SU1206737A1 - Method of measuring coercive force of material of moving small-sized ferromagnetic articles - Google Patents

Description

The invention relates to magnetic measurements and can be used to determine the coercive force of small-sized products.

The purpose of the invention is to increase the measurement accuracy.

FIG. 1 shows the dependence of the magnetic flux P in the products on the size of the magnetic field acting on them And after magnetizing the products to saturation (A, B - for products of different geometrical sizes made of materials with the same coercive force Hj,; A, B - for products of the same geometrical dimensions

from materials with different coercive forces HC, IR; Fig ... 2 is a block diagram of the device that implements the proposed method.

The essence of the method is as follows.

For products with a large demagnetizing factor, made of magnetically soft materials (i.e., for almost any sufficiently short products made of carbon steel and cast iron), the induction (and magical flux) in the product is almost linearly dependent on the external demagnetizing field when it changes from O to the floor, equal to the coercive force of the material of the product; (Fig. l).

Necessary and a sufficient condition for this is the fulfillment

ratios

Iwg

 1, where N is razmag-

Bp - osniviVactions of the product factor, the exact induction of the material of the product in gauss, Hg is its coercive force in eststeeds. An analysis of the influence of various factors on the nature of the dependences of P and () shows that the integral nonlinearity of this function with Oi Н –Н- does not exceed 0.7% for

KvpNBp

-c- "10 and 0.2% for -fp- 20, for

Products from low-carbon and low-alloy steels are characterized by the following ranges of magnetic properties, depending, for example.

 “(H), and therefore does not depend on the demagnetizing factor and the geometric dimensions of the product under study. Therefore, variations in the geometric dimensions of the products do not reduce the accuracy of measurement of the coercive si of their material.

A device that implements the method contains a source of 1 magnetizing current and a magnetizing coil 2,

40 interconnected, the first account of the coil 3, installed. For the magnetizing coil 2 in the direction of the investigated products, the first detector 4, the first integrator

45 mountains 5 5 source 6 demagnetizing current, demagnetizing coil 7 and resistor 8, in series with each other included in the circuit of source 6 of demagnetizing current, second time

from heat treatment modes: In "5000-50 wiping coil 9, located

10,000 HS, Hj. 10-50 E. Then, for example, for cylindrical articles of such steels with a ratio of the length

eN8,

L to diameter d –g 5 ratio –n-

varies from about 30 to 12, which does not lead to the appearance of any significant nonlinearity at the center of the demagnetizing coil 7, the second detector is the second integrator 11, the computing unit 12 and the recorder 13, 55 14 designates the products under study, and 15 - directing chute

The first reading coil is decomposed in the path of movement of the products 14

dependences fn (H) with. The linearity of the PF (n) dependence is preserved in fairly wide limits even at. And O and Nd are therefore the only

The actual requirement for fields H and Hg is that, over the entire range of changes in the magnetic and geometric properties of the products under investigation, the magnitudes of these fields must be

corresponded to the linear region of dependence of PU 0 of the investigated products.

Thus, the results. Measurements of the magnetic flux Φ, with the field H acting on the product, and the flow when the product is affected by the field Hj lie on one straight line in the coordinated field. max i (N, RP). This direct equation has the form

  „(L- V ;; r,

Where, considering that 9 (And Oh, we find

 P, Hi-H, Pi

AND,

 WG WG

The result obtained does not depend on the slope of the dependence “

 “(H), and therefore does not depend on the demagnetizing factor and the geometric dimensions of the investigated product. Therefore, variations in the geometric dimensions of products do not reduce the accuracy of measuring the coercive force of their material.

A device that implements the method contains a source of 1 magnetizing current and a magnetizing coil 2,

interconnected, the first reading of the coil 3, mounted behind the magnetizing coil 2 in the direction of the investigated products, the first detector 4, the first integrator

 5 5 5 source of demagnetizing current, demagnetizing coil 7 and resistor 8, successively connected to each other in the circuit of source 6 of demagnetizing current, second second of the central plane of demagnetizing coil 7, second detector fO second integrator 11, computing unit 12 and recorder 13, Position 55 14 designates the investigated products, and position 15 denotes the supply trough.

The first reading coil is placed in the path of movement of the products 14.

between the magnetizing coil 2 and the demagnetizing coil 7 so that, in its location, the magnitude of the magnetic field acting on the product is zero. The demagnetizing coil .7 is located behind the first reading coil 3 in the direction of movement of the investigated products 14, the First detector 4 and the first

the integrator 5 is connected in series with the magnitude of the demagnetizing field H, but is also connected between the first reading; At this, the voltage from the resistor 8,

proportional to the value of the field, And is fed to the third input of the computing unit 1.2. Change in induction

The second detector 10 and the second integrator 11 are connected in series and connected between the second reading coil 9 and the second input of the computing unit 12, the output of which is connected to the recorder 13. The connection point of the demagnetizing KaTjOTKH 7 and the resistor 8 is connected to the third input of the computing unit 12,

The device works as follows.

Through the magnetizing coil 2, direct current is passed from the source of the magnetizing current, creating in the path of motion (e.g., free fall) of the products 14 a magnetic field in which the products 14 are magnetized but not frozen, and the area with the magnetizing field passes and passes through of its further movement the first reading

proportional to the magnitude of the floor And is fed to the third input of the computing unit 1.2. Change in induction

15 areas with a demagnetizing field H caused by the movement of the product 1A through this area, is converted by the second matching coil 9 into a two-field emf pulse, one of the half-waves

20 icoTOporo is passed by the second detector 10 to the second integrator 11 and integrated on it. The result of integrating this pulse, proportional to the magnitude of the magnetic flux P

25 in the product 14 when exposed to a demagnetizing field AND, is fed to the second input of the computing unit 12, which converts the incoming signals Pj to it,

30 9 and H by law

f

and (p -ip.

 output 1g

The resulting voltage and, j j coil 3, inducing a two-half-half in it, proportional to the coercive force pulse EMF. The first detector 4 of the material of the product under investigation and transmits to the first integrator 5, which is determined only by it, arrives at a unipolar pulse from this emf, the recorder 13.

the result of integrating which, proportional to the value of the residual magnetic flux P in the product under study, is fed to the first input of the computing unit 12, the Source 6 demagnetizing current and the demagnetizing coil 7 create in the path of further movement of the magnetized product 14 a region with a small

the magnitude of the demagnetizing field H, When this voltage from a resistor 8,

proportional to the magnitude of the floor And is fed to the third input of the computing unit 1.2. Change in induction

areas with a demagnetizing field H caused by the movement of product 1A through this area, is converted by the second matching coil 9 into a two-field emf pulse, one of the half-waves

icoTOporo is passed by the second detector 10 to the second integrator 11 and integrated on it. The result of integrating this pulse, proportional to the magnitude of the magnetic flux P

in product 14, when a demagnetizing field, AND, is applied to it, it enters the second input of the computing unit 12, which converts the incoming signals Pj to it,

9 and H according to the law

f

and (p -ip.

 output 1g

Erf

Jt

ts

Fu g

VNIIPI Order 8707/48 Circulation Circuit Subscription Branch Filial PPP Patent, g.Uzhhorod, ul.Proektna, 4

Claims (1)

METHOD FOR MEASURING THE COERCITIVE FORCE OF THE MATERIAL OF MOVING SMALL-SIZED FERROMAGNETIC PRODUCTS, which consists in the fact that the product is magnetized by a magnetic field, and then during the movement measure the magnitude of the magnetic flux in the product, which is different in that, in order to increase the accuracy value, magnetic flux in the product in areas with different magnetic fields; and the value of the coercive force _Hc article is determined from the relation _ύ <P H _r -M _{(F 2} ^N with --ςς · '·' where H, H ₂ - value of the magnetic field intensity in areas where measurements are performed; P,, F ₃ - magnetic flux values in the product. Fm »f 1 1206737