Nonparametric Tool Path Compensation for Machining Flexible Parts

Author(s):  
Waku Hatakeyama ◽  
Cong Wang ◽  
Lu Lu

This paper discusses the compensation of tool paths for machining flexible parts. Despite various research published on the topic, machining in practice nowadays remains limited to tool path planning based on only the geometric models of the parts and tools. This is mainly because that tool path compensation methods usually require accurate physical information of the systems and rely on analytical or finite element simulations, which are often not available to the end-users. In regards to this problem, this paper presents data-oriented nonparametric learning methods that require solely the geometric measurements of the trial machined contour(s). The physical parameters of the parts and tools as well as simulations of the machining process are not required. Two algorithms are developed based on Gaussian Process Regression and Artificial Neural Network respectively. Experimental tests are conducted. A plan of further improving the results using an auxiliary real-time vision sensor is also discussed.

Author(s):  
Adam Jacso ◽  
Tibor Szalay ◽  
Juan Carlos Jauregui ◽  
Juvenal Rodriguez Resendiz

Many applications are available for the syntactic and semantic verification of NC milling tool paths in simulation environments. However, these solutions – similar to the conventional tool path generation methods – are generally based on geometric considerations, and for that reason they cannot address varying cutting conditions. This paper introduces a new application of a simulation algorithm that is capable of producing all the necessary geometric information about the machining process in question for the purpose of further technological analysis. For performing such an analysis, an image space-based NC simulation algorithm is recommended, since in the case of complex tool paths it is impossible to provide an analytical description of the process of material removal. The information obtained from the simulation can be used not only for simple analyses, but also for optimisation purposes with a view to increasing machining efficiency.


Author(s):  
Dun Lu ◽  
Jun Liu ◽  
Wanhua Zhao ◽  
Bingheng Lu ◽  
Diaodiao Wu ◽  
...  

Blades are essential parts used in thermal and nuclear power generation. Its machining precision is a vital factor that influences the efficiency and life of those industries. Blades are thin-walled parts, which could easily deform under cutting forces, and hence deteriorate the machining precision. In our previous work, a milling process with twin tool for blade is proposed, in which two tools are assigned to machine the basin and dorsal surfaces simultaneously. It is expected that the cutting forces acted on the basin and dorsal surfaces can be counteracted to reduce the deformation of the blade. In this study, a method of twin-tool paths generation is developed. The tool center points and tool axis vectors are generated with consideration of the cutting forces balance, the machine tool kinematics, the surface geometric precision, and the same number of tool paths on basin and dorsal surfaces. Virtual machining, finite element analysis, and trial cutting are carried out and verified that the method which is used for generating the twin-tool paths is successful. The basin and dorsal surfaces have the same number of tool paths and tool contact point coordinates, which guarantees that the two surfaces can be completely machined and can be machined and finished simultaneously. Furthermore, the cutting forces acted on the basin and dorsal surfaces can achieve the balance along the twin-tool paths. Therefore, the deformation of a blade caused by cutting force is obviously reduced compared with a conventional machining process with a single tool.


Author(s):  
Xiaohong Zhu ◽  
Richard F. Riesenfeld

Abstract Today’s part geometries are becoming ever more complex and require more accurate tool path to manufacture. Machining process efficiency is also a major consideration for designers as well as manufacturing engineers. Although the current advanced CAD/CAM systems have greatly improved the efficiency and accuracy of machining with the introduction of Numerically–Controlled machining, excessive material may still be left on the finished part due to machining constraints, including the inaccessibility of the designed part geometry with respect the cutter, machine motion constraints like ramp angles, specific cutting patterns, etc. Polishing operations such as grinding and hand finishing are quite time consuming and expensive, and may damage the surface of the part or introduce inaccuracies because of human errors. While most of the existing machining approaches attempt to reduce such excessive restmaterials by modifying NC tool paths, none of them is satisfactory. They can be time–consuming, error prone, computationally intensive, too complicated to implement, and limited to certain problem domains. A compensating cleanup tool path will be developed in this research to automatically remove these excessive material from the finish part. This method greatly reduces the burden of hand finishing and polishing, and also reduces the error and complexities introduced in manually generating cleanup tool paths in the shop floor. More important, the tool path generated by this method will reduce the machining time, and increase tool life compared with optimized tool path which left no excessive material behind.


2014 ◽  
Vol 875-877 ◽  
pp. 896-900
Author(s):  
Xiao Fei Bu ◽  
Hu Lin ◽  
Long Chen

High finishing machining tool path generation methods are usually adopted for five-axis computer numerically controlled machining of sculptured surface parts. The quality of the high finishing machining has an important effect on that of the surface. In this paper, a high finishing machining tool path generation method is introduced to generate an optimal tool path. The initial tool path is firstly created based on the constant scallop height, then the derived tool paths are generated as a kind of the diagonal curve by the initial tool path, and at last, the tool path smoothing algorithm is applied to the generated tool path. This path algorithm can ensure higher level of smooth of the surface been machined. Finally, the results of simulation and experiment of the machining process are given to verify the smooth and applicability of the proposed method.


2015 ◽  
Vol 3 (2) ◽  
pp. 151-160 ◽  
Author(s):  
Xun Gong ◽  
Hsi-Yung Feng

Abstract Cutter-workpiece engagement (CWE) is the instantaneous contact geometry between the cutter and the in-process workpiece during machining. It plays an important role in machining process simulation and directly affects the calculation of the predicted cutting forces and torques. The difficulty and challenge of CWE determination come from the complexity due to the changing geometry of in-process workpiece and the curved tool path of cutter movement, especially for multi-axis milling. This paper presents a new method to determine the CWE for general milling processes. To fulfill the requirement of generality, which means for any cutter type, any in-process workpiece shape, and any tool path even with self-intersections, all the associated geometries are to be modeled as triangle meshes. The involved triangle-to-triangle intersection calculations are carried out by an effective method in order to realize the multiple subtraction Boolean operations between the tool and the workpiece mesh models and to determine the CWE. The presented method has been validated by a series of case studies of increasing machining complexity to demonstrate its applicability to general milling processes. Highlights A new method to determine cutter-workpiece engagement geometry in milling. Applicable to general milling processes: all cutter types, in-process workpiece shapes and tool paths containing even self-intersections. Results validated by a series of case studies of increasing machining complexity.


Author(s):  
Eric Wang ◽  
Il-Kyu Hwang ◽  
Yong Se Kim

Abstract We describe an automatic machining tool path generation method that combines local tool path planning for machining features with global tool path planning. From the solid model and the tolerance specifications of the part, machining features are automatically recognized, and geometry-based precedence relations are obtained between these features. From this information, the machining sequence, tool selections, and machining conditions are determined. Machining tool paths are then generated automatically for each setup, combining local and global tool paths. Local tool paths to machine each feature are generated using successive offsetting operations. Global tool paths between features are generated incrementally by searching the adjacency graph of feature free spaces, which represents the current free space of the part. Feature free spaces are obtained by expanding the machining features through their fictitious faces. The start and end positions for the local tool paths of each feature are selected based on a heuristic method to minimize the cost of each segment of the global tool path. This automatic tool path generation method is currently being developed as part of a comprehensive machining process planning system.


Author(s):  
A Petrovic ◽  
L Lukic ◽  
S Ivanovic ◽  
A Pavlovic

Peripheral pocket or contour milling in wood machining, using flat end milling tool, can be performed with different tool paths. Technology designers of multi axis CNC wood machining use their experience and intuition to choose some of the options offered by CAM systems that determine the final shape of tool path, thus the generated tool path largely depend on individual judgment. Minimum cutting force, maximum dynamic stability of the process and minimum tool wear are achieved, or some other technological requirements are met, by using optimal tool path. Tool path optimisation is based on analysis of possible tool paths and determination of cutting parameters which are dependable of chosen tool path and are affecting the main wood processing factors. Axial and radial depth of cut, engagement angle, feed and feed rate profile are identified as key parameters dependable of tool path, and their values and variations along the tool path influence the cutting speed, tool wear and cutting force. Knowledge of values and changes of those key machining parameters along the tool path is necessary for simulation and monitoring of the main cutting factors during the wood machining process. NC code transformation methodology and generation of tool path parameters necessary for calculating all elements needed for tool movement simulation from given NC programs are shown. Blank and tool mathematical description are used with tool movement information for simulation of wood machining process. Simulation of cutting parameters and their variation along the tool path, presented in this paper, can be used as bases for development of methodology for choosing the most adequate tool path for wood machining of given contour considering minimum cutting force and cutting force variation, minimum tool wear, maximum productivity or some other criteria.


Author(s):  
F Abrari ◽  
M A Elbestawi ◽  
A D Spence

Solid modellers are now well established for computer aided design of mechanical parts. Machining applications, however, remain limited to geometric tool path planning. The physical aspects of the process are largely ignored. Success in actual machining, however, depends on consideration of cutting forces, torques, part and tool deflection, chatter, tool breakage and wear. This paper reports research progress towards a comprehensive simulation of the physical machining process of thin flexible parts. The system is based on extensions to a commercially available solid modeller. Cutting tool location data (CL-DATA) files along with an initial solid model of the workpiece are inputs. Each tool motion is segmented into short steps along the path and angular increments of spindle rotation. At each simulation step, immersion of the cutting tool teeth with the part is calculated. This information is then used by a machining process model to calculate cutting forces and tool/workpiece deflection. Up to five-axis motion is supported using a sweep representation of the tool swept volume. Flexible tools are modelled as cantilevers; flexible parts are created as solid models, are meshed and are dynamically solved using finite element analysis. The mesh is updated as material is machined away from the part.


2021 ◽  
Vol 11 (9) ◽  
pp. 4055
Author(s):  
Mahdi S. Alajmi ◽  
Abdullah M. Almeshal

Machining process data can be utilized to predict cutting force and optimize process parameters. Cutting force is an essential parameter that has a significant impact on the metal turning process. In this study, a cutting force prediction model for turning AISI 4340 alloy steel was developed using Gaussian process regression (GPR), support vector machines (SVM), and artificial neural network (ANN) methods. The GPR simulations demonstrated a reliable prediction of surface roughness for the dry turning method with R2 = 0.9843, MAPE = 5.12%, and RMSE = 1.86%. Performance comparisons between GPR, SVM, and ANN show that GPR is an effective method that can ensure high predictive accuracy of the cutting force in the turning of AISI 4340.


2010 ◽  
Vol 154-155 ◽  
pp. 310-313
Author(s):  
Xue Feng Bi ◽  
Jin Sheng Wang ◽  
Jia Shun Shi ◽  
Ya Dong Gong

Micromold manufacturing technology is very important for the mass production of micro parts. In this paper, modeling of micromold is established in 3D software firstly. The 3D modeling is input into machining simulation software Master CAM to simulate machining process. The machining parameters and cutting tool path are optimized in machining simulation. Machining G code of micromold obtained from post-process program of Master CAM is input into HMI system of Micro Machine Tool (MMT), and hence the micromold will be machined precisely in MMT.


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