RU1805018C - Grinding tool with stepped working surface - Google Patents

Abstract

Usage: in the metalworking industry for abrasive processing. The inventive tool is a single or prefabricated abrasive wheel with a stepped working surface, the diameter of each of the subsequent sections of which exceeds the diameter of the previous one and each section is made in the form of a truncated cone, while the smaller base of each of the previous sections is associated with a large base of the subsequent plot along a curve whose radius r is determined by the formula g ЗР / 5, where Р is the size of the abrasive grain of the main fraction of the tool, and forming each of the workers chastkov inclined to the tool axis at an angle «0,017 ° ... 0,14 °. 1 wpp, 2 ill.

Description

The invention relates to the field of abrasive machining, in particular to the design of the working surface of a grinding wheel for centerless continuous grinding. .

The aim of the invention is to increase the productivity and cost-effectiveness of centerless continuous grinding.

Figure 1 shows the proposed tool; Figure 2 shows the construction of a conical shaped element.

An centerless grinding abrasive tool has a working surface consisting of an intake section I. a main metal removal section II and a calibrating part III.

The intake section I and the main metal removal section II have a profile in the form of wedge-shaped elements (hereinafter referred to as thresholds), which are obtained by dressing with a diamond tool on a copy. Each section consists of several thresholds. There are two to three thresholds on the intake section I, depending on the size of the maximum maximum deviation of the diameter of the workpiece. There are 2-15 thresholds in the main metal removal section, depending on the size of the allowance for the operation and the height of the circle. The length, height of the cutting edge and the angle of inclination of the trailing surface of the thresholds depend on the height of the circle and the size of the allowance to be removed.

The calibrating part (II circle-known design.

For more efficient use of the useful peripheral surface of the circle, no exit cone is created. Ensuring a smooth exit of parts from the processing zone is achieved by setting up the machine.

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With centerless continuous grinding, the intake section G is designed to provide unimpeded entry of the parts into the grinding zone and to form a continuous continuous flow, taking into account the fact that the workpieces can have, especially during preliminary processing operations, significant deviations from the nominal size.

The number of thresholds on the fence is 2-3.

The design of the intake section in the form of wedge-shaped thresholds allows you to: reliable grip of parts in circles, creating a favorable mode of self-grinding of the wheel while maintaining edge cutting, removing excess allowances, preparing for grinding in the main section with an allowance of a constant nominal value, which significantly affects the creation of stable cutting conditions and the quality of the grinding process.

To solve these problems, it is sufficient to have, depending on the specific technical conditions, a fence section from 30 to 60 mm long with two to three thresholds.

An increase in the length of the intake section and the number of thresholds on it does not give an additional positive effect.

On the main metal removal site II, the number of wedge-shaped thresholds is 2-15, which create a new multi-edged form of the working area. The number of thresholds is selected depending on the size of the allowance and the height of the circle or set of circles. In the process of centerless grinding, the part passes through the working area between the grinding and driving wheels along their generators. But, unlike the known stepwise generatrix, metal shearing during removal of the allowance is performed by wedge-shaped thresholds, with each threshold having essentially three parts. The first is a leading cutting edge that removes metal. The second is the rear surface, located at an angle to the axis of the circle.

This shape of the threshold is necessary to prevent premature wear of the abrasive grains located behind the grains forming the cutting edge, as well as to prevent the possibility of salting of this area with grinding products.

In this case, the last threshold is combined with the calibrating part of the circle and has a cylindrical shape.

The third part is the radius at the base of the cutting edge, which increases the resistance of abrasive grains to spalling and

volumetric failure as a result of increased cutting forces.

The height of the first threshold and the angle of inclination of the rear surfaces of each of the thresholds,

formed on the working surface of the wheel are selected depending on the specific processing conditions (purpose of the operation, properties of the material being processed, condition of the machine and a number of other circumstances.

However, the height of the first threshold should not be less than 0.03 mm and more than 0.05 mm, and the angles should be less than 0.017 ° and more than 0.14 °. At a lower height of the first threshold

5 and the angles of inclination of the rear surface of the thresholds, the edge cutting effect is lost and the positive effect is reduced.

The limitation of the maximum height and tilt angles is related to the features

0 cutting process by the periphery of a circle of cylindrical outer surfaces. An excessive increase in height and angle is also accompanied by a decrease in the beneficial effect.

5 when calculating the height of the thresholds, it must be borne in mind that the allowance removed in this operation will be equal to their sum.

Due to the multi-edged working zone, the number of working sections increases from o0 to the number of thresholds in the circle.

It is the features of the cutting process by the leading edges that provide the positive effect of using the grinding wheel of the proposed design

5 wedge-shaped thresholds.

The wedge-shaped cutting scheme creates optimal conditions for self-sharpening circles and maintaining high cutting ability in

0 for a long time.

The grinding wheel self-sharpening mode is as follows. The abrasive grain constituting the cutting edge is exposed during operation

5 efforts directed from the side of the workpiece, which tend to tear the grain out of the binder or destroy it in bulk. Bond resistance from the radius side at the base of the cutting edge holds the grain in

0 body of the circle. As the grain becomes blunt, a wear area forms at its apex, which, under the action of the cutting force, collapses superficially, forming new sharp edges.

5 Thus, the grain continues to form a cutting edge and participate in the work to remove the stock from the workpiece. After the wear pad is re-formed, it again collapses to surface, forming sharp edges, etc. The self-sharpening cycles of the abrasive grain are repeated until it is fully activated. After all the grains of the contact arc forming the cutting edge have been worked out, the following abrasive grains come into operation, which form a new cutting edge, shifted in the direction of the longitudinal supply of the part by the grain size of the main fraction of the grinding wheel.

Wear of the cutting edges takes place simultaneously. As a result, the entire cascade of thresholds gradually moves along the generatrix of the circle. Thus, an operating mode is created in which reproduction of the thresholds along the generatrix of the circle and the grinding zone occurs while maintaining edge cutting.

As a result of the combined actions of the above factors, the wear and consumption of the abrasive tool is reduced, the degree of heating of parts in the cutting zone is reduced, the spacer forces causing various kinds of deformation of the system are reduced, the required process power is reduced, the adjustment of machines for forming the working area is greatly simplified, the grinding performance is increased, since it is possible to increase the stock removal in one pass with a constant longitudinal feed, the number of operations per due to the concentration of preliminary and final grinding on one machine, the quality of processing, the constancy and reliability of adjustment during the entire working time are improved, the conditions for the rational use of abrasive tools are created with the maximum effect and saving time on commissioning and adjustment of the machine.

The proposed design can be used on any centerless grinding machine for continuous grinding of any parts.

At the Moscow Automobile Plant named after I.A. Likhachev conducted an experimental study of the new design of the grinding wheel, including in production conditions for the operation of centerless continuous grinding of pivots

knuckle on a centerless grinding machine mod. L-297C2.

As a result of research, it was found that the new design of grinding

A circle with a generatrix in the form of wedge-shaped elements for centerless continuous grinding, in comparison with the stepwise and conical forms of the generators, provides the following positive technical and economic effect, subject to constant technological conditions: the productivity of the process of centerless continuous grinding increases by 1.7 times, the consumption of abrasive

the tool is reduced by two times, the specific energy consumption is reduced by 40%.

Further research on the optimal technological conditions for grinding in relation to the new design of the wheel will allow noBbicnf its effectiveness. Taking into account the obtained technical and economic effect, Moscow Automobile Plant named after I.A. Likhacheva adopted a new design of a grinding wheel with a generatrix in the form of wedge-shaped thresholds for centerless continuous grinding for implementation.

Claims (2)

1. A grinding tool with a stepped working surface, the diameter of each of the subsequent sections of which exceeds the diameter of the previous one, which is so that, in order to increase the cutting ability of the tool, each section is made in the form of a truncated cone, with a smaller base of each previous sections linked to the large base of the subsequent section along a curve whose radius r is determined by the formula g 3 / 5P, where P is the size of the main abrasive grain fractions of the tool. 2. The tool according to claim 1, characterized in that the generatrix of each of the working sections is inclined to the axis of the tool at an angle a of 0.017-0.14 °. Figure 1