Chatter and profile measuring using capacitor sensors

• US 5,272,443 A
• Filed: 04/22/1992
• Issued: 12/21/1993
• Est. Priority Date: 04/22/1992
• Status: Expired due to Fees

• Current Assignee: Alcoa Incorporated (Howmet Aerospace, Inc.)
• Original Assignee: Aluminum Company of Egypt
• Inventors: Ringle, Michael A., Winchip, Wade A.
• Primary Examiner(s): Wieder, Kenneth A.
• Assistant Examiner(s): BROWN, GLENN WARNER
• Application Number:
  US07/872,912
• Time in Patent Office: 608 Days
• Field of Search: 324/662, 324/679, 324/686, 324/690, 73/105, 29/407
• US Class Current: 324/662
• CPC Class Codes: G01B 7/087 for measuring of objects while moving G01B7/085 takes precedence

Abstract

A method and apparatus for measuring chatter marks on a metal workpiece. The method includes first removing gross buckle or curvature in the workpiece by clamping the same in the device having an elongated jaws and in a manner that locates a portion of the workpiece outside of the jaws so that an elongated portion of the workpiece is available for inspection by capacitive sensors. The sensors are located adjacent at least one surface of the elongated portion of the workpiece, the sensor and workpiece forming an electrical capacitor when appropriate potentials are applied to the sensor and workpiece. The sensors are now moved along the surface in the elongated direction of the workpiece to detect chatter marks on the surface.

Claims

1. A method of measuring chatter on at least one surface of a rolled metal sheet or plate having substantial length and width dimensions comprising:

flattening gross buckle or curvature that might be in the sheet or plate;

maintaining the flatness of the sheet or plate;

locating at least one sensor adjacent a surface of the sheet or plate and without contacting the surface, said sensor and sheet or plate forming an electrical capacitor;

applying an electrical potential across said capacitor;

moving said sensor along and parallel to the sheet or plate in a precision plane;

sampling sensor output at a rate that produces multiple data samples of measurement per interval of sensor travel distance; and

differentiating said data samples twice to arrive at a number for the curvature of the surface of each interval travelled by the sensor.

2. The method of claim 1 including:

using sensor measurements to quantify marks on the workpiece surface that are the result of coolants unevenly applied to the rolls of a rolling mill employed in producing the workpiece.

3. The method of claim 1 including using a cluster of side-by-side sensors to increase the resolution of the sensing process.

4. A method of measuring rolling mill chatter marks on a surface of a relatively large metal workpiece comprising:

flattening gross buckle or curvature in said workpiece in a manner that locates an exposed portion of the large workpiece in a position for inspection by at least one sensor capable of sensing chatter marks on the surface of said exposed portion facing the sensor;

maintaining the flatness of said workpiece;

locating a sensor adjacent said exposed portion and without contacting the surface of the same, said sensor and workpiece forming an electrical capacitor;

applying an electrical potential across said capacitor; and

moving said sensor in a precision plane along and parallel to the surface of the exposed portion in an elongated direction of the workpiece to detect chatter marks on the said surface.

5. The method of claim 4 including:

locating the sensors in a support structure; and

providing said structure with a pivoting capability that permits the sensors to adjust to the position of the elongated portion of workpiece available for inspection.

6. Apparatus for sensing the presence of chatter marks on the surface of elongated and relatively wide rolled metal workpieces comprising:

means for clamping an elongated, wide workpiece in an elongated clamping device to remove gross buckle or curvature in the workpiece, with an elongated portion of the workpiece extending from said clamping means for inspection by a sensor;

means for mounting a sensor adjacent the elongated portion of said workpiece extending from the clamping device;

said sensor and workpiece forming an electrical capacitor;

a precision plane located adjacent the elongated portion of the workpiece;

means for moving the sensor along said precision plane and along the workpiece portion extending from the clamping means; and

an operational amplifier electrically connected to receive and sample the output of the sensor during intervals of travel distance of the sensor and to differentiate sample data in a manner providing a number indicative of the curvature of each surface interval travelled.