JOY采煤机和液压支架新技术

n longwall mining, powerful shear-ing machines drive back and forth across coalfaces of up to 400metres (1300 feet) in length, producing coal at rates of up to one tonne every second. What makes these impressive coal production rates possible are the massive hydraulic roof supports that shoulder the roof until the shearer has completed its pass.

“No other manufacturer in the world has produced as powerful longwall roof supports than has Joy Mining Machinery,” said Clive Hibbert, Product Director - Powered Roof Supports and Armored Face Conveyors.

“Joy has a long history of manufac-turing roof supports and other compo-nents of longwall systems. In 1996, Joy not only became the first single-manu-facturer of complete longwall mining systems with the acquisition of Longwall International, it also acquired Longwall’s expertise in manufacturing roof supports, which goes back to 1950.

Since the acquisition of Longwall International, there never has been a recorded major failure involving JO Y roof supports” Hibbert said. Hibbert credits several factors for Joy’s success.“First is operational experience. JO Y longwall roof supports are involved in more than 60% of the active longwall mining faces currently in operation in Australia and more than half of all those in the United States, and” he added,“complete JOY longwall mining systems comprise more than 70% of the single-manufacturer longwalls operating today.

“Much of this success has to be attributed to our engineering team,” he

continued. “Joy has a large number of degreed engineers worldwide involved in the design and manufacture of long-wall mining equipment.

“These engineers, using advanced analytical tools, consistently produce exceptional designs. They demand the use of high strength steels and incorpo-rate their own-designed advanced hydraulics, which results in the high performance of our supports” Hibbert noted. “Joy requires that each compo-nent in every piece of mining equip-ment meets the highest of standards.For example, every roof support struc-ture manufactured is inspected by Joy personnel to ensure detailed processes in the welding are adhered to for the purpose that high quality and integrity are maintained.

“Finally, when you have designed and manufactured the strongest roof sup-ports, you have to prove the product adds value,” Hibbert said. “As a matter of routine, Joy maintains the most strin-gent structural testing in the industry that is applied to our longwall roof sup-ports. At the companies Wigan, United Kingdom, testing laboratory, Joy has

the capacity to test units up to a rating of 2500 tonne (2755 ton) on roof sup-ports ranging up to 6 metres (20 feet) in height.”

This is the highest rated rig capability in the world today, and Joy put it to use two years ago to validate our design of the world’s most powerful longwall roof support.

Joy had been asked by Australia’s Moranbah North Mine to provide a complete longwall mining solution incorporating the highest capacity longwall roof supports with a never-before-achieved shield yield ratings of at least 1750 tonnes (1930 tons).“Accomplishing this required a ded-icated effort,” Hibbert said. “Where typ-ical shield fatigue testing requirements range between 30,000 and 60,000cycles, the final fatigue checking on the Moranbah shields successfully

achieved 90,000 cycles; something unheard of in the industry, until Joy did it.”

Hibbert added that, because leg life expectancy is designed to exceed that of the major support structures, the legs also were tested successfully for more than 90,000 convergence cycles. Joy also increased the leg diameter from 400 mm (16 inches) to 480 mm (19inches) which, he said, involved innova-tive engineering in the design of the cylinders, seals, bearing materials and feed pipes.

“Additionally,” Hibbert said, “Joy designed into the new roof supports an active compensating ram that stabi-lizes the hinge point between the canopy and the rear of the shield. This was done because Joy engineers had determined that, by both increasing the size of the ram and by activating it at times other than just during shield advance, it enhances the tip loading of the supports during both free standing and yield conditions”.

“The end result of these accomplish-ments,” he continued, “is Joy’s highest rated, highest fatigue life longwall roof support that weighs more than twice that of many of the supports in use today. That same effort, the engineering attention to detail and innovative think-ing, goes into the design and manufac-ture of every JOY longwall roof support.”

“As has been proven again and again,” Hibbert said, “and proven where it counts most, in longwall min-ing applications worldwide, under the most severe and demanding conditions found to date, Joy’s record of accom-plishment, performance and reliability is unmatched.”

JOY Roof Supports, Giants of Longwall Mining

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October 2010oy Mining Machinery manufactured its 200th

7LS model shearer and shipped it to the Shaanxi Coal Group in China. That makes 200 JOY 7LS shearers shipped globally and 90 JOY shearers now in China.The most productive min-ing operations in the world choose the JOY 7LS because it mines at seam heights and production rates never before attained.

Capable of single-pass mining the thickest extrac-tion in excess of 20 feet (six metres), this high-perform-ance shearer incorporates a powerful haulage unit with JNA controls and achieves customer expectations for Zero Harm, Most Productive Equipment and the Lowest Cost Per Ton.

For more information visit

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JOY Ships 200th 7LS Shearer

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The JOY Longwal System

Clive Hibbert

Joy designed and manufactured the world’s highest rated yield load of any

roof support at 1750 tonne (1650 tons) as of March 31, 2010.