US2897959A

US2897959A - Shock absorptive packaging

Info

Publication number: US2897959A
Application number: US311871A
Authority: US
Inventors: John L Gretz
Original assignee: BF Goodrich Corp
Current assignee: Goodrich Corp
Priority date: 1952-09-27
Filing date: 1952-09-27
Publication date: 1959-08-04
Anticipated expiration: 1976-08-04

Description

ug. 4, 1959 J. L. GRETz SHOCK ABsoRPTIvE PACKAGING 2 Sheets-Sheet 1 Filed Sept. 27, 1952 ATTORN EY Aug. 4, 1959 .1. L.. GRI-:TZ

SHOCK ABsoRPTIvE PACKAGING 2 Sheets-Sheet 2 Filed Sept. 27, 1952 lNvENToR 509mm x't BY I ATTORNEY United States Patent() 2,897,959 f SHOCK ABsoRPTIvE PACKAGING .lohn L. Gretz, Milford, Conn., assignor, by mesne assignments, to The B. F. Goodrich Company, Akron, Ohio, a corporation of New York Application September 27, 1952, Serial No. 311,871

1 claims. (c1. 20s-4s) -This invention relates to cushioning pads and to the art of making and utilizing the same particularly in the packaging of fragile articles in a container for protection against damage from shocks and jars in transportion or handling in storage.

One object of the invention is to provide cushioning pads made of a material of extremely low density and light specilic gravity, such as so called rubberized curled hair or equivalent spot bonded filaments, in which the nterlocked filaments are so directed in relation to the pad surfaces that the sparse lamentary substance of the material suffices without reinforcement to perform an unusually efficient cushioning function.

A further object is to utilize in my improved pad rubberized curled hair that has been prefabricated in the form of a continuous straight edgedthickish sheeting, web or strip, whereby to avoid the cost Vof molding rubberized hair into specially shaped bodies ,to serve as cushioning pads. v i

A further object is to establish a controlled degree of density in a cushioning body derived from .a thick web of rubberized curled hair material by coiling a long strip of such material in convolutions into av spirally wound` roll having flat broadside faces composed of the edges of the coiled strip, whereby the tightness with which lthe strip is coiled can determine .the density of the material of the roll that is to be used as a cushioning body.

A further object is to so orient the spot bonded, vinterlocked filaments of the lilamentary material in relation to the `llat surface of the rollk as to provide a maximum resistance to compression of the thickness of the roll, or cushioning pad, for a materialof its composition and density wherefore a cushioningperformance ofunusual eciency is obtained. i A further object is to so arrange improved cushioning pads, made of rolled stock as above described, in space between rigid walls .of a shipping or storage container and a fragile article to be floated in such space, that the pad or pads till such spacefin a manner topresent one ilat face of the roll toward or against Athe container wall and its other at face toward or against the load chamber occupied by the fragile article. Y

A still further object is to combinevthe above said cushioning pads in a container with cushioning pads of other types having a like cushioning property of similar characteristic. u p .n

The foregoing and .other advantages of the invention will appear ingreater detail from the following description of successful embodiments ofthe .present im-` provements having reference to `the appended :drawings wherein: e

' Fig." 1 is a perspective viewshowing in exploded y.relal tion packaging supplies forl practising the invention4 including a shipping container with Vits cover v.and vcover fastening' means,` a load articlefandspace -filling lcush ioningl bodies.

2,897,959 Patented Aug. 4, 1.959

sembled `into a complete and closed shipping package embodyingl the invention.

Fig. 3 is a graph explanative of advantages of the invention.

Fig. 4 is a perspective view of a cushioning body cut from a web of elongate resilient curly filaments interlocked and spot bonded together in accordance with this invention.

Fig. 5 illustrates a diiferent form of shipping package incorporating the invention with the outer wall of the container partially broken away to expose a loa'd article packed by a practical use of -my improved cushioning structure.

Fig. 6 is a -view taken in section on the plane 6-6 in Fig. 5 looking in the direction of the arrows.

Fig. 7 shows a cylindrical container with its Wall broken away to expose a still different arrangement of package cushioning construction embodying the invention.

Fig. 8 is an exploded view of the cushioning bodies removed from the container of Fig. 7.

In most cushioning applications the primary function of cushioning material is not only to vkeep the contents of a shipping container from shaking around thereinv but is also to absorb energy created by impact against the supporting frame or container or by violent'acceleration or deceleration of the load to which the materiallis subjected. Resulting compression of the cushioning ma` terial should reduce such energy to a force less than that which can safely be tolerated by the 4cushioned contents or load article.

Properties of packaging material that are desirable include sufficient resilience in the cushioning body ofthe material to insure its full return to original dimensions' after being repeatedly compressed, good damping capacity in the sense of sufficient reluctance to rebound too abruptly in recovering from its compression, and the ability to absorb a high proportion of the aforementioned energy generated by impact under a given relationship of 'load weight to the resulting compressional deiiection of the cushioning body.

An important property of cushioning material is its compression resistance. Compression resistances vary both inmagnitude and in eiiiciency for various types and densities ofjcushioning materials, so that judicious selection of the material with the correct values for each of these variations is the basis of cushioning design. For any type of material, the magnitude of compression resistance varies directly with the density but the efficiency usually varies with the type of cushioning material.

Whereas the concept of magnitude of compression resistance expressed as pounds per square inch' at a cer` t-ain resulting deflection expressed as inches or percent ing Hookes Law has a linear compression resistance ratel in which doubling the load doubles the deflection,

tripling the load triples' the deflection, and so on to the limits of the spring. At any combination of load and deection, the work done on the spring is l of the product of load and deection whereas ideally the work could be the product of they load `times the deflection; thus the eiciency of work vor energyfstorage is` 50%.

4Efficiency is readily determined foi any cushioning material by plotting the increasing incrementsfofmload as. ordinates, and the resulting deflections of the material as abscisse to obtainra compression resistance chair# acteristic as represented in Fig. 3. Since the area enclosed by the curve, the X-axis and the abscissa for the desired deflection, represents the work done lonv 3Y cushioning when compressed to the desired deflection, eiciency may be computed by dividing this area by the maximum work obtainable which equals the product of the load times the deflection. Curve 46 'ini Fig. 3, representing a typical cushioning material, would have an efficiency of'approximatelyl25%` at 60% deection because only 4% of the possible 3X6 or 18 squares are under the curve 46. i

- Commerciallyavailable cushioning materials as heretofore used are generally less than 50% eicient. However, with a ilamentary body so constructed that the majority of its filaments are oriented perpendicular to the face of the body that is subject to loading, most of the filaments will act as individual columns under compression in that they will offer a high initial resistance until they buckle and bow or bend individually. Following this, large deflections will occur for small additional increments of load. The result is a compression characteristic enclosing more than 50% of the pos'- sible chart area under the graph line. The compression resistance curve would become similar to curve 47 in Fig. 3 and which, by the method described in the preceding paragraphs, has lan eiliciency of 70%. This results in highly eflicicntrbulk cushioning material. In the web, sheet or strip of rubberized hair from which I propose to form a cushioning pad by coiling it into a roll, the direction of fiber lengths is mainly parallel with the surface of the face of the sheet material'which are to become curved surfaces in the roll rather 'than perpendicular or normal to such surfaces. This disposes the lengths of the fibers or laments into directions mainly paralleling the axis of the roll.

According to the broad principles above outlined theremay be fabricated and used as cushioning material a yieldable body or bodies such as those designated 12 in Figs. 1 and 2. Each of these bodies has 2,897,959" -s -I A g edge surfaces 16 of the cushioning bodies will be of shape to conform to the inside of the container wall. I then cut openings 18 through a plurality of such cushioning bodies and stack the bodies with their broadside faces together forming a laminate assembly in which the openings through the individual cushioning bodies are bounded by the inner edge surfaces 16' of the bodies and combine to form a hollow, load nesting space within.which a load article can be lodged and resiliently constrained. The inner edge surfaces 16', rather than the broadside faces 14 of the bodies, face such load nesting space and impart to the load article in diminished magnitude whatever shock forces are derived at the outer edge surfaces 16 from the wall of the container, such forces being transmitted to the load article through the sparse filamentary structure of the cushioning bodies 12 and causing the filaments to ilex mainly in response to forces of columnar compression.

broadside faces 14 joined by crosswise extending edge v surfaces 16 and 16'. The material as best shown in Fig. 4 comprises intermingled elongate resilient curled bers or filaments interlocked by spot bonding them together in a manner to orient and maintain the laments in such positions that their lengths extend mainly`in directions more nearly parallel with said broadside faces 14 of the b ody than with the edge surfaces 16 thereof, as represented in Fig. 4. The fibers or filaments can to `advantage constitute curled animal hairs, such as horse tail or horse mane, interlocked by bonding together at separated spots their respective coatings of vulcanized latex applied so sparsely that spacious unclogged spacesv or voids permeate the material making room for free individual flexing of the filaments therein. l

By `arranging' elongate spot bonded filaments in stratified disposition mainly and approximately in parallel relationship to the broadside surfaces of a cushioning body as aforesaid, and by disposing such cushioning body so that its edge surfaces toward which the lament ends are mainly directed, rather than its broadside faces, are respectively constrained by the wall of the lshipping container 17 and presented toward the load article, greatly increased protection of the load article results with use of a cushioning material of reduced weight and lowered cost.

I.prefer to produce such material initially in the form of a continuous thick sheeting or Web which may be done by a fabrication method explained in greater detail in U.S. Patent No. 2,580,202. Such method tends strongly to orient and maintain the filaments positioned with their lengths extending in directions more nearly parallel with the top land bottom surfaces of theY web than in directions crosswiseV the thickness of Vthe web; Specifically I prefer to .cut the aforesaid cushioning bodies from the aforesaid. web. The broadside faces 14 of the former will be the residium of the original top and bottom vsurfacesl of the web. The peripheral In Figs. 1 and 2 the load article comprises a delicate instrument 20 fixed on a base plate 22. The assembly of the particular instrument and base plate herein shown calls for a nesting shape of load chamber 18 which may be bluntly triangular in horizontal cross section so that the edge surfaces 16 of the cushioning bodies 14 abut the load article all about to constrain it resiliently in all lateral directions.

In Figs. 1 and 2 there is shown a special adaptation of this invention embodied in a roll 24 made by coiling a narrow strip of the aforesaid web material in convolutions with the broadside faces 26 of the original strip wound progressively upon themselves with suicient tightness to compress the normal thickness of the strip in each convolution to selective degree thereby to increase the density of the cushioning substance throughout the roll. 4The exposed edge surfaces 28 fall flush so that they combine to form at broadside faces of the roll. v

When so coiled into a roll with a selective degree of tightness the outer end 30 of .the coil strip can be cemented or staplcd or sewed to the underlying convolution thus to anchor it against uncoiling movement. This will preserve whatever degree of compression is originally set up in the ilamentary material of the strip by maintaining the tightness with which the strip was pulled in winding it when originally coiled. Need for use of an adhesive along any continuous extent of the overlapping surfaces of the spiral convolutions is thereby eliminated because each'convolution tightly imprisons all convolutions internal thereof thus placing the entire length of the coiled strip under self squeezed compression. f

Ofprime importance is the fact that this method o fabrication using a resilient, compressible prevulcanized material such as rubberized curled hair will produce pads of density that is mechanically determined and mechani-j cally maintained by various degrees of compression resistance greater than that of the original prevulcanized material which is of constant density. The control over the density of the rolled pad depends entirely on the length of the strip used to produce the final pad, the' thickness and density of the strip, and the final diameter of the rolled pad'which is determined by the tightness of rolling. A'pictorial'compariso'n of the compression resistance of pads of various densities rolled from various length strips of the original material vis represented by

graphs

47,48 and 49 in Fig. 3.

Having formed a 'roll of rubberized hair as described and recalling that the ends of the hair are presented toward the at broadside faces 28 of the roll, I have found that the roll is capable of serving very vefficiently as av cushioning pad by inserting it between the container 17 andthe' chamber containing

load article

20, 22 as shown in Fig. 2. A pad like 24'can thus be used at the top and bottom of container 17 after'which the con- In Fig. 5 a scheme of packaging is shown `wherein pads such yas 24 serve as the sole space filling material between the flat yfaced load article 36 and the at |Walls 38 of a box-like container. In this instance the pads 2.4 will be cemented, stapled or otherwise xed in position against the container walls 3S and will be somewhat compressed against the load article when the sides of the container are nailed together.

In Figs. 7 and 8 a cylindrical container 40 is seen equipped to cushion the load article 42, which may be a glass vial or the like, by use of pads like 24 at the top and bottom of the container, While the axially intervening space in the container is filled with a laminate of discs such as '12 cut radially into separate adjoining pie-shaped pieces 44.

A comparison of the increased eiciency in safe and effective cushioning perfomance resulting from this invention as compared with Vformer practices in the art is fairly represented by the pictorial symbols in the chart of Fig. 3. Here the ordinates, or vertical distances on the chart to the

Various graphs

46, 47, 48 and 49 from the zero abscissa or base line A-A, are proportional to increments of increase of weight or compressive force of load in pounds per square inch exerted on cushioning bodies of basically similar composition when such bodies are variously positioned and conditioned between container wall and load article. The abscissa or horizontal distances to the same graphs from the zero ordinate or upright line 0-0 are proportional to corresponding increments of Iincrease of deection of the cushioning material in terms of percentage decrease of original dimension of the cushioning body in the direction the load force is applied, 'which direction as indicated by arrows F is assumed to 'be downward.

VIn the case of a disc 12, or laminate of such discs whether or not divided into sections like the pieces 44, disposed as represented on the chart the particular kind of cushioning material herein concerned yields too readily to initial increases in load lforce (F) acting against the broadside face of the pad as represented by graph 46. This results in poor cushioning action because of inability to absorb shock effectively until the cushioning body or bodies become compressed to say a half of their original unloaded vertical dimension. In contrast, a cushioning pad of the same overall size and shape constructed like the roll 24 does not yield with anywhere near the readiness responsively to initial increases in load force (F). As a result good cushioning action immediately comes into play to oppose initial increase of load force throughout even the first 20% deflection of the cushioning body. In the chart the amount of shock energy which the diverse arrangements of iilaments in

cushioning bodies

44 and 24 can eiectively absorb is represented by the entire area that fills the space between each of the graphs 46 or 47 and the base line or zero abscissa A--A. Thus much more desirable shock absorbing action can be performed by the roll 24 than by discs 44 in opposition to load forces acting in the direction of arrows F.

When the roll 24 is 'Wound more and more tightly upon itself the graph 47 may become more like graphs 48 and 49, showing that increase in the unloaded density of the cushioning material does not change the desirable characteristics of cushioning performance evidenced by graph 47. Concrete values of the increasing load force magnitudes and of the resulting increases of compressive deflection are marked on the chart for convenience of reference and without intention of thereby limiting the scope of the claims to this invention. They indicate values iwithin a range of load force intensities that is practical in package cushioning by use of the material and arrangements herein involved.

One advantage of the rolled pad embodiment of thev invention is that it constrains the filaments in a. manner to resist their tendency to deflect laterally and buckle when subjected to columnar or endwise load thrust. Side sway in the cushioning body is thereby inhibited and the performance of the cushioning body becomes more stable and dependable. The rolled strip form of cushioning body is also found to damp out initial shock impulses in a manner to inhibit repetitive rebound thus reducing the extent of vibration to which the load article is subjected.

As a different way of attaining these objectives, strip stock such as herein shown coiled into the roll 24 may instead be folded back and forth upon itself in successive plies which can be pressed together by stitching through the plies to preestablish compression of material in a pad so composed or in a laminate of relatively overlapping but unfolded pieces of the strip stock when so stitched together.

As a nonlimiting example of packages sizes in which the invention can to advantage be embodied the container of Figs. 1 and 2 may measure 165/5" high by lOl/2 in diameter with a load article size of 81/2" by 4 by 43716 weighing 2.81 pounds. The roll 24 may measure 41,46" thick by 10% overall diameter and weigh 0.40 pound. The laminate of side pads 12 may measure 81/2" high by 10S/s in overall diameter and contain a cutout 3% by 4". The roll may be round, oval, or rectangular.

Pads comprising a roll or rolls made as herein explained serve the advantages explained in numerous uses aside from packaging such as in use as upholstery filler, rugs and rug underlays, vehicle mats, marine fenders, crash pads, shoe soles or platforms, etc.

Many variations in and departures from the shapes, proportions and arrangement of parts herein chosen to illustrate the principles of the invention can be resorted to for practicing such principles, wherefore the appended claims are directed to and intended to cover all substitutes and equivalents that fairly come Within the broadest interpretation of the 'combination defined by the claims.

I claim:

l. In shock absorptive packaging, a cushioning pad comprising a coiled strip of open ilamentary material wound upon itself about an axis to forma roll, said material incorporating a spaciously intersticed network of mutually entangled long resilient filaments, each having a thin all-over coating of a vulcanized dispersion of elastomer bonding said filaments together only at spots of mutual contact or close proximity in such relationship that a preponderance of said filaments have their lengths oriented in directions paralleling said axis of the roll, and said coiled strip being wound upon itself with suicient tightness to compress the inner coils of the said roll thereby to cause the said spot bonded filaments to bow individually in the said interstices of the said network of the said material.

2. In shock absorptive packaging, a cushioning pad as dened in claim l, together with means fastening only the outer coil of the said roll to an underlying coil of said roll wherefore rto maintain said tightness.

3. In shock absorptive packaging, a cushioning pad comprising a straight-edged coiled strip of iilamentary material wound directly upon itself without interliner in a plurality of convolutions about an axis to form a roll of less thickness than its axial length in which the straight strip edges of adjacent convolution are substantially ush and combine to form opposite broadside surfaces of the pad lying perpendicular to said axis, said material comprising a spaciously intersticed network of mutually entangled long resilient filaments, each having a thin allover coating of a vulcanized dispersion of elastomer bonding said filaments together only at spots of mutual contact or close proximity and in such relationship that a preponderance of said filaments have their lengths oriented in directions paralleling said axis of the roll.

l4. A shock absorptive compressible resilient cushioning pad comprising a roll having opposite ends forming at parallel surfaces adapted to vbear the compressive 7 forces of a load, said roll being formed by a strip of material composed of a self-coherent spaciously intersticed network4 of mutually entangledv long resilient filaments each having a Ithin all-over coating of a vulcanized dispersion of elastomer bonding said filaments together only at spots of Amutual contact or close proximity, and said strip being wound closely upon itself about an axis in a plurality of convolutions mutually having direct surface-to-surface contact, the edges of said strip lying mutually ush to form and dispose said fiat parallel load bearing surfaces of said roll in perpendicular relation to said axis, the said lilaments having a preponderance of their lengths oriented in directions more nearly parallel with said axis than with said load bearing surfaces. 5.4In shock absorptive packaging, a cushioning pad comprising a straightfedged coiled strip of lamentary material Wounddirectly upon itself without interliner in a plurality of convolutions about an axis to form a roll of less thickness than its axial length in which roll the straight strip edges of adjacent convolution are substantially flush and combine to form opposite broadside suryfaces of the pad lying perpendicular to said axis, said material comprising a spaciously intersticed network off mutually entangled long resilient laments, each having a thin all-over coating of a vulcanized dispersion of elastomer bonding said filaments together only at spots of mutual contact or close proximity and in such relationship that a preponderance of said laments have their lengths oriented in directions paralleling said axis of the roll, together with a container housing said pad and a load chamber and having a rigid wall flanking one broadside surface of said pad on the opposite side of said pad from said load chamber while the opposite broadside surface of said pad borders on said load chamber, whereby a load occupying said chamber is separated from said container wall by the said thickness of said roll so that shock forces transmitted through the thickness of said roll between said load chamber and said container wall act in the said direction in which a preponderance of the lengths of the said laments are oriented.

6. The combination defined in claim 5, together with a load article in the said chamber, and space filling bodies of the same kind of vilamentary material of which 4the said coiled strips are composed interposed between said load article and a related wall of the saidtcontainer other than the said rigid wall, said ybodies having theiry spot bonded filaments so oriented that a preponderance of the lengths of said filaments extend in directionsv normal to said related Wall of the container.

7. The method of predetermining and maintaining a selective degree of density and cushioning resistance in a discal shaped pad of highly compressible rubberized hair which includes the steps of, producing a exible strip of spot bonded rubberized hair of substantially uniform skeletal density having a width equal to the desired thick ness of the pad, coiling a selected length of said strip into a plurality of overlapping convolutions with sulicient tightness of winding of said strip upon itself to compress the rubberized hair and reduce the thickness ot the coiled strip thereby to form a roll having a thickness equal to the lwidth of said strip and having a cushioning strength predetermined by the degree of tightness with which said strip is wound upon itself, and securing an outer convolution of said roll to an underlying convolution of said roll in a manner to maintain the said tightness.

References Cited in the file of this patent UNITED STATES PATENTS 546,009 Graves Sept. 10, 1895 1,567,991 Clark Dec. 29, 1925 1,611,575 Aulbach Dec. 21, 1926 1,808,530 Cooley lune 2, 1931 1,949,259 Salsman Feb. 27, 1934 1,988,843 Heldenbrand Jan. 22, 1935 2,015,268 Hammond Sept. 24, 1935 2,270,043 Fourness Jan. 13, 1942 2,353,821 Fourness et al July 18, 1944 2,516,124 Kishibay July 25, 1950 2,580,202 Talalay Dec. 25, 1951 FOREIGN PATENTS 771,011 France July 16, 1934