IES980884A2 - Method of manufacturing excavator buckets - Google Patents

Abstract

The manufacture of excavator buckets is automated. In the case of lightweight buckets the shell and stiffening member may be made as just one integral component. In the case of heavier buckets the shell and stiffening member may be made of two components. <Fig. 1>

Description

Method of manufacturing excavator buckets The manufacture of excavator buckets is automated. In the case of lightweight buckets the shell and stiffening member may be made as just one integral component. In the case of heavier buckets the shell and stiffening member may be made of two components.

TOJ£ COPY AS 5®30β84 lodged METHOD OF MANUFACTURING EXCAVATOR BUCKETS Field of the Invention The present invention relates to a method of manufacturing excavator buckets.

An excavator bucket typically comprises a curved bucket shell; a pair of bucket side walls, one at each side of the shell; a reinforcing member across the top of the bucket shell, the top being the part of the bucket which is attached to the boom of the vehicle and transmits the movement of the boom and is therefore most subject to stress; detachable bucket teeth for attachment to the lower edge of the bucket shell; and a variety of other components.

Prior Art The traditional methods of manufacturing excavator buckets are either manual or semi-automatic. This is because excavator buckets comprise a number of different components, each of these is made separately, these are then joined together, and each welding process is carried out individually, because it is essential that the welding processes are performed effectively. The traditional methods are very labour intensive, and therefore expensive. Furthermore, a considerable IE 980884 - 2 amount of time elapses between commencement of the manufacture of a bucket, following receipt of an order, and completion of the bucket, ready for delivery.

Object of the Invention An object of the present invention is to provide an improved method of manufacturing an excavator bucket, in particular, an object of the present invention is to provide a more automated method involving less labour and involving a shorter production time.

Summary of Invention - First Aspect In accordance with a first aspect of the invention there is provided a method of manufacturing an excavator bucket in an automated manner, the method including the manufacture of the shell of the bucket and the upper stiffening member as an integral component in the following steps: (a) starting with a rectangular piece of steel, folding back one end of the piece of steel by means of one or more lateral folds; (b) seam welding the free edge of the folded back end to the remainder of the piece of steel so as to provide the stiffening member; (c) bending the remainder of the piece of steel to form the bucket shell.

The invention also provides apparatus for use in carrying out the method of the invention.

Summary of Invention - Second Aspect In accordance with a second aspect the invention provides a method of making an excavator bucket in an automated manner, the method including the manufacture of the shell of the bucket and the upper stiffening member in two pieces which are subsequently joined together in the following steps: IE 980884 - 3 (a) starting with a rectangular piece of steel, folding back one end of the piece of steel by means of one or more lateral folds; (b) seam welding the free edge of the folded back end to the remainder of the piece of steel so as to provide the stiffening member and an extension thereof; (c) starting with another piece of rectangular steel, bending this into a curved shape so as to provide the excavator bucket shell; and (d) joining the two pieces of steel.

The invention also provides apparatus for use in carrying out the method of the invention.

Advantages Both methods involve manufacture of an excavator bucket from a minimum number of pieces and by means of simple operations which lend themselves to automation. The first method is preferred when making lightweight buckets, the second method is preferred when making heavy duty buckets.

Brief Description of the Drawings The invention will now be described more particularly with reference to the accompanying drawings which show, by way of example only, one example of how the first method may be put into practice and one example of how the second method may be put into.practice. In the drawings: Figures la, lb, lc, Id, le and If are side elevations showing successive steps of the first method; Figures 2a, 2b, 2c, 2d, 2e and 2f are side elevations showing successive steps in the second method; and Figures 3 to 10 each show a perspective view of a work station in IE 980884 - 4 an assembly line for producing the excavator, except that Figure 8 shows a tool for use in the workstation of Figure 7.

Detailed Description of the First Method Figure la shows a rectangular piece of flat steel 1, from which the bucket shell and stiffening member will be made.

Figure lb shows the piece of steel 1, including a lateral fold 2 near one end, produced by means of a box forming press which will be described in more detail later.

Figure lc shows the piece of steel 3 including a second fold 3, the fold 3 is produced by a further box forming press.

Figure Id shows the piece of steel 1 including a third fold 4, the fold 4 is produced in a still further box forming press Figure le shows the folded part of the piece of steel clamped in position so that the free edge 5 of the folded back end abuts against the flat part, and a seam weld is carried out so as to permanently join the free edge 5 to the flat part thus forming the reinforcing member. The operation of clamping and seam welding is carried out in a clamping and seam welding work station which will be described in more detail hereinafter.

Figure If differs from Figure le in that the flat part has now been bent into a curve to form the shell of the excavator bucket.

Detailed Description of the Second Method Figure 2a shows a rectangular piece of flat steel 101, for use in making the stiffener element only of a larger excavator bucket.

Figure 2b shows the piece of flat steel, with one lateral fold 102. The fold 102 is produced by means of a hydraulic press.

Figure lc shows the piece of steel 101 with a bend 103 at the lE 980884 - 5 other end. This bend is produced in a hydraulic press.

Figure lc shows the piece of steel 101 with a further bend 104 at the other end, so that the stiffener element is almost formed. The further bend 104 is produced in a hydraulic press.

Figure 2e shows the free edge of the bent over part of the piece of steel engaging the flat part of the steel, following which the free edge is automatically seam welded to the flat part, thereby producing the stiffener. The final operation of bending, clamping in position, and seam welding is carried out in a clamping and welding workstation.

A further flat piece of steel 110 intended to form the main bucket shell, is bent over, this operation is not shown in the drawings.

Figure lf shows the stiffener and the bucket shell being joined together, this operation is carried out in a welding station which will be described in more detail hereinafter.

Other Steps in First and Second Methods It will be appreciated that other components need to be joined as well, for example side walls, excavator teeth, cutting edges, wear resistant straps etc. These are relatively simple operations which may be carried out manually, semi-automatically or automatically at other workstations.

Description of Workstations Box Forming Presses (Three) - Figure 3 These three workstations are used in the first method to carry out the three folding operations.

A base consists of a pair of horizontal steel beams 201, 202, one above the other, each beam having a length of approximately two metres, and the overall height of the base being a little less than one metre. At each side of the base (each end of the pair of beams which form the base), a vertical side column 203 is provided, these are approximately IE 980884 - 6 3.5 metres in height. A horizontal top cross beam 205 or gantry is mounted at the top of the two columns 203 and is especially reinforced to give minimal deflection under load. The underside of the top beam 205 includes a mounting for an array of downwardly vertically extending hydraulic cylinders 206 which are mutually equi-spaced along the length of the horizontal top cross beam 205· A horizontal boom 207 is provided between the top beam 205 and the base 201, 202. The boom 207 is of substantial depth. The upper region of the boom includes pin locators 208 for each one of the hydraulic cylinders 206. The lower region of the boom 207 includes bolt holes for receiving bolts 209 used to fasten tooling 210 to the boom. The upward and downward movement of the boom 207 is effected by operation of the hydraulic cylinders 206. The movement of the boom 207 is constrained to the vertical direction by means of a rack and pinion arrangement, a rack 211 is provided on each column 203, and a horizontal shaft 212 externally mounted on the boom 207 is provided with a pinion 213 at each end for co-operation with the corresponding rack 211. Depth stops (not shown) are fitted to the boom 207 of the press to control the depth to which the workpiece is formed.

A jib crane (not shown) is provided on top of the press to enable an operator to lift steel plates which have been cut to size onto the base. The jib crane includes a vacuum suction unit which lifts one section of plate from a stack of plates.

The press as described in the preceding paragraph is one of a bank of five machines which together form a production line for the forming of small capacity buckets. The line includes three hydraulic presses of the type described, a clamping and seam welding press (described below), and a bucket assembly press.

In operation of the production line, an operator lifts a cut-to-size plate from a stack of steel plates, making use of a jib crane including vacuum lift, this operator lowers the workpiece onto two channel section beams 214, raises the boom 207, and moves the workpiece along the two channel section beams 214 into the workstation. As the workpiece moves along the beams it passes over and depresses two weighted spring up stops 215. Further movement of the workpiece beyond the stops 215 allows the stops 215 to spring up again and the workpiece IE 980884 - 7 is then reversed so as to abut against the spring up stops 215. The workpiece is thus positioned. The position of the stops 215 is adjustable. This form of positioning mechanism is used in some of the other workstations also. The operator then brings the boom 207 down until the boom stop bottoms out, thereby producing the first fold. The boom 207 is then retracted upwardly- The plate is moved along to the second press which produces the second fold in like manner. The plate is then moved to the third press which produces the third fold. The plate is then moved to the clamping and seam welding press. Finally, the plate is moved to the bucket assembly press.

Combined Seam Welder and Clamping Press - Figure 4 This workstation is used in the first method to carry out the clamping step and is similar to the clamping press, described in more detail later, used in the second method, but welding is carried out on an automated basis.

A rectangular frame consists of a horizontal lower beam 250, a horizontal upper beam 251, and a pair of vertical columns 252. The press is approximately 2.5 metres wide and 1.5 metres high. A horizontal boom 253 is located between the upper beam 251 and the lower beam 250 so as to be moveable vertically upwardly and downwardly. Movement of the boom is effected by means of three hydraulic cylinders 254 mounted in a channel 255 in the lower beam 250, and connected to the lower face of the boom 253. The boom 253 is constrained to movement in the vertical direction by means of rollers 256 at each end of the boom which run in guide rails 257 on the upright columns. The upper beam 251 is provided on its top face with a rail 258 in the form of an aluminium extruded section, and on this rail 258 there is a carriage 259 movable by means of a variable speed electric motor, and supporting a metal inert gas (MIG) carbon dioxide electric welder torch 260. A further higher rail 261 is provided which holds the electric welder cables 262 and enables the cables to move along the length of the seam weld during the welding operation. A welder wire feed unit (not shown) is mounted on a double arm linkage jib which allows the wire feed unit to articulate during the welding operation. The stop and start positions for the electric welder torch 260 are IE 980884 - 8 determined by means of sliding contacts 262 mounted on a further rail 263 in front of the upper beam 251. The limit of travel of the variable speed motor 259 is set by limit switches 264 on the rail 258 which supports the electric welder torch 260.

In operation, the boom 253 is lowered to accommodate the workpiece, in this case a partially open section. The workpiece is inserted into the press and is located by means of the spring-up stops. The operator then activates the switch for the hydraulic cylinders 254 to move the boom 253 upwards and thereby clamp the workpiece, closing the gap in the workpiece. The electric welder torch 260 is then manually lined up with the weld joint, at one end thereof. The electric welder torch 260 is then manually switched on, and welding takes place automatically along the length of the seam. At the end of the seam, limit switches 262, 264 are tripped automatically stopping both the welder torch 260 and the variable speed motor 259.

Bevelling Machine - Figure 5 This workstation is used for both methods of the invention to provide a sharp cutting edge for the leading edge of the buckets.

A horizontal steel cross beam 300, approximately 2.5 metres in length, is mounted on two spaced apart uprights 301. The latter include stabilising supports 302 with leveling screws 303 so that the cross beam 300 may be set exactly to the horizontal. Just below the cross beam 300, there is a horizontal conveyor, mounted on the uprights 301, and consisting of a series of rollers 304 arranged to allow a rolling motion from one side of the bevelling machine to the other side of the bevelling machine, along the conveyor in a direction from one upright 301 towards the other upright 301. A number of linkages 305 are provided which rotate through 90° in a vertical plane as indicated by arrows so that a flat bar (not shown) placed on the conveyor so as to lie in a horizontal plane can be picked up by the linkages 305 and rotated to the vertical position. The linkages 305 are operated by means of hydraulic cylinders (not shown). Mountings (not shown) are provided for the hydraulic cylinders, the mountings are secured to the cross beam 300, and the linkages 305 extend downwards Έ980884 - 9 between pairs of adjacent rollers and in operation are pivoted upwards from between the rollers 304. A trough 306 for collecting metal shavings is removably arranged below the conveyor. An extruded aluminium section 307, mounted on a housing support at the rear of the cross beam 300, serves as a guide rail for the carriage of a variable speed electric motor 308 which drives the cutting torches 309. At each end of the horizontal cross beam 300 there are upwardly projecting brackets 310, and these support between them a guide rail 311 which supports and guides a sliding carriage 312 on which the cutting torch 309 is mounted. The sliding carriage 312 includes a protractor (not shown) to alter the bevel angle of the cutting torch 309. At one side of the bevelling machine there is a control panel 313, from this panel it is possible to activate solenoid valves to open and close the oxygen and gas supply to the cutting torch 309 and it is possible to activate the variable speed motor 308.

In operation, the workpiece, in this case a flat steel bar (not shown), is placed flat on the conveyor. The hydraulic cylinders are operated as a result of which the linkages 305 pivot upwardly between the rollers 304, engage the flat steel bar from underneath and rotate the flat bar from the horizontal to the vertical. The cutting torch 313 is moved manually to one end of the flat steel bar. The angle of the cutting torch 313 is selected manually. The flat steel bar is then preheated. After the flat steel bar has been preheated, the variable speed motor 308 is switched on, and the carriage 312 and the cutting torch 313 move along the edge to be bevelled, thereby producing the bevelled edge. Limit switches (not shown) are provided which are tripped when the cutting torch 313 reaches the end of the flat steel bar, and as a result the variable speed motor 308 and the cutting torch 313 are both stopped.

Seam Welder for Welding Bucket Side to Side Cutter - Figure 6 This workstation is used for the first method of the invention to attach a cutting edge (side cutter) to the side wall of the bucket.

A steel framework consists of a horizontal base_350, two vertical uprights 351, and an open-frame planar support platform 352 *E 980884 - 10 eccentrically pivotally mounted about a horizontal axis between the two uprights 351. The support platform includes support straps (not shown) to hold the bucket side and the bucket side cutter section in position. The support platform also includes toggle clamps (not shown) for fixing the side cutter in position and a removable stay arm (not shown) for securing the bucket side in position and a retractable rotating stop (not shown) for aligning the bucket side to the side cutter for the seam welding operation. The workstation includes two further uprights 353, a rail 354, sliding carriage 355, variable speed motor 356 for driving the carriage 355 along the rail 354, torch welder mounting 357 on the carriage and welding torch 359.

In operation the planar open-frame support platform is rotated so as to present first one face and then the other face of the bucket side wall and side cutter to the automatic welding torch 354.

Hydraulic Press (Deep Stroke) - Figure 7 This workstation is used in the second method to carry out the bending and folding operations.

A base is constructed of two mutually parallel spaced apart upright heavy gauge steel plates 401 and large transverse steel beams 402 extending between the two upright plates. Four columns 403, which are of large cross-section and which are made of steel, are arranged one at each corner of the base. A roof section 404 is mounted at the top of the four columns 403, and is similar in construction to the base. Three hydraulic cylinders 405, which are large heavy duty double acting cylinders, are mounted on the underside of the roof. A boom 406 is mounted between the roof 404 and the base, for upward and downward movement. The raising and lowering of the boom 406 is effected by the three double acting hydraulic cylinders 405. The boom 406 is constrained to movement in the vertical direction and is guided in such movement by means of a rack and pinion arrangement, consisting of a vertically extending rack 407 on each column, and corresponding bevel gears 408 on the boom. The hydraulic cylinders 405 rams are operated from a hydraulic power pack (not shown) consisting of a reservoir of hydraulic fluid containing forty gallons, and two hydraulic pumps in IE 980884 - 11 series. One pump is a high flow low pressure pump for rapid movement of the boom 406 towards a workpiece. The other pump is a low flow high pressure pump for slow movement of the boom 406 when engaged with the workpiece so as to form the workpiece. The hydraulic system further includes an hydraulic filter, hydraulic gauges, hydraulic pipes, and manually or electrically operated hydraulic spool valves. The lower side of the boom 406 may receive various tools for producing various different buckets.

Tooling for Hydraulic Press (Deep Stroke) - Figure 8 An example of tooling which may be used in the hydraulic press will now be described. An upper tool 450 for mounting on the lower side of the boom 406 has a profile of a V-on-its-side, the lower arm 451 has a radiussed tip 452 and the tool has a travel of approximately 75 cm. A lower tool 453 for mounting on top of the base 401, 402 has an upright V-profile. The lower tool consists of two mutually parallel spaced apart horizontal hardened steel bars 454, 455, each capable of rotating about its axis during the forming process. A workpiece (not shown) is introduced into the press along a support framework or rails consisting of two channel section beams (not shown), these include weighted spring-up stops (not shown) so that the workpiece is correctly located in the press. Further stops (not shown) are provided to control the depth to which the radiussed tip 452 of the upper tool 450 projects into the V-profile lower tool 453.

In operation of the press of Figure 7 and the tool of Figure 8, the hydraulic cylinders 405 are first operated to raise the upper tool 450, a generally rectangular piece of steel is moved into position, and the hydraulic cylinders 405 are then operated to lower the upper tool 450 until it meets the vertical stops. The position of the vertical stops is adjustable.

The use of an upper tool 450 having a V-on-its-side profile allows the radiussed tip 452 of the tool to penetrate an already partially folded piece of steel to carry out the final folding operation. As may be seen in Figures 1 and 2, the final fold must still leave a gap for the tip 450 of the tool to be withdrawn. The clamping step therefore IE 980884 - 12 includes forming so as to close the remaining gap.

The use of a lower tool 453 consisting of bars 454, 455 which can rotate improves the finish of the formed workpiece. As the upper tool 450 descends between the two bars 454, 455 of the lower tool 453, the material of the workpiece which-is resting on the bars 454, 455 is drawn into the region between the two bars, and the bars rotate correspondingly thus reducing any friction.

Clamping Press - Figure 9 This workstation is used in the second method to carry out the clamping step so as to permit tack welding.

The clamping press consists of a generally upright rectangular frame consisting of an elongate horizontal base 500, an upright column 501 at each end of the base, and a horizontal top cross beam. An elongate horizontal boom 503 is movable in the vertical direction between the base 500 and the top cross beam 502 . Movement of the boom 503 in the upward and downward direction is effected by means of three hydraulic cylinders 504 mounted in a channel 505 at the base of the press. The movement of the boom 503 is constrained by side rollers 505 at each side (end) of the boom 503 running in tracks 507 on the upright columns 501. The top face of the boom 503 is provided with a continuous row of hardened steel rollers 508 which enable the work piece to roll from side to side (end to end) within the clamping press. This play minimizes shearing forces and consequent scuffing of the material and improves the finish. The hydraulic cylinders 504 are operated from an external hydraulic power source (not shown).

In operation, the hydraulic cylinders 504 are operated to lower the boom 503 sufficiently to accommodate the workpiece between the boom 503 and the top cross beam 502. The hydraulic cylinders 504 are then operated in the reverse direction to raise the boom 503 so as to firmly clamp the workpiece between the boom 503 and the top cross beam 502.' When the workpiece is firmly clamped, the workpiece may be manually tack welded.

IE 980884 - 13 Telescoping Rig - Figure 10 This workstation is used in the second method to form the bucket shell and to join the bucket shell to the bucket side walls.

A base frame or platform 550 is provided for supporting an excavator bucket 700. A gantry is provided over the base frame, the gantry consists of two side support arms 551 and a horizontal cross beam 552. The side support arms 551 are telescopic in length. Furthermore, the side support arms 551 are pivotally moveable through approximately 150° centred on the vertical. A hydraulic cylinder (not shown) is provided in each telescopic side support arm 551 to effect the telescopic movement. A further hydraulic cylinder (not shown) is provided at the base of each side support arm 551 for effecting pivotal movement of the arm.

In use, the side support arms 551 are telescoped outwardly a sufficient distance to receive the workpiece between the horizontal cross beam 552 and the platform 550. In this case, the workpiece consists of two approximately semi-circular excavators bucket side walls 701 which are placed in an upright position, mutually spaced apart, and with their flat edges resting on the platform, and a pre-rolled bucket shell 702 which is fitted over the bucket side wall 701. The telescoping rig is used to compress the bucket shell against the bucket side walls 701. The horizontal cross beam 552 may be moved along the contour of the curved edge of the bucket side walls 701, contact dollys 703 pressing the pre-rolled shell 702 against the edges of the side walls 701, so that welding may take place. Initially, the cross beam 552 is lowered and pivoted so as to bring one end of the pre-rolled bucket shell 702 into contact with one end of the curved edges of the bucket sides 701, and welding takes place at each point of contact. Thereafter, the pair of hydraulic cylinders for telescoping the arms 551 and the pair of hydraulic cylinders for pivoting the arms 551 are each operated so as to enable the cross beam 552 to slowly move along the contour of the bucket towards the other end. All the while, welding is taking place so that the bucket side walls 701 are connected to the bucket shell 702.

IE 980884 - 14 When this operation has been completed, the telescoping rig may be used in like manner in the further step of securing bucket wear straps, shown in the Figure.

IE 980884

Claims (4)

1. A method of manufacturing an excavator bucket in an automated manner, the method including the manufacture of the shell of the bucket and the upper stiffening member as an integral component in the following steps: (a) starting with a rectangular piece of steel, folding back one end of the piece of steel by means of one or more lateral folds; (b) seam welding the free edge of the folded back end to the remainder of the piece of steel so as to provide the stiffening member; (c) bending the remainder of the piece of steel to form the bucket shell.

2. A method of making an excavator bucket in an automated manner, the method including the manufacture of the shell of the bucket and the upper stiffening member in two pieces which are subsequently joined together in the following steps: (a) starting with a rectangular piece of steel, folding back one end of the piece of steel by means of one or more lateral folds; (b) seam welding the free edge of the folded back end to the remainder of the piece of steel so as to provide the stiffening member and an extension thereof; (c) starting with another piece of rectangular steel, bending this into a curved shape so as to provide the excavator bucket shell; and (d) joining the two pieces of steel. IE 980884

3. A method of manufacturing an excavator bucket is an automated manner 5 substantially as hereinbefore described with reference to and as illustrated in Figure 1 and 3 to 10 of the accompanying drawings.

4. A method of manufacturing an excavator bucket is an automated manner substantially as hereinbefore described with reference to and as illustrated in Figure 2 to 10 10 of the accompanying drawings. IE 980884 (A) Figure 1 ( B) (C) (D) (E) (F) IE 980884