摘要:
An eddy current thickness probe for measuring the thickness of a weakly ferromagnetic material layer on a ferromagnetic base is provided with an essentially constant magnetic field bias. The magnetic field bias is of sufficient strength to substantially saturate ferromagnetic constituents in the weakly ferromagnetic layer. This eliminates any effects of changes in permeability of the weakly ferromagnetic layer which would otherwise impair the operation of an eddy current thickness gauge.
摘要:
A system (10) for determining the thickness of a magnetic flux conductive clad material over a magnetic flux conductive base material of different permeability applies on alternating voltage (96) to the primary winding (52) of an incomplete core-type transformer (54). The secondary winding (40) voltage to primary winding (52) voltage ratio is determined with the material being clad-thickness measured (56) completing the incomplete core (54). The voltage ratio is a nondestructive measurement of the thickness (64) of the clad material. The preferred embodiment applies a constant voltage alternating voltage power source (18) to the primary winding (52). This obviates the need to determine the ratio of voltages. The secondary winding (40) voltage is a direct nondestructive measurement of the thickness (64) of the clad material. By reference to a particular clad material-base material chart, the clad thickness is read from the scale adjacent the intersection of the voltage induced in secondary winding (40) and the curve (78,80,82,84,86,88,90,92,94) representing the composition of the clad material.
摘要:
A process for continuously testing the thickness of the enamel coating of electric wires, in which the wire, after enamelling, passes between a fixed and a movable measuring roller. The wire is wrapped around the fixed measuring roller such that its wrap-around angle has a value between 0 and 15 degrees and the fixed and movable measuring rollers are positioned relative to each other such that their respective planes of symmetry are vertically displaced by a value between 0.5 and 2 mm. Using the process according to the invention, the thickness of enamel applied to the wire can be kept constant to about 0.5 .mu.m.
摘要:
Apparatus for measuring, and indicating, the thickness of non-metallic coatings over a metallic surface, such as in sheathing of an electrical cable or similar structure, has a number of measuring heads, for example four, of electrical inductance type, spaced around the structure. A probe in each head has a profiled surface for presentation to the surface of the coating, the profile such as to offset any variation in inductance effects on the probe resulting from variation in diameter of the cable, without affecting the inductance effects of any variation in coating thickness. The measuring head is flexibly mounted and the signals from circuits associated with the probes are arranged to give visual indication of variation in coating thickness, and also any eccentricity. Particularly the indication can be a visual one representative of the cross section of the cable or the like.
摘要:
A measuring device incorporating a measuring nozzle through which a pressure medium is conveyed against the surface of an object to be measured, and a piston displaceable in a cylinder connected to the nozzle is controlled by the difference between the pressure acting at the nozzle and a reference pressure. Means are provided for varying the admittance of pressure fluid to inlets of said cylinder for displacing said piston towards the one end of said cylinder and for removing said measuring nozzle from the said object.
摘要:
This invention relates to a method and a device for measuring minima or maxima of the thickness of a dielectric layer on electric conductor means having prominent portions, wherein a measuring head scans the surface of the layer and minima or maxima of the thickness of the dielectric layer are detected, stored and indicated. Several minima or maxima may simultaneously be indicated and compared with each other whereby it is possible to determine the general position of the conductor means in a dielectric and absolute extremum values of the thickness.
摘要:
A method and device for measuring the thickness of layers, particularly of insulating layers on metallic parts. A measuring signal is produced corresponding to the thickness to be measured and this signal is compared with a comparing signal, balancing means being provided for adjusting both signals independently of the variations of the measuring signal by the measuring object, and means being provided for shifting one of said signals by a constant amount equal to the shift of said measuring signal upon removal of the measuring probe from the influencing range of a measuring object, reference balancing being thus possible with said measuring probe removed from the measuring object and said one signal shifted by said constant amount.