TPT May 2012

A rticle

The rolls are installed in the stands in advance. To change rolls, both the base and the stands are replaced, and the drive shaft connects automatically. In terms of online roll change, this kind of mill is also counted as the automatic roll change. But the removed stands need to have secondary roll change. This kind of equipment was made by Abbey Etna. The mill without roll change is also what people have been pursuing for many years. Mills without roll change for round tubes are limited in break down section. Many rolls outside this area need to be changed. Small and medium-sized tube welded mills have higher precision, better quality products, wider size ranges, more specifications with low equipment and maintenance costs.

Vehicular side roll change unit of DNSA mill

DNSA mill: Turks head

be separate. This is troublesome although this operation can be simplified via some special designs. Moreover, to have a smooth shaft change, the clearance between the slide block and the stand

must be increased, which affects the system precision and rigidity. These two roll change types are used mainly for the design of large mills, for the rolls of large mills are heavier and the shafts are longer, so the shaft change may be easier than roll change. Base plate change is also a common rapid roll change unit. There are at least one set of standby base plate containing all stands to achieve rapid roll change. To lessen deformation, usually two to three horizontal roll stands and several vertical roll stands are installed on one base plate. The stand is installed with rolls beforehand. When rolls are changed, the stand and the base plate will be replaced together. The replaced stand shall have a secondary roll change. OTO Mill and FD Machinery are manufacturers of two different base plate change mills. The drive shaft of OTO Mill is installed on the base plate and FD Machinery has three mill housings for each horizontal stand. The one near the drive side separates and connects the horizontal shaft and the drive shaft automatically via movement forward and backward, which is not changed together with the base plate. There are few rapid roll change mills with base change available, which has at least one set of standby base installed with all stands. Usually there are two bases, namely, the forming base and the sizing base.

DNSA mill: Guide roll and impeder

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M ay 2012