Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
  • G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
  • G01B7/06—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness
  • G01B7/10—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness using magnetic means, e.g. by measuring change of reluctance
  • G01B7/105—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness using magnetic means, e.g. by measuring change of reluctance for measuring thickness of coating
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
  • G01B7/34—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring roughness or irregularity of surfaces

Definitions

• the field of the invention is electricity, measuring and testing wherein a layer or layered material thickness is measured using a magnetic field to test the material.
• the present invention is parti ⁇ cularly concerned with the measurement of the thickness of nonmagnetic coatings or layers on magnetic base materials.
• U.S. Patent 2,469,476 of Sellers discloses an instrument for measuring the thickness of nonmagnetic coatings on a ferrous base and the patent also dis- closes that it is possible to use the instrument for measuring the irregularities in the surface of a machined ferrous material.
• an adjustable bar. magnet bridge is pivoted between the legs of a U-shaped magnet. The limbs of the U-shaped magnet are placed on the surface to be measured.
• the pivoted bar magnet has an indicator attached thereto and is spring biased so that changes in the magnetic flux of the U-shaped magnet indicate the layer thick ⁇ ness or roughness.
• U. S. Patent 2,625,585 makes use of the principle that forces necessary to disengage a magnet from a workpiece vary in- inverse proportion to the thickness of the non ⁇ magnetic plating or coating disposed upon the magnetic base surface.
• U.S. Patent 2,903,645 makes use of this same principle but in a more complex instrument.
• U.S. Patent 3,521,160 is representative of a series of patents of Nix et al which show magnetic thickness gauges using a magnet mounted on the end of a balanced rotatable arm to which a dial is coupled over a spring. The dial is turned until the increasing tension of the spring breaks the magnetic contact and the thickness is read directly from the dial.
• the comparator has the following elements:
• the comparator is used for making measure ⁇ ments by placing a first or reference pole of the rod magnet in contact with a reference ferromagnetic base material.
• the second or measuring pole of the rod magnet is placed in contact with the coated or roughened ferromagnetic surface to be measured. Both slides or spacers are moved to the extremities of the measuring and reference poles, respectively, and then moved together by hand or other means.
• An indication of the center or middle position of the rod magnet is provided and deviations from this center point by the coincidence of the slides is an indication of the
• OMPI thickness and/or roughness of the surface being measured are measured.
• Fig. 1 is a side view in partial cross- section of the coating thickness and surface roughness comparator of the present invention as used with a reference surface and a coated surface;
• Fig. 2 is a bottom plan view of Fig. 1; and Fig. 3 is a cross-sectional view of Fig. 1 along the line III-III.
• the comparator is shown having a housing or casing 2 with a scale 4 thereon.
• the scale 4 is calibrated with a plus scale on one side of the center or middle of the permanent rod magnet 6 and " a minus scale on the other side of the middle of the rod magnet.
• the rod magnet 6 is supported in holes 8,10 at the ends of the housing.
• the housing 2 is composed of a nonmagnetic material and the holes 8,10 can hold the rod magnet 6 securely by friction so that the middle of the rod' magnet is in register with the zero indication of the scale 4.
• Nonmagnetic slides or spacers 12, 14 support a ferromagnetic rod 16 substantially parallel to the rod 6.
• the ferromagnetic rod 16 is preferably a cold
• An adjustable spacer 18 is releasably fixed to the housing 2 by a screw 20.
• An uncoated steel plate 24 is positioned adjacent a reference pole 22 (one end of the rod 6) and a measuring pole 26 (the other end of the rod 6) is placed against a coating 28 on a steel plate 30.
• the spacer 18 is provided with a V-notch on one end and is adjustable so as to accom- odate a rod (not shown) rather than the plate 24 if desired.
• the uncoated steel plate 24 (or a rod) is releasably fixed at the end of the device by an elastic member or spring 17.
• the spring 17 passes over two arms 39 which extend from either side of the housing 2.
• the arms 39 are provided with grooves so as to securely receive the ends of the • spring 17. In this way, the plate 24 is releasably urged against the end of the rod magnet 6 and the end of the adjustable spacer 18.
• the adjustable spacer 18 is shown with an adjustment slot 19 so as to permit the spacer 18 to be moved relative to the housing when the plate 24 is replaced by a rod (not shown) .
• the slider 14 is shown in Fig. 3 with two notches 32, 34 engaging a longitudinal opening 36 of the housing 2 and also supporting the rods 16 and 6 in the holes 38 and 40, respectively.
• the measuring pole 26 is placed adjacent to the coat ⁇ ing.
• the measuring pole 26 is preferably arranged perpendicularly relative to the coating to be measured.
• the reference pole 22 is prefer ⁇ ably arranged perpendicular to the standard plate 24.
• Both the base 30 and the standard plate 24 are preferably of the same ferromagnetic material, namely steel, and preferably are of the same thickness or roughness.
• the base 30 (and the coating to be measured) may also be arranged either horizontally or vertically with the measuring pole 26 arranged at an angle of 45° relative to the base 30. In this way, any effect of gravity on the accuracy of the device is minimized by maintaining the device at an angle of 45° to the horizon.
• the rod 6 preferably extends sufficiently beyond the ends of the housing so that the device may be readily oriented at the angle of 45° with the end of the rod 6 in contact with the coating to be measured.
• the sliders 12 and 14. are moved outwardly toward the measuring pole 26 and the refer ⁇ ence pole 22, respectively, and the sliders are then pushed together until they coincide.
• the measuring pole Due to the coating 28, the measuring pole is not attracted to the base 30 to the same extent as the reference pole 22 is attracted to the standard plate 24.
• This magnetic attraction of the pole 26 to the base 30 varies inversely according to the thickness of the coating 28 and as a result of the reduced magnetic
• the device according to the present invention may also be operated in other manners.
• the standard plate 24 may be replaced by a standard plate having a known coating thickness and as a result thicker coatings can be measured at the measuring pole 26 without exceeding the range of the scale 4.
• the reference pole 22 is first placed preferably at an angle of 45° to the horizon and contacts a standard plate (not shown) which is arranged either horizontally or vertically. There is no plate provided at the measuring pole 26.
• the reference pole 22 is placed adjacent to and preferably at an angle of 45° with respect to the base 30 having a nonmagnetic coating 28 and again there is no plate at the measuring pole 26.
• the sliders 12 and 14 are moved to the measuring pole 26 and to the reference pole 22, respectively, and they are then pushed together until they coincide and a second reading to the left of zero on the scale 4 is recorded.
• the difference between the first reading recorded and the second reading is representative of the thickness of the coating 28.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
• Length-Measuring Instruments Using Mechanical Means (AREA)
• A Measuring Device Byusing Mechanical Method (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=23246746

Family Applications (1)

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Family Cites Families (5)

• 1982
  • 1982-11-12 EP EP19830900131 patent/EP0093772A1/de not_active Withdrawn
  • 1982-11-12 WO PCT/US1982/001602 patent/WO1983001833A1/en active Application Filing
  • 1982-11-12 DE DE19823249201 patent/DE3249201T1/de not_active Withdrawn

Non-Patent Citations (1)

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