RU2260507C1 - Method of diamond abrasive treatment of holes - Google Patents

Abstract

FIELD: mechanical engineering; finishing of inner surfaces of revolution.

SUBSTANCE: blank and diamond abrasive wheel are set in rotary motion; feed is moved along surface being treated and cross feed is performed automatically due to elasticity of wheel. Wheel consists of fabric porous envelope secured on elastic porous base and diamond abrasive cutting layer made from two-sided emery cloth secured on envelope. Lubricant-and-coolant medium is fed through pores of wheel. Use is made of mandrel having central axial hole connected with radial holes; it is provided with spacer bush defining height of wheel. Said bush has radial holes coinciding with radial holes of mandrel. End faces of wheel are provided with washers.

EFFECT: increased productivity; improved quality of treatment; extended functional capabilities due to treatment of out-of-round holes.

5 cl, 11 dwg, 1 ex

Description

The invention relates to mechanical engineering technology, in particular to the finishing treatment of both round and non-round inner surfaces.

A known method and device for polishing surfaces, comprising a housing with a spindle bearing an abrasive wheel, and it is equipped with a mandrel with guides perpendicular to the axis of the spindle for moving the housing, made spring-loaded relative to the mandrel and equipped with a spring-loaded shaft mounted parallel to the guide with the possibility of constant contact with the spindle, with this mandrel is equipped with stroke limiters of the housing [1].

The disadvantage of this method and device is low productivity and quality due to insufficient wheel speed, narrow technological capabilities, namely for processing rotating parts, and the inability to process non-circular holes, while the complexity of the design makes the polishing process more expensive. In addition, the design of the tool and the processing method do not allow the supply of cutting lubricants (COTS) directly into the contact zone of the abrasive with the workpiece, which entails an increase in the heat stress of the process and the appearance of microcracks leading to marriage.

A known method and device for polishing surfaces, which includes a mandrel bearing an abrasive wheel, and the mandrel is equipped with a sleeve, which is the inner ring of a roller radial needle bearing, in which the axis of the outer and inner surfaces are made at an angle α and intersect in the center of symmetry with oblique washers, which ends are made at an angle α to each other, by an abrasive wheel, which is made on a flexible (rubber, rubber, volcanic, etc.) base and is mounted on the outer bearing ring at an angle m α to a plane perpendicular to the axis of rotation, while the angle α is determined by the formula

α <arcsin (V _to / D _to ), deg,

where In _to and D _to - respectively the height and outer diameter of the abrasive wheel, mm [2].

The device that implements the method is also equipped with a circular ring truncated at an angle α to the plane perpendicular to the axis of rotation, mounted on the end of the circle coaxially with the mandrel axis, and a two-arm lever pivotally mounted in the arm on the mandrel, with one shoulder in contact with the inner surface of the ring, the other shoulder equipped with a screw screwed into the mandrel and a damping spring. In addition, the mandrel is installed at a distance of N from the work surface and rotates with a frequency of N _o , determined respectively by the formulas:

H = 0.5 [(D _to ² -B _to ² ) ^1/2 ] -B _to tgα, mm,

N _o ≥N _d [2πD _k / L _max ], min ^-1 ,

where N _d is the rotational speed of the part, min ^-1 ;

L _max - maximum arc of contact between a circle and a part, mm.

The disadvantage of this method and device is the design complexity, which increases the polishing process and reduces reliability, as well as the difficulty of adjusting the angle of inclination of the circle (requiring replacement of the sleeve, oblique washers and braking mechanism), necessary when optimizing the processing process in a production environment when changing the processed material , chemical-thermal operations, cutting tools, specifications, cutting conditions. Lack of versatility prevents the processing of non-circular holes. In addition, the design of the tool and the processing method do not allow the supply of cutting lubricants (COTS) directly into the contact zone of the abrasive with the workpiece, which entails an increase in the heat stress of the process and the appearance of microcracks leading to marriage.

The objective of the invention is to increase productivity and quality of processing, simplifying and cheapening the design of the tool, expanding technological capabilities that allow processing non-circular holes, and the ability to apply lubricant-cooling technological means (COTS) directly to the contact zone of the abrasive with the workpiece, in order to reduce the heat stress of the process and increase cutting modes.

The problem is solved using the proposed method of diamond-abrasive processing, in which the workpiece and the diamond-abrasive wheel mounted on the mandrel, inform the rotational movement and the feed movement along the machined surface, and the transverse feed is carried out automatically due to the elasticity of the circle, which consists of a porous fabric a shell fixed on an elastic porous base, with a double-sided diamond abrasive skin used as a diamond-abrasive cutting layer, fixed casing, and the mandrel has an axial, central hole connected to the radial holes for supplying lubricating-cooling technological means (SOTS) through the pores of the circle, and is equipped with a spacer sleeve determining the height of the circle and having radial holes matching the radial holes of the mandrel, washers located at the ends of the circle.

In this case, the diamond-abrasive skin is taken with different grain sizes on each side and in the form of separate petals, which are fixed to the shell with the formation of an intermittent cutting layer, with each petal attached to the shell from only one end face, parallel to the axis.

In addition, the outer diameter of the circle is taken larger than the diameter of the machined hole and the introduction of the circle into the billet hole is carried out using a split conical ring consisting of two ring sectors.

The method allows working in two modes: in the rough diamond-abrasive machining mode with the petals facing the coarse-grained side to the surface being machined when the circle rotates in one direction, and in the finishing mode when the circle is reversed and the circle rotates in the opposite direction, in this case, the petals are turned over due to friction forces with a fine-grained side to the surface to be treated.

In this case, the loose part of the petal, in order to better pass the SOTS and turn the petals when switching from one mode to another, is cut into several parts in the transverse direction.

Figure 1 shows the proposed device, a General view and a partial longitudinal section; figure 2 is a view along A in figure 1, the circle is configured for roughing; figure 3 is a view along A in figure 1, the circle is configured for finishing; figure 4 is a processing diagram of a circular hole of the proposed device, a longitudinal section; figure 5 is a view along B in figure 4, a partial cross section; 6 is a diagram of the processing of an ellipse hole; 7 is a diagram of the processing of a tetrahedral hole; on Fig is a diagram of the processing of a hexagonal hole; Fig.9 is a diagram of the introduction of a circle into the hole of the workpiece; figure 10 - detachable conical ring for introducing a circle into the hole of the workpiece; figure 11 is a view along In figure 10.

According to the proposed method of diamond-abrasive machining of the holes to the workpiece and the diamond-abrasive wheel mounted on the mandrel, rotational movements and the feed movement along the machined surface are reported, while the transverse feed is carried out automatically due to the elasticity of the circle.

A device that implements the proposed method is used for finishing diamond abrasive processing of round and non-circular holes. It contains a mandrel 1, on which a diamond-abrasive wheel 2 is mounted. Mandrel 1 has an axial, central hole 3 connected to radial holes 4, which serve to supply a lubricating-cooling technological means (COTS) through the pores of the wheel directly into the cutting zone.

Circle 2 is equipped with a spacer sleeve 5 that determines its height and has radial holes 6 matching the radial holes 4 of mandrel 1. To maintain the shape of circle 2 in the form of a straight cylinder, it is equipped with washers 7 located at the ends of the circle.

The peripheral surface of the circle 2 is made in the form of a porous fabric shell 8, which is located on an elastic porous base 9 (for example, a rubber sponge, foam rubber, etc.). The porous base 9 was originally taken with a larger diameter than the diameter of the sheath 8, in order to ensure elasticity during assembly.

As a diamond-abrasive cutting layer, a double-sided diamond-abrasive skin is used, which is taken with different grain sizes on each side and fixed to the shell 8 in the form of separate petals 10 with the formation of an intermittent cutting layer, i.e. on the peripheral cutting surface of the circle there are depressions 11 not filled with abrasive and allowing the free exit of COTS to the surface of the circle.

Each petal 10 is fixed (for example, glued) to the shell 8 from only one end 12, parallel to the axis of the circle.

In contrast to traditional abrasive processing, according to the proposed method, the outer diameter of the circle 2 is taken larger than the diameter of the workpiece bore 13 to create elasticity and provide a radial transverse feed S _pop , while the introduction of circle 2 into the workpiece bore 13 is carried out using a split guide conical ring 14 consisting of two annular sectors 15 (see Fig.9-11).

Before processing, the ring 14 with the inlet part 16 is inserted into the hole of the workpiece, and after the introduction of the circle into the hole is removed by opening the lock 17 due to the hinge 18, movably connecting the ring sector 15.

Work on the proposed method is carried out in two modes:

- in the mode of rough diamond abrasive machining with petals facing the coarse-grained side to the surface being machined when the circle rotates in one direction;

- in the finishing mode with reverse and rotation of the circle in the opposite direction, in this case, the petals are turned over due to the friction forces with the fine-grained side to the surface to be treated.

In order to better pass the COTS and flip the petals during the transition from one mode to another, the loose part of the petal 10 is cut into several parts 10 ¹ in the transverse direction.

The assembly of the circle and work on the proposed method is as follows.

The washer 7 is mounted on the mandrel 1 and the sleeve 5 is put on so that the radial holes 6 and 4 are aligned. Then a porous elastic base 9 is pressed onto the sleeve, and the contacting surfaces of the washer, bushings and bases 9 are pre-lubricated with glue. A second washer 7 is placed, on the end of which also glue is applied, and the circle is clamped with a nut.

On a pre-radially compressed elastic base 9, a sheath 8 is assembled with diamond abrasive blades assembled with glue on its inner surface. After the glue has dried and the adhesive joints have set, the circle is ready for use. When diamond abrasive blades are worn, the sheath 8 assembly is forcibly replaced with a new one. A diamond skin is highly resistant; one set of a shell with diamond petals mounted on a ⌀50 mm circle and a height of 30 mm can process 30 ... 50 thousand holes [3].

The input of the circle into the hole to be machined is made when the workpiece and the tool are stationary with the help of a conical guide ring 14, which is inserted into the hole of the workpiece by the inlet part 16, and is removed after the introduction of the circle.

Next, the rotation of the workpiece V _s , the rotation of the circle V _to and the longitudinal feed S _ol for processing the hole along the entire length are included. Radial cutting S _pop diamond-abrasive grains is provided due to the elasticity of the circle.

Processing holes according to the proposed method consists of two transitions. The first transition - roughing is carried out when the circle rotates in one direction, when the petals face the coarse-grained side to the surface to be treated. Switching to the second transition - finishing is carried out by changing the direction of rotation of the circle, while the petals are turned, like the pages of a book, by turning the fine-grained side to the surface to be treated.

The method of diamond-abrasive hole processing allows you to use one of the most effective methods of supplying SOTS and feeding it under pressure through the central hole of the mandrel and the pores of the wheel directly into the contact zone of the abrasive with the workpiece, reducing the heat stress of the process, which allows to increase the cutting conditions. The easy penetration of COTS into the contact zone is also facilitated by: a porous fabric shell, a discontinuous peripheral diamond-abrasive surface of the circle and transverse cuts of the petals, dividing them into parts 10 ¹ .

When processing round holes, the axis of rotation of the circle is combined with the axis of the machined hole of the workpiece (see figure 4-5). However, having the property of elasticity and the ability to change its external configuration, the axis of the circle can be offset relative to the axis of the workpiece and it becomes possible to process non-circular holes (see Fig.6-8).

Example. A through hole of a flange of 7 50 H7 ^(+0.025) mm and a length of 40 mm was ^{processed on an internal grinding} machine mod. 3K228V. The workpiece material is steel 45, hardened, hardness HRC 45. The method of fastening the workpiece is in the cartridge. The technological system machine - tool - tool - workpiece is quite rigid. The roughness parameter of the treated surface is Ra 0.32 μm. The circle is made of ⌀ 64 mm and a height of 30 mm on a foam basis, the petals of the skin are grit on the one hand 14A12, on the other - 14A4. The allowance on the side is 0.05 mm, the circle rotation frequency is 13000 min ^-1 (V _c = 34 m / s), the workpiece rotation frequency is 191 min ^-1 (V _c = 0.5 m / s), the longitudinal feed is S _ol = 0.05 m / s. Coolant - 5% aqueous solution of emulsol in water. The petals of the skins were impregnated with a composition containing 40% paraffin, 55% PVC grease and 5% graphite in order to better flip the petals when switching from one mode to another and lower the temperature.

To obtain the necessary accuracy and roughness, it took half the time than with traditional processing.

The method improves productivity and quality of processing, simplifies and cheapens the design of the tool, extends technological capabilities and allows you to process non-circular holes.

Sources of information

1. A.S. USSR 622647, MKI V 24 V 5/02. Device for polishing surfaces. B.M. Nikiforov and R.P. Chauzov. Application No. 2150282 / 25-08, decl. 07/01/75, publ. 09/05/78. Bull. No. 33 is a prototype.

2. RF patent No. 2202461, MKI 7 V 24 V 29/00, 45/00. Device for polishing surfaces. Stepanov Yu.S., Afanasyev B.I., Borodin V.V., Fomin D.S. Application 2001123492/02, declared 08.21.2001, publ. 04/20/2003, bull. No. 11.

3. Reference technologist-machine builder. In 2 vols. T.1 / Ed. A.G. Kosilova and R.K. Meshcheryakova. - 4th ed., Revised. and add. - M.: Mechanical Engineering, 1986. P.443.

Claims (5)

1. The method of diamond-abrasive machining of holes, in which the workpiece and the diamond-abrasive wheel mounted on the mandrel, inform the rotational movement and the feed movement along the machined surface, characterized in that the transverse feed automatically due to the elasticity of the circle, which consists of a porous fabric shell mounted on an elastic porous base, while a diamond-abrasive cutting layer using a double-sided diamond abrasive skin, mounted on the shell, and carried out the lubricant-cooling technological means (SOTS) are fed through the pores of the circle, for which they use a mandrel having an axial central hole connected to the radial holes and equipped with a spacer sleeve that determines the height of the circle and having radial holes matching the radial holes of the mandrel and washers located at the ends of the circle. 2. The method according to claim 1, characterized in that the diamond-abrasive skin is used with different grain sizes on each side and in the form of separate petals that are fixed to the shell with the formation of an intermittent cutting layer, each petal being fixed to the shell with only one end face parallel to the axis. 3. The method according to claim 1, characterized in that the circle is used with an outer diameter larger than the diameter of the hole to be machined, while introducing the circle into the billet hole using a split conical ring consisting of two annular sectors. 4. The method according to claim 2, characterized in that the treatment is carried out in two modes: in the rough diamond-abrasive treatment mode - with the petals facing the coarse-grained side to the surface being machined, while the circle rotates in one direction and in the finishing mode - with the petals turned upside down fine-grained side to the work surface, due to friction forces during reverse and rotation of the circle in the opposite direction. 5. The method according to claim 4, characterized in that the non-fixed part of the petal is cut into several parts in the transverse direction for better passage of the COTS and the flipping of the petals when switching from one mode to another.

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