GB2478275A

GB2478275A - Induction heating apparatus and method

Info

Publication number: GB2478275A
Application number: GB1003082A
Authority: GB
Inventors: Per Thomas Moe; Bjorn Halmrast; Kjell Rabben; Bjarne Salberg; Jan Inge Audestad; James Burnell-Gray; Wayne Rudd; Denis Bradbury
Original assignee: Tubefuse Applications BV
Current assignee: Tubefuse Applications BV
Priority date: 2010-02-24
Filing date: 2010-02-24
Publication date: 2011-09-07
Also published as: GB201003082D0

Abstract

A planar induction member 8 having an aperture 10 formed therein, is configured to receive a current for inductively heating an object such as a pipe 4,6 for example, during and/or after welding of the object to a further object. The induction member 8 is configured to permit current flow around the aperture 10, a slot 15,17 acting as a current barrier. A further slot, diametrically to the slot 15.17, extending from the aperture towards the circumference of the induction member may be provided (fig 10). Insulation material may be inserted in the slots. An actuate or straight ferritic member 27,28 may be positioned on the induction member to guide the magnetic field. Coolant is circulated via passages 32,36. The induction heater 2 is configured to control heat supplied to the object. and a sensor such as a temperature sensor 50 is provided, the sensor having at least a partially unobstructed field of view of a heated portion of the object and/or having an at least partially unobstructed access to a heated portion of the object. Controlled relative movement between the work-piece and the heater may be provided. Conductors 25,26 may cross to avoid interference.

Description

HEATING APPARATUS AND METHO

FIELD OF THE INVENTION

The present invention relates to an apparatus and method for inductively heating an object and, particularly though not exclusively, for heating an object such as a pipe during a welding process.

BACKGROUND OF THE INVENTION

Induction heating is a well known non-contact technique for heating a conductive article which relies upon the generation of eddy currents in the article using high frequency magnetic fields. Induction heating is capable of being used to raise the temperature of a metal article above a melting temperature of the article within seconds.

Induction heating has been used for a range of purposes such as heat treatment, pipe bending, welding, brazing, sealing and cooking. For example, production of seam welded tubes by induction welding is a mature manufacturing process of significant commercial importance. Welding of pipes, rods and tubes has also been performed quite extensively using induction heating. However, there are still significant technical challenges related to the use of induction heating for the formation by welding of butt joints, lap joints and the like. This is especially the case

for the welding of oilfield tubulars.

Resistive heating may provide an alternative to induction heating for welding.

Although resistive heating has limitations with respect to the uniformity of the temperature field and the design of the heating equipment, it has been shown that resistive heating of conductive articles by the direct application of a high frequency current to the articles in preparation for or during welding is significantly more efficient than conventional induction heating techniques. This is because conventional induction coils induce eddy currents not only in regions of the articles to be welded together, but also over a significant distance extending away from the regions of the articles resulting in a temperature field which is significantly more elongated than for direct high frequency resistive heating. Such an elongated field is generally incompatible with metal deformation resulting in an unfavourable final shape for the weld and unhavourable welding pressures. In addition, the energy consumption is high and cooling times are long. Hence, conventional induction welding can be regarded as inefficient.

When using conventional coils for inductively heating articles prior to welding, there are also significant limitations relating to temperature measurement and process control. In order to secure completely satisfactory process control the temperature in the regions of the articles to be welded together should be continuously measured. This may be achieved by non-contact optical pyrometers or IR cameras. However, such non-contact temperature sensors may require an unobstructed view of the weld region, which may be difficult to obtain when using conventional induction coils, since such coils require much space. As a consequence, induction welding is usually performed without using any feedback systems, and the weld quality may be compromised. Conventional coils also render heat treatment directly after welding difficult since the size of these coils makes it difficult to position the coils properly after welding.

An additional difficulty when using conventional coils is the measurement of weld shape during and directly after welding when the coil is in position. With conventional coils, the view of the weld is often obstructed and the measurement of weld shape is incomplete.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided an induction heater comprising: an induction member having an aperture formed therein, wherein the induction member is configured to receive a current for inductively heating an object.

Such an induction member is inexpensive to manufacture and can be made with improved accuracy relative to conventional induction coils which are generally shaped by bending. Such an induction member is particularly, though not exclusively, suitable for use with a small scale welding apparatus such as that disclosed in co-pending UK patent application no. GB1000415.8 which is incorporated herein by reference in its entirety.

The induction member may be planar.

The induction member may be non-planar. For example, the induction member may comprise a curved portion.

The induction member may comprise a plate, panel, sheet or the like.

The induction member may have a thickness and a lateral extent in a direction perpendicular to the thickness, wherein the thickness is less than the lateral extent. For example, the induction member may have a thickness, a length and a width, wherein the thickness is less than the length and the width.

The induction member may be formed from a sheet of material by any combination of casting, powder metallurgy, punching, rolling, cutting, bending, drilling, machining, milling, or the like.

The induction member may have a uniform cross-section. For example, the induction member may have a uniform cross-section in a plane perpendicular to a thickness of the induction member.

The induction member may comprise an outer periphery that has a round, oval, square, or rectangular shape or any other regular shape. The induction member may have an outer periphery that has an irregular shape.

The aperture may be sized and/or shaped to permit the object to extend therethrough. For example, the aperture may be sized and/or shaped to permit the object to extend therethrough with a clearance between a periphery of the aperture and the object.

The aperture may be configured to permit a desired separation between the induction member and an end of the object.

The induction heater may be configured to provide a desired field of view of the object and/or to provide a desired degree of access to the object before, during and/or after heating. For example, the induction member may be configured to provide a desired field of view of the object and/or to provide a desired degree of access to the object before, during and/or after heating. This arrangement may be beneficial when using temperature sensors and/or sensors for measuring a size, shape, surface profile and/or surface roughness and the like of the object. In particu'ar, this arrangement may be beneficial when using non-contact sensors such as remote temperature sensors and remote sensors for measuring a size, shape, surface profile and/or surface roughness and the like of the object. For example, the thickness of the induction member and/or the size and/or shape of the aperture may be chosen to provide a desired field of view of the object or to provide a desired degree of access to the object.

The aperture may be configured to permit an object to extend therethrough before, during and/or after heating of the object. This arrangement may be advantageous when heating an object at one or more positions along a length of the object. An aperture arrangement may also be advantageous when heating an end portion of an object in preparation for butt welding to an end portion of a further object.

The aperture may be configured to permit both the end portion of the object and the end portion of the further object to extend therethrough.

The aperture may be configured to prevent an object from extending therethrough before, during and/or after heating of the object. Such an aperture may be advantageous when heating an extremity of object such as an end portion of an object.

The aperture may be adjustable. For example, the aperture may have an adjustable size and/or shape.

The induction heater may be configured to cause a current flow within the induction member.

The induction member may be configured to receive an alternating current.

For example, the induction member may be configured to receive a high frequency alternating current.

The induction member may be configured to produce a desired magnetic field and thereby generate a desired spatial temperature distribution in an object being heated. For example, the thickness of the induction member may be chosen to induce a desired spatial temperature distribution in the object.

The induction heater may be configured to permit current flow around the aperture. For example, the induction member may be configured to permit current flow around the aperture.

The induction member may comprise a current barrier that is configured to restrict current flow across the current barrier. For example, the current barrier may be configured to restrict alternating current flow across the current barrier. The current barrier may be configured to restrict high frequency alternating current flow across the current barrier.

The current barrier may be at least partially formed in the induction member.

For example, the current barrier may comprise at least one feature formed in the member, such as a gap, split, slit, slot, channel, groove or the like formed in the induction member. __,

The current barrier may comprise a material which is less conductive to current than a material of the induction member. For example, the induction member may be formed from a material which is generally conductive to current, whilst the current barrier may comprise an insulating material.

The current barrier may extend from the aperture towards an edge of the induction member.The current barrier may extend from the aperture to the edge of the induction member.

The current barrier may extend in a straight line.

The current barrier may extend from the aperture in a first direction towards a first edge of the induction member. The current barrier may extend from the aperture in a second direction opposite the first direction towards a second edge of the induction member opposite the first edge.

The induction member may comprise a pair of contacts for receiving current.

The contacts may be configured to receive alternating current. For example, the contacts may be configured to receive high frequency alternating current.

The contacts may be positioned either side of the current barrier. The contacts may be positioned adjacent to the current barrier. Such an arrangement of the contacts relative to the current barrier may promote current flow between the contacts through the induction member around the aperture in preference to current flow between the contacts through the induction member across the current barrier.

In particular, such an arrangement may promote current flow through the induction member around a significant portion of a periphery of the aperture.

The induction heater may be configured to receive electrical current from an electrical supply. The electrical supply may be external to the induction heater.

The induction heater may comprise an electrical supply. The electrical supply may comprise an alternating current supply such as a high frequency alternating current supply. The electrical supply may comprise a power supply, a current source or a voltage source.

The induction member may be connected to the electrical supply by a pair of conductors. A respective conductor may extend from a respective contact of the induction member to a respective terminal of the electrical supply.

The induction heater may comprise the pair of conductors.

The conductors may be crossed. Crossing the conductors in this way may result in a reduction in inductance associated with the conductors.

The induction heater may comprise a ferritic element for guiding a magnetic

field.

The ferritic element may serve to concentrate the magnetic field extending through the aperture.

The ferritic element may be integral with the induction member.

The ferritic element may be attached to the induction member.

The ferritic element may be detachably attachable to the induction member.

The ferritic element may be partially or completely separable from the induction member.

The ferritic element may be located at or adjacent to a periphery of the aperture.

The ferritic element may be located between a periphery of the aperture and an edge of the induction member.

The ferritic element may extend around at least a portion of a periphery of the aperture.

The ferritic element may be located on or adjacent to one side of the induction member.

The ferritic element may be located at, adjacent to, or over the current barrier.

For example, the ferritic element may span or bridge the current barrier. Such an arrangement of the ferritic element may serve to concentrate the magnetic field extending through the aperture adjacent to the current barrier to at least partially compensate for a localised reduction in the magnetic field in the vicinity of the current barrier arising as a consequence of reduced current flow across the current barrier.

The ferritic element may, therefore, serve to improve the uniformity of the magnetic field and thereby improve the uniformity of heating provided by the induction heater.

The induction heater may comprise one or more further ferritic elements for

guiding a magnetic field.

The ferritic element and the one or more further ferritic elements may be located on or adjacent to the same side of the induction member.

The ferritic element and the one or more further ferritic elements may be located on or adjacent to opposite sides of the induction member.

The ferritic element may be movable.

The ferritic element may be movable with the induction member.

The ferritic element may be movable relative to the induction member. For example, the induction heater may comprise a ferritic element actuator for moving the ferritic element relative to the induction member. The ferritic element actuatOr may be configured to move the ferritic element before, during and/or after heating of an object using the induction heater.

Such movement of the ferritic element relative to the induction member may confer several advantages when heating an object. Firstly, the ferritic element may be moved to adjust or tune the magnetic field distribution and, therefore, the distribution of heat provided to the object from the induction heater. Secondly, the ferritic element may be moved to provide a desired a field of view of the object or to provide a desired degree of access to the object before, during andlor after heating.

The ferritic element actuator may comprise a manually activated actuator, an electrically activated actuator, a pneumatically activated actuator, a hydraulically activated actuator, a chemically activated actuator or the like or any suitable combination thereof.

The ferritic element actuator may comprise a movable base configured to hold the ferritic element, wherein the base has an internal thread that is arranged to co-operate with an external thread of a rotatable shaft. The shaft may be configured for manually rotation, for example, with the aid of a handle, or the shaft may be configured for rotation by a motor such as an electric motor or an internal combustion engine or the like.

The ferritic element actuator may comprise a movable base configured to hold the ferritic element, wherein the base is movable using a solenoid or a pneumatic or hydraulic cylinder or the like.

The ferritic element actuator may be configured to move the ferritic element away from or towards the induction member. The ferritic element actuator may be configured to move the ferritic element whilst maintaining a separation between the ferritic element and the induction member. For example, the ferritic element actuator may be configured to move the ferritic element around or adjacent to a periphery of the aperture or the ferritic element actuator may be configured to move the ferritic element away from or towards the periphery of the aperture.

The induction heater may comprise a cooling arrangement configured to remove heat from the induction member. For example, the cooling arrangement may be configured to remove heat generated by current flow in the induction member.

The cooling arrangement may be attached to the induction member.

The cooling arrangement may be integral with the induction member.

The cooling arrangement may be formed internally within the induction member.

The cooling arrangement may comprise at least one of a cooling device, a heat exchanger, or a heat sink or the like.

The cooling arrangement may comprise a lamellar structure.

The cooling arrangement may comprise a coolant fluid conduit.

The cooling arrangement may comprise a plurality of coolant fluid conduits.

The induction member may define the or each coolant fluid conduit.

The induction member may comprise the or each coolant fluid conduit.

The induction member may comprise a tubular portion configured for connection to a coolant fluid pipe.

The induction member may comprise a tubular portion configured for receiving a coolant fluid pipe. The induction member may comprise a tubular portion configured to hold the coolant fluid pipe.

The or each coolant fluid conduit may be formed internally within the induction member.

The or each coolant fluid conduit may comprise flow control features such as fins, ribs, turbulators or the like in any combination thereof. For example, the flow control features may be configured to instigate or cause turbulence of the coolant fluid in the or each coolant fluid conduit. Such flow control features may serve to enhance a cooling efficiency of the cooling arrangement.

The induction member may define a coolant fluid conduit, a coolant fluid inlet and a coolant fluid outlet, wherein the coolant fluid conduit extends from the coolant fluid inlet to the coolant fluid outlet. The coolant fluid inlet and the coolant fluid outlet may be located at the same or different edges of the induction member. The coolant fluid inlet and the coolant fluid outlet may be located at the same or different sides of the induction member.

The coolant fluid inlet may be configured for connection to a coolant fluid pipe.

The coolant fluid outlet may be configured for connection to a coolant fluid pipe.

The cooling arrangement may be configured to provide a desired field of view of the object or to provide a desired degree of access to the object before, during and/or after heating.

The induction heater may comprise a plurality of cooling arrangements, each cooling arrangement being configured to remove heat from the induction member.

The induction member may be movable relative to an object being heated.

The induction member may be movable independently of the ferritic element.

The induction member and the ferritic element may be movable together.

The induction member, the ferritic element and the cooling arrangement may together constitute a heating assembly. The heating assembly may be movable relative to an object being heated.

The induction heater may comprise an induction member actuator for moving the induction member relative to an object being heated. The induction member actuator may be configured to move the induction member before, during and/or after heating of the object.

Such movement of the induction member relative to the object may confer several advantages when heating the object. For example, the induction member may be moved to adjust or tune the magnetic field distribution and, therefore, the distribution of heat provided to the object from the induction member. The induction member may be moved to provide a desired field of view of the object and/or to provide a desired degree of access to the object before, during and/or after heating.

The induction member actuator may comprise a manually activated actuator, an electrically activated actuator, a pneumatically activated actuator, a hydraulically activated actuator, a chemically activated actuator or the like or any suitable combination thereof.

The induction member actuator may comprise a movable base configured to hold the induction member, wherein the base has an internal thread that is arranged to co-operate with an external thread of a rotatable shaft. The shaft may be configured for manual rotation, for example, with the aid of a handle, or the shaft may be configured for rotation by a motor such as an electric motor or an internal combustion engine or the like.

The induction member actuator may comprise a movable base configured to hold the induction member, wherein the base is movable using a solenoid or a pneumatic or hydraulic cylinder or the like.

The induction member actuator may be configured to move the induction member away from or towards the object. For example, where the object extends through the aperture, the heating assembly actuator may be configured to move the induction member such that a periphery of the aperture is moved relative to the object without engaging the object.

The induction member actuator may be configured to move the induction member whilst maintaining a separation between the object and the induction member. For example, where the object extends through the aperture, the induction member actuator may be configured to move the induction member relative to the object without engaging the object.

Where the object is elongated along an axis and extends through the aperture, the induction member actuator may be configured to move the induction member axially and/or radially relative to the object.

The induction member actuator may be configured to move the heating assembly.

The induction member may comprise two or more parts. The two or more parts may be configurable to form the aperture. For example, the two or more parts may be detachably attachable to one another to form the aperture. The two or more parts may be partially or completely separable. The ferritic element may comprise two or more parts, each ferritic element part being associated with a corresponding induction member part. For example, each ferritic element part may be mounted on or adjacent to a corresponding induction member part. Each ferritic element part may be movable relative to a corresponding induction member part.

The induction heater may comprise a plurality of induction members. One or more of the plurality of induction members may be configured as defined above.

At least two induction members may be electrically isolated from one another.

For example, at least two induction members may be separated by an electrically insulating member so as to form a laminar structure.

At least two induction members may be electrically connected to one another.

At least two induction members may be movable together whilst maintaining a fixed spatial relationship between the at least two induction members.

The induction heater may comprise an induction member actuator which is configured to move at least two induction members together whilst maintaining a fixed spatial relationship between the at least two induction members.

At least two induction members may be movable independently relative to one another.

The induction heater may comprise a plurality of induction member actuators, wherein each induction member actuator is independently controllable to move a corresponding induction member relative to another induction member.

The induction heater may comprise a sensor configured to sense a property of the object being heated.

The induction heater may comprise a remote sensor.

The induction heater may comprise a tactile sensor.

The induction heater may comprise an optical sensor.

The induction heater may comprise a capacitive sensor.

The induction heater may be configured so as to provide the sensor with at least a partially unobstructed field of view of and/or at least partially unobstructed access to a heated portion of the object.

The induction heater may be configured so as to provide the sensor with at least a partially unobstructed field of view of and/or at least partially unobstructed access to a heated portion of the object before, during and/or after heating of the heated portion.

The induction heater may be configured so as to provide the sensor with at least a partially unobstructed field of view of and/or at least partially unobstructed access to a portion of the object adjacent to the induction member, for example, within the aperture.

The induction heater may be configured so as to provide the sensor with at least a partially unobstructed field of view of and/or at least partially unobstructed access to a portion of the object that is subjected to a magnetic field when current flows in the induction member.

The induction member and/or the aperture may be configured so as to provide the sensor with at least a partially unobstructed field of view of and/or at least partially unobstructed access to a heated portion of the object. For example, a thickness of the induction member and a size and/or shape of the aperture may be chosen relative to a size and/or shape of the object so as to provide the sensor with at least a partially unobstructed field of view of and/or at least partially unobstructed access to a heated portion of the object.

The induction heater may, for example, comprise a temperature sensor such as a thermometer, thermocouple, thermistor, resistance temperature detector (RTD), infrared camera or a pyrometer or the like or any combination thereof.

The controller may be configured to control the induction heater according to a plurality of temperatures of the object or a temperature distribution associated with the object as sensed by the temperature sensor.

The induction heater may, for example, comprise a sensor for sensing a spatial property of the object such as a shape, size, surface profile and/or surface roughness or the like or any combination thereof. For example, the induction heater may comprise an optical sensor, an ultrasonic sensor or the like.

The induction heater may, for example, comprise a position sensor for sensing a position of the object. For example, the induction heater may comprise a position sensor for sensing a position of the object relative to the induction member and/or for sensing a position of a first object relative to a second object. For example, the induction heater may comprise an optical vision system, a capacitance measurement sensor or the like.

The induction heater may comprise a controller configured to receive a signal from the sensor and to control a current flowing in the induction member according to the received signal. For example, the controller may be configured to control an electrical supply connected to the induction member to control the current flowing in the induction member according to the received signal.

The controller may be configured to control an alternating current supplied to the induction member.

The controller may be configured to control a magnitude of the alternating current or a root mean square value of the alternating current.

The controller may be configured to control power, voltage or current supplied to the induction member.

The controller may be configured to control a frequency of the alternating current.

The controller may be configured to control a position of the induction member relative to the object being heated.

The controller may be configured to control a position of a ferritic element relative to the induction member.

The induction heater may be configured for heat treating an object, For example, the induction heater may be configured to raise a temperature of at least a portion of an object to a predetermined temperature for a predetermined period of time.

The induction heater may be configured to raise a temperature of at least a portion of an object sequentially to a plurality of predetermined temperatures and to hold the temperature at each predetermined temperature for a corresponding predetermined period of time.

The induction heater may be configured to heat a first object before, during and/or after w&ding to a second object. For example, the induction heater may be configured to heat a first object before, during and/or after welding to a second object by any combination of forge welding, flash welding, frictional welding and the like.

The induction heater may be configured to heat a first object before, during and/or after shaping of the first object in preparation for welding to a second object.

The induction heater may, for example, be configured to heat a first object having a bevelled portion before, during and/or after formation of the bevelled portion. The induction heater may, for example, be configured to heat a first object having a machined, smoothed or polished portion before, during and/or after formation of the machined, smoothed or polished portion. The induction heater may be configured to heat a first object having a surface treated portion before, during and/or after surface treatment of the surface treated portion.

The induction heater may be configured to heat an object for the formation by welding of a butt joint or a lap joint or the like. For example, the induction heater may be configured to heat an end of a first object for butt welding the end of the first object to an end of a second object.

In at least one embodiment, the induction heater may be configured to heat an end of a first pipe for butt welding to an end of a second pipe.

The induction heater may be configured to heat two or more objects simultaneously. For example, the induction heater may be configured to heat two or more objects before, during and/or after welding the two or more objects together.

The induction heater may be configured to heat two or more objects of the same, similar or dissimilar materials. For example, the induction heater may be configured to heat two or more objects of the same, similar or dissimilar metals. The metals may, for example, comprise low or medium alloy steels, duplex steels, clad steels, coated steels, aluminium alloys, copper alloys or the like.

The induction heater may be configured to heat pipes including pipes comprising low and medium alloy steels, duplex steels, clad steels, coated steels, aluminium alloys, copper alloys or the like.

According to a second aspect of the present invention there is provided a welding apparatus comprising: an induction heater comprising an induction member having an aperture formed therein, wherein the induction member is configured to receive a current for inductively heating an object.

It should be understood that the optional features disclosed in relation to the induction heater of the first aspect may also apply either alone or in any combination in relation to the welding apparatus of the second aspect.

The welding apparatus may be configured for welding first and second objects together. For example, the welding apparatus may be configured to heat the first object andfor the second object before, during and/or after welding of the first and second objects.

The welding apparatus may be configured to weld two or more objects together, wherein each of the two or more objects comprises the same, similar or dissimilar materials. For example, the welding apparatus may be configured to weld two or more objects together, wherein each of the two or more objects comprises the same, similar or dissimilar metals. The metals may, for example, comprise low or medium alloy steels, duplex steels, clad steels, coated steels, aluminium alloys, copper alloys or the like.

The welding apparatus may be configured for any combination of forge welding, flash welding, frictional welding and the like of the first and second objects together.

The welding apparatus may be configured to weld a shaped portion of a first object to a second object. The welding apparatus may, for example, be configured to weld a bevelled portion of the first object to the second object. The welding apparatus may be configured to weld a bevelled portion of the first object to a bevelled portion of the second object.

The welding apparatus may be configured to weld a machined, smoothed or polished portion of a first object to a second object. The welding apparatus may, for example, be configured to weld a machined, smoothed or polished portion of the first object to a machined, smoothed or polished portion of the second object.

The welding apparatus may be configured to weld a surface treated portion of a first object to a second object. The welding apparatus may, for example, be configured to weld a surface treated portion of the first object to a surface treated portion of the second object.

The welding apparatus may be configured for the formation by welding of a butt joint or a lap joint or the like.

The welding apparatus may be configured for the welding of pipes including pipes comprising low and medium alloy steels, duplex steels, clad steels, coated steels, aluminium alloys, copper alloys or the like.

The welding apparatus may be configured for discrete, batch and/or continuous welding.

The induction member may be movable relative to the first and/or second objects before, during and/or after welding of the first and second objects.

The welding apparatus may be configured for butt welding an end of a first object to an end of a second object. In at least one embodiment, the welding apparatus may be configured for butt welding first and second pipes together.

The welding apparatus may be configured to heat an end portion of the first object and/or an end portion of the second object before, during and/or after welding together of the ends of the first and second objects.

The welding apparatus may be configured for heat treating the first object and/or the second object before, during and/or after welding of the first and second objects. For example, the welding apparatus may be configured to raise a temperature of at least a portion of the first object and/or the second object to a predetermined temperature for a predetermined period of time.

The welding apparatus may be configured to raise a temperature of at least a portion of the first object and/or the second object sequentially to a plurality of predetermined temperatures and to hold the temperature at each predetermined temperature for a corresponding predetermined period of time.

The induction member may be positioned adjacent to the end of the first object and/or to the end of the second object.

The induction member may be movable. The induction member may be movable relative to the end of the first object and/or to the end of the second object before, during and/or after welding of the first and second objects. For example, the welding apparatus may comprise an induction member actuator for moving the induction member relative to the end of the first object and/or to the end of the second object before, during and/or after welding of the first and second objects.

The induction member actuator may be used to move the induction member relative to the end of the first object and/or to the end of the second object to adjust a temperature of the end portion of the first object and/or a temperature of the end portion of the second object. For example, the induction member actuator may be used to move the induction member relative to the end of the first object and/or to the end of the second object to balance a temperature difference between the end portions of the first and second objects.

The induction member actuator may be used to move the induction member so as to maintain a relative position of the induction member with respect to the end of the first object during movement of the first object and/or to maintain a relative position of the induction member with respect to the end of the second object during movement of the second object.

The induction member may be configured to provide a predetermined heating effect of the end portion of the first object and the end portion of the second object for a predetermined separation between the ends of the first and second objects.

The induction heater may comprise a ferritic element.

The ferritic element may be movable. The ferritic element may be movable during andlor after welding of the first and second objects.

The ferritic element may be movable with the induction member.

The ferritic element may be movable relative to the induction member. For example, the induction heater may comprise a ferritic element actuator for moving the ferritic element relative to the induction member before, during and/or after welding of the first and second objects.

The ferritic element actuator may be used to move the ferritic element relative to the induction member to adjust a temperature of the end portion of the first object and/or a temperature of the end portion of the second object. For example, the ferritic element actuator may be used to move the ferritic element relative to the induction member to balance a temperature difference between the end portions of the first and second objects.

The ferritic element may be configured to provide a predetermined heating effect of the end portion of the first object and the end portion of the second object for a predetermined separation between the ends of the first and second objects.

The aperture may be configured to permit the first and/or second object to extend therethrough before, during and/or after heating of the object.

The aperture may be configured to prevent the first and/or second object from extending therethrough before, during and/or after heating of the object. The use of an induction member having such an aperture for welding requires the induction member to be positioned adjacent to the end of the first object and/or adjacent to the end of the second object to permit heating thereof and the induction member to subsequently be removed from between the ends of the first and second objects to permit the ends of the first and second objects to engage one another.

The induction member may comprise two or more parts. The two or more parts may be configurable to form the aperture. For example, the two or more parts may be detachably attachable to one another to form the aperture. The two or more parts may be partially or completely separable. Such an arrangement of the induction member allows the induction member to be removed from between the ends of the first and second objects. Such an arrangement may, in particular, permit the ends of the first and second objects to engage one another when the aperture is configured to prevent the first and/or second object from extending therethrough.

The welding apparatus may comprise one or more further induction heaters, each further induction heater having an induction member for carrying current, which induction member has an aperture formed therein and is configured to receive a current.

According to a third aspect of the present invention there is provided a method of inductively heating an object comprising: positioning an induction member having an aperture formed therein adjacent to the object; and supplying a current to the induction member.

The method may comprise sensing a property of the object.

The method may comprise sensing a property of a heated portion of the object.

The method may comprise remotely sensing a property of the heated portion of the object.

The method may comprise sensing a property of the heated portion of the object before, during and/or after heating of the heated portion.

The method may comprise sensing a property of a portion of the object adjacent to the induction member.

The method may comprise sensing a property of a portion of the object subjected to a magnetic field when current flows in the induction member.

The method may comprise sensing a temperature of the object. The method may comprise sensing a spatial property of the object such as a shape, size, surface profile and/or surface roughness or the like. The method may comprise sensing a position of the object.

The method may comprise adjusting the current in response to the sensed property.

The method may comprise supplying an alternating current to the induction member.

The method may comprise adjusting a magnitude or a root mean square value of the alternating current.

The method may comprise adjusting a frequency of the alternating current.

The method may comprise adjusting a position of the induction member relative to the object in response to the sensed property.

The induction heater may comprise a ferritic element and the method may comprise adjusting a position of the ferritic element relative to the object in response to the sensed property.

According to a fourth aspect of the present invention there is provided a method of inductively heating an object comprising: positioning an induction member adjacent to the object; supplying a current to the induction member; sensing a property of a heated portion of the object; and adjusting the current in response to the sensed property.

The steps of the method may be performed in any order. The steps may be performed sequentially. Two or more of the steps may overlap. Two or more of the steps may be performed simultaneously.

The induction member may have an aperture formed therein.

The method may comprise adjusting a frequency of the alternating current.

According to a fifth aspect of the present invention there is provided a method of inductively heating an object comprising: positioning an induction member adjacent to the object; supplying a current to the induction member; sensing a property of a heated portion of the object; and adjusting a position of the induction member relative to the object in response to the sensed property.

The induction member may have an aperture formed therein.

The method may comprise sensing a property of the heated portion of the object before, during and/or afler heating of the heated portion.

According to a sixth aspect of the present invention there is provided a method of inductively heating an object comprising: positioning an induction member and an associated ferritic element adjacent to the object; supplying a current to the induction member; sensing a property of a heated portion of the object; and adjusting a position of the ferritic element relative to the object in response to the sensed property.

The induction member may have an aperture formed therein.

According to a seventh aspect of the present invention there is provided a method of welding a first object to a second object comprising: positioning an induction member having an aperture formed therein adjacent to the first and/or second objects; supplying a current to the induction member; and bringing the first and second objects into contact.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further described by way of non-limiting example only with reference to the following figures of which: Figure 1(a) is a schematic plan view of an induction heater constituting a first embodiment of the present invention in use heating first and second pipes; Figure 1(b) is a cross-section on AA of the induction heater of Figure 1(a); Figure 1(c) is a cross-section on BB of the induction heater of Figure 1(a); Figure 2(a) is a cross-section on AA of the induction heater of Figure 1(a) in which an induction member of the induction heater located between ends of the first and second pipes prior to butt welding of the ends of the first and second pipes; Figure 2(b) is a cross-section on AA of the induction heater of Figure 1(a) in which an induction member of the induction heater is located adjacent a clamping arrangement for holding the second pipe prior to butt welding the ends of the first and second pipes; Figure 2(c) is a cross-section on M of the induction heater of Figure 1(a) during or after butt welding the ends of the first and second pipes by moving the end of the first pipe into engagement with the end of the second pipe without movement of the induction member; Figure 2(d) is a cross-section on AA of the induction heater of Figure 1(a) during or after butt welding the ends of the first and second pipes by moving the end of the first pipe into engagement with the end of the second pipe and moving the induction member so as to remain centrally aligned with respect to the ends of the first and second pipes; Figure 3 is a schematic plan view of an induction heater constituting a second embodiment of the present invention in position around a respective pipe or pipes; Figure 4 is a schematic plan view of an induction heater constituting a third embodiment of the present invention in position around a respective pipe or pipes; Figure 5(a) is a schematic plan view of an induction heater constituting a fourth embodiment of the present invention in ue heating first and second pipes; Figure 5(b) is a cross-section on AA of the induction heater of Figure 5(a); Figure 5(c) is a cross-section on BB of the induction heater of Figure 5(b); Figure 6 is a schematic plan view of an induction heater constituting a fifth embodiment of the present invention in an open configuration relative to a pipe or pipes; Figure 7 is a schematic plan view of an induction heater constituting a sixth embodiment of the present invention in an open configuration relative to first and second pipes; Figure 8(a) is a schematic plan view of an induction heater constituting a seventh embodiment of the present invention in a closed configuration relative to first and second pipes; Figure 8(b) is a cross-section on AA of the induction heater of Figure 8(a); Figure 8(c) is a schematic plan view of the induction heater of Figure 8(a) in an open configuration relative to first and second pipes; Figure 8(d) is a cross-section on AA of the induction heater of Figure 8(c); Figure 9(a) is a schematic cross-section of an induction heater constituting an eighth embodiment of the present invention prior to butt welding first and second pipes; Figure 9(b) shows induction heater of Figure 9(a) after butt welding the first and second pipes; and Figure 10 is a schematic plan view of an induction heater constituting a ninth embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Figures 1(a) to 1(c) show an induction heater generally designated 2 in use heating a first upper pipe 4 co-axially aligned with a second lower pipe 6 respectively.

Although the induction heater 2 is shown heating first and second pipes 4, 6 in Figures 1(a) to 1(c), it should be understood that the induction heater 2 may be configured to heat objects other than pipes. Furthermore, the induction heater 2 may be configured to heat only one object at a time or to heat more than two objects simultaneously.

The induction heater 2 comprises a steel plate induction member 8 having a circular aperture 10 formed therein. The aperture 10 has a circumference 12 that is configured so as to provide clearance between an external diameter 14 of the first and second pipes 4,6.

The induction member 8 is split so as to form a gap 15 along a line extending from the circumference 12 of the aperture 10 to an edge 16 of the induction member 8. An insulating material such as a dielectric insulating material is inserted in the gap so as to form a current barrier 17 which at least partially suppresses currently flow through the induction member 8 across the current barrier 17.

The induction member 8 comprises contacts 18 and 19 for receiving a high frequency alternating current 20, which contacts 18 and 19 are disposed along the edge 16 of the induction member 8 either side of the current barrier 17. This arrangement of the contacts 18, 19 ensures that, in use, at least a majority of the current 20 flows between the contacts 18, 19 through the induction member 8 around the aperture 10 thus generating an alternating magnetic field 21 that extends through the aperture 10.

The induction heater 2 further comprises an electrical supply 22 having first and second terminals 23 and 24 for supplying the high frequency alternating current to the induction member 8 and first and second conductors 25 and 26. The first conductor 25 extends between the first terminal 23 and the first contact 18. Similarly, the second conductor 26 extends between the second terminal 24 and the first contact 19. The first and second conductors 25 and 26 are crossed to reduce an associated inductance. The electrical supply 22 is configured to supply powers of up to several hundred kilowatts, for example up to 500 kW or up to 300 kW, electric currents of up to several thousand amperes, for example up to 5000 A or up to 4000 A, and voltages of up to several tens of volts, for example up to 100 V or up to 70 V. The induction heater 2 comprises a first ferritic element 27 located above the induction member 8 and a second ferritic element 28 located below the induction member 8, which ferritic elements 27, 28 serve, in use, to guide or concentrate a magnetic field 21 as indicated in Figures 1(b) and 1(c). The first and second ferritic elements 27, 28 extend around a portion of the circumference 12 of the aperture 10 across the current barrier 17 thereby pulling or distorting the magnetic field 21 towards the current barrier 17 so as to at least partially compensate for a reduction in magnetic field strength extending through the aperture 10 in a region adjacent to the current barrier 17 caused by suppression of current flow across the current barrier 17. Put another way, the first and second ferritic elements 27, 28 serve to improve the uniformity of the magnetic field and the resulting heating effect produced by the induction heater 2 during operation.

The induction heater 2 comprises a cooling arrangement generally designated 30, which cooling arrangement 30 comprises a first steel tube 32 attached to a side edge 34 of the induction member 8 and a second steel tube 36 attached to an opposite side edge 38 of the induction member 8. The cooling arrangement 30 further comprises an inlet coolant fluid pipe 40 connected to a first end of the first tubes 32, an outlet coolant fluid pipe 41 connected to a first end of the second tubes 36 and a U-shaped coolant fluid pipe 42 connected between second ends of the first and second tubes 32, 36. The coolant fluid pipes 40, 41 and 42 and the first and second tubes 32, 36 together define a coolant fluid conduit for a flow of coolant water 43. The induction member 8 and the first and second tubes 32, 36 form a thermally conductive path so that, in use, heat which is resistively generated in the induction member 8 is conducted away from the induction member 8 and removed by the coolant water 43.

For a given current 20 and a given gap 44 between pipe ends 46 and 48 of the first and second pipes 4 and 6 respectively, the induction member 8 is configured so as to produce desired axial temperature fields in the pipes 4 and 6 adjacent to the pipe ends 46 and 48 respectively. For example, for an alternating current 20 of approximately 4000 A root mean square and a gap 44 of approximately 2 mm, a 20 mm thick steel induction member 8 having a circular aperture 10 of diameter 216 mm (8)) is capable of inductively heating the ends 46 and 48 of steel pipes 4 and 6 having an outer diameter 14 of approximately 219 mm (8) to a temperature of approximately 1000 °C while the corresponding temperatures of the pipes 4 and 6 at axial locations 20 mm away from the respective pipe ends 46 and 48 are approximately 500 °C. One skilled in the art will, however, understand that such values are only indicative and the exact value of current supplied will depend on the material and geometry of the induction member, the material and geometry of the pipes, and the relative configuration of the induction member and the pipes.

The induction heater 2 also comprises a pyrometer 50 directed towards the end 46 of the first pipe 4. The induction member 8 is configured so as to provide the pyrometer 50 with a clear field of view of a circumference of the end 46 of the first pipe 4 when the pipe end 46 is above the induction member 8 as shown in Figure 1 or the pipe end 46 extends into the aperture 10 of the induction member 8. In particular, the thickness of the induction member 8 and the diameter of the aperture relative to the outer diameter 14 of the first pipe 4, are chosen so as to provide the pyrometer 50 with a clear field of view of a circumference of the pipe end 46.

The induction heater 2 further comprises a controller 51. As indicated by the dotted lines in Figure 1(a), the controller 51 is configured for communication with the pyrometer 50 and the electrical supply 22. In use, the pyrometer 50 senses a temperature, the controller 51 receives a temperature signal representative of the sensed temperature from the pyrometer 50 and the controller 51 controls a magnitude or root mean square value and/or a frequency of the current 20 supplied by the electrical supply 22 according to the received temperature signal. It should be understood that the electrical supply 22 and the controller 51 have been omitted from Figures 1(b) and 1(c) for clarity. One skilled in the art will, however, understand that rather than or in addition to the controller 51 controlling the magnitude or root mean square value and/or a frequency of the current 20, the controller 51 may control the voltage and/or electrical power supplied by the electrical supply 22.

The induction heater 2 further comprises a heating assembly actuator (not shown) for moving a heating assembly 52 comprising the induction member 8, the ferritic elements 27,28 and the coolant arrangement 30 relative to the pipes 4,6. The heating assembly actuator may be realised using a variety of technologies known to one skilled in the art. For example, the heating assembly actuator may be driven electrically, hydraulically or pneumatically. The heating assembly actuator is configured to move the heating assembly 52 radially and/or axially relative to the pipes 4,6. As indicated by the dotted line 53 in Figure 1, the controller 51 is configured for communication with the heating assembly actuator. In use, the controller 51 controls the heating assembly actuator so as to control the radial and/or axial positions of the heating assembly 52 relative to the pipes 4,6 according to the received temperature signal from the pyrometer 50.

The induction heater 2 further comprises first and second ferritic element actuators (not shown) for moving the ferritic elements 27 and 28 respectively relative to the induction member 8 and/or relative to the pipes 4,6. The ferritic element actuators may be realised using a variety of technologies known to one skilled in the art. For example, the ferritic element actuators may be driven electrically, hydraulically or pneumatically. As indicated by the dotted line 54 in Figure 1, the controller 51 is configured for communication with the ferritic element actuators. In use, the controller 51 controls the ferritic element actuators so as to control the radial and/or axial positions of the ferritic elements 27, 28 relative to the pipes 4,6 according to the received temperature signal from the pyrometer 50.

Figures 2(a) to 2 (d) illustrate the position of the heating assembly 52 of Figure 1 at different times in use during a process for butt welding the first and second pipes 4 and 6 together in which the first and second pipes are held by respective clamping arrangements 55 and 56.

In Figure 2(a) the heating assembly 52 is shown in position prior to welding such that the induction member 8 is located between the pipe ends 46 and 48 and the pipes 4 and 6 are co-axial with the circular aperture 10 of the induction member 8.

In Figure 2(b) the heating assembly 52 is shown in position prior to welding such that the induction member 8 is located adjacent the clamping arrangement 56 and the second pipe 6 extends through the aperture 10.

Figure 2(c) shows a position of the heating assembly 52 during or after welding of the pipe end 46 of the upper pipe 4 to the pipe end 48 of the lower pipe 6 after the upper pipe 4 is moved towards the lower pipe 6 without movement of the heating assembly 52. During or after welding, the pipes 4, 6 may become deformed along axial portions adjacent to a weld interface 60 between pipe ends 46 and 48 such that the outer diameter of the pipes 4, 6 adjacent to the weld interface 60 may be enlarged relative to the outer diameter 14 of the pipes at an axial position distant from the weld interface 60. Accordingly, the aperture 10 is configured to provide clearance for the enlarged pipe portions thereby enabling the weld interface 60 to be located within or be axially translated through the aperture 10 without interference either during or after welding.

Figure 2(d) shows a position of the heating assembly 52 during or after welding of the pipe end 46 of the upper pipe 4 to the pipe end 48 of the lower pipe 6 after the upper pipe 4 and/or the lower pipe 6 are moved towards one another and the position of the heating assembly 52 is moved so as to maintain a height of a middle of the heating assembly 52 aligned with a height of a middle of the gap 44 between the first and second pipe ends 46, 48.

Figure 3 shows a second embodiment of an induction heater generally designated 102. The induction heater 102 has features which correspond to like features of the induction heater 2 of Figure 1 and which are identified by reference numerals which are equal to the reference numerals used for the like features in Figure 1 incremented by 100. The induction heater 102 comprises ferritic elements 127, 128 which extend circumferentially around an aperture 110 formed in an induction member 108 across a current barrier 117. The ferritic elements 127, 128 are located at a radial position between a circumference 112 of the aperture 110 and an edge 118 of the induction member 108.

Figure 4 shows a third embodiment of an induction heater generally designated 202. The induction heater 202 has features which correspond to like features of the induction heater 2 of Figure 1 and which are identified by reference numerals which are equal to the reference numerals used for the like features in Figure 1 incremented by 200. The induction heater 202 comprises ferritic elements 227, 228 that extend in a straight line across and perpendicular to a current barrier 217. One skilled in the art will appreciate that further alternative embodiments having different configurations of ferritic elements may also be possible.

Figure 5 shows a fourth embodiment of an induction heater generally designated 302. The induction heater 302 has features which correspond to like features of the induction heater 2 of Figure 1 and which are identified by reference numerals which are equal to the reference numerals used for the like features in Figure 1 incremented by 300. The induction heater 302 of Figure 5 differs from the induction heater 2 of Figure 1 in that the induction heater 302 has a cooling arrangement 330 comprising a coolant fluid conduit 360 formed internally within an induction member 308. The coolant fluid conduit 360 extends from a coolant fluid inlet 362 formed at an edge 318 of the induction member 308, round an aperture 310 formed in the induction member 308, to a coolant fluid outlet 364 formed at the edge 318 of the induction member 308. The coolant fluid conduit 360 comprises an inlet tapering portion 366 that expands into the induction member 308 away from the coolant fluid inlet 362 and an outlet tapering portion 368 that narrows towards the coolant fluid outlet 364. In addition, the coolant fluid conduit 360 splits into two secondary coolant fluid conduits 370 which each extend from the inlet tapering portion 366 to the outlet tapering portion 368. The coolant fluid inlet 362 is configured for connection to a coolant fluid inlet pipe 372 and the coolant fluid outlet 364 is configured for connection to a coolant fluid outlet pipe 374. Such an internal cooling arrangement 330 may provide more efficient cooling when the induction heater 302 is in use compared with the external cooling arrangement 30 of the induction heater 2 of Figure 1.

Figure 6 shows a fifth embodiment of an induction heater generally designated 402. The induction heater 402 has features which correspond to like features of the induction heater 2 of Figure 1 and which are identified by reference numerals which are equal to the reference numerals used for the like features in Figure 1 incremented by 400. The induction heater 402 differs from the induction heater 2 of Figure 1 in that the induction heater 402 comprises a steel induction member 408 having first and second separable parts 480 and 482. The first and second parts 480 and 482 are detachably attachable to one another. The first and second parts 480 and 482 of the induction member 408 are configured to engage one another along a linear interface that extends from an edge 416 of the induction member 408 across the induction member 408 along a current barrier 417. The first part 480 of the induction member 408 has an associated conductor 425 attached for supplying current thereto and associated upper and lower ferritic element parts 484 and 485. The second part 482 of the induction member 408 has an associated conductor 426 attached for supplying current thereto and associated upper and lower ferritic element parts 486 and 487.

The induction heater 402 comprises a cooling arrangement generally designated 430, which cooling arrangement 430 comprises a first steel tube 432 attached to a side edge 434 of the induction member 408 and a second steel tube 436 attached to an opposite side edge 428 of the induction member 408. The cooling arrangement 430 further comprises a flexible U-shaped coolant fluid pipe 442 connected between the first and second tubes 432, 436.

The induction heater 402 is configurable by adjusting a bend angle of the flexible U-shaped coolant fluid pipe 442 between an open configuration shown in Figure 5 in which the first and second parts 480 and 482 of the induction member 408 are separated by pivoting with respect to the U-shaped coolant fluid pipe 442, to a closed configuration (not shown) in which the first and second parts 480 and 482 of the induction member 408 engage one another along the interface so as to form a circular aperture 410 therebetweefl. The open configuration allows first and/or second pipes 404 and/or 406 to be moved into position before heating or provides access to first and/or second pipes 404 and/or 406 after heating. The closed configuration is the operating configuration used for heating.

Similarly, Figure 7 shows a sixth embodiment of an induction heater generally designated 502. The induction heater 502 has features which correspond to like features of the induction heater 402 of Figure 6 and which are identified by reference numerals which are equal to the reference numerals used for the like features in Figure 5 incremented by 100. The induction heater 502 differs from the induction heater 402 of Figure 6 in that the induction heater 502 is configurable by translating first and second parts 580 and 582 of an induction member 508 without pivoting with respect to a flexible U-shaped coolant fluid pipe 542 between an open configuration in which the first and second parts 580 and 582 are separated, to a closed configuration (not shown) in which the first and second parts 580 and 562 of the induction member 508 engage one another so as to form a circular aperture 510 therebetWeefl.

Figures 8(a) and 8(b) show a seventh embodiment of an induction heater generally designated 602. The induction heater 602 has features which correspond to like features of the induction heater 502 of Figure 7 and which are identified by reference numerals which are equal to the reference numerals used for the like features in Figure 7 incremented by 100. The induction heater 602 differs from the induction heater 502 of Figure 7 in that the induction heater 602 comprises an induction member 608 having a circular aperture 610 formed therein, wherein the circular aperture 610 has a diameter which is smaller than an outer diameter 614 of first and second pipes 604, 606 to be heated by the induction heater 602.

Accordingly, when the induction heater 602 is in use for heating pipe ends 646 and 648 of the first and second pipes 604 and 606 respectively, the induction heater 602 is arranged in the closed configuration shown in Figure 8(a) in which an induction member 608 of the induction heater 602 is positioned between and adjacent to the pipe ends 646 and 648. The open configuration, shown in Figure 8(b), allows first and/or second pipes 604 and/or 606 to be moved into position before heating or provides access to first and/or second pipes 604 and/or 606 after heating. The open configuration also allows pipe ends 646 and 648 to be forged together after heating.

Figure 9 shows an eighth embodiment of an induction heater generally designated 702 before and after forge welding of pipes 704 and 706. The induction heater 702 has features which correspond to like features of the induction heater 2 of Figure 1 and which are identified by reference numerals which are equal to the reference numerals used for the like features in Figure 1 incremented by 700. The induction heater 702 of Figure 9 differs from the induction heater 702 of Figure 1 in that the induction heater 702 has no ferritic elements. The induction heater 702 comprises a heating assembly 752 comprising an induction member 708 and a coolant arrangement 730. As shown in Figure 9(a), the induction member 708 is located between end faces 746 and 748 of the first and second pipes 704 and 706 respectively prior to forging. The induction heater 702 is operated so as to heat pipe ends 746 and 748 and the upper pipe 704 is moved relative to the lower pipe 706 so as to forge pipe ends 746 and 748 together during and/or after heating of the pipe ends 746 and 748 resulting in the configuration shown in Figure 9(b). The pipes 704, 706 may become deformed during welding along axial portions adjacent to a weld interface 760 between pipe ends 746 and 748 such that the outer diameter of the pipes 704, 706 adjacent to the weld interface 760 may be enlarged relative to the outer diameter 714 of the pipes at axial positions distant from the weld interface 760.

Accordingly, the aperture 710 is configured to provide clearance for the enlarged pipe portions thereby enabling the weld interface 760 to be located within or be axially translated through the aperture 710 without interference either during or after welding.

Figure 10 shows a ninth embodiment of an induction heater generally designated 802. The induction heater 802 has features which correspond to like features of the induction heater 2 of Figure 1 and which are identified by reference numerals which are equal to the reference numerals used for the like features in Figure 1 incremented by 800. Like the induction heater 2 of Figure 1, the induction heater 802 of Figure 10 has an induction member 808 comprising a gap 815 extending radially away from a circular aperture 810 so as to form a current barrier 817. However, in contrast to the induction member 8 of Figure 1, the induction member 808 of Figure 10 comprises a portion generally designated 890 that projects outwardly from an edge 816 of the induction member 808. Furthermore, the gap 815 extends along the outwardly projecting portion 890 of the induction member 808 so as to form a pair of electrical contacts 818, 819 for the supply of current to the induction member 808. In addition, the gap 815 extends radially away from the aperture 810 in opposite directions from two diametrically opposed positions 892 and 894 on the circumference of the aperture 810. As shown in Figure 10, however, the gap 815 only extends radially away from position 894 part-way towards an edge 896 of the induction member 808 opposite the edge 816. The extension of gap 815 in opposite directions from the aperture 810 has the effect of improving the symmetry of the electromagnetic field and hence improving the uniformity of heating provided by the induction member 808 when using the induction member 808 without ferritic elements.

It should be understood that the embodiments described herein are merely exemplary and that modifications may be made thereto without departing from the scope of the present invention. For example, although the induction member 8 is described as being formed of steel in the foregoing embodiments, the induction member 8 may comprise or be formed from any electrically and thermally conductive material. The induction member 8 may, for example, comprise a metal other than steel, such as aluminium, copper or the like. Similarly, although the tubes 32 and 36 of the coolant arrangement 30 are described as being formed of steel in the foregoing embodiments, the tubes 32 and 36 may comprise or be formed from any thermally conductive material. For example, the tubes 32 and 36 may comprise a metal other than steel, such as aluminium, copper or the like.

Although the aperture 10 has been described in all of the foregoing embodiments as being circular, the aperture 10 may be non-circular. The aperture may be configured for heating an object having a specific geometry. The aperture may, for example, have a shape and/or size so as to provide clearance for an object to extend or pass therethrough, before, during and/or after heating. The aperture 10 may, for example, have a shape and/or size so as to produce a desired temperature field in an object formed from a specific material and/or having a specific geometry.

The induction heater 2 may comprise one or more further coolant arrangements. For example, the induction heater 2 may comprise a plurality of coolant fluid conduits or secondary coolant fluid conduits. The or each coolant fluid conduit may comprise flow control features such as fins, ribs, turbulators or the like in any combination thereof. For example, the flow control features may be configured to instigate or cause turbulence of the coolant fluid in the or each coolant fluid conduit.

In addition or as an alternative to the pyrometer 50, the induction heater 2 may comprise an infrared camera or the like or a tactile temperature sensor such as a thermometer, thermocouple, thermistor, resistance temperature detector (RTD) or the like or any combination thereof.

The induction heater 2 may comprise a remote or tactile sensor for measuring a size, shape, surface profile andfor surface roughness or the like of the object being heated.

Claims

CLAIMS1. An induction heater comprising an induction member having an aperture formed therein, wherein the induction member is configured to receive a current for inductively heating an object.
2. An induction heater as claimed in claim 1, wherein the induction member is planar.
3. An induction heater as claimed in claim 1 or 2, further configured to cause a current flow within the induction member.
4. An induction heater as claimed in any preceding claim, wherein the induction member is configured to permit current flow around the aperture.
5. An induction heater as claimed in claim 4 wherein, the induction member comprises a current barrier that is configured to restrict current flow across the current barrier.
6. An induction heater as claimed in claim 5, wherein the current barrier comprises at least one of a gap, split, slit, slot, channel, groove or the like formed in the induction member.
7. An induction heater as claimed in claim 5 or 6, wherein the current barrier comprises a material which is less conductive to current than a material of the induction member.
8. An induction heater as claimed in any of claims 5 to 7, wherein the current barrier extends from the aperture towards an edge of the induction member.
9. An induction heater as claimed in any of claims 5 to 8, wherein the current barrier extends in a straight line.
10. An induction heater as claimed in claim 9, wherein the current barrier extends from the aperture in a first direction towards a first edge of the induction member and the current barrier extends from the aperture in a second direction opposite the first direction towards a second edge of the induction member opposite the first edge.
11. An induction heater as claimed in any of claims 5 to 10, wherein the induction member comprises a pair of contacts for receiving current wherein the contacts are positioned either side of the current barrier.
12. The induction heater as claimed in any preceding claim wherein the induction member is movable relative to an object being heated.
13. An induction heater as claimed in any preceding claim comprising a ferriticelement for guiding a magnetic field.
14. An induction heater as claimed in any of claims 5 to 13 comprising a ferritic element for guiding a magnetic field wherein the ferritic element is located at, adjacent to, or over the current barrier.
15. An induction heater as claimed in claim 13 or 14 wherein the ferritic element is movable with or relative to the induction member.
16. The induction heater as claimed in any preceding claim comprising a cooling arrangement configured to remove heat from the induction member. ii.
17. The induction heater as claimed in claim 16 wherein the cooling arrangement is formed internally within the induction member.
18. The induction heater as claimed in claim 16 or 17 wherein the cooling arrangement comprises a coolant fluid conduit.
19. The induction heater as claimed in any preceding claim comprising two or more parts which are configurable to form the aperture.
20. The induction heater as claimed in any preceding claim comprising a plurality of induction members.
21. The induction heater as claimed in any preceding claim comprising a sensor configured to sense a property of the object being heated.
22. The induction heater of claim 21 wherein the induction heater comprises a temperature sensor.
23. The induction heater of claim 21 or 22 wherein the induction heater comprises a sensor for sensing a spatial property of the object.
24. The induction heater of any of claims 21 to 23 wherein the induction heater comprises a sensor for sensing a position of the object.
25. The induction heater as claimed in any of claims 21 to 24 configured so as to provide the sensor with at least a partially unobstructed field of view of and/or at least partially unobstructed access to a heated portion of the object.
26. The induction heater as claimed in any of claims 21 to 25 comprising a controller configured to receive a signal from the sensor.
27. The induction heater as claimed in claim 26 wherein the controller is configured to control a current flowing in the induction member according to the received signal.
28. The induction heater as claimed in claim 26 or 27 wherein the controller is configured to control a position of the induction member relative to the object being heated according to the received signal.
29. The induction heater as claimed in any of claims 26 to 28 comprising a ferritic element, wherein the controller is configured to control a position of the ferritic element relative to the induction member according to the received signal.
30. The induction heater as claimed in any preceding claim configured to raise a temperature of at least a portion of an object to a predetermined temperature for a predetermined period of time.
31. A welding apparatus comprising an induction heater as claimed in any preceding claim.
32. A welding apparatus as claimed in claim 31 wherein the induction heater is configured to heat a first object and/or a second object before, during and/or after welding of the first and second objects.Cfl4 44fl? 4 L II.
33. A welding apparatus as claimed in claim 32 wherein the induction heater is configured to permit the induction member to be positioned adjacent to the end of the first object and/or to the end of the second object.
34. A welding apparatus as claimed in claim 32 or 33 wherein the induction heater is configured so as to maintain a relative position of the induction member with respect to the end of the first object during movement of the first object and/or to maintain a relative position of the induction member with respect to the end of the second object during movement of the second object.
35. A welding apparatus as claimed in any of claims 31 to 34 wherein the aperture is configured to permit the first and/or second object to extend therethrough before, during and/or after heating of the first and/or second object.
36. A method of inductively heating an object comprising: positioning an induction member having an aperture formed therein adjacent to the object; and supplying a current to the induction member.
37. A method of inductively heating an object as claimed in claim 36 comprising sensing a temperature, a spatial property or a position of the object.
38. A method of inductively heating an object as claimed in claim 37 comprising adjusting the current in response to the sensed temperature, spatial property or position of the object.
39. A method of inductively heating an object as claimed in claim 37 or 38 wherein the induction heater comprises a ferritic element and the method comprises adjusting a position of the ferritic element relative to the object in response to the sensed temperature spatial property or position of the object.
40. A method of welding a first object to a second object comprising: positioning an induction member having an aperture formed therein adjacent to the first and/or second objects; supplying a current to the induction member; and bringing the first and second objects into contact.
41. A method of inductively heating an object comprising: positioning an induction member adjacent to the object; supplying a current to the induction member; sensing a property of a heated portion of the object; and adjusting the current in response to the sensed property.
42. A method of inductively heating an object comprising: positioning an induction member adjacent to the object; supplying a current to the induction member; sensing a property of a heated portion of the object; and adjusting a position of the induction member relative to the object in response to the sensed property.
43. A method of inductively heating an object comprising: positioning an induction member and an associated ferritic element adjacent to the object; supplying a current to the induction member; sensing a property of a heated portion of the object; and fl1 I 1 ?7-1 -bulk imoort 4 6 adjustin9 a position of the ferritic element relative to the object in response to the sensed.5Ml!4?7lJIt Sand