Attached ferromagnetic coercimeter

 

The invention relates to the field of magnetic measurements of the coercive force of local areas of the product. Proposed attached ferromagnetic coercimeter containing U-shaped core with magnetizing and demagnetizing windings of the indicator element in the form of ferromagnetic cumulative counter and compares the device. The indicator element is designed in the form of two ferromagnetic cumulative counters with accumulation factors, changing in opposite directions of the elements mounted on the side bars of the U-shaped core, the outputs of which are connected with the input of the comparing device, and magnetizing, she demagnetizing coil is installed on the middle rod. The measured value is determined by the frequency difference between the ferromagnetic cumulative counters in comparing the device, which improves the measurement accuracy and sensitivity. 1 Il.

The invention relates to magnetic measurements, and can be used to measure the coercive force of local areas of the product.

Known side ferromagnetic coercimeter consisting of terrasond and attached to the solenoid [1]. This device poses the te layer-by-layer quality control of heat treatment. The measurement process includes a pre-magnetization and smooth demagnetization. For measure the coercive force is accepted, the degaussing current, in which the useful signal in the measuring winding terrasond equal to zero.

The disadvantage of this side of the ferromagnetic coercimeter is that the indicator winding terrasond electromotive force is not zero in the absence of an external constant magnetic field, which leads to additional error.

Known side ferromagnetic coercimeter containing terrasond on the U-shaped core is used as the indicator element, the magnetizing and demagnetizing winding located on the jumpers core terrasond [2]. U-shaped core terrasond and product form a closed magnetic circuit. On the rods core terrasond are winding through which the terminals periodically with a frequency doubled brought to saturation. On the jumpers placed the measuring winding - she magnetizing, which highlighted the useful signal by using a flat schema.

The disadvantage attached ferromagnetic coercimeter is that the value electoratewise force, reduces the measurement accuracy.

The prototype of the invention is attached ferromagnetic coercimeter [3] containing U-shaped core with magnetizing and demagnetizing winding, the indicator element in the form of at least one ferromagnetic cumulative counter and compares the device.

When the product is not magnetized, the frequency of the output signal of the indicator element takes a value of f1that after magnetization reaches a value of f2. Using a degaussing current adjusted value of the output frequency f2to the initial value f1at the output of the comparing device, the frequency is zero, the current razmahivanie if this is taken as a measure of the coercive force.

The disadvantage of the prototype is the lack of settings on the signal interference caused by the gap between the ends of the U-shaped core and products, which reduces the accuracy and sensitivity of measurements.

The present invention allows to obtain a new technical effect of improving the measurement accuracy and sensitivity.

This technical effect is achieved by the fact that the indicator element ferromagnetic cumulative counter consists of two ferromagnetic cumulative counters with the cylinder which are connected with the input of the comparing device, and magnetizing, she demagnetizing coil is installed on the middle rod.

The drawing shows a schematic side ferromagnetic coercimeter.

Attached ferromagnetic coercimeter contains a U-shaped core 1 placed thereon magnetizing and demagnetizing winding 2 and indicator elements 3 and 4, in the form of two ferromagnetic cumulative counters, with accumulation factors of opposite signs, located on the side rods of the core 1. The outputs of the indicator elements is connected to the input of the comparing device 5, and U-shaped core 1 and article 6 form a closed magnetic circuit.

Attached ferromagnetic coercimeter works as follows.

The gap between the ends of the core 1 and 6 product significantly affects the accuracy of the measurement and depends on the uniformity touch the ends of the U-shaped core 1 with the surface of the test object 6.

The magnetizing winding 2 is de-energized and the degaussing current is equal to zero, the indicator elements 3 and 4 have some originally established, the values of the coefficients of accumulation1and K2with indicator elements 3 and 4 are removed signals whose frequency is equal compliance and articles 6 different the value of f1and f2not equal among themselves. By setting the gap between the core 1 and article 6 achieve equality of these frequencies and as a result, the output signal of the comparison circuit is equal to zero

Article 6 of the part is subjected to application of short pulse current flowing through the magnetizing winding 2. At this time, the power supply and signal recording cumulative counters indicator elements 3 and 4 are disabled.

After magnetizing the residual induction of the product 6 creates a flux in the closed magnetic circuit through the core 1, the coefficients of accumulation of indicator elements 3 and 4 take the values of

K’1=K1-n and K’2=K2+n

where n is an integer.

Depending on the direction of the magnetic flux in the magnetic circuit core 1 and article 6 (which depends on the direction of the magnetizing field and the operation of the device is not affected) the integer n characterizing the change accumulation, has the sign + or -. The frequency of the output signal of the indicator elements 3 and 4 become respectively equal to

Thus, the frequency of the output signal of the indicator element 3 becomes larger by the value off, and the frequency of the recording.

The frequency difference indicator elements 3 and 4 from the output comparing device 5 is proportional to the magnitude of the residual induction of the tested part 6:

Since the coefficients of accumulation of indicator elements 3 and 4 are changed in opposite directions, the frequency differencef becomes twice that improves the sensitivity compared to the prototype.

For measuring the coercive force of the product 6 in the magnetizing winding 2 serves a current of reverse polarity.

If you increase the DC demagnetization in magnetic circuit core 1 and article 6 creates a magnetic flux in opposite directions. The coefficients of accumulation of indicator elements 3 and 4 are changed, closer to the original meaning. Accordingly, the frequency at the output of the comparison circuit.

The degaussing current value at which the frequency of the output signal of the comparison circuit takes the value of zero is taken as a measure of the coercive force.

The use of the invention allows the quality control of ferromagnetic products by two parameters: the magnetic induction and the coercive force. This increases the accuracy of reading of Semenov 3 and 4 in opposite directions makes it possible to increase the sensitivity of the measured parameters, accordingly, to increase the limits of measurement of the magnetic induction and the coercive force of the product 6.

Sources of information

1. The journal of nondestructive testing", 1972, No. 6, S. 21.

2. USSR author's certificate No. 407252, CL G 01 R 33/02, 09.07.71.

3. USSR author's certificate No. 834635, CL G 01 R 33/12 (prototype).

Claims

Attached ferromagnetic coercimeter containing U-shaped core with magnetizing and demagnetizing winding, the indicator element in the form of at least one ferromagnetic cumulative counter and compares the device, wherein the indicator element is designed in the form of two ferromagnetic cumulative counters with accumulation factors of opposite signs, mounted on the side bars of the U-shaped core, the outputs of which are connected with the input of the comparing device, and magnetizing, she demagnetizing coil is installed on the middle rod.

 

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