Research On Dry Milling Technique Of Spiral Bevel Gear With Spherical Involute

Spiral bevel gear is the basis component of mechanical transmission, can transmit themovement and the power of the intersection axis, with the advantages of strong load carryingcapacity, high transmission efficiency, good stability, low noise, small vibration and so on. It iswidely used in aircrafts, automobiles, engineering machinery and other power machines. Thespiral bevel gear with the ideal spherical involute can be interchanged theoretically and has theadvantages of large contact area, stable instantaneous transmission ratio and so on. It is difficultthat spiral bevel gear with spherical involute is manufactured by traditional method. So peoplehave no choices to adopt approximate method of engineering. Such the tooth profile of the spiralbevel gear manufactured by this method is not the spherical involute due to the error in themanufacturing principle. As a result, the tooth surface can not mesh correctly and many problemsare arosed, such as bad contact area, expanding noise, intensity declining and so on. For correctingthe error, the complex request and the harsh conditions are put forward on the design, theprocessing, the testing, the machine tools of cutting gear,etc.In order to solve the above problems, this dissertation uses a new surface forming methodwhich is called method of generating line. The content of this method is that the tooth surface ofspiral bevel gear is formated by a straight line or a curve on the tangent plane of great circle whichmake pure rolling on the base cone. The generating line is treated as cutting edge, the tooth surfaceof spiral bevel gear is cutting by the knife-edge which make pure rolling on the base cone. Theideal gear surface with spherical involute is able to obtain and the machine tools, cutting tool andmovement are simple by the method of generating line. Based on the theory, this paper putsforward a new method of dry milling of spiral bevel gear. So it can greatly reduce pollution andlower the processing cost. The main content of this dissertation includes surface forming principle,dry milling processing technology, gear dry milling simulation and gear milling experiment.（1）Firstly, the dissertation deeply analyzed the formation of the spherical involute profileand conical spiral involute surface and further researched the method of generating line and themovement relationship of tooth surface generation process. Combined with dry milling technology,Tool technology, machine tool technology and process technology of dry milling required were analyzed. In accordance with dry milling technology requirements, the machine tool and thecutting tool were designed and the reasonable technological parameters were chose.（2）Finite element simulation of dry milling of spiral bevel gear with spherical involute hasbeen implemented by the finite element software Deform-3D. First established the simplifiedmodel of milling cutter and gear blank using CATIA software. Then added the required movementof milling cutter and gear blank, chose the reasonable boundary condition and carried on thethermal-mechanical coupling simulation of milling gear. Finally, according to the simulationresults, stress, strain, milling force and milling temperature of the milling process were analyzed.（3）The installment and the debugging of machine tool and NC machining simulation ofgear milling process have been implemented. First designed a pair of conjugate bevel gear,calculated the tool track spots according to the motion equation and wrote NC machining programusing these track spots. Then created3D model of machine tool, milling tool, fixture and gearblank, selected appropriate control system, import NC program and carried on the simulation ofgear milling process by CNC machining simulation software VERICUT. Finally, according to thesimulation results, the correctness of the motion equation and NC program was verified.（4）Dry milling experiment of spiral bevel gear was carried out. A pair of conjugate bevelgears of which modulus is6and number of the tooth is respectively65and14were machined. Inaddition, the large gear is left rotating and the pinion is right rotating. According to the experimentresults, the correctness of the method of generating line and the simulations was verified.