Original Title: Rolling Methods and Precautions for Titanium Seamless Tubes-Yucheng Titanium Metal The rolling of titanium seamless tubes is generally carried out by reciprocating (i.e. Pierre type) cold rolling mill, and the multi-pass rolling is generally carried out by twin-roll (LG) and multi-roll (LD) rolling mills. During the deformation process, the wall thickness and diameter of the titanium tube are gradually reduced with the rotation and feed of the rolling mill. The pipe with unit length can be rolled for 5 to 10 times in one rolling pass to obtain the pipe size specification required by the process. Cold rolling mill can greatly reduce the diameter and wall thickness, but after rolling, the dimensional accuracy is low, and the end of the pipe is easy to crack and uneven. Cracking can be mainly solved by polishing the tube blank before processing; for the irregular tube end similar to the "fish mouth" phenomenon, it needs to be flattened in the subsequent processing process, otherwise it will cause stuffy blockage of the plug. Therefore, this article from the process, tooling, equipment and other aspects of the analysis. O as to find out the causes of the unevenness of the pipe end and take effective measures to solve the problem. The main reason for the uneven end of the tube blank after rolling is that the spline clearance at the joint between the mandrel and the mandrel carriage is too large and the position of the mandrel is seriously displaced. The cogging and rolling of pure titanium tubes usually need to be completed many times at a time. After rolling into the required titanium pipe specification, the end of the pipe generally has a small fluctuation of 1 ~ 2 mm. There is no difference in raw material and process between this batch of titanium pipes and the pipes produced before, but there is a serious concave-convex fluctuation phenomenon. The length is 70 mm, accounting for 1% of the pipe length. According to the test results of outer diameter and wall thickness before and after processing, the wall thickness of the sample fluctuates greatly. The average wall thickness measured at the convex part is 2.33 mm, and the average wall thickness measured at the concave part is 2.60 mm, with a difference of 0.27 mm. However, the wall thickness deviation of the titanium tube end after normal rolling is 0.05-0.10 mm, which will inevitably lead to the difference in elongation. It can be said that the unevenness of wall thickness reduction in the rolling process of the end tube is the direct cause of the unevenness of the tube end. Therefore, the unevenness of the pipe end may be caused by equipment or tools. The uneven wall thickness caused by tools and dies has many factors, such as rack and pinion installation, die alignment, die opening, etc. After the measurement, titanium seamless tube , the difference between the opening degrees of the upper die and the lower die was 0.05. The clearance of the hole pattern measured by the feeler gauge is 0.05 mm, and the clearance between the gear and the rack is about 1.6 mm; the rack is fixed on the rack without loosening, and the positioning block is not deformed; the hole pattern is cut from left to right by 0.2 mm, with the zero line aligned. The above measurement data show that the die installation meets the design requirements. Uneven wall thickness caused by feeding speed, rotation angle, action coordination and other equipment reasons. Rolling speed and feeding speed shall be in accordance with the process requirements. When the equipment is running, it rotates and feeds at the rear dead center and rotates at the front dead center, and the action is coordinated, and no advance or delay of the rotary feed action is found. Within the design requirements of the equipment; the feed rate during rolling was measured continuously and it was found that the feed rate was uniform, but the mandrel rod coaxial with the tube blank was found to move by 10 mm during feeding. According to the requirements, the forward and backward movement of the mandrel during rolling should not be more than 0.5 mm, otherwise the accuracy of the mandrel position during rolling will be seriously affected. Upon further inspection, it was found that the spline clearance at the connection between the mandrel and the mandrel trolley was 20 mm, exceeding the requirement of 8 mm. Titanium tube feeding at rear dead center If the clearance between the spline and the mandrel is too large, the mandrel will move forward when the titanium tube blank moves forward, so the position of the mandrel connected with the mandrel changes greatly during rolling, that is, the position of the mandrel and the pass is no longer the position set by the process, but moves forward. In this way, when rolling to the front dead center, the tube is actually rolled to a finer size; however, although the mandrel moves forward with the tube blank, the spring at the front end of the spline is always stressed at this time. When the hole pattern reaches the front dead center, the inner hole of the tube is separated from the core rod, and then the spring pushes the core rod backward, so that the core rod also retreats. At this time, the thick portion of the side wall of the grooved smooth titanium tube is rolled,ti6al4v eli, but the thick portion of the smooth wall is not smoothed due to the retreat of the mandrel, resulting in a large difference in wall thickness. Adjust the spline clearance at the connection between the mandrel and the mandrel trolley. After adjustment, it is found that the irregularity of the pipe end disappears. Return to Sohu to see more Responsible Editor:. yunchtitanium.com