US2142782A - Staple - Google Patents

Description

Jan. 3, 1939. E. c. GILLETTE 2,142,782

STAPLE Filed Sept. 15, 1938 Fiai ra 12 Fiat; FiG.6 5 n 5" 8 a ELMO/V C 0/1.;57'75 INVENTOR.

BY Wu [2 WW ATTORNEY.

Patented Jan. 3, 1939 PATENT, OFFICE STAPLE Elmon C. Gillette, New York, N. Y.

Application September 15, 1938, Serial No. 230,005

1 Claim.

My invention relates to staples and has particular reference to staples for stapling cardboard boxes.

The object of my invention is to provide a staple which can be used for stapling cardboard boxes by a novel method for which ordinary or known staples are not suitable. This novel method has been developed specially for stapling covers of cardboard boxes when the boxes are already filled with merchandise. The merchandise cannot be relied upon to furnish sufficient stiff backing as is required for ordinary stapling machines in which the ends of the staples are bent against rigidly supported anvils under the work being stapled. At the same time, the merchandise may be damaged if the staple or stapling device penetrates to an appreciable depth below the lower surface of the covers. In order to satisfactorily staple the box covers under such conditions, the staple and the stapling device must fulfill the following requirements:

l. The staple must be of such a shape that it should readily penetrate all the boards of the cover which are being stapled together, even if the boards are lightly supported by the merchandlse and may yield if a great pressure is required for the insertion of the staple. The only staple that will answer this requirement is a U-shaped staple having straight parallel legs. Such a staple will require the least support for the penetration of the first as well as of the other successive layers of cardboard. It should be noted that a staple with curved legs will not answer this requirement for the reason that such legs, moving in an arcuate path, will enter the second and other layers at a reduced angle to the surface of the board. v

Assuming that the resistance to penetration of the board is the same for the second layer as for the first, it follows that a lesser component of the total force applied to the staple will be available for penetration in the angular direction of movement of the point of the staple, and a correspondingly greater portion of the force will be directed at right angles to the surface of the second layer at the point of the staple, the only effect of this component being to push the second layer away from the first. In order to efiect the penetration, the total force must be increased so that the angular component must be equal to the originally applied force for the first layer. A correspondingly greater resistance will be required from the merchandise for retaining the second layer in contact with the first and for the proper penetration of the layers by the staple. The greatest force is usually required for the penetration of the outer sheet of paper of the board since the majority of paper boxes are made of corrugated board which has corrugated sheets of paper inside of a relatively low resistance to penetration by the staple, and strong outer sheets of paper having relatively greater resistance to penetration. It is quite important, therefore, that at least the upper sheet of the second board be penetrated by the straight parallel legs of the staple.

2. The ends of the staple legs should not be allowed to extend appreciably below the under surface of the inner or lower board as otherwise the staple may damage the merchandise in the box. With the type of stapling apparatus, therefore, employing jaws which penetrate the board together with the staple and curve the ends of the staple by rotating around them, it is necessary to start their rotation soon after the staple has penetrated through the upper sheet of the lower board but before the lower sheet is penetrated.

The ends of the staple then pierce the lower sheet of the under board at an acute angle, hugging the under surface of the board, being. therefore, unable to pierce the merchandise. The board, however, will not be pushed away, being held by the curved jaws. The foregoing requirements determine the design of the staple for use with the stapling machine employing stapling jaws which insert the staple and clinch its ends around the board by rotating with the legs of the staple.

My invention has for its object, therefore, to provide a staple with straight parallel legs. The bridge of the staple connecting the legs must preferably have a depressed portion, coming to rest against the upper board when the ends of the legs pierce the upper sheet or layer of the under board but before they pass through its lower sheet or layer. I

Another object of my invention is to provide raised portions at the corners of the staple so that upper portions of the legs will extend above the board and will be forced into the board when the staple is forced all the way in so as to flatten the bridge against the upper board, the final insertion being accompanied by the rotation of the jaws for clinching the staple.

A novel'result is, therefore, obtained by combining the two foregoing features, i. e. easy penetration of the boards by the parallel legs of the staple up to a point inside the lower board as determined by the length of the legs below the pass through the boards, and the curved staples cannot penetrate through the lower board unless a rigid backing is provided under the latter and unless the force required for such penetration is substantially increased. At the same time, none of the known types of staples can be used with a machine employing two steps in the stapling process: first, straight penetration, and second curving the ends and clinching them around the under board.

In order to facilitate the insertion of the staple still further and to reduce the pressure on the board, one leg of the staple may be made shorter than the other. This is especially important for stapling corrugated boards because such boards,

' as it has already been explained, have relatively hard outer sides and relatively soft inner corrugated sheets so that the principal resistance to penetration occurs at the moment of piercing the sides of the board. By making one leg of the staple shorter than the other, the resistance is reduced almost by one half since one leg fully passes through the side of the board before the other leg begins to touch its surface.

For stapling boards made of a relatively weak paper, it is desirable to flatten the depressed portion of the staple bridge, the corner portions rising more or less steeply from the ends of the flat portion. The flat portion provides a larger surface through which pressure is applied to the board so that there is less danger of damaging this surface. The same result can be also accomplished by forming the bridge in the shape of an inverted arc of a relatively large radius.

Such a shape has an added advantage that there are no corners in the middle of the bridge to be straightened out and which may leave marks on the bridge upon completion of the stapling operation.

My invention is more fully described in the accompanying specification and drawing in which:

Fig. 1 is a side view of my staple when fully inserted into boards and prior to the staple being bent by the jaws of a stapling machine.

Fig. 2 is a view of the staple when fully clinched around the boards.

Fig. 3 is a view of a modified staple.

Fig. 4 is a similar view of still another modi fication.

Fig. 5 is a. view of another modification.

Fig. 6 is an end view of the staple.

Figs. 7 and 8 are views of modified staples having one leg longer than the other.

My staple consists of a piece of a flat wir having substantially parallel spaced straight legs i and 2 which may be sharpened at the ends to facilitate their penetration into boards 3 shown in dotted lines. One leg may be made shorter as shown, which also facilitates the penetration, one leg at a time being forced through the outer paper layers of the cardboard, especially of the corrugated type. The upper side of the staple is inwardly recessed at 4, corner portions 5 being raised thereby providing an excess of the length of material in the raised portion to be forced into the board when the jaws 6 of the stapling machine begin to rotate for curving the ends of the staple around the under board. The raised portions 5 are then pressed flat by the heel portion I of the jaws, the jaws being placed side by side, being of about half of the width of the staple.

The middle portion 4 is preferably made flat so that it can rest on the top surface of the boards when penetration is completed, and the total length of the middle flat portion 4 and of the upper sides of the raised portions 5 is substantially equal to the distance between the Jaws so that the upper side of the staple in its flattened form as shown in Fig. 2 fills the space between the inner sides of the jaws. This can be accomplished by giving the outer sides 8 of the raised portions 5 a curvature corresponding to the radius of curvature of the jaws on the inside. The same object can be attained by extending the upper sides of the raised portions 9 (Fig. 4) to the central point III of the upper side of the staple, provided the line 5i05 is equal to the inside'distance between the jaws. The staple of Fig. 1 may be modified by providing a concave bridge portion II as shown in Fig. 5.

The flattened middle portion 4 of the bridge is essential when the staple is used with jaws 6 having a wide rear or heel portion 1 which forms an effective barrier for retaining other staples in their magazine (not shown) in the stapling machine when the jaws are in the closed position shown in Fig. 2. The length of the flat portion 4 is preferably made equal to about one half of. the difference between the legs.

The provision of making one leg of the staple shorter than the other is also applicable to ordinary staples having straight upper sides I! as shown in Fig. 3. Such a staple has an advantage in considerably reducing the force of penetration when it is used with boards 3 having side paper layers of a relatively high resistance to penetration and inner corrugations of a relatively low resistance, or when it is used for stapling several thicknesses of paper l3, Fig. 3. The width of the staple is shown in Fig. 6. The jaws of the stapling machine are of about half this width, being placed side by side against the staple and in staggered relation to each other.

The centers of rotation of the jaws 6 are spaced apart as shown so that the centers of the arcs 8 may be also correspondingly spaced.

The legs, while being of different-length, may be even at the ends as shown in Figs, 7 and 8, the upper portions or corners being at different heights. The Jaws are made of the same shape as for ordinary staples so that the higher corner is pressed down first causing one leg to penetrate the paper while the pressure is relieved from the other leg. The upper portion of the staple becomes straightened as soon as the longer staple end penetrates the paper. This arrangement has an advantage in that both legs are placed on the board before the pressure is applied.

It is understood that other similar modifications may be provided for my staple within the scope of the appended claim.

I claim as my invention:

A staple made of a strip of metal of a uniform width so bent as to form straight parallel legs with a bridge therebetween,'the bridge being inwardly depressed to a substantial depth in the shape of an inverted arc-like curve, the ends of the arc-like bridge being bent downward and outward to meet the upper portions of the legs, the length of the arc-like portion of the strip being approximately equal to the distance between the legs.

ELMON C. GILLETTE.

Images