The processing technology of CNC lathe is similar to that of ordinary lathe. However, as CNC is a kind of clamping, continuous automatic processing completes all turning process, so attention should be paid to the following aspects.
- Reasonable selection of cutting parameters
For efficient metal cutting, machining materials, cutting tools and cutting conditions are the three main factors. These factors determine the processing time, tool life and machining quality. An economical and effective machining method must be a reasonable choice of cutting conditions.
Three factors of cutting conditions: cutting speed, feed and cutting depth directly lead to tool damage. With the increase of cutting speed, the tool tip temperature increases, resulting in mechanical, chemical and thermal wear. Increasing the cutting speed will reduce the tool life by half.
The relationship between feed condition and tool wear is very small. However, when feeding, the cutting temperature increases and the wear occurs. It has less effect on the tool than on the cutting speed. Although the influence of cutting depth on cutting speed and feed rate is not as great as that of cutting speed and feed rate, the hardened layer produced by cutting material will also affect the tool life when cutting at small cutting depth.
The user should select the cutting speed according to the material, hardness, cutting state, material type, feed rate and cutting depth. The following table:
According to these factors, select the most suitable processing conditions. The ideal state is to wear regularly and stably to reach the service life.
But in practice, the choice of tool life is related to tool wear, size change, surface quality, cutting noise, processing heat and so on. When determining the processing conditions, it is necessary to study according to the actual situation. For refractory materials such as stainless steel and heat resistant alloy, coolant or hard blade can be used.
- Select a tool
1) The cutter with high strength and good durability shall be selected to meet the requirements of thick tooth turning, large back cutting and large feed.
2) Precision turning, select high precision, good durability tool, to ensure the machining accuracy requirements.
3) In order to reduce the tool change time and facilitate tool alignment, the machine clamping tool and the machine clamping tool should be used as far as possible.
CNC machining
- Reasonable selection of fixture
1) Try to use general fixture to clamp workpiece and avoid using special fixture;
2) Parts positioning datum coincide to reduce positioning error.
- Determine the processing route
Machining path is the exponential control of the tool path and direction relative to the part in the machining process.
1) Ensure machining accuracy and surface roughness;
2) The processing route should be shortened as much as possible to reduce the tool idle travel time.
- Relationship between machining route and machining allowance
At present, it is not widely used in CNC lathe. Generally, the blank should be put on the surplus allowance, especially the allowance with forging and casting hard skin should be processed on the common lathe. If you must use CNC lathe processing, then you must pay attention to the flexible arrangement of the program.
- Key points of fixture installation
At present, the connection between hydraulic chuck and hydraulic clamping cylinder is realized by pull rod. The critical point chuck of the hydraulic chuck is as follows: first, remove the lifting hand of the nut on the hydraulic cylinder, pull out the tube, and extract from the rear end of the shaft, and then put the chuck fixing screw on the raised hand, chuck can be removed.
The polished edge on the tool refers to a small part of the blade, which is worn along the side deviation direction behind the blade and parallel to the tool tip. The blade is mainly used for the second cutting after cutting edge cutting, which is equivalent to removing burrs and scars in the process of finishing. Its purpose is to improve the surface roughness of the workpiece, which is mainly used for the finishing of cutting tools.
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