一、滚道使用中焊缝开裂问题的分析
1、 Analysis of weld cracking in raceway
混凝土搅拌车滚道在使用中常出现焊缝开裂的问题。究其原因，主要有以下几个方面：
The problem of weld cracking often occurs in the raceway of concrete mixer. The main reasons are as follows:
1.滚道与罐体分别采用不同的材料，含碳量相差较大，且焊后未进行热处理，导致在靠近滚道一侧出现裂缝。方法：更换滚道材质。例如，当罐体采用Q345板材时，滚道也相应采用Q345材料。这样，滚道与罐体材料一样，焊接性能较好。
1. The raceway and tank body are made of different materials, the carbon content varies greatly, and no heat treatment is carried out after welding, resulting in cracks on the side close to the raceway. Solution: replace the raceway material. For example, when the can body adopts Q345 plate, the raceway also adopts Q345 material accordingly. In this way, the raceway is the same as the tank material, and the welding performance is better.
2.滚道截面的径向高度尺寸小、挠度小，或者搅拌罐的刚度低，在使用过程中易产生弹性变形，使罐体与滚道的焊缝连续承受交变应力，导致开裂。裂缝在靠近罐体后部的一侧。方法：增大混凝土搅拌车滚道截面的径向高度。
2. The radial height dimension of the raceway section is small, the deflection is small, or the stiffness of the mixing tank is low, which is easy to produce elastic deformation during use, so that the weld between the tank body and the raceway can continuously bear alternating stress, resulting in cracking. The crack is on the side near the rear of the can body. Solution: increase the radial height of the raceway section of the concrete mixer.

3.滚道和罐筒材料厚度相差极大，焊接工艺控制不好，容易导致焊缝或罐体开裂。例如，当焊接电流过大时，罐筒处就会形成咬边现象，容易导致罐皮开裂；或者当焊缝焊偏时，滚道和罐体的熔合面过大或过小，受力不均导致焊缝开裂或罐体开裂。方法：控制好焊接时的焊接形式、工艺参数和焊接位置，较好采用埋弧焊接工艺。
3. The material thickness of raceway and tank barrel varies greatly, and the welding process is not well controlled, which is easy to lead to weld or tank cracking. For example, when the welding current is too large, undercut will be formed at the tank barrel, which is easy to cause cracking of the tank skin; Or when the welding seam is biased, the fusion surface between the raceway and the tank body is too large or too small, and the stress is uneven, resulting in weld cracking or tank cracking. Solution: control the welding form, process parameters and welding position during welding, and better adopt submerged arc welding process.
二、滚道的加强方案
2、 Strengthening scheme of raceway
除了以上几种混凝土搅拌车滚道焊缝开裂的常规方法以外，我们还可以从另一个方面考虑，就是对混凝土搅拌车滚道与罐筒的焊接处进行加强。即：在罐筒内壁上增加加强环能够有效提高滚道处罐体强度和刚度，有效分散滚道处罐体的集中载荷，提高罐体的承载能力，减少罐体与滚道连接处焊缝开焊及滚道处罐皮开裂事故。
In addition to the above conventional methods to solve the weld cracking of concrete mixer raceway, we can also consider from another aspect, that is, strengthening the weld between concrete mixer raceway and tank barrel. That is, adding a reinforcing ring on the inner wall of the tank can effectively improve the strength and stiffness of the tank at the raceway, effectively disperse the concentrated load of the tank at the raceway, improve the bearing capacity of the tank, and reduce the weld opening at the connection between the tank and the raceway and the cracking accident of the tank skin at the raceway.