Impellers are important components in the field of precision machine, energy technology, and aerospace industries. Due to their complex geometries and a higher degree of interference, multi-axis machines are requested to product impellers with desired accuracy. The object of this thesis is to improve the five-axis machining efficiency and accuracy. The involved techniques include: the construction of equal depth and equal width tool paths in rough machining, the methods for interference check and avoidance, error evaluation and control of chordal deviation and scallop height, as well as three and five dimension NURBS (Non-uniform Rational B-splines) tool paths generation by a least squares method.

This thesis presents models and algorithms necessary to simulate the five-axis flank milling of jet-engine impellers in a virtual environment. The impellers are used in the compression stage of the engine and are costly, difficult to machine, and time-consuming to manufacture. To improve the productivity of the flank milling operations, a procedure to predict and optimize the cutting process is proposed. The contributions of the thesis include a novel cutter-workpiece engagement calculation algorithm, a five-axis flank milling cutting mechanics model, two methods of optimizing feed rates for impeller machining tool paths and a new five-axis chatter stability algorithm. A semi-discrete, solid-modeling-based method of obtaining cutter-workpiece engagement (CWE) maps for five-axis flank milling with tapered ball-end mills is developed. It is compared against a benchmark z-buffer CWE calculation method, and is found to generate more accurate maps. A cutting force prediction model for five-axis flank milling is developed. This model is able to incorporate five-axis motion, serrated, variable-pitch, tapered, helical ball-end mills and irregular cutter-workpiece engagement maps. Simulated cutting forces are compared against experimental data collected with a rotating dynamometer. Predicted X and Y forces and cutting torque are found to have a reasonable agreement with the measured values. Two offline methods of optimizing the linear and angular feeds for the five-axis flank milling of impellers are developed. Both offer a systematic means of finding the highest feed possible, while respecting multiple constraints on the process outputs. In the thesis, application of these algorithms is shown to reduce the machining time for an impeller roughing tool path. Finally, a chatter stability algorithm is introduced that can be used to predict the stability of five-axis flank milling operations with general cutter geometry and irregular cutter-workpiece engagement maps. Currently, the new algorithm gives chatter stability predictions suitable for high speed five-axis flank milling. However, for low-speed impeller machining, these predictions are not accurate, due to the process damping that occurs in the physical system. At the time, this effect is difficult to model and is beyond the scope of the thesis.

This thesis presents models and algorithms necessary to simulate the five-axis flank milling of jet-engine impellers in a virtual environment. The impellers are used in the compression stage of the engine and are costly, difficult to machine, and time-consuming to manufacture. To improve the productivity of the flank milling operations, a procedure to predict and optimize the cutting process is proposed. The contributions of the thesis include a novel cutter-workpiece engagement calculation algorithm, a five-axis flank milling cutting mechanics model, two methods of optimizing feed rates for impeller machining tool paths and a new five-axis chatter stability algorithm. A semi-discrete, solid-modeling-based method of obtaining cutter-workpiece engagement (CWE) maps for five-axis flank milling with tapered ball-end mills is developed. It is compared against a benchmark z-buffer CWE calculation method, and is found to generate more accurate maps. A cutting force prediction model for five-axis flank milling is developed. This model is able to incorporate five-axis motion, serrated, variable-pitch, tapered, helical ball-end mills and irregular cutter-workpiece engagement maps. Simulated cutting forces are compared against experimental data collected with a rotating dynamometer. Predicted X and Y forces and cutting torque are found to have a reasonable agreement with the measured values. Two offline methods of optimizing the linear and angular feeds for the five-axis flank milling of impellers are developed. Both offer a systematic means of finding the highest feed possible, while respecting multiple constraints on the process outputs. In the thesis, application of these algorithms is shown to reduce the machining time for an impeller roughing tool path. Finally, a chatter stability algorithm is introduced that can be used to predict the stability of five-axis flank milling operations with general cutter geometry and irregular cutter-workpiece engagement maps. Currently, the new algorithm gives chatter stability predictions suitable for high speed five-axis flank milling. However, for low-speed impeller machining, these predictions are not accurate, due to the process damping that occurs in the physical system. At the time, this effect is difficult to model and is beyond the scope of the thesis.

This thesis presents models and algorithms necessary to simulate the five-axis flank milling of jet-engine impellers in a virtual environment. The impellers are used in the compression stage of the engine and are costly, difficult to machine, and time-consuming to manufacture. To improve the productivity of the flank milling operations, a procedure to predict and optimize the cutting process is proposed. The contributions of the thesis include a novel cutter-workpiece engagement calculation algorithm, a five-axis flank milling cutting mechanics model, two methods of optimizing feed rates for impeller machining tool paths and a new five-axis chatter stability algorithm. A semi-discrete, solid-modeling-based method of obtaining cutter-workpiece engagement (CWE) maps for five-axis flank milling with tapered ball-end mills is developed. It is compared against a benchmark z-buffer CWE calculation method, and is found to generate more accurate maps. A cutting force prediction model for five-axis flank milling is developed. This model is able to incorporate five-axis motion, serrated, variable-pitch, tapered, helical ball-end mills and irregular cutter-workpiece engagement maps. Simulated cutting forces are compared against experimental data collected with a rotating dynamometer. Predicted X and Y forces and cutting torque are found to have a reasonable agreement with the measured values. Two offline methods of optimizing the linear and angular feeds for the five-axis flank milling of impellers are developed. Both offer a systematic means of finding the highest feed possible, while respecting multiple constraints on the process outputs. In the thesis, application of these algorithms is shown to reduce the machining time for an impeller roughing tool path. Finally, a chatter stability algorithm is introduced that can be used to predict the stability of five-axis flank milling operations with general cutter geometry and irregular cutter-workpiece engagement maps. Currently, the new algorithm gives chatter stability predictions suitable for high speed five-axis flank milling. However, for low-speed impeller machining, these predictions are not accurate, due to the process damping that occurs in the physical system. At the time, this effect is difficult to model and is beyond the scope of the thesis. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

To further the research done in machining complex surfaces, Jensen [1993] developed an algorithm that matches the normal curvature at a point along the surface with the resultant radius formed by tilting a standard flat end mill. The algorithm called Curvature Matched Machining (CM2) is faster and more efficient than conventional three-axis machining [Jensen 1993, Simpson 1995 & Kitchen 1996]. Despite the successes of CM2 there are still many areas available for research. Consider the machining of a mold or die. The complex nature of a mold requires at least 20-30 weeks of lead time. Of those 20-30 weeks 50% is spent in machining. Of that time 50-65% is spent in rough machining. For a mold or die that amounts to 7 to 8 weeks of rough machining. If one could achieve as much as a 10-15% reduction in machining time that would amount to almost one week worth of time savings. As can be seen, small improvements in time and efficiency for rough machining can yield significant results [Fallbohmer 1996]. This research developed an algorithm that focused on reducing the overall machining time for parts and surfaces. Particularly, the focus of this research was within rough machining. The algorithm incorporated principles of three-axis rough cutting with five-axis CM2, hence Rough Curvature Matched Machining (RCM2). In doing so, the algorithm ‘morphed‘ planar machining slices to the semi-roughed surface allowing the finish pass to be complete in one pass. This roughing algorithm has significant time-savings over current roughing techniques.

In this thesis, an actuation system is developed for a Two-Axis Gyroscopic (TAG) adapter. This adapter is a fixture with two auxiliary axes which is used for the Single Point Incremental Forming (SPIF) technique to enhance a three-axis mill to have five-axis capabilities. With five-axis mill capabilities, variable angles between line segments of the toolpath and the tool can be obtained. To achieve specialized angles between a line segment and the SPIF tool, the sheet is rotated. Inverse kinematic equations for the TAG adapter are derived to calculate the required rotations for the TAG adapter’s auxiliary axes for a line segment of a toolpath. If the next line segment requires a different orientation of the sheet, the sheet is rotated while the tool follows the rotation of the sheet to maintain its position at the connecting point of the line segments of the toolpath. Five equations of motions are derived to calculate the three translations of the mill and two rotations of the TAG adapter’s frames, during forming. A toolpath execution algorithm is implemented in MATLAB which uses the five equations of motion to execute a toolpath. The algorithm generates an array of data points that can be used by a Computer Numerically Controlled (CNC) machine to follow a desired path. A visual representation for the execution of the toolapth is implemented in MATLAB and is used to illustrate the successful completion of a toolpath. A computer controlled motor system is selected and tested in this thesis which will ultimately be integrated with a worm gear system and a CNC machine to develop a full CNC actuation system. / UOIT

Impellers are important components in the field of aerospace, energy technology, and precision machine industries. Considering the high accuracy and structural integrity, impellers might be manufactured by cutting. Due to their complex geometries and high degrees of interference in machining, multi-axis machines are requested to produce impellers. The object of this thesis is to improve 5-axis tool paths for surface quality of impellers by smoothing point cutting tool paths in terms of linear segments and B-Splines and by using flank milling technologies with linear segment and B-Splines tool paths. Experimental results show that the surface quality of impeller blades can be improved by point cutting with smoothed tool paths and by flank milling. Moreover, the required milling time can be reduced by 18 percent and 13percent based on smoothed linear tool paths and smoothed B-Splines tool paths, respectively.

Thesis consists of theoretical introduction to programming in G-code, underlying mathematical principles and methods how to program general curves and surfaces. There are seven exam

As competition grows among manufacturing companies, greater emphasis has recently been placed on product aesthetics and decreasing the product development time. This is promoting and standardizing widespread use of sculptured surface styling within product design. Therefore, industries are looking for high efficiency machining strategies for sculptured surface machining (SSM). Many researchers have produced various methods in tool path generation for SSM. Five-axis curvature matched machining (CM2) is the most efficient. With the widespread use of 5-axis mill in industries, CM2 is a better solution for improving the machining efficiency for product concept models. CM2 has very good performance for global machining of single patch surface or a quilt of simple sculptured surface patches. But when CM2 is used to generate tool paths for global machining of a large region of complex sculptured surface such as the top or side skins of a vehicle, there will be some limitations, that is, the performance will be influenced greatly in some steep areas where the lead angle of the tool becomes larger to match the curvature or avoid gouging. Larger lead angles mean smaller effective curvatures at the leading edge of the tool bottom where it contacts the part surfaces. Therefore, the density of CM2 tool path is very high in these steep regions. By setting a smaller upper limit for the lead angle, the density of tool path will not be very high in the steep regions, but there will be some uncut materials. This thesis focuses on how to determine the uncut or rework areas of the previous CM2 and how to define the boundary of these regions. Strategies for generating more efficiency CM2 tool paths are also discussed. These methods will be tested by applying finish global machining to a one-fourth scale Ford GT model.

The aim of this thesis is the design of the rotary tilting table controlled the fourth and fifth axis for CNC centrum.První part includes the search for pivotally tilting tables. The second part includes the choice of technical paremetrů pivotally tilting table for selected CNC center, design of possible options , selection of appropriate options, design of the selected option.