US2830344A - Seal blank - Google Patents

Description

April 15, 1958 G. A. chossv SEAL BLANK Filed Feb. 10, 1953 I SEAL BLANK George A. Crosby, Park Ridge, IiL, assignor to Signode Steel Strapping Company, Chicago, Ill., a corporation of Delaware Application February 10, 1953, Serial No. 336,678

' 1 Claim. (21. 24 23 The present invention relates to an improved seal blank for use in forming a seal or joint between overlapping ends of metallic strapping used for binding a bundle or like object.

Although a seal blank constructed according to the present invention has a wider use, its principal utility and advantage is in that it can be formed into a joint in a position closer to the bundle than is usual and is particularly well adapted for use with magazine type tools and automatic strapping machines, such as the type forming the subject matter of the copending applications of John H. Leslie II and George A. Crosby, Serial Nos. 48,448 and 134,526, filed respectively on September 9, 1948, and December 22, 1949, now issued as Patent Nos. 2,707,429 and 2,707,430, dated May 3, 1955, respectively, and assigned to the same 'assignee as this application; also see patents numbered 2,594,397 and 2,497,313 for instance. In automatic strapping machines the strapping is fed in an endwise direction from a coil and passed around a closed track so as to encircle the bundle. As the free or leading end of the strapping overlaps the standing portion, it is automatically grasped and held. A seal blank which has been fed from a magazine and loaded into the folding and deforming jaws of the sealing mechanism is brought into joint-forming position against the strap and its flanges or wings are folded about the overlapping strapping portion. This forms a sleeve encircling the strap so as to prevent movement of the overlapped portions of the strap with respect to each other excepting longitudinally. The machine then automatically pulls backwardly upon the standing portion of the strap so as to shrink the loop of strapping about the bundle and to tension the strapping material. Subsequently the machine automatically. deforms the seal blank and the enclosed portion of the strapping in a well known manner, usually by cutting parallel notches at the side edges through the seal and strapping and then bending the thus formed tabs downwardly so that they are angularly offset with respect to the plane of the main or undeformed portion of the strapping and seal.

In the operation of machines of the type generally set forth above and as more particularly described in the referred to copending applications, it will be recognized that after the seal is folded about the overlapped ends of the quite loose strapping portions, and the loopof strapping is shrunk about the bundle by pulling lengthwise upon one end of the strapping, the standing portion of the strapping is caused to slide for a considerable distance through the sleeve formed by the seal. During this portion of the operation considerable difl'rlculty is likely to be encountered because ordinarily the edges of the Patented Apr. 15, 1958 strapping are tightly pinched by the folded seal. Usually considerable friction is encountered as well as some cutting of the seal. Because of the heat generated by the friction, the speed of operation of the machine cycle is limited since experience indicates that care must be taken not to shrink the loop too rapidly about the object being bound. Also under some conditions the friction thus generated may be sufiicient to drag the seal in an endwise direction somewhat, thereby disturbing its proper position in the sealing jaws. 7

With hand operated magazine type tools much the same activity takes place excepting that the strapping is passed around the bundle and ordinarily much of the slack is taken up by hand before the tool takes over the final tensioning and sealing operations. a

The principal object of the present invention is to pro vide a novel seal blank which overcomes these objections.

An additional object is to provide a novel seal blank which is adapted for use with automatic, folding and sealing jaws which through normal operation of the machine will have its tabs or wings folded about overlapped portions of strapping so as to form a sleeve which does not produce a high order of frictional engagement with the edges of the strapping material.

Still another object is to obtain the above results while at the same time providing an arrangement which enables the joint to be formed in a position closer to the bundle than is customary.

Yet another object is to provide an improved seal blank having the above described characteristics, which can be manufactured at low cost.

Other objects and advantages of the present invention will become apparent from the following description of a preferred embodiment thereof which is illustrated in the accompanying drawings.

in the accompanying drawings, where similar characters of reference refer to similar parts throughout the several views:

Figure 1 is a top view of a seal blank embodying the present invention; V

Fig. 2 is a perspective view thereof with the front edge of the view comprising a transverse medial section which may be considered as taken inthe direction of the arrows substantially along the line 22 of Fig. 1;

Fig. 3 is a view in transverse medial section of the seal shown in Figs. 1 and 2, shown with the strapping and the folding jaws associated therewith at the beginning of a folding cycle; and

Figs. 4 to 6 are similar to Fig. 3 excepting that they show successive stages in the seal forming operation, with the completion of the folding operation being illustrated in Fig. 6.

In the drawings, overlapped strap portions to be sealed together are indicated by the numerals 10 and 12. The

, seal as a whole is indicated by the numeral 14 and is made up of the following portions all integrally formed together from a piece of cut, folded and coined sheet metal of appropriate thickness. The seal has a rectangular, flat, back or central portion 16 which is slightly wider than the width of the strapping with which it is intended to be used. Along its side edges this central portion 16 is integrally joined by rounded corners 15 to a pair of wings 18 which are reverse complements of each other. As supplied for use in the machine these wings diverge outwardly somewhat so that their free ends are farther apart than are the portions connected to the central back piece 16. This is done so that the seal blank can approach the overlapped strap ends laterally and also permits comparatively close nesting or staclc'ngof seals in the magazine of the strapping machine. A seal having the general characteristics outlined above is well known and as pointed out previously usually occasions some pinching at the edges of the strapping when it is folded about the overlapped strap ends. This it has been found is because the metal of whichthe seal is formed tends to bend too sharply at the corners where the wings are joined to the-central portion. Also, the folding jaws need to have overhanging lips at their extreme ends for grasping the edges of the wings so as to limit the outward movement of the blank when the jaws. start to be d the wings toward each other,.and because of these lips the joint ust be rm in a P s ion some di anc om the bundle o pr de the nece sary clearanc f th j s.- hus i nr i cnt bu d e an when t e j i is formed upon a short face of a bundle there may be more slack i e tra pin th n i esi a sa sr the jo is formed.

Theseal blank of the present invention is provided on the inside with coined grooves which extend longitudinally of the seal wings for the full length of the seal blank at a position slightly outwardly of the corners 15. The metal is thus weakened at this position by having its thickness reduced .by a matter of a few thousandths of an inch which aids in producing a greater degree of bending along the grooves 20 than would otherwise take place. In addition to .this, another set of coined grooves 22 are formedparallel to the grooves 20. Unlike grooves 20, however, the grooves 22 are formed into the exterior face of the seal blank in positions close to the free ends. Also the grooves 22 in the present example do not extend the full length of the seal but are confined to about half this distance. They are centered, however, from end to end so as to lie in the middle portion of the seal wings. These grooves 22 are also formed by a coining operation so that the metal is reduced in thickness slightly thereby, while the inside surface of the seal blank remains smooth.

When a seal having these characteristics is loaded by the magazine of a tool or automatic strapping machine into the folding jaws, it appears much as illustrated in Fig. 3.

From an inspection of this figure of the drawing it will i be seen that the back of the seal is supported by a chair 24 and is positioned between a pair of folding jaws 26 which pivot about a pair of parallel axes, one of which is indicated .at 28. '!The overlapped strap ends indicated at 10 and 12 are against the inside central portion of the seal blank or closely adjacent thereto, and at this time the loop formed by the strappinglO and,12 is very loose about the bundle to be bound. The ends of the folding jaws indicated at are comparatively sharp and engage the outer face of the seal wings at positions slightly outwardly beyond thegrooves 22. Ordinarily where there are several sets of. folding jaws which operate together in side by side relationship with notching jaws spaced between them onlyv some of these sets .(the central set in the present instance) need to have the sharp tips or ends-as indicated at 30, the others having more rounded ends as indicated at 32. In any event, it is not necessary to provide any of the jaw ends with lips of the type previously mentioned as being customary.

When the folding jaws swing inwardly about the pivoting axes 28 to the position indicated in Fig. 4, it will be seen that not only do they have an inward component but also a downward or backward component toward the chair 24 inasmuch as the pivoting axes 28 are located at positions outwardly of the ends 30 of the jaws. upon slight inward and downward movement of the jaws 26 the noses 30 thereof will snap into the grooves 22 as indicated in Fig. 4. From this'it will be seen that the length and positioning of the grooves 21. in a particular seal will depcnd 'upon the width and number of sets of Therefore,

folding jaws having sharp ends which are employed in the tool with which the seal is to be used. Continued inward and downward movement of the folding jaws therefore exerts a downward or backward force against the wings 18, tending to urge the seal blank downwardly or backwardly against the chair 24. This causes a downward bending of the two edges of the central portion 16 of the seal blank so as to bend the edge portions indicated at 34 away from the edges of the adjacent strap layer 12. Soon thereafter, with continjied inward and downward movement of the folding jaws 26, the sharp noses 30 slide or rock out of the grooves 22, as indicated in Fig. 5, and at this portion of the cycle are producing a downward and inward action against the wings of the seal but are free to slide laterally over the outer surfaces of these wings. As this action continues, so as to bring the inner faces of the wings against the top layer of the strapping as indicated in Fig. 6, the formerly downwardly bent edges of the central portion indicated at 34 are bent upwardly or forwardly again into contact with the adjacent face of the strap layer 12. The completely folded seal, therefore, appears as indicated in Fig. 6, where it will be seen that the two layers of the strapping are closely embraced between the central portion of the seal blank and the two wings and that the fold of the seal at the two edges of the strapping does not quite touch the strapping edges. One layer of the strapping, therefore, can be moved longitudinally at high speed in order to shrink the loop about the handle to be bound and to apply a proper tension to the strapping, after which the seal and strap edges may be notched in a conventional manner.

From the above it will be seen that the principal feature of the present invention is the provision of the grooves 22 to be caught by the noses of the folding jaws so as to exert a strong downward component upon the it will be apparent that modifications and variations theretip, pivotally mounted folding and sealing jaws for forming a joint between overlapping portions of metallic strapping, said blank having a fiat rectangular central portion with a width slightly greater than the width of the strapping-with which the blank is to be used, and a pair of rectangular wings joined by rounded corners to said central portion along its side edges and extending diagonally outwardly therefrom, characterized by:the fact that each of said wings is formed with ashallow, stock thinning groove on its inside surface extending substantially the length of said wing parallel to the adjacent side edge of said central portion andgspaced from the adjacent edge of said central portion a distance slightly greater than two thicknesses of the strapping rnaterial with which the seal blank is togbe used, each of said wings adjace t the free edge thereof is formed with a jaw tip engaging groove on the external surface thereof, extendipg parallel to said free edge, and the inside and external eurfaces of said wings except for said grooves are substanly smooth to perm nes n o a plura ity o s al blanks and the sliding of adjacent nested seal blanks relative to each other, whereby when said wings are folded about the overlapping strapping portions the sharp jaw tips temporarily engage in said external surface grooves to impart a backward movement component to the inward folding movement of said wings to insure that the latter are properly folded about the strapping portions without binding the edges of the strapping portions between the central portion and the folded wings of the seal blank.

References Cited in the file of this patent UNITED STATES PATENTS Birkenmaier Apr. 12, 1932 Birkenmaier et a1 Nov. 27, 1934 Childress Feb. 18, 1941 Reiter Mar. 11, 1941 Crosby June 14, 1955 FOREIGN PATENTS Great Britain Jan. 27, 1941 Great Britain May 16, 1951

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