SU1629824A1 - Method of measuring cutting toolъs wear during machining of cylindrical surface - Google Patents

Abstract

The invention relates to the processing of metals by cutting, mainly to methods for measuring tool wear. The purpose of the invention is to improve the accuracy of measuring tool wear. The method consists in cutting, then stopping the feed of the cutting tool, stopping the relative rotation of the workpiece after 1-3 turns after stopping the feed , mechanical high-frequency or ultrasonic oscillations are excited in one of the links of the kinematic pair of tool-part in the cutting power in the direction of tangential To determine the amplitude of oscillations, by 10–20%, more than the ham of allowable tool wear, set the frequency, not a multiple of the frequency of another link, measure relative to the velocity V of the workpiece and the tip of the tool’s edge, at the same time, i.ni is measured by the contact area t to each oscillation cycle, and the width of the contact area L- on the back surface is determined (calculated) using the form L, Km 2 or 1C

Description

The invention relates to metal cutting, primarily to methods for measuring the wear of a cutting tool, and can be used to measure the wear of a cutting tool in the automation of metal-cutting equipment.

The purpose of the invention is to improve the accuracy of wear.

FIG. 1 is a diagram illustrating the process of the method, fig. 2 is a block diagram of an apparatus for implementing the method.

The device contains a vibrator I mounted on a machine caliper, a cutting tool 2, a piezoelectric vibration sensor 3 (for example, the IC-313A type with an operating frequency range of 50-40000 Hz), a noise and vibration meter 4 for measuring the relative speed of the machined surface and the top

the cutting tool, the meter 3 in the mode intervals, designed to measure the intervals of the contact time of the surfaces in each measurement cycle, the switching unit 6, the south-digital generator 7 and the control unit 8 (micro computer) connected to the system c) MI1N

The second input of the switching unit is connected to the second output of the measuring 4, the second input of which is connected to the second input of the meter 5, the output of the CPU 9 and the input of the iar 3, with the control unit 8 of the control unit 6, the vibrator and the input i Stem, 9 CNC

The method is carried out in a manner.

The oscillations of the instrument begin at some point O (Fig. 1). At w. / kepi tools in direction. with a% of growth (-Qto rosio / He1 for an hour 1 liter, about time t links processing and south pimento

TO

her su yu

Јъ

the pairs (contact) of the tool part, while point A moves to position A and point B to position A, i.e., each of the set of points of segment AB passes a path equal to the width of the worn area along the rear face h. Upon further movement in the direction of -f-OZ, the pair element breaks, which ensures the discreteness of measurements. The movement is then carried out in the reverse direction -OZ. From this, the length of the segment AB is written in the form

. Vi, a

where h, is the wear width of the contact area on the back surface, mm; V is the relative speed of movement of the machined surface and the tip of the cutting edge of the tool in the cutting plane in the direction of the tangent to the machined surface, mm / s; t is the absolute value of the contact time of the surfaces in each measurement cycle, c.

In accordance with the block diagram (Fig. 2), at the command of carrying out a measurement of wear, the CNC system 9 turns off the tool feed, after 1-3 turns, the workpiece rotates. In this case, chips are removed from the front surface of the tool, and the workpiece and the tool form a fixed contact (Fig. 1). The CNC system 9 starts in block 8 a program for measuring wear, block 8 turns on a vibrator 1, which excites mechanical high-frequency or ultrasonic oscillations of the tool in the cutting plane in the direction of the tangent to the machined surface.

The oscillations of the tool are reported in the cutting plane in the direction of the tangent to the surface to be machined to meet the requirements of fulfilling the principles of inversion that determine the correctness of the measurements, namely: the movement trajectory in the measurement must correspond to the movement trajectory during shaping; the line of action must coincide with the line of measurement (the Abbe principle); the measurement bases must coincide with the working bases (the rule of database unity). The amplitude of oscillations is selected at least 10-20% greater than the allowable tool wear value to ensure that the measurement process is discontinued over a discrete tool wear length along the back surface. The oscillation frequency of the tool is chosen to be not equal to and not a multiple of the natural frequency of oscillation of the part in order to prevent resonance during measurement.

Instrument 1 is fitted with a vibration sensor 3, which is an accelerometer. Mechanical oscillations by means of sensor 3 are converted into an electrical signal, which is then fed to the input of a noise and vibration meter 5, where the signal is amplified, filtered and the constant component of the signal is extracted using

the detection and output receive the value of the relative speed of movement of the machined surface and the tip of the cutting tool, simultaneously allocated a constant component of the signal from measuring 4 noise and choices are fed to the input of the meter 5 time intervals, where the time interval of periodic signals is measured as contact time in each oscillation cycle. A switching unit 6 controlled by a microcomputer,

connects the analog-to-digital converter 7 to the noise and vibration meter 4 and the meter 5 time intervals. Analog-to-digital converter 7 converts analog signals of a 5-time meter and a noise and vibration meter 4 into digital microcomputer codes, which processes the signal according to an algorithm and, depending on the result of the calculations, issues the corresponding command to the CNC system 9.

5 Example. Grind in the centers of the shaft completely. Diameter of shaft mm, length Z 2000 mm. Cutting modes: circumferential linear speed of the surface to be machined (calculated) V 150 m / min; cutting depth / -1.5 mm; feed, 3 mm / rev;

0 cutter through passage T15 Kb, the main given angle, the material being processed - Art. 45. The parameters of the vibration movement of the instrument: the frequency of mechanical high-frequency or ultrasonic vibrations / 20000 Hz, the amplitude of oscillation

5 1.0 mm. The amount of permissible wear / g

0.8 mm.

Claims (1)

Invention Formula The method of measuring the wear of the cutting tool when machining cylindrical surfaces, consisting in cutting, then stopping the feeding of the cutting tool, stopping the relative rotation of the workpiece 1-3 turns after stopping the feeding, exciting mechanical high-frequency or ultrasonic vibrations in one of the links of the kinematic pair instrument part, register mechanical vibrations that have passed through each contact the surface of the tool-part, and determine the degree of wear of the tool, characterized in that, in order to improve the accuracy of determining wear, mechanical high-frequency or ultrasonic vibrations to one of the links (for example, tool) of the kinematic pair of tool-part is reported in the plane of tangency to the machined surface, choose an amplitude of oscillations at least 10-20% more than the value of the allowable tool wear, set a frequency that is not equal and not a multiple of the frequency of another link, measure the relative speed of movement of the machined surface and the tip of the cutting edge of the tool simultaneously measure the absolute value of the contact time of the surfaces during each measurement cycle, and the width of the worn contact pad on the back surface is determined by the formula ft VT where is l; VTf - the width of the worn contact pad on the back surface, mm; the relative speed of movement of the machined surface and the tip of the cutting edge of the tool in the cutting plane in the direction of the tangent to the machined surface, mm / s; the absolute value of the contact time of surfaces in each measurement cycle, p. Cutter Detail 1 2