GB2024302A - Staple for use with a hasp - Google Patents

Abstract

A staple for use with a hasp comprises a sheet metal base 10 and a U-shaped wire element 18 with outwardly turned lugs 20 at the ends of its legs and bridge portions 22 of the base 10 embrace the lugs 20 to constrain the element 18, but allow it to pivot relative to base 10; a slot (14) in base 10 narrower than the thickness of element 18 holds element 18 captive to base 10. Manufacture of the staple is illustrated in Figures 5, 6. To secure the element 18 to base 10 (see Figure 6) the base is formed with an I-shaped slot (24) and a punch 44 presses the base 10 over element 18 to form bridge portions 22 and to narrow the slot. <IMAGE>

Description

SPECIFICATION Staple This invention relates to staples for use with hasps.

A typical staple incorporates a piece of U shaped wire riveted under a plate to a member which secures both ends of the 'U'. These staples thus involve a high material cost and the cost of several different manufacturing operations. It is an object of the present invention to provide a staple improved in one or both of these respects.

The present invention provides, according to one aspect, a staple comprising a base and a generally U shaped element having its legs provided at their ends with outwardly turned lugs, the base having integral aligned bridge portions which embrace the lugs to constrain the U shaped element with respect to the base but do not tightly frictionally engage the lugs so that the U shaped element is free to pivot with respect to the base, the base further having a portion or portions lying between said bridge portions to prevent the legs of the U shaped element from moving towards each other thereby to hold the U shaped element captive with respect to the base.

Preferably the base is of sheet metal and the U shaped element of wire.

According to another aspect of the invention there is provided a method of manufacturing a staple, comprising the steps of: forming a base with two flat bridge portions and a slot therebetween, forming a U-shaped element with outwardly extending lugs on the free ends of the legs thereof, placing the base over the U-shaped element so that the latter extends through the slot with the lugs abutting the bridge portions, and deforming the base so that the bridge portions thereof embrace the lugs whilst the slot is narrowed to prevent the legs of the U-shaped element from moving towards one another, thereby to hold the U-shaped element captive with respect to the base.

Preferably a succession of U-shaped elements with outwardly extending lugs on their legs are formed out of a continuous length of wire.

Preferably a succession of bases are formed in a series of operations out of a continuous strip of sheet metal, the slot in each base being 'I' shaped and centrally positioned in the base.

When such a base and U shaped element are assembled, the deformation of the bridge portion reduces the width of the I shaped slot from the original width, in a direction perpendicular to the stem of the '1', and thus provides a retaining portion of the base which prevents the said movement of the legs of the U-shaped element.

The invention will now be described by way of example only with reference to the accompanying drawings in which: FIGURE 1 is a perspective view of a staple according to the invention.

FIGURE 2 is a front elevation of the staple FIGURE 3 is a side elevation of the staple FIGURE 4 is a plan view of the staple FIGURE 5 is a diagrammatic representation of successive stages in the manufacture of a base of the staple FIGURE 6 illustrates the formation of U-shaped elements and the assembly of staples Referring firstly to Figures 1 to 4, there is shown a staple comprising a base 10 and a generally U-shaped element 18. The base 10 has a plurality of circular countersunk holes 12 for receiving screws for attaching the staple to, for example, a door.

The U-shaped element 18 has outwardly extending lugs 20 on the free ends of its legs. The base 10 has two bridge portions 22 which embrace the lugs 20 of the U-shaped element 18 and a slot 14 which is narrower than the thickness of the U-shaped element. Because the slot 14 is narrow, the legs of the U-shaped element 18 cannot be moved towards one another, and thus the U-shaped element 18 cannot be detached from the base 10.

The bridge portions 22 do not tightly embrace the lugs 20, so that the U-shaped element is capable of limited pivotal movement relative to the base 10.

Prior to assembly of the staple, the base 10 is of flat form and has a relatively wide centrally positioned 'I' shaped slot. During assembly of the staple, the base 10 is bent around the lugs 20 of the U-shaped element 18 to form the bridge portions 22, using the lugs 20 as formers or dies for such bending of the base. During this operation, the central part of the 'I' shaped slot is narrowed to form the relatively narrow slot 14 so that the U-shaped element is held captive to the base 10. When this condition has been reached, the U-shaped element is free, in addition to its pivoting movement, to move over a limited distance in a direction perpendicular to the base being constrained in one direction by the bridge portions 22 and in the opposite direction by contact of the U-shaped element with the base 5 adjacent to the slot 14.

Successive stages of manufacture of the base 10 are illustrated in Figure 5. In this, a continuous strip of sheet metal 30 is fed from a bulk supply thereof through a number of work stations. At the first station, holes 12 for receiving fixing screws are pierced, and at the third station the holes are cou ntersunk, the second station being an idling position. At the fourth station a slot 16 is pierced, and at the fifth station two further slots 32 are pierced to form an 'I' shaped slot 24. At the sixth station, the completed base 10 is cut from the strip of sheet metal advancing through the previous work stations.

Referring now to Figure 6 of the drawings, wire is fed as a continuous length 36 through, if necessary, a straightening die (not shown) to a first form die 38.

This gives a U-shaped bend 40 to the wire 36. There is then an idling position.

The wire 36 is then fed onto a second form die 42.

The base 10 is fed in a direction at right angles to that of the wire 36 and at station 6 (Figure 5) is positioned over the U-shaped bend 40. A punch 44 then crops the base 10 from the remainder of the metal strip, causes the base to fall over the U-shaped bend 40, and subsequently presses the base over the wire to form bridge portions 22 which embrace the parts of the wire adjacent the U-shaped bend. During this operation, the portion 16 of the 'I' shaped groove in the base is narrowed so that the wire element is retained against removal from the base. During this operation, the wire itself acts as a former to co operate with the punch 44 to produce the bridge por tions in the base.

The wire, now united with the base, is advanced to the next work position at which the formed staple (46) is separated from the next following staple by cropping the wire along the line shown at 48. The manufacture of the staple is now complete.

Although a particular sequence of operations in forming the base has been described above, it will be appreciated that this need not be closely adhered to. For example, the I' shaped slot in the base could be formed before the holes for receiving fastening screws. Further, it would even be possible for these holes to be formed after the base has been united with the wire element of the staple, or simultaneouslywith such assembly.

Claims (8)

1. A staple comprising a base and a generally U-shaped element having its legs provided at their ends with outwardly turned lugs, the base having integral aligned bridge portions which embrace the lugs to constrain the U-shaped element with respect to the base but do not tightly frictionally engage the lugs so that the U-shaped element is free to pivot with respect to the base, the base further having a portion or portions lying between said bridge portions to prevent the legs of the U-shaped element from moving towards each other thereby to hold the U-shaped element captive with respect to the base.

2. A staple according to Claim 1 wherein the base is of sheet metal, and the U-shaped element of metal wire.

3. A method of manufacturing a staple, comprising the steps of: forming a base with two flat bridge portions and a slot therebetween, forming a U-shaped element with outwardly extending lugs on the free ends of the legs thereof, placing the base over the U-shaped element so that the latter extends through the slot with the lugs abutting the bridge portions, and deforming the base so that the bridge portions thereof embrace the lugs whilst the slot is narrowed to prevent the legs of the U-shaped element from moving towards one another, thereby to hold the U-shaped element captive with respect to the base.

4. A method according to Claim 3 wherein a succession of U-shaped elements with outwardly extending lugs on their legs are formed from a continuous length of wire.

5. A method according to Claim 3 or Claim 4 wherein a succession of bases are formed in a series of operations from a continuous strip of sheet metal.

6. A method according to Claim 5 wherein the slot in each base is 'I' shaped and centrally positioned in the base.

7. A staple substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

8. A method of making a staple, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.