Optimal Tool Orientation Research Articles

Non-uniform flank wear prediction and tool orientation optimization for ball-end tool 5-axis machining based on real cutting length calculation

Non-uniform flank wear prediction and tool orientation optimization for ball-end tool 5-axis machining based on real cutting length calculation

Chatter Avoidance by Spindle Speed and Orientation Planning in Five-Axis Ball-End Milling of Thin-Walled Blades

Abstract Selecting suitable cutting conditions is crucial in maintaining chatter stability and achieving acceptable surface quality. However, the selection of a constant set of cutting parameters is not feasible due to the time-varying dynamics of highly flexible thin-walled blades. This paper presents an optimal selection of tool orientation and spindle speed along the tool path as the metal is removed during the ball-end milling of blades. The effects of tool orientation and speed on the mechanics and dynamics of the ball-end milling process are formulated. Test case simulations are used to demonstrate the impact of tool orientation and speed on chatter stability and forced vibrations. The proposed algorithm identifies the optimal spindle speed and tool orientation by continuously updating the workpiece dynamics as a function of time and tool position to achieve improved stability and surface quality. Stability simulations are conducted to assess the optimization approach's performance, and the results are compared with experiments by machining a series of thin-walled twisted fan blades.

Tool orientation optimization method based on the best curvature matching

Tool orientation optimization method based on the best curvature matching

Piecewise Decoupling Tool Orientation Re-Scheduling for Four-Axis Reciprocal Toolpaths of Blades Based on S-θ Plane with Monotonicity Constraint

Reciprocal toolpaths with four-axis simultaneous motion of five-axis or four-axis machine tools are commonly used in the machining of blades which are widely applied in high-end equipment such as the aero-engine and the marine steam turbine. Due to the complex geometry of the blades, the tool orientation always suffers from frequent swing for this kind of toolpaths, which induces unnecessary acceleration/deceleration of the feed axes, thus degrading processing efficiency and quality. Although there are tool orientation optimization methods aiming at solving the above problem, they are mainly proposed for universal processing of the toolpaths for complex surfaces. Different from them, this paper proposes a piecewise decoupling tool orientation re-scheduling method for this kind of toolpath specifically, which takes full use of the characteristic of the reciprocal toolpaths of the blades, and takes the monotonous variation of rotation axes as an additional constraint. The re-scheduling process is realized based on the construction of a S-θ plane, where the scheduling problem is converted to the adjustment of a S-θ curve inside a feasible channel. Through two procedures, namely linearization scheduling and control-point assigning-based smoothing, the tool orientation path expressed by the S-θ curve can be effectively scheduled in a piecewise manner, and the smoothness between two adjacent pieces of the toolpaths can be ensured directly. The whole algorithm is lightweight and does not involve complex iterative operations or functional optimization solutions. Simulation and experimental tests verify the feasibility and superiority of this method. The results show that the machining efficiency of the blade is improved by 24.5%, due to the reduction of the requirement on highest feed-axis kinematics parameters after rescheduling. In addition, compared with the existing methods, the proposed method not only can improve the dynamics of feed axes in multi-axis machining, but also has advantages in computational complexity and monotonic variation property of the tool orientation.

Tool Orientation Optimization Based on Spatial Tractrix Method for Five-Axis CNC Machining with Ball End Cutters

Tool Orientation Optimization Based on Spatial Tractrix Method for Five-Axis CNC Machining with Ball End Cutters

Tool orientation optimization for the five-axis CNC machining to constrain the contour errors without interference

Tool orientation optimization with interference-free condition and good machining performance is one of the key issues in the five-axis machining processes. The existing tool orientation optimization algorithms usually reduce the contour errors indirectly through reducing each order derivative of the trajectory. In this article, a tool orientation optimization algorithm, which achieves the direct constraining of the tool tip and tool orientation contour errors while avoiding the interference between the tool and workpiece, is proposed for the first time. Two prediction models, i.e. an analytical model and a numerical model, are developed to predict the contour errors according to the tool orientation splines. Through considering multiple factors such as the real feedrate, the dynamics of the servo control system, the friction disturbance torque, the velocity, acceleration and jerk of the servo axes, the developed prediction models realize the precise prediction of contour errors. Through transforming the contour errors constraints and interference-free constraints into penalty terms, the constrained optimization problem is transformed to an unconstrained problem. Experiments validate that through optimizing the tool orientations, the maximum tool tip and tool orientation contour errors can be reduced by 52.2% and 75.6%.

Reinforcement learning–based tool orientation optimization for five-axis machining

Reinforcement learning–based tool orientation optimization for five-axis machining

Tool orientation optimization method based on ruled surface using genetic algorithm

Tool orientation optimization method based on ruled surface using genetic algorithm

Optimal tool orientation in 3 + 2-axis machining considering machine kinematics

In 5-axis machining, the initial orientation and position of the part in the fixture on the machine table are chosen to avoid collisions and to ensure that axes ranges are respected. However, kinematics of the machine is rarely considered for workpiece setup optimization although it affects the tool path execution and machining time. Indeed, for complex surfaces, actual feedrate is often lower than the programmed one and can present strong slowdowns, which are critical for the tool cutting conditions and therefore the part quality. This article investigates the use of kinematic manipulability criteria to determine the best orientation of the workpiece setup to maximize the actual feedrate and reduce machining time. The modelling of maximum velocity, acceleration, and jerk of each axis by means of polytopes makes it possible to take advantage of the whole kinematic space of the machine more intuitively. Simulations and experiments are carried out in 3 + 2-axis machining on test parts with a ball-end tool. For stretched surfaces, while the tool centre motion is given by the machining strategy, the tool axis orientation is optimized jointly with the workpiece setup. Experiments confirm that actual feedrate raises faster to better respect the programmed cutting conditions along each path. As feedrate is also higher, machining time is reduced significantly.

Theoretical approaches for determining machining conditions affecting a machined surface topography in filleted end milling

This study demonstrates theoretical approaches useful for practical determination of machining conditions affecting machined surface topography in filleted end milling. Tool orientation is investigated in particular. There are dominant processing parameters' optimizations from various perspectives, whereas a few comprehensive strategies have been proposed to determine machining conditions in filleted end milling. It is also practically scarce to discover the optimization strategy taking path interval determination as the theoretical fountainhead. In this study, theoretical approaches were described to determine machining conditions affecting machined surface topography in filleted end milling. After geometrical description was arranged to model multi-axis filleted end milling, multi-layer approach and the other computable parameters were proposed to obtain decent surface topography generated in filleted end milling. The analytical example focusing on tool orientation was provided with discussion. As a result, some characteristics of theoretical approaches were revealed with the visual evidences. Finally, optimal tool orientation will be arranged based on the findings.

Determination of the cutting force components while milling cylindrical surfaces with an oriented tool

Purpose. Construction of a general modular mathematical spatial model of the removal allowance process and shaping when milling round surfaces of rotation, such as camshaft necks, cylindrical surfaces of gearbox shafts and others. Determination of the components of the cutting forces when machining with crossed axes of the milling cutter and part in order to use the results when assigning machining modes. Methodology. Theoretical development of a modular mathematical model of the removal allowance process and shaping during milling of cylindrical surfaces was carried out using a matrix apparatus for converting coordinate systems. Unified modules were developed: instrumental, orientation and shaping, which allowed us to describe the processing of the part more clearly. All calculations were performed in the mathematical package Mathcad. Using the functions available in the package, a graphical representation of the mathematical model of the tool and machined surfaces was obtained. Using the logical blocks developed in the program, the characteristics of the treated surface were investigated, such as roughness in the axial and radial planes. The influence of the tool orientation angle and the number of cutter teeth on the roughness of the machined surface was investigated. The known formulas for calculating the cutting forces during milling are specified. Findings. A general modular mathematical spatial model is constructed of the removal process of an allowance and formation at milling by the oriented tool of round surfaces of rotation, such as necks of camshafts, cylindrical surfaces of shafts of transmissions and others. The roughness parameters of the treated surface are determined. The outflow of the tool characteristics and the angle of its orientation on the geometric roughness in the axial and radial sections is investigated. The area of the layer cut off by one tooth of a mill is defined. The calculation formulas are specified for finding the components of cutting forces during milling. Originality. A modular spatial model of the process of milling cylindrical surfaces with an oriented tool is proposed, on the basis of which the components of cutting forces are calculated, which can be used in designing new tools and improving machining conditions by the existing ones. Practical value. Based on the use of modern computer facilities and software, the developed calculation program allows controlling the process of forming cylindrical surfaces during their milling with an oriented tool. It also allows predicting the initial machining accuracy by determining the parameters of geometric roughness in axial and radial sections. This makes it possible to choose the optimal tool orientation angle, milling cutter parameters and cutting modes to achieve high productivity and processing quality.

Tool orientation adjustment for improving the kinematics performance of 5-axis ball-end machining via CPM method.

• A novel CPM method is proposed to adjust tool orientations for 5-axis ball-end machining. • Linearization strategy developed can simplify greatly the solving of the CPM model. • Kinematics performance is improved while maintaining the expected cutting performance. • Simulation and actual milling testings are conducted to validate the proposed method. For 5-axis ball-end machining, it is desired to maintain the expected cutting performance of tool orientation when adjusting tool orientation for improving the motions of rotary axes of 5-axis machine. For this purpose, a cutting performance maintained (CPM) method is proposed to adjust the tool orientations, the objective of which is to minimize the sum of the absolute deviations between the initial and adjusted coordinates of the rotary axes while improving the kinematics performance of the rotary axes and ensuring no machining interferences. In order to speed up the solving of the optimization objective, the analytical linear representations for the drive limits of rotary axes and especially irregular geometry feasible domains (GFDs) of tool orientations are first discussed in detail. The nonlinearity of the objective function is then eliminated by introducing two new auxiliary variables for further simplifying the computation of optimal tool orientation. After rewriting the drive limits and GFD constraints with the two auxiliary variables, the linear objective function can be efficiently solved by the simple linear programming method. The tool orientations adjusted by the proposed CPM method can not only improve the interference-free motions of the rotary axes, but also can maintain the expected cutting performance. Finally, the computer simulation and real milling were conducted to validate the proposed method.

Tool Orientation Optimization and Path Planning for 5-Axis Machining

Tool path generation is a fundamental problem in 5-axis CNC machining, which consists of tool orientation planning and cutter-contact (CC) point planning. The planning strategy highly depends on the type of tool cutters. For ball-end cutters, the tool orientation and CC point location can be planned separately; while for flat end cutters, the two are highly dependent on each other. This paper generates a smooth tool path of workpiece surfaces for flat end mills from two stages: Computing smooth tool orientations on the surface without gouging and collisions and then designing the CC point path. By solving the tool posture optimization problem the authors achieve both the path smoothness and the machining efficiency. Experimental results are provided to show the effectiveness of the method.

Geometric error compensation of five-axis ball-end milling based on tool orientation optimization and tool path smoothing

Geometric error compensation may affect the quality of the machined surface textures due to the arbitrary adjustment of cutter locations. This paper proposes one geometric error compensation of five-axis ball-end milling in order to reduce the influences on the machined textures, including the tool orientation optimization of single cutter location and the smoothing of the overall tool path. At first, tool center limitation method is introduced briefly with the construction of the new cutter location. Second, CSO (chicken swarm optimization)-based tool orientation optimization is proposed for geometric error compensation. The inclining angle and the rational angle around the nominal tool orientation are chosen as the chicken. The tool center limitation method is used for the calculation of the fitness of the chicken. Next, the smoothing of the whole tool path is established to avoid the mutation of rotation angles including the evaluation of the smoothness and the inserting and optimizing of the new cutter locations. Finally, simulation and cutting experiments are proposed on the SmartCNC500_DRTD machine tool to testify the effectiveness of the geometric error compensation.

Reducing roughness of freeform surface through tool orientation optimization in multi-axis polishing of blisk

In the field of multi-axis polishing of blisk, path planning is one of the core contents. It not only determines the polishing efficiency but also affects the polishing accuracy. However, as one of the most important roles, the influences of tool orientation on freeform surface roughness have not been paid enough attention. To address that, a method to reduce the roughness through tool orientation optimization is proposed in this paper. Firstly, the model of polishing freeform surface with abrasive cloth wheel is established to describe the influence of tool orientation on the uniformity of material removal. It is described with the distribution of compression deviation along the contact curve and the trajectory of grain. Based on that, the model of tool orientation optimization is established and solved with the PSO (particle swarm optimization) method. Where, both the deviations of maximum compression and ideal angle are taken as evaluation indicators. At last, the effectiveness of the proposed method is verified with a plane and an open blisk respectively. Besides, the results also show that both the deviation of compression and the angle between tool orientation and feed direction can affect the roughness of polished surface. And the latter is more significant.

Оценка шероховатости при пятикоординатном чистовом фрезеровании поверхностей сфероцилиндрической фрезой

Unlike three-axis machining, five-axis machining allows the end tool or workpiece to be oriented at any angle relative to the machine axis OZ. It can be achieved by changing the values of the tool tilt angle and lead angle relative to the surface normal in the contact zone of the tool surface and the workpiece, taking into account the direction of the table feed. The article presents experimental results of analyzing the influences of tool orientation on transverse roughness during ball end milling using 2-flute and 4-flute 8 mm diameter mills. The analysis the arithmetic mean deviation of the assessed profile at various values of tool tilt angle and lead angle showed that the position of the tool point with a zero cutting speed significantly affects the surface quality. The results of the evaluation of the tool orientation influence on the surface roughness enable the selection of optimal tool orientation angles when developing control programs for end milling of free-form surfaces on five-axis CNC milling machines.

Tool Orientation Optimization for Disk Milling Process Based on Torque Balance Method

Disk milling strategy has been applied in grooving for decades for its capacity to provide huge milling force on difficult-to-cut material. However, basic research on the tool orientation of the disk milling cutter for the disk milling process on the milling free surface, especially on the free surface of the blisk, is still lacking in previous studies. In this study, the minimum residual amount after the disc milling process is used as an optimization target to obtain the optimal tool orientation of the disc cutter. To address the problem mentioned above, a torque balance method, including a torque balance algorithm and concentric circle ray point (CCRP) method is proposed. The torque calculation and torque balance problem are solved by the torque balance algorithm and the problem of generating random points to cause torque symmetry is solved in the CCRP method. Based on the secondary development of UG NX software, a series of tool orientation of disk milling cutter are calculated. Finally, the torque balance method is compared with steepest descent method, Newton method, and conjugate gradient method in the aspects of calculation accuracy, operation speed, and convergence speed. However, both the calculation speed and the convergence speed are better than the other three algorithms. Compared with the other three methods, the operation speed of the torque balance method is reduced by 0.35 times, 1.5 times, and 2.25 times. The results prove the feasibility of the torque balance method in solving the problem of tool orientation optimization of the disk milling cutter.

Tool orientation optimization considering cutter deflection error caused by cutting force for multi-axis sculptured surface milling

Multi-axis milling (especially five-axis) is in the ascendant for high precision manufacturing of a product with a sculptured surface such as ship propeller, owing to its multi-axis linkage and resulting outstanding superiorities. Needs of a faster-improving manufacturing level of sculptured surface milling are derived by higher performance requirement of complicated equipment, which makes the planning of tool orientations more significant and challenging. This paper builds a tool orientation optimization model with inclusion of the influence of deflection error caused by cutting force to achieve better machining precision controlling in five-axis sculptured surface milling. The basic idea of the optimization method is described firstly, followed by the prediction of cutter deflection error. Then determining processes of the related subset to restrain the tool orientations are developed. Lastly, comparative experiments are designed and performed through milling a propeller rotor possessing numerous blades in a five-axis machining center. By comparison with several other tool orientation methods, the average values and volatility of deflection error are both suppressed better utilizing the optimization modeling. The experiment results reflect that it is insufficient to consider single geometric constraint or kinematic constraint, and greater attention should be paid to the role of cutter deflection caused by cutting force in planning the tool orientations.

A Gouge-Free Tool Axis Reorientation Method for Kinematics Compliant Avoidance of Singularity in 5-Axis Machining

Abstract When a cutter traverses a region local to the singularity in 5-axis machining, the stability of machine tool motion may be violated and inevitably lead to a reduction in machining quality and accuracy. In this paper, the underlying cause of the singular machine behaviors is first investigated by differentiating tool path motions, on the basis of the tool path motion expressions in part and machine coordinate systems. A further investigation indicates abrupt kinematic changes to be inevitable when the rotary axes approach a singularity. To eliminate such possible singular risks in 5-axis machining, a local tool path modification method is proposed by adjusting the two rotary axes out of a singular configuration. The critical kinematics smoothing and the consequent gouging concerns resulting from reorientation are comprehensively incorporated in the process of singularity avoidance, by means of a novel tool orientation optimization model. Specifically, the algorithm starts with the determination of an appropriate adjustment range in a simple yet effective manner, and then the primary rotary axis is adjusted in a constrained region away from zero, so as to avoid singularity. After that, the second rotary axis is accordingly adjusted, with no gouging requirements being violated. In this way, singularity problems in 5-axis machining are solved, and both the machine axes kinematics and surface gouging errors are under control. Machining simulation and laboratory experiments were conducted to validate the effectiveness of the proposed method.

Влияние ориентации инструмента на силы резания при концевом фрезеровании

This article presents the results of single-factor modeling and analysis of the influence of tool orientation with regard to the tilt angle and lead angle, on cutting forces when finish milling by a ball end cutter. The program NX 10 is used to build boundaries and contact areas of the tool and the workpiece, and the SIMULIA ABAQUS software is used to create a three-dimensional finite element model and determine the cutting forces. Graphs that describe dependencies of the cutting forces on the tool rotation angle are obtained for different orientations of the tool axis relative to the surface normal. The computational results will allow transition to the two-factor analysis of the influence of tilt angle combinations on the cutting forces and the determination of the optimal tool orientation during five-axis milling with maximum productivity.