Whether the selection of cutting parameters (AP, F, V) is reasonable, plays an important role in giving full play to the potential of the machine tool and the cutting performance of the tool, achieving high quality, high output, low cost, and safe operation. 2.3.3 introduces the general principles of cutting parameter selection. The selection principle of turning parameters is discussed. When roughing, the first thing to consider is to choose a maximum reverse feed, and then choose a larger feed f, and finally determine an appropriate cutting speed v. Increasing the reverse feed ap can reduce the number of tools, and increasing the feed f is conducive to chip breaking. Therefore, according to the above principles, the selection of roughing parameters is conducive to improving production efficiency, reducing tool consumption, and reducing processing costs.
Precision turning requires high machining accuracy and surface roughness, and the machining allowance is small and uniform. Therefore, when selecting the cutting parameters of the fine turning, we should pay attention to how to ensure the quality of the machining and increase the productivity as much as possible on this basis. Therefore, during finishing, you should choose a small (but not too small) back feed AP and feed F, choose a tool material with high cutting performance and reasonable geometric parameters, and increase the cutting speed V as much as possible.
1. Determination of the amount of knife eaten on the back
When the rigidity of the process system and the power of the machine tool allow, choose a larger reverse feed as much as possible to reduce the feed. When parts require high precision, the finishing allowance should be considered. The finishing allowance is generally smaller than that of ordinary turning, generally 0.1-0.5.
2. Article 2. FEED F (the feed speed vf of some CNC machine tools)
The selection of the feed amount F should be compatible with the return amount and the spindle speed. On the premise of ensuring the quality of workpiece processing, a higher feed rate (below 2000/min) can be selected. When cutting or turning deep holes or fine turning, a lower feed rate should be selected. The maximum feed rate can be set when the tool is idling, especially when the tool is "zeroed" for a long distance.
Generally, f=0.3-0.8/r during rough machining, f=0.1-0.3/r during finishing, and f=0.05-0.2/r during cutting.
three. Determination of spindle speed
(1) Bare board spindle speed
The spindle speed should be determined according to the diameter of the machined part on the part, and the allowable cutting speed according to the condition of the part, the tool material and the machining performance.
In addition to calculation and table selection, the cutting speed can also be determined based on actual experience. It should be noted that the low-speed output torque of the CNC lathe with AC frequency conversion speed regulation is small, and the cutting speed cannot be too low.
After determining the cutting speed, the spindle speed n (r/min) is calculated according to the formula n=1000 vc/pi d. Table 5-9 is the reference value of the cutting speed of the carbide cylindrical turning tool.