TPT January 2011

anuary

2011

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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