RU2422251C2 - Method of milling complex surfaces - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: method relates to milling surface profiles consisting of two or more shaped or straight sections and comprises continuous feed of mill relative to workpiece along one trajectory, common for different workpiece sections. To add to efficiency and quality, mill feed trajectory is defined by equation proposed herewith.

EFFECT: higher efficiency and precision.

2 cl, 7 dwg

Description

The invention relates to the field of machining - milling with an end mill of surfaces of a complex flat contour, including two or more sections of different shapes, including a shaped and straight-line intersecting with it.

Closest to the claimed invention is a method in which the relative movement of the cutter and the workpiece is carried out by equidistant to each individual section of the circuit (Sosonkin V.L., Martinov G.M. Numerical control systems. M. Logos. 2005. 296 p .; p. 263; 264-266; 124).

In the known method, the milling cutter moves relative to the workpiece along separate equidistant paths that are different for different parts of the contour. In this case, intermediate, transitional trajectories are required that take into account the plunging and overrun during the processing of each section and docking different trajectories.

A sharp change in the direction of feed motion occurs, which is unfavorable for dynamic loads on the technological system; the processing of the entire circuit is interrupted, additional errors arise in the mutual arrangement of the contour sections. The length of the general path increases due to the presence of additional transitional sections on it (see also Fig. 7). When developing control programs for CNC systems, separate software of additional transition paths is also required, which ensure the joining of adjacent equidistant loops (Sosonkin V.L., Martinov G.M. Numerical control systems. M. Logos. 2005. 296 p .: p. .124).

The problem to which the claimed invention is directed is to exclude various trajectories of the workpiece during processing of various sections of the contour, as well as to exclude additional, transitional sections of the trajectory of the workpiece during processing by milling various sections of the contour of the part, including the shaped and straight; smoother, without a sharp change in direction, the movement of the workpiece.

This technical result is achieved by the fact that the movement of the workpiece relative to the cutter when processing various sections of a complex contour, including shaped and rectilinear, according to the invention is carried out along one path common to different sections of the contour and determined by one mathematical equation:

where A, B are the coefficients of the equation (real numbers), A = 0.1, B = -1.5 × 10 ^-4 ;

n and m are exponents taken at least 2, m = 4, n = 2;

x, y - coordinates of the points of the contour of the workpiece in a plane perpendicular to the axis of the cutter, in which the workpiece is moved; while the movement is carried out continuously along the path described above when processing two or more sections of the contour, including shaped and straight, in the absence of intermediate paths.

The method is presented in figures 1-7, which show various paths of movement of the cutter relative to the workpiece.

The method is implemented as follows. The workpiece is moved along the path (1), while the contour L of the machined surface is formed as the envelope of the circle family of the cutter with a radius r equal to half the diameter of the cutter, in the form of an acfeqs line with a number of singular points (return and intersection) (Fig. 1).

The real contour of the part is limited by the contour lines ab, sg and the straight section bg. Two shaped and straight sections of the contour L intersect at points b and g.

The gq, qe, eg, and be, cf, fb sections serve as transitional between the machining of shaped and straight sections and provide cutting and overrun cutters. These sections are formed not due to additional trajectories of movement of the workpiece, as in the known method, but due to the displacement of the forming point M on the circumference of the cutter with its relative movement along the mentioned path. Therefore, additional, intermediate trajectories with this method is not required. The movement during the processing of all sections of the circuit is carried out along one common path. The parameters of the equation A, B, n, m and the diameter of the cutter are assigned taking into account the shape and size of a given contour.

Choosing the appropriate cutter radius r and parameters in the trajectory equation, they ensure not only the intersection of different sections of the contour L (as in FIG. 1), but, if required, also their smooth conjugation along the curved line L (as in FIG. 2 and FIG. 3).

It is also possible to provide a milling of the contour L with three contoured sections — ab, bg and gs — intersecting at an acute angle at the points of bug (Fig. 4). The real contour of the part in this case is limited by the lines ab, bg and gs.

Shaped sections of the contour (for example, lines ab and sg, Fig. 1) can be defined by the equation, the coordinates of the points, one or more arcs of circles of different radii.

The rectilinear section, in particular, perpendicular to the y axis, is defined by the length of the segment bg.

Methods of mathematical modeling calculate the actual surface obtained by machining a mill with a given diameter when it moves along the path described above. The calculations showed that the method provides a deviation from linearity in the bg section with a length of 3-20 mm (Fig. 1) within 0.2-2 microns.

The method is used and tested when processing surfaces of complex contours on a CNC machine mod. 24K40FZ (modernized, using end mills).

Figure 5 shows the contour L obtained with one common trajectory and consisting of two shaped convex sections sg and ga intersecting at point g. Inside the sga loop is the “body” of the part. The line U (shown by dots) is a trajectory. The parameters (A, B, etc.) of the trajectory are given. The diameter of the cutter is 20 mm (r = 10). The dimensions on the x, y axes are given in mm.

Figure 6 shows a similar contour L, but with other parameters of the trajectory and the diameter of the cutter (parameters A, B and others are given in Fig.6). The diameter of the cutter is 25 mm (r = 12.5). The “body” of the part here is also inside the sga loop. The sections sg and ga have a shape concave inside the “body” of the part.

Fig. 7, for comparison, shows the path of the cutter when processing the contour L (consisting of sections sg and ga) by a known method. The center of the mill circumference with radius r moves along two different paths - equidistant U ₁ and U _{2 of the} circuit L. In addition, additional sections of the cutter path for overrun, cutting and connecting points are needed: sections 1-2 (overrun), 2-3 (retraction, so as not to cut off the point g of the contour), 3-4 (connection), 4-5 (approach), 5-6 (plunge).

Claims (2)

1. The method of milling the surface of the workpiece with a complex contour consisting of two or more sections of different shapes, including the relative movement of the end mill and the workpiece, characterized in that when processing shaped and intersecting straight sections of the contour, the end mill moves continuously along one common path which is determined by the equation:

where x, y are the coordinates in the plane perpendicular to the axis of the cutter in which the cutter is moved;
A = 0.1, B = -1.5 · 10 ^-4 , m = 4, n = 2. 2. The method according to claim 1, characterized in that the parameters common for different sections of the path and the diameter of the cutter are set such that they provide processing of the contoured section of the contour, outlined in one or two arcs of circles.

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