Abstract:
A robot aligning apparatus includes a pointer which may be connected to either the robot or the tool carried by the robot. The apparatus also includes a stationary post having a sleeve mounted thereon. The robot or the tool with the pointer mounted thereon are moved to a test station adjacent the sleeve and post, and the sleeve is moved upwardly over the pointer to indicate proper alignment.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a robot alignment apparatus and method for using same. 
     During the use of robotic equipment, occasionally the equipment becomes misaligned. The misalignment may occur because of a programming error or it may occur because of an unplanned collision of the robotic equipment with the work piece. 
     In such situations it is necessary to check the alignment of the robot and the alignment of the tool that is mounted to the robot. Previous alignment tools included such things as dial indicators, sharp pointer levels, and scribe marks on the tools. Typically such methods required expensive tools and complicated procedures to check the alignment of both the robot and the tool with respect to the position of the work piece. 
     It is necessary to check both the alignment of the tool and the alignment of the robot because these two objects can be misaligned individually. For example, a collision might cause misalignment of the tool even though the robot remains in its originally programmed aligned position. Alternatively the tool may be properly aligned, but the program for the robot may cause it to be misaligned. Checking both of these alignments enables the operator to properly align the robot and the tool for use in operating on the work piece. 
     Therefore a primary object of the present invention is the provision of an improved robot alignment apparatus and method for using same. 
     A further object of the present invention is the provision of an improved robot alignment apparatus which can be used for checking both the alignment of the robot and the alignment of the tool held by the robot. 
     A further objective is the provisions of a robot alignment apparatus and method which utilize the same alignment equipment for aligning both the robot and the tool being carried by the robot. 
     A further object of the present invention is the provision of a robot alignment apparatus which can be quickly and easily mounted on the robot or on the tool for use in aligning the tool and the robot. 
     A further object of the present invention is the provision of an improved robot alignment apparatus which is simple in construction, economical in manufacture, and easy to use. 
     SUMMARY OF THE INVENTION 
     The foregoing objects may be achieved by a robot alignment apparatus having a stationary alignment tool mounted in a predetermined stationary position at an alignment station. The alignment tool comprises a fixed member and a movable member. The movable member is mounted for movement relative to the fixed member along a straight-line alignment axis from a first position to a second position. 
     The robot includes a robot member, and the robot is programmed to move the robot member to an alignment position adjacent the alignment station. An alignment pointer is detachably connected to the robot member for movement with the robot member to the alignment station. 
     The movable member maintains a fixed clearance distance from the alignment pointer during movement of the movable member from its first position to its second position to indicate desirable alignment of the robot in the alignment position. 
     The movable member moves a variable distance from the alignment pointer during movement of the movable member from its first to second positions to indicate an undesirable alignment of the robot in the alignment position. 
     According to one feature of the invention the robot alignment apparatus includes an elongated bore and the pointer protrudes within the elongated bore when the movable member is in its second position. 
     According to another feature of the invention the pointer includes a longitudinal axis and a side surface surrounding and facing away from the longitudinal axis. The fixed clearance distance comprises the distance between the side surfaces of the pointer and the bore walls of the bore. 
     According to a further feature of the invention the side surface of the pointer includes first and second flanges spaced apart from one another along the longitudinal axis of the pointer. The first and second flanges have outer flanges surfaces which conform in shape to the cross sectional shape of the bore. 
     According to another feature of the invention the first and second flanges remain at a fixed distance from the side walls of the bore during movement of the movable member from its first position to its second position to indicate proper alignment of the robot in the alignment position. 
     According to another feature of the invention the first and second flanges will move to variable distances from the side wall of the bore during movement of the movable member from its first to its second position to indicate improper alignment of the robot when in its alignment position. 
     According to another feature of the invention the bore is circular in cross section and the first and second flanges are circular in cross section. 
     According to a further feature of the present invention the robot member comprises a part of the robot. 
     According to another feature of the invention the robot member comprises a tool attached to the robot. 
     The method of the present invention comprises attaching a pointer to the movable robot member on a robot. The next step comprises moving the robot member and the pointer to a test position adjacent the test station. The method next comprises moving a movable alignment tool positioned at the test station along a straight line axis from a first position to a second position whereby the distance between the movable alignment tool and the pointer remains constant throughout movement of the alignment tool between its first and second positions whenever the robot is properly aligned, and varies whenever the robot is improperly aligned. 
     According to another feature of the method of the present invention the pointer axis and the straight line axis extend in the same direction whenever the pointer is in its test position and the robot is properly aligned, and they extend at angles with respect to one another whenever the robot is improperly aligned. 
     According to another feature of the method of the present invention the pointer axis and the straight-line axis are colinear when the robot is properly aligned. 
     According to another feature of the method of the present invention the alignment tool includes a tool bore and the method further comprises moving the movable tool into surrounding relation with respect to the pointer whereby the pointer is within the bore when the movable tool is in its second position. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWINGS 
     FIG. 1 is an elevational view of a typical robot having a welding torch mounted thereon and showing the pointer of the present invention mounted on both the robot and the torch. 
     FIG. 1A is an enlarged sectional view taken along line  1 A— 1 A of FIG.  1 . 
     FIG. 2 is a sectional view taken along line  2 — 2  of FIG.  1 . 
     FIG. 3 is a view similar to FIG. 2, but showing the alignment sleeve in its upper position. 
     FIG. 4 is an enlarged sectional view taken along line  4 — 4  of FIG.  1 . 
     FIG. 5 is a view similar to FIG. 4, but showing the alignment sleeve in its upper position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, the numeral  10  generally designates a typical robot. Robot  10  includes a support mast  12 , an upper arm  14 , a middle arm member  16 , and a lower arm member  18 . Upper arm member  14  and middle arm member  16  are pivotally mounted for pivotal movement about an upper pivot axis  20 . Middle arm member  16  and lower arm member  18  are pivotally mounted about an elbow axis  22 . Lower arm member  18  is pivotally mounted to an adapter plate  46  for pivotal movement about a wrist pivot axis  24 . Mounted to the adapter plate  46  is a collision sensor  26  which is adapted to sense when the robot collides improperly with a foreign object. The collision sensor then disables the robot so that proper alignment can be recalibrated. 
     Upper arm  14  and support mast  12  are joined at a shoulder joint  28  which has the capability of pivoting about a horizontal axis  30  and a vertical axis  32 . 
     Mounted on the robot  10  is a welding torch console  34  which is held in place by a bracket  36 . Extending from console  34  is a hose  38  having a welding torch  40  on its outer end. Welding torch  40  is attached to the collision sensor  26  by means of a torch bracket  42 . 
     Mounted on the end of torch  40  is an alignment pointer  44 . In order to mount the alignment pointer  44  on the torch  40  it is first necessary to remove the nozzle (not shown) and the contact tip (not shown) from the end of the torch  40 . 
     A similar pointer  44  is also mounted on the adapter plate  46 . In FIG. 1 for illustrative purposes the pointer  44  is shown mounted both to the adapter plate  46  and the nozzle  40 . However, in normal application it is necessary only to use one pointer  44  and to separately mount that pointer  44  on the adapter plate  46  or the torch  40 . 
     Referring to FIG. 1A, adapter plate  46  includes a threaded bore  48  which extends into a beveled edge  50  as shown in FIG.  1 A. 
     The pointer  44  has a circular cylindrical shape, but the cross sectional shape of the pointer  44  could be square or of almost any configuration without detracting from the invention. The pointer  44  includes an upper pointer flange  52 , a lower pointer flange  54  and a reduced central diameter surface  56 . 
     As seen in FIG. 1A, the bottom of pointer  44  is provided with a large counter bore  58  and the upper portion of the pointer  44  is provided with a smaller threaded bore  60 . The pointer  44  includes a flat upper surface  62  and a similar flat end  63  at the opposite end. 
     A threaded stud  64  includes a small threaded end  66  and a larger threaded shank  68 . Stud  64  is threaded upwardly into threaded bore  60  and also is threaded within the threaded bore  48  of adapter plate  46 . This causes the upper flat surface  62  to abut against the beveled edge  50  of adapter plate  46  and securely holds the pointer  44  in rigid connection to the adapter plate  46 . 
     FIGS. 2 and 3 illustrate the manner in which the robot is aligned. The robot is programmed to move to a test station designated generally by the numeral  78  as shown in FIG.  2 . At the test station  78  is an alignment tool  80  which comprises a sleeve  82  and a post  84 . The sleeve  82  includes a sleeve bore  86 , and is mounted over the post  84  so that it can slide vertically from the position shown in FIG. 2 to the position shown in FIG.  3 . The inner diameter of sleeve bore  86  conforms to the shapes and sizes of flanges  52 ,  54  on pointer  44 , but is slightly larger so as to permit the sleeve to slide with close tolerance over the flanges  52 ,  54  as shown in FIG.  3 . In the preferred embodiment the pointer  44  is circular in cross section, but as previously explained, the cross sectional configuration could be changed without detracting from the invention. However, the cross sectional configuration of the flanges  52 ,  54  should be the same as the cross sectional configuration of the sleeve  80  so that there is a close tolerance between the flanges  52 ,  54  and the inner walls of bore  86 . 
     If the robot is properly aligned the sleeve  82  will slide easily upwardly over both of the flanges  54 ,  52 . However, if it slides only over flanges  54  but will not slide over flanges  52  that is an indication that the robot is misaligned and it will need to be reprogrammed. The advantage of using spaced apart flanges  52 ,  54  is that misalignment can be more easily discerned. If the pointer  44  were of uniform cross section along its entire length, the sleeve would bind during misalignment and it would not be as easy to determine whether or not or how much the alignment is off. However, with the spaced apart flanges  52 ,  54  the sleeve easily slips over the lower flanges  52 , but is only properly aligned if it will slip over the upper flanges  52 . 
     Post  84  is mounted by means of a bolt  88  to an L-shaped frame  90  having an upstanding leg  92  and a lower horizontal leg  94 . The L-shaped frame  90  is mounted in a stationary position at test station  78 . The test station  78  may be chosen at any location within the reach of robot  10 , and the robot  10  is programmed to move to the test station for testing for proper alignment. At the upper end of upstanding leg  92  is a positioning bolt  96  which is adapted to fit against a flat edge  98  of adapter plate  46 . This is important so as to insure that the adapter plate  46  is rotated to the proper rotational position about wrist pivot axis  24 . If the adapter plate  46  is not rotated to the proper position the pointer will misalign with the sleeve  80 . Bolt  96  provides a means whereby the flat edge of adapter plate  46  can abut against the bolt  96  to assure proper positioning. 
     The pointer  44  and the alignment tool  80  may also be used to align the torch  40 . FIGS. 4 and 5 illustrate the use of the pointer  44  on the end of the torch  40 . The pointer  44  is inverted from its position shown in FIG. 2 so that the counter bore  58  is presented upwardly and so that the flanges  54  are at the upper end of the pointer  44 . The pointer  44  is then slipped over a receptacle body  74  having a threaded bore  76  at its lower end. Receptacle body  74  is attached to the torch  40  which includes a torch end flange  70  and a spacer ring  72  at its lower end. The threaded bore  76  normally receives the contact tip used with the torch  40 . However, before mounting the pointer  44  on the torch  40  the contact tip (now shown) is unthreaded and removed from threaded bore  76 . 
     As can be seen in FIG. 4, the small threaded end  66  of threaded stud  64  is threaded within the threaded bore  76  until the flat end  63  abuts against the spacer  72  and the torch and the flange  70 . This fixes the pointer  44  in proper alignment with the torch  40 . 
     The robot is then moved to a position wherein the torch  40  is in alignment with the alignment tool  80  at test station  78 . At this point the sleeve  82  is moved upwardly as shown in FIG. 5 to determine whether or not there is proper alignment. If the sleeve does not slip easily over both flanges  52  and  54  there is improper alignment. If the sleeve does slip over flanges  52  and  54  there is proper alignment. 
     However, in contrast with the alignment of the robot, a certain tolerance for misalignment is permissible for the torch  40 . For example, if the sleeve slips over the lower flange  52  but will not slip over the upper flange  54 , there is still adequate alignment for the torch  40 . But when aligning the robot  10 , the sleeve must slip over both flanges  52 ,  54  for there to be proper alignment. 
     The pointer  44  and the alignment tool  80  provide a simple and quick way to test both the robot and the tool on the robot for proper alignment. The devices are simple and accurate in their ability to test the proper alignment. 
     In the drawings and specification there has been set forth a preferred embodiment of the invention, and although specific terms are employed, these are used in a generic and descriptive sense only and not for purposes of limitation. Changes in the form and the proportion of parts as well as in the substitution of equivalents are contemplated as circumstances may suggest or render expedient without departing from the spirit or scope of the invention as further defined in the following claims.