Tube mill hollow shaft crack treatment of several key points

Tube mill hollow shaft crack treatment of several key points - 2019 02 - 21 Wang Zhanguang ( Jiaozuo strong cement) More than one, the reason of crack of hollow shaft crack occurred in R area, because it is easy to produce casting defects, such as the machined and often leave knife, stress concentration is obvious; At the same time it is bigger, the alternating stress fatigue, fatigue crack is produced. Second, the crack treatment need to grasp the key 1. Found after crack, must stop as early as possible, avoid the crack expand, or accident expanding. 2. After downtime to check the location of the crack, length, depth, and determine the cause of the cracks are analyzed. Make maintenance plan. 3. Detection of hollow shaft end face and the radial runout, control standard, determine whether beyond the standard range. If the crack depth is shallow, such as less than a third of the thickness and length within one meter, can be directly take crack welding processing. Welding measures can be seen below. 4. 506 electrode welding available. Requirements and Ann electrode drying, but also increases with the increasing drying. 5. Slow ZhuanMo machine, radial runout of hollow shaft for testing, and make records. 6. Turn to welding position to convenient operation of the first position, will stay clean up the welding position. Gas first plane from central crack, the crack plane, dig until there is no crack, the crack through the plane to two-thirds of the parent metal thickness, digging length is 100 mm or so, if the crack length is long, but every 500 mm open a plane, but need to dig a welding section, to prevent crack expanding. 7. For digging, need to grind the plane mouth to leak metallic luster, and then welding, welding, pay attention to each layer welding, want to tap on a weld to release stress and welding current is not big, can guarantee with the parent metal melting and can. 8. Above the discontinuous welding, one is to prevent crack expanding, the second is to prepare for the next comprehensive digging weld, three is a bigger contraction in order to prevent large area during welding, influence of hollow shaft. 9. Discontinuous welding is completed, the first slow ZhuanMo machine, hollow shaft radial runout, if no problem, can be fully digging, the crack and welding according to the above method. Among welding should monitor the beating of the hollow shaft, if have no problem to continue to welding, until full welding. 10. Internal crack after completion of welding, grinding template making, achieve to degrees. 11. Inside weld ends, the detection of hollow shaft radial runout, without question, open crack of the lateral plane, in turn, welding and reach full welding, grinding weld meet precision requirement. 12. Inside and outside welds all over, the hollow axial-radial beating check, ensure that three times less than the standard. Finally on weld inspection, not under ultrasonic level requirements. 13. Other details: a beating, if hollow shaft of welding is too big, should stop welding, the implementation of the welding, in order to achieve the purpose of the anti deformation. During welding, should be continuously, guarantee the welding interlayer temperature, and to take measures against wind, proper cotton insulation, and to prevent a sharp contraction and cracks. Three, the conclusion in this paper, only the interpretation of the hollow shaft crack point to remind, if meets the actual construction, still need to formulate measures, finer steps, this paper only framework reference, deficiency in comment.