Machining performance is not only related to the interests of the enterprise, but also to safety, which can effectively reduce the probability of safety accidents while bringing economic benefits to the enterprise. Therefore, it is especially important to avoid the deformation of parts during the machining process. Operators need to consider various 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 analyze the causes of deformation in the machining of parts and to find reliable measures for the deformation of parts, with a view to laying a solid foundation for the realization of the strategic goals of modern enterprises.
First, analysis of the causes of deformation in the machining of mechanical parts
1, the role of internal forces lead to parts machining accuracy change lathe processing, usually using the role of centripetal force, with the lathe's three-jaw or four-jaw chuck, the parts stuck tight, and then the mechanical parts for processing. At the same time, in order to ensure that the parts do not loosen and reduce the role of internal radial force when the force is applied, it is necessary to make the clamping force greater than the cutting force of the machine. The clamping force increases with the increase of the cutting force and decreases with it. Such an operation can make the mechanical parts in the process of machining force stability. However, after the three-jaw or four-jaw chuck is released, the machined mechanical parts will be far from the original, some present polygonal, some present oval, a large deviation.
2, the elastic deformation caused by the action of external forces in the machining of parts in the elastic deformation of the main reasons there are several aspects. First, if the internal structure of some parts contains thin sheets, there will be higher requirements for the operation method, otherwise, when the operator is positioning and clamping the parts, it cannot correspond with the design between the drawings, which will easily lead to the generation of elastic deformation. Second, the unevenness of the lathe and fixture, so that the parts in the fixed on both sides of the force is not uniform, resulting in the cutting of the force on the side of the small role in the force will appear under the action of the translation of the parts deformation. Third, the positioning of the parts in the process is not reasonable, so that the rigid strength of the parts is reduced. Fourth, the presence of cutting forces is also a cause of elastic deformation of the part. These different reasons for the elastic deformation, all illustrate the effect of external forces on the quality of machining of mechanical parts.
3, heat treatment processing is prone to deformation problems for the thin sheet class of mechanical parts, due to its very large long diameter, in its heat treatment is prone to straw hat bending condition. On the one hand, there will be the phenomenon of the middle bulge, 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 are not only due to changes in the internal stress of the parts after heat treatment, and 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.
Second, the mechanical parts processing deformation improvement measures
In the actual processing of parts, resulting in parts deformation of many factors. In order to fundamentally solve these deformation problems, the operator needs to seriously explore these factors in the actual work, and combined with the essence of the work, the development of improvement measures.
1, enhance the quality of the blank in the specific operation process of various equipment, enhance the quality of the blank is to prevent the deformation of the parts to ensure that the processed parts meet the specific standard requirements of the parts, to provide assurance for the use of the parts later. Therefore, the operator needs to check the quality of different blanks and replace the problematic ones in time to avoid unnecessary problems. At the same time, operators need to combine the specific requirements of the equipment to choose reliable blanks to ensure that the quality and safety of the parts after processing meet the standard requirements, and thus extend the service life of the parts.
2, increase the stiffness of the parts to prevent excessive deformation in the machining of mechanical parts, the safety performance of the parts is affected by many objective factors. Especially after the heat treatment of the parts, due to the phenomenon of stress contraction, will lead to parts deformation. Therefore, in order to prevent deformation, the technician needs to choose a suitable heat-limited treatment to change the stiffness of the part. This requires the application of the appropriate heat-limiting treatment in combination with the properties of the part, thus ensuring safety and reliability. Even after heat treatment, there will be no significant deformation.
3, the use of special fixtures to reduce clamping deformation in the process of machining mechanical parts, the requirements for refinement is very strict. For different parts, the use of different special fixtures can make the parts in the process of processing is not easy to appear displacement. In addition, before processing, the 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.
4, trimming processing parts after heat treatment is easy to deformation problems, which requires measures to ensure the safety performance of the parts. In the mechanical parts after processing and natural deformation, to use professional tools for trimming. In the finishing process of the machined parts, it is necessary to follow the standard requirements of the industry to ensure the quality of the parts and extend their service life. This method is most effective when performed after the part has been deformed. If the part is deformed after heat treatment, it can be tempered after quenching. This is because residual austenite is present in the part after quenching and these substances are then converted to martensite at room temperature and the object then expands. When processing parts to treat every detail carefully, so that you can reduce the probability of parts deformation, grasp the design concept on the drawings, according to the production requirements, so that the products produced to meet the standards, improve economic efficiency and efficiency, so as to ensure the quality of mechanical parts processing.
5, measures to reduce the clamping force in the processing of poorly rigid parts, you need to take some measures to increase the degree of rigidity of the parts, such as you can increase the auxiliary support. Attention should also be paid to the contact area between the stepping-up point and the parts, according to the different parts, choose different clamping methods, such as processing thin-walled set of parts, you can choose a flexible shaft device for clamping, pay attention to the location of the stepping-up should choose a more rigid part. And for long shaft type of mechanical parts, you can use the two end positioning method. For the very large diameter parts, the need to use the two ends of the clamping method, 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 should be based on the principle of increasing the rigidity of the cantilevered part. Can also use a new hydraulic clamping tool to effectively prevent the parts in the process of clamping deformation caused by quality problems.
6, reduce the cutting force in the cutting process should be closely combined with the processing requirements to pay attention to the cutting angle in order to reduce the cutting force. You can try to increase the front angle of the tool and the main deflection angle, so that the cutting edge sharp, and a reasonable tool in the turning of the size of the turning force is also critical. For example, in the turning of thin-walled parts, if the front angle is too large, it will make the wedge angle of the tool larger, speed up the wear rate, 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 is 6 ° to 30 ° best; if you use carbide tools, the front angle is 5 ° to 20 ° best.