

92
J
anuary
2011
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A
rticle
quality and tool life. And the two roll structure is more simple and the
maintenance is more convenient.
Tongze developed the two-roll MPM 140 and MPM180 mill unit, while
mill stand main drive adopted top-drive technology and acquired the
innovation patent:
• The six-stand for MPM consist of three horizontal-rolling
stands and three vertical-rolling stands with horizontal-vertical
interlacing. The top-drive mode is adopted by the vertical-
stand, which protects the vertical main gear box in a better
way. It is very different from the X-mode rolling form of other
manufactures since it takes up less space, is a lower cost and
benefits from fast tool alteration.
• The lateral roller change is adopted by roller to enable the
convenient maintenance and compact structure and so on.
• The combination of 4-roughing stands and 2-finishing
stands ensures the absolute diameter reduction of wall
thickness of up to 12mm, the relative wall thickness
reduction rate close to 70% and the maximum elongation
extend to 4.6mm, which is the largest one among mill units
of the same standard.
• Tongze provides pass-design software to the customer and the
parameter design of each pass stand can be automoatically
achieved by inputting the specification of shell and finished.
The curvilinear equation of metal outline for roller-gap is
constructed through the analysis of the test billet for the metal
outline in the gap-roller area, in accordance to the different
pass-pattern of rough-rolling and finish-rolling stands, which
attain the least outlet deviation of the continuous rolling
pipe.
• The mandrel-design software is provided to the customer, the
mandrel class interval and the most reasonable limit of tolerance
margin for wall thickness of shell billet is divided in consideration
of the different limit of tolerance demand for thin and thick wall
thickness.
New technology introduced for
continuous rolling mill
in Taiyuan Tongze
Chief engineer, Guo Jibao, Taiyuan Tongze Heavy Industry Co Ltd, Taiwan
The application of a hydraulic press down
system in MPM
Compared to mechanical press down technology, hydraulic press
down technology possesses advantages in the area of performance,
precision and response. With the application of hydraulic press
down technology in MPM, it helps reveal whether the MPM has
good integral rigidity and the roll-gap deviation caused by the
stand bounce and bearing clearance can be eliminated through
the dynamic compensation of hydraulic servo system. The roll-dap
dynamic adjustment can also be carried out in the rolling process,
the reducing of wall thickness of tube’s top-and-end can be achieved
by the adjustment of roll-gap and roller rotate speed to reduce the
loss of crop loss by gradual end reduction. The distribution for each
stand load of MPM can be accomplished by the test of rolling force
and adjustment of roll-gap to ensure the rolling stability.
Self-directed development of hydraulic press down system is
equipped in the unit of MPM114 and MPM180, this system includes
the mathematical model of rolling process roll-gap control and the
rolling speed, temperature, wall thickness and rolling force control
strategy.
Six-stands two-roller MPM
For the existing two-roll production state, two-rolls have no differences
compared with three-roll rolling when rolling small size pipe in terms
of the field of accuracy, wall thickness, internal and external surface