The most common defects for seamless steel pipe is uneven wall thickness. For example carbon steel pipe, thickness deviation from the capillary puncher at least 7.5%, reducing the elongation rolling to 4.5% increase to 7% after expanding, then after tension reducing to 4.5%.
Seamless steel pipe wall thickness deviation performance reasons:
Since puncher in the head with a perforated plunger between the first support frame centering rollers cantilever structure is formed, so that the head during piercing irregular beating, so the head will be uneven force within the tube, causing the wall thickness deviation.
Manufacturing precision equipment and structures
Since the stability of the perforator roll and the guide plate is poor, so that the device generates a large jump in the perforation, the impact of the tube thickness of the device manufacturer; old structure and centering rollers on the roller and is generally due to the lower roller is not an institution drive, so the centering rollers, its center at the time of the actual installation and adjustment, the theory is not easy to pinpoint the center generated when the plunger hold three centering rollers, so that will result in the perforated top radial centering rollers hold the rod being produced uneven stress, poor stability, causing the wall to produce deviations.
Tube heating process
Heating tube is very important, if uneven heating the heating tube, and will produce yin surface discontinuity such that the perforator is offset occurs plug during piercing, resulting in the low temperature side capillary wall thickness of the thin wall high temperature .
Cutting the tube
Quality tube cutting rates will also have a significant impact on the pipe wall thickness deviation, because the use of shears cutting knife edge quality is not high, sings like a horse section generated more serious moments of piercing machine head bite Slide into the produce section, as well as causing eccentric produce thickness deviation.