RU2230649C1 - Method for combination type finishing - Google Patents

Abstract

FIELD: combination type working of metals by cutting, possibly finishing surfaces of precision machine parts made of materials having trend for flaw occurring such as burnouts and micro cracking.

SUBSTANCE: method comprises steps of imparting to blank and to tool feed motion; using combination type tool including grinding wheel and shell mounted on mandrel in the same axis as grinding wheel and designed for working metallic surfaces by means of balls. Fastening members are in the form of tapered washers whose total number is equal to four, two washers on each end of tool. Such fastening system provides axially shifted cutting layer and mounting of grinding wheel and shell by inclination angle relative to plane normal to lengthwise axis. It provides possibility for gradual regulation of amplitude of tool oscillation due to changing inclination angle of shell and grinding wheel.

EFFECT: enlarged manufacturing possibilities of process, enhanced quality, accuracy and efficiency of working.

2 cl, 6 dwg, 1 ex

Description

The invention relates to combined processing of metals by cutting, namely grinding and surface-plastic shock-pulse deformation, and can be used for finishing, surface treatment of surfaces of precision machine parts from materials prone to defect formation in the form of burns and microcracks.

There is a method of finishing surfaces with deforming balls and a device for its implementation, made in the form of a housing and mounted on pins with the possibility of rotation in the drum casing with sockets for balls, while the rotation drive is connected to one of the pins, and the device casing is located on ball bearings for displacement [1].

The disadvantages of the known method and device are the need for pre-finishing before finishing surface plastic deformation; limited use only for flat surfaces; drive power loss during surface treatment with increased microroughness; there is wear of the balls on the nests and noise during operation of the device - all this reduces the productivity, accuracy and quality of the processing process.

Closest to the invention is a method for finishing the finishing of the internal surfaces of machine parts and a tool for its implementation, made in the form of a grinding wheel and coaxially mounted with a stationary rolling mill, in a closed creek of which deforming elements are placed next to each other, while it is possible to change angle of inclination of the circle [2].

The known method and tool have significant disadvantages: design complexity and large overall dimensions, requiring expensive modernization of the equipment used; limited use only for internal surfaces; drive power loss during surface treatment with increased microroughness; there is wear of the balls on the nests and noise during operation of the device - all this reduces the productivity, accuracy and quality of the processing process.

The objective of the invention is noise absorption, reducing balls wear, reducing drive power losses, as well as expanding the technological capabilities of the method and tool by providing periodic, combined and sequential exposure of the machined surface to rotation without intermittent grinding before pulse-impact plastic deformation with axially-shifted working surface, allowing to improve quality and accuracy, reduce the complexity of processing and tool consumption and increase production oditelnost.

This is achieved using the proposed method of combined finishing of surfaces of revolution, in which the workpiece and the combined tool with a grinding wheel located in it and the shells with working elements report rotational movements and a feed movement along the surface to be machined, the combined tool being taken with an axial displacement in the direction of longitudinal feeding the working layer of the grinding wheel and coaxially mounted on the mandrel of the shell having deformations as working elements balloons, while the fastening elements of the combined tool are made in the form of oblique washers in the amount of four pieces, two from each end of the tool to provide an axially offset cutting layer by setting the circle and the shell at an angle to a plane perpendicular to the longitudinal axis, with the possibility of smooth regulation of the amplitude oscillations by changing the angle of inclination of the circle and the shell.

In addition, the shell assembly for treating metal surfaces with balls contains left and right covers, peripherally connected by an elastic shell in which nests for balls are made, each socket consisting of a tube with rolled ends, in which the ball freely moves, while between the covers placed a set of spacer washers, the total height of which is not less than the height of the elastic shell.

Figure 1 schematically depicts the proposed method of combined finishing and implements its design of a combined tool, rotated to a maximum angle α, with a new grinding wheel; figure 2 - design of a combined tool with a maximum worn grinding wheel, rotated by a minimum angle α = 0; figure 3 is a section aa in figure 1; figure 4 is a possible setup, the combined tool is rotated to a minimum angle α = 0; figure 5 is a more technologically advanced for assembly version of the design of the right cover; figure 6 is a possible setup of a combined tool with a new grinding wheel rotated to a maximum angle α.

The proposed method for combined finishing of surfaces of revolution consists in the fact that the workpiece and the combined tool with a grinding wheel 1 located therein with its fastening elements on the mandrel 2 and a casing assembly 3 coaxially mounted with the circle, rotational movements and feed movement are reported with working elements along the processed surface. The combined tool comprises a grinding wheel 1 for preliminary finishing and a shell 3 assembly for the final processing of metal surfaces by impact plastic deformation by balls.

The fastening elements of the tool are made in the form of oblique washers 4 in the amount of four pieces, two from each end of the combined tool to provide an axially offset cutting layer by setting the circle 1 and the shell assembly 3 at an angle to a plane perpendicular to the longitudinal axis, with the possibility of smooth regulation of the amplitude oscillations by changing the angle of inclination of the circle 1 and the shell assembly 3. The spacer washer 5 and nut 6 are also fasteners and are used for reliable installation of components of the combined tool ume on the mandrel 2.

The shell assembly 3 for treating metal surfaces with balls contains a left 7 and a right 8 cover, peripherally connected by an elastic shell 9, in which nests for balls 10 are made, each socket consisting of a tube 11 with rolled ends, in which the ball 10 freely moves.

To ensure the state of "expansion" of the elastic shell 9, which is attached by known methods, for example, vulcanization or glued to the ends of the covers 7 and 8, between the covers there is a set of spacer washers 12, the total height of which is not less than the height of the elastic shell 9.

To reduce drive power losses, as well as to reduce wear on the sockets 11 and balls 10, the axis 13 of each socket 11 is located at an angle β to a straight line 14 connecting the longitudinal axis of the mandrel 2 with the center of the outlet opening of the socket 11.

The angle β depends on the diameter of the tool, because select it so that at the moment of contact of the ball 10 with the surface to be machined, the axis 13 of each socket 11 is directed at right angles to it when processing flat surfaces or normal to the tangent when processing surfaces of revolution.

For a more technologically advanced assembly and adjusting the tension of the shell 9, a design option for the right cover is provided (Fig. 5), which is made integral and consisting of a ring 15, a flange 16 connected by screws 17.

The work of the shell Assembly 3 with the deforming balls 10 is as follows. It can be installed obliquely to the axis of rotation (FIGS. 1 and 2) with oscillation of the working surface in order to increase the captured processing zone and increase productivity, or it can be installed traditionally (FIGS. 4 and 6) without oscillation.

Under the action of centrifugal forces arising from the rotation of the shell 9, the balls 10 protrude above its periphery. By setting the longitudinal feed to the tool and the rotation of the workpiece in the case of processing bodies of revolution, you can process surfaces of any given size. In the case of processing flat surfaces, the combined tool is mounted on the spindle of a surface grinding machine and machined as with traditional flat grinding by the periphery of a circle.

Work on the proposed method with a combined tool is as follows.

A workpiece such as a body of revolution is clamped in the chuck of the grinding machine, and the combined tool is clamped on the mandrel of the grinding head.

The grinding wheel 1, in contact with the peripheral axially displaced cutting layer of the grinding wheel, installed at an angle to the axis of rotation, with the workpiece surface, removes the established allowance, and the deformation balls 10, protruding above the periphery of the shell 9, strike the workpiece. In this case, a final microprofile of regular roughness is obtained with a relatively small number of working balls 10.

The axially displaced cutting layer of the grinding wheel 1 eliminates the formation of burns on the processing surface, and the deforming balls ensure the continuity of plastic deformation of the surface of the product, which eliminates vibrations and vibrations of the wheel 1 and reduces the roughness of the treated surface.

As the grinding wheel 1 wears out, it decreases in diameter and it is necessary to restore its original size. To adjust the size of the outer diameter in the radial direction and restore the original size, rotate the grinding wheel in the plane passing through the axis of rotation by the value of the angle α _t determined by the formula

α _t = arc cos D / (D + 2t),

where D is the outer diameter of the combined tool, mm;

t is the thickness of the removed abrasive layer for one edit circle, mm;

moreover, the maximum angle of inclination is prescribed from the condition of the continuous grinding zone at one revolution of the circle, determined by the formula

α _max = arc sin (H / D),

where H is the height of the grinding wheel.

As the grinding wheel wears out and the angle of inclination decreases with each subsequent straightening, the grinding width will decrease from N _max to N (Fig. 2). Upon reaching the position of the angle of inclination α = 0 circle further restoration of its outer diameter D is impossible and it is necessary to replace the worn circle with a new one.

Example. On the internal grinding machine mod. ZK228V was simultaneously grinded and processed by pulse-impact plastic deformation through hole with a diameter of 60 N7 ^(+0.03) mm and a length of 60 mm. The roughness parameter of the treated surface is Ra = 0.63 μm. The allowance on the side of 0.2 mm. The workpiece material is steel 45, hardened, hardness HRC45. The machine is equipped with a device for active control of workpieces. The grinding wheel recommended for this steel, grade 24A25PS25K8A, with a diameter of 50 mm, a height of 16 mm, a hole diameter of 13 mm, type PP GOST 2424-83. The rotation frequency of the circle was taken 13000 min ^-1 , the rotation frequency of the workpiece is 200 min ^-1 . A longitudinal feed was set at 5390 mm / min. Cross feed - 0.006 mm / dv.hod (which is 1.5 times more than with traditional grinding). The angle of inclination of the new grinding wheel α = 10 °. The amplitude in this case was 8 mm, and H _max = 24 mm. The shell is rubber, 15 mm thick, 25 mm high, nests for balls in the form of a tube made of 12X17 steel with an outer diameter of 10 mm, a wall thickness of 0.5 mm, and standard manufacturing accuracy is a pipe 10 × 0.5-12X17 GOST 9941-72 . Balls with a diameter of 8.73 mm (from bearing No. 110 GOST 8338-75) are inserted into the nests - tubes with a length of 15 mm. The ends of the tubes are rolled. The angle β of the installation of the socket to the straight line connecting the longitudinal axis of the mandrel with the center of the outlet of the socket was taken equal to β = 8 °.

To ensure the required quality and dimensional accuracy of processing, the main time was 0.65 min, which is 2.4 times faster than with separate grinding and impact-plastic deformation.

The use of this method of combined finishing allows to exclude the operation of semi-grinding due to the improvement of surface roughness by 1-2 grades and to obtain a processed riveted wear-resistant surface.

The proposed method and the combined tool, which implements it and consisting of a grinding wheel and a shell with deforming balls, is characterized by sound absorption due to the use of an elastic shell, reduced wear of the balls and reduced drive power losses.

The proposed method extends technological capabilities by providing periodic, combined and sequential exposure of the machined surface to rotation of non-sand intermittent grinding before impulse-impact plastic deformation with an axially-shifted working surface.

The combined method allows to improve quality and accuracy, reduce the complexity of processing and tool consumption and increase productivity.

Sources of information

1. A. p. USSR 667391, MKI V 24 V 39/04. A device for treating metal surfaces with balls. Zhebelev Yu.K. and Rubin I.L. Application No. 2564489 / 25-08, declared 01/06/78, publ. 06/15/79. Bull. Number 22.

2. RF patent 2100177, MKI B 24 V 45/00, 39/02, B 24 D 5/02. Combined tool. Stepanov Yu.S., Afanasyev B.I. and others. Application No. 96101389/02, application. 01/23/96, publ. 12/27/97. Bull. No. 36 is a prototype.

Claims (2)

1. The method of combined finishing of the surfaces of revolution, in which the workpiece and the combined tool with a grinding wheel and a shell with working elements are informed of rotational movements and a feed movement along the surface to be machined, characterized in that the combined tool is taken with axial displacement in the direction of longitudinal feed the working layer of the grinding wheel and coaxially mounted on the mandrel of the shell having deforming balls as working elements, while the fastening elements of the combined tool are made in the form of oblique washers in the amount of four pieces, two from each end of the tool to provide an axially offset cutting layer by setting the circle and the shell at an angle to a plane perpendicular to the longitudinal axis, with the possibility of smooth adjustment of the oscillation amplitude by changing the angle of inclination circle and shell. 2. The method according to claim 1, characterized in that the shell assembly for treating metal surfaces with balls comprises left and right covers, peripherally connected by an elastic shell in which nests for balls are made, each socket consisting of a tube with rolled ends, which freely moves the ball, while between the covers there is a set of spacer washers, the total height of which is not less than the height of the elastic shell.

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