SU654397A1 - Method of joing grinding of intersecting surfaces - Google Patents

Description

one

The invention relates to the field of belt polishing of the junction points of intersecting profile surfaces, for example near the joints of gas turbine engine blades.

A known method for joint grinding of intersecting surfaces, for example, near the joints of the blades, in which the abrasive belt is moved in the direction from one intersecting surface to the other by means of a contact copier 1 fed into the incision.

The known method of processing when grinding parts both by the method of running in and copying with a narrow abrasive tape, when the treatment area during the cross feed of the belt (or part) is displaced in the direction perpendicular to the plane of rotation of the belt, and the feed angle for piercing during processing remains constant , does not provide, as will be shown below, the necessary durability of the tape and the quality of the surface at the required level of productivity due to a change in the wide range of the ratio of the lengths of the processed cross xc surfaces in different longitudinal sectional x blade.

The aim of the invention is to improve the quality of processing and durability of the tape by ensuring equal pressures on the treated surfaces.

This goal is achieved by changing the feed angle during the operation and choosing its outcome from the dependency:

tg V,

 COS a + 1c 11.1

where Yt is the current value of the feed angle

contact copier for plunging, counted from the surface;

"R is the current value of the angle of intersection of the surfaces; in and ki is the current value of the lengths of the surfaces to be processed in the plane of rotation of the abrasive belt.

FIG. Figure 1 shows schematically the surface treatment with a narrow abrasive belt using the copy method; in fig. 2-6 the same wide abrasive belt running; in fig. 7-10 shows the topography of the junction areas of some types of blades of modern gas turbine engines; in fig. 11, a, b — zoo treatments in two different longitudinal sections of the blade; see 12 is a diagram of the action of forces in a treatment zone located in an arbitrary t-TOM longitudinal section of the blade. When processing the areas of blades by the method using a narrow abrasive tape (see Fig. 1), tape 1 reports rotation with Vi speed and reciprocating movements of 5 liters along the chord of the pen, and the equidistant copy of the blade section copier 2 or blade 3 is fed to the incision along the arrow is 5p and the direction of the nodalis assignment during the machining process remains constant. Tape 1 can rotate in the same plane, and the copier 2 and paddle 3 jointly perform rocking movements in a plane perpendicular to the plane of rotation of the tape. In both cases, the cutting zone will in the process of reciprocating movement, for example, from the input edge to the output edge and back. When processing by the rolling method (see Fig. 2), the tape 1, the envelope of the contact copier 2, reports the rotation speed UL, and the blade 3 is rolled at SOQ along the straight line forming the copier, which is fed to the plunge along the arrow 5вр, and the cutting direction is the run-in process is also kept constant. At the same time, in different A-A, B-B, B-B, and so-called NN sections. (see Fig. 3) The copier is equidistantly conjugated to the longitudinal section of the blade. With this method of scanning, as with the method of copying, the treatment zone also moves along the blade chord, and in different longitudinal sections A-A, B-B, B-B, the ratio of the lengths processed / 1 shelf and / 2 feathers does not remain constant. and is determined by the geometry of the part. From the drawings (see Figs. 8, 9, 10) it can be seen that the ratio of the lengths of the machined intersecting surfaces of the turbine and compressor blades varies in a wide range. Thus, when machining the back of a turbine blade (see FIG. 8), shelf 1 and the oblique section 3 are simultaneously grinded — part of the pen profile 2 adjacent to the shelf, the plane of which makes an angle r with the perpendicular to the longitudinal axis of the blade. When the treatment zone moves from the output edge to the input edge, the shelf / c, liz, / 13, etc. sections are sequentially processed, and the corresponding sections of the pen profile, the lengths of which, on the contrary, decrease, are also processed. A section of the shelf with a minimum length of / imm and is processed in the section. the section of the pen profile is kr long, and the Wimin ratio is very large, since / imm is almost zero. In the D-D section, a shelf section with a maximum length / imax is processed. And a pen profile section with a length / 2b, here, as follows from the drawing, /. The 2D // iniax 1U of some types of blades, the dimensionless parameter K, equal to the ratio of the processed profile and shelf lengths, can change during processing from some finite value to zero or infinity. For example, when processing a blade (see Fig. 9), when the treatment area is to the left of the input edge and to the right of the output edge, only shelf 1 is grinded, and I, therefore, is zero. When processing, for example, a rotary compressor blade (see Fig. 10), at some points in time, on the contrary, only nero 2 is skipped and v equals infinity. When the feed angle piercing Y is constant and the angle of intersection of the surfaces of the normal values of the normal components of the total cutting force (see Fig. 12) in different longitudinal sections along each of the surfaces to be machined will remain constant. As a result, a change in the grinding area of the surfaces to be machined (due to a change in the lengths of the surfaces in the direction of cutting) is accompanied by a change in pressure on the areas to be treated - in areas with a larger area, pressure will be less than in areas with a smaller area. And since the intensity of metal removal, as is known, is proportional to normal pressures, the removal rate of the allowance will be much higher in areas of small length than in areas with large length. The removal rate of the allowance unambiguously determines the qualitative aspects of the grinding process, the frequency of the ground surface, the heat intensity of the process, the distribution and depth of the residual stresses, the depth and intensity of the burns, the wear rate of the abrasive tape, etc. Thus, when grinding the cool areas of the blades with a constant nodal angle for piercing, in nerves, prizk cc on different surfaces is unevenly removed, and secondly, the process of intensive removal of metal in areas with a small area of cutting with supported by significant contact temperatures in the treatment area and temperature gradients in the surface layer of the part, which does not guarantee against the occurrence of burns and cracks, thirdly, high temperatures, contributing to the emergence and development of chemical, diffusion, electrocontact and other processes in the treatment area, reduce durability abrasive belts and surface quality. Since the conditions of the grinding process continuously change during one double casting blade with a copier or one double stroke of an abrasive mite, the rozani modes have to be determined based on unfavorable treatment conditions, which reduces the processing efficiency. According to the invention, the abrasive tape

1 bends the contact coir 2 and, rotating in the plane of the drawing with the speed of the UL, reciprocates in a plane perpendicular to the plane of the drawing.

Detail 3 (or copier 2) served on the copier

2 (or on part 3) in the direction of the SBP, the feed rate, at an angle of 7; to the machined surface / s (see figs. 11 and 12), the current value of which during the transverse movement of the belt or the displacement of the treatment area as a result of the blade roll is changed so that the pressure on both the machined surfaces B during the process of changing the ratio of the lengths of the machined surfaces would be the same.

If the lengths of the machined surfaces intersecting at an angle a were the same, then it would be necessary to designate the infeed angle y to be equal to a / 2, i.e., to cut down along the bisector of the intersection angle of surfaces. If the length Aa of the surface from which the angle is counted in some current longitudinal section is longer than the length / 2a of the interfaced surface (Fig. H), then for the pressures on both surfaces to be equal, it is necessary that the angle y be greater a / 2, i.e. the direction of feed must be deflected towards the surface with a shorter length. On the contrary, if in the longitudinal section I / b / 2b (see Fig. 11.6), then it is necessary to fulfill the condition YG a / 2.

Let the lengths of intersecting at an angle a / the surfaces of the workpiece 3 in some r-long longitudinal section of it be equal to / and ki. When part 3 is fed into plunging along Sup, the grinding force P acts, which is an angle y with a surface of length / i ;. Then the normal forces acting on the surface will be equal

P ,, PI sin Tb - PI sin (“r - t,).

and the corresponding surface pressures:

PII

Pi-slnii Lg-1

III

  PlSln (, i) hi -i (21

From the condition of equality of pressures on both surfaces, we have

1 (Pr1From here

/ liSina ,;

tg

U /, / COS at + / о. Changing the direction of the feed of the incision in the process of displacing the processing zone transverse to the plane of rotation of the belt can be carried out by mechanisms known and intended for similar tasks.

The proposed grinding method allows to improve the quality of processing and the durability of the molds with the same processing modes as the prototype or to increase the productivity of processing by using higher modes. The processing efficiency is also increased by reducing the cost of abrasive belts.

The values of the above positive effects depend on the geometrical parameters of the workpieces, mainly on the change in the ratio of the lengths of the intersecting surfaces in different longitudinal (parallel to the rotational lengths) sections of the blades.

Claims (1)

Invention Formula A method of co-grinding intersecting surfaces, for example, near the joints of the blades, which is moving in the direction from one intersecting surface to the abrasive Leita is pressed in the direction of the iodine angle and pierced with a contact copier, characterized in that, with an increase in the quality of processing and durability of the tape by ensuring equal pressures on the surfaces to be treated, the iodach angle is changed during operation and is based on: Sin a; tgT (COS Y + 45 Where 7d is the current zoom of the feed angle of the contact copier and the incision measured from the surface; a, - is the current value of the angle and intersection of the surfaces; ki and / 2t is the current length of the surfaces to be processed in the plane of rotation of the abrasive belt. Sources of information, irintye in heed during examination 1. USSR author's certificate N ° 360202, cl. At 24V 21/06. 1969. 2 7oS srig.2 ig.8 .. A t f i 7 / rg:; Wfe 7 II 2srig .З rig.10 , U Kr