WO1993012377A1

WO1993012377A1 - A heating tool and a heating tool element

Info

Publication number: WO1993012377A1
Application number: PCT/IE1992/000028
Authority: WO
Inventors: John Paul Oglesby; Alfred Peter Oglesby; Damian Brett; Michael John Griffin
Original assignee: Oglesby & Butler Research & Development Limited
Priority date: 1991-12-17
Filing date: 1992-12-16
Publication date: 1993-06-24
Also published as: AU3093892A

Abstract

A dehorning tool (1) comprises a handle (2) housing a gas reservoir (25). A dehorning tool element (6) is releasably connected to the handle (2). The tool element (6) comprises a horn engaging member (35) having a recess (75) for engaging and removing a horn bud. A combustion chamber housing (36) extending from the member (35) houses a gas catalytic combustion element (57) for combusting gas from the reservoir (25) for heating the horn engaging member (35). Primary exhaust outlets (56) exhaust gas from the combustion chamber (38) into an exhaust gas chamber (69) formed by an outer shield (65) extending around the combustion chamber housing (36). Secondary exhaust outlets (70) in the shield (65) are staggered from the primary exhaust outlets (56) for retarding the flow of gas through the chamber (69). The shield (65) is slidable on the housing (36) for exposing the primary exhaust outlet (56) for igniting the combustion element (57).

Description

"A heating tool and a heating tool element"

The present invention relates to a heating tool element of the type comprising a gas powered heating tool element comprising a working body member of heat conductive material, a hollow combustion chamber housing extending from the working body member forming a combustion chamber for combusting gas therein, the combustion chamber housing being of heat conductive material and being in heat conducting engagement with the working body member, a gas inlet being provided to the combustion chamber, a primary exhaust outlet being provided from the combustion chamber for exhausting gas from the combustion chamber. The invention also relates to a heating tool comprising the heating tool element. Further the invention relates to a dehorning tool and to a dehorning tool element.

Heating tools, for example, gas powered soldering tools are well known. Such soldering tools in general comprise a handle and a soldering tool element connected to the handle. A gas reservoir may be provided in the handle for supplying gas through a control mechanism to a combustion chamber in the soldering tool element for heating a soldering body member in the tool element. In general, a combustion chamber housing defines a combustion chamber and extends from the soldering body member. Fuel is combusted by a catalytic combustion element or other means in the combustion chamber and heat is conducted from the combustion chamber through the combustion chamber housing into the soldering body member. When used indoors, the heat conducted to the soldering body member is normally quite adequate for soldering purposes. However, where the soldering iron is used out of doors, particularly, in cold breezy weather, a considerable amount of heat may be lost to atmosphere from the combustion chamber housing. It has been found in many cases that the heat loss under such circumstances is so great as to reduce the heat being conducted into the soldering body member to a degree where the soldering body member has insufficient heat to melt solder. The present invention is directed towards providing a heating tool and in particular a heating tool element which overcomes these problems.

Additionally, it is known to remove horn buds from the skull of animals, typically, heifers and bullocks using a heating element. However, in general, such heating elements require a heat source which may require providing a mains AC supply to the heating element, or alternatively, connecting of the heating element to other remote sources of energy. Additionally, it has been found that dehorning tools tend to be relatively inefficient and can cause significant suffering to the animal during the dehorning process.

There is therefore a need for a heating tool, a heating tool element, a dehorning tool and a dehorning tool element which overcomes the problems of such known tools and such known elements.

The present invention is directed towards providing such tools and tool elements.

According to the invention there is provided a gas powered heating tool element comprising a working body member of heat conductive material, a hollow combustion chamber housing extending from the working body member forming a combustion chamber for combusting ^*gas therein, the combustion chamber housing being of heat conductive material and being in heat conducting engagement with the working body member, a gas inlet being provided to the combustion chamber, a primary exhaust outlet being provided from the combustion chamber for exhausting gas from the combustion chamber, wherein an outer shield extends around the combustion chamber housing and over the primary exhaust outlet for shielding the combustion chamber housing for minimizing heat loss from the combustion chamber housing, the shield defining with the combustion chamber housing an exhaust gas chamber communicating with the combustion chamber through the primary exhaust outlet, and at least one secondary exhaust outlet being provided from the exhaust gas chamber for exhausting exhaust gas from the exhaust gas chamber.

The advantages of the invention are many. A particularly important advantage of the invention is that heat loss from the combustion chamber to atmosphere is significantly reduced relative to heating tool elements known heretofore. This results from the provision of the outer shield which as well as reducing heat radiated, convected and conducted from the combustion chamber housing also forms the exhaust gas chamber which further facilitates in the reduction of heat loss from the combustion chamber. The provision of the exhaust gas chamber causes the exhaust gases to pass over the outer surface of the combustion chamber housing, thereby facilitating the transfer of further heat from the exhaust gases into the combustion chamber housing. Needless to say, the provision of the exhaust gases in the exhaust gas chamber around the combustion chamber housing prevents heat loss from the combustion chamber housing. The exhaust gas chamber also retards the flow of exhaust gases thereby further increasing heat transfer from the exhaust gases to the combustion chamber housing. Because heat loss from the combustion chamber is significantly reduced, considerably more heat is available at the working body member, and accordingly, a more efficient heating tool element is provided.

In one embodiment of the invention the primary exhaust outlet and the secondary exhaust outlet are staggered relative to each other for retarding the passage of exhaust gas through the exhaust gas chamber.

By retarding the passage of exhaust gas through the exhaust gas chamber, a greater reduction in the heat loss from the combustion chamber is achieved. In another embodiment of the invention the outer shield extends completely around the combustion chamber housing and defines therewith an annular exhaust gas chamber.

By providing the outer shield extending completely around the combustion chamber housing, heat loss from the combustion chamber housing is further reduced.

In another embodiment of the invention the outer shield is movable from a first position shielding the primary exhaust outlet to a second position with the primary exhaust outlet exposed.

By providing the outer shield so that it is movable to expose the primary exhaust outlet, ignition of the gas is facilitated. This feature, in particular, facilitates use of a catalytic combustion heating element.

Preferably, the combustion chamber housing comprises an elongated combustion chamber housing, the outer shield being axially slidable longitudinally along the combustion chamber housing between the first and second positions. The advantage of this feature of the invention is that it provides a relatively convenient construction of tool element, which is also easily operable.

Advantageously, biasing means is provided for urging the outer shield into the first position. The advantage of providing biasing means is that the outer shield is readily easily retained in the first position shielding the primary exhaust outlet and the combustion chamber housing. Indeed, by shielding the primary exhaust outlet the danger of a breeze extinguishing combustion in the combustion chamber is substantially avoided.

Advantageously, the biasing means comprises a compression spring, which is a readily available component. In one embodiment of the invention the combustion chamber housing comprises an elongated tubular member extending rearwardly from the working body member. The advantage of this feature of the invention is that it provides a relatively convenient construction of tool element, and also, a tool element which is of good construction ergonomically.

Preferably, the combustion chamber housing terminates in the gas inlet, the primary exhaust outlet extending radially through the combustion chamber housing downstream of the gas inlet. This feature provides a relatively efficient combustion chamber. For convenience the tubular member forming the combustion chamber housing is preferably of circular transverse cross-section.

To provide a more efficient combustion chamber housing and, in turn, a more efficient element, the gas inlet is provided remote of the working body member, the primary exhaust outlet is provided adjacent the working body member, and each secondary exhaust outlet is provided remote of the working body member.

Advantageously, a gas catalytic combustion heating element is provided in the combustion chamber. Preferably, the catalytic combustion element is of annular shape defining a through bore communicating with the gas inlet and being gas permeable to facilitate radial passage of gas therethrough to the primary exhaust outlet. Advantageously, the catalytic combustion element comprises a carrier of pierced stainless steel sheet material. The provision of a gas catalytic combustion heating element provides for a relatively efficient conversion of gas to heat, and also, provides a tool element which can be operated easily and safely.

In one embodiment of the invention connecting means are provided for connecting the heating tool element to a handle and to a gas supply means. Preferably, the connecting means comprises a gas supply pipe extending from the gas inlet. Advantageously, the gas supply pipe extends axially longitudinally from the combustion chamber housing. Preferably, the connecting means is releasably connectable to the handle. The provision of a releasable connecting means for connecting the tool element to the handle enables a variety of different type tool elements to be used in conjunction with the handle.

In another embodiment of the invention the working body member is releasably engageable with the connecting means. The advantage of this feature of the invention is that different types of working body members may be interchangeable with the tool element.

Advantageously, the combustion chamber housing is integrally formed with the working body member. By forming the combustion chamber housing integrally with the working body member, a particularly efficient construction of tool element is provided. Heat conduction from the combustion chamber housing into the working body member is maximised. Additionally, a relatively strong robust construction of tool element is provided. Furthermore, where the working body member is releasably engagable with the connecting means, the working body member and the combustion chamber is replaceable as a single integral unit.

In a further embodiment of the invention the working body member forms any one of the following: a soldering tip, a horn engaging element for dehorning an animal, a heated knife, and a hot air blower.

By providing a number of different working body members, the tool element may be used for different purposes.

Additionally the invention provides a heating tool comprising a handle formed by an elongated handle housing, a fuel supply means being provided in the handle housing, wherein the heating tool element according to the invention is connected to the handle housing.

The heating tool according to the invention has many advantages. By connecting the heating tool element according to the invention to the handle of the heating tool , the advantages of the heating tool element are all achieved by the heating tool.

In one embodiment of the invention a heat conducting means extends from the heating tool element to the fuel supply means through the connecting means for transferring heat from the combustion chamber to the fuel supply means for preventing freezing of the fuel.

In another embodiment of the invention the fuel supply means comprises a jet housing having a jet orifice extending therethrough, the heat conducting means being in heat conducting engagement with the jet housing. The heat conducting means conducts heat to the jet housing thereby avoiding the danger of freezing of the fuel gas passing through the jet orifice.

Further the invention provides a dehorning tool element comprising a working body member of heat conductive material, the working body member having horn engaging means formed therein, a hollow combustion chamber housing extending from the working body member forming a combustion chamber for combusting gas, the combustion chamber housing being of heat conductive material and being in heat conducting engagement with the working body member, a gas inlet being provided to the combustion chamber, a primary exhaust outlet being provided from the combustion chamber for exhausting gas from the combustion chamber.

The advantages of the dehorning tool element according to the invention are many. A horn bud can readily easily be removed from the skull of an animal. Furthermore, by virtue of the fact that the working body member is heated, any blood vessels ruptured in the animal's head as a result of dehorning are effectively simultaneously cauterised while the horn bud is being removed. Alternatively, by engaging the horn bud in the horn engaging means, and holding the horn engaging means in engagement with the horn bud for approximately ten seconds, the horn bud is sufficiently heated to kill sufficient cells of the horn bud, and shortly thereafter the horn bud is rejected by the animal, and drops off.

In one embodiment of the invention the horn engaging means is formed by a horn engaging recess extending into the working body member. It has been found that the provision of a horn engaging recess permits a horn bud to be readily easily engaged by the working body member for good heat transfer to the horn bud. Additionally, the provision of the recess enables the horn bud to be readily easily scooped from the skull of the animal.

In another embodiment of the invention the working body member is formed by a cylindrical horn engaging body member having an outer cylindrical surface and terminating at one end in a horn engaging end, the horn engaging recess extending into the horn engaging body member from the horn engaging end. This construction of working body member facilitates removal of the horn bud relatively easily.

Preferably, the horn engaging recess extends axially into the horn engaging body member. This feature enables the horn bud to be scooped relatively easily from the animal's skull. By providing the geometrical axis of the horn engaging recess coinciding with the geometrical axis of the horn engaging member, scooping of the horn bud from the animal's skull is further facilitated.

Preferably, the outer cylindrical surface of the horn engaging body member tapers towards the horn engaging end adjacent the horn engaging end. By tapering the outer cylindrical surface adjacent the horn engaging end of the horn engaging body member scooping of the horn bud is further facilitated, and additionally, simultaneous cauterising of ruptured blood vessels is further enhanced by the provision of the tapered portion.

In one embodiment of the invention the combustion chamber housing is an elongated housing extending longitudinally rearwardly from the end of the horn engaging body member remote from the horn engaging end. Advantageously, the geometrical axis of the combustion chamber housing coincides with the geometrical axis of the horn engaging body member. This arrangement of combustion chamber housing relative to the horn engaging body member provides a particularly convenient construction of a dehorning tool element, and furthermore, provides a dehorning tool element which is efficient in operation.

Advantageously, the horn engaging recess is of partly spherical shape. Preferably, the horn engaging recess is of hemispherical shape. It has been found that by providing a horn engaging recess of partly spherical shape and preferably, hemispherical shape a tool element which is particularly efficient in. use is provided, and good heat transfer to the horn bud is provided. Advantageously, the horn engaging recess is of size substantially similar to that of a horn bud, and preferably, the horn engaging recess substantially defines the horn bud.

Advantageously, a bore extends through the working body member terminating in the horn engaging recess for facilitating removal of horn debris from the horn engaging recess.

Preferably, the combustion chamber housing is of circular cross- section to provide a convenient construction of tool element.

Advantageously, the working body member is of solid construction for maximising the availability of heat in the working body member.

The invention further provides a dehorning tool comprising a handle, a dehorning tool element connected to the handle by a connecting means, the dehorning tool element being according to the invention.

The invention will be more clearly understood from the following description of some embodiments thereof given by way of example only, with reference to the accompany drawings, in which:

Fig. 1 is a perspective view of a dehorning tool according to the invention including a dehorning tool element also according to the invention,

Fig. 2 is a perspective view of the dehorning tool of Fig. 1 from a different direction,

Fig. 3 is a plan view of the dehorning tool of Fig. 1,

Fig.4 is a cross-sectional elevational view of the dehorning tool of Fig. 1 on the lines IV - IV of Fig. 3,

Fig. 5 is an enlarged cross-sectional elevational view of portion of the dehorning tool of Fig. 1 also on the line IV - IV of Fig. 3,

Fig.6 is a view similar to Fig. 5 showing part of the portion of Fig. 5 in the different position,

Fig. 7 is a cut-away perspective view of the dehorning tool element of the dehorning tool of Fig. 1,

Fig.8 is a perspective view of the dehorning tool element of Fig.7 illustrated in a different position, Fig. 9 is a cross-sectional end view of the dehorning tool element on the line IX- IX of Fig. 5,

Fig. 10 is a perspective view of portion of the dehorning tool element of Fig. 1,

Fig. 11 is a perspective view of a portion of the dehorning tool of Fig. 1,

Fig. 12 is a perspective view of another portion of the dehorning tool of Fig. 1,

Fig. 13 is a cross-sectional elevational view of a soldering tool element also according to the invention,

Fig. 14 is a view similar to Fig. 13 of a heated knife tool element also according to the invention,

Fig. 15 is a view similar to Fig. 13 of another soldering tool element according to another embodiment of the invention, and

Fig. 16 is a cross-sectional view similar to Fig. 5 of a dehorning tool element according to another embodiment of the invention.

Referring to the drawings and initially to Figs. 1 to 15 thereof, there is illustrated a heating tool according to the invention indicated generally by the reference numeral 1 which may be used for many purposes, for example, as a dehorning tool for dehorning animals, as a soldering tool, as a heated knife. The heating tool 1 is portable and comprises a handle 2 formed by an elongated hollow handle housing 3 and any one of a number of heating tool elements also according to the invention and indicated generally by the reference numeral 4 releasably connected to the handle housing 3. In Figs. 1 to 12 the heating tool element 4 illustrated connected to the handle housing 3 is a dehorning tool element 6. Other heating tool elements 4 which may also be releasably connected to the handle housing 3 are illustrated in Figs. 13 to 15. The heating tool element 4 illustrated in Figs. 13 and 15 are soldering tool elements 7 and 9. The heating tool element 4 illustrated in Fig. 14 is a heated knife element 8. For convenience the heating tool 1 and dehorning tool element 6 will first be described with reference to Figs. 1 to 12.

The handle housing 3 comprises an elongated outer tubular shell 10 of circular cross-section and of stainless steel. An inner housing 12 of injection moulded plastics material which will be described in more detail below is of circular outer cross-section and is mounted within the outer shell 10. A mounting flange 15 of steel having a bore 16 extending therethrough is mounted on the outer shell 10 for connecting the tool element 4 to the handle 2 as will be described below. A portion 17 of the bore 16 engages the outer shell 10 with an interference fit. A grub screw 18 through a threaded hole 19 in the flange 15 engages a receiving hole 20 in the outer shell 10 for securing the mounting flange 15 on the outer shell 10. A receiving flange 22 of ■ injection moulded plastics material is secured to the mounting flange 15 and receives the tool element 4 as will be described below.

Fuel supply means for supplying fuel to the tool element 4 comprises a reservoir 25 formed in the inner housing 12 in the handle 2. An end cap 26 with a filler valve 27 closes the reservoir 25. Fuel gas from the reservoir 25 is supplied to the tool element 4 through an elongated main passageway 30 of circular cross-section extending in the inner housing 12 from the reservoir 25 to the mounting flange 15. Control means which forms part of the fuel supply means and which is described below is housed in the main passageway 30 for vaporising and controlling the rate at which fuel gas is del vered to the tool element 4.

Returning now to the tool element 4 which in this case is the dehorning tool element 6, the dehorning tool element 6 comprises a working body member, namely, a horn engaging member 35 of heat conductive material, in this case, solid copper, nickel plated. The horn engaging member 35 is described in detail below. A combustion chamber housing 36 is formed by an elongated tubular member 37 of circular cross-section extending longitudinally rearwardly from the horn engaging member 35. The combustion chamber housing 36 forms a combustion chamber 38 within which fuel gas is combusted for heating the horn engaging member 35. The tubular member 37 is of heat conductive material, namely, nickel plated copper and is in heat conducting engagement with the horn engaging member 35 for conducting heat from the combustion chamber 38 to the horn engaging member 35. In this case the tubular member 37 is integrally machined with the horn engaging member 35 from the same piece of copper material and subsequently nickel plated. The tubular member 37 terminates in a gas inlet opening 39 remote from the horn engaging member 35. A gas supply pipe 40 extends from the combustion chamber housing 36 and delivers fuel gas to the combustion chamber 38 through the gas inlet 39 from the handle 2 as will be described below.

The gas supply pipe is of double skin construction comprising an inner pipe 41 and an outer pipe 42 both of stainless steel and of circular cross-section. A circular mounting ring 44 of brass and a sleeve 45 of stainless steel and of circular cross-section connects the gas supply pipe 40 to the combustion chamber housing 36. The sleeve 45 extends along the tubular member 37 from the horn engaging member 35 and is a relatively tight sliding fit thereon. A circular securing ring 46 of brass extends around the sleeve 45. A screw 51 through a hole 47 in the securing ring 46 and a hole 48 in the sleeve 45 engages a threaded hole 49 in the horn engaging member 35 for releasably securing the horn engaging member 35 in the sleeve 45. The sleeve 45 is secured to the mounting ring 44 by crimping the sleeve 45 into an annular recess 50 extending around the mounting ring 44. The outer pipe 42 is also secured to the mounting ring 44 by crimping the outer pipe 42 into the annular recess 50. The outer pipe 42 terminates in a connecting means, namely, a connecting flange 54 for releasably connecting the dehorning tool element 6 to the receiving flange 22. The connecting flange 54 is welded to the outer pipe 42 and is releasably secured to the receiving flange 22 and the mounting flange 15 by four screws 55 through holes 53 in the connecting flange 54 and holes (not shown) in the receiving flange 22. The screws 55 engage threaded holes (not shown) in the mounting flange 15. Spacers 21 and 23 integrally moulded with the receiving flange 22 space the receiving flange 22 from the connecting flange 54 and the mounting flange 15, respectively, and accordingly, the receiving flange 22 acts as a heat break to minimise heat transfer into the outer shell 10 of the handle 2. The inner pipe 41 engages the mounting ring 44 with an interference fit.

A pair of primary exhaust outlets 56 extend radially from the combustion chamber 38 downstream of the gas inlet 39 for exhausting burnt gases from the combustion chamber 38. The primary exhaust outlets 56 are formed by circular openings 61 extending radially through the tubular member 37 on opposite sides thereof, adjacent the horn engaging member 35, and circular openings 68 in the sleeve 45, which are of similar size to, and are aligned with the openings 61.

A permeable gas catalytic combustion heating element 57 which comprises a catalyst carrier 58 of pierced stainless steel sheet material and of tubular shape is mounted in the combustion chamber 38 for converting the fuel gas to heat. The carrier 58 is coated with a precious metal catalyst material (not shown) which will be known to those skilled in the art. The carrier 58 defines a bore 59 which receives gas from the gas inlet 39. Gas passes radially through the carrier 58 where it reacts with the catalyst material (not shown) on the carrier 58, and burnt gases pass through the primary exhaust outlets 56. The carrier 58 is releasably retained in the combustion chamber 38 by a pin 60 extending transversely across the gas inlet 39 through bores 62 in the tubular member 37. A spigot 63 of heat conducting material, namely, copper is secured in a bore 64 in the horn engaging member 35 and extends into the combustion chamber 38 through the bore 59 in the carrier 58 for transferring heat from the combustion chamber 38 internally into the horn engaging member 35.

An elongated outer shield 65 of stainless steel and of circular cross-section extends around the combustion chamber housing 36 for minimizing heat loss from the housing 36. The shield 65 is crimped onto a pair of circular spaced apart end rings 66 and 67 of brass which extends around and slidably engage the sleeve 45. The shield 65 and end rings 66 and 67 are together slidable along the sleeve 45 and the outer pipe 42 from a first position illustrated in Figs. 1 and 5 with the shield 65 shielding the combustion chamber housing 36 and the primary exhaust outlets 56 to a second position illustrated in Figs. 3 and 6 with the primary exhaust outlets 56 exposed to facilitate igniting the catalytic combustion element 57. The end rings 66 and 67 space the shield 65 apart from the sleeve 45 to form with the sleeve 45 and the shield 65 an annular exhaust gas chamber 69 which communicates with the combustion chamber 38 through the primary exhaust outlets 56 when the shield 65 is in the first position. Four secondary exhaust outlets 70 extend through the shield 65 for exhausting gas from the exhaust gas chamber 69. The secondary exhaust outlets 70 are spaced apart circumferentially around the shield 65 at an end remote from the horn engaging member 35 and are longitudinally staggered from the primary exhaust outlets 56 when the shield 65 is in the first position for retarding the passage of gas through the exhaust gas chamber 69 for minimizing heat loss from the combustion chamber housing 36. Biasing means, in this case, a compression spring 72 acting between a flange 73 on the ring 67 and the connecting flange 54, urges the shield 65 into the first position. The shield 65 by shielding the primary exhaust outlet 56 also avoids any danger of the catalytic combustion element 57 being extinguished by wind or the like when the tool 1 is used out of doors.

Returning now to the horn engaging member 35, the horn engaging member 35 is formed by a solid cylindrical horn engaging body member 71 having an outer cylindrical surface 74 which terminates in a circular front horn engaging end face 76 and a rear end 77. The combustion chamber housing 36 extends from the rear end 77 and the geometrical axes of the cylindrical body member 71 and the combustion chamber housing 36 coincide. A horn engaging means for engaging a bud of a horn in an animal's skull is provided by a horn engaging recess 75 of substantially hemispherical shape extending into the cylindrical body member 71 from the horn engaging end face 76. The geometrical axes of the cylindrical body member 71 and the horn engaging recess 75 are co-axial. The horn engaging recess 75 is preferably sized to be of size substantially similar to the size of the horn bud of the animal. The cylindrical body member 71 tapers at 78 towards the horn engaging end face 76 for facilitating manipulation of the horn engaging member 35 during removal of a horn bud from an animal's skull. The tapered portion 78 of the cylindrical body member 71 defines a circular peripheral edge 135 of the horn engaging end face 76. The horn engaging recess 75 defines a circular peripheral edge 136 on the horn engaging end face 76 which defines with the peripheral edge 135 of the horn engaging end face 76 a parting rim 137 extending around the recess 75 for parting a horn bud from the animal's skull as the horn bud is being scooped up in the recess 75 from the skull by the horn engaging member 35. The rim 137 essentially acts as a cutting edge for parting the horn bud from the animal's skull, and by maintaining the radial width of the rim 137 to a minimum, ease of parting is achieved. Tapering the cylindrical body member 71 at 78 further facilitates in manipulation of the horn engaging member 35 and also facilitates parting of the horn bud from the skull. Additionally, tapering the cylindrical body member 71 at 78 also facilitates cauterising of any ruptured blood vessels in the animal's head resulting from the removal of the horn bud. It has also been found that by providing a horn engaging recess 75 of hemispherical shape new and surprising results are achieved, particularly, effective and efficient operation of the dehorning tool 1 is achieved. It is believed that by providing the hemispherical recess to be a good fit over the horn bud good heat transfer to the horn bud is achieved, and also scooping of the horn bud from the animal's skull is facilitated.

A bore 138 extends through the cylindrical body member 71 into the horn engaging recess 75 adjacent a base 139 thereof for accommodating a rod (not shown) for disengaging and discharging residual horn debris from the recess 75.

Referring now to Fig. 4, the control means for vaporising and controlling the rate at which fuel gas is delivered from the reservoir 25 to the combustion chamber 38 will now be described. Portion of the inner housing 12 extends into the reservoir 25 to form an outlet housing 81 which defines an outlet bore 82 from the reservoir 25. A regulator 83 for regulating the flow rate of fuel gas from the reservoir 25 into the main passageway 30 is mounted in the outlet bore 82. The regulator 83 comprises a housing 84 which is pressed into the outlet bore 82. A block 86 of resilient and porous plastics material through which fuel gas passes is mounted in a bore 87 of the housing 84. An adjusting screw 88 engaging a threaded portion 89 of the bore 87 is adjustable into and out of the bore 87 and acts on a rod 85 of brass for compressing and relaxing the block 86 for in turn varying the porosity of the block 86 for regulating the flow rate of fuel gas through the bore 87. The rod 85 is slidable in the outlet bore 82. A shaft 90 connects the adjusting screw 88 to a knob 91 rotatable on the inner housing 12 for adjusting the screw 88. A pair of openings 92 in the outer shell 10 provide finger and thumb access to the knob 91 for adjusting the screw 88. An opening 93 in the knob 91 provides access to the filler valve 27 in the end cap 26 for filling the reservoir 25. The outer shell 10 terminates in an open end 97 to provide access to the filler valve 27.

Fuel gas is delivered through an outlet orifice 94 in the housing 84 from the bore 87 into the main passageway 30. A valving member 95 of plastics material is slidable in the main passageway 30, and carries a sealing member 96 for selectively closing the outlet orifice 94 for isolating the reservoir 25 from the main passageway 30. The valving member 95 is slidable in the direction of the arrow A from an open position with the sealing member 96 spaced apart from the housing 84 with the outlet orifice 94 open, to a closed position with the sealing member 96 engaging the housing 84 for closing the outlet orifice 94. The valving member 95 is slidable in the direction of the arrow B from the closed to the open position.

A carrier member 98 of plastics material is rigidly connected to the valving member 95 and is longitudinally slidable with the valving member 95 in the main passageway 30. A camming member

100 is rotatable and longitudinally slidable in a portion 101 of the main passageway 30. The camming member 10 co-operates with a camming surface 102 formed in the inner housing 12 in the portion

101 the main passageway 30 and a shoulder 104 on the carrier member 98 for sliding the valving member 95 and the carrier member 98 in the direction of the arrows A and B. A thumb operated slider 106 is slidable in the inner housing 12 in the direction of the arrows C and D, and is engageable with a projection 107 on the camming member 100 for operating the camming member 100 for sliding the valving member 95 and the carrier member 98. The operation of such a thumb operated slider, camming member and valving member and carrier member are described in European Specification No. EP-A-0118282. An opening 108 in the outer shell 10 accommodates the thumb operated slider 106.

A longitudinally extending bore 110 through the valving member 95 and the carrier member 98 accommodates fuel gas from the outlet orifice 94. A mounting portion 119 extending from the sealing member 96 extends into the longitudinal bore 110 at the upstream end and sealably closes the end of the bore 110 as well as securing the sealing member 96 in engagement with the valving member 95. A transverse bore 111 through the valving member 95 communicating the bore 110 and the main passageway 30 accommodates fuel gas from the main passageway 30 into the bore 110. An 0-ring seal 112 in an annular groove 114 around the valving member 95 prevents the passage of fuel gas along the main passageway 30 downstream of the transverse bore 111. A filter 115 in the longitudinal bore 110 filters the fuel gas through the longitudinal bore 110. The carrier member 100 rigidly carries a jet housing 116 at its downstream end. A bore 117 communicating with the longitudinal bore 110 of the carrier member 98 extends through the jet housing 116 and terminates in a jet orifice 118 for delivering the fuel gas in gaseous form.

A heat conducting means comprising a heat conducting member 120 of heat conductive material, namely, brass is slidable longitudinally in the inner pipe 41. of the gas supply pipe 40 and forms a relatively tight sliding fit with the inner pipe 41 for conducting heat from the combustion chamber 38. The heat conducting member 120 rigidly engages the jet housing 116 with heat conducting engagement for conducting heat from the combustion chamber 38 into the jet housing 116 to prevent the fuel gas passing through the jet orifice 118 freezing. The heat conducting member 120 being rigidly connected to the jet housing 116 is in turn rigidly connected to the carrier member 98 and in turn the valving member 95, and is slidable together with the carrier member 98 and the valving member 95. Heat from the heat conducting member 120 is also conducted through the carrier member 98 and the valving member 95 to minimize the risk of freezing of fuel gas through the outlet orifice 94. A compression spring 124 acting between a flange 125 on the inner pipe 41 and a shoulder 126 on the heat conducting member 120 biases the heat conducting member 120 and in turn the carrier member 98 and valving member 95 in the direction of the arrow A for biasing the sealing member 96 into the closed position. Accordingly, on the thumb operated slider 106 being moved in the direction of the arrow D for closing the outlet orifice 94, on the sealing member 96 engaging the housing 84, the spring 124 assists in retaining the sealing member 96 in the closed position closing the outlet orifice 94.

A bore 127 extending through the heat conducting member 120 accommodates fuel gas from the jet orifice 118 into the inner pipe 41 for delivery to the combustion chamber 38. A pair of opposite radial bores 129 through the heat conducting member 120 adjacent the jet housing 116 delivers air into the bore 127. A venturi throat 130 for mixing air from the bores 129 with fuel gas from the jet orifice 118 for delivery to the combustion chamber 38 is formed in the bore 127 adjacent the jet housing 116. A cavity 133 in the mounting flange 15 communicates with atmosphere through an opening 134 for providing air to the radial bores 129.

In use, when it is desired to dehorn an animal, the dehorning tool element 6 is connected to the handle 2 by securing the connecting flange 54 tα the receiving flange 22 and to the mounting flange 15 with the screws 55. The thumb operated slider 106 is moved in the direction of the arrow D thus permitting fuel gas to flow through the outlet orifice 94 from the reservoir 25 into the main passageway 30. The fuel gas flows through the transverse bore 111 into the longitudinal bore 110 from which it is delivered in gaseous form through the jet orifice 118. Air is mixed with the fuel gas in the venturi throat 130 of the bore 127 which is in turn delivered into the combustion chamber 38 and through the gas catalytic combustion element 57. The outer shield 65 is slid into the open position to expose the primary exhaust outlets 56. Gas exiting through one of the primary exhaust outlets 56 is ignited with a flint spark, a naked flame or any other suitable ignition means. The gas burns for a short period of time in the primary exhaust outlet 56 until the temperature of the gas catalytic combustion element 57 adjacent the primary exhaust outlet 56 is raised to its ignition temperature. At which stage the gas catalytic combustion element 57 commences to convert the gas to heat. The rest of the combustion element 57 rapidly rises to ignition temperature, and the flame in the primary exhaust outlet 56 extinguishes. The outer shield is then slid into the closed position thus shielding the primary exhaust outlet 56.

When the horn engaging member 35 is at a suitable working temperature, in this case, approximately 500°C to 600°C, the handle 2 is gripped around the outer shell 10 by hand, and the horn engaging recess 75 is engaged on the horn bud of a calf, heifer, bullock or any other animal. The tool 1 is then manipulated so that the horn bud is scooped from the skull of the animal by the horn engaging member 35. The scooping action of the horn engaging element on the horn bud causes the rim 137 of the horn engaging end 76 to part the horn bud from the skull. As the bud is being scooped from the skull of the animal the tapered surface 78 of the hot horn engaging member 35 cauterises any blood vessels ruptured in scooping the horn bud from the animal's skull.

Alternatively, with the horn engaging member 35 at approximately 500°C to 600°C, the horn bud may be engaged by the horn engaging recess for ten to fifteen seconds, and then disengaged from the horn bud. It is believed that in this time period the horn cells are destroyed, and in due course, the horn bud is rejected by the animal and drops off. To enhance the destruction of the cells in the horn bud, while the horn engaging member is in engagement with the horn bud, the handle 35 may be alternately rotated in a clockwise and anti-clockwise direction to thereby rotate the horn engaging member 35 on the horn bud.

It has been found that by providing the outer shield around the combustion chamber housing heat loss from the combustion chamber housing is significantly reduced, to the extent that the dehorning tool may be used in the open air with a relatively strong breeze blowing and sufficient heat is conducted into the horn engaging member for carrying out the dehorning operation effectively and efficiently. Furthermore, it has been found that the provision of the outer shield around the combustion chamber housing avoids the danger of a strong breeze acting on the primary exhaust outlets which would either extinguish the catalytic combustion element or cause gas slippage through the catalytic combustion element, which would in turn significantly reduce the gas to heat conversion efficiency of the catalytic combustion element.

It has been found that the horn engaging member heats to its working temperature of approximately 600°C in approximately six minutes from cold. The time taken to remove a horn bud using the tool is approximately ten to fifteen seconds. Accordingly, two horn buds of an animal may be removed in approximately twenty to thirty seconds. It has been found that during removal of two horn buds the temperature of the horn engaging member tends to drop by about 200°C and the recovery time for the horn engaging member to a temperature of 500°C to 600°C is approximately two minutes. Power output of the heating tool is approximately 100 to 150 Watts.

Referring now to Fig. 13 the soldering tool element 7 will now be described. The soldering tool element 7 is substantially similar to the dehorning tool element 6, and similar components are identified by the same reference numerals. The main difference between the soldering tool element 7 and the dehorning tool element 6 is that the horn engaging member 35 is replaced by a soldering body member 140. The soldering body member 140 is of solid copper nickel plated and terminates in a soldering tip portion 141. The combustion chamber housing 36 is formed by a tubular member 37 extending rearwardly from the soldering body member 140 which is machined integrally with the soldering body member 140. Otherwise, the soldering tool element 7 is similar to the dehorning tool element 6.

To connect the soldering tool element 7 to the handle 2, the heat conducting member 120 extending from the jet housing in the handle 2 is inserted into the inner pipe 41 of the gas supply pipe 40. The connecting flange 54 of the soldering tool element 7 is brought into engagement with the receiving flange 22 and secured to the receiving flange 54 and the mounting flange 15 by the screws 55. Ignition of the soldering tool element 7 is identical to the steps which are carried out for ignition of the dehorning tool element 6.

Referring now to Fig. 14 the heated knife tool element 8 is illustrated. The heated knife tool element is substantially similar to the dehorning tool element 6 and similar components are identified by the same reference numerals. The main difference between the heated knife tool element 8 and the dehorning tool element 6 is that the horn engaging member 35 is replaced by a body member 145 of solid copper nickel plated from which a knife blade 146 also of solid copper nickel plated extends forwardly. A combustion chamber housing 36 identical to the combustion chamber housing 36 of the dehorning tool element 6 extends rearwardly of the body member 145. The body member 145, the knife blade 146 and the combustion chamber housing 36 are integrally formed.

Connection of the heated knife tool element 8 to the handle 2 is similar to connection of the soldering tool element 7 to the handle 2. The heat conducting member 120 extending from the jet housing 116 in the handle 2 is inserted in the inner pipe 41 of the gas supply 40 of the tool element 8. The connecting flange 54 of the tool element 8 is secured to the receiving flange 22 and the mounting flange 15 of the handle 2 by the screws 55.

Alternatively, if desired, instead of replacing the dehorning tool element 6 by the soldering tool element 7 or the heated knife element 8, only the horn engaging member 35 may be replaced by the soldering body member 140 or the body member 145 of the heated knife tool element 8. In which case, the screw 51 is released from the horn engaging member 35 and the horn engaging member 35 is disengaged from the sleeve 45. The appropriate body member 140 or 145 is engaged in the sleeve 45 with the openings 61 in the combustion chamber housing 36 aligned with the openings 68 of the sleeve 45 to form the primary exhaust outlets 56. The appropriate body member 140 or 145 is then secured in the sleeve 45 by the screw 51. It is envisaged that in certain cases where the horn engaging member 35 and the body members 140 and 145 are interchangeable in the sleeve 45, that the horn engaging member 35 and body members 140 and 145 will be supplied with the catalytic combustion element in the combustion chamber and secured therein by the pin 60.

Needless to say, other types of heating tool elements may be provided.

Referring now to Fig. 15, there is illustrated a soldering tool element according to another embodiment of the invention indicated generally by the reference numeral 150. The soldering tool element 150 is substantially similar to the soldering tool element 7 and similar components are identified by the same reference numerals. The main difference between the soldering tool element 150 and the soldering tool element 7 is in the construction of the gas supply pipe 151 and the outer shield 152. In this embodiment of the invention the sleeve 45 extends rearwardly of the combustion chamber housing 36 to form the gas supply pipe 151. The gas supply pipe 151 carries the connecting flange 54 which is welded to the fuel supply pipe 151. The outer shield 152 is welded to a flange 153 which spaces the outer shield 152 apart from the sleeve 45 to form the exhaust gas chamber 69. The other end of the outer shield 152 slidably engages an annular portion 154 of reduced outer diameter which extends from the securing ring 46 around the sleeve 45. When the outer shield 152 is in the first position illustrated in Fig. 15, the flange 153 together with the annular portion 154, the sleeve 45 and the outer shield 152 form the exhaust gas chamber 69. The compression spring 72 acts between the connecting flange 54 and the flange 153 in similar fashion as the compression spring 72 acts between the connecting flange 54 and the flange 73 of the soldering tool tip 7.

In this embodiment of the invention the heat conducting member 120 extending from the jet housing 116 in the handle 2 extends into the gas supply pipe 151 to a position adjacent the gas inlet 39 to the combustion chamber 38 for conducting heat from the combustion chamber 38 to the jet housing 116. The heat conducting member 120 does not engage the gas supply pipe 151. The heat conducting spigot 63 is omitted from the combustion chamber 38 in the soldering tip 150.

Operation of the soldering tool element 150 is similar to that of the soldering tool element 7. The soldering tool element 150 is connected to the handle by engaging the connecting flange 54 with the receiving flange 22 and securing the connecting flange 54, the receiving flange 22 and the mounting flange 15 with the screws 55.

Referring now to Fig. 16, there is illustrated a dehorning tool element according to another embodiment of the invention indicated generally by the reference numeral 170. The solderinf tool element 170 is illustrated connected to the receiving flange 22 and the mounting flange 15 of the dehorning tool of Figs. 1 to 12. The handle which is identical to the handle 2 of the dehorning tool 1 is not illustrated. The dehorning tool element 170 is substantially similar to the dehorning tool element 6 and similar components are identified by the same reference numerals. The main difference between the dehorning tool element 170 and dehorning tool element 6 is in the construction of the gas supply pipe 40. In this embodiment of the invention, the sleeve 45 extends rearwardly of the combustion chamber housing 36 to form a gas supply pipe 173. The gas supply pipe 173 extends to the connecting flange 54 and is welded thereto. An annular spacer 174 of a high temperature plastics material having a spigot portion 175 extending therefrom engages a bore 178 of the gas supply pipe 173. A shoulder 179 extending round the spacer 174 engages the connecting flange 54 so that the spacer 174 can act as an abutment for the compression spring 124. A bore 180 extending through the spacer 174 slidably engages and guides the heat conducting member 120 into the bore 178 of the gas supply pipe 173. A tube 181 of stainless steel and circular cross- section is rigidly engaged in and extends from the bore 127 of the heat conducting member 120 towards the combustion chamber 38 for conducting heat therefrom into the heat conducting member

120, and in turn into the jet housing 116 to prevent freezing of fuel gas. A baffle disc 182 of brass extends around the tube 181 and slidably engages the bore 178 of the gas supply pipe 173 for guiding the tube 181 in the gas supply pipe 173. The tube 181 is secured in the baffle disc 182 by crimping into an annular recess 183 extending around a bore 184 in the baffle disc 182. Otherwise the dehorning tool element 170 is similar to the dehorning tool element 6. Use of the dehorning tool element 170 is also similar to use of the dehorning tool element 6. As the valving member 95 and the carrier member 98 are moved in the direction of the arrow D to open the outlet orifice 94 the heat conducting member 120 and the tube 181 slide in the gas supply pipe 173 towards the combustion chamber 38 for conducting heat from the combustion chamber 38 to the jet housing 116 and in turn the carrier member 98 and the valving member 95. While the heating tool has been described in the form of a dehorning tool having a dehorning tool element with an outer shield, in certain cases, it is envisaged that the dehorning tool element may be provided without the outer shield.

It is also envisaged that while it is preferable it is not essential that the tool element be provided with a fuel gas reservoir in the handle, and in cases where a fuel gas reservoir is provided, it is not essential that the fuel gas reservoir be refiliable. It will of course be appreciated that other control means for delivering fuel gas to the combustion chamber may be provided besides those described.

Further, it is envisaged in certain cases that the heat transfer means for transferring heat from the combustion chamber to the jet housing may be dispensed with.

It is envisaged that while the horn engaging recess has been described as being of hemispherical shape, a horn engaging recess of other shapes may be provided, and indeed, other suitable horn engaging means may be provided.

While the combustion chamber housing has been described as being of a particular shape, other suitable shapes of combustion chamber housing may be provided. Further, it will be appreciated that it is not essential that the combustion chamber housing be formed integrally with the working body member. It will also be appreciated that other suitable means for connecting the combustion chamber housing to the handle besides those described may be provided.

While the material of the working body member has been described as being nickel plated copper, the working body member may be of any other suitable material, as indeed the combustion chamber may also be of other suitable material. It is also envisaged in certain cases that the heat conducting member may be of a relatively high temperature plastics material with reasonably good heat conducting characteristics.

While a single porous member has been described in the regulator for regulating the gas flow from the reservoir, any number of porous members may be provided.

It is also envisaged that a hot air blower working body member may be provided which could replace the dehorning element, soldering tool element and heating knife. Needless to say, any other desirable working body members may be provided.

Claims

1. A gas powered heating tool element (4,6,7,8,9,170) comprising a working body member (35,140,145) of heat conductive material, a hollow combustion chamber housing (36) extending from the working body member (35,140,145) forming a combustion chamber (38) for combusting gas therein, the combustion chamber housing (36) being of heat conductive material and being in heat conducting engagement with the working body member (35,140,145), a gas inlet (39) being provided to the combustion chamber (38), a primary exhaust outlet (56) being provided from the combustion chamber (38) for exhausting gas from the combustion chamber (38), characterised in that an outer shield (65) extends around the combustion chamber housing (36) and over the primary exhaust outlet (56) for shielding the combustion chamber housing (36) for minimizing heat loss from the combustion chamber housing (36), the shield (65) defining with the combustion chamber housing (36) an exhaust gas chamber (69) communicating with the combustion chamber (38) through the primary exhaust outlet (56), and at least one secondary exhaust outlet (70) being provided from the exhaust gas chamber (69) for exhausting exhaust gas from the exhaust gas chamber (69).

2. A heating tool element as claimed in Claim 1 characterised in that the primary exhaust outlet (56) and the secondary exhaust outlet (70) are staggered relative to each other for retarding the passage of exhaust gas through the exhaust gas chamber (69).

3. A heating tool element as claimed in Claim 1 or 2 characterised in that the outer shield (65) extends completely around the combustion chamber housing (36) and defines therewith an annular exhaust gas chamber (69).

4. A heating tool element as claimed in any preceding claim characterised in that the outer shield (65) is movable from a first position shielding the primary exhaust outlet (56) to a second position with the primary exhaust outlet (56) exposed.

5. A heating tool element as claimed in Claim 4 characterised in that the combustion chamber housing (36) comprises an elongated combustion chamber housing (37), the outer shield (65) being axially slidable longitudinally along the combustion chamber housing (36) between the first and second positions.

6. A heating tool element as claimed in Claim 4 or 5 characterised in that biasing means (72) is provided for urging the outer shield (65) into the first position.

7. A heating tool element as claimed in Claim 6 characterised in that the biasing means (72) comprises a compression spring (72).

8. A heating tool element as claimed in any preceding claimed characterised in that the combustion chamber housing (36) comprises an elongated tubular member (37) extending rearwardly from the working body member (35).

9. A heating tool element as claimed in Claim 8 characterised in that the combustion chamber housing (36) terminates in the gas inlet (39), the primary exhaust outlet (56) extending radially through the combustion chamber housing (37) downstream of the gas inlet (39).

10. A heating tool element as claimed in Claim 8 or 9 characterised in that the tubular member (37) forming the combustion chamber housing (36) is of circular transverse cross- section.

11. A heating tool element as claimed in any preceding claim characterised in that the gas inlet (39) is provided remote of the working body member (35), the primary exhaust outlet (56) being provided adjacent the working body member (35), and each secondary exhaust outlet (70) being provided remote of the working body member (35).

12. A heating tool element as claimed in any preceding claim characterised in that a gas catalytic combustion heating element (57) is provided in the combustion chamber (38).

13. A heating tool element as claimed in Claim 12 characterised in that the catalytic combustion element (57) is of annular shape defining a through bore (59) communicating with the gas inlet

(39) and being gas permeable to facilitate radial passage of gas therethrough to the primary exhaust outlet (56).

14. A heating tool element as claimed in Claim 12 or 13 characterised in that the catalytic combustion element (57) comprises a carrier (58) of pierced stainless steel sheet material.

15. A heating tool element as claimed in any preceding claim characterised in that connecting means (54) are provided for connecting the heating tool element (4) to a handle (2) and to a gas supply means.

16. A heating tool element as claimed in Claim 15 characterised in that the connecting means (54) comprises a gas supply pipe

(40) extending from the gas inlet (39).

17. A heating tool element as claimed in Claim 16 characterised in that the gas supply pipe (40) extends axially longitudinally from the combustion chamber housing (36).

18. A heating tool element as claimed in any of Claims 15 to 17 characterised in that the connecting means (54) is releasably connectable to the handle (2).

19. A heating tool element as claimed in any of Claims 15 to 18 characterised in that the working body member (35) is releasably engageable with the connecting means (54).

20. A heating tool element as claimed in any preceding claim characterised in that the combustion chamber housing (36) is integrally formed with the working body member (35).

21. A heating tool element as claimed in any preceding claim characterised in that the working body member (35) forms any one of the following: a soldering tip (7,9), a horn engaging element (6,160) for dehorning an animal, a heated knife (8), and a hot air blower.

22. A heating tool comprising a handle (2) formed by an elongated handle housing (3), a fuel supply means (25,116) being provided in the handle housing (3), characterised in that a heating tool element (4) as claimed in any preceding claim is connected to the handle housing (3).

23. A heating tool as claimed in Claim 22 characterised in that a heat conducting means (120) extends from the heating tool element (4) to the fuel supply means (116) through the connecting means (54) for transferring heat from the combustion chamber (38) to the fuel supply means (116) for preventing freezing of the fuel.

24. A heating tool as claimed in Claim 22 or 23 characterised in that the fuel supply means (25,116) comprises a jet housing (116) having a jet orifice (118) extending therethrough, the heat conducting means (120) being in heat conducting engagement with the jet housing (116).

25. A dehorning tool element (6,170) comprising a working body member (35) of heat conductive material, the working body member having horn engaging means (75) formed therein, a hollow combustion chamber housing (36) extending from the working body member (35) forming a combustion chamber (38) for combusting gas, the combustion chamber housing (36) being of heat conductive material and being in heat conducting engagement with the working body member (35), a gas inlet (39) being provided to the combustion chamber (38), a primary exhaust outlet (56) being provided from the combustion chamber (38) for exhausting gas from the combustion chamber (38).

26. A dehorning tool element as claimed in Claim 25 characterised in that the horn engaging means (75) is formed by a horn engaging recess (75) extending into the working body member (35).

27. A dehorning tool element as claimed in Claim 26 characterised in that the working body member (35) is formed by a cylindrical horn engaging body member (71) having an outer cylindrical surface (74) and terminating at one end in a horn engaging end (76), the horn engaging recess (75) extending into the horn engaging body member (71) from the horn engaging end (76).

28. A dehorning tool element as claimed in Claim 27 characterised in that the horn engaging recess (75) extends axially into the horn engaging body member (71).

29. A dehorning tool element as claimed in Claim 27 or 28 characterised in that the geometrical axis of the horn engaging recess (75) coincides with the geometrical axis of the horn engaging body member (71).

30. A dehorning tool element as claimed in any of Claims 27 to 29 characterised in that the outer cylindrical surface (74) of the horn engaging body member (78) tapers towards the horn engaging end (76) adjacent the horn engaging end (76).

31. A dehorning tool element as claimed in any of Claims 27 to 30 characterised in that the combustion chamber housing (36) is an elongated housing (37) extending longitudinally rearwardly from the end (77) of the horn engaging body member (71) remote from the horn engaging end (76).

32. A dehorning tool element as claimed in Claim 31 characterised in that the geometrical axis of the combustion chamber housing (36) coincides with the geometrical axis of the horn engaging body member (71).

33. A dehorning tool element as claimed in any of Claims 26 to 32 characterised in that the horn engaging recess (75) is of partly spherical shape.

34. A dehorning tool element as claimed in Claim 33 characterised in that the horn engaging recess (75) is of hemispherical shape.

35. A dehorning tool element as claimed in any of Claims 26 to 34 characterised in that a bore (138) extends through the working body member (35) terminating in the horn engaging recess (75) for facilitating removal of horn debris from the horn engaging recess (75).

36. A dehorning tool element as claimed in any of Claims 25 to 35 characterised in that the combustion chamber housing (36) is of circular cross-section.

37. A dehorning tool element as claimed in any of Claims 25 to 36 characterised in that the working body member (35) is of solid construction.

38. A dehorning tool (1) comprising a handle (2), a dehorning tool element (6,170) connected to the handle (2) by a connecting means (54), the dehorning tool element (6,170) being according to any of Claims 25 to 37.