RU1811986C - Method for controlling part cutting - Google Patents

Abstract

Usage: metal cutting. SUMMARY OF THE INVENTION: preprocessing a reference part with a reference tool. The main component of the cutting force and the electrical conductivity of the tool-part contact are measured. The value of the optimal cutting speed is determined taking into account the ratios of the main component of the cutting force and the values of the electrical conductivity of the tool-component contact obtained by pre-processing the real part.

Description

FIELD OF THE INVENTION This invention relates to the processing of metals by cutting tools with electrically conductive materials.

The purpose of the invention is to improve accuracy.

The essence of the method is as follows.

It is known that when cutting, it is advisable to maintain the optimal temperature treatment. Currently, the only process-acceptable method of measuring temperature in the cutting zone is the natural tool-part thermocouple method. However, in view of the variation in the specific thermoEMF of the tool material, the same temperature values in the cutting zone may correspond to significantly different thermoEMF values of the natural tool-component thermocouple. In this regard, to ensure the necessary measurement accuracy

temperature in the cutting zone, calibration of each tool is necessary; Known methods of calibration either have low accuracy or high complexity, which limits the use of these methods in a production environment.

At the same time, it is known that with increasing both the cutting depth and the hardness of the material being processed, the temperature in the cutting zone 0 and the main component of the cutting force PZ increase. In this case, the dependences in f (t, HB), (t, HB) (t, HB) for fixed values of the cutting speed V, feed S, wear and geometry elements of the cutting part of the tool can be represented as: dependences in f (t , HB), Pz f (t, HB) and G f (t, HB) at fixed values of cutting speed V, feed S, wear and geometry elements of the cutting part of the tool can be. . presented as:

00

WITH

with

Yu

00

about

in 0dggviv

OL

P2 CptZpHBWp G CG tZG

(2)

(3)

Substituting the cutting depth t from the expression (3) and the hardness And In from the expression (2) in (1) allows to obtain:

0 (4)

(w # Ziy () -wfl / wp С С $ Сс Wed

Z 2B / 2.Q - (W 9Zp / Zfl / Vp), W W0 / Wp,

The temperature of the cold ends of the natural thermocouple is neglected (which is quite acceptable when processing under conditions of abundant cooling of the cutting zone), and the nonlinearity of the specific differential thermoEMF is about. natural thermocouple tool-part, (which in most cases is permissible), the relationship between the thermopower of the natural thermolar and the cutting temperature will be determined by the expression:

E av

(5)

When test cutting a reference workpiece with a reference tool at the optimum cutting speed of thermoelectric power of a natural thermocouple and taking into account expression (4), it is determined by the dependence:

G (6)

When test cutting a workpiece with an unknown allowance and hardness with a tool of this size

Yog "i.

where from

o E./ (With PzT GF)

where Oe, a is the specific differential thermoEMF of a natural thermocouple during trial cutting, respectively, of a reference workpiece and a workpiece with unknown allowance and hardness of the ith tool, and b0, $ is the temperature in the cutting zone during trial cutting, respectively, of a reference workpiece and workpiece with unknown allowance and hardness i tool

Pz3. PZI are the main components of the cutting force during test cutting, respectively, of the reference workpiece and the workpiece with unknown allowance and hardness of the 1st tool, Gs, Gi are the electrical conductivities of the tool-part contact when test cutting, respectively, of the reference workpiece and workpiece with unknown allowance and hardness of the ith tool. The optimal value of thermopower during test cutting of a workpiece with an unknown allowance of the ith tool will be determined by the expression;

fifteen

E0 | a # about.

(9)

Taking into account that b0 - C Pzl Gz, and a is determined by expression (8), after substituting 2 in expression (9) we get:

, w

(PZ3 / PZi) w (G8 / Gi)

(YU)

5

0

0

5

0

5

In order to exclude the influence on the accuracy, non-stationarity of the machining allowance, for example, in the form of non-circularity of the workpiece during turning, and the hardness of the processed material, for example, along the cutting depth, the EI, PZI and Gi values used in expression (9) should be measured in the same same fixed point in time

Thus, the optimal value of the thermoelectric power of a natural tool-component thermocouple can be determined by 5 test cutting of a workpiece with variable cutting depth and hardness according to the ratios of the main component of the cutting force and the ED of the CID measured during test cutting of the reference workpiece by the reference tool to the main component cutting force and EP ECF measured during test cutting of a workpiece with variable cutting depth and YsepflOCTbio.

The method is carried out as follows.

For each pair of tool and work materials, according to known resistance models or experimentally, for example, by conducting persistent studies, the dependence of the optimum cutting speed on the geometry element of the cutting part of the tool, feed and cutting depth is determined. One (reference) tool of each size (lead-through, scoring, right, left, etc.) with a fixed wear of the tool (expediently sharpened), test cutting of the reference workpiece with a fixed hardness and fixed values of feed, cutting depth and optimum cutting speed. The reference blank may generally not correspond to the geometric shape of the workpieces. In this case, the reference values of the main component of the cutting force Pz3 and EPKID G3 are measured and stored. The reference values of the Pz3 force and the EC of the KID Ce can also be calculated using models obtained by conducting short-term tests.

Under production conditions, trial cut sections are allocated for each tool size. When the 1st tool comes into operation, for example, as a result of replacing a worn tool in the test cutting section of a workpiece with unknown hardness and machining allowance, the cutting modes, with the exception of the cutting depth, are maintained the same as in the test cutting of the reference workpiece. In this case, at a fixed time instant, the instantaneous values of the main component of the cutting force PZI, EP KID GI and thermopower EI are measured and stored. The thermopower Ei measured in this way is adjusted depending on the values of the ratios Pz3 / Pzi and Gs / Gi, for example, in accordance with expression (9) and the adjusted value is taken as the optimal one.

As shown by the results of experimental studies, when processing heat-resistant alloys based on nickel, high-strength and carbon steels, the value of the exponent W in expression (9) lies within t.,. 3, and Z - 1 ... 5. For example, for structural steels Zp-1, Zfc 0.1, 35. , 75, .6. At the same time, 97; ,14.

Thus, the proposed method in comparison with the prototype allows

5

0

5

0

5

0

to increase the accuracy of determining the optimal thermoelectric power of a natural tool-component thermocouple, since nonstationary cutting depth and hardness of the processed material are taken into account through the values of the main component of the cutting force PZ and EP KID G.

Information about the optimal value of the thermopower can be used to adjust the cutting speed or to assign a stabilized thermopower value in automatic control systems of the cutting temperature. An increase in the accuracy of stabilization of the temperature regime makes it possible to improve the quality characteristics of the surface layer of the manufactured parts, increase the productivity, and reduce the cost of processing.

Claims (1)

The claims A method for controlling the processing of a part by cutting, including pre-processing the part, determining the thermopower value and assigning the optimum cutting speed from the measured thermopower values, characterized in that, in order to increase the accuracy of processing, the reference part is pretreated with a reference tool, measured. in this case, the value of the main component of the cutting force and the electrical conductivity of the tool-component contact, and the value of the optimal cutting speed, are determined by the corresponding them having regard to the relations constituting the main cutting force guide value and electric conductivity values of the contact-part tool obtained by pretreatment with the real part.