Huo, Jie Jin gang.

(Sanmenxia Vocational and Technical College, Sanmenxia, Henan 472000)

Abstract: Process analysis and parts processing program in NC machine tool processing are the key factors affecting processing quality and efficiency. minute

The optimization measures of technology and programming in NC machining are analyzed. Combined with the processing of actual parts, corresponding measures are taken to effectively improve the numerical control.

The utilization rate of machine tools improves the processing quality of parts.

Keywords: NC machining; Technology; Numerical control programming; Optimize

China picture number: TG659

1 preface

How to tie a knot when machining mechanical parts with CNC machine tools?

According to the characteristics of machine tools and parts, fully consider the processing technology, and

Clever application of programming methods and skills to optimize the process and editing of NC machining

Process, is of great significance to ensure and improve the machining quality of CNC machine tools.

Meaning. In this paper, how to optimize the NC machining process and programming, improve

The quality of NC machining is discussed.

2 Optimization of processing technology

(1) Reasonable Design of Cut-in and Cut-out Paths in Profile Milling

When milling the outline of a part, in order to avoid cutting in and out, a tool is generated.

With notch, in order to ensure the surface quality of the part contour, the tool is designed to cut.

When leaving the path, avoid cutting in and out along the normal direction of the outline of the part. interrupt

When cutting the workpiece, gradually cut into the workpiece along the extension line or tangent direction of the cutting starting point.

Parts, to ensure the smooth transition of parts curve. Similarly, when cutting a workpiece

When cutting, you should also avoid lifting the knife directly at the cutting end and follow the cutting end.

The point extension line or tangent direction gradually moves away from the workpiece.

When milling the inner groove, the radius of the fillet of the selected tool conforms to the figure of the inner groove.

Paper requirements, in order to ensure the surface roughness of parts, make the feed route.

Short, you can cut off the surplus in the middle part by wire cutting, and finally by ring cutting.

Cutting a knife can not only shorten the total feed route, but also get a better watch.

Surface roughness.

(2) Avoid the influence of the reverse clearance of the mechanical feed system on the machining accuracy.

affect

The long service life of CNC machine tools is still due to its own transmission system structure.

There may be a reverse gap error and the reverse gap error will

The positioning accuracy of coordinate axis is affected, and the positioning accuracy in hole group is increased.

Man-hour not only affects the center distance between holes, but also affects the positioning accuracy.

The degree is not high, resulting in uneven machining allowance and geometric shape error.

If the tool constantly changes the feed direction during machining, it will

The reverse clearance of coordinate axis is brought into machining, which leads to the increase of positioning error.

At this time, when arranging the feed route, the reverse rotation of the mechanical feed system can be avoided.

Influence of radial clearance on machining accuracy.

As shown in figure 1, move the tool to the center of the hole quickly after confirmation.

If the feed path is designed according to figure 1(a) when machining the route.

The line, namely 1-2-3-4, is due to the positioning of 4 holes and 1, 2, 3 holes.

On the contrary, the reverse clearance in Y direction will increase the positioning error, which will affect

4 Position accuracy of holes and other holes. If the feed is designed according to figure 1(b)

Route, after processing 3 holes, move up a distance to point P, but

Then turn back and locate at four holes, so that the direction is the same.

The introduction of reverse clearance can be avoid, and that positioning accuracy of the four hole can be improved.

Figure 1 Comparison of Machining Routes of Hole Series

Figure 1 tool path comparison of array holes

Also as shown in fig. 2, finish machining the outline of the stepped shaft. If numbers are used,

(a) Change the machining route with reverse clearance to the design shown in Figure (b)

Working route, and then the tool moves continuously in the radial direction during finishing.

Increase the trend, the axial movement makes the size move to the left continuously, so that

The influence of the reverse clearance of the mechanical feed system on the machining accuracy is avoided,

And the dimensional accuracy is improved.

Fig. 2 Processing route of finishing step shaft

Fig. 2 Finishing route of stepped shaft

(3) Correctly handle the dimensional tolerance of part drawings.

When compiling the program, we should correctly handle the dimensioning on the part drawing.

Many dimensions of parts are marked with tolerances, but the position of each tolerance zone is not.

May be consistent, and CNC programs are generally programmed according to the outline of the parts, that is, according to zero.

The basic dimension programming of parts ignores the influence of tolerance zone position. such as

If the dimensions marked are asymmetrical, even if the precision of the CNC machine tool is higher,

Machined parts may not meet the dimensional tolerance requirements.

If the parts shown in Figure 3 are machined, the parts will use the same milling cutter and the same

When the tool radius compensation value is programmed, the contour of the part is different.

Due to different tolerance zones, it is difficult to ensure that all dimensions are in proportion at the same time.

Within the tolerance of inches. At this time, its tolerance zone should be adjusted, adjusted.

The method is as follows: under the premise of keeping the limit size of the part unchanged, program.

When calculating, change the profile size and move the tolerance zone to the symmetrical size.

As shown in the brackets in Figure 3, the tolerance zone is adjusted according to.

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