Research On The Abrasive Belt Grinding And Polishing Tool System For Blisk Finishing

Aero-engine technology is an important manifestation of comprehensive strengthfor the aviation and equipment manufacturing industry nation. An evaluation of aero-engine’s performance is the thrust-weight ratio. Blisk (blade integrated disk) is thecore part of aero-engine which could increase the thrust-weight ratio. Fan, compressorand turbine of high efficient aero-engine are mostly designed to be the blisk. Thoughthe use of blisk can decrease number of parts and weight of aero-engine, its complexfree curved surfaces and narrow channels between blades make it more difficult to bemanufactured. It is a supreme goal for all engineers to improve blisk’s accuracy andsurface roughness.There are several methods to manufacture the blisk, milling is more widely used.However，there remains lots of tool marks after milling operation which will damagethe dynamic performance of aero-engine that need to be polished. Automatic grindingand polishing technology for blisk abroad is more advanced than in the domestic.Manual polishing methods are still widely used which have many disadvantages suchas low efficiency, bad quality and poor consistency. Yet we don’t have enoughautomatic grinding and polishing machines either. These, however, make seriousimpact on the technical promotion of aero-engine industry. Abrasive belt grinding andpolishing is a fine method with good quality, high efficiency, more practicality andeconomy. It is widely used in grinding and polishing separate structure blades.Considering the potential risk of interferences between belts and blades, it is barelyused for blisk. Therefore, it is necessary for us to develop a new type abrasive belttool system for open blisk grinding and polishing.The dissertation has identified the five basic movement freedoms of tool systemby analyzing open blisk structure and characters of gantry machine tool and horizontalmachine tool. Proposed four schemes of tool system, one is a flexible tool system witha grinding wheel as tool head, piezoelectric ceramic transducers (PZT) and flexiblehinges as polishing force controlling devices; the other ones are all abrasive belt toolsystems with different combinations of contact patterns according to an idea that itwill be better to use different contact wheels to polish the opposite two sides of a blade separately. Briefly introduced the grinding and polishing mechanism andprocess of abrasive belt, decided several essential process parameters.Based on the principle that use different contact wheels with different belt wrapangles to polish the opposite sides of a blade separately, the dissertation has developeda new type abrasive belt grinding and polishing tool system. The dimension and wayof installation of the tool system have been determined. All the structure designs andselection calculations of grinding and polishing device, driving device, belt tensioningdevice, polishing force controlling device have been accomplished. The condition ofspace movement of the tool system when it is operating has been introduced. All partsin the tool system have been modeled, virtual assembled and interference inspected byusing3D modeling software. The static and vibration modal characteristics have beenstudied by using finite element analysis (FEA) software. Generally speaking, this toolsystem has many advantages such as simple structure, economy and practicality, easyto be generalized.The biggest problem for the abrasive belt tool system to grind and polish blisk isthat the belt maybe interfered by the blade nearby. The belt wrap angle of the contactwheel is the most critical influence factor for the interference trouble. The wrap angleof the tool system in this subject was designed by tentative drawing again and again.It is merely compliant for this open blisk model, not suitable for others. Therefore, thedissertation has studied a calculation method to estimate the optimal range of contactwheel belt wrap angle which will avoid or reduce the interference cases between beltand blisk. The biggest advantage of this method is that, it only needs some coordinatepoints in one single blade, not all blades or even the blisk object itself. By usingknowledge of coordinate transformation, curve fitting and numerical calculation, thismethod can give support to tool system design, make vital contribution to expand theapplication of abrasive belt in the open blisk grinding and polishing field.