RU2325259C2 - Finishing method - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: revolving part is processed by abrasive tool fixed in the toolhead. Toolhead is imparted to a circular motion along the surface to be processed in the plane located at the acute angle to the part rotation plane. Abrasive tool in the form of two abrasive sticks is used. Toolhead is fixed at the axis of crank gear keeping one degree of freedom around the centre of this axis.

EFFECT: enhancing the contact area of tool and surface to be processed; enhancing the processing efficiency and quality.

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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 an abrasive tool, mounted in the tool head, making a circular motion along the surface to be machined. The abrasive bar is given oscillating motion along an arc of a circle whose radius is greater than the radius of the workpiece and which is located in the plane of rotation of the part [2].

The disadvantages of this method are the low productivity and quality of processing, since processing with the specified method can be carried out by only one abrasive block, the contact surface of the abrasive tool with the surface being machined is small, and the risks from abrasive grains do not overlap.

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

The problem is solved in that in the known method of finishing machining a rotating part with an abrasive tool fixed in the tool head, including a message to the tool head in circular motion along the surface to be machined, use an abrasive tool in the form of two abrasive bars, the tool head is fixed on the axis of the crank mechanism while maintaining one degree freedom around the center of the mentioned axis, and the circular motion of the tool head is reported in a plane located constant acute angle to the plane of rotation of the items.

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. Since the tool 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 a plane located at an acute angle to the plane of rotation of the part, this ensures the intersection of the patterns on the work surface, which helps to improve the quality of this surface.

The invention is illustrated by drawings, where figure 1 shows a diagram of an implementation of the method of processing the inner ring of the bearing, figure 2 is a section aa to figure 1, figure 3 is a diagram of the method of processing the outer ring of the bearing, figure 4 - section AA to figure 3.

To the part 1 mounted on the spindle of the product (not shown) and rotating around its axis (Figs. 1 and 3), abrasive bars 2 are clamped, fixed in the tool head 3, located at an angle β to the plane of rotation of the part 1 (Fig. 2 and four). The tool head 3 is fixed on the axis 4 of the crank mechanism 5. The tool head is fixed so that it has only one degree of freedom, namely, rotation around the center Og of 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 a plane located at an acute angle β to the plane of rotation of the part 1 (FIGS. 2 and 4), and the bars 2 are attached a complex movement, namely a reciprocating movement with amplitude e at an angle β to the plane of rotation of the part and a periodic turn through an angle ± α. The value of α (figures 1 and 3) depends on the eccentricity e and the distance L between the axes of the crank mechanism 5 and the workpiece 1: α = arciq (e / L).

Due to the reciprocating movement at an acute angle β to the plane of rotation of the part 1 (FIGS. 2 and 4), the intersection of the marks from the abrasive grains on the surface of the part is ensured, which reduces the surface roughness. Due to the periodic turn around the axis of the part by an angle of ± α (Figs. 1 and 3), the bars are run in along the machined surface, which ensures the bars are self-sharpening and their chips and sludge are cleaned from their working surface. This helps to increase the productivity of the process.

Example. Let the rolling track of the inner ring of the ball bearing 176305 be subjected to processing: the diameter of the raceway d = 35 mm, the angle of the plane of movement of the superfinishing head to the plane of rotation of the part is taken equal to β = 20 °, the value of the eccentricity of the crank is e = 1 mm, the rotational speed of the crank is n _k = 500 rpm, the peripheral speed of the part - V = 60 m / min, the width of the raceway - b = 10 mm.

We take abrasive blocks of a rectangular shape. The height of the bar is taken h = 4.9 mm, so that during the oscillation process it slightly protrudes beyond the raceway and guarantees processing along the edges of the surface to be treated. The length of the bar l is chosen, as in the usual superfinishing, corresponding to the equality l≈0.5 · d, where d is the minimum value of the diameter of the processed surface. In the conditions of the example, we take l = 17 mm.

The magnitude of the eccentricity e is selected from the design considerations of the maximum possible, but such that excessive vibrations do not occur in the technological system due to the oscillatory movement of the super-finish head. In most cases, the value of e = 1-2 mm.

The angle of inclination of the plane of motion of the superfinishing head to the plane of rotation of the part is selected from the ratio:

where λ is the allowable value of the oscillations of the bar in the transverse direction of the raceway.

The value of A is determined experimentally based on the prevention of breakage of the bars and due to the prevention of significant distortion of the profile of the treated surface. Approximate values λ = 0.1 ÷ 0.5 mm. For the conditions of the above example, λ = 0.34 mm.

The technical and economic efficiency of the proposed processing method consists in the possibility of increasing the productivity and quality of processing, as well as providing the possibility of processing a complex surface such as an arched surface.

Information sources

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

2. RF patent No. 2227772. Device for superfinishing toroidal surfaces of ball bearing rings. Bull. No. 12 04/27/2004 // Chistyakov A.M., Korolev A.V., Stepanov K.V.

Claims (1)

A method of finishing a rotating part with an abrasive tool fixed in the tool head, comprising a message to the tool head in circular motion along the surface to be machined, characterized in that the tool is used in the form of two abrasive bars, the tool head is fixed on the axis of the crank mechanism while maintaining one degree of freedom around the center of the aforementioned axis, and the circular motion of the tool head is reported in a plane located at an acute angle to the plane axes of rotation of the part.

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