SU101044A1 - Instrument for determining the thickness of a non-magnetic material layer - Google Patents

Description

The known devices for determining the thickness of a nonmagnetic material layer, consisting of two magnets and a distance; Between neutral parts of the magnets of the DC-fed frame, they cannot be used directly to measure the thickness of the protective layers of concrete to the reinforcement, since these layers have relatively large electrical resistances.

In order to eliminate this drawback, the proposed device is made in the form of open-ended magnets without a magnetic core and without pole pieces (with a large magnetic dispersion).

FIG. 1 shows the scheme of the proposed device; in fig. 2 and 3 are the magnetic fields in the proposed device, which provides a measurement of the thickness of the protective layers of concrete to the reinforcement.

In the known devices, the rotatable frame is located between the magnets in an area where the field strength is zero when the magnets are identical.

Due to the use of magnetic conductor with pole tips, the point at which the resultant strength is zero is always in a certain place — in the center of the cylinder, which is formed by pole tips.

The proposed device consists of a rotating frame 1 fed by direct current, and two identical permanent magnets 2 and 3 that do not have a magnetic conductor and pole pieces (with a large magnetic dispersion).

The absence of magnetic conductors and pole lugs in the device is a prerequisite for ensuring high sensitivity and the possibility of using the device for measuring the thickness of a layer of concrete up to reinforcement.

FIG. Figures 2 and 3 show the magnetic field of the magnets 2 and 3. Line 4-4 and 5-5 are equipotential lines; At the point O of the intersection of these lines, the resultant field strength is zero. When approaching the ends of the magnets of iron 6 at a distance / picture changes: the point O with H3 is left straight: it moves along the line 4-4.

Thus, due to the absence of magnetic cores, the point O with zero intensity is not fixed, but moves along the line 4-4, depending on /.

The frame / is permeated by the difference of magnetic flux only npit one

value /. For all other values of x /, the difference between the flux flows does not penetrate the frame.

P o e. Lme t and z o brete n i

P;

h; yo1) for determination.: 1 thick

non-magnetic material

11 of the D 15uh magnets and locations;

-} oii mezhl. Neutral parts of the magnets of the turn of the frame, fed by a constant current, are connected with the fact that, in order to carry out large thicknesses, for example, the thickness of the protective Christmas trees of concrete to the reinforcement, it is made of 3 kind of open magnets magnetic conductor and without pole lugs) (with large magnet ;: scattering).

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FIG. 2

. 3

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