Flexible locking tie

Abstract

 A flexible tie for bundling electric cables or the like has a flexible strap (4) formed with transverse teeth that is releasably gripped in an aperture in a tie head (1). A transverse inner surface of the head aperture is provided with a tooth (9) that engages between teeth on the strap. A pivoted lever (2) can be moved manually from a locking position in which it holds the teeth on the strap in engagement with the tooth on the head to a position in which it allows the toothed strap to move freely through the head.

Description

[0001] This invention relates to flexible plastics ties, suitable for securing and supporting electric cables and other elongate articles, of the kind in which a flexible strap formed with transverse teeth can be releasably gripped in a tie head formed with an aperture through which the strap can be passed.

[0002] The invention is applicable both to single piece ties, in which the head is integral with the toothed strap, and to multi-piece ties in which the head and toothed strap are separate.

[0003] Single piece ties are suitable for wrapping around and securing together a bundle of cables, with the toothed strap passing from the head, around the bundle, and back through the head in which it is locked by engagement of the transverse tooth with a part of the head.

[0004] Two piece ties are suitable for attaching a cable, or a bundle of cables, to a support, such as a cable tray; the head will normally be mounted on the free end of a plain flexible strap, attached at its other end to the support, and the toothed strap will be attached at one end to the support with its free end available for passing through and locking to the head. Other configurations of tie head and toothed tie strap are possible.

[0005] In accordance with the invention, a transverse inner surface of the head aperture is provided with a tooth, adapted to engage between teeth on the toothed strap, and a pivoted lever, mounted within the head, is adapted when in a locking position to hold the teeth on the strap in engagement with the tooth on the head and is adapted to be moved manually from the locking position to a position in which it allows the toothed strap to move freely through the.head.

[0006] The lever preferably pivots about a pair of lugs protruding from opposed parallel inner surfaces of the aperture, which surfaces are at right angles to the tooth on the head. The lugs are preferably integral both with the head and the lever, so that the head, lugs and lever can be formed as a single moulding. When there is no torsional stress in the lugs, (that is in the position as moulded) the spacing between the lever and tooth is less than the thickness of the strap. Thus the lever is always under a biassing torque when the strap extends through the head.

[0007] Preferably the head has a U-shaped cross-section joined at its base to the strap and lying parallel to the plane of the strap when flat, with the tooth formed on the inner surface of the base.

[0008] In an alternative form of strap, this arrangement is modified by providing a further wall bridging the limbs of the U-shapa, so that the head takes the form of a short tube of rectangular cross-section.

[0009] The surface(s) of the lever adapted to bear against the plain surface of the toothed strap is or are preferably arcuate with a radius of curvature considerably greater than the shortest distance of the lever surface(s) from the pivotal axis of the lever.

[0010] In order that the invention may more readily be understood, a description is now given, by way of example only, reference being made to the accompanying drawings in which:-

Figure 1 is a top view of the head of a tie embodying the present invention;

Figure 2 is a view in the direction of arrows 2-2 in Figure 1;

Figure 3 is a view in the direction of arrows 3-3 in Figure 1 of a head and strap in locked position; and

Figure 4 is a side view, partly in section, of another tie embodying the present invention.

[0011] The tie shown in Figures 1 to 3 has a head 1 of U-shaped cross-section, the head being moulded integrally with a lever 2 and a strap 3 which, for one piece ties, is the plain end of a toothed strap 4 and for multi-piece ties is separate from toothed strap 4. Head 1 supports lever 2 by lugs 5 which permit the lever to pivot about axis 6.

[0012] The lever has two arcuate surfaces 7 bearing on the strap, and generated about an axis 8 so that the radius of curvature of each surface is considerably greater than the shortest distance of the face from the pivoted axis of the lever. The lever is shown in the locking position in which strap 4 engages with a transverse tooth 9 on the inside of the base of the U-shaped head 1.

[0013] When lever 2 is in its moulding position, i.e. there is no torsional stress in the lugs, the minimum spacing between surface 7 and tooth 9 is less than the thickness of strap 4, typical volumes being 0.7 mm and 1 mm respectively. Thus in the locking position, lever 2 is continually biassed towards the strap 4 and urges it against tooth 9.

[0014] Axis 8 is located beyond the rear of lever 2 (to the left of lever 2 in Figure 3) so that the torque exerted by tension in the strap 4 on the lower portion of surfaces 7 is greater than that exerted on the upper portion, thereby further urging strap 4 against tooth 9.

[0015] Hand pressure on an arm 10 of the lever, to cause it to rotate anti-clockwise, as shown in the drawings, with simultaneous tension on the strap 4, urging it in the direction R (Figure 3), will release the strap from engagement with tooth 9.

[0016] Roughened surfaces 11 and 12 are provided on the arm 10 and bottom of lever 2 respectively to enable lever 2 to be gripped securely between the finger and thumb of an operator during pivoting of the lever.

[0017] The tie illustrated in Figure 4 has parts corresponding to those of the tie of Figures 1 to 3, except that head 13 has a rectangular cross-section incorporating an additional cross-member 14, and lever 2 has a single arcuate surface 7 which bears on strap 4.

[0018] In the illustrated ties the head, the lever, and the strap can be simultaneously moulded in a two piece mould without retracting parts. A suitable material is nylon.

Claims

1. A flexible tie having a flexible strap formed with transverse teeth to be releasably gripped in a tie head formed with an aperture through which the strap can be passed, is characterised in that a transverse inner surface of the head aperture is provided with a tooth, adapted to engage between teeth on the toothed strap, and a pivoted lever, mounted within the head, is adapted when in a locking position to hold the teeth on the strap in engagement with the tooth on the head and is adapted to be moved manually from the locking position in which it allows the toothed strap to move freely through the head.

2. A tie according to Claim 1, characterised in that the lever connects with the head by and is pivotable about a pair of lugs protruding from opposed parallel inner surfaces of the aperture, which surfaces are at right angles to the tooth on the head.

3. A tie according to Claim 1 or Claim 2, characterised in that the lever is formed integrally with the head.

4. A tie according to any one of Claims 1 to 3, characterised in that the head has a U-shaped cross-section joined at its base to the strap and lying parallel to the plane of the strap when flat, with the tooth formed on the inner surface of the base.

5. A tie according to any one of the preoeding Claims, characterised in that the head is in the form of a short tube of rectangular csoss-section.

6. A tie acoording to any one of the preceding Claims, characterised in that at least one arcuate surface of the lever is adapted to bear against the plain surface of the toothed strap and has a radius of curvature considerably greater than the shortest distance of that lever surface from the pivotal axis of the lever.

Drawing