TPT May 2012

A rticle

owners of the enterprise are trying to make the roll change and the adjustment unnecessary. Of course, this can only be a dream as roll change and adjustment is a must if the tube mill is to produce tubes of different specifications. The point is, can we get the same result with automatic roll change and automatic adjustment? The answer is yes. AUTO-DNSA mill is just such a unit with such capacity. To understand its functions, we will need to start with the DNSA mill. DNSA was developed and launched to the market by FD Machinery in 2009. DNSA stands for Digital Non-strip Set Adjust, which means all rolls are located digitally and the unit is set and adjusted under the non-strip status. In other words, the operation no longer relies on experience, and the commissioning will not have any scrap. So far two DNSA production lines are in operation and several others are being manufactured by FD Machinery. It can be seen from the photos below that the locations of all the rolls of DNSA mill have been fixed precisely and displayed digitally. Those figures are not selected by the operation freely. Instead, they are determined by the mill adjustment cards. What the operator needs to do is only to adjust the rolls as per the data on the cards to have the finished products manufactured.

sleeves and rolls shall be pulled out from the side. The process for roll loading shall be in the opposite order. The simple side roll change unit is a drawing machine driven manually, electrically or hydraulically, which is used to pull and push the mill housing. The pulled out mill housing will be lifted by the crane before the rolls are changed. The vehicular side roll change unit is equipped with a roll change cart with the drawing machine installed on top. The cart is installed on the base of the mill via the straight guide rail. The mill housing is pulled to the roll change cart by the drawing machine and the cart carrying the mill housing is pushed away manually prior to roll change. This is a convenient and practical roll change unit. Both DNSA mill and AUTO-DNSA mill are of the side roll change type. Rapid roll change mills with top roll change or side shaft change are common in the early designs. To achieve rapid roll change, the stand of those two kinds of mills should have one or several sets of standby shaft units. The rolls shall be installed on the shaft in advance. When rolls change, one standby shaft unit will be installed to replace the one set in the mill. The removed shaft unit will be changed roll in offline. For both top roll change and side shaft change, the horizontal roll shaft and the drive shaft must

It can also be found from those photos that all rolls have rapid roll change function so that one worker can easily replace all the rolls in one hour without removing even one bolt. For the needs of digitalisation, the requirements on the manufacturing precision and equipment rigidity by DNSA mills are higher than the normal mill in addition to the special design for some structures. FD Machinery spent a whole year to complete the design and manufacture for the first DNSA mill, and has recieved many invention patents for the mill. As mentioned above, easy roll change in short time, roll change and adjustment in DNSA mill are all important performance factors of the mill. The features of various roll change types have been summarised as follows to facilitate a clear understanding of roll change. People have been studying rapid roll change for a long time. For the horizontal roll, there are generally five types of rapid roll change mills, which are respectively side roll change, top roll change, side shaft change, base plate change, and base change. For rapid roll change mills with side roll change, since drive shafts do not need to be removed, no standby equipment or spare parts need to be added, and no secondary roll change is needed. These kind of rapid roll change mills are extensively used in the mills of small and medium size. To change roll for the rapid roll change mills with side roll change, the mill housing at the operation side shall be pulled open, then the

DNSA mill: Squeezing roll

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M ay 2012