Strapping tool

Abstract: A hand-held tension-weld strapping tool (1) for sequentially tensioning and welding together overlapping portions of strapping (8) comprises a handle (2), a motor control arm (3) arranged to actuate a motor, a weld actuating arm (4) and a mechanical interlock (7) for holding the motor control arm (3) in an actuated position during a welding cycle. In the preferred embodiment, the mechanical interlock is a cranked extension portion (7) of the motor control arm (3) which, in use, is trapped between the handle (2) and the weld actuating arm (4) when the weld actuating arm is moved to an operative position.

Description: The present invention relates to a modification to a hand-held tension-weld strapping tool. Tension-weld strapping tools are typically used to apply a length of polymeric strapping around a package to form a sealed tensioned loop which securely binds the package for shipping, storage and merchandising. In manually operated tension-weld strapping tools, a length of strapping is first looped around a package and subsequently an operator introduces overlapping ends of the strapping into a strap feeding mechanism of the tool. A tension is then applied to the strap by a feed wheel mechanism driven by a pneumatic motor. The pneumatic motor is actuated by the operator gripping a motor control arm. Finally, the strap is sealed by friction welding overlapping portions of the strapping and cutting away any excess. The friction welding cycle is initiated by moving a weld actuating arm into an operative position. The operator must maintain a grip on the motor control arm throughout the welding cycle to ensure the pneumatic motor remains switched on. Accordingly, the formation of a reliable seal is dependent upon the operator maintaining a grip on the motor control arm during the entire tension-weld cycle. FR-A-2193693 discloses a friction welding tool according to the first part of claim 1 including a mechanical interlock between a weld jaw operating handle and a strap tension controlling handle. The mechanical interlock ensures that strap tensioning and strap welding may not be carried out simultaneously by causing the tensioning mechanism to be open while the weld jaw is applied. Fully and semi-automatic strapping tools do exist but these require complex and relatively expensive electronic control components. According to the present invention, a hand-held tension-weld strapping tool for sequentially tensioning and welding together overlapping portions of strapping, the strapping tool having a handle, a motor control arm arranged to actuate a motor, a weld actuating arm and a mechanical interlock characterised in that the mechanical interlock acts between the motor control arm and the weld actuating arm to hold the motor control arm in an actuated position during a welding cycle. In the present invention, a mechanical interlock is provided which holds the motor control arm in an actuated position during the welding cycle of the tool. Accordingly, the operator is not required to continue to hold the motor control arm during the welding cycle and is free to carry out other tasks. Furthermore, the reliability of the seal is no longer dependent on the operator. Preferably, the mechanical interlock acts between the motor control arm and the weld actuating arm. Preferably, the mechanical interlock comprises a cranked extension portion of the motor control arm which, in use, is trapped between the handle and the weld actuating arm when the weld actuating arm is moved to an operative position. An example of the present invention will be described in detail with reference to the accompanying drawings, in which:- Figure 1 shows a length of strapping being introduced into one example of a hand-held tension-weld strapping tool in accordance with the present invention; Figure 2 shows the tension-weld tool of Figure 1 applying a tension to the strapping; and, Figures 3 and 4 show the tension-weld tool friction welding overlapping portions of the strapping to form a seal. A hand-held tension-weld strapping tool 1 shown in Figures 1 to 4 comprises a handle 2, a motor control arm 3 arranged to actuate a pneumatic motor housed in the handle 2, a weld actuating arm 4 and an operating lever 5. The tension-weld tool 1 also comprises a feed wheel and welding mechanism 6. As shown in the Figures, the motor control arm 3 includes a cranked extension portion 7, the function of which is described in detail below. As shown in Figure 1, an operator loops a length of polymeric strapping 8 around a package. Overlapping portions of the strapping 8 are then inserted into the feed wheel and welding mechanism 6 of the tension-weld tool 1 by depressing the operating lever 5. Next, as shown in Figure 2, a tension is applied to the strap 8 by the operator gripping the motor control arm 3 to actuate the pneumatic motor. Initial actuation of the pneumatic motor drives the feed wheel mechanism 6 until a pre-determined strap tension is achieved, whereupon the pneumatic motor stalls leaving the strap held in tension. Once the pneumatic motor has stalled, the motor control arm 3 is maintained in the actuated position whilst the weld actuation arm 4 is pulled back to initiate the friction welding cycle. Once in the position shown in Figure 4, the weld actuating arm 4 traps the cranked extension portion 7 of the motor control arm 3 in position, thus holding the pneumatic motor on whilst the welding mechanism 6 friction-welds the overlapping portions of strapping 8 to form a reliable seal. The cranked extension portion 7 of the motor control arm 3 acts as a mechanical interlock so that the operator does not have to maintain a grip on the motor control arm 3 and handle 2 during the welding cycle. Accordingly, a reliable seal is guaranteed and the operator is free to leave the tool to finish the welding cycle and allow the seal to cool whilst he carries out other tasks. A further advantage is that existing manually operated tools supplied with a conventional motor control arm may be retro-fitted with a modified motor control arm 3 in accordance with the present invention at very little cost. The tension-weld strapping tool of the present invention gives a more robust, reliable and cheaper alternative to existing fully or semi-automatic strapping tools.

Claims: A hand-held tension-weld strapping tool (1) for sequentially tensioning and welding together overlapping portions of strapping (8), the strapping tool (1) having a handle (2), a motor control arm (3) arranged to actuate a motor, a weld actuating arm (4) and a mechanical interlock (7) characterised in that the mechanical interlock (7) acts between the motor control arm (3) and the weld actuating arm (4) to hold the motor control arm (3) in an actuated position during a welding cycle. A hand held strapping tool according to claim 1, in which the mechanical interlock comprises a cranked extension portion (7) of the motor control arm (3) which, in use, is trapped between the handle (2) and the weld actuating arm (4) when the weld actuating arm (4) is moved to an operative position. A motor control arm (3) for a hand-held tension-weld strapping tool (1) according to claim 1 or claim 2, wherein the motor control arm (3) is provided with a cranked extension portion (7) adapted to co-operate with a weld actuating arm (4) of the tension-weld strapping tool (1) to form a mechanical interlock.

Inventors: OSELAND PETER, OSELAND, PETER
Applicants: ITW LTD, ITW LIMITED
Application year: 1996
Main classification: B65B13
IPC codes: B65B13