RU2284892C1 - Method for diamond-abrasive machining with local contact - Google Patents

Abstract

FIELD: mechanical engineering, in particular, process for grinding and polishing of part surfaces.

SUBSTANCE: method involves imparting rotational motion to blank and rotational motion and motion of feeding along surface under machining process to tool made in the form of petal-type disk with local contact; using petal-type disk mounted by means of skew washers at an acute angle to plane perpendicular to axis of rotation of said disk. Petal-type disk comprises packet of petals, which is squeezed by means of two flanges so as to form radial waves, said petals being provided with wavy internal surface. Petals are made by end gluing of double-sided diamond-abrasive grinding cloth strips so as to define shells and turning inward one of ends of each shell for creating radial waves. Width of strips is selected to be smaller than radius but greater than half the radius of petal-type disk, and length of strips is selected to be equal to length of its circle. As petals wear out, they are put forward in radial direction by means of flanges for recovering external diameter of petal-type disk.

EFFECT: wider operational capabilities and reduced consumption of abrasive material.

10 dwg, 1 ex

Description

The invention relates to mechanical engineering for the mechanical processing of metals and can be used for grinding and polishing the surfaces of parts with their dimensionless final machining with flap wheels.

A known method of diamond-abrasive processing with local contact, implemented by a combined tool made in the form of a pair of circles fixed at an angle to each other on a common shaft with axial clearance [1].

The disadvantages of this method and tool are the limited technological capabilities for decorative finishing and finishing of shaped surfaces, as well as difficulties in achieving a wide range of quality of the machined surfaces, while having minimal axial rigidity and working only on one side of the peripheral abrasive surface, it is impossible to achieve high performance.

A known method of abrasive processing, implemented by a combined tool made in the form of a pair of abrasive wheels, mounted at an angle to each other on a common shaft with axial clearance, the tool is equipped with a tension spring located between adjacent ends of the abrasive wheels, which are installed with the possibility of angular rotation [2 ].

The disadvantages of the known method and tool are:

minimum axial stiffness;

work with only one side of the peripheral abrasive surface;

limited technological capabilities for decorative finishing and finishing of shaped surfaces;

difficulties in achieving a wide range of quality of machined surfaces.

All this reduces the processing performance and leads to increased consumption of expensive abrasive tool material.

The objective of the invention is to expand the technological capabilities of the method due to the localization of the contact, which is oscillating and running due to the installation of the tool at an angle to the axis of rotation, which allows to process the two ends of the petals that make up the tool, by increasing the axial stiffness due to the use of abrasive petals in the form of a circle with radial waves, which allows to increase the cutting conditions, as well as the economical use of abrasive material and the cheaper process and manufacturing tool.

The problem is solved using the proposed method of diamond abrasive machining, including the message of the rotational motion of the workpiece and the rotational motion and the feed motion along the machined surface of the tool in the form of a petal circle with a local contact, using a petal circle installed using oblique washers located at the ends under sharp angle to a plane perpendicular to the axis of its rotation, and consisting of a petal packet clamped with two flanges to form radial waves which are made with a wavy inner surface and obtained by gluing at the end of the strips of a double-sided diamond-abrasive grinding skin with a width of less than a radius, but more than half the radius of the petal circle, and a length equal to its circumference, with the formation of shells and the turning of one of the ends of each shell with the formation of radial waves, while with the wear of the petals they are extended in the radial direction using flanges to restore the outer diameter of the petal circle.

Features of the method is illustrated by drawings.

Figure 1 shows a diagram of the proposed method and a petal circle with a local contact for its implementation, a partial longitudinal section; figure 2 is a view of figure 1; figure 3 is a strip of double-sided grinding skins, a blank for the manufacture of a petal; figure 4 is a shell made of strip (figure 3), a semi-finished petal; figure 5 is a new, unworn petal with a symmetrical arrangement of radial internal waves relative to the plane of the petal; in Fig.6 is a view of B in Fig.5; figure 7 - element In figure 1; on Fig - element In through a half-turn of the tool relative to Fig.7; figure 9 is the most worn petal; figure 10 is a view of B 'in figure 9.

The proposed method of diamond abrasive processing, in which the workpiece and the tool in the form of a petal wheel 1 with a local contact, assembled from petals from a grinding skin and installed at an acute angle to a plane perpendicular to the axis of rotation, rotational movements and feed motion along the surface to be processed are reported.

The petal wheel 1, which implements the method, has a peripheral diamond-abrasive working cutting part with axial displacement due to the installation of the wheel at an angle α to the plane perpendicular to the longitudinal axis on the spindle 2 using oblique washers 3 located at the ends and secured by a nut 4.

The diamond-abrasive wheel 1 is made in the form of a combined petal wheel and consists of petals 5. The petals 5 are made of strips of a double-sided grinding skin (Fig. 3) with a width h less than a radius, but more than half the radius R of the circle, i.e. R> h> R / 2 and a length πD equal to its circumference. Shells are glued from strips (Fig. 4), having previously prepared strips for gluing by overlapping by cutting smaller ends with the removal of grinding material from both ends of the tape in the area under the seam. Then one of the ends of the shell is turned inward with the formation of radial waves. Figures 5 and 6 show a new, unworn petal with a symmetrical arrangement of radial internal waves relative to the plane of the petal. Turning the shells inward is easy to do if you use special flanges 6, which allow you to form a package of petals with the formation of bilateral radial waves 7 and which we use in the proposed tool for attaching a package of petals.

As the petals wear, they are pulled out in the radial direction, restoring the outer diameter D. This design of the petals allows you to constantly restore the outer diameter of the rapidly wearing flap diamond abrasive tools and make full use of expensive diamond abrasive material (see Figs. 9-10).

When restoring the outer diameter D of the petals 5, it must be borne in mind that d5 the inner diameter of the petals is not larger than the outer diameter d6 of the clamping flanges 6, otherwise the petals will not be clamped.

Due to the wavy shape of the inner surface of the petals of the diamond-abrasive wheel, its rigidity is higher than that of traditional petal circles, the main force acting on the surface to be treated can be carried out more and more intensively due to deflections of the peripheral parts of the petals (see Figs. 7-8). Deflections to the left (see Fig. 7) and to the right (see Fig. 8) are provoked by setting a circle at an angle to a plane perpendicular to the axis of rotation.

Thus, the local running contact used in the proposed method, contributes to more intensive processing and lower heat stress of the process.

In connection with the above, in the polishing process, it is possible to remove large allowances (for example, up to 0.3 mm) when using coarse abrasive skins (grain size 16-80) and high cutting speeds (65-70 m / s). This process is actually a form of grinding and is effective for preparing surfaces for fine polishing and before metal coating.

Finishing polishing by the proposed method, implemented by a petal wheel with local contact, is intended to reduce the surface roughness parameter (to Ra = 0.1 ... 0.8 μm). The greatest effect of the use of oscillating polishing is achieved with decorative finishing and finishing of shaped surfaces, for example polishing of cylindrical and conical surfaces, processing of molds, dies, etc., polishing curved surfaces of automobile bodies, refrigerators, etc. for painting.

Polishing by the proposed method is carried out mainly according to one cutting pattern, which is based on the use of high cutting speeds (35 ... 40 m / s), approaching high-speed grinding.

The most applicable for the proposed method are tools made of petals made of electrocorundum and silicon carbide skins on a fabric and paper basis with a grain size of 8-M40, as well as diamond and elbor skins with a grain size of 12-M3 on an elastic bond, while the latter are highly resistant.

For tools made of waterproof diamond-abrasive skins, when processing parts made of steel and cast iron, an emulsion is used as a cooling liquid; from non-waterproof skins - mineral oils.

The proposed technical solution improves the efficiency of using a polishing tool that can restore the outer diameter and allows processing using the entire peripheral working part of the tool while maintaining the advantages of the intermittent grinding process.

Example. On a modernized machine mod. 16K20T1 polished the workpiece in the form of a shaft with a diameter of 20 mm from steel 45 in a normalized state. The upgrade consisted of installing a device with an outer diameter of 250 mm and an individual drive on the transverse caliper.

Petals were made from a waterproof double-sided fabric elbor (elbor sanding powder LO 50/40, OST 2 MT79-2-88) sandpaper with a grain size of 50/40, made according to TU 2-036-0224450-014-89 electrostatically in the form of a grinding reel 100 wide mm and up to 100 linear meters. m., bunch - resin SFZh-3039, the base fabric - chiffon. The tape was cut into strips of 100 × 805 mm in size and glued with an overlap into the shells, having previously cut the smaller ends with the removal of grinding material from both ends of the tape in a section under a 10 mm wide seam. The petal circle is made up of 15 petals.

An individual electric drive rotates the flap wheel at a peripheral speed of 32.5 m / s (2500 min ^-1 ). The linear speed of rotation of the workpiece is 0.05 m / s (50 min ^-1 ). Coolant was supplied to the treatment zone as a 5% emulsion solution. The angle of inclination of the petal circle was α = 1 ° 12 ^I.

The set roughness Ra is 0.32 μm. The method and the tool implementing it allowed to increase the productivity of the process by 2.1 times and reduce the consumption of abrasive by 32%.

The method extends the technological capabilities of processing due to the more rigid construction of the tool and the installation of diamond-abrasive blades at an angle to the axis of rotation, which allows to increase the cutting conditions, and this increases the processing productivity by 2 ... 2.5 times, improves the quality and roughness of the processed surface.

The proposed method allows to restore the outer diameter of the tool and process using the entire peripheral working part of it while maintaining the advantages of the intermittent grinding process. The method is simple to use, and the tool is not complicated in design and reliable in operation, while the consumption of an abrasive tool is reduced by 30 ... 35%.

Information sources

1. A.S. 689823 SSS, MKI B 24 D 5/00. Prefabricated abrasive tool. 1977.

2. A.S. 1692824 USSR, MKI B 24 D 13/00. Prefabricated abrasive tool. A.V. Chemersky and V.N. Cheshev. No. 4700372/08, declared 04/18/89, publ. 11/23/91. Bull. No. 43 is a prototype.

Claims (1)

The method of diamond-abrasive processing, including the message of the rotational motion of the workpiece and the rotational motion and the feed motion along the machined surface of the tool in the form of a petal wheel with a local contact, characterized in that they use a petal wheel mounted with oblique washers located at the ends at an acute angle to the plane perpendicular to the axis of its rotation, and consisting of a packet of petals clamped with two flanges with the formation of radial waves, which are made with a wavy internally surface and obtained by gluing at the end of the strips of a double-sided diamond-abrasive grinding skin with a width of less than a radius, but more than half the radius of the petal wheel, and a length equal to the length of its circumference, with the formation of shells and the unfolding inside one of the ends of each shell with the formation of radial waves, however, as the petals wear, they are advanced in the radial direction using flanges to restore the outer diameter of the petal circle.

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