SU1763091A1 - Method of machining with kinematic chip slotting - Google Patents

Abstract

Usage: in metal cutting and kinematic crushing chips on machine tools with numerical control. SUMMARY OF THE INVENTION: the tool is reported with additional movements that accomplish with decreasing the working feed at the starting point of the circular arc to zero at the tool’s touch point of the specified part contour and its subsequent increase to the working feed at the point distant from the specified contour finishing processing, and the radius g of the circumference of the additional movement is assigned from the ratio g (1 + t) / 2t, where t is the value of the allowance for finishing, 2 Il.

Description

The invention relates to machining and can be used in machining fittings on lathes and, in particular, on CNC machines.

There is a known method of kinematic crushing of chips on CNC lathes, in which the tool, in addition to moving in the feed direction, is informed by additional reciprocating movements in the direction constituting an angle of 20-50 ° with the direction of the instantaneous feed vector (A.P. No. 795718 , class B 23 V 1/00).

There is also known a method of kinematic crushing of chips on CNC machines, in which additional movements are made at an angle of 20-40 ° to the instantaneous feed vector, then parallel to the instantaneous feed vector in the opposite direction and further at an angle

p 180 ° - and to the instantaneous feed vector (AS No. 1214327, cl. B 23 V 1/00).

The disadvantage of these methods of crushing chips is the reduction in processing performance due to the presence of idle tool movements; In addition, undercutting of the tool after making its idle movements on the workpiece, the appearance of undercuts is possible.

The purpose of the invention is to improve the performance of the turning process with kinematic crushing of chips while improving the quality of turning.

The goal is achieved by the fact that in the method of kinematic crushing of chips, including tool movements in the feed direction and additional movements for chip breaking, the latter are performed on a semi-finish passage into the part body along an arc of a circle of radius

cl

with

XJ ABOUT

o you

g

1 + t2 2t

where t is the value of the allowance for finishing, until the tool touches the nominal contour with a decrease in the working feed from the starting point of the arc to zero at the point of contact of the tool with the nominal contour and a subsequent increase to the working feed at the point of the arc spaced from the nominal contour at a distance t, a finishing pass is made along the contour of the part without additional movements,

FIG. 1 shows the position of the tool relative to the workpiece on the semi-finish pass; in fig. 2 shows the position of the tool on the final (finishing) aisle, during which the contour of the part with nominal dimensions is formed. In both figures, the dashed-dotted line indicates the contour with nominal dimensions, the dotted line indicates the contour after the half-finish pass; solid thick line - contour areas after turning.

The claimed method of kinematic crushing of chips is carried out in two passes of the tool: semi-finishing, in which the allowance is removed with the value A and the allowance is left with the value of t relative to the nominal contour, and finishing, in which the remaining allowance is removed by the value of t. In the semi-finish pass, tool 1 is smoothly supplied at the working feed Sp to the workpiece 11, which has an allowance relative to the nominal size of the contour of (A +1), taking into account this allowance, the plunging is performed tangentially to the contour and removed the allowance of D (Fig. 1) ). At the working feed, Sp is processed to point 1, which is at a distance of I from the end of the part. In this area of processing, the chips are continuous. From point 1, the magnitude of the submission S decreases, at the same time moving the tool along an arc of a circle of radius

g

2t

to point 2 on the nominal contour; at the specified point 2, the feed value is reset to zero. As the workpiece continues to rotate at a predetermined number of revolutions n, chip breakage will occur at point 2. From point 2, the tool is moved further along an arc of a circle of radius r with a gradual increase in the feed rate to point 3, which is at a distance t from the nominal contour. At point 3, the feed amount is increased to its working value Sp. On this feed

producing the next section of the contour of length I with the removal of the allowance value A. The described process is repeated cyclically until it makes a half-finish pass along the entire length of the contour of the workpiece. The length I, which determines the dimensions of the crushing sections, is chosen on the basis of the diameter of the workpiece and the properties of the material being processed. For the most common sizes of steel billets, the value of I is in the order of 10-15 mm. After completing the semi-finish pass, the tool is in rapid feed.

return to the starting position.

Next, a finishing pass is performed, for which the tool at the working feed Sp again is smoothly brought to the end of the part, tamping into the contour is performed and the tool is moved along the entire contour length, removing the remaining allowance of t (Fig. 2). In region 1-2 (FIG. 1), the thickness of the chips being removed is reduced to zero, and

as a result, chip breakage occurs at point 2. In section 2-3, the thickness of the remaining allowance gradually increases, therefore, the tool plunges smoothly and gradually increases the force on the tool to remove the allowance in the next part contour of part I. The breakage of the chip occurs periodically at each part of the contour of part I (for example, in section 2-4 in Fig. 2). Finishing is carried out by continuously moving the tool at the working feed Sp over the entire length of the contour of the part, after which the machining is completed and the tool is returned to its original position at an accelerated feed.

The radius r, with which the auxiliary movement of the tool along the arc of a circle is performed, is calculated

the outcome of the following considerations. The maximum value of allowance t for finishing does not exceed 1 mm, so the distance between the boundary points of the arc of a circle 1 and 3 can be taken equal to 2 mm.

(at ti 1 mm, the auxiliary tool movement will be performed along an arc of a semicircle with a radius of 1 mm). Let O be the center of a circle of radius r (zone A in Fig. 1). Drop perpendicular from points 3

0-2 to the intersection at point B. Nebrehring by changing the radius of curvature of the contour in section 1-3, we can assume that the distance from point B to point 2 is t; then the segment 0В g - t. Considering that

the length of the half chord is 1 mm from the right-angled triangle 0-3-B; we have r2

91 + T

1 + (r - tf; whence r -jj-.

A billet with a diameter of 40 mm and a length of 75 mm from material 12X18H10T was machined with an ATPR machine until a part of a cylindrical shape with a diameter of DH 36.8 mm was obtained. A seam allowance of 1 mm was removed at the semi-finish pass, and t 0.6 mm for the finishing pass. The radius of the auxiliary displacements was assumed to be

g

 1 + 0.62

 1.13 mm.

2 -0.6

The number of revolutions of the spindle n 1000 r / min, the value of the working feed Sp 0.1 mm / rev, (or 100 mm / min); the length of the contour sections where chip breakage should occur was taken equal to I 15 mm. Thus, on the semi-finish passage, four auxiliary tool displacements along an arc of a circle with a radius of 1.13 mm were performed with an initial deceleration of feed to zero at the tool’s contact point of the nominal contour and its subsequent increase to Sp value 0.1 mm / rev,

The finishing pass of the tool was made by continuous movement of the tool at the same feed; at the same time, chip breakage 0.6 mm thick occurred in five contour sections.

Compared with the prototype, which was chosen as the method of kinematic crushing chips, described in and.with. No. 1214327, the use of the claimed method allows to increase the processing efficiency by eliminating idle movements of the tool during the cutting process. However, the machining quality is improved, since the finishing pass is carried out by continuously moving the tool at a constant feed in the direction tangential to the contour; The beginning of the removal of each new section of chips is carried out with a gradual increase in the thickness of the allowance, so the cutting forces increase smoothly and not stepwise, as a result of which no cuts are formed on the machined contour.

Claims (1)

Invention Formula A machining process with kinematic crushing of chips, in which parts and tools report relative rotational movement of cutting and feeding, as well as additional movements for chip breaking along a circular arc, characterized in that, in order to increase processing performance, additional movements are performed with decreasing working feed at the starting point of the circular arc to zero at the point of contact of the tool of the specified part contour and its subsequent increase to the working feed at the point, spaced from the predetermined contour at a distance of the value of the allowance for finishing, and the radius of the circumference of the additional displacement is assigned 1 + t2 from the relation, where t is the value allowance for finishing, Phage. one FIG. 2 F “, b