In the process of using 10.9 Plain Hex Bolts during construction, bolt breakage often occurs. It is usually the practice of the maintenance worker to use pliers to clamp outward from the bolt break in the opposite direction of the bolt screwing or to remove the bolt with a wrench using a broken bolt extractor. Although these methods can take out the broken bolts, due to the unevenness of the bolt section and the inability to control the uniformity of the torque during operation, the threads of the bolt holes are damaged, and the newly assembled bolts are not tightly fitted and loosened, resulting in the bolts being broken again.
Therefore, in the operation practice, we have obtained a reliable method of taking out the broken A 307 Hex Bolts without causing deformation of the bolt hole thread.
First make a square iron, the square iron is made by: according to the diameter of the hole drilled on the broken bolt, calculate the size of the square iron; the formula is α = R √ 2, and then take a section of round steel (according to the actual The size of the broken bolt is smaller than the broken bolt. The inner hole is drilled in the drill bed (the diameter of the inner hole is smaller than the broken bolt), and a sleeve is made. When taking the bolt, place the sleeve in the broken position of the bolt. In order to facilitate the operation, the clamp is clamped by hand, and then the drill with a smaller diameter than the sleeve is used, and the drilled hole is drilled by the hand drill. This method of drilling is to make the drilled hole not skewed, without hurting the thread of the bolt hole, and can even control the torque to unscrew the broken bolt). After drilling the hole, use the square iron that was first made into the hole, and then reversely screw it (with a tool plier) to smoothly remove the broken bolt without damaging the thread.