RU2542891C2 - Grinding wheel - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to production of tools and can be used for making of grinding wheels for centreless grinding, circular grinding and internal grinding in single pass. Grinding wheel comprises metal body with working part made of diamond-bearing material applied thereon and including organic or metal binder and diamond grains. Working part (2/3-3/4)B-long section contains diamond grains of hardness increasing in generatrix length and is intended for cutting in the workpiece. Working part (1/3-1/4)B-long section contains diamond grains of equal hardness and serves for finishing. Relationship is given to define hardness of diamond grains at section with increasing hardness.

EFFECT: uniform wear, regular sizes, geometric accuracy, longer life.

1 ex, 2 tbl, 2 dwg

Description

The invention relates to the field of tool industry and can be used in the manufacture of grinding wheels for performing centerless, round and internal grinding operations on the passage.

A grinding wheel is known that contains a variable characteristic of the working surface, consisting in the fact that the coarse-grained sections of the abrasive and the areas located behind them are fine-grained in pairs separated by sections of the abrasive with a lower hardness, and the hardness of the abrasive is selected depending on the hardness of the material being processed (RF Patent No. 2395381, B24D 5 / 14, B24D 7/14, 2008).

The disadvantage of this grinding wheel is that there is a greater likelihood of violating the integrity of the design of the grinding wheel at the junction of the sections, and at different grain sizes on rough and finishing sections, uneven wear of the wheel occurs due to the fact that at the moment of contact large grains are pulled out in the rough sections.

The closest technical solution to the proposed invention is a grinding wheel containing a diamond layer, consisting of side sections and a central section made less wear-resistant (Patent RU 2103154 CI, B24D 5/14, 01/27/1998).

The disadvantages of this solution is the reduction in the resistance of the circles and the accuracy of the machining during diamond centerless grinding of carbide cores.

The technical result, to which the claimed invention is directed, consists in uniform wear of diamond grains in each of the layers, which ultimately increases the life of the wheel.

This technical result is achieved by the fact that in the grinding wheel containing a metal casing with a working part made of diamondiferous material formed from an organic or metal bond with diamond grains, according to the invention, the working part along its generatrix is made with sections having diamond grains of different strengths while the portion of the working part with a length l = (2 / 3-3 / 4) B contains diamond grains, the strength of which increases along the length of the generatrix, and is intended for the cutting process preform, and the portion of the circle of the working length (1 / 3-1 / 4) B is composed of diamond grains of the same strength and for finish grinding the workpiece, the strength of the diamond grains on an area with increasing strength is determined from the relationship

where B is the width of the working layer of the circle;

a = 149.8 ... 29.7 is a coefficient depending on the size of the allowance Δ for grinding in the range (Δ = 0.05 ... 0.5 mm),

b = -0.44 ... -8.5 is a coefficient depending on the diameter d of the workpiece for grinding in the range (d = 1 ... 500 mm),

c = -99.74 ... 9.6 is a coefficient depending on the hardness of the processed material in the range (HRA 80 ... 105).

The invention is illustrated by drawings, where:

- FIG. 1 schematically shows a diamond grinding wheel,

- FIG. 2 shows graphs of dependences of changes in the strength of diamond grains along the length of the generatrix.

The grinding wheel comprises a metal casing 1 with a working part 2 made of a diamond-bearing material deposited on the surface of the casing 1, including an organic or metal binder and diamond grains. In the longitudinal direction, the working part 2 of the circle consists of two sections: section 3 and section 4. Section 3 of the working part 2 of length (2 / 3-3 / 4) B, where B is the width of the working part 2 of the circle, is located on the side of the circle working to plunge. Section 3 contains diamond grains, the strength of which increases along the length of the forming circle from section 4 of the working part 2 of length (1 / 4-1 / 3) B, consisting of diamond grains of the same strength and intended for fine grinding.

At the boundary of sections 3 and 4, the strength of diamond grains is the same, then the strength of diamond grains of section 3 varies along the generatrix of the circle according to

H (l) = a · e ^{b · l} -c, where Η is the indicator characterizing the compressive strength of diamond grains (diamond grade AC (H) from AC2 to AC50); In - the width of the working part 2 circles; l is the distance of the surface of the end face of the working part 2 of the circle working for cutting, to the site with diamonds of the desired strength N; a = 149.8 ... 29.7 is a coefficient depending on the size of the allowance Δ for grinding in the range (Δ = 0.05 ... 0.5 mm); b = -0.44 ... -8.5 is a coefficient depending on the diameter d of the workpiece for grinding in the range (d = 1 ... 500 mm); c = -99.74 ... 9.6 - coefficient depending on the hardness of the processed material in the range (HRA 80 ... 105).

Figure 2 shows the graphs obtained as a result of experiments, reflecting the dependence of H (l) = a · e ^{b · l} -c of the indicator characterizing the strength of diamond grains on the hardness of the processed material (HRA 80 ... 105), the amount of grinding allowance (Δ = 0.05 ... 0.5 mm), the diameter of the workpiece (d = 1 ... 500 mm).

When choosing an indicator characterizing the strength of diamond grains of a grinding wheel for processing workpieces of higher hardness, it is preferable to use charts 1, 2, 3, while processing workpieces of lower hardness - charts 4, 5, 6. The diameter of the workpiece and the size of the allowance removed in one pass affect the curvature of these graphs.

Chart 1 is recommended to be used when grinding grinding billets of hard alloy of maximum hardness (HRA 92-105) with an allowance of Δ = 0.2-0.35 mm and a diameter of d = 150-300 mm.

Schedule 2 is recommended for use when grinding grinding workpieces of maximum hardness (HRA 92-105) with an allowance of Δ = 0.35-0.5 mm and a diameter of d = 300-500 mm.

Chart 3 is recommended to be used when grinding grinding workpieces of maximum hardness (HRA 92-105) with an allowance of Δ = 0.05-0.2 mm and a diameter of d = 1-150 mm.

Chart 4 is recommended to be used when grinding grinding workpieces of minimum hardness (HRA 80-92) with an allowance of Δ = 0.2-0.35 mm and a diameter of d = 150-300 mm.

Graph 5 is recommended to be used when grinding grinding workpieces of minimum hardness (HRA 80-92) with an allowance of Δ = 0.35-0.5 mm and a diameter of d = 300-500 mm.

Graph 6 is recommended for use when grinding grinding workpieces of minimum hardness (HRA 80-92) with an allowance of Δ = 0.05-0.2 mm and a diameter of d = 150-300 mm.

The table shows the recommended coefficients for the parameter values: the hardness of the workpiece (HRA), the allowance for processing Δ, the diameter of the workpiece d.

Coefficient Values

Example 1

When processing a workpiece from a material with a hardness of 88 HRA and a diameter of 20 mm, it is necessary to remove an allowance equal to 0.1 mm by the method of centerless grinding. It is necessary to use a grinding wheel with a diameter of 350 mm and a width of B = 90 mm. Then, according to the table above, the coefficients of the dependence of the distribution of strength of diamond grains in the 3/4 section on the circle width (according to Fig. 1) are set by the following values: a = 29.7, b = -6.7, c = -2.43, e = 2.17828 (e is the mathematical constant, the base of the natural logarithm). These coefficients were derived by approximating the exponential function of the data obtained empirically in the study of the wear resistance of grinding wheels with centerless grinding.

In this case, the dependence takes the form H (l) = 29.7 · 2.77528 ^{-6.7 · l} +2.43. Using this dependence, it is possible to set the diamond grades in layers from l = 0 to l = (3/4) V along the generatrix of the circle, which have the strength determined by this dependence. In this case, the remaining calibrating part of the grinding wheel will consist of diamonds of the same grade with the diamond strength determined at the point of removal from the end of the wheel along the generatrix l = (3/4) V.

Set the layer thickness to 5 mm. Then the calculation of the strength of diamonds for each layer will be performed with a resolution of 5 mm. The table below shows the results of calculating the strength of diamonds in the layers of the grinding wheel, depending on their distance from the end face of the grinding wheel. The strength of diamonds on the calibrating part was 2.67 Newton.

Thus, the claimed combination of essential features set forth in the claims allows for uniform wear of diamond grains in each of the layers, which ultimately increases the life of the wheel.

The analysis of the claimed technical solution for compliance with the conditions of patentability showed that the characteristics indicated in the independent claim are interrelated with each other with the formation of a stable population, unknown at the priority date from the prior art, of the necessary features sufficient to obtain the required synergistic (over-total) technical result.

The properties regulated in the claimed invention by individual features are well known in the art and require no further explanation.

Thus, the above information indicates the fulfillment of the following set of conditions when using the claimed technical solution:

- the object embodying the claimed technical solution, in its implementation is intended for use in the field of tool industry;

- for the claimed object in the form described in the claims, the possibility of its implementation using the above-described in the application materials known from the prior art on the priority date of the means and methods is confirmed;

- the object embodying the claimed technical solution, when implemented, is able to ensure the achievement of the technical result perceived by the applicant.

Therefore, the claimed subject matter meets the requirements of the patentability conditions of “novelty”, “inventive step” and “industrial applicability” under applicable law.

Claims (1)

A grinding wheel comprising a metal casing with a working part made of diamondiferous material formed from an organic or metal bond with diamond grains, characterized in that the working part along its generatrix is made with sections having diamond grains of different strengths, while the working part has a length l = (2 / 3-3 / 4) B contains diamond grains, the strength of which increases along the length of the generatrix, and is intended for the process of cutting into the workpiece, and the section of the working part of the circle with a length of (1 / 3-1 / 4) B consists of lmaznyh grains same strength and for finish grinding the workpiece, the strength of the diamond grains on an area with increasing strength determined from the relationship:
H (l) = a · e ^{b · l} -c, where
B is the width of the working layer of the circle;
a = 149.8 ... 29.7 is a coefficient depending on the size of the allowance Δ for grinding in the range Δ = (0.05 ... 0.5) mm,
b = -0.44 ... -8.5 is a coefficient depending on the diameter d of the workpiece for grinding in the range d = (1 ... 500) mm,
c = -99.74 ... 9.6 is a coefficient depending on the hardness of the processed material in the range of HRA 80 ... 105.

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