WO1992005914A1

WO1992005914A1 - Welding machine and associated equipment

Info

Publication number: WO1992005914A1
Application number: PCT/AU1991/000462
Authority: WO
Inventors: Daniel O'connell Madden
Original assignee: Holcan Constructions Pty. Ltd.
Priority date: 1990-10-09
Filing date: 1991-10-09
Publication date: 1992-04-16

Abstract

A welding machine (10) for the welding of the stubs (27) of anode rods (24) as a turning jig (11) with an elongate bed (12). One end (15) of the anode rod (24) is engaged in tubular or clamp-like coupling rotated by a variable speed motor (16). The other end (19) of the anode rod is supported by a tubular support assembly (18) supported on rollers (22) rotatable journalled on the bed (12). A MIG-type welding head (42) is mounted on an adjustable reciprocating support assembly (28) on a box (25) which has clamp means (26) journalled at one end of the box, which engage a stub (27) which has been tack-welded to one of the arms of the anode rod (24). A transfer station to transfer the anode rod to, or from, the welding machine, and a cutting unit to cut the used stubs from the anode rod, is also disclosed.

Description

TITLE: "WELDING MACHINE AND ASSOCIATED EQUIPMENT" BACKGROUND OF THE INVENTION

(1) Field of the Invention

THIS INVENTION relates to a welding machine and associated equipment. The invention is particularly suitable for, but not limited to, the welding of stubs to anode rods.

(2) Prior Art

Anode rods are used in the process of making aluminium. During this process, the stubs are damaged and approximately 10,000 to 30,000 stubs are replaced each year. The stubs must be cut from their anode rods and replaced with new stubs.

Currently, there are two methods for replacement of the stubs:

(a) hand welding; or

(b) friction welding.

Hand welding gives an inconsistent weld quality as it relies on the operator's skills and has a low productivity rate.

A friction welder is a state-of-the-art machine that handles the job with ease but it requires four operators, has a capital cost of approximately AU$3,000,000, and a large maintenance cost. SUMMARY OF THE PRESENT INVENTION

It is an object to provide a welding machine which provides consistent, high quality welds.

It is a preferred object to provide a machine which has a productivity rate of, eg. 60% greater than hand welding.

It is a preferred object to provide a machine which has an overall cost saving up to AU$500,000 per annum compared with a friction welder.

It is a still further preferred object to provide a machine which only requires a single operator. It is a still further preferred object to provide a transfer station to transfer the anode rods to, and from, the welding machine.

It is a still further preferred object to provide a transfer station which can transfer the anode rods from the smelter to a plurality of maintenance areas, including the welding machine.

It is a still further preferred object to provide a transfer station which can support the anode rods so that one or more support plates and/or fittings can be fitted before the anode rods are placed in the welding machine.

Other preferred objects will become apparent from the following description. In one aspect, the present invention resides in a welding machine to weld a workpiece to a holder including: a turning jig to rotatably support the holder; a housing; means to mount the housing on the workpiece when the workpiece is temporarily fixed to the holder; and a welding head on the housing, so arranged that the workpiece is progressively welded to the holder as the holder is rotated by the jig.

Preferably, the turning jig has an elongate bed on supporting legs, which may have rollers or wheels in tracks, rails or guides. At one end, the holder is preferably engaged in a tubular or clamp-like coupling rotated by a variable speed motor.

Preferably, at the other end, the holder is received in a tubular support rotatably mounted on the bed. Preferably, the housing is a box. Preferably, the means to support the housing on the workpiece is a clamp, engageable a it the workpiece, journalled at one end of the box.

Preferably, the welding head is a MIG-type welding head. Preferably, the welding head is mounted on an adjustable reciprocating support assembly in or on the box.

In a second aspect, the present invention resides in a method for welding a workpiece to a holder including: tack-welding the workpiece to the holder; rotatably mounting the holder on a turning jig; mounting a housing, having a welding head, on the workpiece; and progressively welding the workpiece to the holder as the holder is rotated by the turning jig.

Preferably, a transfer station is provided to place the anode rods in the welding machine, wherein the transfer station includes: a base frame; a transfer frame rotatably mounted on the base; means to rotate the transfer frame between at least two positions; and means to releasably secure an anode rod or article to the transfer frame.

The base frame may be mounted on wheels (which may be flanged) to enable the transfer station to be moved along tracks between two or more selected locations, eg. adjacent the welding machine.

Preferably, upright frames or supports are provided at each end of the base frame. Mounting blocks for an axle, or pair of stub axles, about which the transfer frame rotates, may be vertically movable on guides on the end frames, preferably raised and lowered by hydraulic rams. Preferably, the transfer frame has a table to support the anode rods or other articles.

Preferably, clamp means operated by a hydraulic ram. are mounted on a sub-frame on one side of the table. Preferably, the clamp means includes a rocker arm pivotally mounted on a support on the sub- frame, with one end connected to the hydraulic ram and the other end engageable with the anode rod or article. Alternatively, the rocker arm may be mounted on the hydraulic ram and its ends engageable with a stop and the anode rod (or article) respectively.

Preferably, the transfer table is rotated by a hydraulic ram mounted on the transfer frame and operably connected to the axle by a link. Preferably, before the anode rods are supplied to the welding machine, the used stubs are cut from the anode rods using a cutting machine, wherein the cutting machine includes: a pathway or track adjacent the article to be cut; a carriage movable along the pathway or track; a cutting torch mountable in support means on the carriage; and guide means engageable by the cutting torch on the support means to cause the cutting torch to follow a predetermined path as it is moved by the carriage past the article.

Preferably, the pathway or track lies parallel to a tangent to the article, although the pathway or track may be curved as it passes adjacent the article.

The carriage may be mounted on wheels or rollers which run along tracks or are guided by a guideway. The carriage may be self-propelled. Preferably, the support means enable the cutting torch to be adjusted in at least two axes, preferably including the vertical axis. The support means may include clamp means to releasably engage the body of the cutting torch.

The guide means may include a cam and cam follower, a slot-and-pin, a track-and-pin or like means to guide the support means.

BRIEF DESCRIPTION OF THE DRAWINGS

To enable the invention to be fully understood, a number of preferred embodiments will now be described, with reference to the accompanying drawings, in which:

FIG 1 is a perspective view showing an anode rod stub being welded to an anode rod;

FIG 2 shows a damaged stud being cut from the rod;

FIG 3 shows a stud being tack-welded to the rod;

FIG 4 is a perspective view of a stud; FIG 5 is a side view (in part section) showing the stud being welded to the anode rod;

FIG 6 is a side view of the mounting for the welding head;

FIG 7 is a top view corresponding to FIG 6; FIG 8 is a perspective view showing the transfer station and a second embodiment of the welding machine;

FIG 9 is a perspective view of the transfer station with the anode rod raised in the transport position; FIG 10 is an end elevational view of the transfer station;

FIG 11 is a side elevational view of the transfer station;

FIGS 12 and 13 are end elevational views of the rotating ram with the transfer table in its raised and lowered positions, respectively; FIG 14 is a perspective view of the anode rod being welded in the welding machine;

FIG 15 is a perspective view of the unit; and FIG 16 is a top plan view thereof. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG 1, the welding machine 10 of a first embodiment has a turning jig 11 which has an elongate bed 12 on support legs 13, 14. A tubular coupling 15 is rotatably journalled at one end of the bed 12 and is driven by a variable speed electric motor 16 via a belt and pulley drive 17.

A tubular support 18 has a box-section body 19 between end plates 20, 21 rotatably supported on a pair of rollers 22 at the other end of the bed 12. As shown, the post 23 of the anode rod 24 is passed through the tubular support 18 and engaged in the tubular coupling 15 to enable the anode rod 24 to be supported, and rotated, by the turning jig 11.

A box 25 has a cylindrical clamp 26 releasably securable on one of the anode rod stubs 27 tack-welded to the anode rod 24, the clamp 26 being journalled in an end plate 28 on the box.

Referring to FIGS 6 and 7, a pneumatic cylinder 29 is mounted in the box 25. A slide member 30 is slidably mounted in end plates 31, 32 on the cylinder

29 and is connected to the piston rod 33 thereof by a connecting link 34.

A horizontal rack 35 supported on posts 36, 37 on the slide member 30, the posts extending through a slot 38 in the top of the box 25. An arm 39 is adjustably mounted on the rack 35, movable by an adjustment knob 40 and lockable by a bush 41. A MIG- type welding head 42 is releasably mounted on the arm 39 and is connected to an electricity supply and welding wire supply, both not shown. A pneumatic logic circuit 43 controls the pneumatic cylinder 29 and thereby the range of reciprocal movement of the welding head 42 relative to the anode rod 24 and the stub 27. A finger 44 on the piston rod 33 engages a pneumatic valve 45 to limit the advance of the welding head 42 (by retraction of the cylinder 29), while a pneumatic valve 46 on the end of the piston rod 33 engages a screw mounted stop 47 to set the allowable stroke of the piston rod 33 and thereby the reciprocal travel of the welding head 42.

The replacement of an anode rod stud 27 will now be described.

The anode rod 24 is suspended and each damaged stud is cut from its respective anode leg 48 using an oxy-acetylene torch 49.

Referring now to FIG 3, four studs 28 are placed on a table so the anode rod 24 is placed on them and the studs are tack-welded to their respective legs 48. As shown in FIG 4, each stud 27 has a levelled rim 51 to form a V-shaped annular recess 52 with the bottom of its respective leg 48 - see FIG 5.

The anode rod 24 is mounted on the turning jig 11 as shown in FIG 1 and the box 25 is supported on one stud 27 the clamp 26. The screw pivoted stop 47 is rotated to set the pneumatic cylinder 29 at its minimum stroke.

The electric motor 16 is switched on and the anode rod 24 is rotated, the box 25 being suspended from the stud 27. The welding head is switched on and the recess 52 is progressively filled with weld 53. The weld 53 is built up in layers in the recess and the screw mounted stop 47 is periodically adjusted to increase the stroke of the pneumatic cylinder so that the welding head moves across the recess 52 as it is filled with weld 53. When the stub 27 is welded to its leg 48, the clamp 26 is removed and applied to a second stub 27 and the welding step is repeated.

By control of the speed of the electric motor 16 (and thereby the rotational speed of the anode rod 24) and the reciprocal movement of the welding head 42 via the screw mounted stop 47, the operator can ensure that the studs 27 are accurately welded to the legs 48 of the anode rod 24. The machine 10 is more accurate, and faster, than the hand welding of the studs.

The machine can be used in other applications where a workpiece is welded to a holder as the latter is rotated.

The handling of the anode rod to and from the welding machine is more easily achieved using the transfer station of the present invention.

While the anode studs may be cut from the anode rod using a hand-held oxy-acetylene torch, as discussed above, a cutting unit as hereinbefore described may be used for more consistent and accurate removal of the studs.

Referring to FIGS 8 and 14, the welding machine 100 of a second embodiment is generally as described above. The base frame 101 is mounted on flanged wheels 102 on parallel tracks 103. The anode rod 110 has its post 111 supported by a cylindrical support plate 104 on the rollers 105 and is releasably clamped in a coupling 106. The anode rod stubs 112 are welded by the welding unit 107, as hereinbefore described, and the welding machine 100 is controlled by the operator at a remote control box 108.

The transfer station 120 has a base frame 121 with cross-beams 122, 123 connected by parallel side beams 124 and centre beam 125. The base frame is supported on flanged wheels 126 which run on parallel tracks 127 (at right angles to the tracks 103 of the welding machine 100). Upright frames 128, 129 at each end of the base frame 121 have a cross-bar 130, 131 supported by inclined beams 132, 133 and 134, 135. Vertical guide posts 136, 137 interconnect the σross- beams 130, 131 and cross-beams 122, 123.

The transfer frame 138 has a pair of vertical posts 139, 140 guided for vertical movement by rollers 141, 142 between pairs of end plates 143, 144, which are guided by the guide posts 136, 137 and are raised and lowered by hydraulic rams 145, 146 anchored on extensions to the vertical beam 125. The vertical posts 139, 140 are interconnected by a bottom rail 147 and by an axle 148 journalled in bearings 149, 150 at the top of the posts. A transfer table 151 is mounted on top of a box-like frame 152 mounted on the axle 148. A hydraulic ram 153 is mounted on the bottom rail 147 and has its piston rod 154 pivotally connected to a link 155 mounted on the axle 148. By extending the hydraulic ram, the transfer table is moved from a horizontal position (FIGS 2 and 5) to a vertical position (FIGS 8 and 13).

A clamping assembly 156 has a frame 157 extending from one side of the transfer table 151 and has a post 158 which pivotally supports a rocker arm 159 intermediate its length. A ram 160 is mounted on the outer end of the frame 157 and is connected to the outer end of the rocker arm 159, while the inner clamping end 161 engages the anode rod 110 (on the article to be transferred) . The operation of the transfer station will now be described.

After the used stubs 112 have been removed from the anode rods 110, and replacement stubs have been tack-welded to the respective arms 113, the anode rod 110 is placed above the transfer table 151 with an overhead conveyor 170. The rams 145, 146 are raised so that the transfer table engages the anode rod and loosens the chair supporting the anode rod. The ram 160 is extended so that the clamping end 161 of the rocker arm 159 engages one of the arms 113 of the anode rod 110 to clamp the latter to the transfer table 151, and the rams 145, 146 are then lowered. The transfer station 120 is wheeled along the tracks 127 to the junction with the tracks 103 of the welding machine 100.

The rams 145, 146 may be raised or lowered to set the table at the correct height relative to the welding machine 100.

The ram 153 is partially extended to rotate the table 151 through, eg. 60-70° and the support plate 104 is fitted to the post 111 of the anode rod 110. The ram 153 is then fully extended to lay the anode rod in the welding machine and the clamped coupling 106 is secured. The ram 160 is retracted to release the anode rod 110 from the rocker arm 159. The welding machine 100 is welded along its tracks 103 away from the transfer station 120 and each anode stub 112 is welded in turn as described in the specification in Schedule B.

When the welding has been completed, the operation is reversed and the now repaired anode rod can be wheeled adjacent the smelter on the transfer station and reinstalled using the crane 170.

The transfer station provides a simple, yet highly efficient means of transferring the anode rods to and from the welding machine 100, and between various repair stations. The anode rod 110 has at least one anode stub

112 which is to be cut from the arm 113 to enable replacement with a new stub.

The cutting unit 220 is mounted on a bench 221 which may be fixed to a post or portal frame 222. The bench 221 has a horizontal table 223 with a pair of spaced, parallel guide rails 224, 225 which are engaged by wheels 226 on a carriage 227. The wheels 226 are driven by an electric motor (not shown) connected to an electricity source by a cable 228.

A mounting block 229 is received between a pair of side plates 230 which journal a shaft 231 with a knob 232. The shaft 231 has a pinion (not shown) which engages a rack 233 down one side of a slot 234 in the mounting block 229, the rotation of the shaft 231 by the knob 232 raising or lowering the mounting block 229 relative to the carriage 227.

A mounting plate 235 on the mounting block 229 pivotally supports a pair of parallel links 236, 237 which are pivotally connected to a mounting plate 238 which has an adjustable clamp 239 which releasably engages the body 230 of the cutting torch 231. A knob

242 enables the clamp 239 to move the torch 231 laterally relative to the carriage 227. Gas hoses 242,

243 connect the torch 241 to oxygen and acetylene supply bottles (and regulators) not shown. A pin 244, acting as a cam-follower, is received in a substantially flattened S-shaped slot 245 in the table 223.

The operation of the unit will now be described. The unit 220 is assembled and an anode rod

110, from which a stub 112 is to be cut, is suspended adjacent the unit. The torch 241 is ignited with a cutting flame 246. As the carriage 227 is advanced (ie. moved to the left in the drawings), the pin 244 following the slot 245 causes the torch 241 to be moved laterally to the right hand side of the carriage. When the flame 246 strikes the stub 112, it must first heat the stub before the cutting action will occur. The flame commences to cut the stub 112 and the carriage 227 is advanced. The slot 245 "retracts" the torch 241 so that it moves parallel to the periphery of the stub 112 so that even cutting will occur. Past the midway point, the slot 245 again "extends" the torch 241 but it does not fully flow the periphery of the stub as there is less metal to cut and the body of the stub has now been heated.

When the carriage 227 has completed overpass, the stub 112 has been cleanly cut from the anode rod 110.

The unit provides a simple, adjustable, efficient means to cut the stubs 112 from the anode rods

10 and is readily acceptable to cutting other articles, particularly where the cutting torch requires guidance to follow a contour.

The invention provides an integrated system for the replacement of the anode stubs on anode rods, and the individual machines for the replacement procedures.

Various changes and modifications may be made to the embodiments described and illustrated without departing from the present invention.

Claims

CLAIMS:

1. A welding machine to weld a workpiece to a holder including:

_ turning jig to rotatably support the holder; a housing; means to mount the housing on the workpiece when the workpiece is temporarily fixed to the holder; and a welding head on the housing, so arranged that the workpiece is progressively welded to the holder as the holder is rotated by the jig.

2. A machine according to Claim 1 wherein: the turning jig has an elongate bed on supporting legs; at one end of the bed, the holder is engaged in a tubular or clamp-like coupling rotated by a variable speed motor; and at the other end of the bed, the holder is received in a tubular support rotatably mounted or supported on the bed.

3. A machine according to Claim 2 wherein: the legs have rollers or wheels running in or on tracks, rails or guides.

4. A machine according to any one of Claims 1 to 3 wherein: the housing is a box; and the means to support the housing on the workpiece is a clamp, engageable about the workpiece, journalled at one end of the box.

5. A machine according to Claim 4 wherein: the welding head is a MIG-type welding head mounted on an adjustable reciprocating support assembly in or on the box.

6. A machine as claimed in any one of Claims 1 to

5 and further including a transfer station to transfer anode rods to, and from, the welding machine, wherein the transfer station includes: a base frame; a transfer frame rotatably mounted on the base; means to rotate the transfer frame between at least two positions; and means to releasably secure an anode rod or article to the transfer frame.

7. A machine as claimed in Claim 6 wherein: the base frame is mounted on wheels to enable the transfer station to be moved along tracks between two or more selected locations, one selected location being adjacent the turning jig.

8. A machine according to Claim 6 or Claim 7 wherein: upright end frames or supports are provided at each end of the base frame; mounting blocks for an axle, or a pair of stub axles, about which the transfer frame rotates, are vertically movable on guides on the end frames, raised and lowered by hydraulic rams; and the transfer frame has a transfer table to support the anode rods or other articles.

9. A machine as claimed in Claim 8 wherein: clamp means operated by a hydraulic ram are mounted on a sub-frame on one side of the table, the clamp means including a rocker arm pivotally mounted on a support on the sub frame with one end connected to the hydraulic ram and the other end engageable with the anode rod or article.

10. A machine according to Claim 8 wherein: clamp means operated by a hydraulic ram, are mounted on a sub-frame at one side of the table, the clamp means including a rocker arm mounted on the hydraulic ram with its ends engageable with a stop and the anode rod or article, respectively.

11. A machine according to any one of Claims 8 to 10 wherein: the transfer table is rotated by a hydraulic ram mounted on the transfer frame and rotatably connected to the axle, or a pair of stub axles, by a link.

12. A machine as claimed in any one of Claims 1 to 11, and further including a cutting machine to cut used stubs from the anode rods, wherein the cutting machine includes: a pathway or track adjacent the article to be cut; a carriage movable along the pathway or track; a cutting torch mountable in support means on the carriage; and guide means engageable by the cutting torch on the support means to cause the cutting torch to follow a predetermined path as it is moved by the carriage past the article.

13. A machine according to Claim 12 wherein: the pathway or track lies parallel to a tangent to the article, the pathway or track being curved as it passes adjacent the article.

14. A machine according to Claim 12 or Claim 13 wherein: the carriage is mounted on wheels or rollers which run along tracks or are guided by a guideway.

15. A machine according to Claim 14 wherein: the carriage is self-propelled.

16. A machine according to any one of Claims 12 to 14 wherein: support means enable the cutting torch to be adjusted in at least two axes.

17. A machine according to Claim 16 wherein: the cutting torch is adjustable in the vertical axis; and the support means includes clamp means to releasably engage the body of the cutting torch to enable the cutting torch to be moved towards, or away from, the article.

18. A machine according to any one of Claims 12 to 17 wherein: the guide means includes a cam and cam follower, a slot and pin, a track and pin, or like means to guide the support means.

19. A machine to weld a workpiece to a holder substantially as hereinbefore described with reference to FIGS 1, 5, 6 and 7 of the accompanying drawings; or FIGS 5, 6, 7, 8 and 14 of the accompanying drawings.

20. A method for welding a workpiece to a holder including: tack-welding the workpiece to the holder; rotatably mounting the holder on a turning ig; mounting a housing, having a welding head, on the workpiece; and progressively welding the workpiece to the holder as the holder is rotated by the turning jig.

21. A method of welding a workpiece to a holder substantially as hereinbefore described with reference to FIGS 1, 5, 6 and 7 of the accompanying drawings; or FIGS 5, 6, 7, 8 and 14 of the accompanying drawings.