SU1227339A1 - Method of determining the optimum cutting speed - Google Patents

Description

The invention relates to metal cutting and can be used to determine the optimal cutting speed, which provides the minimum wear rate of a carbide cutting tool and its maximum durability at the optimum cutting temperature (9 ° C).

The purpose of the invention is to increase accuracy and reduce labor intensity in determining the optimal cutting speed.

FIG. 1 shows the dependence (ADAP) on the carbide material at different temperatures; in Fig.2, the dependence of the shape parameter of the curve (F) on the heating temperature of the solid alloy; in fig. 3 - nomogram for determining the optimal cutting speed when machining various steels; in fig. 4 is a setup diagram for measuring the ADAP curves for the hard alloys under study; in fig. 5 - determination of the optimal cutting speed when machining steel 2 18H10 with a VK 8 carbide chisel.

The method is carried out as follows.

Determine the temperature in cus-a-vis from the cutting speed on a turning-cutting machine by the method of a natural thermocouple. Thermocouple calibration is performed using standard methods. Build a graph of 0 f (V) according to the temperature of cutting - speed. Next, the dependence of the ADAP parameter (angular distribution) of the annihilation photons on temperature is determined by measuring on a long-slit installation equipped with a heating device that allows the sample temperature to be varied from 200 to (D), and in the process of recording the intensity of annihilation photons at consecutive relative displacement of the positron source with the sample — a carbide plate and the receiver of the specified radiation — at a certain angle builds an ADAP curve. In this case, the carbide plate (sample) is exposed to 10 mCuri of the 22 Na source positrons at a predetermined temperature, as a result of which the positrons injected into the surface of the hard alloy thermolize for 10–10 s and annihilate on the valence electrons belonging to the defective regions , or on the electrons of the defect-free region of the crystal lattices. An nigil-quanta, formed as a result of the reaction J t e 2 y, carry information about the momentum distribution of electrons in atoms. Annigil qi positron with an electron

belonging to the defect contributes to the pulse counting intensity in the so-called small-angle region of the ADAPT curve at a relative angle of displacement close to 0 o mrad. Positron annihilation in the defect-free region of the structure contributes to the counting intensity of photon pulses in a wide range of angles of the ADAP curve region close to 9 10 mrad.

Passage through collimators, annihilation quanta are recorded by receivers (scintillation sensors) and, through special equipment, their intensity (the number of pulses - annihilation acts per unit time) is digitally transmitted to a reader. According to the measurement results, for each given temperature, the ADAP curves plotted the dependence of the positron annihilation intensity on the magnitude of the angular parameter expressing the relative displacement of the annihilation source and the Jf-quantum receiver (Fig. 1).

After constructing an ADAP for each given temperature, depending on the displacement angles, calculate the so-called parameter (0) / N (10), which characterizes the shape of the ADAP curve

and expressing the degree of imperfection of the structure of the solid alloy. Here, N (0) is the counting rate at the ADAP peak at an angle of relative displacement of 9 O mrad and N (10) is the counting rate

annihilation properties in the ADAP region approximated by the Gauss curve at an angle of relative displacement of 8 10 mrad.

By calculating the value of F for each temperature at the ADAP study, a graph of the curve shape parameter (characteristics of the degree of defectiveness of the structure of a hard alloy) is plotted versus temperature (Fig. 2).

To determine the optimal cutting speed, it suffices to build the capacity (6) of the degree of defect in the structure of a solid alloy (the shape parameter of the ADAP curve) from temperature, to set the temperature at which the extremum is observed - to substitute its minimum value found (based on experimentally confirmed correspondence S (F) 0 ( 0)) the value of temperature 6 (F) in the found dependence 9 f (V) of the cutting temperature on speed and determine from this dependence the optimal cutting speed. Due to the different ascending nature of the bf (V) curve for each material, the optimum temperature will be different in each case (Fig. 3).

The installation based on the measurement of the ADAP curves as a function of the temperature state of the sample under study makes it possible to measure with high productivity. The installation for measuring the ADAP curves for the hard alloys under study contains a source of 1 positron 22 Na with an activity of 10 mCi; test sample 2 made of hard alloy, located on a special table equipped with a heating device, collimators 3, detectors (receiving device for recording annihilation photons) 4, special equipment 5, determining the ratio of counting rates and transferring information to the reader.

Example. On the proposed device, by determining the angular distribution of annihilation photons) equipped with a heating device, the annihilation characteristics are determined depending on the temperature of the carbide VK 8 plate.

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The tatam of measurement and processing of experimental data is used to plot graphs (9) according to the curve shape parameter (defectiveness parameter) —J heating temperature. It is found that the minimum value of the imperfection of the structure of a solid alloy of VK 8 corresponds to a temperature equal to 8 (F) 640 C.

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In the process of cutting on a lathe of the model of the 163 chromium-nickel steel 12X18H10T of austenitic class using a natural thermocouple method, the average temperature in the contact Cutter - the material being processed on the cutting speed is determined. For studies, tetrahedral carbide plates of VK 8 with a front angle, a rear angle oi 5, angle in the plan (., Auxiliary angle in the plan tf, 45 are used. The feed in all experiments is constant and equal to 3 mm / rev, and

25 depth of cut - mm. Tests performed without cooling. Cutting speed varies from 20 to 10 ohm / min. Thermocouple BK8 - 12X18HIOT pre-calibrated. Based on the measurement of the thermo-emf and the tariro data. In this case, the temperature dependence of the cutting velocity f (V) is plotted (Fig. 5).

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Substituting in the obtained dependence (V) value in (F) 640 G, at which the minimum defectiveness of the structure of the hard alloy is observed, the cutting speed corresponding to the optimal cutting speed and equal to m / min is graphically determined, which is in good agreement with the classical resistance. tests.

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Claims (1)

METHOD FOR DETERMINING THE OPTIMAL CUTTING SPEED for carbide tools, including determining the dependence of temperature on cutting speed with plotting this dependence Θ = f (V) and assigning as the optimum speed the speed corresponding to the dip temperature of the material being processed, characterized in that, in order to to increase accuracy and reduce the complexity, as the optimal speed assigns the cutting speed corresponding to the heating temperature of the carbide plate, at which the minimum value of the shape parameter of the curve of the angular distribution of annihilation photons is observed. (Riga. 1 eleven