Improvements to welding apparatus and a braking system therefore

Abstract

A device may create welded joints in pipelines, using a track attached to a pipe. Support wheels 12 may be fixed in position; whereas support wheels 14 / 24 may move in two directions (which can clamp t

Description

The invention to which this applicantin relates is welding apparatus and particularly, although not necessarily exclusively, apparatus which can be used to form a welded joint between first and second components which are provided at an offset angle and which have a contoured interface and which requires the join to be formed along a path which varies, typically in the x,y and z axes. An example of a join with which the apparatus is particularly effective is that which is known as a “saddle” join which is so called as the shape of the welded join between two cylindrical objects is similar to the shape of a horse saddle when positioned on a horse. A further aim of the invention is to provide a braking system which can used as part of the welding apparatus, or with other forms of moving apparatus which are required to be controlled and prevented from experiencing uncontrolled acceleration. Furthermore the welding apparatus to which the invention is particularly useful is that which is provided to be operable within and movable along a confined space and without requiring direct manual control so that the performance of the welding can be performed automatically or semi automatically by the apparatus and without the need for a person to be present at the specific location in which the weld join is formed. One such environment in which the apparatus is particular useful is the internal space of a pipeline and to which another pipeline or pipeline component is to be joined to create a sealed join and so as to prevent fluid passing along the interior space from leaking through the join. However, it should be appreciated that the formation of the welded join using the apparatus as herein described, can be utilised in many forms of confined spaces such as ship building, oil rig manufacturing, and in general, m the formation of a welded join where space is relatively confined and / or the weld join is at least partially formed within an interior space of one or more of the components. Conventional apparatus is typically provided with propulsion means to allow the same to be moved along, for example, the interior of the pipeline, to the location at which the welded join is to be formed and this form of apparatus are typically referred to as “bugs” and while the use of this apparatus is known and is of particular advantage for use in forming weld joins in difficult to access areas and / or in environments which are potentially hazardous, conventionally, the use of the apparatus is restricted to the circumferential welding of joins in pipes or to tanks with flat or regular shaped profiles so that the conventional apparatus is typically only operable successfully when operating on a join which varies in two dimensions and it is not possible to form a welded join with a compound curved shape using the conventional apparatus. The principal reason as to why the bug apparatus cannot be used to form this form of weld is that the apparatus typically includes a band or track on which the body of the apparatus is mounted and moved and the said band or track has to follow the curvature of the primary one of the components which are being joined by the welded join. A further problem with the conventional apparatus is ensuring the safe operation of the apparatus and, in particular, the ability to control the apparatus movement in such a manner as to ensure that damage to the components and / or injury to personnel, is avoided. Conventionally, the apparatus is provided with a track and a movement means such as an electric motor which provides a movement force to be transmitted to move the body of the apparatus along the track, typically via a funicular or a compression drive. When a funicular drive is provided, it is found that the main areas of failure are that of the drive shaft or of the mechanical assembly between a toothed drive wheel and drive shaft. When a compression drive is used, the main cause of failure is found to be the drive shaft and / or compression wheel as the wheels are typically formed of a very hard material but are also relatively brittle and prone to microfractures being created during use which, as a result, means that the compression wheels are expensive and require to be changed frequently and, if not serviced correctly, then the rate of failure increases exponentially with the elapsed time since the last service. In both forms, the mechanical drive, if it fails, means that the apparatus body will descend along the track in an uncontrolled manner until a maximum free travel speed is reached and, if a person is m the path of the apparatus body and is impacted by the body, then significant injury? can be caused. Furthermore, the speed at which the apparatus body moves can mean that when the body reaches the end of the track or a bend or curve on the track, the body can become disengaged from the track and is then liable to collide with other items and / or walls which define the environment in which the apparatus is being used and which, due to the weight and speed of movement of the body can mean that there is a significant impact force and typically damage is caused at least to the apparatus body and / or surrounding environment. A first aim of the invention is to provide welding apparatus in a form which allows the same to be used to form welded joins along a path with a relatively complex shape, such as, for example, a welded saddle join between two components which are angularly offset. A further aim is to provide a braking system for apparatus in a form which is safer to use by preventing uncontrolled movement which may be caused, for example, by a failure or malfunction of the apparatus and in particular, to provide a means to prevent the uncontrolled movement of the apparatus body if failure should occur. In a first aspect of the invention, there is provided apparatus for use in creating a welded join, said apparatus including a track along which a weld body is provided to be driven, a plurality of support members depending outwardly from the said body, said support members provided to contact with and mechanically locate the weld body during the formation of the said welded join via a welding head which is moved along with the body to follow a path along which the welded join is formed and wherein at least one of said support members is provided to be fixed in position with respect to the weld body and at least one of the support members is selectively movable in at least two directions with respect to the said weld body during operation of the apparatus to form the welded join. Typically, the apparatus has a front end at, or adjacent to, which the said welding head is located and a first set of said support members are located at or adjacent to the front end of the weld body. Typically, the first set of support members are fixed in position with respect to the weld body during use of the apparatus. Typically, a second set of support members are positioned at a spaced distance from the first set of support members and typically spaced towards the opposing, rear end of the weld body and the second set of support members are provided to be movable in a first direction substantially in line with the direction of movement of the weld body when in use and a second direction which, typically, is perpendicular to the first direction. In one embodiment, the movement of the body is achieved via at least one drive member contacting the track and / or a wall of the component with which the apparatus is being used. Typically, the said at least one drive member applying the motive force for the weld body, is movable at least in a direction perpendicular to the direction of movement of the weld body. In one embodiment, a motive force is generated by a motor included as part of the apparatus and the motive force is transferred to the at least one drive member via a gear reduction system to allow free movement whilst having a constant force applied to the support members motion and which, typically, is unchanged regardless of the speed of movement of the apparatus at that time. Typically, the motive force which is applied at the commencement of movement and subsequent movement of the weld body is substantially constant in order to provide the ability to form a substantially uniform welded join. In one embodiment the welded join which is formed is of a relatively complex shape such as a saddle weld or a compound curved profile weld. Typically the welded join is formed between two components and, in one embodiment, the track is positioned in engagement with at least one of the said components on which the welded join is to be formed and positioned intermediate the surface of the said component and the weld body of the apparatus. In one embodiment the track is formed so as to substantially follow the contour of the surface of said component on which it is positioned and is substantially uniformly spaced from said surface. In one embodiment the track is provided in the form of a band and includes a series of mechanical features such as apertures, protrusions and / or other formations, to allow the motive force to be applied from the at least one drive member such as to move the weld body along the track as the welded join is formed. In one embodiment, the mechanical features are provided at spaced intervals along the said track. Typically, the at least one drive member includes a toothed wheel and the teeth of the said wheel sequentially contact and locate with said series of mechanical features located along the length of the track. Typically the apparatus includes a braking system which is operable to prevent and / or reduce an increase in speed as a result of otherwise uncontrolled movement of the weld body which may be caused by a failure of, for example, the at least one drive member, track and / or motor. In one embodiment the braking system includes a housing in which a variable resistance material, such as a nomNewtonian fluid, is contained and sealed along with a first disc or wheel and a second disc or wheel. Typically, the said first and / or second discs have at least one surface with agitation means formed thereon such as a series of protrusions and / or indents thereon and / or apertures formed therethrough. Typically said first and second discs are located within the nomNewtoman fluid. Typically the second disc is connected to the gear box and hence motor of the apparatus, via a shaft and is rotated so as to reflect the speed of the motor shaft rotation and change along with changes in that speed of rotation and the first disc is connected so as to act as an indication of the speed of movement of the weld body with respect to the track and / or component to which the same is mounted. Typically during normal operation, when the motive force is applied in a controlled manner between the motor and track via the drive member, the difference in speeds of rotation of the first and second discs is zero or at least lower than a predetermined value and at which there is little or no turbulence imparted to tire variable resistance fluid within the housing by the rotation of the discs and the movement of the agitation means and so the fluid remains m a low viscosity state with no or very little resistance or “braking” created by the fluid on the movement of the first disc and hence movement of the body along the track. However, should there be an occurrence of a significant increase in the difference in the speeds of rotation of the respective discs, such as may be caused, for example, by the motive force applied from the motor, via the at least one drive member, to the track being lost and which would result in the apparatus body entering a free fall state, the agitation means such as in the form of the surface protrusions, indents and / or apertures are moved more rapidly by the rapid rotation of at least one of the discs and so act to more greatly agitate the variable resistance fluid. This causes the viscosity of the fluid to increase, typically in direct proportion to the increase in the difference in speed of rotation between the two discs. This, increased viscosity fluid in turn, acts as a brake to the speed of rotation of the first disc and as the same is connected to the drive means for imparting the motive force to the track, causes the speed of movement of the weld body along the track to be controlled and reduced and / or stopped by the resistance to the speed of rotation of the first disc by the increase in viscosity of the Nom Newtonian fluid. Typically a predetermined value at which the increase in viscosity has a significant braking effect by effectively moving the braking assembly into a braking mode can be selected by for example selecting the particular fluid which is used and / or the type and number of agitation means provided and / or the volume of the housing and thereby the difference value of the respective rotational speeds at which the braking mode acts. In a further aspect of the invention, there is provided guided driven apparatus, said apparatus including a body for movement along a surface via a motive force created by movement means and said apparatus includes a braking system to allow the automatic application of a braking force to resist or reduce the speed of movement of the said apparatus with respect to said surface when a change in operating condition occurs, wherein said braking system includes a first rotatable disc with a speed of rotation related to the speed of movement of the apparatus along the said surface at that instant of time, a second rotatable disc connected to a motive force for the movement of the body along said surface and the speed of rotation of the second disc related to the level of said motive force at that instant of time, said first and second discs located within a variable resistance material and sealed in a housing, and wherein when a difference in said speeds of rotation of the first and second discs is less than a predetermined value, the braking system is in a first braking condition and when the difference in said speeds of rotation of the said first and second discs increases, agitation of the said variable resistance material by the increased speed of rotation of one or both discs increases and causes an increase in the resistance of the variable resistance material to provide the braking system in a second, braking, condition to reduce the speed of rotation of at least one of said discs and exert a braking force on the movement of the body along the said surface. In one embodiment the said variable resistance material is a non-Newtonian fluid, and the viscosity of the fluid is increased by the increase in agitation of the same. Typically the braking system is in a first condition when the movement of the body with respect to the surface is in a driven controlled manner and when there is a failure in the controlled driven movement of the apparatus the braking system moves to the second condition. In one embodiment it is the speed of rotation of the first disc which becomes significantly greater than the speed of rotation of the second disc. Typically the agitation of the nomNewtonian fluid is increased by the provision of agitation means such as protrusions, indents and / or other features on at least one surface of the said first and / or second discs and / or apertures passing through said first and / or second discs. Typically, the viscosity of the non-Newtonian fluid and the increase in the same, determines the braking force which is applied and, for example, in one embodiment, should the movement means fail and allow uncontrolled movement of the apparatus, the sudden increase in agitation and hence viscosity of the fluid will exert a significant braking force on the movement of the body to reduce the speed of movement and the viscosity of the fluid, may, over time reduce once the movement of the apparatus body comes under control and in turn, the relative viscosity of the nomNewtonian fluid decreases. Specific embodiments of the invention are now described with reference to the following drawings; wherein Figures la-c illustrates apparatus in accordance with one embodiment of the invention. Figures 2a e illustrate the body of the apparatus in greater detail; Figures 3a-f illustrate in a schematic manner embodiments of a braking system in accordance with the invention. Referring firstly to figures la-c, there is illustrated apparatus in accordance with one embodiment of the invention in location with a pipeline 2 for form a welded join between the pipeline and a further component which may be, for example, another pipeline or component for use with the pipeline. The apparatus includes a track 4 which, in this embodiment is in the form of a band located around the exterior surface 6 of the pipeline and the track 4 is uniformly spaced from the surface 6, by a series of engagement and spacing feet 8 which are provided at spaced locations around the track and thereby provide a uniform spacing of the track 4 from the surface 6. Mounted on the track 4, is a weld body 10 of the apparatus and the weld body is located on the track via a series of support members provided as a first set of support members 12 and a second set of support members 14. In this embodiment, in each set, there are provided first and second support members and the support members of the first set 12, are provided in a fixed axial position with respect to the body while the support members in the second set 14 are provided to be movable along at least two axes, with a first axis being in line with the direction of movement of the weld body along the track and the second axis is perpendicular to said first axis. The support members are provided with V-shaped side walls and the first and second sets are spaced apart, in one embodiment adjustably by a user, so as to be spaced apart by a distance so that the opposing edges 21, 22 of the track are located at the base of the respective V in the side walls of the support members 12, 14 and so that the distance between the engagement faces of first and second sets of support members where they engage with the track is substantially equal to the distance between the edges 21, 22 and hence width 16 of the track which means that the track is effectively clamped between the side walls of the support members of the first and second sets 12,14. This ensures that the weld body 10 is retained in position as the same moves along the track in the direction of arrow 18. Typically, the movement of the weld body along the track is driven by means of a drive member 20 which engages with a toothed side wall 22 of the track. This therefore means that rotation of the drive member 20 which also has toothed side walls 23, means that the motive force from a motor in the weld body and which is connected to rotate the drive member 20, moves the drive member along the side wall 22 of the track and hence moves the weld body 10 along the track. Turning now to figures 2a-e, the body 10 of the apparatus is shown in more detail and it is shown that the drive member 20 is provided for driven rotation about axis 25 and is located intermediate the support members of the set 14. Also mounted at the front end 24 of the body is a welding head 26 which is operable to create the welded joint as the apparatus moves along the track. The weld body 10 is also provided with at least one handle 28 so as to allow the safe user movement of the body between different locations of use and the placing of the same in position. The drive member 20 is connected to the motor drive means via a gear assembly 30 which is normally located within a housing and part of the same is removed in the Figures 2a- e for ease of illustration. The weld body also includes a braking system including a sealed housing 32 which is shown in cross section along its longitudinal axis in Figure 3a in a schematic manner and in Figure 3b and which has a sealing cap 33 at one end and a sealed bearing 35 at the other. The housing has a sealed inner cavity 34 which receives therein, a non-Newtonian fluid 36 and in which, there is provided a first disc 38 which is connected via shaft 39 to rotate at the same speed as the drive member 20 and which also includes a bearing seal 41, and a second disc 40 which is connected via shaft 42 to the sealing cap 33 and motor and which rotates the second disc 40 at the same speed as the motive drive force provided by the motor. The first disc assembly is shown in more detail in Figures 3c and d, with the Figure 3c showing the assembly in cross section along the longitudinal axis of the shaft. The second disc assembly is shown in more detail in Figures 3e and f with the assembly shown in cross section along the longitudinal axis of the shaft in Figure 3f. In use, as the weld body is moving along the track, then in normal operating conditions, the first and second discs 38,40 will rotate at substantially the same speed as the motive force from the motor is applied to the drive member and hence movement of the body along the track is achieved at the same or similar speed as the motive force which is applied to the drive member. This therefore means that any difference in speed of rotation of the first and second discs 38,40 will be below a predetermined value and at which it is recognised that the movement of the weld body is controlled and at an expected and safe speed. However, should for example, the motive force applied between the motor and the track fail, so that there is no controlled movement of the body and rather the body movement is under the influence of gravity, the body would normally start to move along the track at an uncontrolled, accelerating and hazardous speed. However, in accordance with the invention, should this occur, the first disc 38 will rotate at the same speed as the drive member 20 which will be accelerating and so the difference between the speed of rotation of the first disc 38 and second disc 40 will increase. As the difference in speed increases, agitation means 44 located on, in the embodiment of Figure 3a the disc 38, and in the embodiment of Figures 3b-f, discs 38 and 40, are increasingly moved through the fluid by the increased speed of rotation of at least one of the discs so causing increased agitation of the nonNewtonian fluid 36 in the housing 32 cavity which, in turn, acts to increase the viscosity of the fluid 36. This increase in viscosity then has the effect of resisting and / or slowing, and hence braking, the speed of rotation of the first disc 38 and the shaft 39 and so slow the speed of rotation of the drive member and hence the body 10 along the track. Thus, the uncontrolled movement of the body along the track is stopped and the body can be brought to a stationary or manageable speed. There is therefore provided apparatus which can be utilised to create relatively complex weld joins in a controlled manner on one or more components and for the same to be controlled remotely such as by wireless or wired communication between a control system at a remote location and the weld body at the weld join location and thereby allow the operator to use the control means to send signals relating to the movement and operation of the apparatus and to receive, via the control system, signals from the weld body indicating the performance, position and movement of the weld body, to and from a remote location at which the control means is provided, and which can be located in a relatively safe and user friendly environment. The provision of the braking system also allows safe operation of the apparatus to be achieved and for uncontrolled movement of the apparatus body, following a controlled movement failure, to be minimised.

Claims

1. Apparatus for use in creating a welded join, said apparatus including a track along which a weld body is provided to be driven, a plurality of support members depending outwardly from the said weld body, said support members provided to contact with and mechanically locate the weld body during the formation of the said welded join via a welding head which is moved along with the body to follow a path along which the welded join is formed and wherein at least one of said support members is provided to be fixed in position with respect to the weld body and at least one of the support members is selectively movable in at least two directions with respect to the said weld body during operation of the apparatus to form the welded join.2.Apparatus according to claim 1 wherein the weld body has a front end at, or adjacent to, which the said welding head is positioned and a first set of said support members are located at or adjacent to the said front end.3.Apparatus according to claim 2 wherein the said first set of said support members are support members which are fixed in position with respect to the weld body.

4. Apparatus according to either claims 2 or 3 wherein a second set of said support members are positioned at a spaced distance from the first set of said support members and towards an opposing rear end of the apparatus.5.Apparatus according to claim 4 wherein said support members of the said second set are provided to be movable in a first direction substantially in line with the direction of movement of the weld body when in use and a second substantially perpendicular direction.

6. Apparatus according to any of the preceding claims wherein the movement of the weld body is achieved via at least one drive member contacting the track.7.Apparatus according to claim 6 wherein the said at least one drive member is rotatable with respect to the track and to engage with the track to move the weld body along the track.

8. Apparatus according to claim 7 wherein the first set of support members are provided to engage with a first edge or side of the track and the at least one drivemember and second set of support members engage with a second side or edge of the track.

9. Apparatus according to claim 8 wherein the said second side or edge of the track opposes the said first edge or side of the track.

10. Apparatus according to any of the preceding claims wherein the track includes a series of mechanical features to allow the drive member to engage with the same and move the weld body along the track as the welded joint is formed.11.Apparatus according to claim 10 wherein the drive member includes a toothed wheel and the teeth of the said wheel sequentially contact and locate with said series of mechanical features located along the length of the track.

12. Apparatus according to any of the preceding claims wherein a motive force applied to move the said weld body is substantially constant during the formation of the welded join.

13. Apparatus according to any of the preceding claims wherein the welded join which is formed is a saddle weld or a compound curved profile weld.

14. Apparatus according to any of the preceding claims wherein the track is positioned in engagement with at least one component on which the welded join is to be formed and is positioned intermediate a surface of the said component and the weld body.

15. Apparatus according to claim 12 wherein the track is formed so as to substantially follow the contour of the surface of said component and be substantially uniformly spaced from said surface.

16. Apparatus according to any of the preceding claims wherein the apparatus includes a braking system operable to prevent and / or minimise the speed of uncontrolled movement of the body with respect to the track.

17. Apparatus according to claim 16 wherein the braking system includes a housing in which a variable resistance material is contained and sealed along with a first disc connected to the drive member and a second disc connected to the motive force.

18. Apparatus according to claim 17 wherein the said first and / or second discs include agitation means formed and / or located thereon.19 Apparatus according to claim 18 wherein the variable resistance material is a nonNewtonian fluid and the viscosity of which is increased by increased agitation by the agitation means.20 Apparatus according to any of claims 16 to 19 wherein an increase tn the difference in speeds of rotation of the first and second discs causes an increase in the agitation, and hence viscosity, of the variable resistance material which acts as a brake to the movement of the weld body along said track.

21. Guided driven apparatus, said apparatus including a body for movement along a surface via a motive force created by movement means and said apparatus includes a braking system to allow the automatic application of a braking force to resist or reduce the speed of movement of the said apparatus with respect to said surface when a change in operating condition occurs, wherein said braking system includes a first rotatable disc with a speed of rotation related to the speed of movement of the apparatus along the said surface at that instant of time, a second rotatable disc connected to a motive force for the movement of the body along said surface and the speed of rotation of the second disc related to the level of said motive force at that instant of time, said first and second discs located within a variable resistance material and sealed in a housing, and wherein when a difference in said speeds of rotation of the first and second discs is less than a predetermined value, the braking system is in a first braking condition and when the difference in said speeds of rotation of the said first and second discs increases, agitation of the said variable resistance material as a result of the increased speed of rotation of one or both discs increases and causes an increase in the resistance of the variable resistance material to provide the braking system in a second, braking, condition to reduce the speed of rotation of at least one of said discs and exert a braking force on the movement of the body along the said surface.

22. Apparatus according to claim 21 wherein the said vanable resistance material is a non-Ncw toman fluid.23.Apparatus according to claims 22 and 23 wherein the viscosity of the variable resistance material increases as a result of the increase in agitation of said material.24 Apparatus according to claims 21-23 wherein when there is a failure in the controlled movement of the body along the surface it is the speed of rotation of the first disc which increases.

25. Apparatus according to any of claims 21-24 wherein the first and / or second discs included agitation means formed or located thereon and / or therethrough.

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