EP0893360A1

EP0893360A1 - Plastics tie having release mechanism

Info

Publication number: EP0893360A1
Application number: EP98305710A
Authority: EP
Inventors: Steven John Blanks
Original assignee: Bowthorpe PLC
Current assignee: Bowthorpe PLC
Priority date: 1997-07-21
Filing date: 1998-07-17
Publication date: 1999-01-27
Also published as: GB2327455A; GB2327455B; GB9715301D0

Abstract

A one-piece moulded plastics tie comprises an elongate strap 40 provided with head 41 at one end and with a series of ratchet serrations on one side thereof, a pawl 46 in the head for engaging the strap serrations when the strap 40 is passed through a passage 44 in the head and a pair of levers 47 arranged on opposite sides of the head 41 for increasing the height of the passage 44, in order to release the strap 40 from the pawl 46.

Description

This invention relates to a plastics tie for tying cables and other objects.

Plastics ties for tying cables and other objects are well known. Typically these so-called cable ties comprise an elongate serrated strap having a head at one end thereof. In use, the strap is looped around the object to be tied and inserted through a passage in the head and pulled tight. A pawl element in the passage interlocks with the strap serrations to prevent loosening of the tie.

It has been proposed to provide a releasable tie which comprises a pawl having a tab disposed thereon, projecting from the passage. The pawl can be disengaged from the strap serrations by pulling the tab back, so that the tie can be loosened.

In the as-moulded condition of known ties, the pawl projects into the passage. However, the pawl is free to move back towards its supporting wall as the strap is inserted. The pawl moves back against a resilient bias, which is inherently provided by the plastics material. The degree of this resilient bias depends on the thickness of the pawl at its flexure point. In practice the bias force should be as low as possible, in order that the strap can be inserted easily.

A disadvantage of providing a release tab on a low insertion force tie is that permanent plastics deformation can occur if the tie is released too often or with too much force. Accordingly, when this happens the pawl will no longer be biased into engagement with the strap when the tab is released.

We have now devised a plastics tie which alleviates the above-mentioned problem.

In accordance with this invention there is provided a moulded plastics tie comprising an elongate strap provided with head at one end and with a series of ratchet serrations on one side thereof, a pawl in the head for displacing a portion of the head, opposite the pawl, in order to release the strap from the pawl.

The release mechanism does not rely on bending back the pawl and thus the tie does not suffer from the problems of plastic deformation of the pawl.

Preferably the displacing means is arranged to increase the height of the passage, between a floor and roof thereof, from the height of the passage in the as-moulded condition of the tie.

Thus, when the release means is actuated, the height of the passage increases sufficiently for the strap to disengage from the pawl, thereby allowing the tie to be loosened.

Preferably the tie comprises a one-piece moulding of plastics material, the release means being deformable from its as-moulded condition to cause the height of the passage to increase, the deformable portion of the release means being greater in cross-sectional area than a flexure point of the pawl, so that the deformable portion of the release means is less susceptible to plastics deformation than the pawl.

In one embodiment, the roof of the passage comprises a wall that can be moved to increase the height of the passage.

The roof and floor are preferably interconnected by respective side walls extending on opposite sides of the passage, one of the side walls comprising a pivot and the opposite side wall comprising a lock, which can be released to disconnect the roof from the floor along one side of the passage, the pivot enabling the roof to move away from the floor of the passage when the lock is released.

Another disadvantage of known releasable ties is that it is difficult for divers and other persons wearing gloves to readily release them.

In order to overcome this problem, the head preferably comprises a projection that extends outwardly in respective opposite lateral directions with respect to the passage, the projection forming a laterally compressible head portion, which can be compressed to increase the height of the passage. It is thus relatively easy for someone wearing gloves to compress the head in order to release the tie.

In one embodiment the roof and floor of the passage are interconnected by resiliently flexible side walls which extend outwardly in respective opposite lateral directions intermediate their opposite ends, and which define said laterally compressible head portion.

In an alternative embodiment, the roof of the passage comprises a pair of side-by-side formations disposed on respective arms that extend forwardly from a body portion of the head to define respective opposite side walls of the passage, the arms being connected to respective levers that extend laterally outwardly with respect to the passage, in a rearward direction. When the levers are squeezed together, the formations move away from the floor of the passage on the body, thereby releasing the strap from the pawl.

Preferably the levers are connected to the body of the head by flexible webs which help prevent plastic deformation of the tie release mechanism.

The pawl may extend from the roof or floor of the passage. However, the pawl preferably extends from a portion of the head to which the strap is attached, in order to increase the strength of the tie.

Embodiments of this invention will now be described by way of examples only and with reference to the accompanying drawings, in which:

FIGURE 1 is a plan view of a first embodiment of plastics tie in accordance with this invention;

FIGURE 2 is a perspective view of a second embodiment of plastics tie in accordance with this invention;

FIGURE 3 is a plan view of the tie of Figure 2, when fastened;

FIGURE 4 is a plan view of the tie of Figure 3, when released;

FIGURE 5 is a perspective view of a third embodiment of plastics tie in accordance with this invention;

FIGURE 6 is a plan view of the tie of Figure 5, when fastened;

FIGURE 7 is a plan view of the tie of Figure 5, when released;

FIGURE 8 is a perspective view of a fourth embodiment of plastics tie in accordance with this invention; FIGURE 9 is a plan view of the tie of Figure 8, when fastened; and

FIGURE 10 is a plan view of the tie of Figure 8, when released.

Referring to Figure 1 of the drawings, there is shown a one-piece releasable tie moulded from a plastics material such as polypropylene or nylon. The tie comprises a flat elongate strap 10 provided with a series of transverse ratchet serrations (not shown) on one side and with a head 11 at one end, the head projecting from the opposite side of the strap 10.

The head 11 comprises an inner end wall 12, an outer end wall 13 and a pair of

opposite side walls

14,15. A passage 16 extends through the head 11 from an insertion opening to an outlet. The passage 16 comprises an enlarged portion having a width which is only slightly greater than the width of the strap 10 which is to be passed through the passage from the insertion opening to the outlet.

The inner end wall 12 of the head 11 defines the floor of the passage 16, and a resiliently flexible pawl 18 is joined to the floor. The pawl 18 projects into the enlarged region of the passage 16, in order to engage the strap serrations when the strap 10 is inserted into the passage 16.

One of the side walls 14 is connected to one side of the outer end wall 13 by a flexible web 20. The other side of the outer end wall 13 comprises an extension 21 which extends around the opposite side wall 15. A catch 22 is provided on the outer end of the extension 21 for engaging a complementary formation 23 on the outer surface of the side wall 15. A lever 24 extends outwardly from the extension 21 adjacent the catch 22.

When the tie is tied, the pawl 18 engages the strap serrations to prevent loosening. However, the strap 10 can be released by actuating the lever 24 to disconnect the catch 22 from the formation 23 on the side wall 15, thereby allowing the end wall 13 to pivot about the web 20 into the position shown in dotted lines. It will be appreciated that this releases the strap from the pawl, so that the tie can be loosened.

Referring to Figure 2 and 3 of the drawings, there is shown an alternative embodiment of one-piece releasable tie moulded from plastics material.

The tie comprises a flat elongate strap 30 provided with a series of ratchet serrations (not shown) on one side thereof and with a head 31 at one end, the head 31 projecting from the opposite side of the strap. A passage 33 extends through the head. The head 31 comprises an enlarged inner end wall 32 which defines a floor of the passage 33. A pawl 34 extends into the passage 33 from its floor. The pawl 34 is disposed between a pair of guides 35 having shoulders along which longitudinal side edges of the strap 30 slide, as the strap is pulled through the passage 33.

The head 31 comprises side walls 36 that extend outwardly in respective opposite directions from the inner end wall 32, around the guides 35, to an outer end wall 37, which defines the roof of the passage 33.

The outer end wall 37 of the head 30 serves to hold the strap 30 against the pawl 34 when the strap is passed through the passage 33. The pawl 34 engages the strap serrations and prevents loosening of the tie.

Referring to Figure 4 of the drawings, the tie can be released by squeezing the side walls 36 of the head together: this causes the outer end wall 37 of the head to move away from the inner wall 32, thereby increasing the distance between the roof and floor of the passage 33. The strap 30 is now able to move away from the pawl 34 so that the tie can be loosened.

Referring to Figures 5 and 6 of the drawings, there is shown an alternative embodiment of one-piece releasable tie moulded from plastics material.

The tie comprises a flat elongate strap 40 provided with a series of ratchet serrations (not shown) on one side thereof and with a head 41 at one end, the head 41 projecting from the opposite side of the strap.

The head 41 comprises a body 42 having a pair of substantially parallel arms 43 that project from a rear surface thereof and define a passage 44 therebetween. The outer ends of the arms 44 are turned inwardly to define formations 45.

A pawl 46 extends from the body 42, between the arms 43 and into the passage 44. Each arm 43 is connected to a lever 47 that extends outwardly and rearwardly in the direction of the strap extension.

The formations 45 on the arms 43 form the roof of the passage 44 and serve to hold the strap 40 against the pawl 46 as the strap is pulled through the passage 44.

Referring to Figure 7 of the drawings, the tie can be released by squeezing the levers 47 together: this causes the arms 43 to bend back, thereby moving the formations 45 away from the pawl 46, so that the strap 40 disengages from the pawl 46. The formations 45 may move apart sufficiently enough for the head 41 to fully release the strap 40.

When the levers 47 are released, the arms 43 return to their as-moulded position shown in Figures 5 and 6. However, some plastic deformation of the arms may occur over time and thus they may not fully return to their as-moulded position.

Referring to Figures 8 to 10 of the drawings, there is shown an improvement to the tie of Figures 5 to 7 and like parts are given like reference numerals. In this embodiment, the outer ends of the levers 47 are connected to respective sides of the body 42 by webs 50: these webs 50 increase the cross-sectional area of plastics material which is deformed when the levers 47 are squeezed and thus they help to reduce the effects of plastics deformation.

The embodiments of Figures 2 to 10 are each released by squeezing the head of the tie. It will be appreciated that such ties can easily be released by persons wearing gloves. Furthermore, the ties return to their as-moulded condition when the heads are released and thus there is no need to perform any kind of resetting action before the ties are refastened.

Claims

A moulded plastics tie comprising an elongate strap provided with head at one end and with a series of ratchet serrations on one side thereof, a pawl in the head for engaging the strap serrations when the strap is passed through a passage in the head and means for displacing a portion of the head, opposite the pawl, in order to release the strap from the pawl.
A moulded plastics tie as claimed in claim 1, in which the displacing means is arranged to increase the height of the passage, between a floor and roof thereof, from the height of the passage in the as-moulded condition of the tie.
A moulded plastics tie as claimed in claims 1 or 2, in which the tie is a one-piece moulding of plastics material, the release means being deformable from its as-moulded condition to cause the height of the passage to increase, the deformable portion of the release means being greater in cross-sectional area than a flexure point of the pawl, so that the deformable portion of the release means is less susceptible to plastics deformation than the pawl.
A moulded plastics tie as claimed in any of claims 1 to 3, in which the roof of the passage comprises a wall that can be moved to increase the height of the passage.
A moulded plastics tie as claimed in claim 4, in which roof and floor of the passage are preferably interconnected by respective side walls extending on opposite sides of the passage, one of the side walls comprising a pivot and the opposite side wall comprising a lock, which can be released to disconnect the roof from the floor along one side of the passage, the pivot enabling the roof to move away from the floor of the passage when the lock is released.
A moulded plastics tie as claimed in any of claims 1 to 3, comprising a projection that extends outwardly in respective opposite lateral directions with respect to the passage, the projection forming a laterally compressible head portion, which can be compressed to increase the height of the passage.
A moulded plastics tie as claimed in claim 6, in which the roof and floor of the passage are interconnected by resiliently flexible side walls which extend outwardly in respective opposite lateral directions intermediate their opposite ends, and which define said laterally compressible head portion.
A moulded plastics tie as claimed in claim 6, in which the roof of the passage comprises a pair of side-by-side formations disposed on respective arms that extend forwardly from a body portion of the head to define respective opposite side walls of the passage, the arms being connected to respective levers that extend laterally outwardly with respect to the passage, in a rearward direction.
A moulded plastics tie as claimed in claim 8, in which the levers are connected to the body of the head by flexible webs.
A moulded plastics tie as claimed in any preceding claim, in which the pawl extends from a portion of the head to which the strap is attached, in order to increase the strength of the tie.