SU1281369A1 - Method of relieving residual strain by vibration - Google Patents

Abstract

The invention relates to the field of mechanical engineering, relates to the removal of residual stresses from the structures in metal structures after welding, heat treatment or casting, and allows to achieve maximum stability of the geometry and dimensions of products during operation by objectively determining the end of the vibration removal process. residual stresses. To do this, they continuously measure stresses at points with extreme values of tensile and compressive stresses, then summarize the results of measurements a module and when the minimum value of the sum of the results of measurements npeKi-aina- handling dissolved. The stopping time of the processing is recorded when the sum of the results of measurements for their increase is bent. 2 ill., 1 tab. and iS

Description

The invention relates to the field of residual stresses formed in metal constructions after welding, heat treatment or casting, and is designed to optimally establish the cycle time for vibration processing of hardened and cast structures of buildings, running gear parts and other components. products, where the relaxation of residual stresses over time can cause deformation.

The aim of the invention is to increase the geometric and dimensional accuracy in the operation of parts by objectively determining the optimal duration of the process.

Figure 1 shows a device that implements the method, side view; Fig 2, the same, top view.

Item 1 with magnetoelastic sensors 2 by means of clamps 3 and gaskets 4 is mounted on the top plate 5, equipped with a vibrator 6, the top plate 5 by means of springs 7 is elastically mounted on the bottom plate 8 with vibration supports 9,

Vibration treatment is carried out to relieve residual stresses on parts such as crankcase,

By serial technology, these parts undergo tempering to relieve stresses after preliminary machining and welding casting defects to obtain dimensional stability.

after final machining. Vibration processing in order to replace a long and expensive thermal tempering process with a simpler and more economical - vibration one. The residual voltages in the parts are measured simultaneously in four points around the perimeter of the flange of the parts with the INI-1 and MF-80M devices. Instruments use the effect of changing the magnetic permeability of a material when the magnitude of internal stresses changes and allows non-destructive testing of the level of stresses in the parts directly during the vibration treatment process.

Vibration processing of parts is carried out on a vibration table, which allows | Process parts up to 600 kg and

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smoothly change the frequency of vibration from 10 to 200 Hz,

Item 1 is installed through the pads 4 on the top plate 5 of the vibrator 5 of the stand and is fixed with the clamps 3. According to the results of the measurement of residual stresses, the locations of the extreme values of the residual compressive and expansion stresses are determined and 10 magnetoelastic sensors of the device are installed in these places MF-80M,

With the chosen clamping scheme, the resonant frequency of the parts is 45-50 Hz. Vibration processing is performed at this frequency. The change in the level of residual stresses at selected points during the processing is recorded by the readings of the MF-80M device. The strength of the force field H is determined as the average value of the residual stresses, cf.

;, (WITH

defined in detail.

25

H And,

РN

The number of measurement points N in the formula is a constant value for all measurements on this part. Therefore, for the convenience of calculating the strength of the force field of the part, at different times, only the total voltage at the measurement points 21 (G;,

When calculating Z (b;), the extreme values of the tensile and compressive stresses (maximum and minimum) are decisive, since during vibratory processing, the peak (maximum) values of residual stresses decrease most intensely, and places with a minimum value of residual stresses. Voltage values are summed modulo.

The results of measuring the level of residual stresses (kgf) at different points in time during vibration treatment of a crankcase part are shown in the table.

As can be seen from the table, the level of residual stresses at the control points of a part, the crankcase, during vibration processing, varies differently not only in magnitude but also in time.

At the first point, the residual stresses decrease from 32 kg / mm to 15 kg / mm, t, e. to a minimum through

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after the start of processing. If a

p pr de no po

at this time, to stop processing, according to a known method, the total stress at four points of the part will be 50 kg / mm.

At the second point, the residual stresses decrease from 12 to 8 kg / mm, i.e. to a minimum after 15 minutes of processing, and the total voltage is 54 kg / mm,

Summing up the magnitude of the residual stresses in the parts at different points in time makes it possible to determine the optimal process time — 20 minutes, when the total stress in the part is minimum — 46 kg / mm. As the process time increases and its decrease leads to an increase in the strength of the force floor in the product.

Therefore, stresses must be measured at several points, at the same time comparing their value modulo, and finish processing when this amount becomes minimal,

Z: (0; 18 + P + (-11) + (-6) 46

O

five

Thus, it follows that the control of the vibration treatment by the proposed method allows to accurately determine the end of the process and thereby obtain the minimum value of the strength of the force field in the product.

Claims (1)

Invention Formula The method of vibratory removal of residual stresses, in which the workpiece is mounted on a shaker, is subjected to - vibration impact and in the process of vibration stress relief, they are continuously measured by a non-destructive method, characterized in that, in order to improve the geometrical and dimensional accuracy at parts, residual stresses are measured at points with extreme values of tensile and compressive stresses, the measurement results are summed modulo 5, and the process of vibration removal April zheny terminated when the minimum measurement value amount. 0 9uz.1 ag.g