DE2416852A1 - DEVICE FOR THE CONTINUOUS TESTING AND EVALUATION OF STEEL PIPES WITH NON-FERROMAGNETIC LAYERS - Google Patents

Description

Device for continuous testing and evaluation of steel pipes with non-ferromagnetic Layers __

For measuring non-magnetic layers on ferromagnetic layers Document, e.g. B · for measuring plastic layers on metallic pipes, various devices are known.

Such a device is, for example, the device measuring according to the capacitive principle, which is mainly used for non-contact measurement of strips. In this system, the measuring element is viewed as two capacitors connected in series, with one dielectric being formed by the material to be measured. * If the thickness is to be measured over larger areas, several capacitors must be connected in parallel. This solution then shows the average value, if the thickness is almost constant on the measured area, this value can therefore be considered sufficiently. In the opposite case it can happen that the indicating instrument shows the true thickness. A very big disadvantage of this system is that the displayed values can be influenced to a large extent by parameter changes.

There are also devices known that the reflection signals when the object to be measured is exposed to sound Take advantage of ultrasound. The ultrasound is already from the surface of the material to be measured and to the Part after it has penetrated the layer to be measured, from the opposite side of the same reflected · The characters obtained arrive, appropriately shaped, for display · Via the known Speed of propagation of ultrasound and

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the distance of the transmitter from the surface of the material to be measured, the thickness of the layer to be measured can also be determined.

Devices measuring with permanent magnets are also known. The Induction strength measuring devices found. The two windings present in a measuring head are retained their excitation from a Vienna bridge circuit · The amplified output signal of the bridge circuit, the Layer thickness signal is displayed.

In a further method, the phase angle between the generator voltage and the output signal is used as Measure for the layer thickness used, with permeability-related display errors due to suitable dimensioning can be reduced within certain limits. But here, too, it is a calibration to the basic material at hand necessary.

The invention is now based on the object of eliminating the disadvantages mentioned to create a measuring device and in the formation of a simple, cheap production of a device operated by the mains power, which is made independent of the pressure Measuring heads beeitzt, in which the signal formed by means of an ordinary basic instrument with direct Reading of the layer thickness can be carried out.

Accordingly, the invention is a layer die measuring system for meosing your non-ferromagnetic layer on a ferromagnetic base on which

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a measuring pulse excited by eiötw Qfj & erator (1) "(2) on the inductivity change, one of the layer thickness piopöUtionaXea Signa.! produced »The one by one

must be one high ifweisfti · For this ÖJPttM became a rectangle generator with ermitteXter Clock frequency [«e» ?! built up and then with a fixation into a harmonic-poor sinusoidal oscillation

The fe0ia € n in ^ eliie gesQüaHieten P * ipiairspuXen (3) were J? 4t dienero Bj? 3? E $ er & ignaX beauf aohXagt «Depending on © Xe ^ j? DiNgnei! I06h ^ r iTei? 0i; iwraung arises in the two GefeäeinandeigeefoliaXt et en secondary coils (4) a ^ McÖÄiciÄeifeiöal · By means of a Abgleiohvorrich-, WeX <i | e each «one eriiBär and secondary coil ent« · -.

^ m according to the material ^^ resembles # Vm a precisely fixable *

© ή JsM ^ e ^ ß ^ a aee Heßajmlensystems »u guarantee, if the gap it the coil core roit a ^^ · Soaiit is also the wear with continuous measuring processes not j) s, 0 in the secondary coils (4) _the vbn interfering signals, Cjb ^ rwaves etc. are, apart from these still cleaned, contaminated layer the kensignal is in a (f) ^: from the interfering signals, * which separate the hess result oil he filter (5), It has to be very Uf-built, only allows signals of the appropriate frequency to pass through *

filtered ^ fe SV & ßsignal, tob in the size of the amplitude the splint; dicIce contains »must be reinforced for further processing. This is done with a

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stabilized normal AC voltage amplifier with adaptation (6). It is thus possible to use the measurement signal multiple times. The amplifier (6) works reaction-free and does not affect the measuring system.

The multiple use of the measurement signal brings several Be quick and in a hurry. Once you can do the amplified Signal (7) rectified for display by means of a simple measuring instrument calibrated to the layer thickness (8), bring. It is therefore possible to read off the layer thickness directly on the instrument (8) The amplified signal can also be used to control what is known as an automatic protection system (9) will.

This offers possibilities for the automation of the layer thickness measuring system. It is possible with that one To counteract the destruction of the measuring head and to prevent it from colliding with the unsintered pipe. Likewise, a corresponding combination of threshold switches that are set at the output of the Amplifier unit are connected, the minimum and maximum of the layer thickness optically and acoustically evaluated.

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Claims (1)

Claims ^ Device for measuring and evaluating shift dioks nonferromagnetic media on ferromagnetic media Documents, characterized in that by means of single-pole magneto-inductive buttons, wherein those of the thickness of the non-ferromagnetic Shift-dependent detuning of the mutually connected Coils (3 + 4) creates a voltage and after filtering (5), amplification (6) and In-phase rectification / 7) is brought to the display that at a determined frequency a sinusoidal voltage generated by a square wave generator (1) with subsequent filters (5) in Applied, whereby the influence of the radius of the pipe is largely excluded, and thus a calibratable display (8) is achieved for almost all pipe dimensions and that läeßkopf and adjustment coil from two series-connected Primary coils (3) and two oppositely connected Secondary coils (4) consists 2 «Device according to claim 1, characterized in that that the square-wave generator (1) emits a signal · high constancy, which in the PiIterschaltung (5) in a highly constant sine wave is converted and has a certain frequency 3 · Device according to claim 1, characterized in that "; ■ that the measuring coil, consisting of two windings with a primary (3) and a secondary coil (4) * matched by moving it on the core of the Abgleiohspule will. 5 09818/0685 Device according to claim ■ 1Y characterized in that that the induced voltage in the oppositely connected Secondary coils by filtering (5) agile harmonics and stray frequencies is separated and further processed Device according to claim 1 to 4, characterized in that that the amplified measuring signal is used to control the automatic protection (9), so that the sensitive measuring head (2> when touching of the uncoated pipe is automatically lifted off from this, or becomes a pipe when the layer thickness is below the minimum value, displayed and sorted out, for this purpose several measuring heads (2), which are evenly distributed on the pipe circumference on a rotatable ring and thereby each Place of the pipe is accessible, used. 509818/0685