Titanium tube end rolling defects cause analysis
Time: 2013-08-01 11:55
Titanium seamless tubes in chemical, aerospace and other industries have a more widely used. Titanium seamless pipe rolling commonly used reciprocating (ie Pierre format) cold rolling mill for processing, pipe in the deformation process as well as a rotary mill feed, gradual reduction wall, reducing per unit length of the pipe in a rolling pass is generally 5 to 10 times after rolling, finishing process requirements in order to obtain pipe sizes.
Seamless pipes commonly used titanium cold two rollers (LG) and a multi-roller (LD) for multi-pass rolling mill. LG mill can be greatly reduced diameter, reducing wall processing, but the lower dimensional accuracy after rolling, tube ends prone to cracking, uneven heartbeat and other phenomena, for the cracking phenomenon, primarily through the tube before processing grinding, flush, etc. ways to solve; pipe ends for missing appears, similar to the "fish mouth"-like phenomenon, in the subsequent processing of the need for flat-head handle, otherwise it will cause the plug stuffy car accident, therefore, researchers from the process, tooling, equipment, etc. aspects of analysis, aimed at identifying causes raggedness reason the pipe end, to take effective measures to resolve.
Select 10 GR2 titanium tube as the research object, tube specification Φ80mm × 5mm, cogging selection LG60 two-roll mill rolling after rolling pipe specifications for Φ66mm × 2.5mm, before rolling the pipe end and marked , measured with a micrometer diameter, wall thickness, the area measured again after rolling diameter and wall thickness, and observe the site after rolling in the recesses or protrusions.
Through process analysis, tooling analysis, were not found to cause defects in the real reasons, the final device analysis.
Caused by the device does not have a wall thickness of the feed amount, the rotation angle of movement coordination and other reasons. Rolling speed and the amount of feed in accordance with the requirements of the implementation process, the equipment is running, turn the rear dead point and sent the former dead rotation, motor coordination and found no rotary conveying action in advance and lag phenomenon; observed rotation angle is 52 ° ~ 53 °, in equipment design requirements within the scope of; continue to measure the amount of feed during rolling and found the amount of feed evenly, but found that the feeding tube when the tube coaxial with the core rod ran around larger, reaching a 10mm, the core rod as required before and after the rolling runout should not be more than 0.5mm, the rolling otherwise it will seriously affect the accuracy of the location when the mandrel, the mandrel further examination revealed trolley connected to the core rod spline clearance at 20mm, 8mm beyond the requirements of the gap. When the feed pipe in the rear dead point, since the spline mandrel gap is too large, will inevitably lead to the plunger tube also advances forward, so that the core rod rolling mandrel connected to the position of a relatively Large changes, namely: the position of the mandrel and the hole is no longer process the set position, but forward. So that when rolling to the front dead center, the pipe is actually rolled into thinner dimensions; But while the core rod in tube walked along the spline end of the spring has been the force at this time, when the pass went front dead center, the pipe bore disengaged from the mandrel, then the spring will push the plunger, so that the mandrel is back, then pass the side of the pipe wall thickness after rolling the thicker parts of the reeling , but due to the retreat mandrel, the average thickness of the thicker part of the whole has not been reeling, thus creating a large differences in thickness. Adjusting the core rod and the core rod clearance trolley spline connection, by adjusting, found missing tube end disappears.
Therefore, the core rod and the core rod trolley spline connection gap is too large and the resulting position of the mandrel the tube is caused by a serious shift pipe ends after rolling the main raggedness