US 5,661,887 A · Blind rivet set verification system and method

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.

8 more elements

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) 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.

8 more elements

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.

5 more elements

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 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.

8 more elements

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;
(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.

8 more elements

Blind rivet set verification system and method

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Blind rivet set verification system and method

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Abstract

Claims37