Dijeljenje znanja mjerenja debljine - mjerenje debljine premaza
Može nerazorno mjeriti debljinu nemagnetskih premaza (kao što su aluminij, krom, bakar, emajl, guma, boja itd.) na podlogama od magnetskih metala (kao što su čelik, željezo, legura i tvrdi magnetski čelik itd.) i nemagnetskim metalnim podlogama (kao što su bakar, aluminij, cink, kositar itd.) debljina neprovodljivih premaza (npr. caklina, guma, boja, plastika itd.). Mjerač debljine premaza ima karakteristike male pogreške mjerenja, visoke pouzdanosti, dobre stabilnosti i jednostavnog rada. To je instrument za ispitivanje za kontrolu i osiguravanje kvalitete proizvoda. polje detekcije.
When using the principle of magnetic induction, the thickness of the coating is measured by the size of the magnetic flux flowing into the ferromagnetic matrix from the probe through the non-ferromagnetic coating. The size of the corresponding magnetoresistance can also be measured to express the thickness of the coating. The thicker the coating, the greater the magnetoresistance and the smaller the magnetic flux. The thickness gauge using the principle of magnetic induction can in principle have the thickness of the non-magnetic conductive coating on the magnetic conductive substrate. Generally, the magnetic permeability of the substrate is required to be above 500. If the cladding material is also magnetic, the difference in permeability from the base material is required to be large enough (eg, nickel plating on steel). When the probe with the coil on the soft core is placed on the sample to be tested, the instrument automatically outputs the test current or test signal. Early products used a pointer-type meter to measure the magnitude of the induced electromotive force, and the instrument amplifies the signal and then indicates the thickness of the coating. In recent years, the circuit design has introduced new technologies such as frequency stabilization, phase locking, temperature compensation, etc., and uses magnetoresistance to modulate the measurement signal. The designed integrated circuit is also used, and the microcomputer is introduced, so that the measurement accuracy and reproducibility have been greatly improved (almost an order of magnitude). The modern magnetic induction thickness gauge has a resolution of 0.1um, an allowable error of 1 percent , and a range of 10mm.
The magnetic principle thickness gauge can be used to measure the paint layer on the steel surface, the protective layer of porcelain and enamel, the coating of plastic and rubber, the electroplating layer of various non-ferrous metals including nickel-chromium, and the various anti-corrosion coatings of chemical and petroleum industries. .
The high-frequency AC signal generates an electromagnetic field in the probe coil, and when the probe is close to the conductor, eddy currents are formed in it. The closer the probe is to the conductive substrate, the greater the eddy current and the greater the reflection impedance. This feedback action characterizes the distance between the probe and the conductive substrate, that is, the thickness of the non-conductive coating on the conductive substrate. Because these probes are designed to measure the thickness of coatings on non-ferromagnetic metal substrates, they are often referred to as non-magnetic probes. Non-magnetic probes use high-frequency materials as coil cores, such as platinum-nickel alloys or other new materials. Compared with the principle of magnetic induction, the main difference is that the probe is different, the frequency of the signal is different, and the size and scale relationship of the signal are different. Like the magnetic induction thickness gauge, the eddy current thickness gauge also achieves a high resolution of 0.1um, an allowable error of 1 percent , and a range of 10mm.
Mjerač debljine pomoću principa vrtložne struje može mjeriti premaze koji nisu vodiči na svim vodičima u načelu, kao što su boja na površini zrakoplovnih zrakoplova, vozila, kućanski aparati, vrata i prozori od aluminijske legure i drugi aluminijski proizvodi, plastični premazi i anodizirani film. Materijal za oblaganje ima određenu vodljivost, koja se također može mjeriti kalibracijom, ali omjer vodljivosti njih dvoje mora biti barem 3-5 puta različit (kao što je kromiranje na bakru). Iako je čelična matrica također električni vodič, prikladnije je koristiti magnetski princip za takve zadatke.
Način otklanjanja poteškoća
The faults of the coating thickness gauge for non-destructive testing mainly include unstable display value, large error, and no display value. The reasons for these failures are from the instrument itself, from the workpiece to be measured, and from the influence of the natural environment.
U nastavku je opisano kako otkloniti poteškoće s tim greškama.
Vrijednost prikaza je nestabilna
Razlog nestabilnog prikaza mjerača debljine premaza uglavnom je iz posebnosti materijala i strukture samog obratka, kao što je je li sam radni komad magnetski vodljiv materijal. Ako se radi o magnetski vodljivom materijalu, moramo odabrati mjerač debljine magnetskog premaza. , Ako je radni komad vodič, moramo odabrati mjerač debljine premaza vrtložne struje, a hrapavost površine i pričvrsti obratka također su razlozi zašto instrument ne pokazuje temperaturu. Hrapavost površine obratka je prevelika, a površinski priključci preveliki. mnogi. Glavna točka rješavanja problema je izgladiti radni komad s relativno velikom hrapavosti i ukloniti priključke, a zatim odabrati odgovarajući mjerač debljine premaza.
Previše je pogrešaka u rezultatima mjerenja
Ne prikazuj brojeve
Najjednostavniji razlog zašto mjerač debljine premaza ne prikazuje brojeve je provjera je li baterija potpuno napunjena i je li baterija potpuno napunjena, ako se utvrdi da mjerenje još uvijek ne prikazuje vrijednost.
