RU2215615C2 - Method for determining optimal cutting speed for hard-alloy tool - Google Patents

Abstract

FIELD: working metals by cutting, working carbonaceous and alloyed steels and refractory alloys. SUBSTANCE: method comprises steps of determining temperature of maximum workability of hard alloy and dependence of cutting temperature from cutting speed. In order to lower labor consumption, setting temperature of maximum efficiency according to temperature of beginning of fracture zone in dependence "temperature - shock ductility of hard alloy". EFFECT: enhanced accuracy of method. 3 dwg

Description

 The invention relates to the processing of metals by cutting, and in particular to methods for determining the optimal cutting speed, which ensures the minimum wear rate and maximum performance of carbide cutting tools for blade machining of carbon and alloy steels, heat-resistant alloys and other metal materials in various engineering industries.

 Known methods for determining the optimal cutting speed according to the graphs of the dependence of various parameters of the tool on the cutting speed [1, 2]. A disadvantage of the known methods is the stopping of the cutting process for intermediate measurements and the use of additional monitoring devices, devices and techniques.

 The closest in technical essence is the known method for determining the optimal cutting speed for carbide tools [3], which consists in the following. According to the results of standard Vickers hardness tests (HV) of tool material samples at various temperatures (Θ) and the graph logHV = f (Θ), the temperature of its maximum performance is determined. Then, the dependence of the cutting temperature on the cutting speed Θ = f (V) is found, by which the value of the optimal cutting speed is determined using the previously set maximum working temperature.

 However, the complexity of this method is relatively high due to the need for a series of measurements while ensuring the constancy of a given test temperature.

 The present invention solves the problem of reducing the complexity of determining the optimal cutting speed based on standard short-term tests.

The solution is as follows. Based on the results of short-term standard tests of carbide samples for impact strength (KCV) at different temperatures, a graph KCV = f (Θ) is constructed, according to which the temperature of the maximum working capacity of the hard alloy Θ _{mr is established} , taking into account the nature of the destruction of the samples. The dependence of the cutting temperature on the cutting speed is revealed, which is used to determine the optimal cutting speed from Θ _mr .

 In contrast to the prototype, the temperature value of the maximum performance of the hard alloy is determined by the results of shorter toughness tests, which not only saves time, but also simplifies the process of maintaining the stability of the test temperature, and also improves the accuracy of measurements.

 The method is based on the established dependence of the nature of the destruction of samples of hard alloy from the temperature of the test for impact bending (figure 1). Depending on the structural state, the degree of relaxation of internal stresses, and the conditions for the propagation of microcracks on the graph, 4 zones can be distinguished: I — brittle, II — quasibrittle, III — viscous, and IV — catastrophic failure. A carbide tool has maximum performance at a transition temperature from a quasibrittle (II) to a viscous (III) state.

 In FIG. 1 shows the dependence of the toughness of a hard alloy on the fracture temperature; figure 2 - dependence of the cutting temperature on the speed of the blade processing; figure 3 - dependence of the relative surface wear of the cutters on the cutting speed.

 The proposed method illustrates an example.

On the graph of the temperature dependence of the toughness of the VK8 hard alloy (Fig. 1), the beginning of the zone of viscous fracture is observed at a temperature of 750 ^o C, which is taken as the temperature of the maximum working capacity of the cutting carbide tool Θ _mr . Using the value of Θ _Mr , according to the dependence of the cutting temperature on the processing speed (figure 2) determine the optimal cutting speed. In the above case, it is 11 m / min.

 Presented for comparison in figure 3, the dependence of the relative surface wear of the cutters on the cutting speed V is based on the results of persistent tests. The optimal cutting speeds determined by the proposed method and resistance tests are the same.

 The proposed method allows to reduce the complexity of determining the optimal cutting speed, ensuring the minimum wear rate of the carbide tool and its maximum performance.

Sources of information
1. A.S. USSR 841779, MKI ³ V 23 V 1/00, publ. 06/30/81, Bull. 24.

2. A.S. USSR 1155361, MKI ⁴ V 23 V 1/00, publ. 05/15/85, Bull. 18.

3. RF patent 2173611, MKI ⁷ V 23 V 1/00 dated 08/20/2001.

Claims (1)

 A method for determining the optimum cutting speed with carbide tools, including determining the temperature of the maximum working capacity of the hard alloy and the dependence of the cutting temperature on the cutting speed, characterized in that the temperature of maximum working capacity is set by the temperature of the beginning of the ductile fracture zone on the temperature dependence of the toughness of the hard alloy.

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