RU2239542C1 - Built-up abrasive tool - Google Patents

Abstract

FIELD: machine engineering, possibly dimensionless finishing of part surfaces by means of petal type discs.

SUBSTANCE: built-up abrasive tool is in the form at least of three petal type abrasive discs. The last are mounted by inclination angle relative to plane normal to rotation axis in common shaft with axial gap. Mean disc is mounted in shaft in rolling bearing assembly with possibility of free rotation. Petals of mean disc are made of double-side grinding cloth in the form of ellipse and they are arranged across rotation axis. Small axis of ellipse is equal to diameter of discs; large axis is determined depending upon inclination angle of discs.

EFFECT: enlarged manufacturing possibilities due to working by means of two ends of discs, enhanced efficiency and quality of finishing due to increased axial rigidity of tool and due to crossed disc motion paths.

3 cl, 8 dwg

Description

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

Known prefabricated abrasive tool made in the form of a pair of abrasive wheels fixed at an angle to each other on a common shaft with an axial clearance [1].

The disadvantages of the known 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.

Known prefabricated abrasive tool made in the form of a pair of abrasive wheels fixed at an angle to each other on a common shaft with axial clearance, and 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 tool are:

- minimum axial rigidity of the tool, not allowing to achieve high performance;

- work on only one side of the peripheral abrasive surface of the tool greatly increases the complexity of processing;

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

- difficulties in achieving a wide range of quality of the treated surfaces.

All this reduces processing productivity, quality and leads to increased tool consumption.

The objective of the invention is to expand the technological capabilities of the tool by providing the possibility of processing with two ends of the petals of the tool, which is installed at an angle to the axis of rotation, increasing productivity by increasing the axial rigidity of the tool due to the use of abrasive petals in the form of an ellipse, as well as improving the quality of processing due to the cross longitudinal-transverse the intersection of the trajectories of the polishing wheels.

The problem is solved using a precast abrasive tool, which is made in the amount of at least three abrasive flap wheels, fixed at an angle to a plane perpendicular to the axis of rotation, on a common shaft with axial clearance, and the middle circle is mounted on the shaft by means of a bearing with the possibility of free rotation and consists of petals made of double-sided grinding skin and located transverse to the axis of rotation, while the petals are elliptical, the small axis of which is equal to the diameter of the tool, and the major axis is determined by the formula

b = D / cosα,

where b is the major axis of the ellipse, mm;

D is the outer diameter of the tool, mm;

α is the angle of inclination of the circles to a plane perpendicular to the axis of rotation, which is determined by the formula

α ≤ arctan (A _O / D),

where A _O is the amplitude of the oscillating cutting zone of inclined circles, adopted

A _O ≤ B,

here B is the height of the middle circle, mm.

Moreover, the remaining circles are fixed rigidly on the shaft and consist of petals located along the axis, and are installed radially.

In addition, the graininess of the middle circle is higher by number than the graininess of the remaining circles.

The invention is illustrated by drawings. Figure 1 shows the design of a precast abrasive tool, a partial axial section; figure 2 is a General view of the tool, rotated half a turn relative to the position shown in figure 1; figure 3 is a section aa in figure 1; figure 4 is a view along A ¹ in figure 1; figure 5 is an ellipsoidal petal of a double-sided grinding skin; in Fig.6 - element B in Fig.1, the position of the petals of the middle circle in the zone of contact with the treated surface; in Fig.7 - element B in Fig.2, the position of the petals of the middle circle in the zone of contact with the treated surface; on Fig - scan tool track on the work surface when it is rotated one revolution and the direction of movement of the abrasive grains of various circles.

The proposed prefabricated abrasive tool allows you to finish at the same time in the longitudinal and transverse directions both with round and flat polishing.

In the middle circle, the working cutting elements of the tool are ellipsoid petals 1 from a double-sided grinding skin located transversely, and the remaining circles are composed of petals of an abrasive skin located radially in the longitudinal direction.

The assembled abrasive tool is made in an amount of at least three abrasive flap wheels 2, 3 and 4, fixed at an acute angle α to a plane perpendicular to the axis of rotation on a common shaft 5 with an axial clearance. The middle circle 3 is mounted on the shaft 5 by means of a bearing assembly 6 with the possibility of free rotation and consists of petals 1 made of double-sided grinding skin and located across the axis of rotation. The bearing assembly 6 includes a sleeve 7 with oblique ends and an angular arrangement of the axes of the inner and outer surfaces, a flange 8, which is mounted on a rolling bearing using spring thrust concentric rings (taken, for example, according to GOST 13940-80 and GOST 13941-80). On the flange 8 using the nut 9, the petals 1 of the movable circle 3 are fixed.

Petals 1 have the shape of an ellipse, the small axis of which is equal to the diameter of the tool, and the large axis depends on the angle of rotation and is determined by the formula

b = D / cosα,

where b is the major axis of the ellipse, mm;

D is the outer diameter of the tool, mm;

α is the angle of inclination of the circles to a plane perpendicular to the axis of rotation, which is determined by the formula

α ≤ arctg (A _o / D),

where And _about - the amplitude of the oscillating cutting zone of inclined circles, adopted

A _about ≤ B,

here B is the height of the middle circle 3, mm.

The remaining circles are 2, 4, etc. fixed on the shaft rigidly with the help of oblique washers 10, 11, nuts 12 and consist of petals located along the axis and are installed radially (see figure 4).

The granularity of the middle circle 3 is greater by number than the extreme ones, i.e. the middle circle with a larger grain is intended for pre-polishing. Extreme circles 2, 4, etc. fine-grained are intended for finishing processing.

The tool is installed on a circular, inside, or surface grinding machine, and the workpiece in the appropriate device. The rotation V is reported to the shaft 5, the tool is tightened by means of the transverse feed S _pop and the longitudinal feed to the workpiece S _cp , as well as during _circular and _{internal grinding} work, the workpiece is rotated. For a full revolution of the tool shaft, circles 2 and 4 smoothly change their angular position to the left and right of the normal by an angle α with respect to the work surface.

The circle 3, movably mounted with the help of the bearing unit 6 on the shaft 5, is rolled around the machined surface and, thanks to its inclination in the contact zone with the workpiece, makes oscillating oscillatory movements along the longitudinal axis of rotation.

Moving along the surface of the workpiece machined by circle 2, the movable circle 3 in the contact zone cuts off microroughnesses in the direction perpendicular to the risk-scratches cut by circle 2 (see Fig. 8); during the reverse stroke, moving along the machined circle 4. Due to the inclination of the middle circle and the interference fit carried out by S _pop , the main force on the surface being machined is carried out by the parts of the petals located on the periphery and having the greatest deflection (see Figs. 6 and 7). The direction of the deflection of the petals varies depending on the angular position of the circle. If the contact zone of the middle circle with the workpiece is located to the right of the normal (see Fig. 6), then the deflection direction is to the right, while the petals work with the left abrasive end, if the contact zone is to the left of the normal, then the deflection direction is to the left, and the petals work right abrasive end face (see Fig.7).

When polishing is carried out for a long time as the petals wear, under the action of the transverse feed S _{pop, the} weakened transverse interference is restored and the design provides an improved quality of processing in terms of reducing the roughness of the processed surface of the workpiece.

In connection with what has been said during this longitudinal-transverse polishing, the proposed tool manages to remove large allowances (for example, up to 0.3 mm) when using coarse-grained abrasive skins (grain size 16-80) and high cutting speeds (15-35 m / s).

This process is actually a form of grinding and is effective for preparing surfaces for fine polishing and before metal coating.

Polishing with a prefabricated tool is intended to reduce the surface roughness parameter (to Ra = 0.1 ... 0.8 μm) without eliminating the deviations in the shape of the parts.

The greatest effect of the use of oscillating polishing is achieved during decorative finishing and finishing of shaped surfaces, for example, polishing cylindrical and conical surfaces, processing of molds, dies, etc., polishing curved surfaces of automobile bodies, refrigerators, and others for painting.

Polishing with the proposed tool is carried out mainly according to one cutting pattern, which is based on the use of high cutting speeds (10 ... 40 m / s), approaching the grinding speed. The peripheral speed of a circle during oscillating polishing of parts from: steel, nickel and chromium 20 ... 35 m / s; copper, brass and bronze 16 ... 25 m / s; aluminum, zinc and lead 12 ... 20 m / s.

However, low speeds _{Sp for} moving the workpiece (which is typical for flat polishing) contribute to improving the quality of processing.

The most applicable for the proposed tool are circles 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 the operation of this tool, circles made of water-resistant diamond-abrasive skins are used when processing parts made of steel, cast iron and brass, and an emulsion is used as a cooling liquid; from non-waterproof skins - mineral oils.

The proposed prefabricated tool expands technological capabilities by providing the possibility of processing with two ends of the petals that make up the middle circle, improves productivity and quality of processing by installing circles at an angle to the axis of rotation and free installation of one of the circles, increasing axial rigidity due to the use of abrasive blades in ellipse shape.

Sources of information

1. A.S. 689823 USSR, 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 (3)

1. A prefabricated abrasive tool made in an amount of at least three abrasive flap wheels fixed at an angle to a plane perpendicular to the axis of rotation on a common shaft with axial clearance, characterized in that the middle circle is mounted on the shaft by means of a bearing with the possibility of free rotation and consists of petals made of double-sided grinding skin and located transverse to the axis of rotation, while the petals are elliptical, the small axis of which is equal to the diameter of the tool, and the large axis is determined by mule: b = D / cosα, where b is the major axis of the ellipse, mm; D is the outer diameter of the tool, mm; α is the angle of inclination of the circles to a plane perpendicular to the axis of rotation, determined by the formula α ≤ arctg (A _o / D); A _o - the amplitude of the oscillating cutting zone of inclined circles, taken A _o ≤ B; In - the height of the middle circle, mm 2. The tool according to claim 1, characterized in that the remaining circles are fixed rigidly on the shaft and consist of petals located along the axis and mounted radially. 3. The tool according to claim 1 or 2, characterized in that the graininess of the middle circle is one number greater than the graininess of the remaining circles.

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