paper axially stacked adjacent to each other in the same plane. Many articles are commonly marketed in this fashion, that is, in packaged groups rather than as single items. The overwrap surrounding such groups of articles normally contains art work relating to the enclosed products as well as advertising or information about their source. It is especially important that such packages have a tight overwrap thus presenting a neat appearance and clearly distinct art work on the overwrap. It is well known to experts in the relatively intangible area of marketing that factors such as the overall appearance of the article and the neatness of art work on the overwrap are extremely important and influence to a high degree the success of selling such articles.

In accordance with the method of the invention, a package, comprising objects previously wrapped and sealed in a heat shrinkable wrapper, is moved relative to a heating zone so that its ends are presented to aligned streams of heated gas. The heated gas is applied in a manner such that it heat shrinks only localized areas of the ends of the package, such as two spaced apart and relatively narrow elongated bands, so as to tighten substantially the entire overwrap upon the package while leaving its sides free from distortion and wrinkles. The apparatus of the invention illustrates one type of apparatus for carrying out the method of the invention and comprises a hot gas source connected to at least one nozzle. Transfer means are arranged to move a package of objects, wrapped and sealed in a heat shrinkable overwrap, relative to said nozzle so that only its ends, or at least one end, are presented to the nozzle, which has at least one orifice from which heated gas from the hot gas source issues. The apparatus of the invention differs from the prior art in that it provides a means for selectively heat shrinking only localized portions of a package wrapper so as to leave the remainder undistorted and free from wrinkles while tightening the wrapper upon the entire package.

Therefore, it is an object of the invention to provide a method for tightening a heat shrinkable wrapper on a previously wrapped, sealed package.

An additional object of the invention is to provide a method for tightening a heat' shrinkable overwrap on a previously wrapped and sealed package containing one or more geometrically shaped objects, such as cylindrical rolls of paper without distorting art work on the longitudinal sides of the package.

An additional object of the invention is to provide apparatus for carrying out the method of the invention.

It is a still further object of the invention to provide an improved package having an overwrap tightened according to the invention.

These and additional objects and advantages of the invention will become apparent from the following detailed description of the invention made in conjunction with the following drawings in which:

FIGURE 1 is a front elevation view of apparatus of the invention, showing part in full and part in section,

FIGURE 2 is a sectional side view, taken along line 2--2 of FIGURE 1, showing details of a heating unit of the invention,

FIGURE 3 is a sectional plan view of apparatus of the invention, taken along line 33 of FIGURE .1, and

FIGURE 4 is a perspective view of a completed package having a wrapper tightened in accordance with the method of the invention.

Referring now to FIGURES 1, 2, and 3, which show a preferred embodiment of improved wrapper tightening apparatus of the present invention, a pair of cylindrical upright adjacently disposed rolls of paper 10 and 11, such as toilet tissue, are disposed upon and positioned in transverse alignment across a smooth platen 12 resting upon and supported by frame members 13 and 14. Laterally extending outwardly from each frame member 13 and 14 are respective hood portions 15 and 16 having, at their outer ends, respective upwardly depending portions 17 and 18 which have, at their upper ends, respective inwardly depending portions 19 and 20. Each respective inwardly depending portion 19 and 20 has attached thereto further respective inwardly and upwardly directed hood members 21 and 22 which cooperate with each other to support at their inner ends a transfer assembly, indicated generally as 23.

Transfer assembly 23 comprises a plurality of pusher elements 25 which are arranged in a flight chain in a manner which allows the lower elements 25a to travel in one direction and the upper elements 25b to travel in the return direction. The pusher elements 25 are drawn by roller chains 26, links of which are pivotably attached to a pusher element 25 within the gap between the bifurcated foot or base portion 27 of each pusher element 25. The lower pusher elements 25a are guided by means of the elongated channel 28 and the upper elements 25b ride upon guide members 29. The flight chain type transfer assembly 23 is driven by a pair of motor driven sprockets (not shown) in a manner well understood by one skilled in the art. The member 30 serves to close off the top of an elongated channel or cavity 32 which has two open ends and serves to close off the top of an elongated channel or cavity 32 which has two open ends and serves partially enclosed chamber for the heat shrinking operation of the invention.

A pair of spaced apart and parallel hot gas sources or nozzles 33 and 34 are disposed along each side of platen 12 and closely adjacent to upwardly depending portions 17 and 18.

Nozzles 33 and .3-4 are employed to direct the flow of hot gas toward the desired localized areas of the package which areas are to be heat shunk. They differ substantially from previously employed apparatus in that they do not merely supply heat to a shrink chamber but are arranged to apply heat to a particular localized area or to areas of a package and in a preferred manner as described below. Each of nozzles 33 and 34, comprises two spaced apart and substantially horizontal and parallel hollow members 35 and 36 having closed ends and the cavities of which are interlinked by a vertical, hollow member 37, each respective end of which passes through the wall of and joins with one of the hollow members 35 and 36 at a point equidistant from each of their ends. As shown in FIGURES 2 and 3, each horizontal member 35 and 36 of each of nozzles 33 and 34 has a plurality of longitudinally disposed and spaced apart holes 38 which serve to direct the flow of hot air or other gas toward preselected transverse areas on the ends of a previously wrapped package of articles, such as the rolls of paper 10 and 11, shown in FIGURES l and 3.

Nozzles 33 and 34 are recessed partially into shields 39 which may be constructed of asbestos or a type of refractory material capable of withstanding the elevated temperatures of said hot air or gas. Further hollow cylindrical members 40 and 41 pass through a respective upwardly depending portion 17 and 18 on each side of platen 13 and one end of each passes through the wall of and connects with, each respective hollow member 37 at a point equidistant between its ends. The opposite ends of members 40 and 41 connect with a heat source 42 through a common feed pipe 43 by means of a separate lateral feed pipes 44 and 45. In this manner, the cavities defined by members 35 and 36 connect with the cavity defined by members 37 and similarly these cavities connect the cavities defined by members 40 and 41 and hence, all connect to heat source 42.

Heat source 42 may be any type of heat source providing some means of controlling the temperature and, preferably, the velocity of the heated gas produced and propelled through heat pipes 44 and 45, of nozzles 33 and 34. As shown in FIGURE 1, a type of resistance heater is employed wherein an electrical resistance 48 is attached between two terminals 49 and 50, across which is placed an electrical potential, as is well understood in the art, thereby causing current to flow through electrical resistance 48 to create heat. Located adjacent resistance 48 and opposite feed pipe 43 is a blower unit '52 which is employed to accelerate the flow of air or other gas past heated resistance 48, which gas is then directed toward through flow pipe 43 and through holes 38 in each nozzle 33 and 34.

In normal operation, the pair of adjacent and upright rolls of paper 10 and 11, disposed upon and arranged transversely acros platen 12, are pushed slidably along platen 12 in a direction parallel to the longitudinal axis of platen 12 by the lower pusher elements 25a, pairs of which serve to push each respective package of two rolls in spaced apart relation along platen 12 relative to successive packages. As the packages are pushed through the relatively enclosed hood-like chamber 32 defined by platen 12, laterally and outwardly extending portions 15 and 16, upwardly depending portions 17 and 18, inwardly depending portions 19 and 20, and upwardly and inwardly portions 21 and'22, the ends of each package, containing generally a plurality of layers of heat shrinkable wrapper material in the area of the fold, a portion of which area has been previously heat sealed, pass closely adjacent to holes 38 through which the hot air or gas passes.

However, due, in part, to the particular design of the nozzles 33 and 34 and to the configuration and shape of holes 38, only preselected and limited areas of the wrapper are selectively heat shrunk during this passage through the above-described chamber 32. It has been found that when previously wrapped packages of articles are heat shrunk in the above described manner, the wrapper on the package, which often contains art work and printing on the elongate sides thereof, is measurably tightened upon the entire package. This is even more surprising when it is considered that only relatively small selected areas are heat shrunk as described above. Particularly significant is the fact that the art work and printing on the elongate sides of such a package are undistorted since the majority of heat shrinking occurs only in the selected portions on the ends of the package and generally only where a plurality of layers of the heat shrinkable wrapping material are present.

The particular areas of the package which have been preferably selected for heat shrinking the wrapper on a package as described above in the manner of the invention are those areas designated generally as 54 on the ends of the package shown in FIGURE 4. On a'package such as that shown in FIGURE 4, these areas 54 preferably are two relatively narrow parallel bands spaced apart and located generally within the top and bottom areas of each end of the package. These areas where the package wrapper is most loose draw-up when heat shrunk and tighten the longitudinal side panels and edges.

Thus, it can be seen that the wrapper is first folded around the pair on rolls in a direction parallel to a line perpendicular to their cylindrical overlapped marginally axes, and sealed along a parallel to said fold direction. Then the wrapper is overlapped and sealed marginally on the ends of each roll and flush with the surface of a re spective roll. This leaves two cars designated generally in FIGURE 4 as 55 which comprises a plurality of layers of wrapping material and which are folded down and heat sealed on each end. This inherently results in two relatively loose rolled edges at the top and bottom of each end of the package as shown in FIGURE 4.

When subsequently heat shrunk in the parallel band areas 54 however, it has been found that the entire' wrapper on the package is measurably tightened so that the rolls 10 and 11 are snugly held together. The appearance of the package is greatly enhanced since such tightening removes the loose appearance and wrinkles from the wrapper and draws all four elongate side panels taut without deforming them or distorting the art work and printing on the sides thereof, such as by differential stretching or shrinking.

For example, a package was formed by wrapping a pair of rolls of toilet tissue, vertically upstanding adjacent each other in the same plane, with a standard cast polyethylene film about .001 inch and having a single direction orientation running lengthwise along the package. This package was heat sealed on the ends and then treated with the process and apparatus of the present invention. It was found that the gap between the rolls was reduced by as much as inch due to tightening of the wrapper in the areas designated as 54. Even more striking results can be obtained by the use of more expensive biaxially oriented shrinkable polyethylene film.

The temperature of the hot gas exiting from holes 38 in nozzles 33 and 34 is preferably from about 200 F. to about 450 F. for heat shrinkable polyethylene material and the end portions are spaced from nozzles 33 and 34 by a distance of from about A; to 1 inch. Typically, pusher element speeds might be from about 30 to 100 feet per minute. The capacity of the heat source will, of course, be variable. However, a typical heater employed had a capacity such that it heated 24 cubic feet per minute of room air to between 400 and 500 F. at the heater. It will be apparent to one skilled in the art that the above figures may be different depending upon the type of material employed and the speed at which the packages are conveyed through apparatus of the invention.

Although the examples described above relates to rolls of paper, it will be apparent that similar advantages may be obtained with objects of other shapes. Thus, the invention might be used to tighten the wrapper on a previously wrapped and scaled loaf of bread. Also, more than two objects might be packaged and treated according to the invention.

The pusher elements 25 and platen 12 might be replaced by a standard conveying system or other transfer means without losing the advantages of the invention. It will also be apparent that the enclosing hood portions might be removed, but in that instance, it may be necessary to employ gas at a higher temperature or to reduce the distance between the ends of the package and the nozzles since such a hood portion serves to hold the hot gas previously expended in an area locally adjacent the ends of the package for a longer period of time.

The heating elements or nozzles 33 and 34 might have a substantially different configuration in order to impress a more desirable heat shrinking pattern on a different type of package. Also, the number of orifices 38 might vary, and in some cases, it might be preferable to have a continuous slit orifice instead of a plurality of substantially aligned orifices where the heat shrinkable overwrap employed would withstand a relatively constant application of heat. The method of the invention might also be applied to only one end of such a package, and the nature of the articles as well as the heat shrinkable material might be such that this would provide sufiicient shrinkage to tighten satisfactorily the Wrapper on the package.

From the above, it can be seen that the invention provides a new and improved method of tightening a heat shrinkable wrapper on a. package without distorting the art work on side portions thereof which comprises locally applying heated gas to preselected areas on the ends of the package to shrink only those preselected areas and thereby tighten the wrapper on the entire package. Accordingly, the invention also provides a novel apparatus capable of performing the method of the invention which apparatus includes a hot gas source, at least one nozzle, said nozzle comprising at least one hollow elongated member having one or more orifices along its length, and transfer means to move a package, having a heat shrinkable overwrap in enclosing relationship thereon, relative to saidhot gas nozzle and in a direction substantially parallel to said elongated member, said package being oriented such that at least one end is presented to said orifice. Furthermore, the invention provides a novel type of merchantable package having a plurality of articles tightly enclosed by heat shrinkable overwrap, only portions of which have been selectively heat shrunk in order to assure that the remaining portions will be free from wrinkles and undistorted by differential heat shrinking or other cause.

It will be apparent that numerous changes and modifications can be made without departing from the scope of the invention. Therefore, the invention is not intended to be limited to the particular embodiments shown or described.

What is claimed is:

1. In combination, a plurality of objects disposed upright and adjacent each other so as to substantially contact each other on adjacent side faces, and an overwrap consisting of a thin sheet of heat shrinkable material, said overwrap surrounding said objects and having overlapping marginal areas heat sealed together on the ends and longitudinally along a line between the plurality of objects to form a package, only the ends of said package and at least one end, having at least two localized spaced apart and substantially parallel, relatively narrow, elongated areas of heat shrinking, substantially said entire overwrap tightly engaging said plurality of objects and having longitudinal side faces free from distortion and wrinkles.

2. A merchantable package comprising a plurality of objects disposed upright and adjacent each other so as to substantially contact each other on adjacent side faces, said objects being surrounded by an overwrap of heat shrinkable sheet material having overlapping side and end edges heat sealed together, said package having decorated side panels free from other seams or distortions, and multilayered portions of said end panels resulting from said heat sealing of overlapping end edges, said multilayered portions having at least two localized spaced apart and substantially parallel, relatively narrow, elongated areas which have been heat shrunk, said entire overwrap tightly engaging said plurality of objects.

References Cited UNITED STATES PATENTS 2,835,433 5/1958 Swartz et a1. 229--62 2,987,402 6/ 1961 Dold 229-87 2,994,466 8/1961 Thompson. 3,381,817 5/1968 Harm 206-65 WILLIAM T. DIXSON, JR., Primary Examiner.

US. Cl. X.R.

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