1. Selection principle of cutting parameters
Reasonable cutting parameters refer to the cutting parameters that make full use of the cutting performance of cutting tools and machine tools, and obtain high productivity and low processing cost on the premise of ensuring the processing quality. Due to different processing properties, the requirements for cutting processing are different. Therefore, when selecting cutting parameters, the emphasis of consideration is also different.
During rough machining, try to ensure a high metal removal rate and necessary tool durability. When selecting cutting parameters, we should first select the maximum back feed, then select the maximum feed according to the constraints of machine tool power and rigidity, and finally determine the appropriate cutting speed according to the requirements of tool durability.
When finishing, first determine the back cutting amount according to the rough machining allowance, then select the appropriate feed rate according to the roughness requirements of the machined surface, and finally select a higher cutting speed as far as possible on the premise of ensuring the durability of the prop.
2. Selection method of cutting parameters
(1) Selection of back knife size
During rough machining, in addition to leaving finish machining allowance, all allowance shall be cut off as far as possible in one cutting. When the machining allowance is too large, the rigidity of the process system is low, the power of the machine tool is insufficient, and the tool strength is insufficient, the tool can be moved several times. When cutting castings and forgings with hard skin on the stool surface, try to make the back cutting amount greater than the thickness of the hard skin layer to protect the knife tip.
(2) Determination of feed speed (feed rate)
Feed speed is an important parameter in the cutting parameters of CNC machine tools. It is mainly selected according to the machining accuracy and surface roughness requirements of parts and the material properties of tools and workpieces. The maximum feed speed is limited by the machine tool stiffness and the performance of the feed system.
During rough machining, since there is no high requirement for the surface quality of the workpiece, the feed speed is mainly selected according to the strength and rigidity of the machine tool feed mechanism, the strength and rigidity of the tool bar, the tool material, the size of the tool bar and workpiece, and the selected back feed.
(3) Determination of cutting speed
The cutting speed can be selected according to the selected back feed rate, feed rate and tool durability. In the actual processing process, it can be selected according to the production experience and the method of looking up the table.