US3700850A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for detecting the amount of material removed by a laser
Assignee: AT&T Inc
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Filing: 1970-09-04
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Granted: 1972-10-24
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Expires: 1990-09-04
Abstract
Abstract A pulsed or Q-switched laser removes material from a workpiece during a numerically-controlled machining process. The amount of material removed after each laser pulse is monitored by measuring the time taken for the shock waves generated by the laser pulse to traverse the remaining portion of the workpiece.
Inventors
- 👤 Robert Miller Lumley
- 👤 Victor John Tarassov
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:16
CPC Classifications
B; B23; B23K; B23K26/00; B23K26/02; B23K26/04
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
106 words
A method of removing a predetermined amount of material from a workpiece, comprising the steps of: applying a beam of radiant energy to said workpiece to effect material removal therefrom, the impingement of said beam generating an acoustical shock wave in said workpiece; measuring the time interval required for said shock wave to traverse said workpiece from the point of impact of said beam to a sensor positioned proximate said workpiece; and repeating the application of said beam to said workpiece until said time interval corresponds to some predetermined value indicative of the fact that said predetermined amount of material has been removed from said workpiece.
Claim 2
Independent Claim
106 words
A method of removing a predetermined amount of material from a workpiece, comprising the steps of: applying a beam of radiant energy to said workpiece to effect material removal therefrom, the impingement of said beam generating an acoustical shock wave in said workpiece; measuring the time interval required for said shock wave to traverse said workpiece from the point of impact of said beam to a sensor positioned proximate said workpiece; and repeating the application of said beam to said workpiece until said time interval corresponds to some predetermined value indicative of the fact that said predetermined amount of material has been removed from said workpiece.
Claim 3
Dependent Claim
97 words
The method according to claim 1, wherein said sensor generates a first electrical signal when said shock wave impinges thereon, and said measuring step further comprises: enabling the operation of a digital clock circuit upon application of said radiant energy beam to said workpiece, said clock circuit generating a continuous train of clock pulse when so enabled; counting said train of pulses in a digital counter connected tO said clock circuit; and terminating the count in said counter upon receipt of said first electrical signal, the count stored in said counter being proportional to said time interval.
Claim 4
Dependent Claim
48 words
The method according to claim 2, wherein said repeating step comprises: after each application of said beam to said workpiece, comparing the count stored in said counter with a predetermined count; and terminating the application of said beam to said workpiece when said count equals said predetermined count.
Claim 5
Dependent Claim
47 words
The method according to claim 2, wherein said enabling step further comprises: directing at least a portion of said radiant energy beam onto a radiation detector to generate a second electrical signal; and applying said second electrical signal as an enabling pulse to said digital clock circuit.
Claim 6
Dependent Claim
38 words
The method according to claim 4, wherein said directing step comprises: inserting a beam-spitting device at least partially into the path of said radiant energy beam; and positioning said radiation detector proximate one output of said beam-splitting device.
Claim 7
Dependent Claim
38 words
The method according to claim 1, wherein said beam applying step comprises: applying a laser beam to said workpiece to effect material removal therefrom, the impingement of said laser beam generating an acoustical shock wave in said workpiece.
Claim 8
Dependent Claim
38 words
The method according to claim 1, wherein said beam applying step comprises: applying an electron beam to said workpiece to effect material removal therefrom, the impingement of said electron beam generating an acoustical shock wave in said workpiece.
Claim 9
Independent Claim
131 words
A method of removing a predetermined amount of material from a workpiece comprising the steps of: immersing said workpiece in a medium transparent to radiant energy; applying a beam of radiant energy through said medium onto said workpiece to effect material removal therefrom, the impingement of said beam generating an acoustical shock wave in said workpiece, which shock wave is transmitted into said medium; measuring the time interval required for said shock wave to travel in said medium from the point of impact of said beam to a sensor positioned proximate the surface of said medium; and intermittently repeating the application of said beam to said workpiece until said time interval reaches some predetermined value, indicative of the fact that said predetermined amount of material has been removed from said workpiece.
Claim 10
Independent Claim
131 words
A method of removing a predetermined amount of material from a workpiece comprising the steps of: immersing said workpiece in a medium transparent to radiant energy; applying a beam of radiant energy through said medium onto said workpiece to effect material removal therefrom, the impingement of said beam generating an acoustical shock wave in said workpiece, which shock wave is transmitted into said medium; measuring the time interval required for said shock wave to travel in said medium from the point of impact of said beam to a sensor positioned proximate the surface of said medium; and intermittently repeating the application of said beam to said workpiece until said time interval reaches some predetermined value, indicative of the fact that said predetermined amount of material has been removed from said workpiece.
Claim 11
Dependent Claim
32 words
The method according to claim 8 wherein said sensor is annular in shape and said applying step comprises: directing said beam of radiant energy through the central aperture of said annular-shaped sensor.
Claim 12
Independent Claim
210 words
A method of machining a workpiece to a particular shape by the selective removal of a predetermined amount of material from a plurality of locations on said workpiece comprising the steps of: positioning at least one acoustical sensor proximate a first surface of said workpiece; mounting said workpiece with said sensor attached to a numerically controlled table adapted for motion along at least two axes; energizing said table to advance said workpiece so that a first one of said plurality of locations is positioned beneath a work station; intermittently energizing a source of a beam of radiant energy positioned proximate said work station so that said beam repetitively impinges upon a second surface of said workpiece to effect material removal therefrom, each impingement of the beam generating a shock wave in the workpiece; measuring the time interval required for each of said shock waves to travel through the workpiece from the point of impact of said beam to the location of said sensor; and advancing said table so that a next one of said plurality of locations is positioned beneath said work station when said measured time interval falls below some predetermined value indicative of the removal of said predetermined amount of material from the first location of said workpiece.
Claim 13
Independent Claim
210 words
A method of machining a workpiece to a particular shape by the selective removal of a predetermined amount of material from a plurality of locations on said workpiece comprising the steps of: positioning at least one acoustical sensor proximate a first surface of said workpiece; mounting said workpiece with said sensor attached to a numerically controlled table adapted for motion along at least two axes; energizing said table to advance said workpiece so that a first one of said plurality of locations is positioned beneath a work station; intermittently energizing a source of a beam of radiant energy positioned proximate said work station so that said beam repetitively impinges upon a second surface of said workpiece to effect material removal therefrom, each impingement of the beam generating a shock wave in the workpiece; measuring the time interval required for each of said shock waves to travel through the workpiece from the point of impact of said beam to the location of said sensor; and advancing said table so that a next one of said plurality of locations is positioned beneath said work station when said measured time interval falls below some predetermined value indicative of the removal of said predetermined amount of material from the first location of said workpiece.
Claim 14
Dependent Claim
105 words
Apparatus for removing a predetermined amount of material from a workpiece, which comprises; a source of radiant energy, means for supporting said workpiece proximate said source of radiant energy, means for directing a beam of radiant energy from said source onto said workpiece, a sensor located proximate a first surface of said workpiece to detect the arrival of acoustical shock waves generated in said workpiece by the impact of said beam on a second surface of said workpiece, and means responsive to the time interval required for said shock waves to traverse said workpiece for terminating the application of said radiant energy to said workpiece.
Claim 15
Dependent Claim
105 words
Apparatus for removing a predetermined amount of material from a workpiece, which comprises; a source of radiant energy, means for supporting said workpiece proximate said source of radiant energy, means for directing a beam of radiant energy from said source onto said workpiece, a sensor located proximate a first surface of said workpiece to detect the arrival of acoustical shock waves generated in said workpiece by the impact of said beam on a second surface of said workpiece, and means responsive to the time interval required for said shock waves to traverse said workpiece for terminating the application of said radiant energy to said workpiece.
Claim 16
Dependent Claim
71 words
Apparatus according to claim 11, wherein said terminating means comprises: a digital clock circuit for generating a train of clock pulses; means, connected to said clock circuit, for enabling operation thereof when radiant energy from said source is applied to said workpiece; a digital counter, connected to said clock circuit, for counting said train of pulse; and means, connected to said counter, for discontinuing the operation of said radiant energy source.
Claim 17
Dependent Claim
53 words
The apparatus according to claim 12, wherein said discontinuing means comprises: a digital controller, connected to said digital counter, for comparing the count in said counter with a predetermined count; and means, connected to said digital controller, for deactivating said radiant energy source when the count in said counter equals said predetermined count.
Claim 18
Dependent Claim
30 words
The apparatus according to claim 12, wherein said enabling means comprises: a radiation detector; and means for directing at least a portion of said radiant energy onto said radiation detector.
Claim 19
Dependent Claim
31 words
The apparatus according to claim 14, wherein said energy directing means comprises a beam-splitting device at least partially inserted into the path of the radiant energy from said radiant energy source.
Claim 20
Dependent Claim
15 words
The apparatus according to claim 11, wherein said source of radiant energy comprises a laser.
Claim 21
Dependent Claim
16 words
The apparatus according to claim 11, wherein said source of radiant energy comprises an electron-beam device.
Claim 22
Dependent Claim
139 words
Apparatus for removing a predetermined amount of material from a workpiece, which comprises: a source of radiant energy; a tank containing a medium transparent to said radiant energy, into which said workpiece is immersed; means for directing a beam of radiant energy from said source onto said workpiece to effect material removal therefrom, each impingement of said beam generating an acoustical shock wave in said workpiece; an annular-shaped sensor, positioned proximate the upper surface of said medium, and coaxial with said beam of radiant energy, to detect said shock wave; and means for measuring the time interval required for said shock wave to traverse the distance between the point of impact of said beam of radiant energy on said workpiece and the location of said annular-shaped sensor, to terminate application of the beam of radiant energy to said workpiece.
Claim 23
Dependent Claim
139 words
Apparatus for removing a predetermined amount of material from a workpiece, which comprises: a source of radiant energy; a tank containing a medium transparent to said radiant energy, into which said workpiece is immersed; means for directing a beam of radiant energy from said source onto said workpiece to effect material removal therefrom, each impingement of said beam generating an acoustical shock wave in said workpiece; an annular-shaped sensor, positioned proximate the upper surface of said medium, and coaxial with said beam of radiant energy, to detect said shock wave; and means for measuring the time interval required for said shock wave to traverse the distance between the point of impact of said beam of radiant energy on said workpiece and the location of said annular-shaped sensor, to terminate application of the beam of radiant energy to said workpiece.
Claim 24
Dependent Claim
190 words
Apparatus for machining a workpiece to a particular shape by the selective removal of predetermined amounts of material from a plurality of locations on said workpiece, which comprises: a source of radiant energy; control means connected to said source for controlling the generation of said radiant energy; means for directing a beam of said radiant energy onto a point of application on said workpiece; numerically controlled means for imparting motion to said workpiece along at least two axes to position a first one of said plurality of locations proximate the point of application of said beam; at least one sensor positioned adjacent said workpiece to detect acoustical shock waves generated in said workpiece by the impact of said beam thereon; counting means connected to said sensor and to said control means for measuring the time interval required for said shock waves to traverse said worKpiece; and means responsive to the count stored in said counting means for terminating the application of radiant energy to said first location, and for causing said numerically controlled means to position a second one of said locations proximate the point of application of said beam.
Claim 25
Dependent Claim
190 words
Apparatus for machining a workpiece to a particular shape by the selective removal of predetermined amounts of material from a plurality of locations on said workpiece, which comprises: a source of radiant energy; control means connected to said source for controlling the generation of said radiant energy; means for directing a beam of said radiant energy onto a point of application on said workpiece; numerically controlled means for imparting motion to said workpiece along at least two axes to position a first one of said plurality of locations proximate the point of application of said beam; at least one sensor positioned adjacent said workpiece to detect acoustical shock waves generated in said workpiece by the impact of said beam thereon; counting means connected to said sensor and to said control means for measuring the time interval required for said shock waves to traverse said worKpiece; and means responsive to the count stored in said counting means for terminating the application of radiant energy to said first location, and for causing said numerically controlled means to position a second one of said locations proximate the point of application of said beam.
References Cited (Backward Citations)
US3542995A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-24 | 1976-04-24 | 1976-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-24 | 1980-04-24 | 1980-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-24 | 1984-04-24 | 1984-10-24 | $7700.00 | Window Closed / Lapsed |