US3329262A - Elastic protective corner and tensioning strips for transportable brick packages - Google Patents

Description

July 4, 1967 H. T. MARTIN ETAL ELASTIC PROTECT STRIPS FOR IRA IVE CORNER AND TENSIONING NSPORTABLE BRICK PACKAGES Filed Oct. 18, 1965 lNl/E/V TORS Ho/l/ns/vead 7 Martin Russe/ALGou/d July 4, 1 H. T. MARTIN ETAL ELASTIC PROTECT IVE CORNER AND TENSIONING NSPORTABLE BRICK PACKAGES STRIPS FOR TRA 2 Sheets-Sheet 2 Filed Oct. 18, 1965 INVENTORS Hal/inshead 7." Mari/ n Russel/JGou/a' United States Patent FOR TRANSPORTABLE BRICK PACKAGES Hollinshead T. Martin, Evanston, and Russell J. Gould,

Arlington Heights, 11]., assignors to Signode Corporation, Chicago, Ill., a corporation of Delaware Filed Oct. 18, 1965, Ser. No. 497,050 4 Claims. (Cl. 206-65) The present invention relates to a brick package and has particular reference to a novel transportable banded stack of bricks which, after it has been assembled, is more stable under conditions of handling, transportation and storage, both at the kiln and in the field, than has heretofore been possible in connection with similar brick packages designed for the same purpose.

In recent years a major step toward the efficient and economical handling of bricks has been the development of a brick package consisting of a number of individual pack units, each of which is encircled by a single peripheral loop of metal strapping, with the various pack units being maintained in longitudinal alignment and contiguity by longitudinally extending corner strips at the four corners of the package straps are positioned. At one or two locations in the pack, openings for the forks of a lift truck are provided by omitting a few longitudinally aligned bricks and, additionally, before the metal straps are applied, elongated paper, cardboard or wooden corner protectors are folded around the four longitudinally extending corners of the package to provide L-shape corner strips and these strips are subsequently confined in place by application of the metal straps. These corner protectors or strips are intended to prevent the metal straps form cutting into the adjacent corners of the bricks and they also serve the purpose of tying the various pack units together in substantial cont-iguity against longitudinal separation. It is to this general type of brick package that the present invention pertains.

Although a brick package of the general type briefly outlined above has materially reduced the cost of brick handling, it has not proved altogether satisfactory from the standpoint of package stability. Where the corner strips are formed of paper or carboard, very little, if any, tension can be applied to the strips during their application and, as a consequence, the unit packs are only loosely maintained in their contiguous relationship. Although the bricks which comprise any given unit pack may be tightly banded together, the unit packs which are not tightly held together tend to separate under the slightest provocation, as for example under the joggling influence of the box car, truck or other transportation medium. This is due to the relatively low elongation factor of ordinary paper or cardboard. Seperation of the unit packs in the upper regions thereof is particularly prevalent when conditions of unstable equilibrium arise, as for exemple when a given br-ick package is placed upon uneven terrain such as may exist in the field near a particular scene of brick installation. Placement of such a brick package on a foreign object such as a stone or an extraneous brick fragment may cause such unit pack instability as to rupture one or both of the upper corner strips in one or more places and effect partial collapse of the package. An additional limitation that is attendant upon the use of paper or cardboard as a corner strip resides in the inability of such materials to withstand weathering. For this reason, contractors frequently provide complete coverage for brick packages which must be left in the open during inclement weather and they avoid brick erecting operations during such weather.

about which the various metal- 3,329,262 Patented July 4, 1967 An equally serious limitation that is attendant upon the use of paper or cardboard as a corner protector resides in the crushability of these materials, the corners which they are designed to protect readily cutting through the same when the relatively high binding tension of the metal strap requisite to proper binding is applied, or when it is exceeded by unbalanced forces which arise during handling of the package. When this occurs, not only is there likelihood of rupturing the relatively fragile corners but there is the distinct danger of such corners, When sharp, cutting through the strap and rupturing the latter, thus releasing all of the bricks in the particular unit pack which the strap surrounds.

Wooden corner strips are seldom used because they are costly, difficult to fashion and apply, and they are not readily susceptible to progressive unit pack separation. Furthermore, if they are to be effective as a corner protector they must be of appreciable thickness and in such an instance the intervening metal binding strapping material between adjacent corner protectors is maintained spaced from the sides of the package with a consequent loss of centripetal binding force on the adjacent bricks.

Due to the above outlined limitations associated with cardboard, paper and wooden corner protectors, considerable attention has recently been given to the possible use of various flexible plastic materials which not only are moisture proof but which possess a suflicient degree of elasticity that they may be applied and held in position under tension so that there will be an appreciable degree of residual tension in each span between adjacent metal binding straps tending to draw the associated adjacent brick packs hard against each other, thus obviating the tendency for separation of the packs, especially in the uppper regions thereof, when longitudinal separation forces are applied thereto as heretofore described. As a result of extensive experimentation with a wide variety of known plastic materials, no specific material in its raw or unworked condition has been found which is suitable for use in the manner outlined above as a combined-corner protector and tensioning strip for the unit packs of a brick package. Efforts have therefore turned to the mechanical and physical working of various plastic materials to impart to them the required physical properties whereby they may effectively serve their required protective and tensioning functions. Among the most likely materials for such experimentation have been those which are capable of grain orientation such as nylon, polyethylene, polypropylene and polypropylene copolymer, particularly the latter.

Heretofore the results of extensive experimentation with polypropylene for corner strip use have not proved altogether satisfactory. Stretching of rolled sheets of polypropylene has established a molecular grain-orientation of the material and improved the tensile strength thereof, thus greatly reducing the tendency of such material, when used as a corner strip, to creep or elongate in time, but the stretched material exhibits the disadvantage that it is unidirectionally brittle and is not readily bendable in the longitudinal direction of stretching without splitting into ribbons so that it is difficult, if not impossible, of continuous application to the stacked bricks of a package by passing the same through a folding die. Such portions of a ribbon as may withstand the folding operation, when applied as a corner strip, are readily susceptible to splitting under the binding force of the metal strapping material and the cutting action of the brick corners.

An additional and serious limitation that is attendant upon the use of such grain-oriented polypropylene material as a corner strip resides in the extreme susceptibility of the material to unidirectional with-the-grain scufiing when frictional abrasive forces in the longitudinal direction of the strip are encountered. Thus, during pulling of the strip through the narrow folding die surface-fuzzing of the material frequently has clogged the folding die aperture and resulted in ultimate rupture of the strip. Still further, during transportation of the brick package, the repeated shifting of the load on the box car or truck platform has produced a progressive condition of scuffing resulting in strip rupture.

Rolling of a polypropylene sheet has overcome such unidirectional brittleness but only at the expense of lack of tensile strength and, furthermore, the rolled material, having incomplete grain orientation will elongate in time. Thus, a brick package which apparently is tight at the time of its initial assembly, may assume a condition of looseness by the time it is put to use in the field.

The present invention is designed to overcome the above-noted limitations that are attendant upon the construction and use of both conventional and experimental brick packages and, toward this end it contemplates the provision of a brick package which employs as a corner strip a specially treated polypropylene corner strip of conventional L-shape cross section and which may be applied by conventional corner strip-applying apparatus and methods yet which, when in position in the package, possesses all of the physical attributes necessary for its proper functioning both as a corner protector and as a tensioning member, including the possession of adequate tensile strength so that it may elongate within its elastic limit during application to the package, resistance to creeping after application to the package so that it will permanently maintain the necessary package stability, and ability to pass through a folding die without splitting or scuffing. The specific treatment of the raw polypropylene sheet material by means of which the corner strip of the present invention is produced forms no part of the present invention and it is deemed sufficient to state that by a particular process involving the simultaneous stretching and rolling of the sheet material, followed by a surface searing operation, a strip is produced which may be described as having an over-all grain orientation which extends largely, but not completely in a longitudinal direction and has a small amount of transverse grain orientation, together with thin skin or surface random grain orientation on opposite sides thereof. It has been found that whereas a completely grain oriented strip of polypropylene is extremely susceptible to splitting upon bending in one direction as previously described, a very small percentage of transverse grain orientation will effect the necessary molecular adhesion for bending of the strip in any direction. It also has been found that for effective resistance to scufiing in all directions a substantial random grain orientation is required at the surface of the strip. Stated otherwise, the corner strip employed in connection with the present brick package may be said to possess substantial but incomplete sub-surface grain orientation with complete or random surface orientation, i.e. surface deorientation.

The provision of a brick package such as has been set forth above constitutes the principal object of the present invention. Other objects and advantages of the invention, not at this time enumerated, will readily suggest themselves as the nature of the invention is better understood.

In the accompanying two sheets of drawings forming a part of this specification, one illustrative embodiment,

of the invention has been shown.

In these drawings:

FIG. 1 is a perspective view of a unit pack of bricks, showing the same severed from a larger brick package which has been assembled, banded, and longitudinally tensioned by means of elongated plastic corner strips in accordance with the principles of the present invention;

FIG. 2 is a perspective view of a brick package which is comprised of a number of the unit packs of FIG. 1;

FIG. 3 is an enlarged fragmentary view of one of th terminal corners of the brick package of FIG. 2',

FIG. 4 is a fragmentary perspective view illustrating a preferred manner of progressively applying the corner strips to the package during assembly of the latter;

FIG. 5 is a front elevational view of a folding die employed in connection with application of the corner strip and illustrating schematically the complete folding of the corner strip material during passage through the die;

FIG. 6 is a fragmentary perspective view of a length of plastic tape which, when creased to right-angle cross section, is suitable for use as a corner strip in accordance with the present invention;

FIG. 7 is a greatly enlarged longitudinal sectional view taken on the line 77 of FIG. 6 and illustrating schematically the molecular structure of the plastic tape of FIG. 6;

FIG. 8 is a transverse sectional view taken on the line 88 of FIG. 6, the view being similarly illustrative of the molecular structure; and

FIG. 9 is a fragmentary side elevational view, schematic in its representation, illustrating the compressional forces which are exerted upon adjacent brick packs under the influence of the elastic corner strips of the present invention.

Referring now to the drawings in detail and in particular to FIGS. 1 to 3 inclusive, a typical brick package embodying the principles of the present invention has been disclosed in FIG. 2 and designated in its entirety at 10. The package is comprised of a plurality of individual self-sustaining unit packs 12, one of which is shown in FIG. 1. The package 10 does not deviate appreciably in outward appearance from a conventional brick package and, in the exemplary form which has been selected for illustration herein, the arrangement is generally cubic and consists of four of the unit packs 12 arranged in contiguous face-to-face longitudinal alignment. Each unit pack is banded by a metal steel strap 14 and the various unit packs are held together against longitudinal separation in a manner that will be described in greater detail presently by longitudinally extending corner protectors or strips 16 which are L-shape in transverse cross section and underlie the various straps 14. As is customary in connection with similar brick packages, at selected regions of the package 10 longitudinal rows of bricks are omitted in stacking the bricks, thus defining openings 18 which preferably extend completely through the package and which are designed to receive the tines of a fork lift truck by means of which the package as a whole may be transported.

The specific dimensions of the individual bricks and their stacked disposition may be varied but for exemplary purposes herein each unit pack 12 may be considered to be comprised of standard American bricks 20 supported on their stretcher sides with the corresponding bricks of adjacent packs being disposed in end-to-end contiguity. With such bricks, a stacked arrangement results which is thirteen bricks wide, eight bricks high and four bricks deep, i.e. in the longitudinal direction of the package.

Although as previously stated, the brick package 10 is conventional in outward appearance, the inventive corner strips 16 of the present invention, when applied in a particular manner, provide a package which is appreciably more stable than are conventional packages of a similar nature but which employ corner strips of cardboard, paper or wood. In developing the corner strip 16, it has been necessary not only to bear in mind the physical attributes required to produce a satisfactory package, but also such additional attributes as are required for commercial application of the corner strip to the brick stack to produce the package. Among the former attributes are a proper combination of tensile strength, elasticity and creep resistance (i.e. resistance to elongation over a period of time) so that the various unit packs will be drawn hard against one another when the strip is applied .5 under tension and maintained in contiguity throughout the useful life of the package; resistance to shearing under the cutting influence of the sharp brick edges; ability to cushion the brick edges against the binding force of the metal straps so that they will not chip or crumble when the straps are applied; and resistance to external abrasive forces such as may take place during transportation and handling of the packages. Among the latter attributes are ability to fold without longitudinal splitting when a flat strip of the material is progressively passed through a folding die preparatory to shaping the same to angular corner strip configuration; and resistance to scufiing so that the strip will not shred in the surface regions thereof when passing through the die and thus cause clogging of the die and ultimate rupture of the strip in the die aperture. All of these physical properties are necessary to the production of a successful brick package inasmuch as a brick package which is entirely satisfactory in service is commercially unacceptable if it cannot be produced economically. Therefore, for a clear understanding of the problems involved in the production of the inventive corner strip of the present invention, a preferred method of progressive application of the corner strips 12 to a continuous brick stack has been schematically illustrated in FIG. 4.

Briefly, the stacked bricks 20 are intermittently advanced on a live conveyor assembly 30 (FIG. 4) through a corner strip applying station S1, a sealing station S2 and a strapping station S3 progressively and in the order named. At the station S1, the plastic corner strip material is fed from a dispenser 36 in the form of a flat ribbon or tape 38 and is passed between a pair of drag rollers 40 from whence it passes around guide rollers 42 and enters a folding die 44 (see also FIG. Where a longitudinal crease 46 is imparted thereto by forcibly bending the material fiat against itself so that the elastic limit of the material is exceeded at the region of torsional application. Thus, as the material emerges from the folding die, its restorative properties cause it to assume the desired right angle configuration as indicated at 48 for proper and facile application to the continuously moving brick stack. At its region of application, a spring pressed finger 50 of conformable right angle configuration presses the continuous angular ribbon of material into position along the adjacent corner edge of the stacked bricks.

For each corner strip application there will be a separate dispenser 36, together with its associated strip-applying mechanism. Only one such dispenser has been shown on the far side of the conveyor 30 in FIG. 4 for applying a corner strip to one upper longitudinal edge of the stack but it will be understood that a similar dispensing arrangement will be provided on the near side of the conveyor 30 for application of a strip to the other upper longitudinal edge. Similarly, if corner strips are to be applied to the lower longitudinal edges of the stack, additional lower dispensing mechanism will be provided.

Still referring to FIG. 4, the angular strip material 48 is applied to the stack under appreciable longitudinal tension and this is accomplished by periodically indexing the conveyor to bring one of the unit packs 12 into transverse register with a strap feeding chute 52 associated with a conventional strap feeding mechanism 54 at the strap feeding station S2. A length of steel strapping 55 is caused to encircle the unit pack 12 and, at the strapping station S3, a strapping machine 56 serves to apply a seal 58 to the overlapping ends of the encircling loop of strapping, and to sever the thus applied strap 14 from the source of strapping, all in the manner of conventional strapping machine operation. The strap 14, in thus binding the bricks of the unit pack 12 together, also captures the various lengths of corner strip material 48 which have been applied to the stack and, then, during the next succeeding indexing of the conveyor 30, this material is pulled forwardly and placed under tension under the retarding influence of the drag rollers 40. The operation is repetitive scufiing. Without such and, during the next strapping operation a steel strap 14 is applied to the next adjacent unit pack 12. Due to the retarding influence of the drag rollers 40), the intervening corner strip material 48 between the two adjacent straps 14 will have been appreciably elongated so that the tension developed therein will operate to draw the two adjacent unit packs 12 hard against each other as illustrated by the arrows in FIG. 9.

The thus banded unit packs 12, securely bound to one another by reason of the tension in the corner strip material 48, are periodically advanced on the conveyor and at a suitable severing station along the conveyor they may be separated into individual packages of four unit packs each or any other desirable unit pack multiple. Due to the thermoplastic nature of the corner strip material 48, severing of the packages from the stack may be accomplished by the use of a suitable Calrod type burning tool. Upon severing of the strips 48 a completed package including the coextensive corner strips 16 results.

Considering now the physical properties of the plastic material employed in the production of the corner strips 16, it has been found that a sheet of polypropylene copolymer when subjected to a simultaneous stretching and rolling operation, followed by a surface searing operation, will produce a sheet of material which, when divided into ribbons of a suitable width for corner strip application, possesses physical properties of an unusual nature enabling the same to be applied in the manner previously indicated to a brick stack whereas, hitherto, successful application of numerous other plastic ribbons has not been attained despite much experimentation. A fragment of such a ribbon has been illustrated in FIGS. 6, 7 and 8 and it may be regarded as being a short length of the ribbon 38 associated with the dispenser 36 of FIG. 4. The dimensions of the ribbon 38 are not critical within reasonable limits but it has been found that a ribbon which is one inch in width and which has a thickness of 0.02 inch is entirely suitable for corner strip construction.

As shown in FIGS. 7 and 8, the aforementioned simultaneous rolling and stretching operation which is performed upon the raw polypropylene copolymer imparts to it a molecular orientation 60 which is largely but not entirely unidirectional in the direction of stretching. Because the ribbon has such predominant longitudinal orientation, its tensile strength is greatly increased and its tendency to creep, i.e. to elongate after a period of time when under tension, is materially reduced. A slight amount of cross-orientation 62 is allowed to remain in the ribbon and this is sufficient to permit complete folding of the ribbon when it passes through the folding die 44 of FIG. 5. Unoriented polypropylene is, of course, amenable to folding in any direction but it lacks tensile strength and it is highly susceptible to creeping. It has been found however that a very slight amount of cross-orientation in the material will'sufifice to allow longitudinal folding of the ribbon.

In the treatment of the polypropylene material, after such predominant longitudinal molecular orientation has been imparted to it, the opposite surface regions of the material are caused to become completely deoriented as indicated at 64 and this may be effected by a surface searing operation, utilizing a flame or searing rolls. Molecularly oriented polypropylene is highly susceptible to unidirectional surface abrasion or scufiing in the direction of orientation although it is almost entirely resistant to such scufling in a transverse direction. The slight amount of cross orientation indicated at 62 has a negligible effect as a deterrent to scufiing and, for resistance to scufling in all directions, a completely deoriented material is required. The random surface orientation indicated at 64 thus affords this resistance to deorientation of the ribbon at its surface regions, the friction which is developed as the ribbon passes through the folding die 44- will create a condition of surface fuzzing which rapidly clogs the die aperture and leads to ultimate rupture of the ribbon. Additionally, when the brick package is in the process of being transported in a truck or flat-car, the joggling action which is encountered incident to a rough terrain or due to acceleration and deceleration of the vehicle will permit limited shifting of the package without any deleterious scufiing action. The random surface orientation indicated at 64 offers additional advantages which render the ribbon suitable as a corner strip material. One such advantage is that it augments the action of the aforementioned cross-orientation in inhibiting splitting of the material when it is folded longitudinally. When any material becomes split due to a folding or bending action, the critical region is at the apex of the bend. Thus, with a completely deoriented surface region available at the apex of the fold when the material is passing through the folding die 44, this critical region is reinforced and the initial microscopic crevice which initiates the splitting of most solid materials does not take place. A third advantage oifered by complete surface deorientation of the ribbon resides in an appreciable increase in the slip-efficiency of the ribbon. This slip-eificiency is related to the aforementioned resistance to scufiing but it also presents the further and distinct advantage that the coefficient of friction between the metal binding strap and the plastic material of the corner strips 16 is appreciably reduced so that the strap, during tensioning thereof, will slide around the various corners afforded by these strips and distribute its tensioning effect more uniformly around the periphery of the package.

It will be appreciated that brick arrangements other than the specific arrangement herein illustrated are capable of being packaged according to the present invention. For example, although the bricks in each unit pack 12 are arranged in side-by-side relationship while the bricks in adjacent unit packs are disposed in end-toend relationship, a reverse arrangement of bricks may be resorted to in which the unit packs are banded by steel straps which pass over the ends of the individual bricks and in which the corner strips 16 overlie such ends. Therefore in the appended claims the term end-toend is to be broadly constructed as relating to the faces of the bricks which meet in contiguity and extend transversely of the brick stack on the conveyor. Similarly, the term side-by-side is to be broadly construed as relating to the faces of the bricks which meet in contiguity and extend longitudinally of the stack. The invention is therefore not to be limited to the exact arrange ment of parts shown in the accompanying drawings or described in this specification as various changes in the details of construction may be resorted to without departing from the spirit of the invention. Modifications may thus be resorted to within the scope of the accompanying claims.

Having thus described our invention, What We claim and desire to secure by Letters Patent is:

1. A packaging component for rectangular brick packages of the type consisting of separable brick packs disposed in side-by-side contiguity, each pack being banded by a steel strap, said packaging component comprising: an elongated moisture-impervious abrasion-resistant corner protector and tensioning strip assuming an L-shape cross section and adapted to overlie one longitudinal corner edge of the package and to extend under tension between and beneath adjacent steel straps, said strip being formed of a molecularly orienta-ble heat-fusible thermoplastic polymer having the inner portion thereof set with a molecular orientation which is largely longitudinal but which presents sufficient transverse molecular orientation to enable the strip to be folded longitudinally without spliting, and having sufficient re sistance to elongation-in-time that it will not stretch under such separation forces as may be encountered by adjacent bricks when the package is handled, and having outer surface portions which are fused to a depth of between one and three mils so as to impart abrasion resistance to the strip as a whole.

2. A packaging component as set forth in claim 1, wherein said molecularly orientable thermoplastic polymer is polypropylene.

3. A packaging component as set forth in claim 1, wherein said molecularly orientable thermoplastic copolymer is polyethylene.

4. A packaging component as set forth in claim 1, wherein said molecularly orientable thermoplastic polymer is nylon.

References Cited UNITED STATES PATENTS 3,003,296 10/1961 Feldkamp et al. 206-46 3,148,773 9/1964 Baumer 20646 3,150,854 9/1964 Jamieson 248345.l

OTHER REFERENCES Modern Plastics, pp. 166, 167 (10/19/63).

THERON E. CONDON, Primary Examiner.

J. M. CASKIE, Assistant Examiner.

Claims (1)

1. A PACKAGING COMPONENT FOR RECTANGULAR BRICK PACKAGES OF THE TYPE CONSISTING OF SEPARABLE BRICK PACKS DISPOSED IN SIDE-BY-SIDE CONTIGUITY, EACH PACK BEING BANDED BY A STEEL STRAP, SAID PACKAGING COMPONENT COMPRISING: AN ELONGATED MOISTURE-IMPERVIOUS ABRASION-RESISTANT CORNER PROTECTOR AND TENSIONING STRIP ASSUMING AN L-SHAPE CROSS SECTION AND ADAPTED TO OVERLIE ONE LONGITUDINAL CORNER EDGE OF THE PACKAGE AND TO EXTEND UNDER TENSION BETWEEN AND BENEATH ADJACENT STEEL STRAPS, SAID STRIP BEING FORMED OF A MOLECULARLY ORIENTABLE HEAT-FUSIBLE THERMOPLASTIC POLYMER HAVING THE INNER PORTION THEREOF SET WITH A MOLECULAR ORIENTATION WHICH IS LARGELY LONGITUDINAL BUT WHICH PRESENTS SUFFICIENT TRANSVERSE MOLECULAR ORIENTATION TO ENABLE THE STRIP TO BE FOLDED LONGITUDINALLY WITHOUT SPLITING, AND HAVING SUFFICIENT RESISTANCE TO ELONGATION-IN-TIME THAT IT WILL NOT STRETCH

Images