Mitsubishi Heavy Industries, Ltd. (MHI) has developed a new "GEA Series"of gear hobbing machines capable of processing large-size workpieces that exceed 1 meter in diameter. Marketing of the GEA1200, the first model in the series, will commence on May 27. Equipped with a highly rigid hob head and rotating table, the GEA1200 can accommodate high-efficiency, high-precision machining of gears up to 1,200 millimeters (mm) in diameter. Going forward MHI will explore a broad range of demand for heavy-duty machining applications, including production of step-up gears and gear reducers used in wind turbines and construction machinery.
The GEA1200 hobbing machine comes equipped with a 30 kilowatt (kW) main motor - a 60 kW option is also available - and a 1,200 mm diameter hydrostatic bearing table capable of bearing superimposed loads up to 15 tons. The large-size hob, with maximum diameter of 350 mm (option: 500 mm), rotates at a speed of 25 - 250 revolutions per minute and cuts gears - up to 20 modules* (option: 30 modules) - on workpieces. The GEA1200 is highly efficient and can reduce machining time by about 30% compared to existing hobbing machines of this size. The machine has secured JIS7 (Japanese Industrial Standards) class machining precision.
The GEA Series is part of MHI's "Mitsubishi E Series" of new-generation gear machines designed for energy saving and high operability to meet global standards with regular specifications (without optional equipment). Machines in the E Series, which includes hobbing, shaping and gear grinding machines, all feature the same concept in order to facilitate the creation of production lines combining these machines. Many energy-saving features are standard, noise reduction and environmental friendliness have been maximized, and operability and maintenance ease have been enhanced.
In developing the GEA Series, MHI's Machine Tool Division collaborated with the company's Technical Headquarters in conducting various rigidity analyses relating to the basic structure of large-size gear cutting machines and measures for thermal displacement. Collaboration enabled the achievement of enhanced machine rigidity, a shorter development period, and improved machining efficiency.
Recently demand for large-size gears has been increasing for applications involving step-up gears and swivel parts in wind turbines, gear reducers and traversing gears used in construction machinery and deck cranes, and various gears used in servo presses, marine machinery and iron and steel manufacturing machinery. At the same time, high-efficiency and high-precision gear cutting machines are being sought globally. Also, for processing gears with diameters smaller than 1,000 mm, demand is increasing for machines capable of heavy-duty machining, which is difficult to perform using conventional hobbing machines. The GEA Series was developed to respond to all of these needs. Going forward MHI plans to develop and introduce models to accommodate even larger workpieces with diameters of 1,600 and 2,000 mm.
Spurred by the market launch of the GEA1200, MHI now looks to introduce gear shaping and gear grinding machines that can accommodate up to 2,000 mm diameter workpieces. At the same time, plans call for the company to establish a new business model encompassing after-sale services, maintenance and tool supply, primarily for large-size gear machines. By offering new values to gear manufacturers, MHI aims to secure stable orders and sales.
*Module is the unit used to indicate gear size. Module = pitch circle diameter divided by number of teeth.
Major Specifications of GEA1200 Gear Hobbing Machine
Maximum workpiece diameter:φ1,200 millimeters (mm)
Maximum modules: 20 (30)
Axial travel: 700 (1,400, 2,000) mm
Radial travel: 950 mm
Maximum hob size (diameter x length):φ350 x 450 (φ500 x 500) mm
Hob shift:350 (400) mm
Hob speed: 25-250 revolutions per minutes (rpm)
Rated output of main motor:30 (60) kW
Floor space (width x depth):6,650 x 5,700 mm
Machine weight:35,500 kilograms