INTERNAL DIAMETER (I.D.) WELDING MACHINE, AND ROTARY DRIVE AND FEED UNIT THEREFOR

Abstract: An internal diameter (I.D.) welding machine (21), and rotary drive and feed unit (24) therefor, is mounted via temporary brackets (19, 20) on an excavator bucket (10), the bores (15, 16) of which are to be repaired (after line boring oversize). The welding bar (22) is rotatably journalled in insulating bushes (28, 29) and has a welding head (30) (of the gas shield MIG type) with a welding tip (34). As the drive and feed unit (24) advances along a shaft (25) mounted on a bracket (27), it causes the welding bar (22) to be rotationally and longitudinally fed through the bores (15, 16) so that the welding tip (34) lays a bead of weld material (64) spirally within the bores (15, 16). The welding machine (21) is removed and the line boring machine is re-installed to enable the bores (15, 16) to be machined to size.

Description: Title: "INTERNAL DIAMETER (I.D.) WELDING MACHINE, AND ROTARY DRIVE AND FEED UNIT THEREFOR" BACKGROUND OF THE INVENTION (1) (Field of the Invention) THIS INVENTION relates to an internal diameter (I.D.) welding machine and to a rotary drive and feed unit therefor. (2) Prior Art Earthmoving, construction and mining equipment such as excavator buckets, loader arms and linkages, machinery articulations and pivot points and the like commonly have bores through mounting lugs or brackets to receive a pivot pin or shaft. The bores become worn due to the high impact loads on the equipment and due to the abrasive nature of the "grinding paste" formed when sand or dirt becomes mixed with the grease. Any wear in the bores is rapidly accelerated to a point where repair or replacement of the damaged component is required. Due to the ever increasing costs of new capital equipment and spare parts, owners are seeking to delay replacement by extending the operating life of existing equipment where such equipment can be economically repaired. It is usual practice to take the following steps to repair the worn bores on equipment such as excavator buckets: (a) a line boring machine is mounted on the bucket via temporary brackets and the bores are machined oversize; (b) the line boring machine is removed, an internal diameter (I.D.) welder is then mounted on the bucket, and the bores are welded to an undersize; and (c) the welding machine is removed, the line boring machine is re-fitted and the bores machined to the correct diameter. This is a slow, laborious task. Each machine must be carefully aligned with the axis of the bores and this is difficult both (1) when the bores have worn eccentrically, and (2) after the welding steps. SUMMARY OF THE PRESENT INVENTION It is an object of the present invention to provide an I.D. welding machine which may be used with portable line boring machines in the field or used in an engineering workshop situation. It is a preferred object to provide a welding machine which can accurately weld the bores of earthmoving, construction or running equipment or the like. It is a further preferred object to provide a welding machine which is relatively inexpensive compared to existing I.D. welding machines. It is a still further preferred object to provide a rotary drive and feed unit for the welding machine. It is a still further preferred object to provide a magnetic (e.g. electromagnetic) mount for the welding machine. Other preferred objects will become apparent from the following description. In one aspect, the present invention resides in an internal diameter (I.D.) welding machine for the repair of bore(s) on equipment including: a tubular welding bar, to extend through the bore(s) to be welded, rotatably journallable in bearings on support brackets on the equipment; means to connect the bar to a rotary drive and feed unit; a welding head mounted in, and extending through, a slot in the bar, or from one end of the bar; and welding gas, wire and/or electricity supply means connected to the welding head and extending through the bar to an end, or the other end thereof. Preferably, the welding bar is of hollow brass tube, with a plurality of elongate slots along its length. Preferably, insulating bushes or support sleeves are provided on the tube to support it in pillar block bearings on the support members. The support members may be mounted on an magnetic head releasably mountable on the equipment to be repaired. Alternatively, the support members may comprise legs and/or brackets bolted, welded (e.g. tack-welded) or otherwise temporarily fixed to the equipment being repaired. Preferably, an insulating block connects the bar to the output shaft of the drive and feed unit. Alternatively, the output shaft is driven by an insulating pulley in the drive feed unit. Preferably, the drive and feed unit has a variable speed and direction of rotation, and a variable feed rate. It is preferred that the rotation speed be set so that the welding tip has a linear speed of approximately 300 mm per minute and that the feed speed is approximately 3-5 mm per revolution. The welding head may be of a MIG-welder of the gasless wire type, flux-cored wire type or gas-shield type. The head may have a plurality of extensions to suit the different internal diameters to be welded. Preferably, the head has a body on which the tip (and any extensions) are angularly adjustable. The welding wire, electrical cable and gas tube preferably enter the bar from either end and are connected to respective source supply units. For the internal welding of joints in pipelines, the support members preferably have adjustable legs to enable the tubular bar to be centred in the pipeline, and the tubular bar is connected to a drive unit which only rotates the tubular bar, without any feed component. In a second aspect, the present invention resides in a rotary drive and feed unit suitable for an I.D. welding machine, a line boring machine or the like including: a screw-threaded shaft mountable on a support; a drive housing; a nut rotatably mountable in or on the drive housing in operable engagement with the shaft; a drive coupling, operably connectable to the machine to be driven, rotatably mounted in or on the drive housing; a motor mounted in or on the housing; and drive means driven by the motor to drive the nut and the drive coupling; so arranged that as the drive coupling rotatably drives the machine, the nut moves the drive housing along the shaft to feed the machine in a linear direction. The shaft may be a ball screw-threaded shaft and the nut complementary thereto. Preferably, the nut is releasably mounted, e.g. by cap screws, on one side of a first drive pulley rotatably joumalled in bushes in the housing. Preferably, the drive coupling is releasably mounted on one side of a second drive pulley rotatably joumalled in bushes in the housing. Preferably, the pulleys are of "TUFNOL", "TEFLON" (trade marks) or nylon material and run in aluminium bushes, the material of the pulleys providing electrical insulation of the nut and drive coupling from the housing. Preferably, the motor is a reversible D.C. motor, preferably of variable speed (or controlled by a variable speed controller). The drive means may comprise a compound gear train reduction unit operably connected to the motor. Preferably, a driven pulley on the motor operably drives the first and second drive pulleys via a timing toothed (or "GILMER") belt. (In a heavy duty unit, the belt and pulleys may be substituted by a chain and sprockets, or by a gear drive train.) BRIEF DESCRIPTION OF THE DRAWINGS To enable the invention to be fully understood, a preferred embodiment will now be described with reference to the accompanying drawings, in which: FIG. 1 is a perspective view of the welding machine assembled to weld the bores of bosses on mounting brackets on an excavator bucket, the welding machine being fitted with the rotary drive and feed unit; FIG. 2 is a sectional side view of the welding head; FIG. 3 is an end view of the drive and feed unit; FIG. 4 is a sectional view taken on line A-A on FIG. 3; and FIG. 5 is a side view of an magnetic support unit for the welding machine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, the excavator bucket 10 has mounting brackets 11, 12 with bosses 13, 14 having aligned bores 15, 16 therethrough. Prior to welding, a portable line boring machine (not shown) is used to machine the bores 15, 16 oversize. The line boring machine has a cutter tool on a boring bar driven by a drive and feed unit (not shown) . The boring bar is rotatably joumalled in pillar block bearings 17, 18 mounted on temporary support brackets 19, 20 tack-welded to the bucket 10. The boring bar is then removed and replaced by the welding machine 21 which is supported by the pillar block bearings 17, 18. The welding machine 21 has a hollow brass welding bar 22 with a plurality of elongate slots in its side wall. A rotary drive and feed unit 24 (to be hereinafter described with reference to FIGS. 3 and 4) is used to rotate and feed the welding bar 22. A ball screw-threaded shaft 25 is mounted on a block 26 on a support bracket 27 welded or bolted to the temporary support bracket 19, the shaft 25 lying parallel to the welding bar 22. The welding bar 22 is supported in insulating sleeves 28, 29 (of "TUFNOL" or "TEFLON" (trade marks) material) in the pillar block bearings 17, 18 for both rotational and longitudinal movement. A welding head 30, to be described in more detail with reference to FIG. 2, is mounted in the welding bar 22 and extends from one slot 23 thereof to enable a bead of weld to be applied to the adjacent bore 15 as the welding head is rotated and advanced through the bore. The welding head 30 (of the gas shield MIG type) is supplied to sources of electricity, welding wire and gas (not shown) by an electric cable 31, welding wire 32 and gas tube 33 which extend through the welding bar 22 from the end. (The welding cable may extend through the welding bar from either end.) The rotary drive and feed unit 24 is provided with suitable gearing so that the rotational speed of the welding head 30 can be set so that the welding tip 34 has a linear speed of approximately 300 mm per minute and a linear feed rate of 3-5 mm per revolution. These speeds may be varied to suit the equipment being welded and the type of welding head being used. Referring now to FIG. 2, the welding head 30 has an aluminium bronze pivot body 35 located in the welding bar 22 by a glass filled "TEFLON" (Registered trade mark) rotary isolating sleeve 36 and is secured by a glass filled "TEFLON" clamp plate 37 and glass filled teflon clamp ring 38, with set screws 39. An aluminium bronze direction block 40 is connected to the pivot body 35 via stainless steel pivot joint 41, with a locking screw 42 accessible via a hole (not shown) in the side wall of welding bar 22. A plurality of brass extensions 43 locate the welding tip 34 at the desired distance from the bore 15. The pivot body 35 is hollow and houses a glass filled "TEFLON" insulating bush 44 which supports one end of the brass pivot tube 45, provided with a thrust bearing 46. An aluminium bronze cable connector 47 has a plurality of bores which receive the ends of respective strands 48 of the electrical welding cable 31, the strands being secured by grub screws 49. The cable connector 47 houses a glass filled "TEFLON" insulating bush 50 and is mounted about the pivot tube 45. A copper impregnated carbon brush 51 ensures effective transfer of the electrical current from the cable connector 47 to the pivot body 35, while the cable connector 47 is isolated from the welding bar 22 by a fixed glass filled "TEFLON" isolating sleeve 52 secured to cable connector 47 by grub screw 53. Pressure is maintained on the faces of brush 51 by spring 54 which is insulated from the cable connector 47 by the head of bush 50 and from strands 48 of electrical welding cable 31 by a glass filled "TEFLON" sleeve 55. The welding wire 32 passes through a wire conduit liner 56 located in the bore of pivot tube 45, and through a wire conduit liner 57; and is secured to the bore 58 of brass gas diffuser block 59 by a grub screw (not shown); and passes through the pivot joint 41 and the bore 60 in the direction block 40 to the tip 34. the gas tube 33 is connected to the pivot tube 45 by adaptor 61 and the welding gas passes therethrough and through ports 62 in pivot tube 45 and through ports 63 in gas diffuser block 59. The gas diffuser block 59 is held in position in the bore of pivot body 35 by a grub screw (not shown). The welding machine 21 is assembled as shown and the welding head 30 is adjusted so that a bead of weld material 64 will be spirally applied to the bore 15. As the welding head is rotated and fed through the bore 15, the welded material lines the bore 15 so that the latter is now undersize. When both bores 15, 16 have been welded, the welding machine is removed and the bores 15, 16 machined to the correct size by the cutter tool of the boring bar of the portable line boring machine which is reinstalled on the bucket. As the pillar block bearings 17, 18 are used during the machining/welding/machining steps, accuracy of the alignment of the bores 15,16 is maintained and setting up and changeover times are markedly reduced. The rotary drive and feed unit will now be described with reference to FIGS. 1, 3 and 4. The rotary drive and feed unit 24 has a housing 65 with a first drive pulley 66 of "TUFNOL" material joumalled in aluminium bushes 67, 68, fixed to the housing. A disengageable ball screw-threaded nut 69, comprising a guide sleeve 70, has a series of holes 71 drilled by increments radially about and longitudinally therealong so as to match the pitch of the ball screw-threaded shaft 25. The holes 71 are machined so that balls 72 are retained in the guide sleeve 70 but may engage shaft 25 when engaging sleeve 73 is slid to the engaged position and is held in place by spring-loaded balls 74 locating in an external groove 75 on the guide sleeve 70. When engaging sleeve 73 is slid to the disengaged position,with spring-loaded balls 74 locating in external groove 76, the balls 72 are now able to "float", allowing the rotary drive and feed unit 24 to be slid along shaft 25. Circlip 77 ensures engaging sleeve 73 is retained on the guide sleeve 70. The guide sleeve 70 is mounted on one side of the first drive pulley 66 by cap screws (not shown). A second drive pulley 78, of "TUFNOL" material, is rotatably joumalled in aluminium bushes 79, 80 fixed to the housing and drive coupling 81 is mounted on one side of the pulley 78 by cap screws 82. The coupling has a pair of spring-loaded balls 83 extending into its bore 84 to releasably engage aligned holes (not shown) in the welding bar 22. A variable speed, reversible, permanent magnet D.C. electric motor 85, driving through a compound gear train reduction, is mounted on the housing 65 and has a driving pulley 86. A toothed timing (or "GILMER") belt 87 passes around the driving pulley 86 and the drive pulleys 66, 78, so that when the motor 85 is operated, the drive coupling 81 rotates the welding bar 22 while the disengageable ball screw nut 69 travels along the shaft 25 to feed the welding bar 22 linearly. A D.C. controller (not shown) is used to control rotation direction and rotation speed of the D.C. electric motor 85. Alternatively, for a fixed speed electric motor, the rate of feed of the driving and feed unit can be varied by using shafts 25 and nuts 69 of different pitch. The length of the feed is only limited by the length of the screw-threaded shaft 25, and of the slotted welding bar 22. Referring now to FIG. 5, the welding machine 21 and the drive feed unit 24 are mounted on a support unit 90, the welding machine 21 having the welding head 30 extending from one end of the welding bar 22. (In an alternative embodiment not shown, and for large diameter bores to be welded, the welding head may extend from one of the slots 23 and be provided with a support brace.) The support unit 90 has an magnetic head 91 releasably mounted on the equipment to be repaired, e.g. an excavator bucket 10 and has a pair of parallel guides 92 on which are adjustably mounted pillar block bearings 93, 94 which rotatably journal the welding bar 22. With this support unit 90, the welding machined can be quickly and easily located and then removed when finished without the need to weld temporary support brackets to the equipment under repair. In addition, the welding machine can be easily used with existing line boring machines. The magnetic head 91 may have a base plate 95 mountable on, and magnetically attached to the bucket 10, fitted with a ball 96 on a post 97. The ball 96 is received in a socket 98 in a block 99 from which the guides 92 extend. A grub screw 100, engageable with the ball 96, enables the orientation of the welding machine 21 to be accurately aligned relative to the bores 15, 16. Alternatively, the support unit 90 has a magnetic head 91 mountable on the equipment to be repaired, and a single column 92, which supports the welding machine 21 and drive and feed unit 24, mounted on the head via a knuckle (with movement in two axes) . The column has a pair of arms, fitted with plain insulating bushes to journably support the welding bar 22, with a link means to interconnect the arms so that the bushes are co-axial. The shaft 25 will be mounted on one of the arms. (In a modified embodiment, the column may have a groove or keyway engaged by a key, spigot or the like to ensure that the bushes remain co¬ axial as the arms are slidably moved along the column and locked at selected spacings.) To weld joints in pipelines, the welding bar 22 may be supported in bearings in support blocks mounted on three or four adjustable arms which enable the welding bar 22 to be centred in the pipeline. As no feed is required, the drive and feed unit 24 can be modified by simply replacing the nut with a clamp unit which clamps onto the shaft 25 and has a rotary mounting on the first drive pulley 66. Alternatively, the screw-threaded shaft may be replaced with a plain shaft dimensioned to have a running fit in the bore of the first drive pulley 66. A clamp means can be releasably connected to the plain shaft and housing 65 to prevent linear feed of the drive and feed unit. In addition to the repair of damaged bores in equipment and welding joints in pipelines, the machine can also be used for applying hard-surfacing weld metal to the bores of pipes which are used for carrying abrasive materials (e.g. concrete, mineral washings, slurries) and to build up holes which have been incorrectly machined for re-machining. As the rate and direction of the feed can be varied, and the welding head can be varied, the welding head can be provided at either end, or intermediate the length of the welding bar, a wide range of bore diameters can be welded or annular faces (e.g. on flanges) built up for machinery. The advantages of the I.D. welding machine over conventional machines include: (a) relatively low cost of manufacture; (b) can be used with any type of portable line boring machine, utilising the existing boring bar support bearings, saving considerable time when setting up; (c) the I.D. welding head can be used with any type of MIG welding machine; (d) the I.D. welding head may enter the welding bar 22 (slotted brass tube) from either end and may protrude from either end or at any point along the bar through the slots 23 - this provides unprecedented flexibility in terms of setting up to undertake the type of work likely to be encountered (e.g. where there is a series of bores in line to be welded, set up time is markedly reduced) ; (e) when using a support frame, set up time for single holes in any position is markedly reduced; and (f) the design of the rotary drive and feed unit 24 incorporating the disengageable ball screw nut and drive coupling also provides considerable flexibility and time savings when setting up. Various changes and modifications may be made to the embodiments described and illustrated without departing from the scope of the present invention defined in the appended claims.

Claims: CLAIMS 1. An internal diameter (I.D.) welding machine for the repair of bore(s) on equipment including: a tubular welding bar, to extend through the bore(s) to be welded, rotatably journallable in bearings on support brackets on the equipment; means to connect the bar to a rotary drive and feed unit; a welding head mounted in, and extending through, a slot in the bar, or from one end of the bar; and welding gas, wire and/or electricity supply means connected to the welding head and extending through the bar to an end, or the other end thereof. 2. A welding machine according to Claim 1 wherein: the welding bar has a plurality of elongate slots along its length; insulating bushes or support sleeves are provided on the welding bar to rotatably journal the welding bar in pillar block bearings on the support members; and an insulating block or pulley connects the welding bar to the rotary drive and feed unit. 3. A welding machine according to Claim 1 wherein: the welding head is of the MIG-welder of the gasless wire type, flux-cored wire type or gas-shield type, the head having a body on which a welding tip (and any extensions) is angularly adjustable to suit different internal diameters to be welded. 4. A welding machine according to Claim 1 wherein: the welding wire, electrical cable and gas tube enter the tubular body at an end spaced from the welding head. 5. A welding machine according to Claim 4 wherein: a cable connector, within the tubular welding, has a plurality of bores to receive the ends of respective strands of the electric cable; an electrical brush assembly transfers electrical current from the cable connector to a pivot body on which the welding head is mounted; and the cable connector and the pivot body are electrically insulated from the welding bar by insulating spacers or sleeves. 6. A welding machine according to Claim 5 wherein: spring means urge the cable connector and brush assembly into rotating, electrical contact, the spring means being electrically insulated from the cable by which it is surrounded. 7. A welding machine according to Claim 6 wherein: the welding wire extends through co-axial bores in the cable connector and a pivot tube mounted in the pivot body to the tip of the welding head. 8. A welding machine according to Claim 7 wherein: the gas tube is connected to a passage through pivot tube and through ports in a gas diffuser block in the pivot body. 9. A rotary drive and feed unit suitable for an I.D. welding machine, a line boring machine or the like including: a screw-threaded shaft mountable on a support; a drive housing; a nut rotatably mountable in or on the drive housing in operable engagement with the shaft; a drive coupling, operably connectable to the machine to be driven, rotatably mounted in or on the drive housing; 5 a motor mounted in or on the housing; and drive means driven by the motor to drive the nut and the drive coupling; so arranged that as the drive coupling rotatably drives the machine, the nut moves the drive 10 housing along the shaft to feed the machine in a linear direction. 10. A unit according to Claim 9 wherein: the nut has a guide sleeve connected to a first drive pulley operably connected to the motor, and 15 an engaging sleeve slidably mounted on the guide sleeve, the nut being selectively disengageable from the shaft by balls received in bores in the guide sleeve and lockable into engagement by longitudinal movement of the engaging sleeve on the guide sleeve. 20 11. A unit according to Claim 10 wherein: the first drive pulley is rotatably joumalled in bushes in the housing and the nut is releasably mounted on the first drive pulley. 12. A unit according to Claim 9 wherein: 25 the drive coupling is releasably mounted on one side of a second drive pulley rotatably joumalled in bushes in the housing. 13. A unit according to Claim 12 wherein: the drive coupling is operably connectable 30 to the machine to be driven by spring-loaded balls releasably engageable in holes on sockets in the machine. 14. A unit according to Claim 10 or Claim 12 wherein: " 5 the first and second drive pulleys are of electrically insulating material. 15. A unit according to Claim 10 and Claim 12 wherein: the first and second drive pulleys are connected to a driven pulley on the motor by a toothed timing belt. 16. A unit according to Claim 9 wherein: the motor is a reversible variable speed electric motor or is a reversible electric motor controlled by a variable speed controller. 17. A welding machine assembly comprising the welding machine of any one of Claims 1 to 8 in combination with the unit of any one of Claims 9 to 16. 18. An assembly according to Claim 17 and further including: a support unit having an magnetic head releasably mountable on the machine to be repaired, guide means on the head with adjustably mounted pillar block bearings to rotatably journal the welding bar, and means on the head to support the shaft of the unit in parallel to the welding bar. AMENDED CLAIMS [received by the International Bureau on 14 September 1992 (14.09.92); original claims unchanged; new claims 19-22 added; (2 pages)] electrically insulating material. 15. A unit according to Claim 10 and Claim 12 wherein: the first and second drive pulleys are connected to a driven pulley on the motor by a toothed timing belt. 16. A unit according to Claim 9 wherein: the motor is a reversible variable speed electric motor or is a reversible electric motor controlled by a variable speed controller. 17. A welding machine assembly comprising the welding machine of any one of Claims 1 to 8 in combination with the unit of any one of Claims 9 to 16. 18. An assembly according to Claim 17 and further including: a support unit having an magnetic head releasably mountable on the machine to be repaired, guide means on the head with adjustably mounted pillar block bearings to rotatably journal the welding bar, and means on the head to support the shaft of the unit in parallel to the welding bar. 19. (new) A releasable coupling assembly including: a rotatable guide sleeve; and a screw-threaded shaft rotatably joumalled within the guide sleeve; wherein: a plurality of holes, around the guide sleeve, extend radially therethrough at incremental spacings longitudinally therealong; a respective ball is received in each hole; and an engaging sleeve is slidably mounted on the guide sleeve for longitudinal movement therealong between an engaged position, where the engaging sleeve urges the balls inwardly into driving engagement with the shaft, and a disengaged position, where the balls are allowed to "float" in the holes to enable the guide sleeve to be moved longitudinally relative to the shaft. 20. (new) A coupling assembly according to Claim 19 wherein: the holes extend around the guide sleeve to match the pitch of the shaft. 21. (new) A coupling assembly according to Claim 19 or Claim 20 wherein: a pair of external grooves are provided around the guide sleeve; and at least one spring-loaded ball on the engaging sleeve is located in one of the grooves when the engaging sleeve is in the engaged and disengaged position. 22. (new) A coupling assembly according to Claim 19 wherein: the engaging sleeve has an internal recess or groove aligned with the holes, when the engaging sleeve is in the disengaged position, to allow the balls to be retracted into the guide sleeve to release the connection between the guide sleeve and the shaft.

Inventors: HARRIS ASHLEY JAMES, SPITHILL PAUL ALAN, HARRIS, ASHLEY, JAMES, SPITHILL, PAUL, ALAN
Applicants: SKILTEC ENGINEERING PTY LTD, SKILTEC ENGINEERING PTY. LTD.
Application year: 1992
Main classification: B23K37
IPC codes: B23B47, B23K9, B23K37, B23K101, F16H25