US1969152A - Seal-joint - Google Patents

Description

H. C. PORTER Aug. 7, 1934.

y Filed Feb. 5, 1932 Patented ug. 7, 1934 UNITED srAras PATENT OFFICE V1,909,152 SEAL-.I OINI Howard C. Porter, La Grange` Park, 111., assignor to signada steel strapping Company, Chicago, f Ill., a corporation of "f Application February 5, 1922, Serial No. .591,003

ivry invention relates to seal-joints. Y More particularly it relates to seal-joints for interconnecting overlapped portions of package binding straps, which are made by a continuous 6 edgewise crimping action with a ysuitable tool to form in the strap complementary interlocking separation-resisting distortions.

Patents Nos. 1,038,108 and 1,252,680 issued to E. E. Flora set forth joints of this general type. -10 In general, the joints of this type have consisted of complementary distortions one in each strap portion, and also in an encircling sleeve if one is used, characterized by angularly related interengagingmarginal' nanges disposed obliquely to :l5 the length of the strap and substantially at `right angles to the normal plane of the strap and by relatively loosely related outwardly projecting humps in the region of the strap between the J marginallanges. These humps or outward offsets were formed incidentally to the inward edgewise crimpingaction which formed the marginal anges and contributed little, if anything, to the strength of the joint. In other words, the resistance to longitudinal separation of the overlapped .25 strap portions when the strap was subjected to tension was afforded solely by the unaided capability of the engaging or intertting marginal flanges to retain the initial angularity (i. e. longitudinal obliquity) and thereby prevent them .m'from slipping by one another. Under tension the humps would atten out relatively easily whereupon the entire strain' would be thrown upon the flanges and, because those anges were unsupported or lacked proper `reinforcement, they would become less angular or oblique longitudinallyand the strap portions would slip vby each other,i. e., the joint would fail. This peculiarity of action when under tension was an inherent weakness in' these prior joints, and the over- 40 lapped strap portions in the hump region were so loosely related that friction between them to resist longitudinal separation was practically nil. The joint set forth in Patent No. 1,826,018 to E. C. Pagel, which was designed to avoid .these difllculties of the Flora joint, is one wherein the action of the intertting marginal flanges is supplemented by additional deformations providing extra interengaging shoulders in the humped portion of the distortions. Such joints are stronger theoretically and in practice have been found to give improved results with very soft strap. But with normal commercial grades of package binding strap it has been found that joints of the Pagel type cannot be produced with tools of feasible portable sire and weight. Furthermore, it has been found .that joints of the general character of the Pagel joint are unsatisfactory unless encircling sleeves are incorporated therein, because without a sleeve the overlapped #il strap portions separate laterally relatively easily appearwhen the strap is subjected to tension. Such lateral separation weakens or destroys completely vtbe separation resisting action of the interiitting or interlocking distortions. l

One of the objects of my invention is to pro- 05 vide an improved joint for.joining overlapped portions of metal package-binding strap, with or without an encircling sleeve.

Another object is to provide a joint which is free from the objectionable features of previous joints heretofore mentioned. j

Another object is to provide a -joint having substantially the strength of the undistorted strap.

A further object is to provide a joint which '15 may be produced'with tools of feasible size and weight..

Other objects and advantages willhereinafter In the drawin Fig. 1 is a plan vlewof a tandem-related pair of seal-joints embodying my invention;

Fig. 2 is a side elevation thereof; Y

Fig. 3 is an enlarged transverse section through one joint taken on the line 3-3 of Fig. 2;

Fig. 4 is an enlarged longitudinal section taken on the line 4--4 of Fig. 1:

Fig. 5 is an inverted plan view of one of the joints shown in Figs. 1 to 4; and

Figs. 6 and 'l are cross section and longitudinal sectional views, respectively, -of a pair of tandem sleeveless joints.

Referring to the drawing, the joint is made by and between two overlapped or superposed portionsof at metal binder strap 10 and 1l and an encircling metal sleeve 12." Such a sleeve may be of the general types set forth in Flora Patent No. 1,252,680 or J. W. Leslie Patent No. 1,445,330. After encircling a package with the binder strap, tensioning the strap to the desired degree and applying to the overlapped portions thereof the metal sleeve the joint is made therein by a. suitable tool, preferably by a tool such as shown inmy copending application Serial 588,556 filed January 25, 1932.

In forming each joint the opposite edge portions of the overlapped strap portions are bent inwardly (i. e. toward the center of the binder) to form marginal upstanding anges 32 substantially perpendicular to the original plane of the strap and curving continuously relative to either the length or the breadth of the strap. At each end this curve is outwardly convex, the mld-portion being outwardly concav These upstanding anges are pressed inwardly toward each other a sucient distance to cause the overlapped layers of the strap to be rolledor folded back tightly upon themselves into a .compact longitudinally extending rib 28 at each edge of the joint. The

vertical marginal flanges 32 are substantially cony120 tinuously curved'in relation to the longitudinal axis of the strap, as shown in Fig. 5 and by dotted lines` in Fig. 1, and constitute interengaging K shoulders disposed obliquely to the direction of 5 tension. Themarginal rolled portions 28 are held in the form of tightly compressed ilat ribs substantially coextensive longitudinally withthe inwardly curved or obliquely related edge iianges 32.

The top surface of the joint lying crosswise be-l tween the ribs 28 is oiset outwardly above the original plane of the strap forming a substantially continuously curved outwardly convex hump 34 extending across the joint between ribs 28 and substantially cocxtensive longitudinally of the strap with the inwardly bent vertical anges 32 and consequently also with the ribs 28.

The outwardly curved hump 34 is limited longitudinally of the strap at predetermined points 35, so that this upward formation is uniform re- 20 gardless of the variations in stiffness of the materials used for the joint; whereas in the prior joints of the Flora type the length of the hump would vary with the stiffness of the strap (and the sleeve one was used), the stiffer the strap and sleeve the longer the hump and the greater its extension beyond the ends of the marginal flanges.

Similarly the longitudinal ribs 28 at the sides of the vertical curved hump 34 are formed in a. predetermined position substantially to coincide in length with the length of the hump. K And in like manner the curved vertical flangesk 32 are formed substantially in the same predetermined longitudinal length as the lengths of the ribs and the hump. In this way the curved upstanding marginal ilanges 32, the substantially parallel longitudinal ribs 28 and the outwardly convexed hump 34 are inter-related in dimension independently of the variations of material used in forming the joint.

The portions of the joint at each end of the distortions are held in substantially nat undeformed shape and the lines oi junction 35 between the at undeformed portions and the central convex hump 34 are slightly relieved to allow a slightly gradual curvature at the corners 33 where the various rib forming components blend into. each other, but not suiiiciently relieved to allow the longitudinal length of any of the rib components and anges of the deformed portion substantially to vary one from another. f

From the above description it will be clear that the vertical' oiiset constituting theoutwardly curved hump 34 will be supported and maintained in its convexly curved shape by the stiffening effect of the vertical marginal flanges 32 thereunder. Similarly the longitudinal curvature of the vertical marginal anges will be supported and maintained by the stlffening eiect oi the compactly folded and fiat longitudinal ribs 28. Furthermore, the at longitudinal ribs 28 will be maintained in their flat and tightly tted or compacted condition and strengthened againstI opening or spreading by the longitudinal reinforcing action of 4the vertical flanges 32 and also the reinforcing action of the hump 34 in a horizontal plane. 'I'he flanges, ribs and hump, which constitute the three eective components of the joint are therefore mutually inter-related and mutually support, sustaiizi and reinforce each other. The complementary distortions in the two overlapped strap portions constituting the joint are therefore securely locked together and there is no tendency for tension in the band to cause the joint to fail by successive failure of the various inter-related components; andthe inherent weaknesses of the original Flora joint heretofore described are completely eliminated.

Tension applied to my improved joint is resisted by the inwardly curved or oblique edge portions or upstanding marginal anges 32, which withstand straightening because of the support or reinforcement accorded thereto by the ribs 28 and the hump 34. The tension is also resisted by the central portion of the straps oiset into the hump 34 which resists straightening or attening because of the support or reinforcement afforded thereto by the ilanges 32 and the ribs 28. Each portion of the cross section of the strap therefore sustains a considerable share of the tensional load applied to the joint and because of such distribution of the tensional load there is less tendency for the edge portions to become straight because of undue concentration of load thereon. All of these factors contribute to prevent the straightening ,of the marginal flanges and consequently any reduction of the v oblique angles at which the abutting ange shoulders are interlocked.

If the longitudinal tension of the strap across the hump 34 is increased excessively, the central portion of hump 34 may buckle downwardly to some extent but, even so, no distortion will result in the interiocked ribs 28, flanges 32 and the adjoining portions of hump 34. Under such condition the joint may be bent slightly along the longitudinal center line ofthe joint, but nevertheless it retains and maintains substantially unimpaired itsy full holding power because the interlocking relationship of the several distortion components resists any reduction in the oblique angle to which the interlocking ange shoulders are abutted.

Furthermore, since tension does not alter and reduce the holding power of the abutting flange shoulders, it is not necessary to form these upstanding anges in such exaggerated shapeY that they will still retain substantially full holding strength after tension has changed them. It is y therefore possible with this joint to provide full joint strength with a relatively much smallerl amount of edgewise odset than was the ease in previous joints. In other Words, it is not necessary to so deeply indent the edgewise crimps in order to provide joints of satisfactory strength,

as is the` case with prior joints. The result is that a lesser cunt of the strap is folded into the vertical upstanding ilanges 32 and the maximum thickness or height of the joint can be reduced beyond that possible with previous joints.

And because of the requirement for relatively less exaggerated deformation of the band, a less intense deformation can be made than was possible with previous joints and less work is requiredin the operation of the joint forming tool to produce such deformation. Consequently it is possible with my new joint to provide satisfactory joint strength with considerably less effort than was required with previous joints. The resuit is that very strong joints may be made with tools which are suiiiciently light in construction and weight to render them easily portable.

It is also evident from the above description that the components of the joint deformation distribute the crimping or shortening action on the straps being joined substantially uniformly throughout the 'area being deformed, whereas previous joints required the maximum crimping and shortening action to be applied and concentrated primarily to the edge portions oi the strap.

As a result of the unequal shorts, straps iny if itially tensioned almost to the breaking point are actually broken when attempts are made to produce prior joints therein, because' the added tension caused by the strap shortening action of joint formation is concentrated at the edges. The resultis that because the edges can bear no more strain a fracture starts there. On the other hand, with my improved joint the strap shortening (and consequently the tension increasing) distortion is ksubstantially uniform throughout the cross section of the joint and each part takes its uniform share of the increased tension due to the shortening action of joint deformation. Consequently my improved joint can be successfully rmade in strap that is tensioned substantially to its breaking point before the joint is formed; a condition impossible with prior joints of the Flora type. Therefore, my joint allows the utilization of the full strength of the undeformed strap and, for any given required maximum tension a smaller strap may be used, whereas with prior joints it was necessary to use a band capable of withstanding a greater tension than the maximum tension to which it `wasI to be subjected.

In the case of joints formed in tandem, as illustrated, each being made as described, this invention provides a joint which will distribute the tension strain substantially equally throughout both joints. allowing the joints to be actually intersupporting. InY previous joints the tension effect causing a reduction in the holding power of the abutting shoulders, causes the two joints to pull out successively one after the other and the total holding power of such two joints in tandem is therefore only ing power of a single joint alone.

The inter-related dimensions and configurations of the component parts of the interlocking distortions constituting my joint will cause all portions of the contacting surfaces ofthe straps to be tightly squeezed together or compacted in high frictional relationship.l This characteristic materially increases the frictional components of the joint beyond that which is possible with previous joints in which certain components of the deformations are folds or wrinkles in the overlapped strap portions without any appreciable surface frictional contact therebetween. It is therefore possible to use 'my joint to produce increased joint strength on those grades of commercial binder strap which are' provided with lubricated surfaces or surfaces with a low coefficient of friction,grades o f strap which are frequently very useful because of the ease with which such straps may be drawn around corners of packages during the tensioning operation.

By providing relatively sharp and continuous curves in the vertical Aupstanding flanges 32 rather than a configuration which included a region of considerable length substantially parallel to the longitudinal axis of the strap', as was the case with previous joints, my new joint may be effectively produced in harder and more brittle grades of strap than was possible with prior joints. This is due to the fact that in my joint throughout most of the vregions where the strap is most sharply or abruptly folded or bent, .such folding or bending takes place at an angle to the longitudinal axis of the strap-i. e. at an angle to the grain ofthe strap-and hard and brittle strap dependent angularly slightly greater than the hold-I merely casual uncontrolledv can in this way be more easily and sharply bent without danger of fracture than is the case where the folds or bends are to a greater extent parallel to the longitudinal axis of the strap.

The sharply concave or recessed shape of the vertical flanges 32 and the overhanging coextensive rib 28 and the continuously curved convex hump 34 combine to provide a strong integral structure somewhat resembling a box corner and possessing the inherent strength thereof. This integral structure is capable of withstanding the strongest tension which can be applied to the strap and still remain substantially unchanged in holding power, even when the tension in the strap causes the hump to buckle along the center line of the strap. n

The sleeveless joint illustrated in Figs. 6 and 'i has essentially the same characteristics and properties as the sleeve type heretofore described. It has the longitudinally coextensive and inter-v related upstanding marginal flanges 32', flat compact ribs Z8 and continuously curved convex hump 34. The sleeveless joint is not quite as strong as the sleeved type, because it does not have the reinforcing effect of the additional sleeve metal, but it is a satisfactory and effective joint where slightly less strength is acceptable.

Having thus described the nature and two embodiments of my invention, what I claim and desire to secure by United States LettersPatent is as follows:

1. A strap joint comprising overlapped portions of metal strap deformed to provide complementary obliquely` related upstanding marginal flanges and compactly rolled marginal'ribs, the ribs and flanges being substantially coextensive longitudinally of the strap and mutually to reenforce each other to prevent tension in the strap lessening the obliquity of the flanges.

2. A strap joint comprising overlapped portions of metal strap deformed to provide complementary obliquely related upstanding marginal flanges and compactly rolled marginal ribs and a hump offset from the normal plane of the strap', the ribs and flanges sive longitudinally of the strp'and reenforcing each other to prevent tension in the strap lessening the effectiveness of the joint to resist the tension.

3. A strap joint comprising overlapped portions of metal strap deformed to provide complementary `obliquely related upstanding marginal flanges and compactly folded marginal ribs and a hump offset from the normal plane of the strap, the flanges and hump being substantially coextensive longitudinally of the strap and mutually reenforcing each other to resist'the tendency of tension in the strap to lessen the Obliquity of the flanges.

4. A strap joint comprising overlapped portions of metal strap deformed to provide complementary obliquely related upstanding marginal flanges and compactly folded marginal ribs and a hump offset from the normal plane of the strap, the hump and ribs being substantially coextensive longitudinally of the strap and mutually cooperating with each other and the flanges to resist the tendency of tension in the strap lessening the obliquity of the flanges.

HOWARD c. PORTER.

being substantially coexten`

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