Abstract:
A tube over tube joint for an implement frame includes a self-fixturing weldable connector positioned between upper and lower tubes. Standard fillet welds connect the tubes to the connector. A unitary casting can be used made from material selected to optimize load transfer between the top and bottom tubes to improve the fatigue life of the joint. The casting is self-fixturing so the top tubes can be located by simply placing in the casting on the lower tubes. A tube end connector provides fixturing and weld surfaces for butt joints in planar frames. Outwardly extended weld edges on the connector increase resistance to parallelogramming.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to agricultural implement frames and, more specifically to tube joints for such frames.  
       BACKGROUND OF THE INVENTION  
       [0002]     Many agricultural implement frames include tubular members welded or connected together by brackets. The joints are subjected to very high loads and stresses.  
         [0003]     Tube over tube connections for an implement frame construction typically employ one of two methods of construction. The first method includes welding the top and bottom tubes directly together using flare bevel welds. The direct weld procedure requires joint welds in hard to reach positions. If welds are required around tube corners, robotic welding techniques often are not used since programming the robot to closely follow the corners is not always possible. Fatigue and less than optimum load transfer characteristics of some joints can result in a weakened frame. The second method of frame construction uses gusset plates vertically extending between the top and bottom tubes and welded to the tubes. The weld positioning is better using the gusset method than the direct tube to tube weld method, but gusset weld methods often result in a joint with a lower fatigue life compared to other types of joints.  
         [0004]     A further method involves tube through tube construction such as shown and described in commonly assigned U.S. Pat. No. 6,016,877. Such construction provides excellent frame tube joints and a very strong overall frame without need for extensive fixturing during manufacture, but such joints require laser cut apertures through tubes and are relatively expensive to produce. In addition, welding tube ends to adjoining tubes in the same plane continues to be a source of difficulty.  
       SUMMARY OF THE INVENTION  
       [0005]     It is therefore an object of the invention to provide an improved frame joint for an agricultural implement frame. It is another object to provide such a joint that overcomes most or all of the aforementioned problems.  
         [0006]     It is a further object of the invention to provide an improved welded frame joint for an implement which is stronger, subject to less fatigue, and easier to manufacture than at least most previously available implement frame joints. It is another object to provide such a joint which is self-fixturing and is easily weldable using standard fillet welds at conveniently accessed locations.  
         [0007]     Tube over tube implement frame joints include self-fixturing weldable castings positioned between upper and lower tubes. Standard fillet welds connect the tubes to the casting at conveniently accessible locations. The material in the casting is selected to optimize load transfer between the top and bottom tubes to improve the fatigue life of the joint. The weldable casting can be placed at any required joint area and provides an easy weld joint for both human and robotic welders. Since the casting is self fixturing, the top tubes can be located by simply placing in the casting without need for costly fixtures. In another embodiment of the invention, castings are provided at the ends of tubes to facilitate butt joint fixturing and welding for connecting tubes lying in the same plane. The above-described connections spread the weld locations for increased resistance to parallelogramming and better load balancing at the joints. The connections also provide added strength and fatigue resistance at tube joints adjacent hinge locations.  
         [0008]     These and other objects, features and advantages of the present invention will become apparent from the description below taken in view of the drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a perspective view of a portion of an agricultural implement frame.  
         [0010]      FIG. 2  is an enlarged perspective view of a frame joint for the frame of  FIG. 1 .  
         [0011]      FIG. 3  is a perspective view of a connector utilized with the frame joint of  FIG. 2 .  
         [0012]      FIG. 4  is a perspective view of another embodiment of a connector utilized for a tube over tube construction.  
         [0013]      FIG. 5  is a perspective view of the connector of  FIG. 4  welded to frame tube.  
         [0014]      FIG. 6  is a perspective view of a frame butt joint for connecting a tube end to an adjoining tube in generally the same plane. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]     Referring to  FIG. 1 , therein is shown an implement frame  10  having transversely extending tubular beam or frame tubes  12 ,  14  and  16  connected to fore-and-aft extending tubular beam or frame tubes  18 ,  20 ,  22 ,  24  and  26 . The beams are rectangular in cross-section with rounded corners, and a beam over beam construction is utilized to connect the tubes  12 ,  14  and  16  to the beams  20 ,  22 ,  24  and  26  to provide a main frame of generally rectangular configuration. The right ends (as viewed in  FIG. 1 ) of the beams  12 - 16  are connected to the inside face of the fore-and-aft beam  18 . For purposes of the description, the beams  20 - 26  are designated as lower or first beams and the beams  12 - 16  are designated as upper or second beams, but it is to be understood that the positions can be reversed or otherwise changed and that the upper and lower designations are for providing a reference for clarity in the description of the drawings. Earthworking or seeding tools and hitch structure (not shown) for towing the frame forwardly (F) through a field with the tools engaging the soil. The heavy loads encountered by the implement frame  10  during transport and field-working operations require strong connections at the beam joints.  
         [0016]     To provide self-fixturing and a strong, permanent connection between the upper and lower beams, a weldable connector or casting  30  is positioned at joint locations. The casting  30  as shown in  FIGS. 2 and 3  includes an upwardly directed channel or saddle portion  32  ( FIG. 3 ) and a downwardly opening channel or saddle portion  34 . For a right-angle joint as shown in the figures, the saddle portion  32  includes a channel  32   c  conforming generally to the shape of the upper beam  16  ( FIG. 2 ) and a channel  34   c  conforming generally to the shape of the lower beam  20  and perpendicular to the channel  32   c.  The connector  30  can be fixed to one of the beams and functions as a fixture to locate the other of the beams. The channel configurations thus provide easy and reliable set up of the frame components without need for additional fixturing.  
         [0017]     As best seen in  FIGS. 2 and 3 , the connector  30  includes opposite pairs of bifurcated flanged or leg portions  40  having generally planar inside surfaces  44  defining the channel  34   c.  Slots  46  with arc-shaped top portions  48  separate the leg portions  40 , and tapered flanges  50  project outwardly from the channel  34   c.  The leg portions  40  extend upwardly to a connection with bottom  32   b  ( FIG. 3 ) of the saddle portion  32 . The bottom  32   b  is generally open between the opposite leg portions  40 .  
         [0018]     Planar channel walls  52  extend upwardly from the bottom  32   b  to define the channel portion  32   c.  The walls  52  include uppermost edges  56  having a height approximately half the dimension of the corresponding wall of the beam  16 . A notch  58  is centrally located in each uppermost edge and provides a paint drainage channel. The connector  30  is fixed to the upper beam  16  by welds at locations  60  between the corners of the beam. The welds  60  are offset from the corners for easy access, to reduce or eliminate the welds at the beam corners, and to provide better load and stress distribution at the joints. The leg portions  40  are welded to the corresponding walls of the beam  20  at locations  62  also offset from the beam corners.  
         [0019]     In an alternate embodiment ( FIGS. 4 and 5 ), a connector  70  includes opposite leg portions  80  which are generally planar and define the channel  34   c  of saddle portion  34 ′. The leg portions  80  extend upwardly to a connection with bottom  82   b  of saddle portion  32 ′. The bottom  82   b  is open between the leg portions  80  and connects to planar channel side walls  92  having top edges  96  with a central raised edge portion  98 . A side extension  100  is located outwardly of each of the side walls  92  and provides a conveniently located edge for connecting the extension to the top surface of the tube  20  ( FIG. 5 ) at weld location  102 . The opposite edges of the leg portions  80  are welded at  104  to the side walls of the tube  20 . The welds  104  are offset from the tube corners. The edges  96  are welded at locations  106  to the upright side walls of the tube  16 . The extension  100  provides a central weld location relative to the adjoining beam  20  and provides good distribution of stress at the joint. By spreading out the weld locations with the connectors as shown, resistance to - parallelogramming is increased and stresses on the tubes are reduced. The joint is thus strengthened, and problems of in-plane shearing caused by frame parallelogramming are reduced or eliminated. The raised portion  98  does not require welding and provides a locator for the innermost portions the welds  106 .  
         [0020]     To provide butt joints for a planar configuration ( FIG. 6 ), a weldable connector  132  includes a saddle portion  132  opening towards a first beam or tube  20 ′. The saddle portion  132  includes leg portions  140  similar in construction to the leg portions  40  described above for  FIGS. 2 and 3  and defining a channel  134   c  for receipt on the tube  20 ′. A saddle portion  144  conforms to the cut end of a second tube  16 ′ and includes planar channel walls  162  with curved edges  170  which are welded at locations  172  to opposite walls of the tube  16 ′. The welds at  172  are offset inwardly from the corners of the tube  16 ′. Welds  174  connect the leg portions  140  to the walls of the tube  20 ′ inwardly of the adjacent corners of the tube. A hinge receiving end of the tube  20 ′ can receive hinge structure (not shown) for connecting one section of the implement frame to an adjoining section adjacent the connector  132 . The above-described joint provides a strong and fatigue-resistant connection at the hinge area.  
         [0021]     Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.  
       Assignment  
       [0022]     The entire right, title and interest in and to this application and all subject matter disclosed and/or claimed therein, including any and all divisions, continuations, reissues, etc., thereof are, effective as of the date of execution of this application, assigned, transferred, sold and set over by the applicant(s) named herein to Deere &amp; Company, a Delaware corporation having offices at Moline, Ill. 61265, U.S.A., together with all rights to file, and to claim priorities in connection with, corresponding patent applications in any and all foreign countries in the name of Deere &amp; Company or otherwise.