Several Technical Problems Of “Four-cutter” Method For Spiral Bevel Gears

The design and manufacture of spiral bevel gear occupies a very importantposition in the machinery industry. Currently "five cutter "method is still widely usedin the spiral bevel gear processing which requires more equipment, occupies a largeplace and the backlash is bad; while the abroad "two cutter " method has been widelyused that have not been promoted for some basis technical restriction in our country.In this context proposed a "four-cutter" processing theory that the rough cut and finishcut of pinion, rough cut and finish cut of gear are double method.In this paper the structure of spiral bevel gears is researched, the calculation ofgeometric parameters and machine-tool setting are completed using the advanceddesign such as tooth root tilt and double taper, the calculation procedures is completedby VB. The study is done to select the reference point. firstly select the reference pointof calculate, solve the equation of the position and normal vectors,two sets of data areacquired, then calculate their mean as surface parameters of the reference point ofdesign that is the initial value to solve the nonlinear equations. A new method thatthrough tooth surface deviation anticipate contact position and whether theinterference of tooth surface is put forward, firstly according to the gear machine tool-setting get tooth surface of gear, then calculate benchmark of pinion by the globalconjugation, then according to the pinion machine tool-setting get tooth surface ofpinion, finally compare the tooth surface of pinion to benchmark of pinion toanticipate contact position and whether the interference of tooth surface. The effect ofthe cutter diameter and cutter number to contact pattern is studied when the pinion andthe gear use the same cutter; the influence of the total curvature of reference point fordesign,fitting line of contact pattern, the elliptical axis length on installation errorsensitivity and contact stability are analyzed when the cutter radius is different.In this paper the wheel blank design and machine tool-setting of spiral bevel gear is finished by “four cutter” method, and correctness is validated; using toothsurface deviation to forecast the contact and whether the interference of tooth surface,and validated by the instance; With tooth contact analysis the impact of cutterparameters on contact area is analyzed, when the smaller one, the total curvature ofreference point for design is bigger, the angle between contact trace and root angle isbigger, fitting line of contact pattern is better, the elliptical axis length of contactpattern is smaller and changes little, all those factors are good to reduce the influenceof installment error and improve the stability of contact.