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What are the key points of hollow shaft crack treatment in tube mill

Date:2019-10-12 11:12     writer:cement editor     Views:

The cracks of hollow shaft mostly occur in R region, because the defects are easy to occur in casting and knife lines are often left in machining.At the same time, the site of alternating stress is large, easy to fatigue, fatigue crack.What are the key points for crack treatment of hollow shaft in tube mill?

1. After crack is found, the machine must be shut down as soon as possible to avoid crack expansion or accident expansion.


Hollow shaft of tube mill
 

2. After shutdown, check the specific location, length and depth of the crack, and analyze and determine the cause of the crack.Make maintenance plan.

3. Test the end face and radial runout of the hollow shaft, and judge whether it is beyond the standard range according to the standard.If the crack depth is relatively shallow, such as less than one third of the thickness, the length within one meter, can be directly cut off the crack welding treatment.

4. Slow tube mill, test and record the radial runout of the hollow shaft.


Hollow shaft of tube mill
 

5. First, transfer the welding position to the convenient position of the tube mill and clean up the welding position.Use air plane to rise from crackle middle first, crack plane is opened, dig to do not have crackle so far, want to plane to base material thickness to crack thoroughly 2/3, planer opens length 100 millimeter or so, if crackle length is longer, can every lie between 500 millimeter plane is opened, but need planer one paragraph, weld one paragraph, prevent crack to expand.

6. For the gouged part, it is necessary to polish the gouging mouth until the metal luster leaks, and then carry out welding. During the welding, pay attention to each welding layer.

7. The above intermittent welding, one is to prevent the crack expansion, two is to prepare for the next step of fully gouged welding seam, three is to prevent a large area of welding produced shrinkage, affecting the jump of the hollow shaft.

8. After the intermittent welding is completed, first slowly turn the tube grinder to check the radial runout of the hollow shaft.The runout of the hollow shaft should be checked in the middle of the welding. If there is no problem, the welding can be continued until the welding is full.


tube mill
 

9. After welding the internal cracks in the tube mill, make the sample and polish it to reach the required accuracy.

10. After the inner weld is finished, the radial runout of the hollow shaft shall be detected. If there is no problem, the outer side of the crack shall be gouged, and the welding shall be welded in turn to reach the full welding, and the grinding weld shall reach the accuracy requirement.

11. Finish polishing all the inner and outer welds of the tube mill. Check the run-out of the hollow shaft diameter to ensure that it is less than three times of the standard.

At last, the weld was tested to meet the requirement of ultrasonic secondary.

12. Other instructions :(1) if the hollow shaft in the middle of the welding is too large, the welding should be stopped and the opposite welding should be carried out to achieve the purpose of anti-deformation.(2) during welding, shall be continuous, to ensure the temperature between welding layers, and to take wind protection measures, and to carry out appropriate cotton insulation, to prevent sharp contraction, crack.

This article is only for the hollow shaft crack key point explanation and remind, if the actual construction, also need to develop perfect measures, more detailed method steps, if you have any questions can contact us online customer service.

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