David A Chizmar

US Patent:

56660510, Sep 9, 1997

Filed:

Oct 4, 1995

Appl. No.:

8/539241

Inventors:

Warren R. Junker - Monroeville PA
Lee W. Burtner - Elizabeth Twp., Allegheny County PA
Michael G. Peck - Greensburg PA
Richard J. Makar - Greensburg PA
David A. Chizmar - Export PA

Assignee:

Thermo King Corporation - Minneapolis MN

International Classification:

G01R 3312
G01N 2772
G01B 724

US Classification:

324209

Abstract:

Both a system and method are provided for mapping the magnitude of residual compressive stresses over the surface of a ferromagnetic machine component, such as a valve ring of the type used in refrigeration compressors. The system includes an eddy current probe having a detection coil for emanating a fluctuating electromagnetic field that shallowly penetrates the surface of the valve ring or other ferromagnetic component, a probe circuit connected to the coil for both conducting a high frequency alternating electric current through the coil and detecting changes in the impedance in the coil, and a scanning mechanism having a turntable for supporting and rotating the component. A support arm positions the coil of the eddy current over a central portion of the valve ring while the ring is rotated by the turntable and changes in coil impedance are detected by the probe circuit. A microprocessor converts the fluctuations in the impedance detected by the eddy current probe circuit into residual stress values, and correlates these values with regular positions on the valve ring in order to generate a map of the residual surface stresses over the ring.

US Patent:

45786437, Mar 25, 1986

Filed:

Nov 18, 1983

Appl. No.:

6/553346

Inventors:

Warren R. Junker - Monroeville PA
Bruce J. Taszarek - Mt. Lebanon PA
David A. Chizmar - Export PA

Assignee:

Westinghouse Electric Corp. - Pittsburgh PA

International Classification:

G01R 3500
G01N 2782

US Classification:

324202

Abstract:

An apparatus for simulating and analyzing discontinuities in a tube using eddy current inspection techniques is disclosed. The simulation apparatus includes inner and outer tubular members arranged to define an annular chamber having a predetermined tubular configuration corresponding to the tubular configuration of a tube under investigation. The outer tubular member has an opening through the wall thereof and the inner tubular member defines an axially extending hollow interior. A supply of electrically conductive liquid material is provided in the annular chamber, the quantity of liquid material being such as to substantially and completely fill the annular chamber in the vicinity of the opening through the wall of the outer tubular member. A defect simulation member is supported in the opening in the outer tubular member for movement along a predetermined direction extending transverse to the axis of the inner tubular member. Further, an eddy current test probe is positioned in the hollow interior of the inner tubular member adjacent the position of the defect simulation member for generating eddy current responses which are representative of the eddy current responses which would be obtained for a tube having a configuration corresponding to the predetermined tubular configuration and having a discontinuity in the wall thereof corresponding to the predetermined type of discontinuity.

US Patent:

45862494, May 6, 1986

Filed:

Dec 30, 1983

Appl. No.:

6/567107

Inventors:

Annette M. Costlow - Plum Borough PA
David A. Chizmar - Export PA
Frank W. Cooper - Monroeville PA

Assignee:

Westinghouse Electric Corp. - Pittsburgh PA

International Classification:

B23P 1900
B23P 1700
G01B 714

US Classification:

29723

Abstract:

An improved fluid mandrel having an eddy current probe connected thereto is disclosed herein. The eddy current probe generally comprises a probe body which is detachably connectable to the bottom of a fluid mandrel on one end, and a source of hydraulic fluid on the other end. The probe body includes a pair of sensing coils which are separated along the longitudinal axis of the body by a distance approximately equal to the thickness of the metallic structure desired to be detected. The improved mandrel finds particular application in performing expansions which eliminate the clearance between heat exchange tubes extending through the baffle plates in nuclear steam generators. In such an application, the sensing coils of the probe are longitudinally spaced the same distance as the thickness of the baffle plates in order to generate a sharp and unambiguous electronic signal indicative of the relative positions of the mandrel and the baffle plate.