Automated Fastener Setting Tool

Abstract

A fastener setting device includes a monitoring circuit having circuitry to receive a feed status signal from a first sensor within the feed system. The circuitry receives a robotic arm status signal from a second sensor within the robotic arm and receives a rivet set status signal from a third sensor within the setting tool. The circuit determines if a fault condition occurs; and initiates a rivet clearing procedure if a fault condition is detected.

What is claimed is: 
     
         1 . A system for setting a self-piercing rivet, said system comprising:
 a self-piercing rivet setting tool, said tool including a rivet engaging assembly, an axially movable piston assembly operatively coupled to said rivet for driving said rivet, a housing annularly disposed about said piston;   a monitoring circuit, having circuitry to:
 (a) receive a feed status signal from a first sensor within the feed system; 
 (b) receive a robotic arm status signal from a second sensor within the robotic arm; 
 (c) receive a rivet set status signal from a third sensor within the setting tool; 
 (d) determine if a fault condition is detected; and 
 (e) initiate a rivet clearing procedure if a fault condition is detected. 
   
     
     
         2 . The system for setting a self-piercing rivet of  claim 1  wherein said monitoring circuit further includes circuitry to:
 produce from a series of feed status signals and a measured rivet set status dataset; 
 scan said measured rivet set status dataset to determine a first local feed value; 
 scan an example rivet set status dataset to determine a second local feed value; and 
 determine if the first local feed value and the second local feed value are within one of a predetermined time tolerance band, or within a predetermined feed tolerance band. 
 
     
     
         3 . The system of  claim 1  wherein the first sensor is configured to measure feed of a fastener along an axial direction. 
     
     
         4 . The system for setting a self-piercing rivet of  claim 1  further including an indicator operatively connected to said monitoring circuit for signaling to an operator the acceptability of a fastener feed based on said comparison of said feed output/ predetermined value pairs. 
     
     
         5 . The system of  claim 1  wherein said first sensor is a micro-strain sensor. 
     
     
         6 . The system of  claim 1  wherein the housing comprises a C-shaped structure. 
     
     
         7 . The system of  claim 1  wherein the first sensor is positioned on an exterior surface of the feed system. 
     
     
         8 . The system according to  claim 1  wherein the body defines a sensor mounting location, said sensor mounting location being at a point on the feed system which experiences deformation during a rivet feed event. 
     
     
         9 . A method of setting a fastener with a setting tool having an axially movable piston assembly operatively coupled to an engaging assembly for driving said fastener in response to the application of pressurized hydraulic fluid to said piston assembly, said method including the steps of:
 (a) monitoring the feed status of a feed system during a rivet setting process and producing a series of measured feed/time signals related thereto;   (b) defining an set of example feed/time signals;   (c) aligning the measured feed/time signals to the example feed/time signals; and   (d) identifying the occurrence of an improper feed during the rivet setting process from the feed/time signal based upon misalignment of signals.   
     
     
         10 . The method of  claim 9  further including the steps of:
 producing a rivet set status dataset based on a series of measured force signal; 
 scanning said force signal to determine the point in time during the rivet setting process when the highest value of force occurs; and 
 using said determined point to identify the rivet setpoint. 
 
     
     
         11 . A system for setting a self-piercing fastener and evaluating the acceptability of the set, said system comprising:
 a rivet setting tool, said tool including a C-shaped support body, a feed system, and a rivet engaging assembly configured to drive said fastener;   a first transducer configured to measure a rivet feed within the feed system during a rivet setting process and producing feed status signal related thereto;   a circuit, configured to:
 (a) receive a series of feed status signals and assign an associated time thereto during the rivet setting process; 
 (b) identify the occurrence during the rivet setting process of the last local feed signal; 
 (c) use the occurrence of the last local feed signal to identify the movement of the fastener; 
 (d) determine the total time of said rivet feed process; 
 (e) compare said total time with a predetermined desired value; and 
 (f) compare said feed timing at the last local maximum with a predetermined value. 
   
     
     
         12 . A method of setting a self-piercing rivet with a setting tool having a support body and an axially movable piston assembly operative for driving said rivet, said method including the steps of:
 (a) monitoring an axial fastener feed during a rivet setting process and producing a series of feed signals related thereto;   (b) monitoring the time of said rivet setting process and producing a series of time signals related thereto;   (c) identifying the occurrence during the rivet setting process of an improper feed;   (d) using the occurrence of the improper feed to identify a fault; and   (e) initiate a rivet cleaning process should the fault be detected.   
     
     
         13 . The method of  claim 12  further including the steps of:
 producing a rivet feed status waveform based on said series of feed signals and said series of time signals produced over a rivet feeding process; 
 scanning said rivet feed status waveform to identify the location of a feed peak in said waveform; and 
 using the location of the feed peak to identify the total time of the rivet feed event. 
 
     
     
         14 . The method for setting a self-piercing rivet according to  claim 13  including comparing the rivet feed status waveform with an example rivet feed status waveform to determine if the rivet feed is acceptable. 
     
     
         15 . An electronic control system for use in a riveting process, the system comprising:
 an electronic control unit;   a drive connected to the electronic control unit;   a feed sensor connected to the electronic control unit and the drive, the feed sensor being operable to indicate changes in feed status within the feed system during the rivet feeding process; and   wherein the electronic control unit is configured to compare the changes in feed system with a predetermined value to determine if a rivet feed status is acceptable.   
     
     
         16 . The system of  claim 15  further comprising a rivet wherein the drive is a hydraulic drive. 
     
     
         17 . The system of  claim 16  further comprising:
 a rivet feeder having an actuator connected to the electronic control unit; and 
 a feed tube sensor connected to the electronic control unit; 
 wherein the electronic control unit operably controls feeding of the rivet by the feeder during the riveting process and the feed tube sensor sends a signal to the electronic control unit indicative of the presence of the rivet. 
 
     
     
         18 . The system of  claim 15  further comprising a punch and a piston, the piston being operable to convert hydraulic pressure to linear motion driving the punch. 
     
     
         19 . The system of  claim 18  wherein the piston is operable to convert pneumatic pressure to linear motion. 
     
     
         20 . The system of  claim 15  further comprising a second sensor being operable to measure one of: (a) torque of an electric motor, (b) speed of the drive, (c) a power characteristic of an electric motor, (d) a punch location, (e) rivet size. 
     
     
         21 . The system of  claim 15  wherein the system comprises a second sensor configured to measure a workpiece thickness. 
     
     
         22 . The system of  claim 15  wherein the second sensor is a load cell operably indicating a linearly moving member force.