Due to the complexity of CNC precision machining (such as different machine tools, different materials, different cutting tools, different cutting methods, different parameter settings, etc.), decided to engage in CNC precision machining (whether precision machining or programming) to reach a certain level, must go through a relatively long period of time, this manual is the engineers summed up in the long-term actual production process, the CNC precision machining technology, process, selection of common tool parameters, monitoring the process, and so on. Precision machining process, process, the selection of common tool parameters, precision machining process monitoring and other aspects of some of the experience of the General Assembly, for your reference.
First, Q: How to divide the precision machining process?
A: CNC precision machining process can be divided generally according to the following methods:
(1) tool focused sub-sequence method is to divide the process according to the tool used, with the same tool to finish machining all parts on the part can be completed. In the second knife, the third to complete the other parts they can complete. This reduces the number of tool changes, compressed air time, reducing unnecessary positioning errors.
(2) to processing parts sub-order method for precision machining of many parts, according to its structural characteristics of precision machining part into several parts, such as internal shape, shape, surface or plane. Generally first precision machining plane, positioning surface, and then processing holes; first processing simple geometry, and then processing complex geometry; first processing parts with lower precision, and then processing parts with higher precision requirements.
(3) to roughing, finishing sub-processing method for parts susceptible to machining deformation, due to possible deformation after rough machining and the need for calibration, so generally speaking, where roughing, finishing are to be separated from the process.
In summary, in the division of the process, must be depending on the structure of the parts and process, the function of the machine tool, the number of parts CNC machining content, the number of installations and the unit’s production organisation to grasp the flexibility of the situation. Another proposal to use the principle of process concentration or the principle of process dispersion, according to the actual situation to determine, but must strive to be reasonable.
Second, Q: processing order should be arranged in accordance with what principles?
A: The machining sequence should be arranged according to the structure of the part and the condition of the blank, as well as the need for positioning and clamping to consider, focusing on the rigidity of the workpiece is not destroyed. The sequence should generally be carried out in accordance with the following principles:
(1) The processing of the previous process can not affect the positioning and clamping of the next process, interspersed with general-purpose machine tool machining processes should also be considered comprehensively.
(2) The first internal cavity plus process, followed by the shape of the machining process.
(3) to the same positioning, clamping mode or the same knife machining process is best to connect to reduce the number of repetitive positioning, the number of times the tool change and the number of times to move the pressure plate.
(4) in the same installation of multiple processes, should be arranged first on the workpiece rigidity of small damage to the process.
Third, Q: workpiece clamping mode should pay attention to the determination of those aspects?
A: In determining the positioning reference and clamping programme should pay attention to the following three points:
(1) strive to design, process, and programming calculations of the benchmark unity.
(2) minimise the number of clamping, as far as possible to achieve a positioning can be machined after all the surfaces to be machined.
(3) Avoid the use of occupation machine manual adjustment programme.
(4) fixture to open and smooth, its positioning, clamping mechanism can not affect the machining of the tool (such as collision), encountered such cases, can be used with a vise or add the bottom plate to draw the screws of the clamping method.
Fourth, Q: How to determine the tool point is more reasonable? What is the relationship between the workpiece coordinate system and programming coordinate system?
- tool point can be located in the processed parts on, but note that the tool point must be the reference position or has been finishing parts, sometimes in the first process after the tool point is destroyed by processing, will lead to the second process and after the tool point to find, therefore, in the first process of tooling, note that in the positioning of benchmarks with a relatively fixed size of the relationship between the establishment of a relative position of tooling, so that according to the relative position of the relationship between them This can be based on the relative position between them to find the original tool setting point. This relative to the tool position is usually located on the machine table or fixture. Its selection principles are as follows:
(1) easy to find the right.
(2) programming convenience.
(3) tool setting error is small.
(4) easy to check when machining.
- The origin position of the workpiece coordinate system is set by the operator himself, which is determined by tool setting after the workpiece is clamped, and it reflects the distance and position relationship between the workpiece and the zero point of the machine tool. Once the workpiece coordinate system is fixed, it is generally not changed. Workpiece coordinate system and programming coordinate system must be unified, that is, in the processing, the workpiece coordinate system and programming coordinate system.