Abstract:
In the design of load bearing members for use in work machines, it is oftentimes beneficial to minimize the weight of such structures which, in turn, may allow for increased payloads and decreased cycle times of the work machine. However, such lightweight structures may require additional support in specific areas to withstand an anticipated loading condition. The present invention provides a load bearing arrangement for use with a work machine of the type having a platform. At least one member is coupled to the platform and has a longitudinal axis, and at least one reinforcing structure is attached to the member at at least one identified failure-prone location.

Description:
TECHNICAL FIELD  
         [0001]    This invention relates to an apparatus for reinforcing a load bearing member and, more specifically, to such an apparatus and method thereof in which at least one failure-prone location on the load bearing member is identified and reinforced.  
         BACKGROUND  
         [0002]    Load bearing members such as booms, sticks, crane booms and so forth typically must support loads which may produce a resultant load acting transversely across the member. Improvements in manufacturing processes such as welding processes allow for an improvement in the ability of the member to withstand loads. An example of such improvements would be an improvement in the quality of welds which decrease the extent of heat affected zones produced by the welding process. These improvements in the manufacturing processes, in turn, allow for use of thinner materials in creating these members resulting in possibly increased payloads and improved cycle times due to the decrease in weight of such structures. However, a point may be reached where the thickness of the member may be insufficient in a certain location or locations to support a desired loading condition. In such cases, it may be desirous to bolster these specific areas so as to allow the member to withstand the needed loading condition without sacrificing the minimization in the reduction in the weight of such members.  
           [0003]    Examples exist in the prior art which teach methods of reinforcing crane booms. Such examples can be found in, for example, U.S. Pat. No. 4,112,649 which issued on Sep. 12, 1978 to Fritsch et al., U.S. Pat. No. 4,027,448 which issued on Jun. 7, 1977 to Tymciurak, and U.S. Pat. No. 3,890,757 which issued on Jun. 24, 1975 to Lamet et al. all of which teach truss-type support methods for providing additional reinforcement to a crane boom.  
         SUMMARY OF THE INVENTION  
         [0004]    In accordance with an embodiment of the present invention a load bearing arrangement for use with a work machine of the type having a platform is provided where such an arrangement comprises at least on member coupled to the platform and having a longitudinal axis, and at least one reinforcing structure attached to the member at at least one identified failure-prone location.  
           [0005]    In accordance with another aspect of the present invention, a method for reinforcing a load bearing member for use with a work machine is provided comprising the steps of simulating a loading condition on the member, determining at least one location where the member is prone to buckling based on the simulation step, and proving the member with at least one reinforcing structure at that location. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1 is a side elevation view of an exemplary work machine embodying the principles of the present invention.  
         [0007]    [0007]FIG. 2 is an isometric view of a member comprising a boom embodying the principals of the present invention.  
         [0008]    [0008]FIG. 3 is an isometric view of a member comprising a stick embodying the principals of the present invention.  
         [0009]    [0009]FIG. 4 is a cross-sectional view taken through section  4 - 4  in FIG. 2.  
         [0010]    [0010]FIG. 5 is partial side view of the boom shown in FIG. 2.  
         [0011]    [0011]FIG. 6 is an isometric view of a member comprising a boom showing exemplary results of a buckling analysis.  
     
    
     DETAILED DESCRIPTION  
       [0012]    With reference now to the Figures, shown in FIG. 1 is an exemplary work machine  100  incorporating the teachings of the present invention. The work machine  100  comprises a platform  101  onto which is mounted a plurality of load bearing members  105  embodied herein by a first member or boom  106  and a second member or stick  107 . The boom  106  is pivotally connected to the platform  101  and moveable relative thereto by a first movement means embodied herein by a pair of first hydraulic actuators  110  which may comprise an extensible and retractable hydraulic cylinders. Likewise, the first end  111  of the stick  107  is pivotally coupled to the boom  106  via a suitable connector such as a pin  112  and is moveable relative to the boom  106  by a second movement means embodied herein by a second hydraulic actuator  114  which also may comprise an extensible and retractable hydraulic cylinder. It is to be understood that the work machine  100  shown herein is embodied by a barge unloader, however such a showing is exemplary only and it is contemplated that the teachings of the present invention may have wide applicability for work machines used to support loads such as, for example, backhoe loaders, excavators and so forth.  
         [0013]    Attached adjacent the second end  115  of stick  107 , also by use of a suitable connector such as a pin  118  , is an attachment  119  for use in grasping and holding a load of material which may comprise debris, dirt, rock, goods or other material types. The attachment  119  shown herein is embodied herein by a clamshell bucket although it is contemplated that such a showing is for purposes of illustration and not limitation and that other attachment types may also be used without deviating from the spirit of the present invention. The attachment  119  may also include a third hydraulic actuator (not shown) for use in activating the attachment  119 .  
         [0014]    With reference now to FIGS.  2 , the boom  106  is shown incorporating the teachings of the present invention. The boom  106  comprises a pair of spaced apart side plates  200  each attached preferably by a robotic welding process to a top plate  201  and a bottom plate  202 . The boom  106  includes a first end  205  comprising a pair of ears  206  wherein each ear  206  includes an aperture  209  for receipt of a pin (not shown) or other suitable device for pivotally coupling the boom  106  to the platform  101 . The boom  106  also includes a second end  210  also having a pair of ears  213  each having an aperture  214  for receipt of pin  118 . A tube  217  extends from each side plate  200  and is used to couple the first hydraulic actuators  110  to the boom  106 . Coupling assembly  218  extend from the bottom plate  202  and are used to pivotably support the second hydraulic actuator  114  in a well known manner.  
         [0015]    Also shown in hidden detail in FIG. 2 is a reinforcing structure  221  used to reinforce each of the side plates  200  against failure. Although the specific details of the reinforcing structure  221  will be explained in greater detail as this disclosure progresses, suffice to say for now the use of the reinforcing structures  221  of the present invention allows for the use of thinner side plates  200  while preventing buckling of the side plates  200  when load placed on the boom  106  reaches or exceeds a given amount.  
         [0016]    With reference now to FIGS.  3 , the stick  107  is shown also incorporating the teachings of the present invention. The stick  107  also comprises a pair of spaced apart side plates  300  each attached, also preferably by a robotic welding process, to a top plate  301  and a bottom plate  302 . The stick  107  includes the first end  111  sized to fit between the ears  213  of the second end  210  of the boom  106 . The first end  111  further includes an aperture  306  for receipt of pin  111  thereby providing for the aforementioned pivotal attachment to the boom  106 . The second end  115  of the stick  107  also includes an aperture  307  sized to receive pin  118 . Coupling assembly  309  extend from the bottom plate  302  and is used to pivotably support the second hydraulic actuator  114  in a well known manner.  
         [0017]    Also shown in hidden detail in FIG. 3 are a plurality of reinforcing structures each denoted by the reference numeral  310  which are used to reinforce each of the side plates  300  against buckling at pre-determined buckling prone areas. Although the specific details of the reinforcing structures  310  will also be explained in greater detail as this disclosure progresses, suffice to say for now the use of the reinforcing structures  310  of the present invention also allows for the use of thinner side plates  300  on the stick  107  while preventing buckling of the side plates  300  at pre-determined buckling prone areas when loads placed on the stick  107  reach or exceed a given amount.  
         [0018]    With reference to the discussion accompanying FIG. 6 below, it should be appreciated by those of ordinary skill in such art, that the number of reinforcing structures  221 , 310  to be used is a matter of design selection and need not constitute any more than is necessary to achieve the needed performance, and by limiting the number of reinforcing structures  221 , 310  used the weight of the boom  106  and the stick  107  may be minimized.  
         [0019]    With reference to the cross-sectional shown in FIG. 4, the location and configuration of the reinforcing structures  221 , 310  will now be discussed. For purposes of brevity the following discussion will be limited to the reinforcing structure  221  for the boom  106 , however it is to be understood that the disclosure herein is equally applicable to the reinforcing structures  310  used for the stick  107 . As shown, at least one reinforcing structure  221  is attached to an inner surfaces  400  of the side plates  200  by a suitable attachment method preferably a laser welding method. As should be appreciated by those of ordinary skill in such art, it has been found that the use of laser welding to attach the reinforcing structure  221  to the side plates  200  reduces the heat effected zone surrounding the weld area, thereby allowing for thinner side plates  200  then would otherwise be required for different welding-type attachment methods. It is to be understood that the attachment location of each reinforcing structure  221  is exemplary only and it is contemplated that other attachment locations for the reinforcing structures  221  may be had such as, for example, the outer surface  401  of each of the side plates  200 .  
         [0020]    As shown, each reinforcing structure  221  comprises a substantially straight member having a base portion  404  and a rib portion  405  extending from the base portion  404 . The reinforcing structure  221  may comprise a metallic or other rigid material and has a length which is user-selected based on the failure analysis performed on at least one of the members  105  and to be discussed with reference to FIG. 6. Furthermore, it is also contemplated that other geometry&#39;s for the reinforcing structure  221  may also be used with deviating from the spirit of the present invention such as, for example, a cylindrical or flat configuration.  
         [0021]    With reference now FIG. 5, a partial elevational view of the stick  107  is shown. Again, for the purpose of brevity, the following discussion will be in reference to the stick  107  but it is to be understood that the description provided herein applied equally as well to the boom  106 . The reinforcing structure  310  is shown in hidden detail attached to the side plate  300  in an exemplary orientation β relative to the boom longitudinal axis  500 . As should be appreciated by those of ordinary skill in such art, each reinforcing structure  310  may be attached to the side plate  300  at a user-selected orientations or angles β relative the boom&#39;s longitudinal axis  500  which can vary between zero (0) degrees and ninety (90) degrees.  
         [0022]    Shown in FIG. 6 is an exemplary diagram of the results of a buckling analysis performed on, for example, the boom  106 . As shown, the area denoted  600  protruding from the side plate  200  represents the location of the side plate  200  which is prone to buckling as based on a simulated load placed on the boom  106 . Although a variety of methods can be used to provide the aforementioned analysis, software programs such as, for example, Nastran (TM) can be used in conjunction with a computing system (not shown) to model loading characteristics on the boom  106  and stick  107  and obtain the aforementioned information related to buckling prone areas. Based on the information obtained from the aforementioned buckling analysis, the overall length of each reinforcing structure  221 ,  310  as well as size of the respective base and rib portions  404 ,  405  may be chosen without undue experimentation.  
         [0023]    Industrial Applicability  
         [0024]    In use and in operation, each reinforcing structure  221 , 310  may be located on the boom  106 , the stick  107 , or both so as to bolster those identified failure-prone areas  600  which may be prone to buckling when subject to loads meeting or exceeding a certain level. As should be appreciated by those of ordinary skill in such art, by locating the reinforcing structures  310  in only those areas which require the needed support, the weight of the boom  106  and stick  107  may be kept to a minimum, thereby providing for increased payloads and reduced cycle times for a any given job. Modeling programs such as Nastram (TM) which are typically used with computing systems may be used to identify potential areas of the boom  106  and stick  107  which may be subject to failure. As should be appreciated by those of ordinary skill in such art, by identifying failure prone locations of the boom  106  and stick  107 , the size and location of each reinforcing structure  221 , 310  may be optimized so as to minimize the weight of the boom  106  and stick  107 ; thereby increasing the potential payload of the work machine  100 .  
         [0025]    Other aspects, objects and advantages of this invention can be obtained from a study of the drawings, the disclosure and the appended claims.