AUTOMATIC TIE GUN

Abstract: A tool for applying a flexible, one-piece plastics tie around a bundle of cables drives the tie tail-­ first from the tool where it is guided around the bundle so that, upon completion of this step, the free end of the tail (10) is spaced from but aligned with and directed towards a aperture through a head (16) at the other end of the tail. A pushing element (35) of the tool is then displaced to engage in a notch (23) in an edge of the tail, to push the free end of the tail through the head, where it interlocks.

Description: This invention relates to an automatic tool or gun for applying flexible, one piece plastics ties around for example a bundle of cables, each tie having a flat tail and an apertured head at one end of the tail. The invention also relates to a tie for use by the tool. European patent 0 035 367B discloses an automatic tie gun which feeds from a supply of ties in the form of a bandolier or belt in which the ties are disposed side-by-side with each other and are interconnected by integral bridging elements. This arrangement provides very considerable advantages as regards feeding the gun because the ties can be moulded in bandolier form and do not require assembling individually into a magazine, as in other tie guns. The gun described in European patent 0 035 367B includes indexing means for advancing the bandolier such that the leading tie thereof is stepped laterally into a tail-forward, ready position within the gun, means for cutting the leading tie from the bandolier, means for driving tail-first from the gun the tie which is in the tail forward, ready position, and means at the forward end of the gun for guiding the tie tail around the bundle to be tied as the tie is driven from the gun and arranged so that the free end of the tail passes through the apertured head to interlock therein. The gun further includes means for engaging the free end of the tail, which is projecting through the apertured head of the tie, and driving it to tension the tie around the bundle being tied, a knife for cutting the tail behind the head and a tension-sensing means for actuating the knife when a predetermined tension in the tie is reached. In the gun illustrated in the drawings of European patent 0 035 367B, a reciprocating push rod is provided for pushing the tie tail-first out of the gun and this push rod is provided with means for engaging the free end of the tail, once passed through the apertured head of the tie, so that the return movement of the push rod serves to pull the tail through the head and tension the tie. However the required length of stroke of the push rod necessarily leads to the gun having an undesirably large overall length, which is contrary to a preference for the gun to be hand-held in use and therefore compact and light in weight. Further, in the gun illustrated in European patent 0 035 367B, the head of the tie is bent relative to the remainder of the tail so that its aperture is ready to receive its free end of the tail as the tail, after being guided around the bundle to be tied, is guided back into the gun whilst the head is being driven forwardly by the push rod over the final portion of its travel. This bending of the head leads to complexities and so too does removal of the cut-off tail end of the tie in the same passage as the next tie is to be driven forwardly during its application. European patent 0 135 396B discloses an improved tie gun in which a driven pinch wheel engages the tail of each successive tie which is in the tail-forward, ready position within the gun, to drive that tie tail-first from the gun. The tie tail is guided around the bundle to be tied so that, upon completion of the tie-driving step, the free end of the tail is spaced from the head but is aligned with and directed towards the head aperture: a threading mechanism then displaces the head towards the free end of the tail, so that the latter passes through and interlocks within the head aperture, and then the threading mechanism carries the head in the return direction. The tail interlocks within the head upon the initial displacement of the head by the threading mechanism and the return movement of the threading mechanism serves, whilst carrying the tie head, to advance the free end of the tail into engagement with another driven pinch wheel for tensioning the tail. These arrangements avoid the above-noted drawbacks of the gun illustrated in the drawings of European patent 0 035 367B, but the threading mechanism is still relatively complex and can be unreliable. The object of this invention is to provide a gun which overcomes these difficulties. In accordance with this invention there is provided a tool for applying flexible, one-piece plastics ties around for example a bundle of cables, each tie having a flat tail and an apertured head at one end of the tail, the tie applying tool comprising means for driving tail-first from the tool a tie which is in a tail-forward, ready position within the tool, means at the forward end of the tool for guiding the tie tail around the bundle to be tied as the tie is driven from the tool so that, upon completion of the tie-driving and guiding step, the free end of the tail is spaced from the head but is aligned with and directed towards the head aperture, and threading means for next engaging the free end of the tail and displacing it so that it passes through the head aperture to interlock therein. Preferably the threading means includes a displaceable pushing element which enters a notch or recess in one edge of the tie tail to push the free end of the tail through the head aperture. Also in accordance with this invention, there is provided a one-piece tie of plastics material comprising a flat tail and an apertured head at one end of the tail, a notch or recess being formed in an edge of the tail adjacent its free end for engagement by the displaceable pushing element of the threading means. An embodiment of this invention will now be described by way of example only and with reference to the accompanying drawings, in which: FIGURE 1 is a diagrammatic side view of a forward portion of a tie applying tool in accordance with this invention, showing a tie after it has been guided around a bundle of cables; FIGURE 2 is a similar view showing the tie and components of the tool after a lever has been displaced to bring the free end of the tail into alignment with the head aperture of the tie; FIGURE 3 is a view in the direction of arrow X in Figure 2, showing the positions of the tie and tool components after the threading mechanism has been displaced into engagement with the free end of the tie tail ready to push the tie tail through the apertured head of the tie; FIGURE 4 is a view similar to Figure 2, showing the positions of the tie and tool components after the threading mechanism has been displaced to push the free end of the tie tail through the apertured head of the tie and into engagement with a tensioning device; FIGURE 5 is a similar view of the tool after the threading mechanism has returned to its rest position; FIGURE 6 is a plan view of a tie bandolier for use with the tie applying tool; and FIGURE 7 is a section on the line VII - VII of Figure 6. Referring to the drawings, there is shown an automatic tool or gun for appplying flexible, one-piece plastics ties around for example a bundle of cables. The tool which is shown is arranged to feed from a bandolier of ties such as shown in Figures 6 and 7. The tie bandolier 1 comprises ties 10 disposed side by side and interconnected by narrow strips 12, 14 running along lines beyond the tail tips 18 and tie heads 16, respectively, and connected to the tail tips and heads by short filaments 12a, 14a. In each tie, the tail has one side formed with a series of transverse ratchet serrations 22 and at one end the head 16 projects from the other side of the tail and is itself wider than the tail. The head has an aperture 26 extending generally transversely of the plane of the tail, from the serrated side of the tail. The series of serrations 22 extend as far as the entry of aperture 26 as shown. Within this aperture there is formed a pivoted pawl 28 having teeth complementary to the ratchet serrations of the tail. Upon passing the free end of the tail through the head from the entry end of the aperture, the pawl rides on the serrations to permit free passage of the tail but any return movement of the tail is prevented by an interlock between the pawl in the head and the serrations on the tail. Each tie is formed in one longitudinal edge and adjacent its tail tip with a notch or recess 23 for co-operation with the threading mechanism of the tie applying tool, as will be described. The tie applying tool comprises an entry gate for receiving the leading end of a tie bandolier as shown in Figures 6 and 7, and an indexing drum for advancing the tie bandolier and to sever the leading tie from the bandolier and step it into a tail-forward, ready position within the tool: a tie in this position is shown at 10(R) in Figure 1. The tool further comprises a mechanism to drive that tie tail-forward from the tool once an upper guide jaw 58 of the tool has been pivoted closed onto a fixed lower guide jaw 57. The arrangements of the entry gate, indexing drum and tie driving mechanism are as described in our European patent 0 135 396B which is incorporated herein by reference. The tie driving mechanism comprises a driven pinch wheel 51 which engages the serrated side of the tie which is in the tail-forward ready position R to drive that tie tail-forward from the tool, and a cam wheel 52 having a recess 53 which receives the head 16 of the tie and then rotates to push on the rear end of the head to advance the tie through a final distance. As the tie driving mechanism drives the tie forward from the tool, the tail of the tie is guided around the bundle B of cables to be tied by the closed guide jaws 57, 58 and arrives at the position 10(F) shown in Figure 1. The tool includes an operating lever 30 which is pivoted to a support plate 31 of the tool and carries a pressure wheel 32. A lever 33 is also pivoted to the support plate 31 and as the operating lever 30 is driven downwards, its pressure wheel 32 bears against the lever 33 to displace it around its pivot and so bear against the free end of the tie tail to bring the latter into alignment with the aperture through the tie head 16. The tip of the tail is still spaced from the tie head, as shown in Figure 2. As the operating lever 30 continues its downwards movement, it engages a pressure wheel 34 which is mounted to the plate 31: a downwardly-projecting extension 35 of the lever 30 has an inwardly directed nose 36 which now enters the notch or recess 23 in the edge of the tie tail. The effect of the pressure wheel 34 is to urge the nose 36 into the notch 23 and thus urge the tie tail so that its other edge is pressed firmly agaist a fixed abutment 37 (Figure 3). The free end of the tail is now directed accurately towards the head aperture. Further downwards movement of the operating lever 30 causes the nose 36 to push the tail of the tie through the head to project from the lower side of the head (Figure 4). This movement inserts the free end of the tie tail between a rotary pinch wheel 38 and a fixed abutment 39. The operating lever 30 is now returned to its initial position allowing the closure lever 31 to return to its initial position (Figure 5). The pinch wheel 38 is now driven to pull the tail through the head and tension the tie: because the lever 33 is able to move to its open position, the bundle B is able to displace rearwardly as the tie is tensioned and this provides for a firmer tying of the cable bundle and a reduced protrusion of the tie head from the bundle. When the pinch wheel 38 has tightened the tie to a predetermined level of tension, a cutter is actuated automatically to sever the tail flush with the lower side of the head and jaw 58 is opened, as disclosed in our European patent 0 135 396B.

Claims: 1. A tool for applying flexible, one-piece plastics ties around for example a bundle (B) of cables, each tie having a flat tail (10) and an apertured head (16) at one end of the tail, the tie applying tool comprising means (51, 52) for driving tail-first from the tool a tie (10R) which is in a tail-forward, ready position within the tool, means (57, 58) at the forward end of the tool for guiding the tie tail around the bundle to be tied as the tie is driven from the tool so that, upon completion of the tie-driving and guiding step, the free end of the tail (10) is spaced from the head (16) but is aligned with and directed towards the head aperture, characterized by threading means (30, 33, 35) for next engaging the free end of the tail (10) and displacing it so that it passes through the head aperture (26) to interlock therein. 2. A tool as claimed in claim 1, in which the threading means includes a displaceable pushing element (35) for entering a notch (23) in one edge of the tie tail to push the free end of the tail through the head aperture. 3. A tool as claimed in claim 2, comprising an abutment (37) adjacent the other edge of the tie tail and means (34) for urging said pushing element against said one edge of the tie tail and so urge the other edge of the tie tail against said abutment. 4. A tool as claimed in claim 2, in which the threading means comprises a displacing element (33) which is displaceable, upon completion of the tie driving step, to displace an end portion of the tie tail radially inwardly relative to the bundle (B) to be tied and into alignment with the aperture through the tie head. 5. A tool as claimed in claim 4, in which the displacing element (33) is displaceable radially outwards relative to the bundle to be tied once the tie tail has been pushed through the head aperture. 6. A tool as claimed in claim 5, comprising a reciprocally movable operating element (30) which carries said pushing element (35) and is coupled to said displacing element (33). 7. A one-piece tie of plastics material comprising a flat tail (10) and an apertured head (16) at one end of the tail,characterized in that a notch (23) is formed in an edge of the tail adjacent its free end for engagement by a longitudinally displaceable pushing element (35) of a threading means. 8. A one-piece tie as claimed in claim 7, connected with a plurality of like ties into a bandolier in which the ties lie parallel to each other with their flat tails in a common plane. 9. A tool for applying flexible, one-piece plastics ties around for example a bundle (B) of cables, in combination with a bandolier which comprises a plurality of said ties connected together parallel to each other, each tie having a flat tail (10) and an apertured head (16) at one end of the tail, the tool comprising means (51, 52) for driving tail-first from the tool a tie (10R) which is in a tail-forward, ready position within the tool, means (57, 58) at the forward end of the tool for guiding the tie tail around the bundle to be tied as the tie is driven from the tool so that, upon completion of the tie-driving and guiding step, the free end of the tail is spaced from the head (16) but is aligned with and directed towards the head aperture, characterized by threading means (30, 33, 35) for next engaging the free end of the tail and displacing it so that it passes through the head aperture and interlocks therein.

Inventors: SCHLOTTKE, HORST
Applicants: BOWTHORPE-HELLERMANN LIMITED
Application year: 1990
Main classification: B65B13
IPC codes: B65B13