OBRABOTKAMETALLOV MATERIAL SCIENCE Том 23 № 3 2021 EQUIPMEN . INSTRUM TS Vol. 4 No. 4 2022 The experimental setup (Fig. 4) was mounted on a universal high-precision 3G71M flat surface grinding machine with a horizontal spindle and a rectangular table. 140×25×30 mm samples of carbon structural Steel 30 (30 % C) with a hardness of 37–41 HRC in the form of rectangular parallelepipeds were subjected to grinding. A 140×25 mm plane was processed with GW 1. A triangular groove with an angle of 90º and a length of 140 mm was processed with GW 2. The grinding modes are presented in Table 2. Before processing, the grinding wheels are affixed in a statically balanced faceplate, mounted on the machine spindle, and dressed. The aim of each individual experiment is to establish (record) acoustic signals for the established technological conditions. The acoustic signal was recorded using a non-contact sensor. This was a compact directional microphone fixed on a tripod at a distance of 50 – 100 mm from the end surface of the tool. The analog acoustic signal received by the microphone was digitized by a PC sound card. A WDM sound card was used. SOUNDFORGEPro 13.0 was used as the software to work with the acoustic data acquired. The arithmetic mean deviation of the sample profile (Ra, μm) was measured, in order to assess the quality of the ground surface using a contact profilometer with accuracy degree 1, pursuant to GOST 19300–86 (model 130). The processed surfaces were conditionally divided into five equal sections followed by five measurements of roughness inside each section in the direction of the longitudinal feed of the table VS and perpendicular to VS. The length of the baseline that was used to determine the microprofile of the sample surface was 4 mm. The described methodology is a set of elements of the methodologies used in previous studies with a similar focus [23, 24]. The methodology was finalized and adapted taking into account the purpose of the study. The applied equipment, hardware, and software correspond to the purpose and objectives of this work and allow the required parameters to be established with sufficient accuracy. Study of the acoustic signal of idle operation of the experimental setup In the framework of this work, it is necessary to reflect separately the influence degree of “noise” that accompanies the operation of machine units and “noise” that does not carry information useful for research. Even in laboratory conditions, it is impossible to separate the acoustic signal of one particular source. Many elements of the machine system make its own contribution to the overall acoustic picture during processing. A preliminary study of the acoustic signals accompanying the idle operation of the machine is required, in order to achieve an insight into this contribution. When implementing this method in real production, the contribution of other sources of noise signals should be studies. In this study, the various acoustic signals which do not carry information on the properties and condition of the tool will be called noise interference or noise. The signal, generated by the elastic vibrations of the GW during processing and changes depending on the degree of its wear, will be called an informative (useful) acoustic signal [23]. We analyzed the spectrum of acoustic vibrations of the basic elements in the process system, the operation of which is accompanied by noise background. We also considered the spectral composition during the series connection of the systems of (1) power supply, (2) hydraulic power plant, (3) spindle rotation, and (4) longitudinal feed of the table Vs. Results and discussion The section describes the results obtained during the experiment and its interpretation. Natural vibration frequencies and the sound index of the grinding wheels of various profiles Natural vibration frequencies. Figures 5 and 6 show the spectrograms of natural vibration frequencies for GW 1 and GW 2, respectively. Although the material of the grinding wheels and its physical and mechanical properties are identical, the NVF distribution spectra are different. This allows us to assert that the shape of the wheel strongly influences the nature of elastic vibrations.
RkJQdWJsaXNoZXIy MTk0ODM1