RU2422800C1 - Procedure for prognosis of wear resistance of hard alloy cutting tools - Google Patents

Abstract

FIELD: machine building. ^ SUBSTANCE: resource of trouble-free operation of given cutting tools depends on intensity of diffusion processes in zone of contact with machined material. Surface structure of hard alloys greatly influences a value and direction of the said destructive phenomenon. Prognosis and control of wear resistance of cutting tools are carried out with consideration of value of complex force coefficient and concentration of base active centres - pH obtained at crumbled hard alloy mass. The procedure is based on close correlation between surface properties of crumbled hard alloy mass: value of force coefficient and concentration of acid-base active centres -pH and wear resistance of hard alloy cutting tools. Wear resistance of hard alloy cutting tools of the said group increases, when pH of crumbled hard alloy mass decreases. ^ EFFECT: upgraded accuracy and reduction of labour input at prognosis of wear resistance of tungsten-titan-cobalt, of group of applicability P, of cutting tools. ^ 1 dwg

Description

The invention relates to the field of metal cutting and can be used to predict - control the wear resistance of carbide cutting tools in their manufacture, use or certification.

A known method for determining the wear resistance of hard alloys is that the test material is placed in an alternating magnetic field with an intensity of the order of 5 Oe, the magnetic permeability of the material is measured, and the magnitude of the material’s wear resistance is determined from the magnetic permeability – resistance calibration chart constructed for the reference sample [ SU A.S. 268720, IPC G01N 3/58, BI 1970, No. 14].

One of the disadvantages of this method is that the measurement does not take into account the influence of the mass and demagnetizing factor of products, which often have different shapes and dimensions, on the magnetic permeability, which leads to a decrease in the accuracy of measurements. In addition, the operational characteristic - wear resistance - is controlled by this method by assessing the physical condition using relative magnetic permeability in only one of the components of the hard alloy - cobalt bond. This is because tungsten carbide is a paramagnet, and its contribution from magnetization to the total relative magnetic permeability is small. Therefore, using this method, essentially, the relative magnetic permeability of cobalt, its quantity and deformation state are evaluated. Moreover, other properties of the surface and volume of the hard alloy are not taken into account at all, including the cohesive and adhesive state at the phase boundaries and in the volume of the components of the hard alloy, etc. Due to the reasons considered, this method is characterized by low accuracy in assessing the wear resistance of hard alloys.

A known method of controlling the cutting properties of a batch of carbide tools, according to which first they act on each tool (carbide plate) from the batch, a control parameter is recorded, then several tools from the batch are selectively subjected to mechanical wear and the cutting properties of the tools of the entire batch are determined. The impact on each tool is carried out by uniformly distributed pulsed heating, a chronological thermogram is recorded, the thermal diffusivity of each instrument is determined as a control parameter by the results of a selective wear mechanism depending on the thermal diffusivity, and the cutting properties of the tools of the entire batch are determined using the obtained dependence [SU A. FROM. 1651155, IPC G01N 3/58, BI 1991 No. 19]. The selected initial parameter in this method is the thermal diffusivity. The main disadvantage of this method is that it is very difficult to more or less accurately determine the rate of heat propagation in materials in which free electrons are the heat carriers. Hard alloys are such materials, and their heat transfer is ensured by the movement of electrons. The thermal diffusivity of all hard alloys differs by an insignificant amount. Therefore, it is very difficult to determine the fluctuations (changing the wear resistance) of the thermal diffusivity for one particular grade of hard alloy (they are almost invisible). The latter is fraught with great technical difficulties. The proper provision in this situation of control operations with precise - acting, recording and auxiliary instruments and devices guaranteeing the necessary accuracy will entail a significant increase in the cost of control operations. As a result of this, this control method is not very promising for use in both laboratory and production conditions.

A known method for predicting the wear resistance of a cutting tool, selected as a prototype and consisting in the following. Carry out benchmark tests of cutting tools at an optimal or close cutting speed, conduct tests to change the value of the initial parameter on the properties of the surface polyoxide structure of the hard alloy formed during its heating, build the reference correlation "initial parameter - wear resistance", perform statistical monitoring only initial parameter values for the current batch of carbide cutting tools. After that, wear resistance is predicted for the current batch of tools based on the relationship:

where T (current), min - wear resistance in minutes - the average predicted time of trouble-free operation of carbide cutting tools undergoing tests from the current batch of samples;

T (reference), min - average wear resistance in minutes for carbide cutting tools from a reference batch of carbide products;

τ (reference), ps - the average value of the selected initial parameter obtained by measuring the characteristics of the surface polyoxide structure of carbide cutting tools from a reference batch of carbide products;

τ (current), ps - the average value of the selected initial parameter obtained by measuring the characteristics of the surface polyoxide structure of carbide cutting tools from the current - controlled batch. In this case, the value of the positron lifetime embedded in the surface and near-surface layers of hard alloys and estimating the electron density of their structure is used as the initial parameter. The magnitude of the electron density predict the wear resistance of manufactured cutting tools. [SU A.S. 2251095, IPC G01N 3/58, BI 2005 No. 12]. The main disadvantage of this method is the high organizational complexity in its implementation. To implement this method, a radioactive source is required. In accordance with the standards for its maintenance, there are high requirements. It is necessary to have a special room for its storage. Measurement of the relevant parameters and processing of the results obtained can only be done by specially trained and trained personnel. Using this method, the structure is evaluated at the atomic level and the results are not always compared with the results obtained by wear resistance, leading to an accurate forecast. This method allows you to sort out - to predict the wear resistance of hard alloys similar in appearance and degree of defective structure. Comparison of structures that differ greatly in appearance and degree of defectiveness gives quite noticeable errors in the forecast of wear resistance of carbide cutting tools. As a result, this method for predicting wear resistance does not quite accurately characterize the operational properties determined by the degree of defective structure, which ultimately reduces the degree of tightness of the correlation between the initial parameter and the wear resistance of cutting tools. Nevertheless, this control method informatively reflects the operational state of the surface structure of the tool material, which is important for establishing a relationship between this characteristic and adhesive wear, which largely depends on the type and degree of imperfection of the surface layer, and we choose it as a prototype.

The objective of the proposed method is predicting the wear resistance of carbide tungsten - titanium - cobalt, applicability group P, cutting tools - is to increase accuracy and reduce the complexity when predicting the wear resistance of carbide cutting tools. Prediction is based on a close correlation between wear resistance and acid-base properties — pH of the surface milled structure of hard alloys of the usability group R. With a decrease in the complex indicator of acid-base properties of the milled surface structure — the pH is the wear resistance of carbide (group P) cutting tools (cutting plates) when they cut steels and alloys increases.

The task in predicting the wear resistance of carbide cutting tools of the applicability group P in the proposed method is solved by using the selected initial parameter and includes: conducting statistical tests of wear resistance in the process of cutting machine-building materials on a metal-cutting machine, measurement - monitoring of the initial parameter, building a correlation - reference dependence " wear resistance - initial parameter ”and subsequent statistical control exclusively o only the value of the initial parameter of the current controlled batch of carbide cutting tools (or individual tools) based on the relationship:

where a _E and in _E are constant coefficients:

,

,

where T _pt (min) is the current youth resistance in minutes for carbide cutting tools (inserts) that have been tested from the forecasted current batch of carbide products;

pH _pt (b / c) - the current value (dimensionless value) of the selected initial parameter obtained when controlling the crushed carbide mass (structure) from carbide cutting tools (plates) from the current controlled batch of carbide products;

(мин) - износостойкость в минутах для двух выборок сменных твердосплавных режущих инструментов (пластин) из эталонной партии твердосплавной продукции;

(min) - wear resistance in minutes for two samples of interchangeable carbide cutting tools (inserts) from the reference batch of carbide products;

pH _e1 and pH _e2 (b / c) are the dimensionless values of the selected initial parameter obtained by monitoring the crushed carbide mass from two samples of carbide cutting tools (plates) from a reference batch of received (sent) products, characterized in that in order to increase the accuracy of predicting wear resistance as an initial parameter, use the value of a complex indicator of the strength and concentration of acid-base active centers in the surface ground carbide mass (structure) tools (plates) - pH, with a decrease in which the wear resistance increases.

The surface and near-surface structure of a carbide cutting tool, which is formed during the manufacture (sintering) of a hard alloy, has a great influence on its wear resistance. One of the most important properties of the surface structure of hard alloys, which determines the most important physicochemical and operational characteristics of carbide cutting tools, is a comprehensive indicator of the concentration and strength of active centers (degree of acidity or basicity). The surface structure of carbide, the group of applicability P, cutting tools has mainly active centers of the acid type, which creates mainly titanium carbide. When involved in chemical reactions with other objects (processed material, gas environment, etc.), acid active sites belonging to the surface are effective electron acceptors and proton donors. The type of active sites and the degree of their acidity or basicity (which depends, among other things, on the saturation of the structure with vacancies or impurity atoms, etc.) significantly affects the chemical activity of surface atoms of the carbide structure with respect to atoms and molecules of the surrounding gas environment. With an increase in the concentration of acid active centers with a low electron density in the carbide structure, the intensity of interaction of the surface with oxygen atoms decreases, and with hydrogen atoms it increases. Adsorption of hard alloys by the working surface during their operation of water molecules leads to its decomposition into protons and hydroxyl groups. Hydrogen ions react with titanium carbide to form titanium hydrides. The hydroxyl groups are previously dissociated into oxygen and hydrogen atoms, are embedded in the crystal lattice of titanium carbide and form solid solutions. Hydrogen gives off an electron at relatively low temperatures and easily ionizes, forming titanium carbohydrides and hydrides. Oxygen only at higher temperatures replaces carbon atoms in the carbide compound and forms a titanium surface oxycarbohydride structure with high heat-insulating properties. The intensity of electron capture by an active center created by titanium and carbon atoms, and the formation of titanium hydride, carbohydride or oxycarbohydride depends on the stoichiometric composition of carbide grains, the type and degree of imperfection of the titanium carbide crystal lattice, the level of chemical interaction between titanium and carbon, and the nature of hybridization of the established bonds. At a high concentration of non-stoichiometric carbide compounds in the hard alloy composition, which have an increased electron density and a low probability of electron capture in order to form an electron pair, the energy required to break existing chemical bonds (metal-carbon) and form new ones (metal-hydrogen), primarily in the field of concentration of active centers, is relatively high. In the resulting titanium carbohydrides, carbon is in a divalent state. At a high concentration of stoichiometric carbide compounds in the hard alloy composition having a low electron density and a high probability of electron capture, the energy required to break down existing chemical bonds and form new active centers in the concentration region is relatively low. In this case, during the reactions of titanium carbide with hydrogen, titanium carbohydride compounds are formed in which carbon is in the tetravalent state. The compounds of titanium carbohydrides with tetravalent carbon have a predominantly hexagonal crystallographic structure. Moreover, the main base plane is parallel to the surface plane, forming a layered structure. The interlayer space is an effective area for the dissipation of thermal energy and reduce its tension as a result of a decrease in concentration gradients. As a result, the surface and near-surface structure of carbide group of applicability P of cutting tools is an effective barrier against diffusion and heat propagation, which helps to reduce high-temperature wear. The surface of the hard alloy will be transformed to a greater extent upon initial saturation with hydrogen and subsequent oxidation due to atmospheric oxygen into a structure favorable for the acquisition of heat-insulating properties, the more it was initially solid acid. The concentration and strength of acidic and basic centers on the surface and in the surface layers of hard alloys depends on the composition of the charge from which hard alloys are made, on the degree of mechanical action on titanium carbide powder during grinding, on the level of saturation of titanium carbide with carbon, on the temperature conditions of sintering, on the medium sintering (vacuum, reducing gas), etc. The concentration of states with increased or decreased acidity or basicity (with increased or decreased electron density in the region where active centers are located both on the surface and in the surface layers of hard alloys) is influenced by the nature of the distribution of carbide grains over fractions, the type and level of stoichiometry of carbide compounds ( compounds with excess or deficiency of carbon or titanium), the degree of interaction between titanium and carbon, the nature and type of formation of electronic bonds, including gy bridged, depending on the presence of various impurities, stabilizing, in turn, the acidic or basic nature of the structure of the hard alloy.

The effective degree of acidity or basicity of active centers is affected by the nature of their distribution on the surface and in the volume of the hard alloy. At the same concentration of different active centers on the surface and in volume, but at different locations, the resulting acidity or basicity will vary greatly. This, in turn, leads to an uneven distribution of hydrogen atoms in carbide grains and, accordingly, in interplanar space. The latter is the reason for the decrease in the strength of the chemical bond between titanium, carbon, and hydrogen both in the basal planes and between the individual layers. The non-optimal nature of the arrangement of active centers also leads to a decrease in the efficiency of the formation of the oxycarbohydride heat-protective layer during operation of carbide cutting tools. It is possible to control the level of concentration of active centers and their distribution in strength in the surface structure of a hard alloy, including by introducing alloying elements into the charge that enhance or weaken the degree of acidity or basicity of active centers that are less or more active with respect to oxygen, so to hydrogen. As a result of targeted doping, the acidity level of the surface structure may increase. The latter will lead to an increase in its activity with respect to elements - electron acceptors, to an increase in the adsorption of negatively charged anions - hydroxyl groups, to their dissociation into atoms and to saturation of the surface region with hydrogen, which forms solid solutions with titanium and carbon. Due to the cooling of hard alloys after sintering in a hydrogen medium, partial decomposition of solid solutions occurs, and a layered structure is formed in the surface region with alternating individual layers with a high and low hydrogen content. As a result of the formation of a surface and near-surface structure of a hard alloy with a high concentration of acceptor centers, the degree of oxidation of the surface decreases. The interaction with oxygen at high temperatures is accompanied only by partial oxidation of the surface layers and the formation of a stable structure. On the surface and in the near-surface region, a complex of ordered oxycarbide layered formations is formed, which have a high density and high ability to resist high-temperature - diffusion wear. An increase in the concentration and strength of acid centers (with an increase in the composition of titanium carbide) is associated with the formation of stoichiometric carbides on the surface and in the surface region. The latter interact more effectively with hydrogen, which is accompanied by the formation of heat-insulating and anti-diffusion layered structures. The concentration and strength of acidic active sites in the surface structure depends on the initial composition of the hard alloys and the conditions for their preparation. A state with an increased or decreased concentration of acid active centers in the structure of hard alloys arises due to the different composition and properties of the initial samples from hard alloys, the presence of titanium carbide in the composition, carbon deficiency or excess in carbide compounds, and the degree of defect of the cobalt component due to the characteristics of solid-state reactions between tungsten, titanium and cobalt carbides at the stages of preparation of components and final sintering of composites. With an increase in the concentration of acidic active centers, the intensity of the chemical interaction of the contact surface of the carbide cutting tool with atmospheric gas elements and the material being processed decreases and, accordingly, its wear resistance increases.

The process of controlling the concentration of active centers in the surface structure can be carried out, first of all, by doping the composition of hard alloys with donor or acceptor impurities or other elements that affect the formation of a structure with increased or decreased acidity (with reduced or increased electron density at local points). As a result of increasing the surface acidity level and decreasing its activity with respect to oxygen, the level of diffusion interaction of rubbing surfaces in the contact zone will decrease due to the formation of a dense and heat-resistant surface structure (based on titanium oxycarbohydrides) with sufficiently high mechanical properties. An increase in the strength of acid centers belonging to the surface of a hard alloy occurs as a result of a redistribution of electron density in a carbide compound and a change in the ratio in the interaction between metal and carbon atoms. Due to these reasons, the saturation of the surface of the hard alloy with atoms and molecules of the surrounding gas environment (including oxygen), as well as with the elements of the material being processed, decreases and, accordingly, the activity of solid-phase reactions that break up the surface of the cutting tool, initiated by high-temperature diffusion wear, decreases. The destruction of the surface is also prevented by a significant decrease in the chemical potential of the layered structure. It follows from this circumstance that it is the acidic nature of the surface and, accordingly, the sufficient concentration of acidic active centers on the surface and their strength that determine the formation of an ordered layered hydroxyhydrohydride surface structure with sufficiently high heat-insulating and heat-resistant properties. Such a structure of the surface structure leads to a decrease in the coefficient of friction, cutting forces and, as a consequence, to a decrease in the intensity of diffusion wear. The degree of acidity of the surface structure is closely related to the electron density of the substance and, accordingly, to its defectiveness. With the transition from defectiveness, which causes an increase in electron density, to defectiveness, which leads to a decrease in electron density at local points, the acidity of local active centers increases. The acidity of the surface is not continuous. Acid active regions are centers with reduced electron density, located at local points - centers. Moreover, the strength of acid centers and the place of their dislocation (location) take a certain probabilistic law of their distribution on the surface, characteristic of each specific structure formed on the surface of a particular hard alloy. Small and large pores also form a certain degree of acidity in the structure of the hard alloy. With an increase in their concentration, the concentration of acidic active sites and their strength increase. This leads to an increase in total surface acidity. The surface acquires a tendency to less active and more ordered formation of compounds with atoms and molecules of the surrounding gas medium. The surface and surface structures formed and regenerated due to the presence of active acid sites on the surface are an effective heat-insulating and anti-diffusion screen, which ultimately reduces wear and increases the wear resistance of carbide cutting tools and their operational efficiency. Thus, the lower the pH of the surface structure of the carbide cutting tool (the greater the acidity of the surface), the lower the intensity of the interaction of the surface with atoms and molecules of the surrounding gas medium and the material being processed, and therefore the manifestation of diffusion wear. The integral wear of the carbide cutting tool is reduced, while operational performance is increased. The acidity of the surface increases with increasing degree of stoichiometry of the forming carbides, which, in turn, is determined by the composition, structure and properties of the starting components. It is also possible to change the acid-base properties of surface solid acids or bases (as applied to instrumental materials) by heat treatment, irradiation, or by doping with various elements, causing active centers to be effective electron acceptors or donors. The nature of the pH is affected by the chemical composition of carbide grains, the type of chemical bond between metal and carbon, the dispersion of carbide particles, the type and degree of imperfection of carbide compounds, the temperature and duration of sintering, sintering conditions (vacuum, protective atmosphere, duration of sintering, etc.).

An essential feature of the proposed method is that, in accordance with its methods without additional costs and technical difficulties, it seems possible to conduct a more objective and accurate assessment of wear resistance due to operational analysis and comparison of current controlled and reference parameters obtained in a wide range of cutting conditions. The properties of carbide structures formed during sintering of hard alloys and transformed in the contact zone are significantly affected by protective coatings and various surface hardenings, however, in this case, between wear resistance and a complex indicator of acid-base surface properties of hard alloys, as tests have shown , there is also a stable correlation.

The implementation of the method is carried out sequentially, passing through several stages. First carry out benchmark tests. For this, a fairly representative sample of carbide (group P) cutting tools (cutting inserts) is made from an existing batch of carbide products and they are tested for their wear resistance during cutting on a metal cutting machine, usually steel, causing intense diffusion wear. The cutting is carried out at an optimum or close to the cutting speed [See, for example, RU 2168394 C2 7B23B 1/00 from 10.06.01. Bull. No. 16]. The amount of wear resistance is determined as the uptime for a specified blunting criterion - the wear facet on the back surface (usually 0.2-0.8 mm). Then, carbide cutting tools tested during the cutting process are subjected to grinding. After completion of the grinding operations, fractions with overall dimensions up to 1.0 mm are selected. The resulting crushed and selected powder mass is measured complex indicator of the strength and concentration of acid-base active centers - pH. Measurements are carried out on the device - a universal mode ionomer. EV-74. To do this, take a sample of the prepared crushed carbide structure weighing 0.4 g and place in a potentiometric cell with distilled water with a volume of 25 ml. Its pH should be 6.9-7.0 units. The potentiometric cell is equipped with a magnetic stirrer. Electrodes are also placed in the cell: for example, chloride - silver EVL-1M3 and glass ESL-43-07. The ionomer is connected to a computer, and the electromotive force (emf) data continuously recorded in the cell is displayed. As a result, when measuring, the dependence of the pH of the solution in the cell on time and the concentration of protons adsorbed by the electrode resulting from the dissociation of water molecules into protons and hydroxyl groups is obtained. Dissociation occurs on the surface of the crushed carbide mass (structure) and is initiated by active centers. The concentration of the resulting protons depends on the properties of the surface carbide structure of the ground samples. The magnitude of the emf, and hence the pH, depends on the concentration of protons adsorbed on the surface of the polyoxide powders and the concentration of hydroxyl groups remaining in the water. The higher the concentration of protons adsorbed by the polyoxide surface and the more hydroxyl groups remain in the water, the lower the emf and, correspondingly, the higher the concentration and strength of acidic active sites in the surface polyoxide mass and vice versa.

Analysis of the polyoxide structure lasts from a few seconds to several minutes (usually 2-3 minutes). PH control (predicting the wear resistance of carbide cutting tools, cutting inserts) is carried out according to a sample from the delivered batch in an amount of at least 4-10 samples. After that, a graph of the reference dependence “wear resistance - the value of a complex indicator of the strength and concentration of acid-base centers on the surface of the crushed carbide mass (structure) of cutting tools (plates) - pH” is built. This experimentally obtained dependence is rather well approximated by a linear dependence with a high degree of tightness of the correlation relationship:

,

,

where a _E and in _E are constant coefficients:

,

,

where T _et (min) is the current wear resistance in minutes for carbide cutting tools (inserts) that have been tested from the predicted reference batch of samples;

pH _et (b / c) - the current value (dimensionless value) of the selected initial parameter obtained when controlling the crushed carbide mass (structure) from carbide cutting tools (inserts) from a reference (controlled batch);

Te ₁ and Te ₂ (min) - wear resistance in minutes for two samples of carbide cutting tools (inserts) from the reference batch of carbide products;

pH The pH _{of A1} and _A2 (b / a) - dimensionless quantities selected initial parameter obtained by monitoring the mass of crushed carbide of two samples carbide cutting tools samples (plates) from the reference batch received (sent) products,

Subsequent control of carbide cutting tools of the current batch of delivered products is carried out on the basis of measuring only the selected initial parameter, namely: the value of the complex indicator of the strength and concentration of acid-base centers in the crushed surface carbide mass (structure) of cutting tools (plates) - pH. Based on the obtained reference dependence “wear resistance - pH” and formula (1) above, a wear resistance forecast for the current batch of carbide products is carried out. The predicted wear resistance may be higher or lower than that obtained from benchmark tests. With an increase in the acidity of the ground surface carbide mass (an increase in the complex index of strength and concentration of acid centers - pH), wear resistance increases.

The proposed method allows to predict with high accuracy the wear resistance of carbide (group P) cutting tools when machining steels and alloys that cause intense high-temperature diffusion wear. The selectivity of the method (control over the dominant wear) significantly increases its accuracy.

The drawing shows a graphical correlation dependence of the change in the value of wear resistance on the pH value.

An example of a method for predicting the wear resistance of carbide cutting tools. First, measurements are made on the wear resistance of replaceable carbide cutting inserts of the T15K6 brand, obtained from the reference - previous batch of delivered products. As the processed material, carbon steel 55 was used. The cutting speed during the tests was chosen equal to 180 m / min. The feed rate and depth of cut were respectively 0.23 mm / rev and 1.5 mm. Cutting was carried out without cooling. As a blunting criterion, the wear of the insert along the rear surface, equal to 0.6 mm, was taken. Resistance for samples of 10 pieces of the first reference batch was: 40.0; 40.5; 40.75; 41.5; 41.75; 42.0; 42.5; 43.0; 43.25; 44.0 minutes The average value was 41.925 minutes. Resistance for samples of 10 pieces of the second reference batch was: 36.5; 36.75; 37.25; 37.5; 38.0; 38.5; 39.0; 39.5; 40.0; 40.5 minutes The average value was 38.350 minutes. Then used carbide inserts are subjected to grinding and fractionation. For measurements, a fraction with sizes less than 1.0 mm is selected. After that, weights of 0.4 g were prepared from the powder, they were placed sequentially in the ionomer cell, and the pH was measured. The pH measurement time of the ground mass obtained from each insert was 2 minutes. The arithmetic mean value was determined from the measured, for each, sample of the data array and was taken as a characteristic of the strength and concentration of acid-base centers on the surface of the crushed carbide structure and, accordingly, as an indicator of the wear resistance of carbide cutting tools. The pH values for the first batch of samples of 10 pieces were: 8.55; 8.50; 8.45; 8.40; 8.35; 8.30; 8.25; 8.20; 8.15; 8.10 units The average value was 8.325 units. The pH values for the second batch of samples of 10 pieces amounted to: 9.00; 8.95; 8.90; 8.865; 8.80; 8,735; 8.675; 8.60; 8.55; 8.50 units The average value was equal to 8.760 units. According to the wear resistance of carbide cutting tools and the pH value on the surface of the crushed carbide structure of the samples from the reference batch of samples, we plotted the reference, correlation dependence "wear resistance - pH".

To predict the wear resistance of carbide cutting inserts in the next current, intended for consumption batch of samples, only the value of the complex concentration index and the strength of acid-base centers on the surface of the crushed carbide structure is tested - pH. For samples of ground carbide structure obtained from 10 carbide cutting inserts, the pH was: 8.75 8.65; 8.60; 8.455; 8.45; 8.40; 8.35; 8.30; 8.25; 8.20 units The average value of this value was 8.44 units. Based on the average pH value of the crushed structure obtained from T15K6 carbide cutting inserts (pH cf) of the current batch and formula (1), Tpt (cf) is the average predicted wear resistance of T15K6 carbide cutting inserts for the current batch of delivered products. As a result, the predicted - the current value of wear resistance from calculations for a controlled batch of products amounted to an average of 40.821 min, which

approximately corresponds to the resistance of the reference batch of incisors. When predicting wear resistance for the current batch of carbide cutting tools, there is no need for expensive and time-consuming wear tests conducted on metal cutting machines. The method has a high forecast accuracy. This is due to the close relationship between the properties of hard alloys (wear resistance), the properties of the surface carbide structure of hard alloys and the complex indicator of the concentration and strength of acid-base active centers in the ground surface carbide structure — pH. Due to the comparison of the data on the forecast of wear resistance obtained in accordance with the prototype and the proposed method, as well as as a result of control experimental studies of wear resistance performed in the cutting of carbon steel, it was found that the results obtained in accordance with the prototype differ from the control tests by 15- 20%, while the results obtained by the proposed method differ only by 5-10%.

Thus, the proposed control method - predicting the wear resistance of carbide cutting tools can be used with sufficiently high economic efficiency in enterprises that manufacture and consume carbide products.

Claims (1)

A method for predicting the wear resistance of carbide (group P) cutting tools according to the selected initial parameter, including carrying out benchmark wear tests in the process of cutting materials at an optimum or close cutting speed, testing to change the value of the initial parameter from the properties of the surface ground carbide mass of cutting tools ( plates), the construction of the reference correlation dependence "initial parameter - wear resistance" for specific temperatures anija and heating current statistical control only parameter values starting from the current batch of carbide cutting tools, wear forecast for the current batch of instruments based on the relationship:

where a _e and in _e are constant coefficients:

of them
T _pt (min) - the current wear resistance in minutes for carbide cutting tools (inserts) that have been tested from the forecasted current batch of samples;
pH _pt (b / c) - the current value (dimensionless value) of the selected initial parameter obtained by monitoring the crushed carbide mass (structure) from carbide cutting tools (inserts) from the current controlled batch;
Te ₁ and Te ₂ (min) - wear resistance in minutes for two samples of carbide cutting tools (inserts) from the reference batch of carbide products;
pHe ₁ and pHe ₂ (b / c) are the dimensionless values of the selected initial parameter obtained by controlling the crushed carbide mass from two samples of carbide cutting tools (plates) from a reference batch of received (sent) products, characterized in that, for the purpose of increase the accuracy of predicting wear resistance, as the initial parameter, use the value of a complex indicator of the concentration and strength of acid-base active centers in the crushed surface carbide mass (structure) - pH, with a decrease in which the wear resistance increases.