Papers by Keyword: Boolean Operation

Abstract: A new modeling method for the variable ratio gear of the rack and pinion variable ratio steering gear was proposed in this paper. It was based on the characteristic that variable ratio gear pair meshing tooth profile surface are the envelope surface of each other and established a variable ratio gear three-dimensional model by simulating the gear machining process in CATIA and using Boolean subtraction operation. According to the related test standard of the variable ratio steering gear transmission ratio, a test bench was design and build, and the correctness of this modeling method was verified by comparing the designed variable ratio curve and the steering gear sample designed and processed by this method.

Abstract: A complex structure can be constructed by Boolean operations of geometric primitives such as cube, sphere, cylinder, and so on. However, Boolean operations cannot represent the structure in form of mathematical function. In this paper, we propose a new shape representation method that combines the Boolean operations with the KS function. Applications show that 2D and 3D engineering parts can be described by a single implicit KS function.

Abstract: Ballscrew drive mechanisms are widely used in the transmitting system of precision machine tools. The profile of the ball nut is a gothic curve combined by two equal radius arcs with offset centers. Most of gothic arc ball nuts are manufactured by form grinding, where the grinding wheel is shaped into the desired profile and the tool axis is tilted at the lead angle of the ball nut thread. In case of the internal ball nut grinding the high lead angle and long thread limits the manufacturing process. To avoid the collision between the internal surface of the workpiece and outer surface of the quill the optimal tilt angle is modified. The modified tilt angle affects to the profile of the formed grinding wheel. This paper presents a method for the generation of modified grinding wheel profile independently the tilt angle. The desired profile points are generated by solid boolean operations with programming of a parametric CAD system.

Abstract: This paper deals with prediction of improvement in surface roughness in helical scan grinding by simulation of virtual ground surface with a 3D-CAD model. It has been found that, by choosing the value of parameters of several grit conditions such as grit arrangement, protrusion height, inclination angle and so on, randomly for a real wheel, the maximum unevenness of the virtual ground surface and tendency of its change with feed angle nearly coincide with the surface roughness in the experiment of helical scan grinding. It is found that this simulation method is effective for the prediction of a surface ground by helical scan grinding.

Abstract: Based on the simulation principles of 3d software, a virtual grinding system is developed by means of united customized development on UG and applied to simulating CNC tool grinding machine manufacturing planar inserts with various linetypes. Tool-path data is read from the file and the process of NC grinding is simulated by the virtual system. Entity modelings of the inserts are obtained by Boolean operation in virtual environment, and the basis is presented for analyzing accuracy of the models.As testing efficiency of NC code and reliability of high speed grinding are improved.

Abstract: The porous media for liquid transporting and mechanical analysis, which are the hotspot studies in contaminant transport and machinery manufacturing, is hard to model in the computing simulation for the complexity of the media’s porosity. In the paper, an integrated approach is proposed to model the porous media with the framework of but not limited to sphere particles. Firstly, a series of particles are generated according to the grading curve in a closed box with the PFC3D, and then let the particles deposit freely for the gravity. After that the position and radium of each particle are exported to a file for import of AUTOCAD, where the particles are re-generated by the VBA script and the model for particles is constructed. The needed model is the porosity among the particles, so the model size is determined by a block and the model is gotten with the Boolean Operation which subtracts the particles from the block. And then with the different boundaries, the water transporting simulation in the porous media model is carried out with the Finite Volume Method (FVM). The results are proved reasonable by the previous studies.

Abstract: This paper deals with prediction of improvement in surface roughness in helical scan grinding by simulation of virtual ground surface with a 3D-CAD model. It has been found that, by choosing the value of parameters of four grit conditions such as grit arrangement, protrusion height, apex angle and inclination angle randomly to a real wheel, the maximum unevenness of the virtual ground surface and tendency of its change with feed angle nearly coincide with the surface roughness in the experiment of helical scan grinding. Furthermore, it is demonstrated that this analyzing method can be applied to R-shaped groove grinding and suggested that helical scan grinding is effective in grinding bearing grooves.

Abstract: Estimation of mechanism of surface finish improvement in helical scan grinding, a method in which a good surface finish is obtained besides keeping a high grinding efficiency, is performed based on the virtual grinding trace using a 3D-CAD model. In three grit models, (a) a single grit on a wheel, (b) plural grits arrangement on a helical line on the wheel circumference, and (c) multiple grit arrangement in a triangular pattern, virtual grinding traces and their unevenness or surface roughness are investigated. The virtual grinding trace in helical scan grinding is made by interference of grit trajectories, and the results of the analysis are very similar to experimental results.