We all know that the main structural parts of excavators are elongated arms, which are usually welded. The elongated arm will change its shape after welding, that is, welding deformation, which will seriously affect the effect of later use of components. So what are the main forms and causes of welding deformation of elongated arms? Today, excavator lengthening arm manufacturers will take you to learn the following related content!

　　加长臂焊接使用钢板厚度大部分在4～100mm之间，板厚规格跨度非常大，相应所采用的焊接工艺参数变化范围较大，导致焊接热出入及焊接热温度场的不均匀。因而如果在焊接过程中控制不当，焊接变形会很大，严重影响了挖掘机加长臂的加工质量以及整机的装配性。变形的基本类型有横向、纵向收缩，角变形，弯曲和波浪变形。

　　The thickness of the steel plate used in the elongated arm welding is mostly between 4 and 100 mm, and the gauge span of the plate thickness is very large. The welding process parameters adopted correspondingly vary widely, which results in the uneven heat input and exit of the welding and the thermal temperature field of the welding. Therefore, if the welding process is not properly controlled, the welding deformation will be very large, which seriously affects the processing quality of the excavator's elongated arm and the assembly of the whole machine. The basic types of deformation are transverse and longitudinal contraction, angular deformation, bending and wave deformation.

　　挖掘机结构件产生焊接变形的主要原因有：

　　The main reasons for welding deformation of excavator structural parts are as follows:

　　（1）结构型式设计不当，焊接时容易发生变形；

　　(1) Structural design is inappropriate and easy to deform during welding.

　　（2）焊接接头的型式、焊缝布置不合理；

　　(2) The type of welding joint and the arrangement of welding seam are unreasonable.

　　（3）控制焊接变形的工艺方法应用不当。

　　(3) improper application of process methods to control welding deformation.

　　对于控制挖掘机加长臂焊接变形的技术方法：

　　For the technical method of controlling the welding deformation of the elongated arm of excavator:

　　(1)采用焊接变形控制技术

　　(1) Welding Deformation Control Technology

　　合理选择施焊方法和焊接工艺参数，应围绕结构中性轴平衡布置焊缝，合理选择焊接顺序，使用分段倒退焊和间断焊，预置反变形量，采用刚性固定等。对已经出现的变形常采用机械矫正和火焰矫正法，这些变形预防措施和矫正工艺主要是依靠经验和有限的试验数据，不能适应复杂多变的结构型式和焊接方法，而且焊接变形的矫正极为耗时、费力，甚导致产品报废。

　　Reasonable selection of welding methods and welding parameters should be based on balanced arrangement of welds around the neutral axis of the structure, rational selection of welding sequence, use of step backward welding and intermittent welding, pre-set reverse deformation, rigid fixing, etc. Mechanical and flame correction methods are often used to correct the existing deformation. These deformation prevention measures and correction techniques mainly rely on experience and limited experimental data, and can not adapt to complex and changeable structural types and welding methods. Moreover, the correction of welding deformation is time-consuming and laborious, and even leads to the scrap of products.

　　(2)应用焊接变形预测方法

　　(2) Application of Welding Deformation Prediction Method

　　焊接数值模拟可通过对复杂或不可观察的焊接现象进行模拟和对极端情况下尚不知的规则进行预测，以弄清焊接过程的规律。数值模拟作为一种强有力的定量研究手段，不仅可以用来帮助理解焊接现象的本质，预测残余应力和变形，还可以此为工具，研究控制和减小残余应力，优化焊缝质量。

　　The numerical simulation of welding can make clear the rule of welding process by simulating complex or unobservable welding phenomena and predicting unknown rules in extreme cases. As a powerful quantitative research tool, numerical simulation can not only help to understand the nature of welding phenomena and predict residual stress and deformation, but also be used as a tool to study the control and reduction of residual stress and optimize the quality of weld.

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