Precision CNC machining of those things
CNC precision machining refers to the high precision marked on the production and processing drawings, which requires the completion of precision machining equipment.
The ultra-precision processing equipment of mechanical processing manufacturers mainly include: CNC machining center, precision grinding machine and CNC lathe; CNC machining center has high precision, high precision, complex type, small batch parts processing has unique advantages; precision grinding machine belongs to precision processing equipment One is mainly the finishing, mainly for the processing of quenched parts; the CNC lathe is also an automatic processing equipment, and the general shaft, rod and round type parts are processed, which has advantages for special precision requirements or small batch parts processing.
A, CNC processing technology and working principle
1. Division of process and work steps; determination of tool points and tool change points;
2. Determination of processing route; selection of processing method and determination of processing plan.
3, the reasonable selection of machine tools, the choice of different parts of the accuracy of the workpiece;
4. Installation of parts and selection of fixtures;
5. The selection of the tool and the determination of the cutting amount;
6. Process analysis of CNC machining parts and reasonable processing technology.
B, the correct operation method of CNC precision machining
First, the geometric information and process information on the CNC machined part drawing are digitized, that is, the relative movement path of the tool and the workpiece, the change of the spindle speed and the feed speed during the CNC machining, the switch of the coolant, the transformation of the workpiece and the tool, etc. And the operation, the machining program is programmed according to the specified code and format, and then the program is input into the numerical control system.
The numerical control system first performs corresponding calculations and processing according to the requirements of the program, and then issues control commands to coordinate the coordinate axes, the main shafts and the auxiliary actions to realize the relative movement of the tool and the workpiece, and automatically complete the machining of the parts.
C, the accuracy of CNC machine tools choose to consider those factors
The precision of CNC machine tools and the precision of machining process are different. They represent the two different concepts of CNC machine tools. One is the machine’s own precision and the other is the process precision it processes. These two reasons seem to be irrelevant, but they are also related.
It is wrong to regard the positional accuracy on the manufacturer’s sample or on the product certificate as the machining accuracy of the machine tool. The positional accuracy indicated on the sample or certificate is the accuracy of the machine itself, and the machining accuracy is the sum of the errors produced by various factors of the entire process system, including the tolerances allowed by the machine itself. When selecting the type, the evaluation method of the process capability kp can be referred to as the basis for selecting the accuracy.
CNC accuracy has a significant impact on the quality of the process. It is important to note that machining accuracy and machine accuracy are two different concepts. The rigidity of the machine tool directly affects the productivity and machining accuracy. The machining speed of the machining center is much higher than that of the ordinary machine tool, and the motor power is also higher than that of the ordinary machine tool of the same specification. Therefore, the rigidity of the structural design is much higher than that of the ordinary machine tool. When ordering, the process requirements, allowable torque, power, axial force and maximum feed force can be checked according to the values provided by the manufacturer.
D, how to maintain the high strength of parts in precision parts processing
The principle measures for improving the strength of parts are: using high-strength materials, heat-treating materials to improve strength and reducing internal stress, controlling the processing to reduce or eliminate micro-defects, etc.; trying to reduce the load on the parts; increasing the dangerous section of the parts The size of the section is reasonably designed to increase the moment of inertia of the section; the structure of the part is properly involved to reduce the concentration of stress.
CNC precision parts processing can be multi-coordinate linkage, can process parts with complex shapes; high processing precision and stable processing quality; mass production, product quality is easy to control; when machining parts change, generally only need to change the NC program, Save production preparation time; the machine itself has high precision and rigidity, can choose favorable processing quantity, high productivity (usually 3~5 times of ordinary machine tools); high degree of machine automation, can reduce labor intensity; professional for operators The quality requirements are lower, and the technical requirements for maintenance personnel are higher.
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