GB2165786A

GB2165786A - Manually-operable work tool

Info

Publication number: GB2165786A
Application number: GB08426906A
Authority: GB
Inventors: Steven George Favell
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1984-10-24
Filing date: 1984-10-24
Publication date: 1986-04-23
Also published as: GB8426906D0

Abstract

A manually-operable work tool such as a torque wrench includes an electrical switch having contact members 21, 27 which close when the wrench pre-set torque value is attained in use. <IMAGE>

Description

SPECIFICATION Manually operable work tool This invention relates to a manually operable work tool and a work station embodying such a tool.

During an assembly step of an article at a work station it is often necessary to complete the assembly step by tightening a component using a wrench before the part assembled article is passed to the next work station in an assembly line. Often further items are added to the article which make it impossible to tighten the aforesaid component later should the fact that the component has not been tightened, be noticed. This will require detaching the later added items and there is of course always the risk that the fact that the component has not been tightened will not be noticed until failure occurs in the use of the article.

The object of the invention is to provide a manually operable work tool in a simple and convenient form.

According to the invention a manually operable work tool such for example as a torque wrench, includes electrical switch means operable to provide an electrical signal when the work tool has been correctly used.

According to a further aspect of the invention the work station includes means for mounting a work piece, a manually operable tool for carrying out a specific task at the work station, electric switch means incorporated in the tool for providing an electrical signal when the tool has been correctly used and means responsive the said signal for providing an indication of the use of said tool.

In the accompanying drawings: Figure 1 is a diagrammatic plan view of a torque wrench modified in accordance with the invention, and Figure 2 is a diagrammatic illustration of a work station embodying the tool.

Referring to Figure 1 of the drawings the torque wrench includes a handle portion 10 and a head portion 12 within which is mounted a cam 13 coupled to a square section drive member 14 for connection in use to a socket. The cam is provided with a number of detents 15 and engaged with the peripheral surface of the cam is a roller 16 this being guided for movement within a bush 17. The roller is biased into engagement with the peripheral surface of the cam by a coiled compression spring 18 one end of which enyages an abutment 19 which contacts the roller.The other end of the spring engages a further abutment 20 the axial position of which within the handle portion can be adjusted so as to vary the force exerted by the spring, this adjustment being obtained by angular adjustment of a screw threaded sleeve 20A which imparts axial movement to the abutment 20 through the sleeve 20B slidable in the handle portion 10.

In use, with a socket engaged with a suitable nut, and with the handle portion moved in one direction, torque will be transmitted to the nut until, when a particular torque valve is reached, the roller will be forced outwardly against the action of the spring 18. As previously mentioned the force exerted by the spring can be varied and this alters the torque value at which outward movement of the roller takes place.

In order to provide an electrical signal indicative that the required torque value has been transmitted, there is provided an electrically insulated contact member 21 which is carried by an insulating bush 22 and which through a stem 23 carried by the bush, can be connected by way of a cable 24 to an external electrical circuit.

For engagement with the contact member 21 in order to complete an electrical connection, there is provided a contact member 27 which is mounted upon a pin 28 telescopically mounted in a stem 29 integrally formed with the abutment 19. A coiled compression spring 30 is interposed between the stem 29 and the contact member 27 and the separation of the contact members 21 and 27 is such that electrical contact therebetween will only occur when the roller has been moved outwardly by the action of a detent. When the two contact members engage the contact member 21 is effectively connected to the body of the wrench which is electrically connected by way of a further cable 31 to external apparatus. The spring 30 following engagement of the contact members 21 and 27 yields to allow movement of the roller 16 without causing damage to the contact members or the parts associated therewith.The insulating bush 22 is in screw thread engagement with the sleeve 20B and is adjustable therein to allow readjustment of the distance between the contact members 21, 27 when the torque setting of the wrench has been adjusted.

With the arrangement described only when the wrench has "yielded" indicating that the correct torque has been applied to the nut, is an electrical signal provided.

Referring now to Figure 2 the wrench is indicated at 33 and is electrically connected by means of the cables 24 and 31 to a control box 34. The work station includes a work support device 35 which in the particular example includes an air operated clamping device 36. When a workpiece is assembled to the support device, the clamping device is brought into operation to secure the workpiece to the support device and only when a signal has been received from the torque wrench 33 indicating that a nut has been correctly tightened, can the circuits of the control box cause release of the clamping device 36 to allow the workpiece to be removed from the support and passed to the next station.

It is possible to have a number of tools at a work station all embodying electrical switches which provide a signal when the particular tool has been correctly used. The control box can be responsive to the signals to ensure that the operations are carried out in the correct sequence and the control box may be provided with warning lights to indicate which tool should be used next in the assembly cycle.

Instead of providing a clamping device 36 the control box can be arranged to provide an audible or visible warning in the event that an operation has been missed. In this case of course it is clearly necessary to provide some indication to the control box that a component has been mounted in or on the support device.

Claims

1. A manually operable work tool such for example as a torque wrench, including electrical switch means operable to provide an electrical signal when the work tool has been correctly used.

2. A work station including means for mounting a workpiece, a manually operable work tool for carrying out a specific task at the work station, electric switch means incorporated in the tool for providing an electrical signal when the tool has been correctly used and means responsive to said signal for providing an indicator of the use of said tool.

3. A manually operable work tool substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.