Cause Of Machining Deformation Of Mechanical Parts
1. Analyze The Causes Of Deformation During Machining Of Mechanical Parts
1.1 Change Of Machining Accuracy Of Parts Due To Internal Force
In the process Machining Deformation Of Mechanical Parts of lathe machining, it is usually to use the centripetal force to clamp the parts with the three-jaw or four-jaw chuck of the lathe, and then process the mechanical parts. At the same time, in order to ensure that the parts do not loosen under the force and reduce the effect of the internal force, the clamping force must be greater than the mechanical cutting force. The clamping force increases with the increase of cutting force and decreases with it. Such operation can make the mechanical parts stable in the process of processing. However, after the three-jaw or four-jaw chuck is released, the machined mechanical parts will be far different from the original ones, some will be polygonal, some will be elliptical, and there will be large deviation.
1.2 Deformation Is Easy To Occur After Heat Treatment
As for the thin mechanical parts, due to their large length and diameter, the straw cap is prone to bend after heat treatment. On the one hand, the phenomenon of bulge in the middle will occur, and the plane deviation will increase. On the other hand, due to the influence of various external factors, the parts will be bent. These deformation problems are not only caused by the change of the internal stress of the parts after heat treatment, but also because the operator’s professional knowledge is not solid enough to understand the structural stability of the parts, which increases the probability of the parts deformation.
1.3 Elastic Deformation Caused By External Force
There are several main reasons for elastic deformation of parts in machining. First, if the internal structure of some parts contains flakes, it will have higher requirements on the operation method. Otherwise, when the operators locate and clamp the parts, they cannot correspond with the design of the drawing, which is easy to cause elastic deformation. The second is the unevenness of the lathe and fixture, which makes the force on both sides of the part uneven when fixing, resulting in the translation and deformation of the part under the action of the force on the side with small force during cutting. The third is that the positioning of the parts is unreasonable during the processing, which reduces the rigidity and strength of the parts. Fourth, the existence of cutting force is also one of the causes of elastic deformation of parts. The elastic deformation caused by these different reasons shows the influence of external force on the machining quality of mechanical Plastic small batch parts.
2 Improvement Measures For Machining Deformation Of Mechanical Parts
In actual part processing, there are many factors that lead to part deformation. In order to fundamentally solve these deformation problems, operators need to carefully explore these factors in actual work and formulate improvement measures in combination with the essence of work.
2.1 Use Special Fixture To Reduce Clamping Deformation
In the process of machining mechanical parts, the requirements for refinement are very strict. For different parts, different special tooling can be selected to make the parts less prone to displacement during processing. In addition, before processing, the staff also need to make corresponding preparations, comprehensively check the fixed parts, check whether the position of the mechanical parts is correct according to the drawings, so as to reduce clamping deformation.
Parts are prone to deformation after heat treatment, which requires measures to ensure the safety performance of parts. After the mechanical parts are processed and naturally deformed, professional tools shall be used for trimming. When finishing the processed parts, it is necessary to follow the requirements of industry standards to ensure the quality of parts and extend their service life. This method is most effective after the part is deformed. If the part is deformed after heat treatment, it can be tempered after quenching. Because there will be residual austenite in the parts after quenching, these substances will be converted into martensite at room temperature, and then the object will expand. When processing parts, we should take every detail seriously, so that we can reduce the probability of deformation of parts, grasp the design concept on the drawing, make the produced products meet the standard according to the production requirements, improve economic efficiency and work efficiency, and ensure the quality of mechanical parts processing.
2.3 Improve The Quality Of Blank
In the specific operation process of various equipment, improving the quality of the rough embryo is the guarantee to prevent the deformation of the parts, so that the processed parts meet the specific standard requirements of the parts, and provide guarantee for the use of the parts in the later stage. Therefore, operators need to check the quality of different blanks, and replace the defective blanks in time to avoid unnecessary problems. At the same time, the operator needs to select reliable blanks according to the specific requirements of the equipment to ensure that the quality and safety of the processed parts meet the standard requirements, thus extending the service life of the parts.
2.4 Increase The Rigidity Of Parts To Prevent Excessive Deformation
In the processing of mechanical parts, the safety performance of parts is affected by many objective factors. Especially after the heat treatment of the parts, due to the stress shrinkage phenomenon, the parts will be deformed. Therefore, in order to prevent the occurrence of deformation, technicians need to select appropriate heat-limiting treatment methods to change the stiffness of parts. It is necessary to combine the performance of parts and apply appropriate heat-limiting treatment measures to ensure safety and reliability. Even after heat treatment, there will be no obvious deformation.
2.5 Measures To Reduce Clamping Force
When machining parts with poor rigidity, some measures should be taken to increase the rigidity of the parts, such as adding auxiliary support. Also pay attention to the contact area between the clamping point and the parts, and select different clamping methods according to the different parts. For example, when processing thin-walled sleeve parts, you can select elastic shaft device for clamping, and note that the tightening position should select the position with strong rigidity. For mechanical parts with long shafts, both ends can be positioned. For parts with very large length and diameter, both ends need to be clamped together, instead of “one end clamped, one end suspended”. In addition, when machining cast iron parts, the fixture design should be based on the principle of increasing the rigidity of the cantilever part. A new type of hydraulic clamping tool can also be used to effectively prevent quality problems caused by clamping deformation of parts during processing.
2.6 Reduce Cutting Force
In the process of cutting, we should pay attention to the cutting angle in close combination with the processing requirements in order to reduce the cutting force. The rake angle and main deflection angle of the tool can be increased as much as possible to make the blade sharp, and a reasonable tool is also crucial to the size of turning force in turning. For example, in turning thin-walled parts, if the rake angle is too large, the wedge angle of the tool will become larger, the wear speed will be accelerated, and the deformation and friction force will also be reduced. The size of the rake angle can be selected according to different tools. If high-speed tool is selected, the best rake angle is 6 °~30 °; If cemented carbide tools are used, the best rake angle is 5 °~20 °.
There are many factors that lead to the deformation of mechanical parts, and different measures should be taken to solve different reasons. In practical operation, we should pay attention to every detail of machining, constantly improve the production process, and strive to minimize the economic losses, so as to ensure the stable operation of mechanical equipment, achieve the goal of high quality and efficiency of machining, so as to promote the machining industry to have a better development prospect and a broader market.