SU708199A1 - Method of testing cutting-off disks - Google Patents

Description

(54) METHOD FOR TESTING CUTS CUTS

The invention relates to the field of machine-tool construction and is intended for testing of cutting abrasive wheels. There is a known method of testing cutting wheels, including cutting target blanks fixed on both sides, and measuring process performance indicators 1. The number of cuts, grinding coefficient equal to the area of the cut and the worn part of the circle, the movability of the cutting, is normal and tangential to the components of the cutting force, temperature, degree of burnout, etc. The disadvantage of this is is a person from the fact that it does not allow to quantify diffepentsipovanns o listed vshe- indicators for the periphery and the sides of the circle object of the invention is to eliminate these drawbacks. The goal is achieved by the fact that cutting is performed on two blanks that are installed along the same axis with a gap between the ends of not more than the difference between the height of the circle and the size of the abrasive grain (grain) and these properties are evaluated separately for changes in the values at different values of the gap. With the linear nature of the dependence of the estimated indicators of the cutting process from the active (participating in cutting) the height of the circle, at least two cuts with different gap sizes are enough. In particular, one of them can be made on a single piece, which is equivalent to cutting blanks with a gap between the ends equal to zero. According to this method, the cutting wheels are tested in the following sequence; the solid workpiece is fixed on the foot of the machine and cut. Then, the split blanks are shifted to a gap of less than the difference in the height of the circle and the size of the abrasive grain (grain), fixed and cut. In either case, the process of measuring, for example, the tangential component of the cutting force, power, degree of burnout, etc., is measured during cuttings. p. Depending on the required accuracy of the assessment of the properties of cutting wheels

the cutting is repeated at different gaps between the blanks. The properties of the periphery and the side surfaces of the circle are estimated from the change in the indices of the cutting process at different values of the gap.

 A quantitative assessment of the influence of the properties of the side surfaces of the circle without distortion can be obtained analytically or graphically, for example, by extrapolating the values of one or the other estimated index obtained from two experiments with different gap values, since the dependence of the estimated indicators of the cutting process on the active (participating in cutting) of the cutting wheel height is usually linear. Obviously, an increase in the number of experiments clarifies the desired estimate.

When cutting blanks with a gap in order to avoid bending the circle during the cutting process, the gap should be positioned symmetrically relative to the center plane of the circle.

In this case, the smaller the difference in the height of the circle and the gap between the cut planes of the workpiece, the smaller the distorting influence of the peripheral (cutting) part of the circle on the evaluation of the properties of its side surfaces. However, this difference should not be less than the average size of the abrasive grain in a circle (circle grain), since otherwise the conditions of interaction between the side surfaces of the circle and the walls of the shifted blanks will differ from the conditions of such interaction during normal cutting.

FIG. Figure 1 shows three transitions involving the cutting of workpieces and the measurement of the tangential component C ;: ly of cutting; - FIG. 2 shows the dependence of the tangential and normal forces acting on the workpiece on the difference in the height of the circle and the gap between the workpieces for experimental and serial cutting wheels.

The test of the cutting wheel 1 is carried out when cutting the workpieces 2 with d; 3 of them are on racks of the dynamometer 4. Racks, which are beams of equal resistance, wire conductors 5 are assembled, assembled according to the bridge scheme, and unbalance of this bridge, proportional to the tangential composition; the cutting power, is recorded on the tape of the electronic resistance potentiometer the diagram is not shown)

The dynamometer device is fixed on the table b of the cutting machine.

FIG. Figure 1 shows three transitions, including cutting the workpieces and measuring the tangential component of the cutting force:

 I - when cutting a solid blank, the gap is h О ,, and the difference is the height of the circle: Ha and H and the size of the gap, h is equal to height T) E of the circle H-h 3 mm;

II when cutting blanks separated by 1.5 mm H-h 1.5 mm;

III - when cutting blanks separated by 2.5 mm Hh 0.5 mm.

By this method were tested. cutting wheels D 300 x. 3 x 32 14A 50STZ B5U of mass production with a smooth side surface and D 300 X 3 X 32 14A50STZB5U from an experienced NIN-abrasive fabric with a rough side surface. Circles were tested when cutting blanks with a diameter of 40 mm from steel 2x13 at a cutting speed of 80 m / s and a radial feed of 8 mm / s on an abrasive-cutting machine model 230, equipped with a 5 strain gauge for recording tangential and normal forces on tape recorders -on the workpiece when they are cut. FIG. Figure 2 shows the dependence of tangential 0 (line 1 and 3) and normal (line 2 and 4) forces acting on the workpiece on the difference in the height of the circle and the gap between the workpieces for the experimental (line 1 and 2) and serial 5. (Lines 3, and. 4) cutting wheels.

The true values of the components, depending only on the properties of the side surfaces of the circle, were found by extending (extrapolating) the direct, connecting values of the indicators for different values of the gap between the workpieces, to the intersection with the ordinate axis.

From FIG. 2 it can be seen that a significant part (up to 50%) of the tangential component is хhtsey-, a. consequently, the required power is created by the friction force of the side surfaces of the circle against the walls of the cut. The normal component of the cutting force tends to zero if the size of the gap between the workpieces tends to a height of a circle, since it depends only on the active (participating in cutting) height of the circle and does not depend on the properties of the side, circle surfaces.

The table shows the results of the assessment of cut-off wheels.

D 300 X 3 X 32 14A 50STZB5U. (serial with smooth side surface)

D 300 X 3 X 32 14A 50STZB5U (experienced NIIabraziv with a rough side surface)

The grinding ratio is. the ratio of the sectional area of the cut metal to the area of the worn part of the circle.

The results of the table show that the surface quality of the cut blanks and the durability of the cutting wheels depend on the magnitude of the lateral friction force, which can serve as a criterion for assessing the quality of the cutting wheels.

Using the proposed method for testing cutting wheels allows differentiated quantitative assessment of the cutting and friction properties of the lateral and peripheral surfaces of the circle.

Claims (1)

1. GOST 100110-71. Diamond cutting wheels. ////////// fii o s I-L MM