Abstract:
Disclosed is a two station positioner for positioning work pieces for mounting and working at the same time. A first arm positioner can be located in a mounting position for mounting a work piece on the first arm positioner, while the other arm positioner is located in a working position, where another work piece can be welded or machined. The first positioning arm, in the mounting position, is sufficiently low to allow workers to mount the work piece without the use of elevated platforms. A pedestal exchange platform can then be indexed to place the first positioning arm with the mounted piece in the working position and the other positioning arm in the mounting position. In this manner, workers can mount work pieces while other work pieces are being worked. In the working position, the positioning arm is rotated on a horizontal axis, which reduces programming complexity for robotic welders or machines.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based upon and claims priority to U.S. provisional application Ser. No. 61/671,002, filed Jul. 12, 2012, entitled “Offset Index Welding Positioner,” which application is specifically incorporated herein by reference for all that it discloses and teaches. 
     
    
     BACKGROUND 
       [0002]    Automated welding techniques using robotic welders and large positioners have greatly increased the quality of industrial welding. Greater reliability can be provided using automated welding techniques. In addition, the welds can be completed rapidly, without the use of highly paid and highly skilled welders. 
         [0003]    In addition, the use of positioners to position a piece for welding has also provided for high quality welds. Welds that are performed when the weld is disposed in a horizontal position allow the weld to properly flow into an opening and properly fill the space in the opening. Large positioners are capable of rotating large pieces into positions, so that horizontal, high quality welds can be performed. 
       SUMMARY 
       [0004]    An embodiment of the present invention may therefore comprise a two station positioner for positioning work pieces for mounting and working comprising: a pedestal exchange platform having a pedestal mounting surface, a first arm mounting surface that is disposed at a first angle to the pedestal mounting surface, and a second arm mounting surface that is disposed at a second angle to the pedestal mounting surface, the second angle being substantially equal and opposite to the first angle; a first positioning arm assembly disposed on the first mounting surface; a second positioning arm assembly mounted on the second mounting surface; a pedestal having a floor mounting surface that is adapted to mount the pedestal on a floor, and a slanted surface that is slanted at a third angle from the floor mounting surface, the third angle having a magnitude that is equal the first angle and the second angle; a pedestal indexer that rotates the pedestal exchange platform to a first position in which the first positioning arm is in an elevated working position that allows a first work piece mounted on the first positioning arm to be at least partially rotated and worked, the first positioning arm having a first arm pivot for rotating the first positioning arm, the first arm pivot having a first axis that is substantially parallel to the floor mounting surface, and the second positioning arm is in a mounting position which allows workers to mount a second work piece to the second positioning arm at standing height without the use of elevated platforms, and that rotates the pedestal exchange platform to a second position in which the second positioning arm is in the elevated working position, the second positioning arm having a second arm pivot for rotating the second positioning arm, the second arm pivot having a second axis that is substantially parallel to the floor mounting surface, and the first positioning arm is in a mounting position which allows workers to remove the first work piece and mount a third work piece to the first positioning arm at standing height without the use of elevated platforms. 
         [0005]    An embodiment of the present invention may further comprise a method of positioning work pieces on a two station positioner for mounting and working comprising: mounting a pedestal exchange platform on a slanted surface of a pedestal, the slanted surface disposed at a third angel to a pedestal mounting surface of the pedestal; placing a first positioning arm on a first arm mounting surface of the pedestal exchange platform, the first arm mounting surface disposed at a first angle to the slanted surface so that the first positioning arm rotates on an axis that is substantially parallel to the pedestal mounting surface when the first positioning arm is in a working position, and tilts the first positioning arm to a mounting height that allows mounting and removal of a work piece at a standing height without the use of elevated platforms when the first positioning arm is in a mounting position; placing a second positioning arm on a second mounting surface of the pedestal exchange platform, the second arm mounting surface disposed at a second angle to the slanted surface that is substantially equal and opposite to the first angle, so that the second positioning arm rotates in an axis that is substantially parallel to the pedestal mounting surface when the second positioning arm is in a working position, and tilts the second positioning arm to a mounting height that allows mounting and removal of a work piece at a standing height without the use of elevated platforms when the second mounting arm is in a mounting position; indexing the first positioning arm and the second positioning arm alternately between the working position and the mounting position so that workers can mount a work piece while another work piece is being worked. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is an isometric view of an embodiment of an offset welding positioner. 
           [0007]      FIG. 2  is a left side view of the embodiment of  FIG. 1 . 
           [0008]      FIG. 3  is a top view of the embodiment of  FIG. 1 . 
           [0009]      FIG. 4  is a front view of the embodiment of  FIG. 1 . 
           [0010]      FIG. 5  is another perspective view of the embodiment of  FIG. 1 . 
           [0011]      FIG. 6  is another perspective view of the embodiment of  FIG. 1  with an arm in the vertical position. 
           [0012]      FIG. 7  is a left side view of the embodiment of  FIG. 1  with an arm in a vertical position. 
           [0013]      FIG. 8  is a left side view of the embodiment of  FIG. 1  with the pedestal pivot rotates by 90 degrees. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0014]      FIG. 1  is an isometric view of an embodiment of an offset welding positioner  100 . As illustrated in  FIG. 1 , the offset welding positioner  100  includes a pedestal  102 , having a pedestal indexer  112 . The top portion of the pedestal  102  is slanted by a predetermined angle to provide a slanted surface  146  ( FIG. 2 ). In this case, the angle is approximately 20 degrees from horizontal. Other angles can be used to provide a greater or less offset, as explained in more detail below. There are two positioning arm assemblies comprising positioning arm  104  and arm pivot  110  ( FIG. 2 ), and positioning arm  106  and arm pivot  128  ( FIG. 2 ) that are attached to the pedestal indexer  112  at the top of the pedestal  102  on the slanted surface  146 . Positioning arm  104  is mounted on an arm pivot  110  that allows the positioning arm  104  to rotate around the arm pivot  110 . A similar arm pivot  114  is coupled to the positioning arm  106 , as illustrated in  FIG. 2 . A welding shield  108  is disposed between positioning arm  104  and positioning arm  106  to prevent weld spatters from being transmitted from work pieces disposed on a positioning arm in working position  103 . The work piece (not shown) is mounted on head stock platter  118  and tail stock platter  120  of positioning arm  104 . A turning unit  116  rotates the work piece on the stock platters  118 ,  120 . Tail stock platter  120  pivots on shaft  121 , which rotates on an axis aligned with the axis of the head stock platter  118 . 
         [0015]    Work pieces for welding and machining are typically lifted into position by a hoist or other device for attachment to stock platters, such as head stock platter  118  and tail stock platter  120 . These work pieces can be large and heavy objects that are difficult to position and move to the proper location for attachment to the platters. Additionally, in order to provide sufficient room to rotate the positioning arm, the positioning arm  104  must be located in an elevated working position, such as working position  103 , as shown in  FIG. 1 . In the elevated working position  103  of the positioning arm  104 , illustrated in  FIG. 1 , it is difficult to attach the work piece to the head stock platter  118  and tail stock platter  120 . Many times, the positioning arm  104 , in the horizontal position illustrated in  FIG. 1 , is substantially higher than a height at which a person can reach and attach the work piece. In most cases, the users must stand on ladders and raised platforms to attach and detach the work piece. OSHA regulations, in many cases, require that a platform to used rather than ladders. A movable platform for this purpose is expensive. Stairs must be provided on the platform as well as hand rails. In addition, if the platform is over 4 feet high, harnesses that are attached to the platform must be used. This results in an expensive and time consuming process. To solve these problems, the embodiment of  FIG. 1  includes a two station positioner  100  that has a working position  103  that is elevated for working and a mounting position  105  that is at a level that allows workers to mount work pieces, while standing on the floor. 
         [0016]      FIG. 2  is a left side view of the offset welding positioner  100  of  FIG. 1 . As illustrated in  FIG. 2 , the pedestal  102  has a slanted surface  146  to which the pedestal indexer  112  is attached. The pedestal indexer  112  functions to index (rotate) the pedestal exchange platform  124  so that the positioning arms  104 ,  106  can be rotated to opposite positions, i.e., a working position  103  and a mounting position  105 , and vice versa. In other words, for the configuration shown in  FIG. 2 , positioning arm  106  is located in the mounting position  105  for loading with a work piece (not shown) at a location that is close to the floor  134 . The head stock platter  132  is located at a height such that person can guide the work piece on a hoist or other device onto to the head stock platter  132  while standing on floor  134 . In this manner, expensive platforms, stairs, hand rails and harnesses are not needed to load the work piece onto the positioning arm  106 . The mounting of a work piece on the positioning arm  106  can occur while automated welding or machining is being performed on a different work piece (not shown) that is mounted on positioning arm  104 , which is in working position  103 . Positioning arm  104  is located above floor  134  by an amount that allows the positioning arm  104  to rotate on the arm pivot  110 . The work piece (not shown) on positioning arm  104  is mounted on the head stock platter  118  and can also rotate in an axis defined by shaft  121 . As disclosed below, the height of the positioning arm  104  is sufficient to provide clearance so that the positioning arm  104  can be completely rotated by the arm pivot  110  without interference with the floor  134 . Welding shield  108  provides protection for workers who are mounting a work piece on the head stock platter  132  while the welding functions are being performed on the work piece that is secured to the positioning arm  104 . 
         [0017]    An additional feature of the embodiment of welding positioner  100 , that is illustrated in  FIG. 2 , is the unique design of the pedestal exchange platform  124  and the angle of the mounting surfaces  126 ,  130  that result in the axis  138  of arm pivot  110  being horizontally disposed when the positioning arm  104  is in working position  103 , as shown in  FIG. 2 . The third angle  142  is the angle of the top of the pedestal  102  from horizontal, which is also approximately 20 degrees. Other angles, of course, can be used. The first angle  144  of the mounting surface  126  is the angle at which the mounting surface  126  is disposed relative to the slanted surface  146  of the pedestal  102 . Angles  142 ,  144  are substantially equal so that when the pedestal exchange platform  124  is rotated by the pedestal indexer  112  and pedestal indexer motor  122  to working position  103 , as shown in  FIG. 2 , the mounting surface  126  is substantially horizontal and parallel to floor (pedestal mounting surface)  134 . When the pedestal exchange platform  124  is indexed so that positioning arm  104  is located in the mounting position  105 , which is the position of positioning arm  106  in  FIG. 2 , angle  142  and  144  are added together to tilt the positioning arm  104  by twice the angle of the slanted surface  146 , such as illustrated in with respect to positioning arm  106  and angle  146 . In other words, angle  144  subtracts from angle  142  in working position  103 , so that the mounting surface  126  is substantially horizontal. When the positioning arm  104  is indexed by 180 degrees to the mounting position  105 , first angle  144  adds to the third angle  142 , as shown by positioning arm  106  in  FIG. 2 . 
         [0018]      FIG. 2  illustrates second angle  146 , which is the angle between the mounting surface  130  and the slanted surface  146 . Angle  150  is the total angle of tilt of the positioning arm  106  in the mounting position shown in  FIG. 2 . Angle  150  is equal to second angle  148  plus third angle  142  since these angles add together when the pedestal exchange platform  124  locates the positioning arm  106  in the mounting position, as shown in  FIG. 2 . Since second angle  148  is substantially equal to third angle  142 , angle  150  is substantially twice the magnitude of third angle  142 . The angle  150  allows the positioning arms  104 ,  106  to be located in a position that allows users to mount work pieces while standing on the floor  134  and raises the work pieces to a much higher level in working position  103 , which allows the positioning arms  104 ,  106  to rotate in 360 degrees without interfering with the surfaces of the floor  134 . Additionally, in working position  103 , the third angle  142  of the slanted surface  146  and the angles  144 ,  148  of mounting surfaces  126 ,  130 , respectively, position the axis  138  of arm pivot  110  and axis  140  of arm pivot  128  in a substantially horizontal position, or a position that is substantially parallel to the pedestal mounting surface, which is the floor  134 . An advantage of having the axes  138 ,  140  in a substantially horizontal or parallel position to the floor  134  is that a welding or machining device that is performing automated or robotic welding or machining is easier to program since there is no change in the lateral distance of various portions of a work piece from the robotic welder or robotic machining device as the positioning arms  104 ,  106  rotate on axes  138 ,  140 , respectively. For example, as positioning arm  104  rotates along the axis  138  in response to the arm pivot  110 , a work piece mounted on positioning arm  104  is located in a single, vertical plane or a plane that is substantially normal to the mounting surface or floor surface  134 . A robotic welder that is mounted on the floor surface can be much more easily programmed to locate positions for welding if the plane of rotation of the positioning arm  104  on axis  138  is vertical, or normal to the surface of the floor  134 . If the axis  138  is not substantially parallel to the floor  134  (horizontal), the plane of rotation of the positioning arm  104  will cause the lateral distance between the work piece and the robotic welder to vary as the positioning arm is rotated. This adds an additional degree of programming difficulty in programming a welder to make welds automatically on the work piece. 
         [0019]      FIG. 3  is another isometric view of the offset welding positioner  100  that corresponds to the embodiments of  FIGS. 1 and 2 . As illustrated in  FIG. 3 , the positioning arm  106  is positioned by arm pivot  114  in a horizontal position. Similarly, positioning arm  104  is positioned in a horizontal position on arm pivot  110 . Pedestal indexer  112  is located on the pedestal  102 . Pedestal indexer  112  cannot be activated by pedestal indexer motor  122  until both positioning arms  104 ,  106  are disposed in a horizontal position. Welding shield  108  protects a worker who may be mounting a work piece on the positioning arm  106  while welding is being performed by a robot on a work piece that is mounted on positioning arm  104  via head stock platter  132  and tail stock platter  136 . 
         [0020]      FIG. 4  is a front view of the offset welding positioner  100 . As illustrated in  FIG. 4 , the positioning arm  104  is in a horizontal position. The pedestal indexer motor  122  has rotated the pedestal exchange platform  124  so the positioning arm  104  is in working position  103 . Positioning arm  106  is in the mounting position. Pedestal  102  is bolted to the floor  134 . A work piece can be mounted on the head stock platter  132  and the tail stock platter  136  while the positioning arm  106  is in the mounting position  105 , as shown in  FIG. 4 . 
         [0021]      FIG. 5  is an isometric view that illustrates the offset welding positioner  100  with the positioning arm  104  in working position  103  and partially rotated. Positioning arm  104  rotates around the arm pivot  110  and is driven by arm pivot motor  206 . 
         [0022]      FIG. 6  is an isometric view of the offset welding positioner  100  with the positioning arm  104  rotated to a vertical position. As can be seen in  FIG. 6 , the positioning arm  104  is in working position  103  and has sufficient clearance to rotate an entire 360 degrees without interfering with the floor  134 . The positioning arm  104  rotates around the arm pivot  110 , which has a horizontal axis. In this manner, the plane of movement of the rotating positioning arm  104  is vertical. 
         [0023]      FIG. 7  is a left side view of the embodiment of the offset welding positioner  100  with the positioning arm  104  in a vertical position. Again, the positioning arm  104  has sufficient clearance to avoid interference with the floor  134  and, as such, can rotate an entire 360 degrees. At the same time, positioning arm  106  is in mounting position  105  at a height that allows users to mount work pieces to positioning arm  106  without the use of platforms or ladders. 
         [0024]      FIG. 8  is a left side view of the offset welding positioner  100  that corresponds to the left side view of  FIG. 2 , except that the pedestal exchange platform  124  has been indexed by 90 degrees. Positioning arm  106  is being indexed in a counter-clockwise direction viewed from the top from the mounting position  105  to the working position  103 . As shown in  FIG. 8 , the pedestal exchange platform  124  has been rotated or indexed by 90 degrees and will be indexed another 90 degrees until the positioning arm  106  is in the working position  103 . At the same time, positioning arm  104  (not shown) is being indexed from the working position  103  to the mounting position  105 . When positioning arm  106  is in the working position  103 , arm pivot  128  will be horizontal and parallel to the floor  134 . Positioning arm  104  will be in the mounting position  105 , so that a work piece that has been welded or machined can be removed by workers and replaced with a new work piece. 
         [0025]    Hence, the offset welding positioner  100  allows users to mount work pieces in a mounting position  105  at a height that does not require the use of expensive platforms with stairs, hand railings and harnesses. Further, the work pieces are indexed to a working position  103 , so that rotation of the positioning arm does not interfere with the floor and maintains a substantially lateral distance from a robotic welder as the positioning arm is rotated. As such, complex programming to program a robotic welder is not required. 
         [0026]    The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art.