RU2287787C1 - Method of measuring value of temperature field, of temperature in area of cutting and character of its distribution in processed material - Google Patents

Abstract

FIELD: measuring technique.

SUBSTANCE: device allows measuring temperature at area of cutting at application of blade and diamond-abrasive tools as well as by tools made of super-hard materials. Artificial thermocouple is mounted in processed material and output voltage of the thermocouple is subject to oscillography. During process of treatment of material, toll is continuously advanced till touching thermocouple. When processing received oscillogram, preliminary value of temperature field is determined, which value later is subject to increase by size of thermocouple's junction, and function approximating character of temperature distribution in treated material is built. The function is extrapolated from point of touch of instrument with thermocouple to point of transition of thermal electrodes into junction; approximation allows determining temperature in area of cutting.

EFFECT: improved precision of measurement; improved reliability.

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Description

The invention relates to the field of temperature measurement, in particular to methods for determining the temperature in the cutting zone and the nature of its distribution in the material being processed using blade and abrasive tools, as well as tools made of superhard materials.

A known method for determining the temperature of the grinded surface of the metal in the cutting zone using a cut thermocouple, consisting of a part and a thermoelectrode placed in the grinded part (1). According to this method, a mortgage shear thermoelectrode is pre-coated with an electrically insulating varnish and pinched normal to the grinding surface between the two halves of the test sample. The cut-off semi-artificial thermocouple thus obtained “part-embedded cut-off thermoelectrode” is connected to an electronic oscilloscope, the magnitude of the output voltage of this thermocouple is determined from the oscillograms and the contact temperature is calculated by a certain dependence.

The disadvantage of this method is the inability to determine the temperature in the cutting zone and the nature of its distribution in the processed material, when the processed and cutting materials are dielectrics, since the known method is applicable only when processing parts from electrically conductive materials that form a semi-artificial thermocouple with embedded thermoelectrode.

There is also a method of determining contact temperature and the nature of its distribution in cutting tools using an artificial thermocouple (2). According to the known method, during the tool wear periodically, simultaneous measurements are taken of the distances from the junction of the thermoelectrodes to the junction to the working surface of the crystal and the temperature values corresponding to these distances, followed by approximation of the experimental results by a function subsequently extrapolated to the cutting zone (to the junction of the thermoelectrodes).

The disadvantage of this method is the inability to use it to determine the magnitude of the temperature field, the temperature in the cutting zone and the nature of its distribution in the processed material when sawing, for example, natural stones (granite, marble). The implementation of the known method involves the preliminary installation of a thermocouple in natural stone, the sequential execution of a series of passages (cuts) with a diamond wheel at various distances from the thermocouple while measuring the temperature corresponding to a certain distance from the thermocouple to the cutting zone.

However, the small temperature field that is formed around the cutting zone during sawing (processing) of natural stone with a diamond disc wheel working with abundant cooling limits the number of passes (cuts) performed as we approach the thermocouple and are required to approximate the experimental results by the desired function (segment width circular saws is 3.0 ... 10.0 mm; a strip must also have a large width, which should be cut from the stone at the next pass (cut)).

The aim of the invention is the simultaneous determination of the magnitude of the temperature field, the temperature in the cutting zone and the nature of its distribution in the processed material during the machining of workpieces with blade and abrasive tools, as well as tools made of superhard materials.

The technical result is achieved due to the fact that during the cutting process the tool is continuously fed towards the thermocouple until it comes in contact with it. At the same time, the temperature value is fixed, which increases as the cutting zone approaches the thermocouple installed in the processed material. At the moment the tool contacts the hot junction of the thermocouple, the nature of the increase in the cutting temperature changes sharply. The change in cutting temperature corresponding to the time of continuous approach of the tool and the thermocouple is approximated by a function that characterizes the temperature distribution in the material being processed. The portion of the waveform corresponding to an increase in the cutting temperature (to the point of contact of the tool with the thermocouple) and increased by the size of the junction of the thermocouple characterizes the magnitude of the temperature field. Extrapolating the approximating function from the point of contact of the instrument with the thermocouple to the point of transition of the thermoelectrodes to the junction allows one to determine the temperature in the cutting zone.

The drawing shows a characteristic waveform of temperature changes during sawing of natural stone with a diamond cutting wheel, explaining the proposed method. Point 1 corresponds to the beginning of an increase in the cutting temperature, and point 2 corresponds to the moment of contact of the tool with a thermocouple, which is accompanied by a sharp increase in temperature (section 2-3). To point 1, the temperature field has not yet reached the point where the thermoelectrodes transition into thermocouple junctions (therefore, there are no changes in the oscillogram). On the site "a" (the plot of the further approach of the tool and the thermocouple), the temperature rises from point 1 to point 2, which corresponds to the nature of the distribution of the cutting temperature in the processed material. Knowing during the experiment the speed of drawing of the photosensitive paper on the oscilloscope, as well as the time of the temperature rise (in the area between points 1 and 2), you can determine the length of the section "a", which corresponds to part of the temperature field in the direction of supply of the instrument (the entire temperature field in the indicated direction consists of sections “a” and “b”, and section “b” is equal to the size of the thermocouple junction). To determine the temperature value in the cutting zone, the oscillogram in section “a” is approximated by a function, which is then extrapolated from the point 2 of the contact of the instrument with the thermocouple to the point of transition of the thermoelectrodes to the junction (to point 4).

Thus, the proposed method allows to determine the magnitude of the temperature field, the temperature in the cutting zone and the nature of its distribution in the processed material. The developed method allows to evaluate the indicated temperature characteristics of the cutting process, taking into account changes in the thermophysical properties of the processed materials, depending on temperature. The method can be used not only in the processing of natural stones, but also in other types of machining, involving the possibility of continuous approximation of the tool and the thermocouple installed in the processed material (for example, during drilling, milling, etc.).

Determination of the temperature field and the temperature in the cutting zone, as well as the nature of its distribution in the processed material, will further optimize the technological processes of mechanical processing of materials. The implementation of the proposed method will contribute to the development of methods to increase the durability of blade tools and grinding wheels, as well as the resource of tools made of superhard materials.

Information sources

1. Zhabokritsky R.A. A method for determining the temperature of a metal surface being polished in a cutting zone with a cut-off thermocouple consisting of a part and a thermoelectrode placed in a grinded part. - A.S. USSR, No. 468108, G 01 K 7/08.

2. Hapachev B.S. A method for determining contact temperature and the nature of its distribution in cutting tools. - Decision on the grant of a patent for an application for invention No. 2003116115/28, G 01 K 7/04, G 01 N 3/58.

3. Sukhobrus A.A. and others. A method for determining the temperature in the cutting zone. - A.S. USSR, No. 522049, B 24 V 49/14, B 23 Q 15/00.

4. Reznikov A.N., Reznikov L.A. Thermal processes in technological systems. - M.: Mechanical Engineering, 1990. - 288 p.

Claims (1)

The method of determining the magnitude of the temperature field, the temperature in the cutting zone and the nature of its distribution in the processed material using an artificial thermocouple, which consists in oscillographing its output voltage, characterized in that during the cutting process the tool is continuously fed to contact with a thermocouple installed in the processed material, the oscillogram determines the preliminary value of the temperature field, which is then increased by the size of the thermocouple junction, and the approximating distribution The temperature setting in the material being processed is a function, and to determine the temperature in the cutting zone, the function is extrapolated from the point of contact of the instrument with the thermocouple to the point of transition of the thermoelectrodes to the junction.