introduction
As an advanced processing equipment, CNC lathe can bring huge economic and social benefits in practical applications. In the CNC lathe processing, the precision control of product quality is very important, especially the application of automation technology, which is more prominent than the traditional processing technology, and puts forward new requirements for the precision of CNC lathe processing in the new era. In CNC lathe machining, programming accuracy, servo accuracy and interpolation accuracy are directly related to machining accuracy. In addition, in the production and processing of CNC lathes, it will be affected by many factors such as environment, manufacturing and materials. If the deviation of lathe construction can not be effectively controlled, it will directly affect the processing quality and precision of parts, and needs further improvement.
1, the working principle of CNC lathe
As a kind of mechatronics product, CNC lathe integrates many modern technologies in practical applications, which helps to improve processing efficiency and precision. In the machining of parts for ordinary lathes, the operator needs to combine the construction drawings to change the trajectory of the workpiece. In the new era, higher requirements are placed on the machining of the workpiece. In the machining parts of CNC lathes, it is necessary to fully grasp the process parameters and processing flow, prepare the machining process through the numerical control language, and issue instructions to the servo system to realize the automatic processing and manufacturing of parts.
2. Factors affecting the machining accuracy of CNC lathes
In the process of CNC lathe processing, the influencing factors are more diverse, and the servo control method and precision are high and low, which will greatly affect the machining precision of CNC lathe, and lay a safety hazard for subsequent parts processing. In terms of machining precision of CNC lathe, the influencing factors mainly include the following aspects: 1 lathe geometric error; 2 turning tool geometric parameter error; 3 lathe thermal deformation error; 4 servo feed system error; 5 tool wear error.
In view of the factors affecting the machining accuracy of these lathes, servo feed system error and tool geometry error are common factors, which affect the processing quality of the components to a certain extent. At present, in China's CNC lathe processing, the servo motor drives the ball screw to control the machining position, and the ball screw transmission error is one of the main factors affecting the positioning accuracy of the CNC lathe. Looking at the current status of China's CNC lathes, mainly based on closed-loop control systems. In the actual operation, if the servo motor screw moves in the opposite direction, it will not only affect the machining accuracy of the parts, but also cause the CNC lathe to idle due to the occurrence of the gap, and this error is difficult to avoid [3]. Under the influence of external force, the moving parts may be elastically deformed, which increases the severity of the numerical control lathe error problem and cannot effectively control the precision of CNC lathe processing.
CNC lathes in the machining of parts, the turning tool cuts the parts in a preset motion trajectory. Due to the yaw angle and arc radius of the turning tool, a certain dimensional deviation occurs when the part is machined, and the axial dimensional change increases as the radius of the arc increases. Therefore, in the machining of parts, the change in the length of the axial displacement depends on the adjustment of the axial dimension. In the machining of parts of CNC lathes, it is necessary to comprehensively analyze the axial dimension and displacement length to optimize the machining process. It should be noted that the parameters such as the tool nose distance, the arc radius and the height of the part center will directly affect the accuracy of the part processing. The service life of the CNC lathe also depends on the grasp of these parameters, and its importance is self-evident.
3. Effective measures to improve the machining accuracy of CNC lathes
(1) Optimizing the overall design of CNC lathes
In the overall design of CNC lathes, reasonable production strategies should be selected according to the actual situation to improve the manufacturing efficiency and precision of CNC lathes. From the current development status of China's CNC lathe manufacturing enterprises, it is mainly through the design of the mainframe structure and the purchase of key functional components, which not only can improve the processing quality, but also effectively reduce the processing cost. At the same time, the overall design of the CNC lathe needs to ensure that the deformation stress is evenly distributed to each component, so as to avoid the occurrence of weak components and improve the deformation of the lathe.
For the adjustment of the center of gravity of the CNC lathe structure, the height of the center of gravity can be appropriately reduced according to the actual requirements, and the swing mode frequency can be increased without affecting the manufacturing quality of the CNC lathe. On the basis of ensuring the structural rigidity, the amount of structural materials is reduced as much as possible to effectively control the center of gravity of the machine tool. In order to effectively improve the machining precision of CNC lathe, the optimization of the hot state characteristics of the spindle system helps to improve the defects and deficiencies in the traditional process, improve the rationality of the spindle system design, improve the spindle drift phenomenon as much as possible, and control the error reasonably. Within the scope.
(2) Improve the geometric accuracy of the lathe guide
In the manufacture of CNC machine tools, the geometrical accuracy of the bed rails should be further optimized, the high-precision development goals should be clarified, and the lathe body base and rail structure design should be optimized. For the full-function CNC lathe, the design can be carried out in the form of a slant bed, and the closed cylindrical structure can reduce the dead weight and optimize the manufacturing process. Through the cylindrical structure, the CNC machine tool is used to improve the bending strength and rigidity of the bed under the cutting load, and obtain considerable geometric precision. Under normal circumstances, it is necessary to comprehensively consider the moving speed, select the guide rail with strong load capacity as much as possible, and optimize the machining process of the CNC lathe. In addition, under high-load cutting conditions, the accuracy of the CNC lathe can be improved, and the sub-structure of the inlaid steel sliding guide can be selected according to the actual situation. The injection molding material is bolted on the steel guide rail, which helps to improve the gap between the steel guide rail and the base rail, optimize the defects and deficiencies in the process, improve the machining precision of the guide rail, and provide a solid guarantee for the subsequent processing quality.
(3) Error compensation method error compensation method
As an effective system compensation method, the machining error of CNC lathe parts can be controlled within a reasonable range, and the machining accuracy can be improved by error compensation. With modern technology, high-quality and high-precision parts can be obtained while reducing the deviation of CNC lathe machining. The semi-closed-loop servo system CNC lathe is affected by the reverse deviation, and the accuracy of the lathe repeat positioning accuracy is difficult to be effectively controlled, which affects the precision and quality of the machined parts. Based on this, through the error compensation method, the machining error of the part can be controlled within a reasonable range, and the machining error of the part can be effectively compensated. As far as the current CNC lathe positioning error is concerned, most of them remain at around 0.02 mm, and there is no compensation function. With the corresponding hardware and software, the accurate positioning of the tool is realized, and the gap existing therein is eliminated as much as possible.
It does not affect the low-speed one-way positioning of the CNC lathe, and effectively interpolates the CNC lathe. In this process, for the reverse problem, the interpolation process can be performed on the basis of determining the gap value to meet the processing requirements of the part. For other CNC lathes, the built-in multiple addresses can be used for data storage to achieve axis backlash storage and compensation. By changing the direction of the lathe axis movement, the backlash value can be obtained, the coordinate displacement can be effectively compensated, the deviation can be controlled within a reasonable range, and the machining accuracy of the workpiece can be improved, laying a solid foundation for subsequent machining activities.
(4) Error prevention method
The error prevention method is an effective prevention method. It is not the treatment of errors, but prevention to avoid the occurrence of errors or to control them within a reasonable range. Through the optimization design of the machine tool, comprehensive analysis of possible error problems, as far as possible to control the error within a reasonable range. For example, according to the processing needs to improve the machining accuracy of lathe parts, the existing lathe structure is further optimized to support the subsequent part machining accuracy and rigidity. In addition, it can also effectively control the processing environment and optimize the processing technology. However, it should be noted that the error prevention method also has certain defects and deficiencies. Excessive improvement of the accuracy of the CNC lathe will not only affect the product quality, but also increase the processing cost, which is not conducive to the long-term survival and development of the enterprise.
4 Conclusion
In summary, in the production and processing of CNC lathes, it will be affected by many factors such as environment, manufacturing and materials. If the lathe construction deviation is not effectively controlled, it will affect the processing quality of parts. Therefore, it is necessary to select a reasonable range, further optimize the existing process, improve the defects and deficiencies therein, and improve the machining precision of the CNC lathe.
