The Investigation of manufacturing of spur gear with demontable teeth

SUMMARY (PhD: Thesis) THE INVESTIGATION OF MANUFACTURING OF SPUR GEAR WITH DEMONTABLE TEETH Cebeli OZEK Institute of Science and Technology Mechanical Education Department 2002, Page 173 The need for special machine tools in accurate manufacturing of spur gears is a big problem for the ones who need these kinds of gears in small amounts, in the industry. Spur gears can be manufactured in milling machines with module cutters or special machine tools but the gears manufactured in these machines are inefficient and make the life of the matched gear extensively shorter due to the low quality or accuracy. Since the number of the special gear manufacturing machines is limited in our country, the manufacturing of spur gears is an important problem for the small workshops. This study, considering the widespread in CNC milling machines in the country, new types of spur gears and their manufacturing in CNC milling machines were investigated. In the first chapter of this study, the subject was introduced. In the second chapter, the fundamental information on the spur gears was given and all the manufacturing methods of the spur gears were dealt with. In the third chapter, the types of the spur gears with changeable teeth were discussed and determined (segmented, pinned and fluted types). The dimensioning of these gears was performed. In the segmented type, the segmented groove was machined both in the single tooth and the gear body. The segmented was placed in the cover. In the fluted type, the wedge groove was machined on the single tooth while the wedge was on the gear body. In the pinned type, pin holes were drilled in the single tooth and the pin grooves were machined in the gears body. Separate machining programmes were prepared with respect to the evolvent profile of the teeth for the each individual tooth in AUTOCAD 2000 and CNC programmes. Each individual tooth was machined by using single point programmesVI with G01, G02 and G03 codes. For each body model, separate C programmes were prepared considering the geometrical dimensions of the different individual tooth by using C programming language. For this, the dimensioning was performed for a spur gear with a module of 8 mm and teeth number of 10. First, the geometrical dimensions of the gears were calculated and technical drawings were prepared. Then, all the gears were manufactured of fiberglass or polyethylene in a gear machine tool in Elazığ. Of the same material, CNC rnachining programmes for each tooth profile (using X-Y coordinates and arc radius R of the evolvent) according to the drawing rule were prepared. These programmes were loaded a vertical CNC milling machine (DYNA 2900 MYTE) and the teeth were manufactured individually. The same programme was loaded to a vertical CNC milling machine (Fanuc OMt). This time the individual teeth were machined of C8620 material with the programmes for the right and left evolvent profiles. The manufactured individual teeth were placed in the gear bodies. Then, in order to prevent sliding they were fixed with rings, pins or wedges in the minimum equal spacing, considering gears rule. A hydraulic pump was produced to observe the gears in service. In the fourth chapter, the gear control distances of the gears were measured. Evolvent profile and the angular of direction were checked. The time of production was determined. The surface roughness of the teeth manufactured was measured. The teeth were also examined in a tension machine in order to check the tension strength. The model bearing maximum load was chosen. The gears were run in the hydraulic pump at the certain speeds such as 540, 800, 1200, 1700 and 2500 rpm. The volumetric flow of hydraulic pump were measured and compared for the gear types used. These gears were also compared with the one manufactured in gear manufacturing machine. The theoretical and experimental flows were compared graphically. In the fifth chapter, the problems faced during the manufacturing were presented. The most proper tooth type was determined with respect to the gear check distance, flow and surface roughness. In the sixth chapter, the general results and suggestions have been determined. Key Words: Demountable Spur Gear, CNC, Manufacturing