Exploring the causes of machining deformation of mechanical parts and its improvement

Mechanical machining performance is not only related to the interests of the company, but also to safety, which can effectively reduce the probability of safety accidents while bringing economic benefits to the company. It is therefore particularly important to avoid deformation of parts during the machining process. The operator needs to consider all the factors and take appropriate measures to prevent deformation during the machining process so that the finished part can be used properly. In order to achieve this goal, it is necessary to analyse the causes of the phenomenon of deformation in the machining of parts and to identify reliable measures for the deformation of parts, with a view to laying a solid foundation for the realization of the strategic objectives of modern enterprises.

  1. Analysis of the causes of deformation in the machining of mechanical parts

1.1 The role of internal forces lead to parts processing accuracy change

When lathe processing, usually the role of centripetal force is used, with the lathe’s three-jaw or four-jaw chuck, the parts are stuck tight, and then the mechanical parts are processed. At the same time, in order to ensure that the part does not loosen when subjected to forces and to reduce the effect of internal radial forces, it is necessary to make the clamping force greater than the mechanical cutting force. The clamping force increases as the cutting force increases and then decreases as it decreases. This is the only way to ensure that the mechanical part is stable during the machining process. However, after the three-jaw or four-jaw chuck is released, the machined mechanical parts will be very different from the original, some present polygonal, some present oval, a large deviation.

1.2 Heat treatment processing is easy to produce deformation problems

For the sheet type of mechanical parts, due to its long diameter is very large, in the heat treatment of its easy to appear after the bending of the straw hat situation. On the one hand, the phenomenon of the middle bulge will appear, the plane deviation increases, on the other hand, due to the influence of various external factors, so that the parts produce bending phenomenon. These deformation problems arise not only because the internal stress of the parts after heat treatment has changed, there is also the operator’s professional knowledge is not solid, not quite understand the structural stability of the parts, thus increasing the probability of deformation of the parts.

1.3 Elastic deformation caused by the action of external forces

There are several main reasons for the elastic deformation of parts in machining. One is that if the internal structure of some parts contains thin sheets, there will be higher requirements for the method of operation, otherwise the correspondence between the operator in positioning and clamping the part and the design of the drawing cannot be carried out, which will easily lead to the generation of elastic deformation. Secondly, the unevenness of the lathe and fixture makes the part unevenly stressed on both sides when it is fixed, resulting in a small force on the side of the cut when the force is applied and the part is deformed. Thirdly, the positioning of the part in the machining process is unreasonable, which reduces the rigidity and strength of the part. Fourth, the presence of cutting forces is also a cause of elastic deformation of the part. These different causes of elastic deformation, all illustrate the effect of external forces on the quality of machining of mechanical parts.

  1. Mechanical parts processing deformation improvement measures

In the actual machining of parts, there are many factors that lead to the deformation of parts. In order to fundamentally solve these deformation problems, operators need to carefully explore these factors in practice and develop improvement measures in conjunction with the essence of their work.

2.1 Use special fixtures to reduce clamping deformation

In the machining of mechanical parts, the requirements for refinement are very strict. For different parts, the use of different special fixtures can make the parts less likely to be displaced during machining. In addition, before processing, staff also need to carry out the corresponding preparatory work, a comprehensive check of fixed parts, against the drawings, check whether the position of mechanical parts is correct, in order to reduce the clamping deformation.

2.2 Trimming processing

Parts are prone to deformation problems after heat treatment, which requires measures to ensure the safety performance of the parts. After machining and natural deformation of the mechanical part, the part is trimmed using specialist tools. When finishing the machined parts, they need to be finished in accordance with the industry’s standard requirements to ensure their quality and extend their service life. This method is most effective when carried out after the part has been deformed. If the part is deformed after heat treatment, it can be tempered after quenching. This is because after quenching there will be residual austenite in the part, which are then converted to martensite at room temperature and the object will then expand. When processing parts, every detail should be taken seriously so that the probability of deformation of the parts can be reduced, the design concept on the drawings can be grasped, and the products produced according to the production requirements can be made to meet the standards to improve economic efficiency and work efficiency, thus ensuring the quality of mechanical parts processing.

2.3 Improve the quality of the blank

During the specific operation of various equipment, upgrading the quality of the blanks is a guarantee to prevent the deformation of the parts so that the processed parts meet the specific standard requirements of the parts and provide a guarantee for the use of the parts at a later stage. The operator therefore needs to check the quality of the different blanks and replace those with problems in order to avoid unnecessary problems. At the same time, the operator needs to select reliable blanks in conjunction with the specific requirements of the equipment in order to ensure that the quality and safety of the processed parts meet the standard requirements and thus extend the service life of the parts.

2.4 Increase the stiffness of parts to prevent excessive deformation

In the machining of mechanical parts, the safety performance of the parts is influenced by many objective factors. In particular, after the heat treatment of the part, the stress contraction phenomenon can lead to the deformation of the part. In order to prevent deformation, technicians need to select a suitable heat-limited treatment to change the stiffness of the part. This is done by applying the appropriate heat-limiting treatment in conjunction with the properties of the part, thus ensuring safety and reliability. Even after heat treatment, no significant deformation occurs.

2.5 Measures to reduce clamping forces

When machining parts with poor rigidity, measures need to be taken to increase the degree of rigidity of the part, e.g. auxiliary supports can be added. Attention should also be paid to the contact area between the stepping-up point and the part, according to the different parts, choose different clamping methods, such as processing thin-walled sleeve class parts, you can choose to have a flexible shaft device for clamping, pay attention to the location of the stepping-up should choose a more rigid part. For long shafts of mechanical parts, you can use the two end positioning method. For the long diameter of very large parts, the two ends need to be clamped together, can not use “one end of the clamping, one end of the suspension” method. In addition, when machining cast iron parts, the design of the fixture needs to be based on the principle of increasing the rigidity of the cantilever section. A new hydraulic clamping tool can also be used to effectively prevent quality problems caused by clamping deformations during machining.

2.6 Reducing cutting forces

The cutting angle should be closely integrated into the machining requirements in order to reduce the cutting forces. You can try to increase the front angle and main deflection angle of the tool to make the cutting edge sharp, and a reasonable tool is also essential for the size of the turning forces in turning. For example, in the turning of thin-walled parts, if the front angle is too large, the wedge angle of the tool will become larger, speeding up the rate of wear, deformation and friction will also be reduced, and the size of the front angle can be selected according to the different tools. If you choose high-speed tools, the front angle of 6 ° ~ 30 ° best; if you use carbide tools, the front angle of 5 ° ~ 20 ° best.

  1. Conclusion

There are many factors that lead to the deformation of mechanical parts, for different reasons to take different measures to solve. In practice, we should pay attention to every detail of mechanical processing, constantly improve the production process, and strive to minimize economic losses. v1 industrial internet strictly control quality control to ensure stable work of machinery and equipment, to achieve the goal of high quality and high efficiency of mechanical processing, so as to promote the mechanical processing industry has a better development prospects and a broader market.

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