In bar rolling process, the technical conditions of roughing may change and make camber occurred, for example, different temperature at both bar side, bar wedge and off-center in biting.
The results show that: 1 the destruction develops first from the center line of both sidewalls of roadway, after the local failure, there gradually formed a pair of "wedge" failure zone.
试验结果表明：1破坏首先发育在巷道两帮中线，局部破坏产生后，逐渐形成一对“楔形”破坏区域。
3
Lock adjusting mechanism of two connecting rods and two optical wedge lock nuts of sighting telescope center (No. 7 in Fig. 1).