Three principles of CNC machining
CNC machining usually refers to computer digital control precision machining, CNC machining lathes, CNC machining milling machines, CNC machining boring and milling machines, etc. CNC is also called computer gong, CNCCH or CNC machine tool. It is a new type of processing technology, and its main work is to compile processing programs, that is, to convert the original manual work into computer programming. Of course, manual processing experience is required
1. The principle of one-time positioning, the process is concentrated to the greatest extent.
Generally, on CNC machine tools, most of which are processed on the machining center, the process flow can be centralized to the maximum extent, that is, most or all of the process processes that can be processed by this CNC machine tool should be completed as much as possible in one clamping. CNC machining tends to centralize the process flow, which can reduce the number of machine tools and the number of workpiece clamping, reduce unnecessary positioning errors, and have high productivity. For the processing of the hole system with high coaxiality, after one installation, the tool should be continuously changed according to the sequence to carry out all the processing of the coaxial hole system, and then the holes of other parts should be processed to eliminate the harm of repeated positioning errors. , to improve the coaxiality of the hole system.
2. The principle of rough first and then fine.
When carrying out CNC machining, when dividing the process according to the machining accuracy, stiffness and deformation of the parts, the sub-process should be carried out separately according to the roughing and finishing, that is, after all the roughing is completed, the semi-finishing and finishing are carried out. For a machined surface layer, it should be carried out according to the roughing-semi-finishing-finishing process. During rough machining, it is necessary to give full play to the characteristics of the machine tool and the cutting performance of the tool under the conditions allowed by the machining quality, tool durability and the rigidity of the machine tool-fixture-workpiece process system software, and to use as much cutting times as possible to obtain finishing. The processing condition of the remaining parts of the previous parts is as uniform as possible. The key to finishing is to ensure the precision and surface quality of the part, so the last contour of the part during finishing should be continuously finished by the last knife. In order to ensure the processing quality, in general, the finishing allowance should be 0.2-0.6 mm, and the interval between roughing and finishing is preferably a period of time, so that the deformation of the parts after roughing can be fully repaired, and then finishing is carried out. , to improve the machining precision of parts.
3. The principle of first near and then far, first face and then hole.
According to the distance of the processing part relative to the tool setting point, in general, the part close to the tool setting point is processed first, and the part far from the tool setting point is processed later, so as to shorten the tool moving distance and reduce the idle travel time. For turning, it is also beneficial to maintain the rigidity of the blank or semi-finished product and improve its cutting conditions. For the machining of parts with both plane milling and boring, it can be carried out in the order of first milling the plane and then boring. Because the cutting force is large when milling the plane, the parts are prone to deformation. First, the surface is milled and then the hole is boring, so that it can recover for a period of time. After the deformation is restored, the boring is beneficial to ensure the machining accuracy of the hole. Secondly, if boring first When the plane is milled after the hole, the hole will produce burrs and burrs, which will affect the assembly of the hole.
