Self-Locking Band

My present invention relates to a self-locking band, or single-use tie, serving as a seal for a package, a holder for a price tag or a similar device designed to prevent unauthorized detachment of certain items from associated articles.

Such self-locking bands generally comprise a flexible link terminating in a male extremity or tongue and in an opposite female extremity or socket into which the tongue can be matingly inserted, the socket being provided with internal formations which prevent a withdrawal of the inserted tongue. Thus, a loop formed by the interengaging male and female extremities cannot be opened except by forcible rupture.

In my prior Italian Pat. No. 924,832 there has been disclosed a band of this description whose tongue consists of stiff plastic material engageable by elastically deformable barbs in the associated socket. While such a band is well suited for its intended purpose, it has the drawback of allowing only one mode of interfitting of the two extremities. Instances arise, however, in which it would be convenient for a user to have alternative ways of aligning the two extremities with each other prior to closure of the loop, on account of the peculiar configuration of the article to be tied.

The object of my present invention, therefore, is to provide an improved band of the character set forth which offers such alternative modes of interfitting.

In accordance with my present invention, the female extremity of the link is a sleeve with two open ends internally provided with oppositely facing resilient barbs which are positioned to coact with the male extremity and prevent its withdrawal upon insertion thereof through either of these ends.

In such a band the end of the link remote from the male extremity is advantageously fastened to the sleeve at a point midway between the open ends of the latter, thus forming with it a T-junction which allows the ends of the link to approach each other at right angles rather than in an aligned position. This permits the use of shorter links in forming a loop around a given article since the link need no longer be stretched into such a position of alignment. Moreover, the user has a choice of closing the loop on one or the other side of the "T". Furthermore, the link may be a relatively stiff stem of elastomeric material, e.g. polyethylene or polypropylene, inasmuch as it need not be bent through a full 360.degree.; such a stem will therefore be less liable to accidental destruction.

The above and other features of my invention will now be described in detail with reference to the accompanying drawing in which:

FIG. 1 is a side view of an improved self-locking band according to my invention;

FIG. 2 is a cross-sectional view taken on the line II -- II of FIG. 1;

FIG. 3 is a top view of the band shown in FIG. 1;

FIG. 4 is a perspective view of the band in a position of incipient loop closure; and

FIG. 5 is a cross-sectional view of the interlocked extremities of the band .

The self-locking band shown in the drawing comprises a round stem of elastomeric material terminating in a male extremity or tongue 2 and a female extremity or socket 3 integral therewith. Socket 3 has a body 4 in the shape of a sleeve of rectangular cross-section with opposite open ends 5 and 5'; between these ends, along the minor sides of the rectangle, I provide two symmetrical internal projections 6, 6' of dovetail shape forming two pairs of barbs respectively pointing toward ends 5 and 5'.

Extremity 2 is a flat tonge with an arrowhead 7 whose hooks or prongs 9 and 9' include with its shank 8 an acute angle .alpha. identical with the angles included between the flanks of dovetails 6, 6' and the walls of sleeve 4. The resiliency of these prongs and of the coacting barbs allows the interlocking of arrowhead 7 with dovetails 6 and 6', regardless of its direction of insertion, as illustrated in FIG. 5. Upon such insertion, an abutment consisting of two shoulders 10 and 10' at the rear of tongue 2 comes to rest against the end of the sleeve through which the tongue has been introduced, thereby blocking the interior of the sleeve so as to prevent any tampering with the connection from that side. At its opposite end, access to the coacting formations 6, 6' and 9, 9' is blocked by the shape of the arrowhead whose height and width are close to the corresponding dimensions of the interior of the sleeve.

A square block 11, separated from abutment 10, 10' by a reinforced stem portion 1' of square profile, serves as a handle in manipulating the tongue 2.

A longitudinal slot 12, extending from near the tip of arrowhead 7 to the vicinity of shoulders 10 and 10', reduces the weight and increases the flexibility of the tongue for easier interfitting. The length M of the tongue, from its tip to the abutment 10, 10', substantially equals that of the sleeve 4 as seen in FIGS. 2 and 3; on the other hand, the combined height M' of shoulders 10 and 10' exceeds the internal height N of the sleeve and substantially equals its external height. The distance of prongs 9 and 9' from shoulders 10 and 10' corresponds approximately to the spacing of either pair of flanks of dovetails 6 and 6' from the remote end of the sleeve. As seen in FIG. 4, the width of shoulders 10 and 10' is about the same as that of the sleeve.

FIG. 4 clearly shows, in full lines, the insertion of tongue 2 into the end 5 of socket 3 and in dashed lines the alternative introduction of the tongue into end 5'. Naturally, once a choice has been made, the tongue will retain its selected position within the socket until the loop is forcibly broken, thereby preventing the reuse of the tie and evidencing its disengagement from the article to which it was originally attached.

The band 1, 2, 3 can be molded in one piece, though the tongue 2 may be given its final shape by stamping.