Machining skills for common arcs in CNC turning - News - Global IC Trade Starts Here.

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Compared with ordinary lathes, CNC lathes have strong adaptability, high processing precision, high production efficiency, and can complete the processing of complex profiles. With the development of new products, the shape is more and more complex, and the precision requirements are getting higher and higher. It is undoubtedly to give full play to the advantages of CNC lathes. Arc machining reflects the advantages of CNC lathes. However, in the actual processing of large arcs, programming difficulties are often caused due to improper selection of machining processes or lack of auxiliary calculation tools, and abnormal machining errors occur in severe cases. This has attracted my attention. Through long-term trial cutting experiments, it is proved that the following methods are simple in the arc programming, and the processed parts have high precision. Below I will discuss with several common parts as an example.

First, the circular layer cutting method

1) The starting point and end point of the arc are unchanged, only the radius R is changed.

As shown in Fig. 1, machining a convex arc in the part, according to the two points as the arc, the smaller the radius, the greater the curvature. Therefore, when cutting the convex arc, the starting point and the end point can be fixed and the radius R is gradually reduced. Increase to the specified size. However, it should be noted that the radius of the arc should be at least half of the length of the finished circular chord.

figure 1

N10 G01 X40 Z-5 F0.3;
N20 G03 X40 Z-25 R10.2 F0.2;
N30 G00 X53;
N40 Z-5;
N50 G01 X40 F0.3;
N60 G03 X40 Z-25 R12 F0.2;
N70 G00 X53;
N80 Z-5;
N90 G01 X40 F0.3;
N100 G03 X40 Z-25 R16 F0.1 :

2) The starting point and end point of the arc change, and the radius R does not change.

As shown in Fig. 2, a concave arc is machined on the part. In order to reasonably distribute the amount of the knife and ensure the processing quality, the cutting is performed by the equal radius arc, and the programming idea is simple.

figure 2

N10 G01 X54 Z-30 F0 .3;
N20 G02 X60 Z-33 R10 F0 .2;
N30 G00 X54 Z-30;
N40 G01 X48 F0.3 ;
N50 G02 X60 Z-36 R10 F0.2;
N60 G00 X48 Z-30;
N70 G01 X42 F0.3 ;
N80 G02 X60 Z-39 R10 F0.2;
N90 G00 X42 Z-30;
N100 G01 X40 F0.3;
N110 G02 X60 Z-40 R10 F0.1;

3) Arc start point, end point coordinates, radius R change

As shown in Fig. 3, a hemisphere is machined at one end of the part. In this case, the radius R of the path of the path is equal to the difference between the change of the last path radius R and the direction of Z (or X) ∆Z(∆X). .

image 3

N10 G01 X0 Z10 F0.3;
N20 G03 X60 Z-20 R30 F0.2 ;
N30 G00 Z6;
N40 X0;
N50 G03 X60 Z-20 R26 F0.2;
N60 G00 Z2;
N70 X0;
N80 G03 X60 Z-20 R22 F0.2 ,
N90 G00 Z0;
N100 X0;
N110 G03 X60 Z-20 R20 F0.1;

Second, the first cone and the arc method

In this method, the excessive cutting allowance is first cut off by the method of the car cone, and the last arc cutting path is formed by cutting the arc, as shown in FIG. 4 .

Figure 4

N10 G01 X102 Z-30 F0.3;
N20 G90 X100 Z-50 I-5 F0.2;
N30 I-10;
N40 I-15;
N50 I-20;
N60 G01 X60 Z-30 F0.3;
N70 G02 X100 Z-50 R20 F0.1;

When it is a convex arc, the length of the ab segment can be calculated according to the geometric knowledge, and then the car cone, and finally the arc, as shown in Fig. 5.

Figure 5

Db=1.414R+R=0.414R
Ab=1.414*db=0.585R

To retain a part of the finishing allowance, then ab takes 0.5R.

Ab=bc

According to the method in 1, the taper is first processed, and then the arc is refined.

Third, the conclusion

In CNC machining, the machine tool operator is often the compiler of the part cutting program, which requires the programming process to be simple, easy to adjust, and high in machining accuracy. When there is no CAD drawing software, computer or other auxiliary calculation tools at the operation site, programming the cutting arc by the above method can greatly reduce the calculation amount. The idea is simple, the process is decent, the service life of the tool is prolonged, and the precision of the processed parts is high, which brings convenience for the processing of the arc-shaped parts.