Method and apparatus for evaluating welds using stress-wave emission techniques

Claim 3

A method according to claim 1 comprising the additional step of: d. generating an output signal indicative of an acceptable weld when the results of said comparisons indicate that the measurements and ratios thereof being compared exceed the minimum predetermined acceptable value for such measurements and their ratios.

Claim 6

Apparatus for detecting and measuring stress waves propagating from a weld area between first and second articles being welded together for the real-time, non-destructive evaluation of said weld, the apparatus comprising: a. a sensor for detecting stress waves propagating in the material of said articles and generating an electrical output representative of the detected waves; b. a first signal-processing means comprising: i. an amplifier for amplifying the electrical output from said sensor; and ii. a band-pass filter connected to the output of said amplifier for generating an analog output signal within a pass band falling outside the range of frequencies normally generated by components in proximity to the apparatus; c. second signal-processing means connected to the output of said first signal-processing means for measuring the stress-wave energy in each of n time intervals of a weld cycle, where n≧4, each interval corresponding to a different aspect occuring in the weld area during the weld cycle; d. means for comparing measurements selected from any combination of stress-wave energy represented in corresponding ones of said n time intervals and the corresponding ratios between at least two of said time interval measurements to predetermined acceptable ranges to determine the acceptability of the weld.

Claim 7

Apparatus for detecting and measuring stress waves propagating from a weld area between first and second articles being welded together for the real-time, non-destructive evaluation of said weld, the apparatus comprising: a. a sensor for detecting stress waves propagating in the material of said articles and generating an electrical output representative of the detected waves; b. a first signal-processing means comprising: i. an amplifier for amplifying the electrical output from said sensor; and ii. a band-pass filter connected to the output of said amplifier for generating an analog output signal within a pass band falling outside the range of frequencies normally generated by components in proximity to the apparatus; c. second signal-processing means connected to the output of said first signal-processing means for measuring the stress-wave energy in each of n time intervals of a weld cycle, where n≧4, each interval corresponding to a different aspect occuring in the weld area during the weld cycle; d. means for comparing measurements selected from any combination of stress-wave energy represented in corresponding ones of said n time intervals and the corresponding ratios between at least two of said time interval measurements to predetermined acceptable ranges to determine the acceptability of the weld.

Claim 8

Apparatus according to claim 4 wherein said second signal-processing means comprises: i. encoding means, connected to the output of said first signal-processing means, for generating a digital signal indicative of the energy of the output signal of said first signal-processing means; and ii. means for separately counting the digital pulses from said encoding means during each of said n time intervals.

Claim 9

Apparatus according to claim 5 wherein said encoding means comprises: a multiplier circuit for squaring the output signal from said first signal-processing means, and voltage control oscillator circuitry connected to said multiplier circuit for generating a digital frequency-modulated signal indicative of the energy of said squared signal from said multiplier circuit.

Claim 10

Apparatus according to claim 5 wherein said means for separately counting the digital pulses comprises: a plurality of n counters, one for each of said n time intervals; and timing means for gating the digital signal from said encoding means associated with each of said n time intervals into the corresponding one of said plurality of n counters.

Claim 11

Apparatus according to claim 4 wherein said second signal-processing means comprises: means for comparing the measurements from any combination of selected ones of said n time intervals and the ratio between at least two of said time intervals with predetermined acceptable ranges for such measurements and their ratios, and generating an output signal indicative of an acceptable weld when each of said compared measurements and ratios exceeds the minimum predetermined acceptable value for such measurements and their ratios.

Claim 12

Apparatus for detecting and measuring stress waves propagating from a weld area between first and second articles being welded together, for the real-time, non-destructive evaluation of said weld, the apparatus comprising: a. a sensor for detecting stress waves propagating in the material of said articles to produce an electrical output representative of the detected waves; b. first signal-processing means comprising: i. an amplifier for amplifying the electrical output from said sensor, and ii. a band-pass filter connected to the output of said amplifier for generating an analog output signal within a pass-band falling outside the range of frequencies normally generated by components in proximity to the apparatus; and c. second signal-processing means comprising: i. encoding means, connected to the output of said first signal-processing means, for generating a digital signal indicative of the stress-wave energy in the output signal of said first signal-processing means; ii. means connected to the output of said encoding means for separately measuring the stress-wave energy in each of n time intervals of a weld cycle, where n≧4, each time interval corresponding to a different aspect occurring in the weld area during the weld cycle; and iii. means for comparing the measurements from any combination of selected one of said n time intervals and the ratio between at least two of said time interval measurements with predetermined acceptable ranges for such measurements and their ratios.

Claim 13

Apparatus for detecting and measuring stress waves propagating from a weld area between first and second articles being welded together, for the real-time, non-destructive evaluation of said weld, the apparatus comprising: a. a sensor for detecting stress waves propagating in the material of said articles to produce an electrical output representative of the detected waves; b. first signal-processing means comprising: i. an amplifier for amplifying the electrical output from said sensor, and ii. a band-pass filter connected to the output of said amplifier for generating an analog output signal within a pass-band falling outside the range of frequencies normally generated by components in proximity to the apparatus; and c. second signal-processing means comprising: i. encoding means, connected to the output of said first signal-processing means, for generating a digital signal indicative of the stress-wave energy in the output signal of said first signal-processing means; ii. means connected to the output of said encoding means for separately measuring the stress-wave energy in each of n time intervals of a weld cycle, where n≧4, each time interval corresponding to a different aspect occurring in the weld area during the weld cycle; and iii. means for comparing the measurements from any combination of selected one of said n time intervals and the ratio between at least two of said time interval measurements with predetermined acceptable ranges for such measurements and their ratios.

Claim 14

Apparatus according to claim 9 wherein said second signal-processing comparing means further comprises: means for generating an output signal indicative of an acceptable weld when each of said compared measurements and ratios exceeds the minimum predetermined acceptable value for such measurements and their ratios.