How much do you know about the cause of machining deformation and how to improve?
The machinability can not only bring the economic benefit to the enterprise, but also reduce the probability of the safety accident. Therefore, it is very important to avoid the deformation of parts in the process of machining. Operators need to take into account all factors, and take appropriate measures to prevent the deformation, so that the finished parts can be used properly. In order to achieve this goal, it is necessary to analyze the causes of parts deformation and find out reliable measures,you can take a few mins to read below,thanks.
The analyze of deformation in machining parts
1.1 CHANGES IN MACHINING ACCURACY DUE TO INTERNAL FORCES
Lathe processing, is usually the role of the use of centripetal force, with three or four-claw Lathe Chuck, the parts clamped, and then on the mechanical parts processing. At the same time, it is necessary to make the clamping force greater than the mechanical cutting force in order to ensure that the parts are not loose and reduce the inner radial force. The clamping force increases with the increase of cutting force and decreases with the decrease. Such operation can make the mechanical parts in the process of stable stress. However, after the three-claw or four-claw chuck release, the machined parts will be very different from the original, some polygonal, some oval, a larger deviation.
1.2 deformation is easy to occur after Heat Treatment
For the mechanical parts of thin sheet, the straw hat is easy to bend after heat treatment because of its large length and diameter. On the one hand, there will be the phenomenon of middle bulging, plane deviation increased, on the other hand, due to the influence of various external factors, so that parts have bending phenomenon. These deformation problems are caused not only by the change of the internal stress of the parts after heat treatment, but also by the lack of professional knowledge of the operators and their lack of understanding of the structural stability of the parts, thus increasing the probability of the parts deformation.
1.3 elastic deformation caused by external forces
There are several reasons for the elastic deformation of parts in machining. First, if the internal structure of some parts contains thin sheets, there will be higher requirements on the operation method, otherwise, when the operator carries on the positioning and clamping of the parts, it can not correspond with the drawing design It is easy to cause elastic deformation. Second, the Lathe and fixture unevenness, so that parts in the fixed force on both sides of the uneven, resulting in cutting force on the side of the small force will occur under the action of translational deformation parts. Third, the positioning of the parts is unreasonable in the process of machining, so that the rigid strength of the parts is reduced. 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 all shows the influence of external force on the machining quality of mechanical parts.
Improvement Measures for machining deformation of Mechanical Parts
In the actual part processing, causes the part distortion the factor to be many. In order to fundamentally solve these problems, operators need to seriously explore these factors in the actual work, and work out improvement measures.
2.1 Use special fixture to reduce clamping distortion
In the process of machining mechanical parts, the requirements for refinement are very strict. For different parts, choose different special tooling, can make parts in the process of 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, compared with drawings, check whether the mechanical parts are in the correct position, in order to reduce clamping deformation.
It is easy to deform parts after heat treatment, so it is necessary to take measures to ensure the safety of parts. After the mechanical parts are processed and naturally deformed, they should be trimmed with professional tools. In order to ensure the quality of the parts and prolong their service life, it is necessary to carry out the trimming and processing according to the industry standard. This method is most effective after the part deforms. If the part is deformed after heat treatment, it may be tempered after quenching. Because there is retained austenite in the parts after quenching, this material is converted to Martensite at room temperature, and the object expands. When machining parts, we should take every detail seriously, so that we can reduce the probability of deformation of the parts, grasp the design concept on the drawing well, make the products meet the standards according to the production requirements, and improve the economic efficiency and work efficiency In order to ensure the quality of mechanical parts processing.
2.3 improving the quality of blanks
In the operation of various equipment, to improve the quality of the rough is to prevent the deformation of the parts, so that the processed parts meet the specific requirements of the parts to provide a guarantee for the use of later parts. Therefore, operators need to check the different quality of the rough, the existence of the problem of the rough, to replace in time, to avoid unnecessary problems. At the same time, the operator needs to select reliable blank according to the specific requirements of the equipment, in order to ensure the quality and safety of the processed parts to meet the standard requirements, and then extend the service life of the parts.
2.4 increase part stiffness to prevent excessive deformation
In the machining of mechanical parts, the safety of parts is affected by many objective factors. Especially in parts after heat treatment, due to the phenomenon of stress contraction, parts will lead to deformation. Therefore, in order to prevent the occurrence of deformation, technical personnel need to choose the appropriate heat-limiting treatment, and then to change the stiffness of parts. This needs to combine the performance of parts, the use of appropriate heat-limiting treatment measures, so as to ensure safety and reliability. Even after heat treatment, there is no obvious deformation.
2.5 MEASURES TO REDUCE CLAMPING FORCE
When machining the 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 tightening point and the parts, according to the different parts, choose different clamping methods, such as processing thin-walled sleeve parts, you can choose the elastic shaft device for clamping, pay attention to the position of tightening should choose the position of strong rigidity. But to the long axis class mechanical part, may use the two ends localization way. For very large diameter parts, both ends need to be clamped together, can not use the “one end clamping, one end hanging” approach. In addition, in the processing of CAST Iron Parts, fixture design needs to increase the cantilever part of the rigid as a principle. A new type of hydraulic clamping tool can also be used to effectively prevent the quality problems caused by clamping deformation during the machining process.
2.6 Reduced Cutting Force
In the cutting process should be closely linked to the processing requirements of attention to the cutting angle in order to reduce the cutting force. The Rake Angle and the main deflection angle of the cutter can be increased as much as possible to make the cutter sharp. For example, in the turning of thin-walled parts, if the rake angle is too large, will make the tool wedge angle become larger, speed up the wear rate, deformation and friction will be reduced, can choose the size of the rake angle according to different tools. The Rake Angle is 6 ~ 30 for high-speed cutting tools and 5 ~ 20 for carbide cutting tools.