Machining technology and NC machining of straight bevel gear split gear blank cutting

According to the structural characteristics and the complexity of the tooth profile of the split straight bevel gear, the vertical CNC three-axis machine yk3140 is selected as the equipment for the gear cutting of the straight bevel gear. In order to improve the machining efficiency and ensure the accuracy of the tooth surface, rough machining is first followed by finish machining, and the cutting method is milling.

During machining, in order to ensure that the tool is not damaged, the diameter of the selected tool should be as large as possible, but the structural size of straight bevel gear blank will limit the diameter of the tool in the actual cutting process. According to the slot width and tooth height of the straight bevel gear, the rod cutter with diameter of 10mm shall be selected for rough machining, and the materials in the slot shall be cut off layer by layer during machining; The ball end milling cutter with a diameter of 8mm shall be selected for finishing machining. The cutting speed during rough and finish machining is 1200R / min. the cutting depth of each cutter during rough machining is 0.2mm and that of each cutter during finish machining is 0.1mm; During machining, the cutter shaft of the ball end milling cutter maintains a posture perpendicular to the upper and lower surfaces of the straight bevel gear blank, and moves back and forth along the tooth width direction to finish the rough machined tooth surface, so as to make the tooth surface more smooth and flat.

(a) Rough machined tooth surface (b) Tooth surface after finishing

At present, the NC machining code of split straight bevel gear can determine the coordinates of the tool center by calculating the tool position, and compile the program according to the motion law of the tool center coordinates. However, the calculation amount of manual programming is large, it takes a long time, and there will be errors in the calculation process. Therefore, this paper uses the cam module of UG to realize the tool path simulation of rough and finish machining of straight bevel gear and the generation of NC program. The specific steps are as follows: open the 3D model created before in UG, switch the existing “modeling” module to the “machining” module, define the programming origin and machining coordinate system in the geometric view of the process navigator of this module, and define the “blank” and “part” required for machining simulation; Create the tools required for rough and finish machining in the machine tool view, add the processes required for gear cutting in the program view, and view the dynamic results of the simulation machining after generating the tool path, as shown in the figure.

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