SU963844A2 - Elastic abrasive wheel - Google Patents

Description

(54) ELASTIC ABRASIVE CIRCLE

The invention relates to the manufacture of an abrasive tool.

According to the main author. St. No. 774935 is known for an elastic abrasive wheel, comprising a body and an abrasive carrier coating, an elastic base with non-through holes of variable cross section, with a depth of 1 / 3-1.6, the height of the circle on the end surfaces arranged evenly with a circular pitch of 1.5- 3 times less than the ratio of the maximum allowable strength conditions for the circumferential speed of the circle to the frequency of free flexural oscillations of the circle on the spindle, which makes it possible to increase the vibration resistance of the machining process by suppressing the self-oscillations arising during grinding curvature with a frequency close to the lowest frequency of free oscillations of the elements of the elastic system of AIDS. S. 1.

The disadvantage of this circle is the low operational stability when using it on machines with varying degrees of wear, especially on machines that differ in design and parameters of the elastic system, and therefore; with different stiffness and frequencies

free oscillations of elements of the elastic system, as well as in the processing of parts with unequal mass and rigidity. The limited area of stability, in which there is an effective suppression of self-oscillations and, consequently, a limited area of use of a known circle, is explained by the fact that

10, during the grinding process, the parametric oscillations are insufficient in intensity and shape to suppress auto-oscillations with frequencies in the range 1.5 times lower than the often 15 free bending vibrations of the grinding wheel on the spindle.

The purpose of the invention is to expand the technological capabilities of grinding by expanding the area of vibg

20 robustness of processing and, thereby, increasing the stability of the tool’s operating quality.

This goal is achieved by the fact that it is in an elastic base between periodically located openings with a circumferential pitch.

where N is the maximum allowable strength condition; circle speed is circumferential; R - the frequency of free bending vibrations

jKpyra on the spindle, K - 1.5-3 is the inverse proportionality coefficient, additional holes are made inside the periodically repeating step with a variable angular step varying with a constant ratio of the step of adjacent holes τfj. wi

Ty, equal

f irC-1, Z ---)

Where

P); and - natural numbers.

The radial displacement for additional holes from the center of the circle, according to section B, and the depth of the holes / fe may vary in the circumferential direction depending on

 ili ± ne.-J21 ЛЯ. / Si -hi

FIG. 1 shows an abrasive wheel; in fig. 2 - section aa of FIG. ka fig. 3 - the crown of the abrasive wheel; in figo 4 - section b-b of fig. 3

The elastic abrasive wheel comprises a body 1 of solid material, for example, a textolite, and an abrasive carrier coating 2, an elastic base 3, for example, of rubber with a modulus of elasticity of 10-90 kg / cm. In an elastic base, N periodically repeated orifices of variable cross section, for example conical, are made with a circumferential pitch less than 1.5-3 times the ratio of the maximum allowable wheel strength conditions, the circumferential speed V to the frequency P of free and flexural vibrations of the circle on the spindle. District step C corresponds to the post n- ... -Sit

Ny angular step T. Z-holes with variable angular pitch H changes the adjacent holes by the value of

. J2l

O) If. - and

where 1 l, 2, ..., z + 1; rKljM - natural numbers.

The magnitude of each angular pitch i. Can be determined as follows.

From (1) it is obvious that with Z additional holes x ratios of corner steps

 - Hz

 z from where follow equalities

...

), S i - n | vn4 a.i VHV- ...- zHImVi (2)

From (1) and (2) we find that

- (

Considering that

.. ,,, .-- Vo, (b)

M hi.yi (n | vnf 4

t J. 4 T |

The angular step if of that extra-. hole is defined by the expression

U..U / JLvtMH,. ) At “-I (and / m.)

Thus, by the formulas (W), C) and (5), the value of any angular step of an additional adjacent hole can be quantified.

For example, with an elastic base, six conical holes are made with an angular step fc БО. Inside this corner. the pitch is made with additional holes arranged according to dependence (1) with a variable angular shaft: gom (see Fig. 1) V 25 19; "f 1943, 14" 53.

Holes located with a constant angular pitch are shifted from the periphery of the circle to a constant value in the range of 3-6 mm. The radial displacement fiiR (see Fig. 3) of the additional holes is made re-sized and varies in the circumferential direction 1 and by the amount Aft connected to the adjacent holes by the dependence

n At. THIS & R may change i. 5 in the range of 2 to 10 mm.

The depth ii of the holes is made at 1 / 3-1 / 6 of the height of the circle and is chosen close to the value of the axial feed of the circle, for example equal to 1 / 3-1 / 6 of the height of the circle per revolution of the part during circular grinding. The depth of the additional holes may be variable and vary in the circumferential direction of the adjacent holes with the corresponding

For example, the circle has VVA v

height H 32 mm, + 1 10.7; m 8 and l - 6 mm.

Within the angular pitch YO between the holes with the same cross-sectional area S along the ends of the circle, the additional openings can be made with a cross-sectional area varying in

district direction on dependentTMSiti. .

For example, made KoI 54 and. Nose holes with a diameter at the ends of the circle cf - 1 20, .4 15.5 and 10.8 mm.

.-t

The present invention provides an elastic part of a circle with a constant modulus of elasticity in the middle part of the periphery of the circle and periodically varying amplitude contact stiffness, for example, up to two times in the circumferential direction at the ends of the circle, as well as variable modulation of the contact stiffness of the elastic OCHOKJ in adjacent holes. In the direction of the axis of the circle, the amplitude of the modulation of the contact stiffness decreases to zero in the middle part of the circle. A change in the variable angular pitch fi between the extras NOR4 and the adjacent apertures according to the dependence of r provides possible. the modulus of contact hard modulation.

These elastic bases 3 circles when processing at several harmonics. At the same time, the amplitude of the modulation by each of the harmonics can be provided with the desired value either by changing the radial displacement of the HF from the holes with the same cross-sectional area, or by changing the cross-sectional area of the 5 holes, or by changing their depth, related. .

.Ri.5jv. jjiiij No Si TiT

at the moment of contact of the material being processed with a part of the circle that does not have holes in the elastic base, there is little contact deformation, intense removal of material and an increase in processing power. During the contact of the processed material with the area of the circle with a hole and low rigidity of the elastic base, the edge of the periphery of the cutting surface is pressed and the removal rate of the material decreases and the treatment force decreases.

When grinding a wheel with a circumferential working speed p, which is 1.5 times lower than the speed V, allowed by the strength conditions of the tool, variable forces and parametric oscillations of the periphery of the parts of the circle with a frequency w and; with a wide set of multiple frequencies, (-1,2,3, ...), due to the variable angular pitch of the additional holes in the elastic base.

,

Due to the fact that - dr, pair: metric oscillations on the first

harmonics, occurring at a frequency a) —which is greater than the frequency P of free bending oscillations, suppress self-oscillations at the first harmonic,

11e occurs as the tool becomes blunt, thereby increasing stability.

A significant expansion of the area of stability and the suppression of self-oscillations during grinding with an elastic circle of the proposed construction occurs when Gyy and the frequency W (.5-b) P-.

The parameter of the oscillations on the first harmonic is up to 1.5 times the frequency of free flexural oscillations of the circle on the spindle. The subsequent decrease in step C and an increase in the frequency of the Parameter oscillations at the first harmonic leads to the lack of

expansion of the sustainability of the process.

Making additional holes with variable angular pitch W,

the angular pitch variable in dependence on the i $ -mixing holes with a constant обуслов galm determines parametric oscillations with a wide set of multiple frequencies). By

on the one hand, the level of parametric oscillations at any specified Kvtjf frequency decreases, and on the other hand, the frequency range of free bending oscillations in which the suppression of self-oscillations on the first and subsequent harmonics occurs and the vibration resistance increases when grinding parts of different mass increases. on machines of different designs with

different amplitude-phase frequency characteristics of the elements of the elastic system of the machine; moreover, control of the amplitudes of parametric oscillations with frequencies fv w according to any law is provided due to the reshaping DC of additional holes with the same cross-sectional area or changing the depth ti of the holes,

by changing the area S of their cross section by a constant part equal to the ratio of natural numbers) and.

In contrast to the known elastic grinding wheel, parametric multi-frequency oscillations of small amplitude arising from the processing with the proposed tool increase stability by suppressing self-oscillations in a wide frequency range at the first and subsequent harmonics and expanding the technological capabilities of processing while improving quality treated surface and durability

Claims (1)

65 tools. Improving the operational quality and expanding the technological capabilities of processing the range of the proposed design is also confirmed by its operational tests. In the grinding process, the proposed tool does not observe auto-oscillations when grinding parts of different stiffness, decreases the level of parametric oscillations due to the variability of the contact stiffness, and reduces the roughness of the treated surface. Increasing modes of 1.7 p per when processing parts of different rigidity does not reduce the resistance of the abrasive belt on the wheel. Claims 1. Elastic abrasive wheel according to ed. St. 774935, characterized in that, in order to expand the technological capabilities of the tool, it also has non-through holes with a variable angular pitch associated with the adjacent holes Φ iitL-J L, where n and W are natural fi and numbers. 2, Circle POP.1, characterized in that the radial offset of the additional holes from the center of the circle is made variable and varies in the cfkpyKHOM direction by the value of LN associated with the adjacent holes by the dependence M1 .-. L 3. The circle of pop. 1, which differs from the fact that the area 5 of the cross section of the additional holes at the ends of the circle and their depth -Vi is variable and varies in the circumferential direction by an amount related to the adjacent holes depending. Joi + i-J L S-i Vi and Sources of Information. taken into account during the examination 1. USSR Copyright Certificate № 774935, cl. B 24 O 13/00, 1978. - / 1 1 g j-fffff F1 / g.2 fug. four