GB2159451A - Drive arrangement for hand guided cutting torch - Google Patents

Abstract

A hand guided cutting torch has a head 12 directed at or substantially at right angles to a handle 13 and head support means 23 for supporting and guiding the head 12 over the work and a drive motor 21 in the handle 13. Transmission means transmitting drive between the motor 21 and head support means 23 includes at least one rotary member (28, Fig 2) rotating about an axis at or substantially at right angles to both the handle 13 and the head 12. The support means 23 as shown is a friction wheel 24 for rectilinear motion; alternatively the head is supported by a point (44, Fig 4) about which it revolves. The cutting means may be flame, laser or abrasive jet. <IMAGE>

Description

SPECIFICATION Drive arrangement for hand held cutting torch This invention relates to drive arrangements for hand held cutting torches. By "torch" is meant a device that directs a flame or other means capable of cutting, such, for example, as a laser beam or an abrasive jet.

A gas cutting torch is known in which the gas nozzle is supported at a fixed height over the work on a wheel which runs on the work driven by an electric motor in the handle. The advantage of such a motor drive is that the speed can be preselected and uniformly maintained for the most effective cutting operation. The known cutting torch, however, is expensive on account of having a fairly complicated drive arrangement.

The present invention provides a drive arrangement for such a torch which is less complicated and expensive and which is simple and reliable in operation.

The invention comprises a drive arrangement for a hand held cutting torch having a head directed at or substantially at right angles to a handle and head support means for supporting and guiding the head over the work and a drive motor in said handle, comprising transmission means transmitting drive between said motor and said head support means, said transmission means including at least one rotary member rotating about an axis at or substantially at right angles to both said handle and said head.

Such rotary member may comprise a first bevel wheel engaging with a second bevel wheel on the shaft of said drive motor.

The arrangement may comprise a bearing for said rotary member either side of said head, and the first level wheel may be removably mounted on said bearings. Thus the head may be arranged to be supported on the left hand side or the right hand side.

The arrangement may, however, comprises two first bevel wheels, one either side of said head, engaging with a second bevel wheel on the shaft of said drive motor.

Said rotary member may frictionally engage said head support means, and may be biassed into contact therewith.

Said head support means may comprise a drive wheel running on the work and imparting a rectilinear motion to the head - subject, of course, to any steering action by the operator.

Another form of said head support means may comprise an annulus receiving said head and adapted so that said head and said annulus can be relatively rotated and said annulus having a projecting radius arm and a point which can contact the work, relative rotation of said head and said annulus thereby causing said head to revolve about said point. Said head and said annulus may be relatively rotated by said annular member. Said point may be adjustable on said radius arm, whereby to cause said torch to cut different radius arcs or circles.

Said head support means may be removably attached to said head, and a torch may be provided with both rectilinear and circle cutting support means as above described.

Embodiments of drive arrangements for a hand held cutting torch according to the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a side elevation showing the general layout of the torch, Figure 2 is an exploded diagrammatic illustration of a first drive arrangement for the torch illustrated in Figure 1, Figure 3 is an exploded diagrammatic illustration of a second drive arrangement for the torch illustrated in Figure 1, and Figure 4 is a diagrammatic illustration of an arc or circle cutting head support.

The drawings illustrate drive arrangements for a hand held cutting torch 11 having a head 12 directed at or substantially at right angles to a handle 13 and head support means 23 for supporting and guiding the head 12 over the work 15 - in this case, a steel plate to be cut. The torch 11 as illustrated is a gas torch and has, in the handle 13, connectors 16 for attachment of oxygen and acetylene or other gas leads (not shown) and valve means 17 admitting such gases to gas conduits 18 to the torch nozzle 19 in the head 12.

In the handle 13 is resiliently mounted an electric drive motor 21 having a drive shaft 22 extending along the handle 13 to the head 12.

The head support means 23 illustrated in Figure 2 comprise a drive wheel 24 mounted on an arm 25 having a pivot 26 for engagement in a bearing 27 on the head 12 (Figure 1).

Transmission means transmitting drive between said motor 21 and the drive wheel 24 comprise a rotary member 28 comprising in each case a first bevel wheel or gear, rotating about an axis 29 at or substantially at right angles to both said handle 13 and said head 12. The said first bevel wheel or gear 28 engages (meshes) with a second bevel wheel (gear) 31 on the shaft 22 of the motor 21.

In the embodiment illustrated in Figure 2, there are two such first bevel wheels (gears) 28 engaging said second wheel or gear 31 on bearings either side of the head 12. The drive wheel 24 is driven by frictional engagement with one or other of the bevel wheels 28 being urged into contact therewith by a spring acting on the pivot arm 25 which can readily be removed from the head 12 for placement on the other side of the head, provided with a second pivot bearing therefor, as shown in dashed lines.

In the embodiment illustrated in Figure 3, there is only one first bevel wheel 28 mounted together with the drive wheel which is resiliently biased into contact with it on a bracket 38 (see inset) which can fit into the head 12 either side thereof so as to engage the bevel 28 with the bevel 31.

In either embodiment the drive wheel 24 can be mounted either side of the head 12 so as to provide the facility of supporting the head 12 above the work even near an edge. The drive wheel 24 can be driven at constant speed by the motor 21 which can be controlled as to speed and direction by a variable resistance 39 or other speed control arrangement and a pivoted switch 41 connected such that pushing forward on the switch whichever side of the pivot corresponds to the drive wheel position, i.e. left or right of the head as viewed from the handle, makes the wheel 24 drive forward, i.e. in the direction the switch is pushed.

Subject to any manually effected steering, the wheel 24 thus drives the head with a rectilinear motion at a speed which can be adjusted by the resistance 39 to what is required to effect a proper cut.

A radius cutting unit can be fitted to the head 12 instead of the drive wheel 24 arrangement. Figure 4 illustrates such a unit comprising an annulus 42 receiving the head 12 and adapted for relative rotation therewith and having a projecting radius arm 43 and a point 44 which can contact the work, relative rotation of the head 12 and the annulus 42 thereby causing the head 12 to revolve about the point 44.

The annulus 42 has a drive surface 45 which is biased into contact, in use, with the bevels 28 of the embodiment illustrated in Figure 2 or the bevel 31 in the embodiment illustrated in Figure 3, having, in the latter case, bevel gear teeth to mesh with the bevel 31.

The point 44 is adjustable on the arm 43, securable thereon by a locking screw 46.

Claims (13)

1. A drive arrangement for a hand held cutting torch having a head directed at or substantially at right angles to a handle and head support means for supporting and guiding the head over the work and a drive motor in said handle, comprising transmission means transmitting drive between said motor and said head support means, said transmission means including at least one rotary member rotating about an axis at or substantially at right angles to both said handle and said head.

2. A drive arrangement according to claim 1, said rotary member may comprise a first bevel wheel engaging with a second bevel wheel on the shaft of said drive motor.

3. A drive arrangement according to claim 1 or claim 2, comprising a bearing for said rotary member either side of said head.

4. A drive arrangement according to claim 3, comprising a first bevel wheel removably mounted on said bearings.

5. A drive arrangement according to claim 3, comprising two first bevel wheels, one either side of said head, engaging with a second bevel wheel on the shaft of said drive motor.

6. A drive arrangement according to any one of claims 1 to 5, said rotary member frictionally engaging said head support means.

7. A drive arrangement according to claim 5 or claim 6, said rotary member being biassed into contact with said head support means.

8. A drive arrangement according to any one of claims 1 to 7, said head support means comprising a drive wheel running on the work and imparting a rectilinear motion to the head.

9. A drive arrangement according to any one of claims 1 to 7, said head support means comprising an annulus receiving said head and adapted so that said head and said annulus can be relatively rotated and said annulus having a projecting radius arm and a point which can contact the work, relative rotation of said head and said annulus thereby causing said head to revolve about said point.

10. A drive arrangement according to claim 10, in which said head and said annulus are rotatively rotated by said annular member.

11. A drive arrangement according to claim 9 or claim 10, said point being adjustable on said radius arm.

12. A drive arrangement according to any one of claims 1 to 11, said head support means being removably attached to said head.

13. A drive arrangement substantially as hereinbefore described with reference to the accompanying drawings.