A welder for a robot

Abstract

A welder 40 comprises a connector 41 for connection to a robot; a welding torch 42 having a principal axis 42a; and a wire feed guide 55 which can rotate about the principal axis 42a of the welding to

Description

FIELD OF THE DISCLOSURE The present disclosure concerns a welder for a robot. Specifically, it concerns a welder for robotic gas metal arc welding. BACKGROUND In recent years progress has been made in the development of robotic welding techniques. For example, robotic welding is now commonplace within the automotive industry, bringing improvements is weld repeatability and reduced manufacturing costs. However, the successful uptake of robotic welding is dependent upon the overall geometric complexity of the structure to be welded, in which robotic welding is more common for applications in which there is good access for the robot welder. It is therefore desirable to develop a welder for a robot that is suitable for use where access is reduced. SUMMARY According to a first aspect there is provided a welder for a robot. The welder comprises a connector for connecting the welder to the robot and a welding torch that has a principal axis and is connected to the connector. The welder additionally comprises a motor and a wire feed guide that is configured to guide a welding wire to extend towards the principal axis of the welding torch. The wire feed guide is rotatable by the motor about the principal axis of the welding torch. The welding torch may be selected from one of a tungsten inert gas welding torch, a laser welding torch, an oxy-acetylene welding torch. The principal axis of the welding torch may be offset from a rotational axis of the robot to which the welder is connected. The rotational axis of the robot may be a rotational axis of a wrist of the robot. The principal axis of the welding torch may be inclined relative to the rotational axis of the robot to which the welder is connected. The rotational axis of the robot may be a rotational axis of a wrist of the robot. The wire-feeding guide may be connected to the motor via a gear-train. The wire feed guide may be rotated in dependence upon a defined weld path. The motor may be controlled by a motor controller. The motor controller may be part of a controller of the robot or may interface with the controller of the robot. The robot disclosed in the preceding paragraphs may be a six-axis robot. According to a second aspect there is provided a method of welding using a welder for a robot. The method comprises defining a weld path along a surface of a component to be welded and welding the component by moving welding torch along the defined path. A welding wire feed guide to the welding torch is rotatable about a principal axis of the torch of the welder and is rotatably independent of movement of the welding torch along the welding path by the robot. The welding torch used in the above method may be selected from one of a tungsten inert gas welding torch, a laser welding torch, an oxy-acetylene welding torch The skilled person will appreciate that except where mutually exclusive, a feature described in relation to any one of the above aspects may be applied mutatis mutandis to any other aspect. Furthermore except where mutually exclusive any feature described herein may be applied to any aspect and / or combined with any other feature described herein. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments will now be described by way of example only, with reference to the Figures, in which: FIG. 1 is a sectional side view of a gas turbine engine; FIG. 2 is an illustrator example of a 6-axis robot; FIG 3 illustrates a desired spatial relationship between a welding torch and wire feed guide during welding; FIG 4 provides an example of a known welder for a robot; FIG 5 provides a first example configuration of a welder for a robot FIG 6 provides a second example configuration of a welder for a robot; FIG 7 provides a third example configuration of a welder for a robot; 5 FIG 8 provides a first example motor arrangement of a welder for a robot; FIG 9 provides a second example motor arrangement of a welder for a robot; and FIG 10 provides a third example motor arrangement of a welder for a robot. The following table lists the reference numerals used in the drawings with the features to which they refer: Ref no. Feature FIG. 10 Gas turbine engine 1 11 Principal and rotational axis (of engine) 1 12 Air intake 1 13 Fan 1 14 Intermediate pressure compressor 1 15 High pressure compressor 1 16 Combustion equipment 1 17 High pressure turbine 1 18 Intermediate pressure turbine 1 19 Low pressure turbine 1 20 Exhaust nozzle 1 21 Nacelle 1 22 Bypass duct 1 30 Robot 2 31a - 31f Joint of Robot 2 32a-32f Axis of Rotation of Robot Joint 2 35 Interface (between robot and robot welder) 2 40 Welder 2 41 Connector 2 42 Torch of welder 2 42a Principal axis of Torch 3-10 44 Shield 8 9 10 Ref no. Feature FIG. 50 Weld bead 3 51 Weld path 3 52 Electrode 38 9 10 52a Principal axis of Electrode 38 9 10 53 Electric Arc 3 54 Welding Wire 3-7 55 Wire Feed Guide 4-10 56 Motor 8, 9, 10 57 Geartrain 9 57a Motor gear 9 57b Second gear 9 58 Inert gas 3 59 Arm 8-10 60 Substrate 3 DETAILED DESCRIPTION Although the following disclosure is made in relation to the welding of components of a gas turbine engine 10, it will be appreciated that the disclosure is equally applicable to the welding of any component, particularly components which have a complex geometry. Aspects and embodiments of the present disclosure will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. With reference to FIG. 1, a gas turbine engine is generally indicated at 10, having a principal and rotational axis 11. The engine 10 comprises, in axial flow series, an air intake 12, a propulsive fan 13, an intermediate pressure compressor 14, a high-pressure compressor 15, combustion equipment 16, a high-pressure turbine 17, an intermediate pressure turbine 18, a low-pressure turbine 19 and an exhaust nozzle 20. A nacelle 21 generally surrounds the engine 10 and defines both the intake 12 and the exhaust nozzle 20. The gas turbine engine 10 works in the conventional manner so that air entering the intake 12 is accelerated by the fan 13 to produce two air flows: a first air flow into the intermediate pressure compressor 14 and a second airflow which passes through a bypass duct 22 to provide propulsive thrust. The intermediate pressure compressor 14 compresses the airflow directed into it before delivering that air to the high pressure compressor 15 where further compression takes place. The compressed air exhausted from the high-pressure compressor 15 is directed into the combustion equipment 16 where it is mixed with fuel and the mixture combusted. The resultant hot combustion products then expand through, and thereby drive the high, intermediate and low-pressure turbines 17, 18, 19 before being exhausted through the nozzle 20 to provide additional propulsive thrust. The high 17, intermediate 18 and low 19 pressure turbines drive respectively the high pressure compressor 15, intermediate pressure compressor 14 and fan 13, each by suitable interconnecting shaft. Other gas turbine engines to which the present disclosure may be applied may have alternative configurations. By way of example such engines may have an alternative number of interconnecting shafts (e.g. two) and / or an alternative number of compressors and / or turbines. Further the engine may comprise a gearbox provided in the drive train from a turbine to a compressor and / or fan. The above description of a gas turbine engine 10 is written largely in functional terms. However, to enable the gas turbine engine to function, it will also be appreciated that a gas turbine engine 10 additionally comprises structural features to secure or locate functional features (e.g., such as a compressor) relative to each other and / or such that that the gas turbine engine 10 may be connected to another device for example, an aircraft. Due to the nature of design of the gas turbine engine 10, these structural components may have complex shapes. For example a casing may be located between the intermediate pressure compressor and the high pressure compressor. This type of casing may also be referred to as an “intercase”. This casing may have multiple requirements. For example, although the intercase may provide structural support, it may also comprise an aerodynamic duct linking the intermediate and high pressure compressors. The aerodynamic duct may also comprise at least one aerodynamic offtake for extracting compressor air for another component or system of the gas turbine engine. Although such a structural component may be manufactured from a single casting, the complexity of the component and / or the long lead-times associated with obtaining a fully cast structural component, may encourage the skilled person to at least partially fabricate the structural component from a number of smaller components. The structural component (e.g., the intercase) may then be formed by welding these smaller components together. Alternatively or additionally, even if formed from a single casting, some form of weld repair may be desirable, if a crack is detected in the casting. It will be readily appreciated that the advantages of robotic welding (for example, reduced variability in weld quality) make it desirable to use a robotic welder when fabricating or repairing such a component, if possible. It may be desirable to use a robot fitted with a welder (a robot welding head) that has the ability to form a continuous weld bead (a continuous weld seam), as opposed to a spot welder. This is because joining via a continuous weld bead may produce a more rigid structure than joining via a series of spot welds. Joining via a continuous weld bead may also enable adjacent sections of the welded structure to form independent, non-interconnected volumes or cavities from each other, whereas some leakage between adjacent sections may occur between spotweld locations. Examples of a welder capable of forming a continuous weld bead include a gas metal arc welder such as a Tungsten Inert Gas (TIG) welder, a laser welder and an oxy-acetylene welder. It will also be readily appreciated that use of a welder capable of forming a continuous weld bead, may, if required, produce a series of discrete welds where it is appropriate to do so. FIG. 2 provides an example illustration of a robot that may be suitable for robotic welding. The example robot 30 of FIG. 2 has 6 axes of freedom and may also be referred to as a 6-axis robot. The robot comprises a plurality of rotatable joints 31a, 31b, 31c, 31 d, 31 e, 31 f, each joint having its own respective axis of rotation 32a, 32b, 32c, 32d, 32e, 32f, and each joint corresponding to one of the axes of freedom of the robot. Other types of robot, having alternate designs and alternate numbers of axes of rotation are also available. The robot 30 comprises an interface 35, as for example, an interface plane 35, to which a tool 40 may be connected. A welding tool (welder) 40 such as a gas metal arc welder 40 or a laser welder 40 or an oxy-acetylene welder is an example of a tool 40. By controlling rotation of rotatable joints 31, the location and orientation of interface 35 may be controlled in three-dimensional space, and consequently, the location and orientation of a tool 40 that is connected to the robot 30 at interface 35 may also be controlled in three-dimensional space. This is desirable when using the robot 30 for welding, as may be better understood with reference to FIG. 3. In the example of FIG. 3, a weld bead 50 is to be produced along a weld path 51 on a substrate 60. Substrate 60 forms part of a component that is to be welded. The weld bead 50 may be a continuous weld (as shown in FIG. 3) bead or may be a discontinuous weld bead that approximates to a series of adjacent spot welds. The weld bead is produced via a welder of a known type. For example, the welder may be a laser welder or an oxy-acetylene welder, although in the example of FIG 3, the welder is a Tungsten Inert Gas (TIG) welder. The above types of welder may have a feature in common, namely use of separate welding wire, supplied by a welding wire feed guide at an angle a to a welding torch. The value of a may vary with the type of welder used or material to be welded. Although the remainder of this document discloses features of the welding wire feed guide in relation to a TIG welder, it will be understood that the features are equally applicable to other welder types such as an oxy-acetylene welder or laser welder. In FIG. 3, the TIG welder 40 comprises a torch 42, having a principal axis 42a. The torch 42 comprises an electrode 52 made from tungsten. The electrode 52 has a principal axis 52a, aligned along the length of the electrode 52. In the example of FIG. 3, principal axes 42a and 52a are coaxial. In use, a flow of an inert gas 58 surrounds the electrode 52 to protect it from the surrounding atmosphere, while an electrical connection (not shown) is made between electrode 52 and substrate 60 to form a high temperature electric arc 53 between the electrode 52 and the substrate 60. FIG 3. also shows that weld 50 is formed by introducing welding material, in the form of welding wire 54 to electric arc 53. The welding wire 54 is introduced at an angle a to the principal axis 42a of the torch 42 and the principal axis 52a of the electrode 52; i.e., the welding wire 42 extends towards principal axes 42a, 52a and is inclined at an angle a to the principal axes 42a, 52a. The angle of inclination is acute (less than 90°). The quality of the weld 50 formed is improved if the welding wire 54 leads the torch 42 comprising electrode 52 along the resulting welding path 51. In other words, it is desirable that the welding wire 54 is orientated and located in front of the electrode 52 of the torch as the weld bead 50 is produced. It is therefore desirable that a supply of the welding wire 54 moves with electrode 52 over a surface of the substrate 60 as the weld 50 is made. When welding a complex geometry, such as, a gas turbine engine intercase or other structural casing, it may be beneficial to take advantage of the number of axes of freedom of the robot 30 to suitably orientate the welding tool 40. This is because the required weld bead 50 may not follow a linear path, while access of the welder to the substrate 60 may vary along the weld path 51, due to potential clashes between the welder and the component to be welded. As is now explained with reference to FIGS 4 -7, the design of the welder 40 may affect the ease with which a complex geometry component is welded. In FIGS 4-7, details of the torch 42 such as electrode 52 and the in-use protective flow of inert gas 58 are not shown, for ease of reference. FIGS. 4 -7 illustrates different configurations for how a welder 40 may be connected at interface 35 to robot 30. In the examples of FIGS. 4 - 7, the robot comprises an axis of rotation 32f, in which relative motion between components of the robot occurs at joint 31f. In these examples, joint 31f forms at least part of a “wrist” joint of robot 30. FIG. 4 represents a known baseline, of a welder 40 that is connectable to a robot 30, in which the orientation of components of the welder 40 are fixed relative to each other. In FIG 4, torch 42, having principal axis 42a is fed with welding wire 54 through wire feed guide 55. As in FIG. 3, welding wire 54 is supplied laterally offset from torch 42 but extends towards the principal axis 42a of torch 42 in the vicinity of a tip of the torch 42. In this way, the tip of the welding wire 54 is in the vicinity of an electrical arc formed between the electrode of the torch and the substrate to the welded. In the example of FIG 4, it will be appreciated that the welding wire 54 may lead torch 42 when forming a weld bead by rotation of the joints of the robot, and in particular, by rotating joint 31 f of the wrist of robot 30 about axis 32f. However, the inventors have realised that this may not be desirable or possible in all cases as welder 40 requires various supplies to function. For example, the TIG welder of FIG 4 requires a supply of welding wire 54, a supply of inert gas to shield the electrode 52 and an electrical supply to the electrode (not shown), while, as an alternative, an oxy-acetylene welder requires supplies of oxygen gas and acetylene gas. Supplies may be supplied via supply conduits such as flexible tubes, hoses or electrical cables. If welder 40 is rigidly connected to the wrist of the robot 30 at interface 35, the desire to minimise affecting the operation of welder 40 by kinking at least one of supply conduits, such that its respective supply is impeded, reduces the degree of rotation of the robot wrist about axis 32f that may practically occur. This is undesirable as it may limit the component geometries or length of continuous weld beads that may be welded by the robot welder. This may be particularly undesirable if the material to be welded is prone to cracking due to thermally-induced stress concentrations, as the desired continuous weld may be replaced by a series of linked, shorter continuous welds. This may increase the degree of thermal cycling (increases and decreases in temperature) during welding, increasing the likelihood of thermally-induced cracking. The inventors have realised that this risk may be at least partially mitigated if the wire feed guide 55 suppling (feeding) welding wire 54 towards the tip of torch 42 is able to rotate about the principal axis 42a of the torch, independently of rotating a wrist joint of a robot. An example of this arrangement is shown in FIG 5. The welder 40 of FIG 5 differs from the welder of FIG 4 in that the wire feed guide 55, and hence welding wire 54, is independently rotatable about torch 42 without requiring rotation of the entire welder 40 by the robot wrist joint 31 f. This introduces an additional degree of freedom of movement for the robotic welder as a whole, meaning that for the same a desired angular rotation of welding wire 54 such that it leads electrode 52 when welding, this may now be achieved by a combination (sum of) rotation of the welder 40 about robot axis 32f and rotation of the wire feed guide 55 about welder torch axis 42a. For the same total rotation of wire feed guide 55, by additionally rotating the wire feed guide 55 about torch 42, as the degree of rotation of robot wrist joint 31 f about axis 32f is reduced, the likelihood of kinking at least one of the supply conduits to the welder 40 is also reduced. Hence, by introducing an independently rotatable wire feed guide 55 to the welder, the welder of FIG 5 can cope with a wider range of changes in component geometries than the welder of FIG. 4, whilst producing a continuous weld bead 50. Furthermore, by being able to independently vary the rotation of the wire feed guide about the torch 42 and the rotation of the welder about the robot wrist (i.e. rotation 32f about joint 31 f), an additional degree of freedom is introduced in how the welding torch 42, and robot wrist may be orientated whilst maintaining the ability of the wire feed guide to lead 42 the torch along a continuous weld path. This may be particularly advantageous when the geometry to be welded is complex, and accessibility for the welder is difficult. Thus, the welder 40 of FIG 5, is a more adaptable tool than the welder of FIG. 4. Although an improvement, the problem of the avoidance of kinking welding supply conduits supplying gas, electricity, welding wire etc, may remain to some extent. Further embodiments, constituting further improvements are therefore envisaged. These example improvements are illustrated in FIGS 6 and 7. FIG 6 is similar to FIG 5 in that the wire feed guide 55 and welding wire 54 is rotatable about torch 42. However, FIG 6 differs from FIG 5 in that the torch 42, and principal axis 42a of torch 42 of FIG 6 is now offset from but parallel to robot rotational axis 32f. This has the advantage that at least a greater portion of a surface of the welder proximal to interface 35 is now exposed, reducing the probability of kinking the supply conduits to the welder, as these supplies may be more easily supplied to the torch 42 via access to the welder via this interfacing surface. This enables improved provision of supplies, such as welding wire 54, gas and I or electricity to the welder. Consequently, the welder 40 of FIG 6 is therefore more adaptable than either of the welder of FIG 5 or the welder of FIG 4 to accommodate a greater degree of rotation about at least one of torch axis 42a or robot wrist axis 32f. The welder 40 of FIG 6 is therefore capable of providing a continuous weld bead over either a greater distance and / or a greater degree of variation in surface profile (topology) of the component or components to be welded. The welder of FIG 6, comprising an independently rotatable wire feed guide 55, has a further advantage over a non-rotatable wire feed guide and torch offset relative to robot rotational axis 32f. This is because, as previously disclosed, if the wire feed guide 55 is not independently rotatable about torch 42, then orientating wire feed guide 55 such that welding wire 54 leads electrode 52 along the welding path 50 as the welding path 50 changes direction requires the entire welder 40 to be rotated, for example, about robot rotation axis 32f. However, as the principal axis 42a of torch 42 is not coaxial with robot axis 32f, then rotation of welder 40 about axis 32f causes a translation in relative three-dimensional space of the torch in a plane perpendicular to axis 32f. Furthermore, if the torch 42 is not perpendicular to the substrate 60 when this rotation occurs, then the tip of the torch is either moved towards or away from the surface of the substrate because of welder rotation about axis 32f. This has the potential to either damage the torch due to a clash with the substrate 60 or to affect the quality of the resulting weld due to an increased separation between the substrate and the torch. It will be appreciated that although this effect can be compensated for, by defining a movement sequence for the robot axes such that the torch 42 follows a desired weld path 51 that makes allowance for relative movement of torch 42 in a plane perpendicular to axis 32f, defining this robot movement sequence is a more complex task that defining a movement sequence for the robot axes such that the torch 42 follows the desired weld path, with the wire feed guide 55 independently rotatable about the principal axis 42a of the torch 42 such that the welding wire 54 leads electrode 52 along a weld bead. This is because if wire feed guide 55 is rotatable about torch axis 42a, the number of robot axes 32 which are required to be simultaneously rotated such that the electrode 52 follows the required path and the wire feed guide leads the torch is reduced. The total number of axes (sum of robot axes and rotational axis 42a) which need to be simultaneously rotated may also be reduced, as rotation of the wire feed guide 55 about axis 42a equates to a translation in a plane that is perpendicular to robot axis 32f. In addition to reducing the complexity of programming the robot for welding, reducing the number of simultaneous rotations about robot axes 32f when moving torch 42 and wire feed guide 55 along a weld path has further advantages. For example, a less complex robot, having a reduced number of axes of rotation may be used than would otherwise be possible. This may have both financial and environmental advantages, as it may permit an existing robot (for example a robot having a reduced number of axes of rotation) to repurposed for welding complex components, saving money and avoiding the environmental impact of producing a new robot and / or scrapping an otherwise serviceable robot. Reducing the number of total rotational joints that are simultaneously rotating may also be advantageous from a technical perspective as the potential for judder (oscillation) in the position or velocity of the torch 42, causing variability in weld quality along the weld bead may also be reduced. This is because rotation of each joint 31 may cause some degree of judder, with the total judder of the torch 42 being related to the total number of joints moving simultaneously. FIG 7 shows a further refinement. In the example of FIG 7, like the example of FIG. 6, the torch 42 is offset from robot rotational axis 32f. However, unlike FIG. 6, principal axis 42a of torch 42 (i.e., the axis about which wire guide feed 55 is rotatable) is now no longer parallel with axis 32f but is instead inclined relative to axis 32f. In some examples of this arrangement, axes 42a and 32f may intersect in the vicinity of the tip of the torch - i.e., in the vicinity of where an electrical arc is formed during TIG welding. Relative to FIG 6, inclining the principal axis 42a of torch 42 may be desirable because it may improve access of the welding tool to the substrate 60 of the component to be welded. Whether this does or does not occur may be largely dependent upon the geometry of the component to be welded. The skilled person may therefore choose between example welding tools 40 of FIGS 6 and 7 as required. Further details of the welding tool 40, comprising an independently rotatable welding feed are now disclosed in FIGS 8-10. The example welders 40 of FIGS 8-10 are applicable to any of the combinations of torch principal axis 42a location and orientation relative to robot rotational axis 32f illustrated in FIGS 5-7. Although the example welders 40 of FIGS 8-10 are disclosed in relation to TIG welders, features relating to the independent rotation of wire feed guide 55 are also applicable to other forms of welder such as a laser welder, an oxy-acetylene welder. FIG. 8 illustrates a welder (welding tool) 40 for a robot 30. The welder 40 comprises a connector 41 that mechanically connects the welder 40 to the robot 30. For example, the connector 41 is connectable to the robot 30 at interface 35 illustrated in FIG. 2. The welder also comprises a welding torch 42, such as a TIG welding torch, that is rigidly connected to connector 41. The welding torch 42 has a principal axis 42a and an electrode 52. Electrode 52 has a principal axis 52a that is aligned along the length of elongate electrode 52. Principal axes 42a and 52a are coaxial. Optionally, a shield 53 surrounds the electrode 52. The shield 53 is open at one end, proximal to the tip of the electrode 52. In use, an inert gas is supplied to the space formed between the shield 53 and electrode 52, the inert gas exiting at the open end of the shield 53. The shield therefore separates the electrode 52 from the surrounding atmosphere, thereby reducing degradation of the electrode in use. The welder 40 additionally comprises a wire feed guide 55. As previously disclosed, the wire feed guide 55 is rotatable around principal axis 42a. The wire feed guide 55 is configured to guide a welding wire (not shown in FIG 8) towards the principal axis 42a such that an intersection is made between the principal axis of the welding torch and the direction of feeding the welding wire. The wire feed guide 55 may be a tube or any other suitable conduit, through which the welding wire is fed towards the electrode 52. The welding wire may be fed through the wire feed guide by a wire feeding mechanism. The wire feeding mechanism may be remote from the wire feed guide (i.e., the wire feed guide may not be comprised within welder 40). The wire feed guide 55 is mounted on an arm 59 that is rotatable about principal axis 42a without rotating connector 41 (i.e. without rotating at least one joint (e.g. joint 32f) of robot 30. In other words the arm, and consequently, the wire feed guide is independently rotatable about principal axis 42a of torch 42. The wire feed guide 55 extends in a first direction from the arm 59, with the welding wire supplied to the wire feed guide 55 via a port that faces a second direction that opposes the first direction, i.e., the welding wire is supplied from “behind” the arm 59 and wire feed guide 55 such that the supplied welding wire first passes through the arm 59 and then along the wire feed guide before extending beyond the wire feed guide towards electrode 52. The wire feed guide 55 and arm to which it is mounted are rotated by a motor 56, such as a stepper motor. The motor 56 is controlled by a motor controller (not shown). The motor controller may form part of the controller of the robot 30 (robot controller) or may be separate to it. The motor controller may interface with the robot controller such that rotation of the wire feed guide may be co-ordinated with movement of the robot. The location and orientation of the electrode 52 and wire feed guide 55 may be controlled by the controller of the robot and the motor controller such that the wire feed guide 55 leads the electrode 52 when welding (see FIG. 3). The wire feed guide and arm are configured such that welding wire may be supplied without kinking the supply of welding wire or clashing with a portion of welder 40 due to rotation of the arm and welding guide about axis 52a. In the example of FIG. 8, a principal axis of the motor 56 is co-axial with the principal axis 42a of the torch 42. This has the advantage that it enables the motor 56 to directly-drive rotation of the wire feed guide about axis 42a, reducing the number of component parts required, as a gear-train is not required to rotate the wire feed guide about axis 52a. An alternative motor configuration for the welder is illustrated in FIG. 9. The wire feed guide 55 of FIG. 9 is positioned and orientated in a similar manner to that of FIG. 8, in that the wire feed guide 55 is rotatable about principal axis 52a by motor 56 that is controlled by a motor controller (not shown). The apparatus of FIG 9 differs from the apparatus of FIG 8 in that the motor 56 is no longer co-axial with principal axis 42a of torch 42 but is now offset from it. The motor 56 is connected to a motor gear 57a that rotates with motor 56. The motor gear 57a engages (meshes with) a second gear 57b that is fixed relative to the torch 42 and is co-axial with principal axis 42a. This form of geartrain may be referred to as a sun: planetary gear arrangement, in which second gear 57b corresponds to a sun gear 57b, and motor gear 57a corresponds to a planetary gear 57a. Thus, rotation of motor 56 rotates planetary gear 57a about the motor axis. As planetary gear 57a engages with fixed sun gear 57b, rotation of motor 56 causes arm 59 to rotate relative to torch 42. In this way, the wire feed guide may be rotated about axis 42a without rotating welder 40 as a whole by rotating the wrist of the robot to which it is connected by connector 41. Relative to FIG 8, this gear arrangement has the advantage that motor 56 may be mounted further away from the wire feed guide 55 (reducing potential clashes). Furthermore, use of gearing may permit motor 56 to be reduced in size and I or power requirement. Motor 56 and / or gear arrangement 57 may be covered by respective protective covers (not shown). It will be appreciated that the gear arrangement 57 merely reflects one arrangement of gears that fall under the scope of this invention. For example, a bevelled gear arrangement may be used such that the axis of rotation of motor 56 may not only be offset to principal axis 42a but may also be inclined relative to principal axis 42a. For example, motor 56 may alternatively be fixed relative to torch 42, with motor 56 connected to a motor gear 57a that meshes with a second gear 57b that is a ring gear that is rotatable about axis 42a, the ring gear 57b being fixedly connected to wire feed guide 55. Other forms of connecting the welder 40 to a robot 40 at an interface 35 are also envisaged. For example, FIG 10 illustrates an example in which the connector 41, by which the welder is connectable to a robot at interface 35 (see FIG. 2) is side-mounted relative to the principal axis 42 of torch 42a. Determination of the location and / or orientation of connector 41 relative to principal axis 42a may be made based upon the geometry of the robot 30 to which the welder 40 is to be connected and / or the geometry of the component to be welded. Welder 40 may be used as follows: - First, a weld path is defined along a surface of a component to be welded. The weld path definition may be defined by rotation of a series of axes of a robot and rotation of the wire feed guide of the welder. The rotations of robot axes and wire feed guide may be defined to be performed simultaneously such that the torch of the welder traverses along the defined weld path, following the wire feed guide. Once defined, the component may be welded by moving the active welding torch along the defined path and feeding welding wire through the wire feed guide into the path of the active welding torch (for example, into an electrical arc in the case of a TIG welder). The wire feed guide is rotatable about a principal axis of the torch of the welder and is rotatably independent of movement of the welding torch along the welding path by the robot, so that it may lead the welding torch along the weld path. It will be understood that the invention is not limited to the embodiments abovedescribed and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and subcombinations of one or more features described herein.

Claims

1. A welder (40) for a robot (30), the welder (40) comprising:a connector (41) for connecting the welder (40) to the robot (30);a welding torch (42) connected to the connector (41), the welding torch (42) having a principal; axis (42a);a motor (56); anda wire feed guide (55) configured to guide a welding wire (54) to extend towards the principal axis of the welding torch (42);wherein the wire feed guide (54) is rotatable by the motor (56) about the principal axis (42a) of the welding torch (42).

2. The welder of claim 1, wherein the welding torch is selected from one of a tungsten inert gas welding torch, a laser welding torch, an oxy-acetylene welding torch.

3. The welder of claim 2 or 3, wherein the principal axis of the welding torch is offset from a rotational axis of the robot to which the welder is connected.

4. The welder of claim 3, wherein the principal axis of the welding torch is inclined relative to the rotational axis of the robot to which the welder is connected.

5. The welder of claim 3 or 4, wherein the rotational axis of the robot is a rotational axis of a wrist of the robot.

6. The welder of any preceding claim, wherein the wire-feeding guide is connected to the motor via a gear-train.

7. The welder of any preceding claim, wherein the wire feed guide is rotated in dependence upon a defined weld path.

8. The welder of any preceding claim, wherein the motor is controlled by a motor controller, wherein the motor controller is part of a controller of the robot or interfaces with the controller of the robot.

9. The welder of any preceding claim, wherein the robot is a six-axis robot.

10. A method of welding using a welder of any preceding claim, the method comprising:defining a weld path along a surface of a component to be welded;welding the component by moving welding torch along the defined path, wherein a welding wire feed guide to the welding torch is rotatable about a principal axis of the torch of the welder and is rotatably independent of movement of the welding torch along the welding path by the robot.

11. The method of claim 10, wherein the welding torch is selected from one of a tungsten inert gas welding torch, a laser welding torch, and an oxy-acetylene welding torch.Application No: GB2319877.3Examiner: John HewetClaims searched: 1-11Date of search: 20 June 2024Patents Act 1977: Search Report under Section 17Documents considered to be relevant:Category Relevant to claims Identity of document and passage or figure of particular relevance X 1 to 11 US 2019 / 0070685 Al (MARCHIONE) see esp fig 2 X 1 to 11 CN 112548281 B (FUZHOU) see esp fig 1; and WPI abstract, accession number: 2021-344838 X 1 to 9 CN 100475407 C (FANUC) see esp fig 1; and WPI abstract, accession number: 2006-197406 X 1 to 11 CN 105798873 A (DING SHILIN) see esp figs 7 to 9; and WPI abstract, accession number: 2016-47492H X 1 to 11 CN 111037050 A (BEIHANG) see esp fig 1; and WPI abstract, accession number: 2020-34692GCategories:X Document indicating lack of novelty or inventive step A Document indicating technological background and / or state of the art. Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of same category. before the filing date of this invention. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:Search of GB, EP. WO &US patent documents classified in the following areas of the UKCX :International Classification:Subclass Subgroup Valid From B23K 0009 / 12 01 / 01 / 2006 B23K 0026 / 14 01 / 01 / 2014 B23K 0026 / 146 01 / 01 / 2014

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