| 摘要 |
<p>PURPOSE:To make a blank pipe mean thickness value of delivery of a sizing mill constant, by applying a thickness control by known motor rotational frequency or speed ratio, by a stretch reducer, to the sizing mill of a Mannesmann plug mill pipe manufacturing method. CONSTITUTION:As for each blank material from a furnace 1, its number and unit weight W are stored in a device 5, and a length actual value LPLM after rolling a blank pipe by a device 2 is inputted to the device 5. Also, length LRM after rolling by a device 3 is inputted and stored in the device 5 in the same way. For instance, when a mean thickness value is shown by weight (unit weight) per unit length, the mean thickness value of delivery of the devices 2, 3 becomes W/LPLM and W/LRM, respectively, and a device 4 is also shown by W/LSM in the same way. When the tube has reached in front of the device 4, a motor rotational frequency ratio is calculated by the expressionI(expression II: a correcting term shown by a deviation against a mean thickness target value of the pipe of delivery of the device 4 which has finished rolling, (h): a parameter, (i): a passing order of pipe of each rolling or device 3, and in case of the latter, the expressionIis used by 2 pieces), and a command is given to the device and is set.</p> |
