Description of Invention

This invention relates to the feeding of material, in the form of an elongate flexible element, lengthwise through a guide means from a supply station to a delivery station.

The invention has been devised in relation to metal spraying apparatus, of the kind wherein there is a spraying device having a body and a feeding mechanism for simultaneously feeding two metallic wires or rods (herein referred to as "wires") through guide passages which converge forwardly in the direction of wire feed, there being means for connection of an electrical supply to the wires so that an arc is established between the wires where they emerge from the guide passages, to melt the wires, there being means for providing a stream of gas to the region of the arc so that molten metal droplets are carried away from the arc in the stream of gas towards a surface to which a coating of metal is to be applied. The spraying device may be hand-held gun, which an operator is able to direct in order to spray metal where required.

Conventionally in metal spraying apparatus the wires are supplied on reels from which they are drawn and fed to the spraying device. Particularly for hand-held spraying devices the reels are usually mounted at positions remote from the spraying device itself, and are fed to the spraying device through flexible guide sleeves extending between the spraying device and a supply station at which the reels are located.

Feeding of wire through a flexible guide sleeve of any substantial length presents difficulties, since there is always a tendency for the wire to bind against the walls of the guide sleeve. Similarly, there would be a tendency for binding if the guide sleeve were rigid but curved more than minimally. Such tendency exists whether the wire is pushed through the guide sleeve from the supply station or pulled through the guide sleeve from the delivery station which is at the spraying device. Therefore a combination of both pushing and pulling the wire through the guide sleeve has been utilised, by providing means for

feeding the wire both at the supply station and at the spraying device delivery station. The usual method adopted for feeding wire is by gripping it in the nip between two rollers at least one of which is driven in the appropriate direction to feed the wire. A suitable motor, e.g. an electric motor or a fluid pressure operable motor such as an air motor, is provided for driving the roller. To prevent the wire from binding within the guide sleeve, however, it remains necessary to ensure that the rates of operation of the feeding devices at the supply station and delivery station do not differ from one another, and to this end it has been proposed to provide torque limiting devices or driving mechanisms which allow for some degree of slippage in the feeding device at either or both of the supply station and spraying device. The requirement to provide a respective motor for each feeding device at the supply station and spraying device, and the necessity for one or more torque limiting or slipping devices, is inconvenient and expensive, and particularly in the case of a hand-held spraying device such provision increases the bulk and weight of the spraying device making it less convenient in use.

Accordingly it is the object of the present invention to overcome or reduce one or more such disadvantages.

According to one aspect of the present invention, we provide a method of feeding material in the form of an elongate flexible element lengthwise through a guide means, from a supply station to a delivery station, by engaging the material by respective feed means provided at each of said stations, wherein said respective feed means are operated in coordination with one another by a drive means extending therebetween.

Preferably the feed means at one of said stations is driven by a motor provided at said one station, whilst the feed means at the other station is driven by said drive means extending from the first station and driven by said motor.

According to another aspect of the invention, we provide apparatus for the feeding of material in the form of an elongate flexible element lengthwise through a guide means, from a supply station to a delivery station for such

material, comprising respective feed means at each of said supply station and said delivery station, for engaging and feeding said material, and drive means extending between said respective feed means to provide a driving connection therebetween whereby operation of each of said feed means is coordinated with the other thereof.

By providing drive means providing a driving connection between the feed means at each of the supply station and delivery station, the present invention enables the material to be fed through a flexible or curved guide element by being both "pushed" and "pulled" therethrough, whilst at the same time achieving the required coordination of the operation of the feed means at each of the supply station and delivery station with one another. The complexity of providing individual motors for the feed means at each station and torque limiters or like devices is avoided.

Preferably the drive means comprises an assembly of the type generally known as a flexible drive cable, wherein a cable element which is flexible but torsionally relatively rigid has its opposite ends connected to respective rotary drive components, and is disposed within a flexible casing.

Preferably a drive motor is provided for driving the feed means provided at the supply station, and the flexible drive cable has a connection to said motor and extends to provide a driving connection to the feed means at the delivery station.

The feed means may be of known type wherein the material is gripped, for being fed, in the nip between rollers.

According to another aspect of the invention, we provide metal spraying apparatus comprising a spraying device and means for feeding at least one metallic wire to the spraying device from a supply thereof, wherein the means for delivering the wire to the spraying device comprises apparatus according to the second aspect of the invention as above set forth, with said delivery station being disposed at the spraying device.

Preferably the spraying device, which is provided with or constitutes the delivery station of the wire feeding apparatus, comprises a hand-held gun and the feed means thereat is the one which is arranged to be driven by way of the drive means, from the motor provided at the supply station. Preferably the apparatus further comprises a respective flexible guide sleeve for the at least one wire, extending from the supply station to the spraying device.

Therefore, in metal spraying apparatus according to the invention, a spraying device in the form of a hand-held gun is relatively light and easy to use since it does not require to be provided with a motor to operate the feed means thereat, although it will be appreciated that there is the requirement for a connection of such a hand-held gun to the flexible drive means. Flexible drive cables can, however, be of relatively light weight and thus not substantially hinder use of a hand-held spraying gun.

Conveniently a flexible driving cable may be connected to a handle portion of a spraying device in the form of a hand-held gun, and a rotary shaft element extend within such handle portion to a reduction gearing means (e.g. a worm gear arrangement) provided for driving the feed means from said rotary shaft element.

The feed means is preferably of conventional type as referred to above, wherein each wire is gripped in a nip between two rollers at least one of which is driven.

The invention will now be described by way of example with reference to the accompanying drawings, of which:-

Figure 1 illustrates diagrammatically the principle of the present invention:

Figures 2 and 3 are respectively a side elevation and plan, somewhat simplified, of part of the apparatus according to the invention;

Figures 4 and 5 are respectively a partially sectioned side elevation, and plan view, of a further part of the apparatus.

Referring firstly to Figure 1 of the drawings, this illustrates diagrammatically the main elements of a metal spraying apparatus of the kind which comprises a spraying device which is fed with two metallic wires which are connected, at the spraying device, to a source of electrical power so that an electric arc is established between the wires, so as to melt the wires, and wherein a stream of compressed air or other gas is directed to the region of the arc so that molten metal droplets are carried away from the arc towards a surface to which a coating of metal is to be applied.

In Figure 1, the spraying device which is a hand-held pistol or gun is represented at 10. The two wires are stored on reels 11 at a supply station. At the supply station, the wires 12, 13 are fed by a feed device 14 through respective flexible guide sleeves 15, 16 which extend to the spraying device 10. The spraying device 10 is also provided with a feeding device so that the wires are both "pushed" and "pulled" through the guide sleeves 15, 16, thereby ensuring that the wires have little or no tendency to bind within the guide sleeves 15, 16. It will be appreciated that such binding could otherwise be a problem, particularly when the guide sleeves are lying in a configuration which is far from straight. The feeding device provided at the spraying device 10 is driven in synchronism with the feeding device 14, from a motor provided at the feeding device 14, by way of a flexible drive assembly 17 extending between the two feeding devices, thereby ensuring that the two feeding devices operate in synchronism with one another to overcome, as far as possible, the potential problem of binding of the wires within their guide sleeves.

The motor associated with the feed device 14 may be an electric motor or a fluid pressure, e.g. air, motor and there is provided means 18 for controlling such motor in accordance with demand. Not illustrated in Figure 1, but necessarily present and of conventional type, are electrical connections to the spraying device 10 so that the arc is established between the wires thereat, and a connection for air or other gas to cause metal droplets from the arc to be sprayed in the required direction.

Referring now to Figures 2 and 3 of the drawings, these show, in somewhat simplified form, an embodiment of a feed device such as indicated at 14 in Figure 1. The feed device comprises a base 10 which carries a compressed air operated motor 21 whose output shaft is connected by a coupling 22 to the input shaft 23 of a worm drive gearbox 24. Within the gearbox 24 the shaft 23 carries a worm gear meshing with a pinion on a transverse shaft 25 such that the shaft 25 is driven at a high reduction ratio compared with the shaft 23. The shaft 23 extends out of the other side of the gearbox 24 and is connected by a coupling 26 to the inner cable of a flexible drive cable assembly indicated at 27. The outer cable or casing of the flexible drive cable assembly is held at 28 by a support 29 extending from the base 20.

The transverse shaft 25 which constitutes the output shaft of the gear box 24 extends out of the gear box on both sides thereof, and is provided at each end with a respective drive roller 30 provided in its periphery with an annular groove 31 of the dimension suitable for the size of wire which is to be fed by the device. Above the drive rollers 30 are disposed respective pressure rollers 32 and these are rotatably carried by transversely extending portions 33 of a member 34 which at one end is pivotally supported at a clevis 35 to the upper part of the housing of the gear box 24 and at its other end is spring biased downwardly by a compression spring 36 disposed on a pin 37 extending upwardly from a clevis 38. The pin 37 extends through an aperture in the end of the member 34 and above such aperture the spring 36 abuts the surrounding part of the member 34 and reacts against a nut 39 at the upper end of the pin. The member 34 is also provided with a handle 40 which is manually graspable to lift the member 34 by pivoting about the clevis 35, so that the pressure rollers 32 are lifted from their spring-urged engagement with the drive rollers 30.

When air motor 21 is operated, causing drive rollers 30 to be rotated, it will be understood that respective wires gripped in the nip between each drive roller 30 and pressure roller 32 will be advanced lengthwise between the rollers.

The feed device 14 further comprises respective wire guide tubes 40 leading into the feed rollers in the direction of normal wire feed in use, and guide tubes 41 leading away from the rollers in such direction. The guide tubes 41 lead to guide spigots 42 to which are connected flexible guide sleeves 43 which extend to the spraying device to be described hereafter.

Provided in association with the device shown in Figures 2 and 3, although not illustrated, are storage reels for supplies of wire. Suitable guides are provided for guiding such wire to the feeding device, such guides being indicated in outline at 44. Such guides are generally conventional.

Referring finally now to Figures 4 and 5 of the drawings, these show a spraying device in the form of a hand-held gun. The spraying device comprises a body 50 which has a handle portion 51. At the forward end of the body 50 there is a nozzle indicated generally at 52, of generally conventional type and wherein an arc is established between the two wires fed to the nozzle through forwardly converging guide members 53. An electrical connection is established with the wires in the guide members 53 so that an arc is struck between the wires within the nozzle. Compressed air or other gas is supplied to the nozzle through a connection indicated at 54, for carrying molten metal droplets from the arc out of the nozzle towards a surface where metal is to be applied.

For feeding the wires together to the nozzle there is feed means which comprises drive rollers 55 and pressure rollers 56 arranged somewhat as above described in relation to Figures 2 and 3, the pressure rollers 56 being carried on a member 57 pivotable relative to the body 50 of the spraying device and spring biased by a spring 58 so that wire in the nip between a drive roller 55 and pressure roller 56 is gripped thereby to be advanced lengthwise between the rollers. There are wire guide tubes 60 leading to the nips between the pairs of rollers, extending from spigots 61 which provide for connection to the flexible guide sleeves 43. Further guide tubes 62 lead to the guide members 53.

The drive rollers 56 are provided on the end of a transverse shaft 64 which within the body 50 of the spraying device is provided with a pinion 65 with

which meshes a worm gear 66. The worm gear 66 is mounted on a shaft 67 which is supported in bearings 68 within the body 50. The shaft 67 connects to a shaft 69 extending lengthwise through the handle portion 51 and carried by bearings 70 therein, and at its end remote from the body 50 the shaft 69 is coupled by a form-fitting coupling indicated at 71 to the inner cable indicated at 72 of the flexible drive cable assembly which extends from the feed device of Figures 2 and 3. The outer cable or casing of the flexible drive cable assembly is held by a collar 73.

Thus, when the motor 21 of the feed device of Figures 2 and 3 is operated to push the wires through the respective flexible guide sleeves extending to the spraying device of Figures 4 and 5, the feed means at the spraying device is also driven by way of the flexible drive cable assembly 27 so that the wire is also pulled through the flexible guide sleeves. Therefore the problem of binding of the wires within the flexible guide sleeves is overcome.

It will be appreciated that the principle of feeding wires or other elongate flexible elements through flexible, or rigid non-straight, guide sleeves or the like, as above described, is applicable to devices other than metal spraying apparatus.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.