Nondestructive real-time method for monitoring the quality of a weld

• US 4,419,562 A
• Filed: 01/19/1982
• Issued: 12/06/1983
• Est. Priority Date: 01/19/1982
• Status: Expired due to Term

• Current Assignee: AT&T Technologies Inc (Nokia Corporation)
• Original Assignee: Western Electric Co., Inc. (Nokia Corporation)
• Inventors: Palazzo, Vito, Jon, Min-Chung
• Primary Examiner(s): Shaw, C. C.
• Application Number:
  US06/340,607
• Time in Patent Office: 686 Days
• Field of Search: 219/130.01, 219/130.21, 219/121 LB, 228/104
• US Class Current: 219/130.01
• CPC Class Codes: B23K 15/0013 Positioning or observing workpieces, e.g. with respect to the impact; Aligning, aiming or focusing electronbeams
• CPC Class Codes: B23K 26/03 Observing, e.g. monitoring, the workpiece
• CPC Class Codes: B23K 37/00 Auxiliary devices or processes, not specially adapted to a procedure covered by only one of the preceding main groups eye-shields for welders worn on the operator's body or carried in the hand A61F9/00 , i.e. A61F9/02; applicable to metal-working machines other than soldering, welding, or flame-cutting machines B23Q; laser protective screens B23K26/706; protective shields for other welding methods F16P1/06

Abstract

Herein disclosed is a noncontact, nondestructive method for monitoring the quality of a high energy weld, e.g., laser beam weld. In accordance with the proposed method, an acoustic sensor (32) is positioned at a distance from the welding zone (34) and picks up airborne acoustic emission signals (33) associated with the laser welding process. These acoustic signals, propagating through the air space between the welding zone (34) and the sensor (32), are detected and analyzed (36,37) to determine the quality of the weld (FIG. 3).

Claims

1. Method for monitoring the quality of a weld on a workpiece comprising the steps of:

positioning a high frequency wideband acoustic emission sensor in noncontact spaced relation with the workpiece and in noncontact spaced relation with the weld site on said workpiece;

detecting at said acoustic emission sensor airborne shock wave signals propagating away from the weld site and having a frequency above 100 KHz; and

analyzing the detected high frequency acoustic emission signals thereby determining the quality of the weld.

3. Method for monitoring the quality of a weld according to claims 1 or 2, wherein the positioning step comprises the step of:

attaching said high frequency acoustic emission sensor to the surface of a metal plate; and

positioning said metal plate at a predetermined distance from said workpiece.

4. Method for monitoring the quality of a weld according to claim 3, wherein said metal plate is positioned between said workpiece and a welding source.

2. Method for monitoring the quality of a weld on a workpiece comprising the steps of:

directing a high energy welding beam toward a weld site on the workpiece thereby forming a plume at said weld site;

positioning a high frequency wideband acoustic emission sensor in noncontact spaced relation with the workpiece and in noncontact spaced relation with the weld site;

detecting at said acoustic emission sensor airborne shock wave signals propagating away from the plume and having a frequency above 100 KHz; and

analyzing the detected high frequency acoustic emission signals thereby determining the quality of the weld.