Manufacturing Technology Of Skew Bevel Gear With Spherical Involute Based On Tracing Line Method

Spiral bevel gears are the key components for transmitting speed and power betweenninterseeting axes and they are widely used in fields of aviation and space, ships, nationaldefense equipment, automotive vehicle and kinds of machines such as machine tools,engineering machine because of the advantages of large coincidence degree, steadytransmission and high strength. However, manufacturing technology of spiral bevel gearsbecomes a research hotspot in both domestic and overseas due to the complexity of thedesign process the difficulties in machining.The tooth profile of spherical involute is ideal profile of spiral bevel gear. In the cuttingprocess of spiral bevel gear, the machining method is the method of engineeringapproximation about gleason system spiral bevel gears that are widely used at home andabroad. Tooth profile design is always in-plane, but different from cylindrical surface and thecone surface, spherical surface can’t spread in-plane. So the tooth profile of bevel gear isapproximated by the profile of equivalent cylindrical gear which is unwrapped on the backcone. That the principium error which will be producted may lead to incorrect mesh and badcontact of gear surface. And process and assemble of a pair of mesh gear must be carried outin pairs. But the above method need be modified repeatedly. Although gleason gear has beenstudied more than one century. Up to now, many scholars take on the research of this field,and they have achieved many good results. However the question of theory error still couldnot be got rid of and complex design and manufacture can result in low efficiency, longperiod and high cost. In addition, gleason keep technological monopoly all along and thecore technology can not be shared to the external world.In the gleason system, toothed portion of spiral bevel gears is designed as a circular-arcin order to make cutter head cut continuous rotary. therefore, circular-arc bevel gear has beenthe pronoun of spiral bevel gears. One of spiral bevel gears-skew bevel gears have alladvantage of spiral bevel gear such as large coincidence degree, steady transmission andhigh strength. Up to now, high precision processing method of skew bevel gears has not beendeveloped and processing theory and technology of skew bevel gears are not enough mature.Based on the research practice of my group, new processing method-tracing line wasput forward to breach the current theoretical and this method can realize tooth machining atthe same time can obtain spiral bevel gears without principle errors. In this paper, study isimplemented on design and machining of skew bevel gears and manufacturing technologysystem will be established. The main research works in this dissertation are as follows. The generating principle of tooth surface was analyzed. Basic cone and basic planewere constructed. The tooth surface of spiral bevel gear with spherical involute was formedby the arc generating-line’s pure rolling on the base cone both sides tooth surface aregenerated by adjusting generating-line parameter and rolling direction.The relation of geometrical parameters between base cone and pitch cone were studied.Traditional design, machining and meshing are based on pitch cone. However, the newmachining method is related with base cone. In this paper, parameters equation of base coneand pitch cone are established and key geometry formula are deduced. Theoreticalfoundation are provided for design of gear surface, machine, cutting tool, process by theparameters equation.New method of gear surface was put forward based on two parameter which are polarradius and base cone corner. Mathematic model of left and right gears surface were setup. And meshing formula of spiral bevel gears was deduced. At the same time, consistencyof generating-line and meshing line were demonstrated.Mathematical model of gear surface about skew bevel gears was set up according totracing line. Based on generating theory of spiral bevel gears, gear surface of skew bevelgears are formed throught relative motion between gear blank and cutting which is used asedge generating line of base plane. And motion equation was set up finally.Three axes linkage method of cutting gear surface is put forward that gear groove areprocessed by finger milling cutter and finish machining of gear surface is carried out by discmilling tool. Head face edge of disc milling tool and base plane vertical intersect at thegenerating line. And the relative motion between gear blank and cutting follows thegenerating theory of gear surface. Finally, finish machining of gear surface was realized bythree axes linkage,and motion equation of finish machining was set up.Second,outer cornerformula was established. Based on finish machining project, processing of gear groove isaccomplished through finger milling cutter feed along spiral line of conical surface which isobtained by adjusting cutting section corner. And motion equation of gear groove was set up.The movement simulation and of NC machine working was carried out. Processing ofgear groove and finish machining of gear surface were accomplish accomplished.based onthe simulation, structure of machine and cutter were designed.Research of rremble was developed about disc milling tool and finger milling cutter inorder to determinate cutting parameters with new processing method. Analytical model offlutter instability is established and experimental modal parameter identification was carriedout. the figure of spindle speed and radial cutting depth were rendered about two cutters. Assembly technology clamp was designed and machined on the basis of a couple ofgears parameter and practical manufacture was carried. Gear profile of gear was measuredthe results showed that: gear surface normal error between-7.7μm-11.7μm, the performanceof this method is verified by experimental results.