數(shù)控機(jī)床畢業(yè)設(shè)計(jì)外文翻譯---對(duì)電控帶式銑床運(yùn)用液壓自動(dòng)精度控制和寬度控制-數(shù)控設(shè)計(jì)(已修改)
2025-06-01 01:22 本頁(yè)面
【正文】 大學(xué)畢業(yè)設(shè)計(jì) — 外文翻譯 1 ? Appication of hydraulic AGC and width control to a hot strip mill Davies,Project Sale Manager,Engineering and Construction Div. Davy Mckee (Sheffie id)Lid, Sheffieid, U. K. THE Pohang Iron amp。 Steel Co.(POSCO) hot strip mill at Pohang, South Korea,is a modern, threequarter continuous mill built by Mitsubishi in mill is 2050mm wide,has four roughing stands and seven finishing seven finishing srands have a bined power of 56,000kw with a maximum strip speed of 21 metres/ weight is up to tonnes. Annual mil capacity is million tonnes. To improve width and gage tolerances,POSCO decided to install hydraulic automatic width contol (HAWC) on the last edger (E4) and hydraulic automatic gage control (HAGC) on finishing stands F4 to F7. Davy McKee39。s contract was for the total ackage associated with modernization of the mechanical and hydraulic systems,the puterbassd AWC/AGC controls, new widthmeter, mechanical installation, missioning and training. The new equipment was put into service during a 14day shutdown in 1987. ? Outline of new facilities A priority requirement was that the new equipment should be integrated with the existing facility in such a way as to permit reversion to conventional operation in a few seconds. Accordingly, hydraulic AGC and AWC cylinders were designed to withstand normal rolling conditions when in a collapsed state. All of the control systems had to be in parallel with the existing systems (which were retained ) and existing operator39。s desk contromechanical system, depending on which system was selected. The AWC system prises shortstroke, singleacting cylinders (four in total )engineered between the ends of the horizontal screwa and the vertical roll chocks . These cylinders are servocontrolled, with a stroke speed of 100 mm/s (4 ips) to provide in bar width control. (With the bar being typically 50 mm thick at this stage, only a limited 大學(xué)畢業(yè)設(shè)計(jì) — 外文翻譯 2 amount of correction was expected.) A new widthmeter after roughing stand R3 is used to give feed forward control signals to the edger E4 AWC with the existing widthmeter after rougher R4 providing bar to bar updating . The AGC system on the last four finishing stands has shortstroke, singleacting cylinders located between the top chocks and the acrewdown thrust bearing/load cell cylinders have excetionally high dynamic performance (28 Hz ,10 mm/s velocity ). Becayse of the physlcal distance between the edger E4 and the finishing stands F4 to F7 ,separate pump sets serve each atra ,The hydraulic pressure is 275 bars, mineral oil,with a filtration level of 3 microns . The new puter configuration pries a work of seven PDP 11/73 microprocessors linked by an Ether highway . An unusual feature of the system was the need to tap into the existing 64way parallel munications link between the existing supervisory control puter (SCC) and the melplac plc39。s which perform the screwdown AGC, The tap had to be transparent to existing munication and of a high integrity . (Hence a warm spare stand by puter was included in the system .) The required data for the AGC/AWC was extracted , serialized and municated to the new system along the Ether , highway , This had the advantage of opening up the puter system to easier munications in the future , as new systems could be attached easily to the Ether .(A few months later , a further contract for ENCO heat retention panels and interstand water curtains was retention panels and interstand water curtains was received which required a further 11/73 miceoprocessor .) ? Mechanical/hydraulic design features AGC cylinders Various ponents of the AGC cylinders and their assembly are illustrated in Fig . 4,5 and 6. The cylinder design incorporates a single , low friction seal that constests of a Teflon band mounted on the piston below a bronze , side trust ring . The base of the piston is chamfered to give a rocking surface when the cylinder is used in a collapsed state .It gives the necessary degree of freedom to absorb the normal deflections in the mill . 大學(xué)畢業(yè)設(shè)計(jì) — 外文翻譯 3 A hydraulic manifold is mounted to the front of each cylinder that includes the of the position transducers is slightly discernible behind the small accumulator .Another position transducer is fitted diametrically opposite . The two signals from the transducers are averaged to provide a mean stroke signal . The transducer package is shown in .The Sonymagnescale transducers with 1 micron resolution are hermetically sealed insode the brass bodies . Threestage servovalves are employed (Moog 79 series ) .The third stage has its own builtin closedloop position control . Each valve is nominally rated at 230 litres /min . Two valves
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