Discussion on nc turning technology of thin-walled parts

NC lathe machining of thin-walled parts is often faced with high difficulty, and it is also very easy to have abnormal problems in the process of machining, affecting the final machining accuracy, which requires great attention. This article focuses on the application of NC lathe machining process of thin-walled parts. First, it briefly introduces thin-walled parts and their machining requirements, then analyzes the common problems that should be paid close attention to in the process of NC lathe machining of thin-walled parts, and finally discusses how to optimize the corresponding machining process, hoping to have a reference role.

In the development of China’s industrial production at this stage, the application of thin-walled parts is becoming more and more popular, and has shown obvious advantages in practical applications. It solves the problems and limitations of the use of thicker parts in the past, which should be paid close attention to. However, it is difficult to process thin-walled parts, and there are also many influencing factors, which will inevitably affect the machining accuracy of thin-walled parts, and may have adverse effects on subsequent applications. This also requires in-depth and detailed inspection around the NC lathe processing technology of thin-walled parts, so as to better improve the processing level, ensure that the follow-up thin-walled parts can form a more ideal optimal application effect, and solve the problems in the processing level. Relevant research is extremely necessary.

1. Thin wall parts and their processing characteristics

Thin wall parts are also parts with relatively thin walls. These parts are indispensable in the current industrial development of our country and become important parts that cannot be ignored. Especially in the field of automobile manufacturing and military industry, thin wall parts play an important role. For the practical application of thin-walled parts, although their thin walls do have obvious application advantages and solve many problems existing in the past industrial production, it is precisely because of their thin walls that some obvious hidden dangers and problems are easy to occur, especially the adverse effects caused by insufficient strength and anti deformation ability, which need to be attached great importance to and strive to adopt a variety of appropriate and reasonable ways to solve, Ensure that thin-walled parts can have ideal application performance.
In order to better optimize the application performance of thin-walled parts, it is an important means to start from processing. It is required to use more advanced and appropriate processing technology to promote the thin-walled parts to form more ideal performance on the basis of meeting the size index, and reduce the failure problems that may occur in subsequent applications. At the present stage, thin-walled parts are mainly processed by CNC lathe. The application of this process mainly involves three links: design and programming, processing and finished product inspection. Technicians are required to strictly control these three stages, so as to better meet the requirements of thin-walled parts processing and manufacturing and solve possible serious processing problems. Although the application of NC lathe processing technology in thin-walled parts does show obvious advantages, effectively reducing the working pressure of the processing personnel, there are also many difficulties in the actual application, especially in the face of higher requirements for thin-walled parts processing, it is necessary to increase management and control, so as to promote more accurate and reliable cutting tools, cutting processes and clamping treatment, Finally, while effectively controlling the deformation problem of thin-walled parts, it can promote their ideal value in subsequent applications to avoid functional damage.

2. Common problems in NC turning process of thin-walled parts

2.1 Improper design and programming

The application of NC lathe processing technology for thin-walled parts puts forward higher requirements for the preliminary design and programming. Because the design and programming are not reasonable enough, the processing requirements for thin-walled parts are not accurately mastered, and the characteristics of thin-walled parts are lack of in-depth analysis, it is likely that the design and programming scheme does not have ideal feasibility effect, which will affect the subsequent NC lathe processing effect. Because it is relatively difficult for thin-walled parts to be processed by CNC lathe, thin-walled parts themselves also show a high degree of specificity, which puts forward higher requirements for processing accuracy. Therefore, it is necessary to do a good job in the preliminary design and programming, and it is required to ensure that the corresponding design and programming are more reasonable and feasible. However, in the actual work, because of the difficulty of design and programming, there is also a lot of parameter information that needs to be set, so it is easy to have some deviation problems in the design and programming scheme. Relying on the results for subsequent CNC turning, there will inevitably be serious quality defects, which will become the source problem that needs to be solved urgently.

2.2 Thermal deformation

Thin wall parts are prone to deformation during NC turning, which is also an important reason why it is difficult to form ideal application effect for subsequent thin wall parts. It is required to prevent and control from multiple perspectives. Based on the analysis of the deformation problems of thin-walled parts in NC turning, thermal deformation is a key factor that can not be ignored, and it is also an almost inevitable important reason, which should be highly valued by turning workers. In the process of nc turning thin-walled parts, with the corresponding parts cutting processing, it is bound to produce the corresponding heat, and these cutting heat on thin-walled parts, it is very easy to cause deformation problems. From the perspective of specific thin-walled parts in the process of NC turning, whether in the fine turning, semi fine turning or rough turning treatment, there will be accompanied by the emergence of heat, which will also have an impact on thin-walled parts, resulting in their obvious deformation under the effect of thermal stress, which can not achieve the desired accuracy. It can be seen that the thermal deformation problem in NC turning of thin-walled parts not only has a bad impact, but also exists objectively and inevitably, which requires high attention.

2.3 Stress deformation

The deformation of thin-walled parts in NC lathe processing must also be related to the force, because the lack of control over the force in the processing process is likely to have a negative impact on thin-walled parts. In addition, the corresponding parts are relatively thin, so it is easy to have deformation problems under the force, which will affect the final processing and production effect. In the process of NC turning thin-walled parts, the external force often appears in many aspects and processes, such as in the application of the three jaw chuck. Because thin-walled parts need to be clamped, it is likely to cause deformation risk under this force, and it will also have an impact on the subsequent NC turning, leading to problems in the machining allowance, which can not reach an ideal accurate value. Because thin-walled parts are processed when the three jaw chuck is clamped, at this time, thin-walled parts are under stress, and their own shapes are changing. If processing is carried out under this background, the final processing effect will be affected. After the three jaw chuck is removed, the thin-walled parts will return to their original state, resulting in unsatisfactory processing results and errors.

2.4 Vibration deformation

The problems in NC lathe machining of thin-walled parts are also manifested in vibration deformation, which is also an important factor affecting the final application effect of thin-walled parts, and there are many problems in the whole machining process, which should be paid enough attention. In the process of NC turning thin-walled parts, because of the cutting effect and the thin wall of the corresponding cutting part, it is very easy to have obvious vibration. Under the vibration, it is also likely to cause abnormal changes in thin-walled parts, affecting the accuracy of subsequent processing. The appearance of this vibration effect is mainly related to the radial cutting force that occurs when thin-walled parts are cut. It should be paid active attention in the specific operation, so as to control the vibration factors from the prevention and control of force, ensure the orderly implementation of the NC turning process of thin-walled parts, and prevent the vibration deformation of thin-walled parts.

2.5 Improper operation

The problems existing in the processing of thin-walled parts by numerical control lathe workers are also specifically reflected in the operation level. Because the relevant personnel of numerical control lathe workers do not have high comprehensive quality and executive ability, some obvious deviation problems are easy to occur in the processing, which will inevitably lead to inaccurate processing of thin-walled parts and various defects. For example, the appearance of the above-mentioned deformation problems is not only closely related to some inevitable factors, but also often related to the lathe workers. Because the corresponding personnel can not form accurate operations, and the prevention and control of all aspects of deviation problems are not in place, it is very likely to increase the degree of deformation, which seriously affects the application effect of subsequent thin-walled parts. Of course, if NC lathe workers do not have a high degree of investment when participating in the processing of thin-walled parts, and they show obvious carelessness and fluke mentality in the processing process, it will also seriously affect their own work execution effect, and even increase the risk of safety accidents, which is also a key issue that cannot be ignored.

3. Optimization strategy of NC turning process for thin-walled parts

3.1 Optimization design programming

The application of NC lathe processing technology for thin-walled parts must first pay attention to the design and programming link, which is required to ensure that the design and programming are more reasonable and feasible, so as to achieve orderly guidance for subsequent processing operations. Because the thin-walled parts are relatively difficult to process, and the accuracy requirements are also demanding, it is necessary to ensure that the design and programming are more sophisticated, and it is extremely necessary to do a good job in the early stage of thin-walled parts’ characteristics analysis. In the design and programming of thin-walled parts before NC lathe machining, technicians need to first define the corresponding processing requirements, accurately master the degree of wall thickness and other relevant parameters, so as to define the requirements of relevant parameter settings, and promote them to show a stronger pertinence. In order to ensure that the machining accuracy of thin-walled parts can be guaranteed, it is often necessary to focus on the appropriate application of CNC system. For example, in the most common application of FANUC0i CNC system, it is necessary to reasonably set and select G76 compound thread cutting cycle or G92 thread turning cycle command in combination with the machining accuracy requirements of thin-walled parts, so as to enable it to show strong adaptability to thin-walled parts, Then, better optimize the follow-up execution effect, and prevent the deformation or accuracy failure caused by improper turning. After the completion of the design and programming work, it is often necessary to do a good job in the corresponding calibration work, which requires a comprehensive and detailed inspection, and timely repair the problems with anomalies and deviations, so as to maximize its scientific guidance for subsequent processing operations.

3.2 Preferred tool

The application of NC turning process for thin-walled parts puts forward higher requirements for the use of tools. If the tool is not properly selected or there is an inadaptability problem in the subsequent application, the final cutting effect will be seriously affected and the machining accuracy of thin-walled parts will be endangered. When selecting tools, technicians should focus on different aspects of thin-walled parts processing, and select the most appropriate and reasonable tools based on different processes. For example, in the rough turning and fine turning of the outer circle of thin-walled parts, 90 ° carbide turning tool can be used. However, if the turning tool for thread is selected, the machine clamp tool should be used to better ensure the accuracy of subsequent cutting. Even if there is damage, it can be replaced in time. The boring cutter used in thin-walled parts processing should also be optimized. It is required to select a suitable and reasonable machine clamping cutter as far as possible, so that it can be conveniently used in the whole processing process, without serious vibration problems, so as to control the vibration deformation problems commonly seen in previous processing. Of course, in the NC lathe processing of thin-walled parts, in addition to selecting appropriate and reasonable tools, attention should always be paid to the use of other auxiliary facilities, because thin-walled parts are prone to deformation under external forces, thus avoiding the random use of three jaw chucks. The clamping device should be flexibly used in combination with the actual situation, so as to better achieve the prevention and control of adverse forces, Ensure the orderly processing and production of thin-walled parts.

3.3 Strictly control cutting parameters

In the application of NC turning process for thin-walled parts, it is also necessary to focus on the fine control of cutting parameters to avoid adverse effects in all aspects due to improper cutting, especially for the role of heat and cutting force, which needs to be checked through reasonable control of cutting parameters. For example, in terms of the control of cutting depth, it is required to reduce the cutting depth as much as possible in the process of machining, so as to better control the cutting force and avoid the deformation of thin-walled parts due to the obvious force generated by the excessive single cutting depth. The cutting speed should also be strictly controlled. According to the specific cutting requirements, a more reasonable cutting speed should be set to avoid excessive heat generated in the cutting process due to too fast cutting speed, which will lead to thermal deformation of thin-walled parts. Of course, the whole cutting process needs to be checked in real time. It is required to ensure that the cutting process is standardized and reliable, avoid many misoperations in the cutting process, and ultimately better ensure the cutting accuracy.

3.4 Strictly control the process

The application of NC lathe processing technology for thin-walled parts also needs to focus on the strict control of each process. It is required to ensure that the process execution is relatively standardized and orderly, and can strictly follow the designed process route, so as to avoid serious deviation problems in the processing process and effectively ensure the final NC lathe processing accuracy. NC lathe workers should focus on the planned process route, and do a good job of simulation check in advance, so that they can fine control the actual processing, ensure that the corresponding thin-walled parts can be effectively controlled, so as to better avoid possible processing defects and hidden dangers. From the perspective of large process control, there is often no high difficulty, and it is only necessary to strictly follow the set procedures. However, specific processes still need to be carefully checked in each processing link, so as to promote the application of these processes to be more appropriate and reasonable. It is possible to carry out targeted analysis in combination with different parts of different parts to ensure that the process arrangement can maximize the processing accuracy. For example, when it comes to the finishing treatment of different parts of thin-walled parts, the setting of corresponding processes needs to be paid close attention to. It is required to ensure that the corresponding processes are appropriate and reasonable, and can fully analyze the processing requirements of the corresponding parts, so as to set the most reasonable finishing process, and ensure that the corresponding sequence can achieve the accuracy control of the parts.

3.5 Standardize the lathe operator’s operation

The application of NC lathe processing technology for thin-walled parts must also be implemented to the specific operation level. It is required to ensure that the NC lathe processing operation is more accurate and reliable, so as to better control the final processing accuracy. From the perspective of standard control of CNC lathe workers’ operation, the core work is to avoid the impact of human factors and ensure that lathe workers’ operation is more precise and accurate. This also requires that all CNC lathe workers should be strictly checked first to ensure that the corresponding technicians can have high comprehensive quality and ability, and have good competence in the process of CNC lathe machining. Especially when facing the relatively complex and demanding processing task of thin-walled parts, it is necessary to show the ideal operating ability, and it is strictly prohibited that any personnel without corresponding ability participate in it. When the specific NC lathe workers participate in the processing work, they often need to focus on the training work, which requires them to be familiar with the corresponding NC lathe, be able to specify the processing requirements for thin-walled parts, accurately master the setting and application of various parameters, and have a high awareness of quality assurance, so as to avoid the processing quality defects of thin-walled parts caused by any deviation problems. For thin-walled parts that have been processed and manufactured, it is also necessary to carry out fine inspection and analysis, do a good job of finished product inspection, and deal with the quality defects found in a timely manner to ensure the last pass.

4. Conclusion

To sum up, thin-walled parts are faced with high difficulties in processing, and the probability of deformation and other quality defects during processing is also relatively high. Therefore, it is necessary to focus on comprehensive protection and check. On the basis of optimizing the design and programming scheme, gradually standardize the processing processes and procedures of various CNC lathe workers, improve the quality awareness of operators, and then after completing the finished product inspection, Better control of final processing quality.
Author: Zhang Weiwei, Lu Manman, Zhang Xixi

Source: China machining solutions provider – Yaang Pipe Industry (www.machinedsgn.com)
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