SU1763152A1 - Method of polishing screw surface of blades - Google Patents

Abstract

Usage: in metalworking. SUMMARY OF THE INVENTION Grinding of a blade is carried out by longitudinal lines with a cylindrical working surface. The end of the circle is installed in a plane passing through the generator of the screw surface of the blade, and contact is made with it on convex sections of the sections by planes perpendicular to the generator. During processing, the rotating grinding wheel reports reciprocating movement along the generatrix of the screw surface and coordinated rotation around this generatrix, as well as movement along the axis of the screw surface, consistent with rotation of the screw around this axis 2 Il.

Description

The invention relates to the processing of materials with abrasive tools and is used in mechanical engineering in the manufacture of blade products, such as propellers, turbines.

There is a known method of grinding blades, in which the screw surface is processed by longitudinal lines with a grinding wheel shaped along a radius, which is moved in a plane passing through the axis of the product, along the generatrix of the screw surface of the blade being machined, and the part is moved in the direction of the circle. When moving to the next line, the blades are reported to turn, and to the abrasive circle - movement along the axis of rotation consistent with it.

The disadvantage of this method is the low processing performance due to the poor contact shape of the wheel with the blade being machined, since the wheel is profiled along the radius and its profile differs significantly from the blade section profile. Negatively affects the performance and the fact that for each

the screw surface needs to repurpose the circle to a different radius

The aim of the invention is to improve the grinding performance of the helical surfaces of the blades, in particular in the form of a direct helicoid.

This is achieved because the grinding of the screw surface of the blade is carried out by a cylindrical circle, one of the ends of which is arranged to coincide with the plane of the forming screw surface, and the opposite end above the convex part of the screw surface, while moving the circle along the screw surface. his position is kept unchanged

FIG. Figure 1 shows a kinematic grinding scheme for the blade; Figure 2 illustrates the location of the grinding wheel relative to the generator and the axis of the helical surface.

The screw surface in the form of a straight helicoid blade 1, for example the propeller 2, is machined with grinding wheel

VI

 WITH

cl

hO

gome 3 having a cylindrical work surface. The grinding wheel is positioned relative to the blade in a position, based on the conditions of its end face coinciding with the plane of arrangement of the generatrix 4 of the screw surface perpendicular to its axis 5, and of the position of the opposite end above the convex part of the helical surface in sections of six planes perpendicular to 4 When moving the circle 3 along the generatrix 4, its specified position remains unchanged, so that the generatrix 7 of its working surface is constantly tangent to the cross-section 6 of the helical surface.

The blade is treated with longitudinal lines. For this, the grinding wheel 3 is informed by the rotation of the HF around its axis 8 with the frequency n and the reciprocating movement of P2 along the generatrix 4 of the screw surface with the speed SM. The rowing screw 2 is reported to periodically or continuously rotate Pz around axis 5, and to the grinding wheel a translational movement Pz aligned with this rotation along axis 5.

If the propeller is given a periodic rotation Vs between the lines, then the angle t / of this rotation is

-Ј.т

where b is the width of the line;

R is the propeller radius.

In this case, the grinding wheel is reported to move along the axis of the screw surface to a distance consistent with this rotation.

C - Y

With 2n

The maximum angle of the periodic rotation of the propeller corresponds to the maximum width of the b line, at which the height D of the interline crests does not exceed the allowable value. If the propeller is reported to continuously turn B3. then, in one double stroke of the grinding wheel, it should not be rotated by an angle exceeding its value determined by the formula (1).

Simultaneously with the translational movement of P4, the grinding wheel is informed by the rotation Bs around the generatrix 4 screw surface, which changes the angle P between the axes 5 and 7 of the screw surface and the wheel according to

P-tg-agad L -, (3)

where / is the current value of the angle between axes

circle and screw surface;

mm

(2)

and

ten

15

20

25

thirty

35

40

bff

45

50

55

Н - pitch of the screw surface;

S - movement of a circle from the axis of the helical surface.

This dependence is determined from the following considerations. The angle (see Fig.2) of the inclination of the tangent 7 to the convex section of the flat section of the blade passing through the point O of the contact of the circle with the helical surface (its forming 4) is equal to the elevation angle of the helix passing through this point, i.e. .

  arctg s {4)

where S is the distance from point A to axis 5. Therefore, the angle α / 3 between axes 5 and 8 is expressed by dependence (3).

At the specified location of the circle 3 relative to generator 4, regardless of the pitch H of the screw surface and the distance S from the section 6 under consideration to its axis 5, the contact of the straight forming surface of the grinding wheel with the convex part of this section takes place. This form of contact of the wheel with the blade allows, with the same quality of processing, to increase the width of the line and, consequently, the performance in the form of a straight helix according to the proposed method can be processed by one Grinding wheel with a cylindrical working surface. Thereby eliminating the need to profile the working surface of the grinding wheel for a certain radius, which simplifies the implementation of the method.

The height A of the interstitial ridges with the line width b (Fig. 2) is determined by the dependence

d-AzZL {)

Section 6 of the helical surface helical helicoid in the XOZ coordinate system is described by the equation

Zl.JL.ercta.x, (6)

where H is the pitch of the helical surface;

S is the distance from the axis 5 of the helical surface to the section under consideration.

For right-handed helical surfaces, H is positive, and for left-handedness it is negative. The equation forming the cylindrical surface of the grinding wheel in the same coordinates is:

22 X-1dr X -. (7)

Therefore, the height of the interline combs

-Z7Farc S- |)

H

(eight)

x cusarctg -.

and stitch width

and

b "X / cos X / cosarctg- - -, (9)

where X is determined from expression (8) for a given value of L.

From expressions (6) and (7), it follows that section 6 and the forming cylindrical working surface of the grinding wheel in the area of its contact with the blade are close enough to each other, which allows for high processing performance.

Claims (1)

The invention of the method of grinding the screw surfaces of the blades, in which the abrasive Yu 15 the circle is reported to rotate and move along the generatrix of the screw surface, while turning to the next line of the blade the turn is reported, and the abrasive circle is coordinated with it moving along the axis of rotation, characterized in that, in order to increase the grinding performance of the helical surfaces in the form of a straight helix, the end of the abrasive wheel is placed on the condition that it coincides with the plane of the forming screw surface and on the condition of the opposite end above the convex part of the screw surface. at the same time, when moving the circle along the generatrix, its specified position remains unchanged. , -3