RU2763863C1 - Method for obtaining acoustic information for monitoring the technological process of surface alloying of ceramic and hard-alloyed tools - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: method for obtaining acoustic information for monitoring the technological process of surface alloying of ceramic and hard-alloyed tools consists in attaching a waveguide to the processed object, securing an oscillation sensor on the waveguide and processing information using a computer, recording the signal values in two frequency ranges until the signal amplitude drops to the level of background noise. Envelopes are then isolated, stretched in time. For a lower frequency range, the frequency of the carrier harmonic signal is selected within the lower part of the auditory perception range, and for the other range, the frequency of the carrier signal is selected in the higher frequency range. Frequency ranges wherein, according to the experimental data, the signal amplitude is subjected to the greatest changes with variation in the irradiation modes, are selected as frequency ranges. The new envelopes are used as modulating functions for the corresponding selected carrier signals. The modulated signals are separately amplified and directed to the headphones. The sensor is made in the form of an accelerometer with a frequency response characteristic covering the audible and ultrasonic frequency ranges.

EFFECT: reduction in the time for acquiring the technology of material processing and increase in the accuracy of setting the operating modes of the equipment.

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Description

The invention relates to the field of mechanical engineering, mainly to the heat treatment of metals and alloys in a vacuum chamber with electron beams in the form of short pulses, and can be used in a system for monitoring the resulting indicators of the process of heat treatment of surfaces, in particular, surface alloying of ceramic and hard alloy tools.

From the prior art there are known methods for outputting sound (vibration) information about phase transformations accompanying thermal exposure, which consists in the fact that the boundaries of phase transitions are determined using an acoustic emission sensor attached to the processed sample (1. RF Patent No. 2433190, IPC C21D 1/ 55, G01N 29/00, C21D 1/04, Bulletin No. 31, November 10, 2011, 2. Vyunenko, Yu.N. 3. Vorontsov V. B., Zhuravlev D. V. Relationship between the structure of acoustic emission signals during Al crystallization and the mechanism of solid formation phases from the melt // Bulletin of the Novgorod State University, No. 67. 2012. P. 8-13).

The disadvantage of these methods (analogues) is that they are designed for processing signals on a computer and displaying the results on a monitor for visual observation by the operator. However, this method assumes a high level of operator skill and the elaboration of decision-making algorithms regarding the controlled process occurring in the vacuum chamber. To create decision-making algorithms for numerous processes occurring in a vacuum chamber with a wide range of materials and modes, a preliminary cycle of research is required for each combination of the processed material and processing modes. Large time costs and high requirements for personnel qualifications lead to the fact that such methods are used only for scientific research. As a result, production quality control of processing processes in vacuum chambers is mainly carried out based on the results of the analysis of the characteristics of the resulting products. This disadvantage affects the quality of the products obtained and the time of selection of rational processing modes. But even with the selected modes, there is a random spread in the parameters of the supplied electron pulses that trigger the required reaction in samples in different volumes. Without online monitoring methods, this cannot be assessed and an adequate decision cannot be made on further actions (repeat processing, change technological modes). A significant disadvantage of these analogs is that due to the powerful electromagnetic interference created by the electron gun, the placement of measuring equipment and a computer in the immediate vicinity of the installation is associated with large interference and malfunctions of the measuring and computing equipment.

The closest in technical essence to the proposed invention is the method chosen as a prototype (in terms of the number of common essential features and the technical result achieved) for monitoring the electron-beam technology of surface alloying and heat treatment in vacuum chambers, which consists in attaching a waveguide in the form of a flexible wire to the object being processed, outside the vacuum chamber through a vacuum input, fixing the vibration sensor on the waveguide, processing information from the latter using a computer, an accelerometer with a frequency response covering the audible and ultrasonic frequency ranges is used as a vibration sensor, registration in time, starting from the moment of exposure to an electronic pulse of the beam, the current values of the signals coming from the accelerometer in two frequency ranges until the signal amplitude drops to the background noise level, the obtained time dependences of the effective values of si gnals with experimentally obtained reference dependencies, and based on the results of comparison, the sufficiency of the energy of the electron beam pulse or the results of the course of phase transformations are judged (Patent No. Method for monitoring electron-beam technology of surface alloying and heat treatment in vacuum chambers. Authors: Fedorov S.V., Kozochkin M.P. Published 28.08.2019, Bull. No. 25).

A disadvantage of the known method, including a technical problem, is that it is not intended for prompt informing the personnel servicing the vacuum chamber in production conditions. This well-known solution is intended for research work by highly qualified personnel who are well versed in the method of mathematical processing of vibration signals and can read graphic information on the monitor screen. With the accumulation of such information and its comparison with the results of the analysis of the qualitative indicators of the treated surfaces (for example, the uniformity of the coating with an alloying film, the depth of its penetration into the surface layer, the number of microcracks, etc.), a recommendation can be developed on rational processing modes (power of the electronic pulse, number of pulses, gaseous medium, etc.). An operator operating a production plant with an electron gun is not familiar with vibration diagnostics methods, but he has the usual skills of perceiving sound information. The human ear is able to perceive frequency and amplitude changes in an audio signal and its modulation. Comparing these changes with the results of determining the quality indicators of the surface layer of the processed parts, the operator can independently develop links between the parameters of organoleptic perception (loudness and modulation features in different frequency ranges, the ratio of signal amplitudes in different ranges) with the results of processing quality analysis. As a result, he will be able to independently assess the ongoing processes in the vacuum chamber and make decisions on correcting processing modes or re-irradiating the object. It's the same way an experienced driver judges the condition of an engine by changes in accompanying noise.

The claimed invention was based on the technical result - reducing the time for mastering the technology of processing new materials and increasing the accuracy of setting the operating modes of technological equipment that determine the parameters of electronic pulses and the effectiveness of their impact on the surface of the part, and improving the quality of products of electron beam processing due to timely correction of technological process.

The technical result is achieved by the fact that in the method for obtaining acoustic information for monitoring the technological process of surface alloying, which consists in attaching to the processed object a waveguide in the form of a flexible wire that extends through a vacuum input outside the vacuum chamber, fixing an oscillation sensor on the waveguide and processing information from the latter with using a computer, using an accelerometer as a vibration sensor with a frequency response covering the audible and ultrasonic frequency ranges (for example, the frequency range up to 100 kHz), recording in time, starting from the moment of exposure to an electron beam pulse, the current values of the signals coming from the accelerometer, in two frequency ranges until the signal amplitude falls to the background noise level, the envelopes of the obtained dependencies are isolated, which are stretched in time sufficient for auditory perception (for example, 50 or more times), forming new envelopes, for a lower frequency range, a quasi-harmonic signal carrier frequency is selected within the lower part of the auditory perception range (for example, in the range from 50 to 1000 Hz), and for another range, a quasi-harmonic signal carrier frequency is selected in a higher frequency range sufficient for a comfortable auditory difference with the selected low-frequency quasi-harmonic signal (for example, the carrier frequency of the signal is taken two or more times higher), as the frequency ranges in which the time dependences of the current values of the signals from the accelerometer are recorded, those frequency ranges are selected in which, according to experimental data, the signal amplitude undergoes the greatest changes at variations of irradiation modes, new envelopes are used as modulating functions for the corresponding selected carrier frequencies, the modulated signals are separately amplified and fed to a two-channel sound reproducing device to affect the right and left ears, the operator and accordingly.

The invention is illustrated by graphic images, which show:

in fig. 1 is a diagram of the installation of equipment that implements the proposed method for recording and analyzing vibration signals from an accelerometer that occur after an electronic pulse is applied and converting them into an audio signal that affects the operator's hearing organs;

in fig. 2 - an example of recording a vibration pulse that arose after applying an electronic pulse filtered in one of the frequency bands 10-19 kHz, and its envelope;

in fig. 3 is an example of a new envelope after stretching by 100 times and a view of the quasi-harmonic signal modulated by the new envelope;

in fig. 4 - an example of two quasi-harmonic signals generated in accordance with the proposed method, applied to the operator's hearing organs.

In accordance with the invention in FIG. 1 shows an example of a circuit that implements the hardware of the proposed method, where a waveguide 2, made of flexible wire, contacts the processed sample 1 and exits the vacuum chamber through a vacuum input, the opposite end of which is connected to the receiving plate 3, on which the accelerometer 4 is installed, the output of which connected to the preamplifier 5 connected to the analog amplifier 6, at the output of which an analog-to-digital converter (ADC) 7 is installed, the data of which is stored using a computer 8 for further processing in accordance with the claimed method and the formation of a two-channel acoustic display of the vibration signal, which is differentially supplied on headphones 9 with amplification and channel balancing devices used by the operator.

In FIG. 2 shows an example of a vibration signal 10 resulting from the application of an electronic pulse to the processed sample 1. The example shows the appearance of a pulse with a duration of 50 ms after filtering with a bandpass filter of 10-19 kHz. The envelope 11 for the signal 10, required in accordance with the claimed method, is built by sequentially calculating the effective (rms) amplitude values in short time intervals (in this case, 40 μs intervals were taken). The length of the time slices determines the details of the signal described by the envelope. A very detailed description does not make sense, because they are not distinguished by the human ear, a rough description loses essential details. The peak envelope can be built in the same way, where the maximum value is allocated for each time interval. However, practice shows that these envelope options are almost equidistant and do not improve the auditory perception.

In FIG. 3 shows the new envelope 12 after stretching by 100 times the initial envelope 11 and the quasi-harmonic signal 13 modulated by the new envelope 12. Inset 14 shows an enlarged portion of the quasi-harmonic signal modulated by the new envelope and a carrier signal at a constant frequency (70 Hz in this case).

In FIG. Figure 4 shows an example of two quasi-harmonic signals formed to sound vibration signals in two frequency ranges (two frequency ranges were chosen: 10-19 kHz and 19-40 kHz). The new envelopes modulate carrier signals at 70 Hz for the 10-19 kHz band and 250 Hz for the 19-40 kHz band. The volume of quasi-harmonic signals is equalized for their comfortable perception by the operator with simultaneous differentiated listening with different ears. The differential gain is set in advance based on experiments with typical process signals. With this approach, the maximum information content of each channel is ensured. Differential gain is done to balance signals in different channels. A signal that initially has a relatively small amplitude can be highly informative. To improve its perception against the background of the signal of another channel, balancing is required (usually such a device is present in stereo equipment). To initially set the channel balance, you can equalize the peaks of the quasi-harmonic signals for typical process conditions.

The method of acoustic monitoring of electron-beam technology in vacuum chambers is carried out as follows. In accordance with FIG. 1, a flexible waveguide 2 is removed from the vacuum chamber, which is mechanically connected to the processed sample 1. For the output from the vacuum chamber, the section of the waveguide is compacted. The opposite end of the waveguide 2 is connected to the receiving plate 3, on which the accelerometer 4 is installed, the output of which is connected to the preamplifier 5, connected to the analog amplifier 6, at the output of which the analog-to-digital converter (ADC) 7 is installed, the data of which is stored by computer 8 for further processing and formation of an acoustic display of the vibration signal, which is fed to the headphones 9 used by the operator.

Practice has shown that the duration of the vibration signal that occurs after the irradiation of the part is about 50 ms. The main energy of the signal is concentrated in an even shorter section, sometimes reaching up to 15 ms. If such a signal is fed into the operator's headphones, he will hardly be able to assess only the amplitude of the pulse. In fact, the human ear can distinguish many shades of the signal, including changes in amplitude and frequency composition, but only with a sufficient duration of the analyzed pulse (this is 5-10 seconds). With experience, the operator can evaluate the progress of the process by ear and respond in time to unwanted deviations. When the composition of the processed materials changes, the operator may not wait for the researchers to test various processing modes, but independently determine by ear the appropriate combination of variable modes, comparing them with the subsequent results of the analysis of the quality of the surfaces obtained (after extraction from the vacuum chamber).

However, simply stretching the signal of the initial pulse in time is not the best option, since in this case all frequencies included in the spectrum of the vibration signal (mainly the natural frequencies of the channel connecting the workpiece to the accelerometer) will be reduced by the same number of times as the time is increased impulse. It turns out that many frequencies will be concentrated in a small low-frequency gap, which were previously distributed in a frequency range 100-200 times larger (with a long waveguide, the main vibration energy is concentrated at frequencies up to 20-30 kHz). It turns out such a noise signal, in which it is difficult to disassemble the individual components. It should also be taken into account that miniature acoustic equipment transmits the lowest frequencies worse. There is a lower threshold of about 30-40 Hz, the components that got there will be difficult to make out against the background of components in a higher frequency range. In this regard, in the proposed method, it was decided to single out two frequency ranges from the composition of the vibration signal and to influence the different ears of the operator with their sound display. To do this, the original signal is filtered in these 2 frequency ranges, and the initial envelopes are built (graph 11 in Fig. 2) for each range. The initial envelopes are stretched to a time sufficient for auditory perception (this is 4-10 seconds). It just changes the time scale, for example, 100-200 times. For each selected range, its own carrier frequency of the quasi-harmonic signal is selected, which must be modulated by a new (stretched) envelope. Thus, two quasi-harmonic signals are obtained (example 13 in Fig. 3), which are then differentially amplified and launched into different operator's headphones. In this case, the operator is affected not by a complex noise signal, but by a simplified one, consisting of two quasi-harmonic components, shades (amplitude, modulation, ratio of amplitudes in different ranges at different points in time) whose changes a person is able to catch. The converted signal is launched into the headphones with a certain delay (less than one second), determined by the conversion time in the computer, which does not affect the time for further decision-making by the operator.

The choice of two frequency ranges in which the original signal is filtered is done in advance. It is determined by the composition of the natural frequencies of the vibration observation channel, the distribution of the pulse power over the frequency range, and the frequencies at which the signal amplitude undergoes the greatest changes from pulse to pulse with variations in the irradiation modes accompanying electron beam processing. The frequency range should not be too narrow due to the appearance in this case of instability of the signal amplitude, the most acceptable width of the frequency range is the range of the order of one octave. The choice of the best ranges is carried out on the basis of experimental data. In the example in FIG. Figure 4 shows two quasi-harmonic signals formed to sound two frequency ranges, in which the largest amplitude changes occurred with variations in the working pulses of the electron gun.

The choice of carrier frequencies of quasi-harmonic signals is also made in advance and is guided by the human perception of these signals and their distinguishability when they sound together. Good audial distinction requires that the carrier frequencies differ by a factor of two or more (for this reason, the standard octave division of the frequency range is used). The impact of each quasi-harmonic signal on different ears of the operator improves the differential perception of their features, determined by the course of the technological process. As a frequency range for the carrier frequencies of quasi-harmonic signals, the auditory range of the best perception is used (Conventionally, the area of auditory perception can be divided into three areas: 20 ... 300 Hz - low; 300 ... 3000 Hz - medium; 3000 ... 20000 Hz - high. https:// nssound.ru/o-zvuke-i-zvukovykh-signalakh/oblast-sluhovogo-vosprijatija-cheloveka/). It is preferable to take the lowest carrier frequency from the lower part of the auditory perception range (in the example, a frequency of 70 Hz was used), but above 50 Hz, which is due to the peculiarities of the reproducing equipment. For another channel, the frequency is taken two or more times higher. This does not exclude the orientation on the wishes of the operator. In this case, the second carrier frequency was 250 Hz.

In FIG. 2 and 3 show step by step the sequence of signal conversion in one of the selected frequency ranges (10-19 kHz). These data were taken from the results of experimental processing of vibration signals during electron-beam irradiation of a steel plate coated with an NbHf film. As a result of irradiation, a chemical reaction was triggered with the formation of the nitride phase (NbHf)N. To sound the process, two frequency bands 10-19 and 19-40 kHz were chosen. The transformations in the 10-19 kHz band are shown in FIG. 2 and 3, the same transformations were made for the second strip. Frequencies of 70 and 250 Hz were chosen as carrier frequencies. To improve the perception of sound at a frequency of 250 Hz, the corresponding quasi-harmonic signal was amplified by a factor of 6 before being fed into the headphones to equalize the maximum amplitudes of both signals. As a result, quasi-harmonic pulses with a duration of 5 seconds were obtained (plots 15 and 16 in Fig. 4), where sounds at a frequency of 250 Hz are distinguished at the very beginning, then sounds at a low frequency predominate, modulated by the wave-like nature of martensitic transformation processes. When choosing frequency ranges, it is desirable to take into account that the envelopes of both signals would not be equidistant.

Thus, the claimed set of essential features, reflected in the independent claim, provides the claimed technical result - reducing the time for mastering the technology of processing new materials and increasing the accuracy of setting the operating modes of technological equipment that determine the parameters of electronic pulses and the effectiveness of their impact on the surface of the part, and improving the quality of products of electron-beam processing due to the timely correction of the technological process.

An analysis of the claimed technical solution for compliance with the conditions of patentability showed that the features indicated in the formula are essential and interconnected with the formation of a stable set of necessary features, unknown at the priority date from the prior art and sufficient to obtain the required synergistic (supertotal) technical result.

Thus, the above information testifies to the fulfillment of the following set of conditions when using the claimed technical solution:

- an object that embodies the claimed technical solution, in its implementation is intended for the implementation of electrophysical processing methods, in particular electron beam processing in vacuum chambers;

- for the declared object in the form as it is characterized in the independent clause of the formula below, the possibility of its implementation using the means and methods described above in the application and / or known from the prior art on the priority date is confirmed;

- an object embodying the claimed technical solution, in its implementation, is capable of achieving the technical result perceived by the applicant.

Therefore, the claimed object meets the criteria of patentability "novelty", "inventive step" and "industrial applicability" under the current legislation.

The RIA was created on the topic 18-25 / rnf (Agreement No. 18-19-00599 between the Russian Science Foundation and FGBOU VO MSTU STANKIN).

Claims (1)

A method for obtaining acoustic information for monitoring the technological process of surface alloying of ceramic and hard-alloy tools, which consists in attaching a waveguide in the form of a flexible wire to the object being processed, which goes through a vacuum input outside the vacuum chamber, fixing an oscillation sensor on the waveguide and processing information from the latter using a computer, using an accelerometer as a vibration sensor with a frequency response covering the audible and ultrasonic frequency ranges, recording in time, starting from the moment of exposure to an electron beam pulse, the current values of the signals coming from the accelerometer in two frequency ranges until the signal amplitude drops to the level of background noise , characterized in that the envelopes of the obtained dependencies are selected, which are stretched in time sufficient for auditory perception, forming new envelopes, for a lower frequency range, a carrier is selected frequency of the quasi-harmonic signal within the lower part of the auditory perception range, and for the other range, the carrier frequency of the quasi-harmonic signal in a higher frequency range, sufficient for a comfortable auditory difference with the selected low-frequency quasi-harmonic signal, is selected as the frequency ranges in which the time dependences of the current values are recorded signals from the accelerometer, those frequency ranges are selected in which, according to experimental data, the signal amplitude undergoes the greatest changes with varying irradiation modes, new envelopes are used as modulating functions for the corresponding selected carrier frequencies, the modulated signals are separately amplified and fed to a two-channel sound reproducing device to affect right and left ears of the operator, respectively.

Images