Ball-end Cutter Research Articles

Modeling/analysis of four-half axis machine tool via modified denavit-hartenberg notation

Four-half axis and five-axis machine tools have five moving members (X, Y, Z, A, and B). Four-half axis systems cannot simultaneously operate the B axis with translational or rotational axes, thus limiting tool machining ability and complicating NC codes. This study employs modified Denavit-Hartenberg notation to model four-half axis machine tool kinematics and obtain corresponding ability matrixes. NC data equations for the A, B, X, Y, and Z axes with respect to the workpiece frame are derived by inverse kinematics. Machine tool active parameters and workpiece home position are simultaneously measured by using a ball-end milling cutter as a measuring probe.

Based on the Titanium Alloy Milling Forces Modeling and Simulation Study

A common mechanical model of ball-end milling cutter is analyzed in this paper, and take advantage of the orthogonal experiment method to make experiment of milling to identify the milling force coefficients with the titanium alloy material as the test object.Then put the coefficients in the mechanical model of ball to use MATLAB software to predict the milling force. The results of experiment and results of simulation are basically identical, it shows that the mechanics model of ball milling is proved to be correct.

Study on Cutting Parameters Optimization of Ball-End Cutters Milling for 2A70 Aluminum Alloy

Based on experiments of ball-end cutters milling for 2A70 aluminum alloy, the prediction model of surface roughness for 2A70 aluminum alloy is established by using of regression analysis method of least square. Aiming at the actual milling problem in the enterprise the cutting parameters are optimized by using of optimization tool-box of MATLAB software, in the process of solving optimized parameters the machining efficiency is set as the objective function and surface roughness prediction model is set as the constraint condition. The optimized cutting parameters can greatly improve the machining efficiency in the premise of ensuring the quality of machined surface, and it provides the important theory evidence and case reference for NC machining enterprises to reduce production costs.

Micro Ball End Milling of Nickel-Based Alloy for Laval Nozzle

The performance of the micro nozzle is determined primarily by its machined surface topology and geometric profile. A circular cross-section micro-Laval nozzle is modeled and studied by using numerical simulation in this paper. The real residual height and residual area of machined nozzle surface with ball-end milling cutter are proposed. A micro-Laval nozzle was machined successfully. It is found that the ball end milling cutter with large radius is suitable for finishing operations in the viewpoint of nozzle performance. Moreover, the serial process of drilling and milling has been proved by experiments with which both high-level machining accuracy and performance can meet the nozzle requirement.

Analysis to Milling Force Base on AdvantEdge Finite Element Analysis

Aiming at NC milling processing simulation problem, a ball-end cutter milling force model is established, the numerical simulation analysis of aluminum alloy AL2024 milling process is conducted by using the finite element analysis software AdvantEdge finite element analysis. Focus on the Milling force simulation, the size of the milling force is obtained by simulating calculation. Using the same cutting parameters for milling experiment, the results show that simulation analysis of the cutting force values ​​are in good agreement with the experimental results，the milling force model prior established is correct. The research laid a foundation for the perfect CNC milling simulation system.

Path Planning for Circular Cutter Envelop Milling of Steam Turbine Blade

In order to solve the problem of poor steam turbine blade processing efficiency, and on the basis of analyzing the turbine blade surface and the existing processing methods, a model of circular cutter turbine blade machining is built. By comparing the tool paths of horizontal and vertical section envelope machining, choosing quasi-vertical cross section envelope machining method and utilizing the original datum and NURBS surface matching mathematic methods, this paper provides an algorithm of residual height calculating, and based on this, the tool path can be planned. Datum show that, the tool path of circular cutter machining blades is much longer than the tool path of ball-end cutter envelop milling machining blades, and the machining efficiency is also highly enhanced.

Toolpath dependent chatter suppression in multi-axis milling of hollow fan blades with ball-end cutter

Aiming at the issue of toolpath dependent machining vibration in multi-axis milling of hollow fan blades, this paper presents an optimal selection method of cutting parameters based on single-line toolpath to suppress cutting chatter. Firstly, the impact of hollow structure on the blade structural modal was analyzed by using the modal analysis method. And the unstable regions of hollow blade surface have been predicted, which were prone to induce machining deformation and vibration. Secondly, the relationship between the hollow structure and the dynamic characteristics was revealed by analyzing the dynamic responses to the different cutting positions of blade surface. Thirdly, the optimization of cutting parameters based on single-line toolpath was proposed by establishing the 3D stability lobe diagram. Finally, the feasibility and effectiveness about the analysis of dynamic characteristics and the suppression method of cutting chatter were verified by a milling experiment of hollow blade.

Tool wear model based on least squares support vector machines and Kalman filter

In this study, the least squares support vector machines (LS-SVM) and Kalman filter (KF) technique are used to establish the tool wear estimation model. Tool wear prediction model, based on LS-SVM, is given to describe the mapping relationship between input–output factors. The cutting conditions (feed rate, cutting speed, and depth of cut), cutting time, and wear position constitute the input factors and tool wear is the output parameter of the model. In order to improve the accuracy of the LS-SVM results, the KF technique is used to update the tool wear estimated results of LS-SVM-based model, which is called the LS-KF model, according to the measured tool wear values. Experiment work is performed on machining center for cemented carbide ball-end cutter cutting stainless steel. Those two models (LS-SVM model and LS-KF model) are applied to the actual milling machining to verify their performance. Results show that predicted tool wear based on the proposed LS-KF model has more precision than that of LS-SVM model.

Wear optimization of titanium alloy cutter milled with microtextured ball-end milling cutter

Aimed at solving the problems of tool wear and poor surface quality in milling a Ti alloy with a ball-end milling cutter, a method of applying a microtexture to a tool rake face to reduce tool wear is proposed in this article. By comparing the wear morphology of microtextured tools with that of nontextured tools after milling with the same stroke, the antifriction and antiwear mechanism of the micropit texture and the failure mode of the ball-end milling cutter are analyzed. The results of a simulation and orthogonal experiments reveal that with the increase of the micropit parameters, the wear value of the rake and rear faces first decreases and then increases. The effects of the micropit parameters on the wear value of the ball-end milling cutter decrease in the following order: distance from edge > diameter > spacing > depth. Finally, by using a multi-objective optimization method, the optimal solution set of the texture parameters of micropits is obtained by evaluating the wear values of the rake and rear faces of the ball-end milling cutters: 46 μm < diameter < 50 μm, 23 μm < depth < 26 μm, 109 μm < spacing < 112 μm, and 85 μm < distance from edge < 89 μm.

Method of Five-axis Tool Radius Compensation Based on Post-processor

In order to solve the problem of tool radius compensation in five-axis machining for the CNC systems without the function of five-axis tool radius compensation, a method of five-axis tool radius compensation based on post-processor is proposed. First, the basic principle of five-axis tool radius compensation is investigated. For three types of cutters(i.e. ball-end cutter, flat-end cutter, and torus cutter), tool radius compensation direction and vector equation of compensated cutter location(CL) point are derived, respectively. Second, a five-axis CNC machine tool with rotary head and table is used as an example. In terms of the relation equation between CL data and machine control data and vector equation of compensated CL point, a relation equation between compensated CL data and machine control data will be obtained. Then, a post-processing software with the function of five-axis tool radius compensation is developed using Visual C++ 6.0. And the post-processing software not only generates the compensated CNC program directly, but also generates the CNC program with macro variables of tool radius compensation. Finally, an aero blade surface is machined, and the machining process is simulated by using VERICUT software. Simulated results verify the correctness and effectiveness of the proposed method. Accordingly, the proposed method can easily implement the function of tool radius compensation for the CNC systems without the function of five-axis tool radius compensation, and avoid the complicated process that when the cutter radius changes, the programmer must return to CAM system to generate new tool paths and post-process CL data again. Further, the proposed method can shorten the total machining time of parts and enhance the reusability of CNC program, and will be widely applied in practice.

Experimental Study on Wear and Fracture of Ball-End Milling Cutter in High Speed Machining Stainless Steel 0Cr13Ni4Mo

An experimental study on wear and fracture of ball-end milling cutter in high speed machining martensitic stainless steel 0Cr13Ni4Mo is studied in this work. Through the SEM micrographs and energy spectrum analysis of the wear pattern of the rake face, severe coating spalling is found near the main cutting edge. Fracture is seen on the entire cutting edge, in which micro-chipping occurs on the both ends of the cutting edge, and chipping occurs in the middle of the cutting edge and is the conchoidal spalling on the rake face. Combined with the high-speed photography of the milling process, the fracture area is consistent with the chip-adhesion area.

APPLICATION OF HOMOGENOUS TRANSFORMATION MATRIX TO THE MODELING OF A BALL-END CUTTER

This paper presents a comprehensive and straightforward method for the mathematical modeling of a generic ball-end cutter. In the proposed approach, a mathematical model of the rake surface is developed based on a normal helix cutting edge geometric model. A mathematical model of the flank surface is then derived based on the assumption of a constant clearance angle. The proposed model is applicable to a wide range of ball-end cutters. As a result, it provides an ideal basis for the generation of the NC equations required to machine ball-end cutters on a 6-axis CNC grinding machine.

Efficient Surface Segmentation Algorithm for 3-Axis Machining with a Ball-End Cutter

Surface machining is one of the key problems in aircraft part-manufacturing. This paper presents a novel approach to solve the surface segmentation issue under 3-axis machining mode with a certain processing coordinate system, according to the workability-based ridge extracting algorithm proposed here. Firstly, basic principles such as ridge point and ridge of a surface are explained in detail. Secondly, the workability-based ridge extracting algorithm is put forward to better slice the surface. Finally, the proposed workability-based ridge extracting methodology is tested on a 3D model and its performance reveals that the method described here is effective in terms of time and feasibility. The work presented here has reached a basis for feature recognition during computer aided manufacturing process when fabricating aircraft structural parts.

On-line tool wear measurement for ball-end milling cutter based on machine vision

Cutting tool wear is known to affect tool life, surface quality and production time. In this paper, a new on-line tool wear measuring algorithm is proposed to acquire tool wear using machine vision in order to establish on-line tool wear monitoring model for assessing degree of wear and remaining useful tool life. The algorithm first adopts machine vision to acquire tool wear images from CCD camera on-line for ball-end cutter. Tool tip points are determined and wear detection areas are optimized within captured tool wear images. Tool wear images before machining and in machining process are captured to compare the corresponding image column for judging whether this image column has emerged wear. Then the initial detection of wear edge points with pixel accuracy is given to scan pixel columns within the constructed wear detection areas in vertical direction. The exact detection algorithm of wear edge points with sub-pixel accuracy is proposed to increase the precision of detected wear edge points. The tool wear can be computed based on the detected wear edge points. Experimental work and validation of the established on-line tool wear measurement method are performed in a five-axis milling center by using stainless steel 1Cr18Ni9Ti and ball-end cutter of cemented carbide. The obtained measurement results by using the proposed method are compared with those gotten by measuring directly with microscope. The proposed method is shown to be reliable and effective for on-line tool wear measurement.

Research on Character of Physical Field Distribution in High Speed Ball-End Milling Hardened Steel

In order to mend cutting instability of ball-end milling cutter caused by the changes of cutting loads in high speed milling hardened steel, we perform the modal analysis and heat-force coupling field analysis of cutter, carry out the experiment of high speed milling hardened steel, investigate the character and effect factor of physical field distribution in high speed ball-end milling hardened steel, and propose the method about the match of diameter and overhang for depressing cutter vibration. Results indicate that the decrease in the ratio of overhang to diameter can transform the first modal shape of cutter from bending modal shape into torsion modal shape. The diameter of cutter is from 30mm to 20mm, the overhang of cutter is from 125mm to 90mm, heat-force coupling field distribution changes slightly, resonance of cutter does not occur, and efficiency in machining hardened steel can be improved effectively by higher cutting speed.

Analysis on Milling Force Based on AdvantEdge FEM

Aiming at NC milling processing simulation problem, a ball-end cutter milling force model is established, the numerical simulation analysis of aluminum alloy AL2024 milling process is conducted by using the finite element analysis software AdvantEdge FEM. Focus on the Milling force simulation, the size of the milling force is obtained by simulating calculation. Using the same cutting parameters for milling experiment, the results show that simulation analysis of the cutting force values are in good agreement with the experimental results，the milling force model prior established is correct. The research laid a foundation for the perfect CNC milling simulation system.

Mathematical Modeling of Ball-End Cutter

The ball-end cutter plays an important role in machining free-form surfaces due to its adaptability to a surface. It is widely used in aerospace, automobile, and die/mode industries. Thus, the demand for higher cutting performance and lower cost of the ball-end cutter has been increasingly focused. In this paper, based on normal helix cutting edge geometric model, the cone wheel, which was used to grind the rake and flank face of ball-end cutter, was designed. Then, we use homogenous coordinate transformation to derive for the ball-end cutter and establish the mathematical model for grinding this type cutter in terms of grinding parameters. Finally, the cutting angles of ball-end cutter were discussed.

Reliability-Based Sensitivity Analysis for Machining Precision by Saddle-Point Approximation

Based on the saddle-point approximation theory, the reliability sensitivity formula is derived systematically. Then, combining the reliability theory with the sensitivity analysis method, the reliability-based sensitivity of machining precision for ball-end milling cutter is analyzed. Based on the premise that the probability distribution of random parameters is known, firstly, the saddle-point approximation theory is employed to solve the reliability of machining precision for ball-end milling cutter and, as a result, the saddle-point approximation method is proved accurate with higher speed in comparison with the Monte-Carlo method. Secondly, the reliability-based sensitivity is calculated. Finally, the effect of changes in machining parameters on the reliability of machining precision is analyzed.

Optimal tool orientation control for 5-axis CNC milling with ball-end cutters

When a ball-end milling tool cuts a given path on a smooth surface, it is desirable to maintain a fixed angle ψ between the tool axis a and the local surface normal n at each point, to ensure a constant speed of the tool cutting edge against the surface. This means that the tool axis a must lie on a cone of angle ψ about the surface normal n at each point, but its azimuthal position on this cone remains indeterminate. To resolve this indeterminacy, while minimizing actuation of the rotary axes that orient the workpiece relative to the tool, the component of a in the surface tangent plane is specified through the parallel transport of a given initial state along the path. This amounts to the integration of coupled first-order differential equations that involve the Christoffel symbols for the given surface. Alternatively, the tangent plane component of the tool axis a is shown to be rotation-minimizing with respect to the surface normal n, and its orientation relative to the Darboux frame along the tool path can be determined by integrating the geodesic curvature along that path. The method is illustrated by closed-form solutions for simple analytic surfaces, and numerical integration using an object-oriented software implementation for free-form surfaces. The real-time implementation of such rotation-minimizing 5-axis tool motions for free-form surfaces is well within the scope of modern CNC systems.

Power Series Solution for Isoscallop Tool Path Generation on Free-form Surface with Ball-end Cutter

In this paper we propose a method to compute symbolically a curve of constant scallop height on the surface swept by a ball-end cutter when it traces a free-form cutter-contact curve on a free-form surface. We give explicit formulas for power series solutions to the curve of constant scallop height and the next cutter-contact curve, when the initial cutter-contact curve is given. To make the symbolic results useful in practice, we propose a method to approximate the solutions unilaterally in the parametric plane by piecewise Chebyshev polynomials and exponential functions.