The cracks were found on Stellite6 alloy block part after the structure put into use a period. After analysis the cause of cracks is the welded structure of Stellite6 alloy block and sink roll bush body. In the production the line is under high temperature environment of greater than 600 ℃.The state returns to normal temperature after the offline. In this process of expansion and contraction, Since Stellite6 alloy material is different with bush body material 00Cr17Ni14Mo2, the thermal expansion coefficient is different, so that Stellite6 alloy subjected to tension and pressing force, thus cracks even breaks were found at weld position. See figure2.
Figure 2 sink roller bush after use offline
From whole assembly drawings (Figure 3) The clearance between carbide block and sink roll sleeve end is 13 mm, while the spacing between sink roll head and stopper block is 15mm. That means actually the head did not play the effect of reducing friction area.
2. Improved sleeve
In order to avoid recurrence of the above two cases, the bush re- designed and the assembly form changed. See figure4 Improved bush structure
a. Due to the action in the course of the strip steel, the actual contact surface of the roll sleeve and the bush is in the upper part of the bush. Therefore, the Sellite6 alloy blocks changes to one unit which can still meet the requirements and also reduces the manufacturing cost.
b. As for Sellite6 alloy part (part 2) installation, two stoppers (part 3) welded at two sides and 2 semicircle with material 00Cr17Ni14Mo2 (part 4) welded at the lower half of the body to support. Not to weld Sellite6 alloy directly with 00Cr17Ni14Mo2 body which reduce the difficulty of construction and potentially dangerous.