Blind rivet set verification system and method
First Claim
1. A system for setting a blind rivet and evaluating the acceptability of the set, said rivet being of the type having a frangible tubular body and an elongated mandrel that includes an enlarged head and a stem extending rearwardly of the head and through said frangible tubular body, said system comprising:
- a hydraulically operated blind rivet setting tool, said tool including a rivet engaging assembly for engaging said stem of said mandrel and an axially movable piston assembly operatively coupled to said rivet engaging assembly for driving said mandrel in response to the application of pressurized hydraulic fluid to said piston assembly;
a first transducer for monitoring the pressure of the hydraulic fluid applied to said, piston assembly during a rivet setting process and producing pressure output signals related thereto;
a second transducer operatively associated with said tool for producing displacement output signals related to the movement of said piston assembly in the axial direction during the rivet setting process; and
a control circuit, said control circuit having circuitry to;
(a) receive a series of said pressure output signals and a series of said displacement output signals during the rivet setting process;
(b) determine from said series of displacement output signals the velocity of said piston assembly during the rivet setting process;
(c) identify the occurrence during the rivet setting process of the highest value of velocity;
(d) use the occurrence of the highest value of velocity to identify the mandrel breakpoint; and
(e) compare a breakpoint load value determined from the value of the pressure output signal at the mandrel breakpoint with a predetermined desired value.
3 Assignments
0 Petitions
Accused Products
Abstract
A blind rivet set verification system for setting a blind rivet assessing the acceptability of the rivet set. The system includes a remote intensified rivet setting tool and computer hardware and software. The tool comprises a displacement transducer that produces a displacement signal and a pressure transducer that produces a pressure signal. The transducers are connected to the computer which receives the distinct signals. These signals are interpreted to plot a displacement-versus pressure waveform and to determine the velocity of the movement of an air piston that responds to the rivet set by hydraulic pressure. Using the combined date of the velocity waveform and the displacement-versus pressure waveform, the breakload is identified and compared against predetermined ideal data to assess the acceptability of the set. The displacement reading at break is corrected for jaw slippage and offset of the air piston.
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Citations
37 Claims
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1. A system for setting a blind rivet and evaluating the acceptability of the set, said rivet being of the type having a frangible tubular body and an elongated mandrel that includes an enlarged head and a stem extending rearwardly of the head and through said frangible tubular body, said system comprising:
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a hydraulically operated blind rivet setting tool, said tool including a rivet engaging assembly for engaging said stem of said mandrel and an axially movable piston assembly operatively coupled to said rivet engaging assembly for driving said mandrel in response to the application of pressurized hydraulic fluid to said piston assembly; a first transducer for monitoring the pressure of the hydraulic fluid applied to said, piston assembly during a rivet setting process and producing pressure output signals related thereto; a second transducer operatively associated with said tool for producing displacement output signals related to the movement of said piston assembly in the axial direction during the rivet setting process; and a control circuit, said control circuit having circuitry to; (a) receive a series of said pressure output signals and a series of said displacement output signals during the rivet setting process; (b) determine from said series of displacement output signals the velocity of said piston assembly during the rivet setting process; (c) identify the occurrence during the rivet setting process of the highest value of velocity; (d) use the occurrence of the highest value of velocity to identify the mandrel breakpoint; and (e) compare a breakpoint load value determined from the value of the pressure output signal at the mandrel breakpoint with a predetermined desired value. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of setting a blind rivet having a mandrel with a setting tool having a mandrel engaging assembly for engaging said mandrel and an axially movable piston assembly operatively coupled to said engaging assembly for driving said mandrel in response to the application of pressurized hydraulic fluid to said piston assembly;
- said method including the steps of;
(a) monitoring the pressure of the hydraulic fluid applied to said piston assembly during a rivet setting process and producing a series of pressure signals related thereto; (b) monitoring the movement of said piston assembly in the axial direction during said rivet setting process and producing a series of displacement signals related thereto; (c) determining from said series of displacement signals the velocity of said piston assembly during the rivet setting process; (d) identifying the occurrence during the rivet setting process of the highest value of velocity; (e) using the occurrence of the highest value of velocity to identify the mandrel breakpoint; (f) comparing a breakpoint load value determined from the value of the pressure signal at the mandrel breakpoint with a predetermined desired value. - View Dependent Claims (8)
- said method including the steps of;
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9. A system for setting a blind rivet and evaluating the acceptability of the set, said rivet being of the type having a frangible tubular body and an elongated mandrel that includes an enlarged head and a stem extending rearwardly of the head and through said frangible tubular body, said system comprising:
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a hydraulically operated blind rivet setting tool, said tool including a rivet engaging assembly for engaging said stem of said mandrel and an axially movable piston assembly operatively coupled to said rivet engaging assembly for driving said mandrel in response to the application of pressurized hydraulic fluid to said piston assembly; a first transducer for monitoring the pressure of the hydraulic fluid applied to said piston assembly during a rivet setting process and producing pressure output signals related thereto; a second transducer operatively associated with said tool for producing displacement output signals related to the movement of said piston assembly in the axial direction during the rivet setting process; and a control circuit, said control circuit having circuitry to; (a) receive a series of said pressure output signals and a series of said displacement output signals during the rivet setting process; (b) identify the occurrence during the rivet setting process of the peak pressure; (c) use the occurrence of the pressure peak to identify the break of the mandrel; (d) determine the total displacement of said piston assembly at the break of the mandrel; and (e) compare said total displacement with a predetermined desired value. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method of setting a blind rivet having a mandrel with a setting tool having a mandrel engaging assembly for engaging said mandrel and an axially movable piston assembly operatively coupled to said engaging assembly for driving said mandrel in response to the application of pressurized hydraulic fluid to said piston assembly;
- said method including the steps of;
(a) monitoring the pressure of the hydraulic fluid applied to said piston assembly during a rivet setting process and producing a series of pressure signals related thereto; (b) monitoring the movement of said piston assembly in the axial direction during said rivet setting process and producing a series of displacement signals related thereto; (c) identifying the occurrence during the rivet setting process of a peak pressure; (d) using the occurrence of the peak pressure to identify the breakpoint of the mandrel; (e) determining the total displacement of the piston assembly at the mandrel breakpoint; and (f) comparing the total displacement with a predetermined desired value. - View Dependent Claims (18, 19, 20, 21)
- said method including the steps of;
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22. A system for setting a blind rivet and evaluating the acceptability of the set, said rivet being of the type having a frangible tubular body and an elongated mandrel that includes an enlarged head and a stem extending rearwardly of the head and through said frangible tubular body, said system comprising:
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a hydraulically operated blind rivet setting tool, said tool including a rivet engaging assembly for engaging said stem of said mandrel and an axially movable piston assembly operatively coupled to said rivet engaging assembly for driving said mandrel in response to the application of pressurized hydraulic fluid to said piston assembly; a transducer operatively associated with said tool for producing displacement output signals related to the movement of said piston assembly in the axial direction during the rivet setting process; and a control circuit, said control circuit having circuitry to; (a) receive a series of said displacement output signals over time; (b) determine from said series of displacement output signals the velocity of said piston assembly during the rivet setting process; (c) determine a lowest initial velocity value; (d) determine a peak velocity value subsequent to said lowest initial velocity value; (e) determine the difference between said lowest initial velocity value and said peak velocity value; and (f) compare the determined difference with a predetermined desired value. - View Dependent Claims (23, 24, 25, 26, 27)
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28. A method of setting a blind rivet having a mandrel with a setting tool having a mandrel engaging assembly for engaging said mandrel and an axially movable piston assembly operatively coupled to said engaging assembly for driving said mandrel in response to the application of pressurized hydraulic fluid to said piston assembly;
- said method including the steps of;
(a) monitoring the movement of said piston assembly in the axial direction during the rivet setting process and producing a series of displacement signals; (b) determining from said series of displacement signals the velocity of said piston assembly; (c) determining a lowest initial value of velocity; (d) determining a peak velocity value subsequent to said lowest initial velocity value; (e) determining the difference between said lowest initial velocity value and said peak velocity value; and (f) comparing said difference to a predetermined desired value. - View Dependent Claims (29, 30)
- said method including the steps of;
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31. A system for setting a blind rivet and evaluating the acceptability of the set, said rivet being of the type having a frangible tubular body and an elongated mandrel that includes an enlarged head and a stem extending rearwardly of the head and through said frangible tubular body, said system comprising:
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a hydraulically operated blind rivet setting tool, said tool including a rivet engaging assembly for engaging said stem of said mandrel and an axially movable piston assembly operatively coupled to said rivet engaging assembly for driving said mandrel in response to the application of pressurized hydraulic fluid to said piston assembly; a first transducer for monitoring the pressure of the hydraulic fluid applied to said piston assembly during a rivet setting process and producing pressure output signals related thereto; a second transducer operatively associated with said tool for producing displacement output signals related to the movement of said piston assembly in the axial direction during the rivet setting process; and a control circuit, said control circuit having circuitry to; (a) receive a series of said pressure output signals and a series of said displacement output signals; (b) determine from said series of displacement output signals the velocity of said piston assembly during the rivet setting process; (c) determine the occurrence of a lowest initial value of velocity, this value representing the point in time during the rivet setting process when the mandrel head enters the rivet body; (d) determine the value of the pressure output signal at said point in time when the mandrel head enters the rivet body; and (e) compare said pressure value with a predetermined desired value. - View Dependent Claims (32, 33, 34, 35)
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36. A method of setting a blind rivet having a tubular body and a mandrel with an enlarged head portion and an elongated stem portion extending through said body, with a setting tool having a mandrel engaging assembly for engaging said mandrel and an axially movable piston assembly operatively coupled to said engaging assembly for driving said mandrel in response to the application of pressurized hydraulic fluid to said piston assembly;
- said method including the steps of;
(a) monitoring the pressure of the hydraulic fluid applied to said piston assembly during a rivet setting process and producing a series of pressure signals related thereto; (b) monitoring the movement of said piston assembly in the axial direction during said rivet setting process and producing a series of displacement signals related thereto; (c) determining from said series of displacement signals the velocity of said piston assembly during the rivet setting process; (d) determining the occurrence of a lowest initial velocity value, said lowest initial velocity value representing the point in time during the rivet setting process when the mandrel head enters the rivet body; (e) determining the value of said pressure output signal at said point in time when the mandrel head enters the rivet body; and (f) comparing said pressure value to a predetermined desired value. - View Dependent Claims (37)
- said method including the steps of;
Specification