SU763704A1 - Device for measuring mechanical stresses - Google Patents

Description

la reference angles of rotation of the magnetic circuit.

The device for measuring mechanical stresses, forces and deformations consists of bipolar tips 1 of a flat permanent magnet 2,.

A flat permanent magnet is mounted in a bearing 3, which is rigidly fixed in the upper end of a part of a non-ferromagnetic element in such a manner that their axes coincide. Parts 4 and 5 of the non-ferromagnetic element are installed one below the other with a gap and spring loaded springs B and 7 symmetrically arranged.

A magnetoelastic sensor 8 is mounted in the gap between the parts of the non-ferromagnetic element. relative to the fixed arrow 13, rigidly fixed in a non-ferromagnetic element.

The device works as follows.

Permanent magnet 2 creates a working magnetic flux, closed through a controlled product and air gaps between pole pieces 1 and a controlled product. Part 5 of a non-ferromagnetic element mounted on the controlled product by a projection receives axial forces from the interaction of the poles with the controlled product through a magnetoelastic sensor 7 and Part 4 of a non-ferromagnetic element with a bearing 3.

The magnetoelastic sensor 8 converts this force into an electrical signal, which is fed through cable 9 to a recording device, Yu, which indicates the magnitude of the voltage. A permanent magnet and pole lugs rotated around the splicing axis contribute to a change in the readings of the recording device 10 (P1) and the uneven distribution of stresses in the part)

The registering device 10 marks the magnitude of the voltage variation, and the direction of the voltage reproduces a circular reference scale of the rotation angles of the permanent magnet 2 with poles 1 and arrow 13,

Ifa based on experiments, it was established that in order to obtain interacting poles it is necessary to introduce air gaps between the pole pieces 1 and the product under test, as well as between non-ferromagnetic elements to establish the operating range of the magnetoelastic sensor.

With a large gap, the interaction forces between the pole pieces and the item being monitored are reduced and the sensor sensitivity is reduced. With small gaps, it is difficult to transfer the sensor, and the performance of work with the sensor is reduced.

The following ratio of the clearances of the optimal compression of the magneto0 elastic sensor and the interacting poles of the magnetic circuit and the product under test is derived experimentally by calculation:

five

he.e.

where6 - air gap between the magnetic poles of the sensor;

air gap between non-ferromagnetic elements that

0 is confirmed by the following calculations.

NzshG- 5

force of interaction of poles of permanent magnets}

6 - magnetic induction in the air gap)

5 - the area of the pole.

0

Tension sensitivity of the product material (from ferromagnetic materials)

s ..

(one)

at.

five

whereDDD is the magnetostriction of the material

products at 3 00; & 00 magnetic induction with saturation of the material; f "- magneto permeability

0

material from where

re

2

B,

(2) 5pj I

(one)

Substituting formula (2) into the formula and taking B BOO, get

5000

whence it follows that F f (fu), i.e. The strength of the interaction of the poles of the permanent magnet with the induced poles in the product depends on the magnetic permeability of the material of the controlled product. Yao magnetic permeability in turn

& fU - 00

(3)

and going to increments roll

k2

(LN

Claims (2)

. and converting expression (3) to the form l 2 / uAci. Hence, the measured magnitude of the mechanical stress increment is directly proportional to the square root of the change in the force of the interaction of the poles and inversely proportional to the area of the interacting poles. It also follows from the above that the value of the geometric dimensions of a permanent magnet and its magnes for energy, as well as the installed air gaps must ensure magnetic saturation of the product material in the controlled area. Claims. 1. An apparatus for measuring mechanical stresses containing a magnetic core with a magnetizing element and a non-ferromagnetic element supported on the product under test, exc. In order to improve the accuracy of measuring the magnitude and direction of stresses, the magnetic circuit is made in the form of two L-shaped lugs mounted rotatably around a non-ferromagnetic element made of two parts located coaxially with the gap between them, in which the magnetoelastic The sensor, with the part of the non-ferromagnetic element resting on the test product, is installed with an output of pole tips of the value 1 ,. 4 are the heights of the gap between the parts of the non-ferromagnetic element, which are spring-loaded one to another. 2. The device according to claim 1, which is based on the fact that, in order to stabilize the process of measuring mechanical stresses, the magnetizing element is made in the form of a permanent magnet located on the part of the non-ferromagnetic element not supported on the product. 3. Device software PP. 1 and 2, characterized in that on the permanent magnet perpendicular to the axis of rotation of the magnetic circuit, the scale of the angles of rotation of the magnet is set relative to the arrow fixed in the non-ferromagnetic element. Isto; 4nmkk information taken into account during the examination .. 1. USSR author's certificate number 466411, cl. GO B 1/12, 1973. 2. Authors certificate of the USSR 321673, cl. G 01 B 7/2 |, 1969 (prototype). W 4v-V / 1) H h U