SU798185A1 - Method and device for control of structure vibrotreatment - Google Patents

Description

The invention relates to measurements * when removing residual stresses generated in metal structures after welding, heat treatment or casting, namely, to control the reduction of residual stresses by vibration of the main supporting structures of coordinate measuring machines and metal cutting machines, where the relaxation of residual stresses can cause deformation of structures during their operation.

Closest to the invention in technical essence and the achieved result is a control method used in the method of vibration aging to relieve residual stresses, and a device for implementing this method. The method consists in subjecting the part to mechanical excitation in the frequency range and recording the reaction of the part, i.e. resonant maximums of oscillations in this range. Such excitation is carried out repeatedly (in this case, the resonance maxima change their position on the frequency axis). The removal of residual stresses (i.e., the end of the vibration processing process) is completed. Then, when the position of these resonance maxima on the frequency scale stabilizes, and upon further excitation, the shift of the resonance maxima is absent. The method is based on the theory that a metal + having residual stresses is characterized by resonance maxima (the maximum falls on certain values. Frequencies) shifted on a frequency scale from the positions that these maxima occupy a metal free of stresses, or with their stable location, i.e. resonant maxima occupy erroneous positions in a stressed (unstable) metal - and actual positions in an unstressed (stable) metal / during vibration processing, resonant maxima are shifted from erroneous positions to real ·. During removal or stabilized voltages, the maxima no longer shift, since they occupy their actual (natural) positions.

So, observing the shift of the resonance maxima and registering the moment of stabilization of their position on the [frequency scale, they will learn about the end of the process of removing residual stresses ”

The method is carried out by a device containing a mechanical vibration vibrator mounted on a structure (part), a vibration sensor also installed on the structure (part) and connected through a filter to a recording device (for example, a two-coordinate recorder) that allows recording the vibration amplitude depending on the excitation frequency £ 1). ·

The known method has several drawbacks: if the workpiece is characterized by gentle resonance maxima, then setting the frequency corresponding to this maximum to 15 is rather difficult, inaccurate recording of these frequencies leads to errors in fixing the moment of stabilization of the positions of these frequencies on a frequency scale of 20, i.e. It does not allow to precisely determine the moment of the end of the technological process of vibration processing. In workshop conditions, this leads to an increase in time, __ associated both with the determination of the absence of a frequency shift of the resonance maxima and with the artificial and unjustified delay of the vibration processing process, which ultimately leads to a decrease in productivity- 30 labor.

In addition, in complex structures with a large number of degrees of freedom, it is likely that, for example, two resonance maxima are located very close to each other. When registering a curve, these two maxima can merge into one with the indicated method and device of registration. At the same time, the reliability of the information decreases, which leads to the same disadvantages indicated above.

The purpose of the invention is to increase the accuracy of recording the moment of completion of the vibration processing process and to reduce the vibration processing time.

This goal is achieved by measuring the real part of the amplitude-phase-frequency characteristic of the part, and removing and stabilizing it. The residual stress cycle fixes by stopping the displacement of the points ^ the transition of the measured curve through zero.

The device that allows to carry out the proposed method further comprises a force sensor with a filter and a phase-sensitive multiplier, and force and vibration sensors are connected through filters to the inputs of the phase-sensitive multiplier, the output of which 60 is connected to a recording device.

In FIG. 1 shows the recorded curves according to the known (A) and the proposed method (B); in Fig. 65 2 - a device for implementing the proposed method.

The device contains vibration exciter 1 of mechanical vibrations, force sensor 2, workpiece 3, vibration sensor 4, filters 5 and 6, which filter noise, interference and spurious signals, a phase-sensitive multiplier 7 and a recording device 8.

The device operates as follows.

The vibration exciter 1 of mechanical vibrations (it can be used as electromagnetic, electro-hydraulic, electrodynamic, mechanical unbalanced, cam vibrator) excites the workpiece (structure) 3. The frequency of the exciting force can vary. Frequency control of the vibrator is carried out by special control units (not shown in the drawing). These blocks can be an electric periodic voltage generator or a direct current electric drive, depending on the vibrator used. At the output · of the vibration exciter 1, a force sensor 2 is installed, which generates a signal proportional to the exciting force. This sensor performs direct (using a dynamometer) or indirect (for example, by magnetic field, by current strength, by working fluid pressure - depending on the type of vibrator) force conversion into an electrical signal. The force signal is written in the form F = Z F ^ s i π (i3Z.t), where F is the force, i is the number of the 'harmonic component,' ft is the excitation frequency. Enrichment of the signal with higher harmonics occurs due to the nonlinearity of the part, the principle of operation of the vibrator, noise, interference and spurious vibrations that characterize the workshop conditions. All frequencies distorting the information are filtered out by filter 5, the output of which is a signal F = F, (si Rf. T. The response of the part to excitation is measured in the form of vibration displacement of the part using the 4 vibration sensors and recorded as x = g xj si η (iS2t + q> J, where x is the amplitude of the vibration displacement, φ is the phase of the signal of the vibration displacement relative to the signal of the exciting force .. After filtering in the filter, b x = x <si n (ft t +

A typical response curve (vibration displacement) of a part to excitation in the frequency range (Fig. 1, A) is characterized by resonance maxima, which can be gentle, with a blunt apex (a, b, c, d). It is practically impossible to accurately determine the frequencies corresponding to such resonance maxima from such records.

In the proposed method, they measure not resonance maxima, but the real part of the amplitude-phase-frequency characteristic. The signals formed at the outputs of filters 5 and 6 are subjected to phase-sensitive multiplication in the multiplier 7. Moreover, the signal at its output is U ^ x / F ^ co.s qq. This signal is recorded in the recording device 8 as a function of the excitation frequency. This characteristic is x "cos = f (A) | (Fig. 1, c).

As is known from the theory of vibrations, at the places of resonance maxima, the phase shift between the exciting force ”by the vibrational displacement is the reliability of the information about the end of the vibration aging process, · accurately record the time of the end of the vibration aging process, i.e. removal and stabilization of residual stresses, thereby increasing labor productivity;

automate the registration of the moment of the end of removal and stabilization of residual stresses with the subsequent disconnection of the vibrators, i.e. fundamentally provide automation of the technological process of vibration aging.

Claims (2)

(54) THE METHOD OF CONTROL. THE PROCESS OF VIBR PROCESSING OF STRUCTURES TO DECREASE RESIDUAL VOLTAGES AND A DEVICE FOR ITS IMPLEMENTATION OF THE FACTOR OF FREQUENCIES. , also installed on the structure (parts) and through a filter connected to a recording device (for example, a two-coordinate recorder), which allows recording the amplitude of vibration depending The known method has a number of drawbacks: if the workpiece is characterized by gentle resonance maxima, then it is difficult to set the frequency corresponding to this maximum, inaccurate recording of these frequencies leads to errors when fixing the moment of stabilization of the positions of these frequencies on the frequency scale, t . It does not allow to set the exact time of the end of the vibro-processing process. Under shop conditions, this leads to an increase in time costs, associated both with the determination of the absence of frequency shifts of resonant maxima, and with artificial unjustified delay of the vibration treatment process, which ultimately leads to a decrease in labor productivity. In addition, in complex structures with a large number of degrees of freedom, it is probable that, for example, two resonant maxima are located very close to each other. By registering the curve, these two maxima can merge into one with the specified method and recording device. At the same time, the reliability of information decreases, which leads to the same disadvantages indicated above. The purpose of the invention is to improve the accuracy of recording the end of the vibration processing process and the reduction of the vibration processing time. This goal is achieved by measuring the real part of the amplitude-phase-frequency characteristic of a part, and removing and stabilizing residual voltages by fixing fOT by. stopping the displacement of the transition points of the measured zero-point curve. The device that allows the proposed method to be carried out additionally contains a force sensor with a filter and a phase-sensitive multiplier. FIG. 1 shows the recorded curves by the known (A) and the proposed method (B); on ig. 2 is a device for carrying out the proposed method. The device contains vibroStimulator 1 mechanical.vibration, datac 2 force, processed object 3, atchik 4 vi.bration, filters 5 and b, providing filtering noise, poeh and parasitic signals, phase-sensitive multiplier 7 and recording device 8, The device operates as follows. The vibration exciter 1 mechanical oscillations as it can be used. Electromagnetic, electro-hydraulic, electrodynamic, mechanical unbalance, cam vibrator)) excites the workpiece (design) 3. Often This excitation force may vary. The frequency control of the vibrator is carried out by special control units (not shown in the drawing). These units may be a periodic voltage generator or a direct current drive, depending on the vibrator used. At the output of the vibration exciter 1, a force sensor 2 is installed, which produces a signal proportional to the driving force. This sensor performs direct (using a dynamometer) or indirectly (for example, magnetic field, current strength, pressure of working fluid — depending on the type of vibrator; conversion of force into an electrical signal. The force signal is recorded as FZ (), where F is the force, i is the harmonic component number, L is the excitation frequency. the frequencies are filtered by filter 5, the output of which has a signal P P 51Pchü1. The part's response to excitation is measured as a part vibration using a vibration sensor 4 and recorded as XJ S i p (iat + Cf), where x is the amplitude of the vibration displacement. f is the phase of the vibration displacement signal relative to the excitation force signal. After filtering in filter b ("t + Cf) .. A typical response curve (vibration displacement of a part to excitation in the frequency range (Fig. 1, A) is characterized by resonant maxima, which can be gentle stupid top hydrochloric (a, b, c, d). It is practically impossible to accurately determine the frequencies corresponding to such resonant maxima from such records. In the proposed method, the measurement. Not the resonant maxima, but the real part of the amplitude-phase-frequency characteristic. The signals formed at the outputs of filters 5 and 6 are subject to phase-sensitive multiplication in multiplier 7. The signal at its output .s cf. This signal is recorded in the recorder, device 8 as a function of the excitation frequency. Such a characteristic is x F cos cf f (L) / (fig / c). As is known from the theory of oscillations, in the places of the resonant maxima of the phase shift between the exciting force, the vibratory displacement is equal to nine degrees, therefore, in these places the cos ф function vanishes. FIG. 1. The dotted line shows the correspondence between the resonant maxima and the places of the zero crossing points. Registration of zero transitions is easy. The simplicity of fixing these information points on the frequency scale allows us to automate the end of the vibration process with the auto-shutdown of vibrators that excite mechanical vibrations. The characteristic () f (Si) is the real part of the amplitude-phase-frequency characteristic. The described method of implementing the method of controlling the vibration treatment process shows that in any form of resonant maxima, it is possible to accurately fix the process of removing residual stresses of parts, which, in real shop conditions, increases productivity by reducing the total time of the vibrating process. The implementation of the proposed method allows you to accurately record the zero crossing points of the measured curve, thereby recording the moment of termination of the displacements of these points on the frequency scale, accurately register the details of the excitation, including closely spaced resonant frequencies, which generally increases the reliability of information about the end of the vibration process, accurately record the end time of the vibration process, i.e. the removal and stabilization of conventional stresses, thereby increasing labor productivity; Automate the registration of the moment of termination of the removal and stabilization of residual stresses with the subsequent disconnection of the vibrators, i.e. It is important to provide automation of the vibration process. Claim 1. A method of controlling the process of vibro-processing of structures to reduce residual stresses based on multiple vibratory excitation of the workpiece in the frequency range and simultaneous recording of the end of vibro-processing at the moment of stabilization of the frequency response of the part, characterized in that vibration processing and reduction of vibration processing time, determine the real part of the amplitude-phase-hour: the total characteristic of the part and finish vayut processing to end offset transition points amplitudnofazo-frequency characteristic through zero. 2. A device for implementing the method up to A.1, comprising a vibration exciter, a vibration sensor associated with the workpiece and connected to a filter and a recorder, which is distinct from that it additionally contains a force sensor, a second filter and a multiplier, the sensor The forces are connected in series through a second filter to the first input of a multiplier, the second input of which is connected to the output of the first filter, and the output to the recorder. Sources of information taken into account in the examination 1. US patent number 3741820, cl. 148-12.9 (from 21 d 1/04), 1973.