Abstract:
An apparatus, tool and method for clearing a rivet from an automated riveting tool. The riveting tool has a nose that supports the rivet as the rivet is installed by a punch. A clamping ring engages a work piece while installing the rivet. A clamping ring engages a block, but defines a clearance area into which the rivet is ejected when an unsuitable rivet is detected. A sensor monitors the rivets in the nose and prevents installation of the rivet when the rivet in the nose is not suitable for installation. System controls are provided to stop insertion of an unsuitable rivet while the robot continues to move the rivet tool through the complete cycle without inserting rivets until the unsuitable rivet is cleared.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure relates to automated riveting tools that are used to install rivets in an assembly and a method of riveting that includes an automated routine for clearing a damaged or improper rivet from the tool. 
       BACKGROUND 
       [0002]    Rivets are used to secure multiple parts together in an assembly. A self-piercing rivet is a tubular member including a head that is installed by a punch and a die that drive the rivet into a work piece. The tubular end of the self-piercing rivet is spread apart as it is installed to provide a permanent, leak proof joint. 
         [0003]    A self-piercing riveting tool has a hollow nose through which the punch and rivet are guided prior to performing the riveting operation. The nose includes an outer ring that clamps the parts of the work piece together before the rivet is inserted into the work piece. Rivets can be damaged, jammed or miss-fed into the tool during the riveting process. Riveting tools can be used to insert a plurality of different types of rivets, different size rivets, or rivets made of different materials in the same part in predetermined locations. If a rivet is jammed in the nose of the rivet tool or the wrong type of rivet is provided to the tool, the rivet must be cleared to prevent damage to the tool or installation of the wrong type of rivet in the wrong location on the work piece. 
         [0004]    The nose of a prior art riveting tool must be disassembled to clear a damaged, jammed or miss fed rivet from the riveting tool. Disassembly of the nose of the riveting tool may take several minutes or longer. In high production environments where multiple rivets are installed by a single riveting tool, after the tool is cleared the automation system must be reset. The time for clearing the damaged, jammed or miss fed rivet plus the time for resetting the automation system compromises the efficiency of the system. 
         [0005]    The above problems and other problems are addressed by this disclosure as summarized below. 
       SUMMARY 
       [0006]    According to one aspect of this disclosure, an apparatus for clearing a rivet from a riveting tool having a nose that supports a rivet as the rivet is installed by a punch. A clamping ring is operative to engage a work piece while installing the rivet. The apparatus comprises a block engaged by the clamping ring that defines a clearance area into which the rivet is moved when an unsuitable rivet is detected in the riveting tool. 
         [0007]    According to other aspects of this disclosure, the clearance area may be an opening through the block. The clearance area may be an edge of the block. The block may be located at a fixed location in close proximity to the riveting tool. 
         [0008]    According to another aspect of this disclosure, a tooling system is disclosed for installing a plurality of rivets in a plurality of locations on a work piece. The tooling system comprises a riveting tool having a ring encircling a punch that engages the work piece to drive the rivet into a work piece. The riveting tool has a nose that encloses the punch and receives the rivets. A robot moves the riveting tool in a programmed sequence to install the rivets in the plurality of locations. A sensor may monitor the presence of the rivet in the nose and the logic in the controller may check in memory the type of rivet previously loaded in the nose and prevent installation of the rivet when the rivet in the nose is not suitable for installation. A controller interrupts the programmed sequence when the rivet detection system prevents installation of a rivet and sets up the clear rivet cycle. The clear rivet cycle can be initiated automatically or manually depending upon the program configuration. During the clear rivet cycle, the ring of the riveting tool is moved into engagement with a block and the punch is cycled to clear the rivet from the nose. The riveting tool is then moved according to the programmed sequence. The clear rivet cycle can be performed manually by the operator for manual gun applications. 
         [0009]    According to other aspects of this disclosure as it relates to the tooling system, the clear rivet cycle begins at a point in the sequence where the rivet that is not suitable for installation is detected. Once the clear rivet cycle is triggered, automatically or by manual intervention, the riveting tool continues through to an end of the programmed sequence without installing any rivets. The rivet is then cleared from the nose and the riveting tool then continues at the beginning of the programmed sequence until the point in the sequence where the rivet that was deemed not suitable for installation was detected. The riveting tool then resumes installing the rivets in the programmed sequence. 
         [0010]    According to other aspects of the disclosure relating to the tooling system, the controller may interrupt the programmed sequence by inhibiting the punch from driving the rivet into the work piece. The rivet detection system may detect the type of rivet in the nose, the condition of the rivet in the nose, or whether the rivet is jammed in the nose. 
         [0011]    According to another aspect of this disclosure, a method is disclosed for installing a plurality of rivets in a work piece with a riveting tool that is moved by a robot. The method comprises installing the rivets in the work piece in a programmed sequence and detecting that a rivet is not suitable for installation. A clear rivet cycle is then initiated by moving the riveting tool to a block that opposes a clamping ring of the riveting tool as a punch drives the rivet from the riveting tool into a clearance area defined by the block. The method continues by resuming installing the rivets in the programmed sequence. 
         [0012]    According to other aspects of the method, the clear rivet cycle is setup when a rivet is detected that is not suitable for installation. Once the clear rivet cycle is triggered, automatically or by manual intervention, the riveting tool continues through to an end of the programmed sequence without installing any rivets, until the rivet is cleared from the riveting tool. The method may then continue at the beginning of the programmed sequence until the point in the sequence where the unsuitable rivet was identified and the riveting tool then resumes installing the rivets in the programmed sequence. 
         [0013]    The above aspects of the disclosure are more fully described below with reference to the attached drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a diagrammatic view of an automated self-piercing riveting tool that includes a robot for moving and operating the riveting tool to install a plurality of rivets in a work piece. 
           [0015]      FIG. 2  is a side elevation view of the automated self-piercing riveting tool engaging a rivet clearing block that defines a rivet rejection opening. 
           [0016]      FIG. 3  is a fragmentary cross-sectional view of a nose of the automated self-piercing riveting tool and the rivet clearing block shown in  FIG. 2 . 
           [0017]      FIG. 4  is a fragmentary cross-sectional view of a nose of the automated self-piercing riveting tool and an alternative embodiment of a rivet clearing block that is engaged on an edge to reject the rivet. 
           [0018]      FIG. 5  is flow chart illustrating the normal sequence of operation for the automated self-piercing riveting tool and robot. 
           [0019]      FIG. 6  is flow chart illustrating the reject rivet sequence for the automated self-piercing riveting tool and robot. 
           [0020]      FIG. 7  is a flow chart illustrating an example of a logic sequence for controlling the automated self-piercing riveting tool and robot. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    A detailed description of the illustrated embodiments of the present invention is provided below. The disclosed embodiments are examples of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale. Some features may be exaggerated or minimized to show details of particular components. The specific structural and functional details disclosed in this application are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art how to practice the invention. 
         [0022]    Referring to  FIG. 1 , an automated self-piercing rivet (SPR) installation tool system is generally indicated by reference numeral  10 . The system  10  includes a SPR tool  12  that is moved between riveting locations by a robot  14 . It should be understood that automation systems may take different forms and that an automation apparatus could be used in place of the robot  14 . A blow feed type of rivet feeder  16 , or magazine, provides rivets (not shown in  FIG. 1 ) to the SPR tool. A magazine feed or tape feed feed system may be used instead of the blow feed type of system. A SPR controller  18  controls operation of the SPR tool  12 . A robot controller  20  controls operation of the robot  14 . The SPR controller  18  and robot controller  20  are interfaced with each other and various control functions may be performed by either the SPR controller  18  or the robot controller  20 . A rivet supply line  24 , or tube, provides a supply of rivets from the rivet feeder  16  to the SPR tool  12 . 
         [0023]    Referring to  FIG. 2 , the SPR tool  12  is shown in greater detail. The rivet supply line  24  is shown feeding rivets to the SPR tool  12 . The SPR tool  12  includes a servo motor actuator  26  that provides the force for driving the rivets into a work piece. A hydraulic actuator or a pneumatic actuator could be used instead of the illustrated servo motor actuator  26 . The SPR tool  12  includes a nose  28  into which rivets are fed by the rivet supply line  24 . A C-shaped jaw  30  forms part of the SPR tool  12  and supports a back-up  32  that is used to support the obverse side of a work piece during a riveting operation. 
         [0024]    In one embodiment, a sensor  34  may be used to detect the presence of the rivet. The sensor may be a proximity sensor, a laser identification sensor, a scale, or other type of sensor. Alternatively, logic may be used to track the type, condition or orientation of a rivet in the nose  28 . The logic may be resident in one or both of the SPR controller  18  and robot controller  20 . The sensor  34  and logic may be used in combination to detect the type, condition, and orientation of the rivet  40 . As used herein, the term “rivet detection system” should be interpreted to include a sensor  34 , logic used to track the type, condition or orientation of a rivet in the nose  28 , or a combination of the sensor  34  and logic. 
         [0025]    A block  36  is provided to facilitate removing rivets from the nose  28  of the SPR tool  12 . The block  36  includes a passageway  38 , or opening, through which a rivet  40  may be driven to clear the rivet  40  from the SPR tool  12 . The illustrated rivet is a countersink rivet  40 , but it should be understood that a pan head or hex head rivet may also be used. 
         [0026]    Referring to  FIG. 3 , one embodiment of the block  36  is shown in which the nose  28  is shown in a fragmentary cross-sectional view. A punch  44  is disposed within and concentric to a ring  46 . A helical mechanical spring  48  urges the ring  46  into engagement with the work piece or with the block  36  that includes passageway  38  for clearing a rivet  40 . A hydraulic or pneumatic pre-clamp may be used instead of the mechanical spring  48 . A body portion  50  of the SPR tool  12  retains the spring  48  and provides a reaction force to the spring  48  in the course of a riveting operation. 
         [0027]    Referring to  FIG. 4 , an alternative block  52  is shown that includes an edge  54 . The SPR tool  12  may engage the edge  54  of the alternative block  52  to hold the ring  46  in place while the punch  44  reciprocates through a riveting cycle. In the embodiment of  FIG. 4 , the ring  46  only partially engages the block  52 , while in the embodiment shown in  FIG. 3 , the ring engages the circumference of the passageway  38  in the block  36 . 
         [0028]    Referring to  FIG. 5 , a diagrammatic view illustrates a work piece  58  undergoing a normal riveting cycle. The robot  14  moves the SPR tool  12  from a location designated riveter home  56  and moves from A to B to C to D, installs rivets as indicated by “O” and returns to home. In contrast,  FIG. 6  illustrates the robot  14  as it moves the SPR tool  12  from riveter home  56  on a work piece  62  that illustrates an interrupted riveting cycle. In  FIG. 6 , an interrupted cycle  62  is illustrated where a rivet is installed as indicated by “O” of A. A defective rivet or otherwise unacceptable rivet is detected at “B”. At this point, the robot  14  continues to move the SPR tool  12  to C and D, but no rivet is installed as indicated by “X” at location C and D. Since the unacceptable condition was detected at B, no rivet is installed at B as indicated by “O”. 
         [0029]    After the robot  14  leaves location D, SPR tool  12  returns to the riveter home position  56 . The robot  14  moves the SPR tool  12  to a rivet clearing station  66 . The block  36  is illustrated at the rivet clearing station  66 . The block includes the passageway  38 , or opening, to which the rivet  40  is ejected by the punch as shown in  FIG. 3 . Upon clearing the rivet  40 , the SPR tool  12  returns to the riveter home position and the riveting cycle begins again. No rivet is installed at A and riveting resumes as the robot  14  moves the SPR tool  12  from B to C to D before returning to the riveter home  56 . 
         [0030]    Referring to  FIG. 7 , a flowchart is provided to illustrate the logic sequence used to clear a rivet  40  from the nose  28  of the SPR tool  12  (not shown in  FIG. 7 ). The description of the logic sequence begins at  70  with the robot at its home position. A work piece is loaded into a fixture, as diagrammatically represented as the box identified by reference numeral  72 . Once the part is in the fixture, operation of the SPR tool  12  begins with a detector determining whether the wrong rivet  40  has been fed into the nose  28  of the SPR tool  12 . If the correct rivet  40  is detected, the SPR tool proceeds to block  76  representing the first rivet point. If the wrong rivet  40  is fed into the nose  28 , the riveting sequence is interrupted and the SPR tool  12  moves to the clear rivet block  80  where the clear rivet cycle is performed at the rivet clearing station  66  (shown in  FIG. 6 ). 
         [0031]    From the first rivet point  76 , the robot waits for the riveting operation to be completed at the first rivet point  76 . If the riveting operation at the first rivet point was not completed, it is determined whether or not there is a fault at block  82 . If no fault has occurred, the system reverts back to block  81 . If a fault is detected at  82 , an operator may be prompted at  84  to initiate the clear rivet at nose cycle at  84 . In an automatic or semi-automatic system the control logic may be used to start the clear rivet nose cycle at  84 . The riveting operation is stopped and the robot continues to move the robot through the riveting path at  86  without installing any rivets at the subsequent riveting locations. The riveting cycle continues without riveting until the robot  12  returns the SPR tool to its home position at  70 . From the home position, the robot moves the SPR tool  12  to the clear rivet block at  80 . From  80 , the robot returns to home at  70  and continues the riveting operation at the location where the robot previously left off. 
         [0032]    Resuming the description of the process after successful insertion of a rivet at the first rivet point at  76 , the robot moves the SPR tool  12  to the second rivet point at  90 . A rivet is installed at  90  and the system checks to determine whether the riveting at the second rivet point was completed at  92 . If not, a fault is determined at  94 . If a fault has occurred, the operator may be prompted to press the clear rivet at nose  96 . Alternatively, the system may be more fully automated by eliminating the need for an operator to press the clear rivet at nose button and the system may automatically direct the robot to continue riveting with no riveting stroke at  86  without intervention by an operator. 
         [0033]    If the riveting is successfully completed at the third rivet point at block  98 , the system checks at  100  as to whether the riveting was successfully completed. If not, again it is determined whether or not a fault has occurred and if so the system proceeds at  104  as previously described. If the riveting is determined to be completed at block  100 , the system proceeds in like manner for the required number of rivets as represented at block  106 . Upon completing all of the riveting operations, the robot returns the SPR tool  12  to home at  70 . 
         [0034]    While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.