The use of cable ties to bundle a plurality of wires, cables or similar objects has long been known. Many of the cable ties presently available include a cable tie strap body having a head integrally formed at one end and a tail at the other end. The head includes an aperture therein through which the tail may be inserted. A locking device in the head securely locks the tail within the head upon looping the strap about a bundle of wires or other objects. Examples of such cable ties are shown in U.S. Pat. Nos. 3,739,430 and 3,872,547.
Other types of cables ties which are also available include assemblies where the cable tie head is formed separately from an elongate strap body. These cable ties include locking devices supported within the head which are capable of engaging opposite ends of the strap body when the strap body is looped about a bundle of wires. Such two-piece construction allows the use of a long length of strap thus permitting the cable tie assembly to be used to secure a bundle of wires having a large diameter.
With respect to the two-component design since the cable tie head must include a locking device which securely locks both ends of the strap, various dual locking devices have been developed so as to secure the ends of the strap within the head. One such cable tie is shown in U.S. Pat. No. 4,498,507 where a single barb is employed in the head. The barb has one end which is separated in a fork-type configuration so that one end of the fork engages one end of the strap while the other end of the fork engages the other end of the strap inserted in the head.
Other two-component cable tie assemblies where the head is separate from the strap employ a strap locking device in the form of a metal barb which is embedded in the cable tie head. The metal barb in these designs are formed into generally a V-shaped cross-sectional configuration. One leg of the V extends in one direction to engage one end of the strap inserted through the head and the other leg of the V extends in an opposite direction to engage the other end of the strap once it has been secured about a bundle of wires. Examples of such cable tie constructions having V-shaped metallic locking barbs are shown in U.S. Pat. Nos. 4,422,217; 4,993,669; 5,102,075 and 5,544,391.
However, in each of these designs a single locking barb is used to lock both ends of the cable tie strap inserted through the head. While these designs adequately lock the cable strap in the head, since the barb is an integrally formed single member, the insertion forces required to insert the strap into the head and to deflect the barb are extremely high. This is due in part because of the integral construction of the barb and the necessity for the entire barb to deflect. It is especially difficult to insert the second end of the strap, after the first end has been inserted, as the entire barb has been deflected by insertion of the first strap end.
The art has seen attempts to reduce the insertion force necessary to insert both ends of the strap into a cable tie head by employing metallic barbs of two-piece construction. Such metallic barbs are separately secured within the cable tie head and may be supported on flexible platforms or hinges so as to permit easy deflection of the barb upon insertion of the strap into the head. Examples of such two-piece barb constructions are shown in U.S. Pat. Nos. 5,121,524 and 5,193,251.
While each of these separate barb designs serve adequately for their intended purposes, it has been found that in certain applications and under extreme environmental conditions, the plastic support for the metal barbs may not be as reliable as may be required.
It is therefore desirable to provide a two-component cable tie assembly which includes a head and a separate strap which secures both ends of the strap within the head upon looping the strap about a bundle of wires. Further the ends of the strap are to be securely retained within the head and provide for low insertion force of the strap into the head.