SU1315262A1 - Lap for machining holes - Google Patents

Abstract

The invention relates to the field of metalworking and can be used for diamond and electrochemical grinding of cylindrical holes on the finishing machines. The purpose of the inventive shade is to increase the capacity of the operation of grinding the holes by increasing the intensity of correcting the errors of the geometric shape of the holes by keeping the correct cylindrical shape with the lap of the unclamping and significant increase in the stiffness of the ground-mandrel system. Two abrasive elements are installed symmetrically with respect to the cut on the outer surface of the split shirt, the edges of the two other abrasive elements are arranged at an angle of 110-115 to the middle of the cut, with the width of each of the last abrasive elements being 1.3-1.9 width of each of the abrasive elements. - with cops installed at the cut. Gil,.; ®

Description

The invention relates to metal processing, in particular to the design of a tool for grinding high-precision holes, and can be used for diamond and electrochemical grinding of cylindrical holes on the finishing machines.

The aim of the invention is to increase the productivity of grinding of cylindrical holes by increasing the intensity of correcting the errors of the geometric shape of the holes by keeping the correct cylindrical shape with grinding with the opening and significant increase in the stiffness of the grinding-mandrel system.

Figure 1 shows the proposed priter, the cross-section.

The lap consists of a split shirt 1 and abrasive elements 2-5, which can be attached to the shirt 1 by soldering, gluing or in another way.

Consider the lateral deformation of the lap during unclamping. In the process of lapping, as the allowance is removed from the surface of the hole, the outer diameter of the tool increases with a conical mandrel 6. Shirt 1 of the lapping undergoes uneven deformation in the transverse direction.

The areas AB and FD of the inner surface of the lap move away from the surface of the mandrel, forming gaps between them. Tight fit of shirt 1 and mandrel. 6 is observed at sites near points A and F and at site BD. Fixing the abrasive elements in these zones avoids the negative effect on the processing accuracy of the uneven deformation of the shirt, so that the abrasive elements are fixed on the shirt sections that receive the same movements during the deformation, as a result, the shape of the working surface of the tool does not change as well as to avoid the occurrence of radial beating of lapping over the beams during unclamping, which negatively affects the accuracy of processing (this is explained by the fact that the abrasive elements, when unclamping, receive the same the magnitude of the displacements, as a result of this, the center of the circle described by the bars does not shift relative to the center of the mandrel), and increase the stiffness of the lap in the transverse direction (0

five

The presence of an air gap between the lap body and the conical mandrel does not affect the stiffness of the lap). Owing to the increased stiffness of the lap, the pressure fluctuation in the treatment zone does not change the correct cylindrical shape of the lap over the bars during the final adjustment.

Experimental studies have shown that during the unclamping of the jacket 1, the priter is constantly in contact with the mandrel 6 along the arc of the BCD. The central angle cf, which is supported by the arc of a constant contact, is 140 for all possible implements of lapings. The corresponding ° С angle, defining the location of the contact zone, relative to the middle of the shirt section, is about: 180 –tf / 2 110.

0 At this angle, as in any size, you must assign a tolerance. Tolerance should be set in the direction of increasing the angle. The tolerance value can be accepted 5. Then the angle about is in the range 110-115. If the abrasive elements A and 5 are located at an angle ck, then a part of the elements is on that part of the shirt 1, between which and the mandrel there is a gap. The stiffness of the lapping system — the mandrel is reduced and the productivity is reduced accordingly. Improving the angle oi more than 115 is impractical because it leads to the need to reduce the width of the abrasive elements

4 and 5. I

A decrease in the total width of the abrasive elements leads to a decrease in

Q performance. The most appropriate is the range of values of the angle about 1 10-1 15 °.

In order to ensure uniform wear of the tool, it is necessary to establish ratios between the width of abrasive elements 2 and 3 and the width m of elements 4 and 5. Taking into account that when lapping, the tool self-adjusts on the surface to be treated, the lapping is in balance under the action of two forces P and two forces R. Make the equation of the projections of forces on the vertical axis:

2P.COS 5 - 2R.cos О, (1) 5 where / and y are the angles that define the angular coordinates of the points of application of forces.

The force acting on the surface of the abrasive element is 0

pressure on the area. We substitute these expressions into formula (1) and reduce it by 2:

 b-c-cos - 0, (2)

where P is the pressure on the surface

abrasive elements 2 and 3) is the pressure acting on the surfaces of abrasive elements 4 and 5; b - the length of the abrasive elements J

c is the width of elements 2 and 3 $ m is the width of elements 4 and 5. Uniform wear of abrasive elements is observed in the case of equality of the pressure values on the surfaces of elements 2, 3 and 4, 5. Then equation (2) takes the form

cos y

from m- :.

cos.

This expression sets the ratio of the width of the abrasive elements from the condition of uniform wear in-. strument.

Angle / 3 is determined from

(3)

/ 3 | 5p-f arcsln-,

where - half of the central angle corresponding to half the width of the cut;

DH - outer diameter of priter. The angle y is determined from the expression

13152624

V Yt

 T - 5;

five

-

five

0

where (f 140 is the central angle resting on the arc of the constant contact of the sleeve of the lap with the mandrel.

On the basis of the sizes of the lapping shirts by expression (3), the boundaries of the ratio of the width of the abrasive elements are equal to t / s 1.3-1.9. An increase or decrease in this ratio leads to more intensive wear of elements 2 and 3 or 4 and 5, respectively.

Claims (1)

Invention Formula A grinding hole for machining holes, containing a split jacket mounted on a conical mandrel, on the outer surface of which, abrasive elements are installed symmetrically relative to the cut, two of which are located directly at the edges of the cut, characterized in that, in order to increase productivity, the edges of the two other abrasive elements are located under an angle of 110-115 to the middle of the cut, and the width of each of the last abrasive elements is 1.3-1.9 times the width of each of the abrasive elements installed at the cut. Have Editor I.Nikolaychuk Compiled by A.Shutov Tehred L.Oliinzh Order 2255/15 Circulation 715 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., d. A / 5 Production and printing company, Uzhgorod, st. Project, 4 Proofreader G. Reshetnik