RU2520291C2 - Natural thermocouple calibration device - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: device includes a part specimen installed on a mandrel and a cutter, which are insulated from clamping members of the lathe and a cutter holder. With that, the part specimen and the cutting part of the cutter are electrically connected through a current collector and a measuring instrument for recording of thermo-emf. In order to improve measurement accuracy of temperature of the cutting part of the cutter, the device is equipped with an interferometer consisting of a semi-transparent mirror and an optic wedge rigidly attached to the cutter by means of the holder, a recording device of values of thermo-emf and interference images recorded by a video camera, a laser and a collimator to enlarge a beam of coherent monochromic emission. With that, side surface of the cutting part of the cutter is mirror-finished. Transverse slots can be made on periphery of the part specimen.

EFFECT: improving measurement accuracy of temperature of the cutter cutting part.

2 cl, 2 dwg

Description

The invention relates to auxiliary measuring equipment, which is used to monitor cutting tools, namely, the temperature state of the cutting part of the tool during cutting.

A device for calibrating a natural thermocouple part-cutter, selected as a prototype (AS USSR No. 350590, B23B 25/06, publ. 1972, bull. No. 27), which contains two identical samples of the parts mounted on a single mandrel, and two cutters with the same geometric parameters, respectively, processing these samples. Part samples and cutters are carefully isolated from the clamping and mounting elements of the machine. One cutter is a natural thermocouple part-cutter with a processed sample. The second cutter is made detachable in a plane perpendicular to the axis of rotation of the part, and a film of fusible metal is applied to the plane of the connector, according to which the cutting temperature is judged by the fusion zones during cutting. The value of the thermo-EMF of a natural thermocouple is recorded by a measuring device connected to the processed sample through a current collector and to the processing cutter by connecting wires. The device allows you to obtain a calibration graph, correlating the values of the thermo-EMF of the natural thermocouple and the fields of isotherms obtained on a detachable cutter.

The disadvantages of the known device are the low accuracy and the great complexity of calibration, since in order to establish the temperature distribution function in the cutting part of the tool, it is necessary to repeat the experiment repeatedly to obtain each point of the calibration graph, namely, periodically remove the tool from the machine, disassemble it and fix the reflow zone under the microscope.

The objective of the present invention is to improve the accuracy and reduce the complexity of calibration of a natural thermocouple.

The technical result in solving this problem is to use a high-precision non-contact interferometer to measure the temperature field in the cutting part of the cutter.

This technical result is achieved due to the fact that in the known device for taring a natural thermocouple, which contains a sample of the part mounted on the mandrel, and a cutter isolated from the clamping elements of the machine and the tool holder, while the sample part and the cutting part of the cutter are electrically connected through a current collector and measuring device for recording thermo-EMF, a feature is that it is equipped with an interferometer consisting of a translucent mirror and an optical wedge rigidly connected to the cutter by means of the holder, means of recording the values of thermo-EMF and interference patterns recorded by a video camera, a laser, and a collimator to expand the beam of coherent monochromatic radiation, while the side surface of the cutting part of the tool is made of mirror-polished. In addition, transverse grooves can be made at the periphery of the sample of the part.

Figure 1 shows a diagram of a device for taring a natural thermocouple part-cutter; figure 2 - diagram of a device with a sample of a part made with transverse grooves.

The tare device comprises a natural thermocouple consisting of a sample of part 1 mounted on a mandrel and a cutter 2 isolated from the clamping elements of the machine 3 and tool holder 4. The sample of part 1 and cutter 2 are electrically connected to each other through a measuring device 5 and a current collector 6 using connecting wires. The device also includes a recording means 7, a laser 8, a collimator 9 for expanding a beam of coherent monochromatic radiation, a video camera 10 and an interferometer consisting of a translucent mirror 11, an optical wedge 12 and a mirror-polished side surface 13 of the cutting part of the cutter 2, the optical wedge 12 is rigidly connected to the cutter 2 by means of a special holder 14. A sample of part 1 can be made with transverse grooves 15 located at its periphery with a certain step.

The device operates as follows. A sample of part 1 is sharpened at a radial feed, as a result of which in the circuit a sample of part 1 - current collector 6 - measuring device 5 - cutter 2 produces a thermo-emf. Simultaneously, using an interferometer consisting of a translucent mirror 11, an optical wedge 12 and a mirror-polished side surface 13 of the cutter 2, interference patterns are formed that carry information on the temperature fields arising in the cutting part of the cutter 2, which can be determined by the formula

,

,

where T ₀ is the initial temperature of the cutting wedge before cutting (T ₀ = 20 ° C);

T _t - temperature at the considered point of the cutting wedge;

m _t is the difference of the orders of interference fringes at the considered contour point of the cutting wedge before cutting and after removing the cutting part of the tool from the cutting zone at an interesting point in time;

λ is the wavelength of monochromatic coherent radiation;

t is the thickness of the cutting wedge before it deforms at a temperature T ₀ ;

α is the coefficient of thermal expansion of the tool material.

The value of the thermo-EMF recorded by the measuring device 5, and the image of the interference patterns recorded by the video camera 10, are continuously transmitted to the recording means 7, where they are correlated and the calibration dependence is determined. Since the information on temperature fields is provided by interference patterns obtained at the moment of removing the cutting part of cutter 2 from the cutting zone, a sample of part 1 with transverse grooves 15 located at its periphery with a certain step is used to reduce the number of experiments.

Thus, the described device for taring a natural thermocouple through the use of high-precision non-contact interferometric measurement of temperature fields in the cutting part of the tool can reduce the complexity and increase the accuracy of taring.

Claims (2)

1. A device for calibrating a natural thermocouple containing a sample of the part mounted on the mandrel and a cutter isolated from the clamping elements of the machine and the tool holder, while the sample of the part and the cutting part of the cutter are electrically connected through a current collector and a measuring device for recording thermo-EMF, characterized in that it is equipped with an interferometer consisting of a translucent mirror and an optical wedge rigidly connected to the cutter by means of a holder, means for recording the values of thermo-EMF and interference patterns, recorded by a video camera, a laser and a collimator to expand the beam of coherent monochromatic radiation, while the side surface of the cutting part of the cutter is mirror-polished. 2. The device according to claim 1, characterized in that transverse grooves are made on the periphery of the sample.

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