The cause and improvement of machining deformation of machine parts

1 分析机械零件加工中变形的原因

1 Analysis of the cause of deformation in machining of mechanical parts

1.1 内力作用导致零件加工精度改变

1.1 internal force action leads to the change of machining precision of parts

车床加工时，通常是利用向心力的作用，用车床的三爪或者四爪卡盘，把零件卡紧，然后对机械零件进行加工。同时，为了确保零件在受力时不松动、减小内径向力的作用，必须要使夹紧力大于机械的切削力。夹紧力随着切削力的增大而增大，随之减小而减小。这样的操作才能使机械零件在加工过程中受力稳定。但是，在三爪或者四爪卡盘松开后，加工出来的机械零件就会与原来的相差甚远，有的呈现多边形，有的呈现椭圆形，出现较大偏差。

When lathe is processed, it usually uses the action of centripetal force, and uses the three jaw or four jaw chuck of the lathe to fasten the parts and then process the mechanical parts. At the same time, in order to ensure that parts are not loose and reduce the force of internal diameter, the clamping force must be greater than the cutting force of the machine. The clamping force increases with the increase of cutting force and decreases with the increase of cutting force. Such operation can make mechanical parts stable in the process of machining. However, after the three or four claw chuck is loosened, the machined parts that are processed will be far apart from the original ones. Some are polygons, some of them appear elliptical and large deviations appear.

1.2 热处理加工后容易产生变形问题

1.2 easy to produce deformation after heat treatment

对于薄片类的机械零件，由于其长径非常大，在对其进行热处理后容易出现草帽弯曲的状况。一方面会出现中间鼓出的现象，平面偏差增大，另一方面由于各种外界因素的影响，使零件产生弯曲现象。这些变形问题的产生不仅是由于热处理后的零件内应力发生了变化，还有操作人员的专业知识不扎实，不太了解零件的结构稳定性，从而增大了零件变形的概率。

For the mechanical parts of sheet type, because of its very long diameter, it is easy to appear the bending of straw hat after heat treatment. On the one hand, there will be a phenomenon of intermediate drum, and the plane deviation will increase. On the other hand, the bending of parts will be caused by various external factors. These deformation problems are not only due to the changes in the internal stress of the parts after heat treatment, but also the professional knowledge of the operators is not solid, and the structural stability of the parts is not very well understood, thus the probability of the deformation of the parts is increased.

1.3 外力作用下引起的弹性变形

Elastic deformation caused by 1.3 external force

在机械加工中零件出现弹性形变的原因主要有几个方面。一是一些零件的内部构造中如果含有薄片，就会对操作方法有更高要求，否则在操作人员在对零件进行定位和装夹时，不能和图纸的设计之间进行对应，容易导致弹性形变的产生。二是车床和夹具的不平整，使零件在进行固定时两侧的受力不均匀，导致切割时受力作用小的一边在力的作用下就会出现平移出现零件变形。三是在加工过程中零件的定位不合理，使零件的刚性强度降低。四是切削力的存在也是引起零件弹性形变的原因之一。这些不同的原因导致的弹性形变，都说明外力作用对机械零件加工质量的影响。

There are several reasons for elastic deformation of parts during machining. First, if the internal structure of some parts contains thin slices, the operation method will have higher requirements. Otherwise, when the operators locate and clamp the parts, they can not correspond with the design of the drawings, which can easily lead to the production of elastic deformation. The two is the unevenness of the lathe and the fixture, so that the force on both sides of the parts is not uniform when the parts are fixed. Three, the location of parts is unreasonable in the process of making parts, so that the rigidity of parts is reduced. Four, the existence of cutting force is also one of the causes of elastic deformation of parts. The elastic deformation caused by these different reasons indicates the effect of external force on the machining quality of machine parts.

2 机械零件加工变形的改进措施

2 improvement measures for machining deformation of mechanical parts

在实际的零件加工中，导致零件变形的因素很多。为了从根本上解决这些变形问题，操作人员需要在实际工作中认真探索这些因素，并结合工作精要，制定改进措施。

In actual parts processing, there are many factors leading to the deformation of parts. In order to solve these deformation problems fundamentally, the operators need to explore these factors seriously in the actual work and make improvement measures in combination with the essential work of the work.

2.1 使用专用夹具，减少装夹变形

2.1 use special fixture to reduce the deformation of clamp

在机械零件加工过程中，对精细化的要求非常严格。针对不同零件，选用不同的专用工装，可以使零件在加工过程中不易出现位移。另外，加工前，工作人员还需要进行相应的准备工作，全面检查固定零件，对照图纸，检查机械零件的位置是否正确，以减少装夹变形。

In the machining process of machine parts, the requirements for refinement are very strict. For different parts, different special tooling can be used, so that parts can not be easily displaced during machining. In addition, before the processing, the staff also need to carry out the corresponding preparation work, the overall inspection of the fixed parts, control drawings, check the position of mechanical parts is correct to reduce the deformation of the clamping.

2.2 修整加工

2.2 trimming and processing

零件在经过热处理后很容易出现变形问题，这就需要采取措施来保证零件的安全性能。在机械零件加工完成并自然变形后，要运用专业的工具进行修整。在对加工后的零件进行修整加工时，需要按照行业的标准要求进行，以确保零件质量，延长其使用寿命。这种方法在零件变形后进行最为有效。如果零件经过热处理后变形，则可以在淬火之后进行回火。因为淬火之后在零件中会存在残余奥氏体，这些物质在室温下进而转化为马氏体，然后物体就会膨胀。在加工零件时要认真对待每一个细节，这样就可以降低零件变形的概率，把握好图纸上的设计理念，根据生产要求，使生产出来的产品符合标准，提高经济效益和工作效率，从而确保机械零件加工的质量。

Parts are easily deformed after heat treatment, so measures need to be taken to ensure the safety performance of parts. After machining and deforming the machine parts, it is necessary to use professional tools to repair them. When trimming parts after processing, they need to be carried out according to the standard requirements of the industry, so as to ensure the quality of parts and prolong their service life. This method is most effective after deformation of parts. If the parts are deformed after heat treatment, tempering can be achieved after quenching. Because after quenching, residual austenite will exist in the parts, which will be transformed into martensite at room temperature, and then the object will expand. When the parts are processed, every detail should be taken seriously, which can reduce the probability of the deformation of the parts, grasp the design ideas on the drawings, and make the products produced according to the production requirements to meet the standard, improve the economic efficiency and work efficiency, so as to ensure the quality of the mechanical parts.

2.3 提升毛坯质量

2.3 improve the quality of blank

在各种设备的具体操作过程中，提升毛胚的质量是防止零件变形的保证，以便加工好的零件符合零件的具体标准要求，为后期零件的使用提供保证。因此，操作人员需要检查不同的毛坯质量，对存在问题的毛胚，要及时更换，避免出现不必要的问题。同时，操作人员需要结合设备的具体要求选择可靠的毛坯，以保证经过加工后的零件质量和安全性达到标准要求，进而延长零件的使用寿命。

In the specific operation of various equipment, the improvement of the quality of the hair embryo is the guarantee to prevent the deformation of the parts, so that the machined parts meet the specific standard requirements of the parts and provide the guarantee for the use of the later parts. Therefore, operators need to check the quality of different blanks, to replace the existing problems, so as to avoid unnecessary problems. At the same time, the operators should choose the reliable blank to ensure the quality and safety of the processed parts to meet the standard requirements, and then prolong the service life of the parts.

2.4 增加零件刚度，防止过大变形

2.4 increase the stiffness of parts to prevent excessive deformation

在机械零件加工中，零件的安全性能受到很多客观因素的影响。尤其是在零件进行热处理后，由于应力收缩现象，会导致零件变形。因此，为了防止变形现象的产生，技术人员需要选择合适的限热型处理方式，进而以改变零件刚度。这需要结合零件的性能，运用合适的限热型处理措施，从而保证安全的可靠性。即使在热处理之后，也不会出现明显变形。

In the machining of mechanical parts, the safety performance of parts is influenced by many objective factors. Especially after the heat treatment of parts, due to the stress shrinkage phenomenon, the parts will deform. Therefore, in order to prevent deformation phenomenon, technicians need to choose suitable heat treatment mode to change the stiffness of parts. It is necessary to combine the performance of parts and apply appropriate heat treatment measures to ensure safety reliability. Even after heat treatment, there will be no obvious deformation.

2.5 减小夹紧力的措施

2.5 measures to reduce clamping force

在加工刚性差的零件时，需要采取一些措施增加零件的刚性程度，如可以增加辅助支撑。也要注意加紧点和零件之间的接触面积，根据零件的不同，选择不同的夹持方式，如加工薄壁套类零件时，可以选用有弹性的轴装置进行夹紧

When machining parts with poor rigidity, some measures need to be taken to increase the rigidity of parts, such as increasing auxiliary support. We should also pay attention to the contact area between the tightened and the parts, and choose different clamping methods according to the different parts. For example, when the thin-walled parts are processed, an elastic shaft device can be used for clamping.