SU113473A1 - Instrument for determining the thickness of metal products from the surface - Google Patents

Description

The proposed device is intended to determine the thickness, thickness of the walls of metal products, such as pipes or sheet products, when direct determination of the wall thickness of the products is impossible or difficult. The device is made portable and gives sufficient accuracy of determination.

The peculiarity of the device is that it uses a highly sensitive vibrating alternating current galvanometer in the DC compensation circuit.

The drawing shows the electrical circuit of the device.

The device is based on measuring the voltage drop in the area of the metal product 1 between two potential contacts 2 and 3, which are pushed to the surface of the product, and current is supplied to this area 01 when two other current contacts 4 and 5 /

Potecial and current contacts are made spring-loaded to ensure they fit in the case of a curved product surface, with current contacts 4 and 5 connected to a 6-12 volt battery with a load resistance R and an ammeter 6 with a scale not lower than 10 a. The pins are single-line jumpers. The Electrical Circuit includes a potentiometer for current, with a highly sensitive vibrating galvanometer 7 and a vibrating interrupter 8 in the compensation circuit. The highly sensitive vibrating galvanometer 7 is a null pointer.

A polarized relay is applied as a circuit breaker in the compensation circuit; its excitation coil is supplied from an AC network with a voltage of 6-12 volts, used simultaneously to glow the light bulb 9 of a highly sensitive vibrating galvanometer 7. The constant current in the compensation circuit is converted into short pulses, the frequency which corresponds to the frequency

No. 113473

in AC. Vibrating galvanometer 7, tuned to resonance with the frequency in the AC mains, when these pulses are applied to it, works similarly to AC power. The sensitivity of the vibration galvanometer provides measurement of the wall thickness of the product with an accuracy of up to 6%.

The DC potentiometer consists of a calibrated resistance, connected in sequence to a 1.45 V dry cell circuit, a milliammeter 10 with a scale of 1 °, and a rheostat with resistance 3. At the ends of which a predetermined potential difference is created, compensating for a predetermined voltage drop between potential contacts 2 and 3 applied to the measured section of the metal product. This wall thickness of a metal product corresponds to a certain current strength, which is necessary to obtain a given voltage drop.

The relationship between the current strength and the wall thickness of the product is measured in the form of a graded curve previously on the corresponding samples. Using this graded curve, the wall thickness of the metal product is determined from the strength of the current indicated by the instrument.

Subject invention

A device for determining the thickness of metal products from the surface, characterized in that, in order to carry out the device with a PernO | Snym and giving a sufficiently accurate measurement accuracy for practice, it uses a highly sensitive vibrating AC galvanometer in a DC compensation circuit.