Abstract:
A bucket for a front end loader is formed with a minimum number of parts so that it can easily be assembled held in fixtures and welded with robot welders. The bucket includes a unitary panel that forms a bottom wall and a rear wall, with a curved junction wall between the bottom and rear walls. An integral top rail is formed at the upper edge of the rear wall for structural integrity. The formed top rail is made with a sloped top rail wall to increase the visibility of a load in the bucket to an operator in a cab of a skid steer loader. The bucket walls and parts which weld thereon have locating tabs and mating edges for locating the parts automatically, so that they can be welded into position. The bucket is made with brackets for mounting it onto a quick attachment plate of a skid steer loader.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority on prior copending United States provisional application Ser. No. 60/104,183, filed Oct. 14, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a bucket construction for a bucket of a front end loader, which is made in a manner that permits automated or robot assembly and final welding of the parts and subassemblies. 
     Prior art buckets for front end loaders are generally welded assemblies, which require a large amount of hand welding and assembly, and thus the cost is increased. In many instances the bucket parts and subassemblies are assembled in a manner so that a robot controlled welding head cannot access the desired weld line. 
     The prior art buckets also are made of many individual pieces that require welds for assembly. Thus reducing the number of parts is desirable. 
     SUMMARY OF THE INVENTION 
     The present invention is a bucket for a front end loader that is simplified in construction so that the parts can be handled with robots and tack welded in place. The robots used can hold the critical dimensions of brackets used for the attachment of the bucket to a loader through a quick attach adapter. 
     The number of parts and subassemblies used in the final assembly and welding of the bucket is reduced in part by forming a bucket panel that forms the bottom wall and the rear wall in one piece joined by a curved junction portion. The reinforcing and attachment top rail at the top of the rear wall is formed as a single folded box cross section. After folding or forming the rail requires only an external weld that can be made with a robot welding head. The top rail is made so that it tapers down in a forward direction to increase the visibility of a load to an operator in the cab of a skid steer loader having a bucket made according to the present invention. 
     The bucket walls and parts have locating tabs formed to provide reference edges that are engaged by edges on the part to be located. Outer edges of the parts are used, as well as edges of slots formed for the express purpose of alignment. The parts that need to be manipulated are provided with robot grip attachment holes so the same robot can be used for many different types of buckets. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top front perspective view of the bucket of the present invention; 
     FIG. 2 is a rear perspective view of the bucket of FIG. 1; 
     FIG. 3 is a top plan view of the bucket of FIG. 1; 
     FIG. 4 is a rear elevational view of the bucket of FIG. 1; 
     FIG. 5 is a side elevational view of the right side of the bucket of FIG. 1; 
     FIG. 6 is a side elevational view of the left side of the bucket of FIG. 1; 
     FIG. 7 is a sectional view taken on line  7 — 7  in FIG. 3; 
     FIG. 8 is an enlarged sectional view of a top rail of the bucket of FIG. 1; 
     FIG. 9 is a bottom plan view of the bucket of FIG. 1; 
     FIG. 10 is a fragmentary rear view of a mounting bracket subassembly on a rear wall of the bucket showing locating tabs and edges for locating mounting bracket parts for robot assembly; 
     FIG. 10A is an enlarged sectional view taken on line  10 A— 10 A in FIG. 10; 
     FIG. 11 is a perspective view of a bucket adapter mounting bracket subassembly to show details of the mounting bracket; and 
     FIG. 12 is an exploded view of the parts assembled by robots during the final welding stage. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A bucket  10  is shown assembled in FIGS. 1 and 2 and is made with a minimum number parts and subassemblies and is manufactured by robot methods. The bucket  10  has a main single sheet wrap around panel  12  that forms a bottom panel or wall  14  and an upright rear wall  16 , that joins the bottom wall in a curved junction wall  18 . The rear wall  16  has a plurality of formed tabs  20 A,  20 B and  20 C, (FIG. 2) that are used for locating parts to be attached to the wrap around panel. The tabs  20 A,  20 B and  20 C are used for locating an attachment adapter  22  that is a welded mounting bracket subassembly at the time of final welding and assembly of the bucket. 
     FIG. 12 is an exploded view of the bucket showing the parts that are used in the final welding process. Reference can be made to the Figures as the description proceeds. 
     The rear or back wall  16  of the bucket formed by the wrap around panel  12  inclines forwardly from the curved junction wall  18  and terminates in a formed box section top rail  24 . The top rail  24  can be rolled from the wrap around panel  12  and as best shown in FIG. 8, includes a top curved edge  26  that joins a downwardly and forwardly inclined wall  28  that tapers forwardly at a slope that is designed to increase the ability of an operator on a skid steer loader to see into the interior of the bucket when working. The top rail  24  has a forward wall  30  that is parallel to the rear wall  16 . The forward wall joins a bottom wall  32  that has an edge the engages or is very close to the front or inner surface of the rear wall  16 . In the final welding process, the junction line or seam  34  forming the edge of the bottom wall  32  that engages the front surface of rear wall  16  is welded to rear wall  16  with a welding head operated by a robot. The welding junction line along the edge of the bottom wall is open from below and can be reached by a robot welding head. The weld can extend all the way across the width of the bucket. 
     The bucket wrap around panel or sheet  12  has end plates  38  welded at opposite ends thereof, and the end plates each include the main panel  38 A and the top support panel  38 B, that has a series of holes  38 C that are used for attaching wear plates or extensions panels  40  shown in FIG.  7 . The extension panels are used where less dense material is carried, although the main panels and top support panels, which are welded together, will hold the rated capacity of the loader on which the bucket is intended to be used. The auxiliary or extension panels  40  are optional. The end plates  38 , each including a main panel  38 A and a top panel  38 B are tacked or tack welded as a subassembly prior to the final assembly welding of the parts shown in FIG.  12 . 
     The wrap around panel  12  is the main structural component of the bucket and is used for mounting the rest of the components, including a bar  42  forming a cutting edge which extends all along and under the front edge of the bottom wall  14  of the bucket, which is part of the wrap around panel  12 . The cutter bar  42  has a tapered or sharpened leading edge  44  that extends forwardly of the bottom wall of the bucket. A series of holes  46  that are arranged in fore and aft extending pairs  46 A and  46 B and are used for bolting on teeth shown schematically at  48  in FIG. 7 after the welded assembly is made. The teeth are optional as well and in many applications the cutting edge is used without teeth, particularly when loading or handling loose material. The teeth  48  are used primarily for digging. 
     The wrap around panel  12  is held in a robot fixture and can be manipulated to invert it as needed. The top rail is formed before any assembly so the curved panel  12  with the formed top rail is shown in FIG. 12 before parts are welded to it. 
     The cutter bar  42  is tack welded in place in a first tack welding station after aligning the parts using the holes  46 B which aligned with holes  46 B in the bottom wall  14  (see FIG.  3 ). The bottom wall  14  also has a series of slots  50  formed therethrough which overlie the rear portion of the cutter bar  42 . These slots  50  are used for welding the cutter bar to the bottom wall  14 . This welding at the slots  50  can be a tack weld in initial assembly and full welding can be during final assembly welding of the bucket. The wrap-around panel is held in a robot fixture in a conventional manner as the parts are added to it during the final welding and assembly process. 
     The bottom wall or panel  14  is reinforced using a skid or wear plate  54  that is provided with spaced holes  56  (see FIG. 9) that are spaced for connection to robot grips that pilot into the holes and securely grip the plate  54 . The robot then places the plate  54  on the bottom wall and the plate  54  is tack welded to the bottom wall through slots  57 . 
     The mounting bracket subassembly  22  is mounted on the rear side of the bucket and used with a quick attachment plate on a loader such as a skid steer loader made by Melroe Company of Fargo, N.Dak., and sold under the mark “Bobtach”. Such a quick attachment plate is disclosed in U.S. Pat. No. 3,672,521. The mounting brackets  58  and  60  are initially assembled together with an attachment lip  62  to form the subassembly  22 , and then the mounting brackets in the subassembly are located in portion and tack welded on the back or rear wall  16  of the wrap around panel. This is done right after the cutter bar is tack welded to the bottom wall  14 . 
     The brackets  58  and  60  are right and left hand and each has a flat plate portion  58 A and  60 A and bent up legs  58 B and  60 B on the outer sides. Additionally, the brackets have outwardly bent bottom flanges  58 C and  60 C, respectively. The subassembly is properly located using a robot for holding the subassembly and placing it onto the exterior of the back wall of the wrap around panel. The plate portions  58 A,  60 A have slots  58 D and  60 D that are formed before the legs  58 B and  60 B are bent up so there are slot sections in both the flat plate portions and the legs after the legs are bent. The slots  58 D and  60 D form holes for grippers of the robots used to hold the mounting bracket subassembly  22  for moving it toward and into contact with the outside of the rear wall. The brackets  58  and  60  also have positioning or locator slots  58 E and  60 E formed in the plate portions that have upper edges positioned to provide a reference locator line. The locator slots  58 E and  60 E are used for locating the subassembly  22  vertically on the top edges of locator tabs  20 A and  20 C for tack welding. Both mounting brackets  58 B and  60 B have the slots  58 E and  60 E so the same punched blank can be used for both brackets, and the right and left forms made by bending the legs  58 B and  60 B and the bottom flanges  58 C and  60 C in opposite directions. 
     The rear or back wall  16  of the bucket has the three locator tabs  20 A,  20 B and  20 C partially punched out, as explained. The tab  20 A is positioned to fit into the slot  60 E, and the tab  20 C is positioned to fit in the slot  58 E for vertical positioning of the bracket subassembly, and the tab  20 B is used to locate the upright or vertical edge of one of the brackets, as shown bracket  60 . The three point positioning positively locates the bracket properly. The tabs  20 A,  20 B and  20 C are formed as shown in FIG.  10 A and each partial punch out is made to have a substantially straight, flat edge that engages the surface to be located, so the positioning is accurate. 
     The subassembly  22  then can be tack welded in position, at desired locations, while being held by the robot properly positioned by the alignment tabs  20 A,  20 B and  20 C. 
     The flanges  58 C and  60 C have slots  58 F and  6 OF that are used for lock pins that are on the attachment plate used on the loader. Before final tack welding in place, these slots  58 F and  60 F are used to fit into a jig or fixture so that they are properly spaced and then the bracket subassembly  22  is tack welded in place. 
     The wrap around panel then is inserted and a corner bracket reinforcement or back brace is then placed into position and is best seen in FIG.  7 . Reinforcement angle or back brace  70  is an angle shaped formed piece of metal indicated generally at  70  which has a leg  74  that extends up under the lower portions of the brackets  58  and  60  to brace the ends and reinforce them. The reinforcement is moved up between the rounded corner portion  18 , and the ends of the brackets  58  and  60 . The lower leg  72  of the reinforcement  70  is positioned to engage the rounded corner  18  near its junction with the bottom wall  14 , as shown in FIG. 7 in particular, and is tack welded in place. The bracket  58  is shown partially broken away and in section in FIG.  7 . 
     The lower leg  72  of the reinforcement  70 , as can be seen in FIG. 9, has a pair of robot gripper holes  76 ,  76  which are spaced apart the same distance as holes  56 ,  56  of the reinforcing plate or wear plate  54 . 
     In addition, the lower leg  72  of the reinforcement member  70  has three alignment or locator tabs  75 A,  75 B and  75 C formed thereon. These locator tabs  75 A,  75 B and  75 C are formed in the same manner as that shown in FIG. 10A, and project out from the lower portion of the leg  72  of the reinforcement member  70 . The reinforcement member  70  is tack welded in place after the leg  74  is urged up between the lower ends of brackets  58  and  60  and the bucket rear wall and the edge of leg  72  rests on the lower side of the curved portion  18 . 
     The attachment brackets  58  and  60 , and in particular, the flanges  58 C and  60 C are mated with a lower latch plate assembly  80  that has flanges  82  and  84  on opposite ends thereof, and which are joined by a center member  86 . The assembly of the two flanges  82 ,  84  and the member  86  is indicated at  88 , and this assembly is located in position by the tabs  75 A,  75 B and  75 C. Edges of flanges  84  are engaged by tabs  75 A for end use locating  75 B for fore and aft location. Tab  75 C locates flange  82  in fore and aft direction. It can also be seen that the flange assembly has robot gripper openings  89 ,  89  on the outer edge portions of the flanges  82  and  84 , and these are again spaced the same distance apart as the robot gripper opening  76 ,  76  so the same robot can be used for placing the latch assembly  88  into position against the locator tab  75 A,  75 B and  75 C. 
     Again there are three of the locator tabs for the assembly  88 , so that the assembly can be positively positioned against these tabs while held by a robot gripper, and will be properly located so that latch openings  90  and  92  will be aligned with the slots  58 F and  60 F, so when lock members (not shown) from the quick attachment plate of a skid steer loader, such as that shown in U.S. Pat. No. 3,672,521, which is incorporated herein by reference, are placed into position. The lock member of the attachment plate slots  58 F and  60 F, and into the latch openings  90  and  92 , respectively on the flanges  82  and  84 . 
     This action will positively latch the bucket in place on the attachment plate, once the final assembly welding is done, and securely hold the bucket for working relative to the skid steer loader. The placing of the corner reinforcement  70 , and the assembly  88  onto the wrap around panel, at the rounded corner  18 , is done after the bucket has been inverted, and that is when the plate  54  is also installed. 
     As can be seen, the plate  54  is a formed plate, so that the slots  57 ,  57  are in a channel  59  that is formed in the center portions of the plate  54 . A channel wall  59 A of the formed channel will engage the under surface of the bottom wall  14 , for welding. The edges of the panel or wear plate  54  can be formed, as shown by the wall portion  55 , in FIG. 5, to engage the underside of the bottom wall  14  and the flanges are welded to the bottom wall. 
     Then, the end plates  38  can be placed onto the ends of the wrap around panel to form the bucket. The end plates can be held with suitable suction cups or the like with robots, and placed against the end edges of the wrap around panel, and tack welded in place around the top rail and along the junction with the top rail. 
     Brackets  98  on the top rail are steps that can be used for gaining access to a skid steer loader on which the bucket  10  is mounted. The steps can be added at any time. The front wall  30  of the top rail  24  has a plurality of openings indicated at  100  therein, and these are used for mounting attachments such as a grapple, or the like. In FIG.  4  and in FIG. 6, wrench access openings  102  are shown on the bottom wall  32 , so that bolts that are passed through the openings  100  to secure an attachment in place can be tightened. This is conventionally done in formed box sections. 
     After the parts have been tack welded in place, the final welding can take place with continuous welds along the junction  34 , and continuous welds around the wrap around panel  12  where it joins the end plates  38 . A continuous weld would be used along the front edge  105  of the bottom wall, to weld the cutter bar securely. The corner reinforcing member  70  also can be welded continuously at the edges of legs  72  and  74 , except where leg  74  passes behind the brackets  58  and  60 . These welds are accessible, by having the formed top rail that can be welded with one continuous pass along the junction  34 , and then providing access for robot held welding heads around the periphery. 
     The use of gripper holes that are spaced identically on parts that are attached to the wraparound panel  12  insures that the robots will be easily installed on the parts, and the locator tabs shown make it so that the parts that are going to be welded in place are properly positioned by the tabs and then tack welded prior to final welding. 
     The flanges  58 C and  60 C are welded securely to the flanges  82  and  84  of the assembly  88 . 
     The exploded view of FIG. 12 shows the individual parts that are assembled together, to make the bucket. Sub-assemblies are made of the side plates and extensions and the attachment bracket, as stated, the cutter bar is tack welded into position using the slots  50  on the top plate, and the bracket subassembly  22  is put into place on the back wall, the wrap around panel is inverted, and the reinforcing corner  70  and the reinforcing bottom plate  54  are tack welded into place. These two parts use identical robot gripper locator holes. The lower leg  70 A also has the locating tabs for holding the attachment flange assembly  88  into position for tack welding in place. Likewise, the tabs  20 A,  20 B and  20 C are used for locating the bracket subassembly  22 . 
     The end plates are welded into position and the bucket is fully assembled except for the steps  98  which are also added at the end. 
     The formed top rail  24  and locating tabs  20 A,  20 B and  20 C are key to automated manufacture by providing positively located accessible weld junctions for robot welding. 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.