The objective of this study is to investigate the influences of the shape of grinding wheel to the teeth profile and the contact pattern of Curvic couplings. Firstly, the equations of concave and convex teeth profiles are successfully derived by using coordinate transformation technique. Then, assembly errors and shape parameters errors of the grinding wheel are introduced, and the error-involved teeth profiles equations are also obtained. Finally, the optimization technique is employed to find the optimized parameters of the grinding wheel such that Curvic couplings with prescribed proper mating conditions can be manufactured. The influences of the each parameter of grinding wheel with respect to the associated contact condition are also analyzed. The radii of grinding wheels for both concave and convex teeth, and the center distance between the grinding wheel and coupling blank are identified to significantly influence the contact area. A computer program for obtaining the optimum profile of grinding wheel involved error settings has been developed by using Visual Basic language.

Curvic couplings have been widely applied to various industrial applications. Presently the Gleason No.120 special grinding machine developed by Gleason Works Co. is one of the commonly used machine tool for the curvic coupling manufacturing. On the other hand, in response to the issue of improving the domestic design and manufacturing ability, an alternative manufacturing method of curvic coupling is introduced in this study. In this study the geometrical characteristics of the novel gear profile are investigated. Firstly, applying the spatial transformation matrix theorem to the relationship between the cutting tool path and the cutting tool position, the cutting tool profile equation of curvic coupling is successfully derived. Secondly, the mathematical model of the envelope surface of the generating tool, or generally being called the gear surface, is constructed based on the trajectory equation of the generating tool motion and the tool-workpiece meshing equation. Finally, the solid model is established based on the obtained mathematical model, and the comparison works with the conventional curvic coupling are also carried out. The analysis of gear surface is graphically depicted with respect to the various machining parameters. It is believed that this thesis provides a useful tool for the following studies of curvic couplings for the different demand of application fields.

The thesis is performed in order to improve the curvic coupled engagement of a dog clutch situated in the transfer case of a truck. The dog clutch is used to engage the so called all-wheel-drive system of the truck. If the driver tries to engage the all-wheel-drive when truck’s rear wheels already skid, due to a slippery surface a relative rotational speed in the dog clutch will occur. This relative rotational speed will cause the dog clutch to bounce back of itself before engagement, or to not engage at all. The dog clutch has been redesigned to prevent this. Dynamic simulations using MD Adams have been made for the existing model, for the models created in previous works, and for the new model in order to figure out which of them will show the most stable engagement, at high relative rotational speed. The implemented simulations show that better results can be obtained. Separation into two parts of the disc pushed by the fork, shows that dog clutch’s engagement is faster and more stable, comparing to the original model and the other created models. The new model shows better coupling in the whole range of the relative rotational speed from 50 up to 120rpm.

The thesis is carried out in order to improve the transfer case in trucks with all-wheel-drive. When the truck loses traction at the rear wheels, due to slippery surfaces, wheel-spin occurs. If the driver engages the all-wheel-drive at a point where traction already has been lost, a relative rotational speed in the dog clutch will occur. If this relative speed is too high the dog clutch bounces of itself before coupling or it does not couple at all. To avoid this problem, the geometry of the teeth is modified. FE simulations are done for the existing model as well as for all the new models in order to find out which of them can handle the highest relative rotational speed. The results show that the original model is not the best one. Simple modifications of the teeth’s chamfer distance and chamfer angle shows that the dog clutch can handle up to 120 rpm of relative rotational speed whereas the original model only handles 50 rpm. / Examensarbetet är utfört för att försöka förbättra inkopplingen av allhjulsdrift på lastbilar. När en lastbil kör på halt eller löst väglag kan hjulspinn uppstå vid bakhjulen. Om föraren kopplar in allhjulsdriften när hjulen börjat slira uppstår en relativ rotationshastighet mellan halvorna i klokopplingen. Om denna relativa rotationshastighet är för hög kommer halvorna i kopplingen studsa mot varandra innan de kopplas ihop eller inte koppla ihop alls. För att undvika detta problem har klokopplingens tandgeometri modifierats. FE simuleringar är gjorda på den ursprungliga modellen samt alla nya modeller för att ta reda på vilken som kopplar vid högst relativa rotationshastighet. Resultaten visar att förbättringar kan göras. Enkla modifieringar på avfasningarnas avstånd och vinklar visar att klokopplingen kan klara upp till 120 rpm i relativ rotationshastighet jämfört med den ursprungliga modellen som endast klarar 50 rpm.