STRAIGHTENING METHOD AND STRAIGHTENING MACHINE OF METALLIC PIPE

摘要

PURPOSE:To control constantly over the whole length the crush quantity given to a metallic pipe by performing the rolling reduction with low and high liquid pressure respectively of the pipe end part and pipe medium part in straightening the bend of a metallic pipe through the space between the roll couple with a liquid pressure rolling reduction device. CONSTITUTION:A control device 40 changes a solenoid valve 13 to an oil feed stop, a solenoid valve 18 to a stop oil feed, when the pipe tip is detected by an optical sensor 42 after a pipe P being transferred. The pressure of the oil chamber 11a of the single motion cylinder 11 concerning a roll 1 is thus changed over gradually to low high and the roll 1 increases the crushing power gradually after its biting the pipe tip with a low pressure and starts to crush the pipe medium part. The pipe P therefore has the crush quantity of the same extent over from the tip to the medium part. It is same in rolls 2, 3. And when the pipe rear end is detected by an optical sensor 41, it changes the valve 13 almost simultaneously to a stop oil feed and the valve 18 in an oil feed reflux stop and by decreasing gradually the crushing power of the roll 1 the crush quantity of the same extent is made over the whole length of the pipe P. It is same in rolls 2, 3.