RU2282527C2 - Finishing method - Google Patents

Abstract

FIELD: machine engineering, possibly finishing parts such races of precision bearing assemblies.

SUBSTANCE: method comprises steps of working rotating part with use of tool head with two blocks; mounting part in shaft of crank mechanisms while providing one freedom degree around center of said shaft; imparting to tool head circular motion in axial plane of part at self-aligning blocks relative to center arranged in symmetry plane of finished surface. Such procedures provide symmetry of finished part profile.

EFFECT: enhanced efficiency, improved quality of finishing part.

2 dwg, 1 ex

Description

The invention relates to mechanical engineering, namely to technological operations of finishing parts such as rings of high-precision bearings.

A known method of finishing, in which the tools are installed around an axis located at an angle to the axis of rotation of the part, and the point of intersection of the axes is combined with the center of symmetry of the profile of the workpiece [1].

The disadvantage of this method is the decrease in productivity and quality, since it is almost impossible to combine the point of intersection of the axes with the point of symmetry of the machined surface, and this causes a "beating" of the tool and distortion of the part profile.

The closest in technical essence and the achieved effect to the proposed (prototype) is a method of finishing machining a rotating part with abrasive bars fixed in the tool head, making a circular motion around a center located in the symmetry plane of the work surface. The specified center is offset from the axis of rotation of the part by a distance depending on the length of the surface to be machined, the desired convexity of the profile and the diameter of the surface to be machined, and the plane of the circular vibrational movement of the head is perpendicular to the axis of the part [2].

The disadvantage of this method is the low productivity and quality of processing, since processing with the specified method can be carried out only by one abrasive bar, and the center of circular motion of the tool head is difficult to combine with the axis of symmetry of the profile, which causes an error in the shape of the part profile.

The task of the invention is to increase productivity and processing quality.

The problem is solved in that in the known method of finishing, including the rotation of the part, use a tool head with two bars, fix it on the axis of the crank mechanism while maintaining one degree of freedom around the center of the mentioned axis and inform the head in a circular motion in the axial plane of the part with self-setting bars relative to the center located in the plane of symmetry of the workpiece.

Since the proposed method of finishing in the tool head placed two abrasive bars, this increases the productivity of the processing and its corrective ability. And since the head is fixed on the axis of the crank mechanism while maintaining one degree of freedom around the center of the mentioned axis and the head is given a circular motion in the axial plane of the part, the bars during processing are self-aligned relative to the center located in the symmetry plane of the surface to be machined, which ensures the symmetry of the profile and thereby improves the quality of processing.

The invention is illustrated by drawings, where figure 1 shows a diagram of an implementation of a method of processing an inner ring of a roller bearing and a side view, figure 2 is a diagram of an implementation of a method of processing an outer ring of a roller bearing.

To the part 1 mounted on the spindle of the product (not shown) and rotating around its axis (FIGS. 1, 2), abrasive bars 2 are clamped in the tool head 3. The tool head 3 is fixed on the axis 4 of the crank mechanism 5. Fastening the tool head carried out in such a way that it had only one degree of freedom, namely, rotation around the center of the Og axis 4.

When the crank mechanism 5 is rotated, the center Og of the axis 4 rotates along the radius e. Thus, the upper part of the tool head 3 is informed of a circular oscillatory movement in the axial plane of part 1 (Fig. 2), and the bars are given a complex movement, namely, reciprocating movement with amplitude e along the axis of the part and periodic rotation by an angle ± α relative to the axis of the part.

Due to the reciprocating movement along the axis of the part, the bars are self-sharpening, and their chips and sludge are cleaned. This helps to increase the productivity of the process. Due to the periodic turn around the axis of the part, an increased removal of material occurs along the edges of the track and a convex profile is formed. But unlike other known methods of superfinishing in this method, the abrasive bars themselves are set relative to the symmetry point of the profile. This ensures a symmetrical profile, which is an important indicator of quality.

The proposed method can be used for processing external and internal surfaces of various shapes. So, figure 1 shows the processing circuit of the inner ring of the roller bearing, and figure 2 - the outer ring of the roller bearing.

Example. Let the rolling track of the inner ring of the roller bearing 42305 be subjected to processing: the diameter of the raceway D = 35 mm, the track height L _d = 1 mm, the distance between the sides L _b = 9 mm, the diameter of the sides D _b = 39 mm, the distance of the axis of rotation of the crank to the center of symmetry raceways L = 45 mm.

The height of the bar should be B≥L _d . We accept B = 7 mm.

If the workpiece has at least one side, restricting the movement of the bar, so that the bar during processing does not touch the side, its amplitude of reciprocating movements should be:

On the other hand, in order to prevent the bars of the bearing from touching the bearing flanges, the angle of inclination during circular movement of the head should not exceed a value determined from the equality:

Where

.

.

Usually e <0.1L. In this case, equality (2) with an error of less than 10% can be simplified:

Since the amplitude A of the reciprocating movements of the bars and the angle of their inclination α depends on the radius of the circular motion of the head, the value of this radius is limited by the inequalities determined from (1) and (3):

e≤0.5 (L _b -B);

From the first inequality (4) we find e≤1 mm, from the second inequality e≤2.3 mm. Accept e = 1 mm.

To determine the radius of the circular motion of the head when processing the outer rings, formulas similar to formula (4) are used, only the diameter of the raceway should be substituted for the side diameter in the denominator of the second formula:

e≤0.5 (L _b -B);

And one more peculiarity of processing the outer rings should be taken into account: the height of the bar B should be taken 5-15% more than the width of the track:

For example, let the outer ring of the bearing 42305 be machined. The geometrical parameters of this part are the same as the inner ring, except for the diameter of the raceway, which is D = 53 mm.

From formula (6) we obtain:

B = 7.35-8.05 mm.

We accept B = 8 mm.

By the formulas (5) we determine:

e≤0.5 (9-8) = 0.5 mm;

.

.

Accept e = 0.5 mm.

If the workpiece does not have sides, then you still need to use the proposed methodology for calculating the rational processing parameters, taking in the calculations:

where D is the diameter of the raceway of the outer and inner rings.

Equality (7) allows you to limit the height of the bar. If the bars are too high, then the ends of the bar may not take part in the work. And this leads to the fact that with a certain wear of the working part, the ends of the bars rest on the unprocessed surface of the parts and make further processing impossible.

The technical and economic efficiency of the proposed processing method consists in the possibility of efficiently forming a smooth convex symmetrical profile of the workpiece surface on the bar processing operation.

Information sources:

1. RF patent No. 1706134. The method of finishing. // Korolev A.V., Davidenko O.Yu., Chistyakov A.M.

2. RF patent No. 2137582. The method of finishing // Korolev A.V., Korotkov P.Ya., Astashkin A.V.

Claims (1)

The finishing method, including the rotation of the part and the use of the tool head, characterized in that the tool head is used with two bars, fix it on the axis of the crank mechanism while maintaining one degree of freedom around the center of the axis and inform the head in a circular motion in the axial plane of the part with the bars self-adjusting relative to the center located in the plane of symmetry of the workpiece.

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