Tool Path Planning Research Articles

Research on the Optimized Tool-Path Planning of Computer Controlled Optical Surfacing

Computer controlled optical surfacing (CCOS) is widely used in aspheric optical lenses fabrication because of their high convergence rate on surface based on deterministic removal processes since 1963. As an important part of CCOS techniques, reasonable tool-path would increase the polishing speed, decrease the processing time and then improve the efficiency of polishing. Optimized policy combined with improved Prim algorithm is presented in this paper based on the study of the characteristic of aspheric polishing and the tool-paths in common use. The simulated results show that the length of tool-path is reduced so as to decrease the processing time and increase the working efficiency.

Tool path planning based on endpoint build-in optimization in rapid prototyping

Filling defects, which appear on the tool path ends as the existence of the control precision error of enabling components (laser, nozzle) and movement acceleration and deceleration of moving components, cause serious problems in appearance quality of parts in a number of welding-based rapid prototyping processes such as plasma welding, laser welding, and fused deposition modeling. This paper presents a novel tool path planning algorithm based on endpoint build-in optimization, moving the two path endpoints with filling defects from the part surface into the internal region. Experiments in fused deposition modeling processes show that the algorithm effectively addresses this issue, and is reliable and efficient.

Minimization of the kinematics error for five-axis machining

Kinematics of a particular five-axis milling machine can drastically change the machining accuracy. Therefore, the reduction of the kinematics error is an important problem associated with the tool path planning. Our new optimization method employs a closed form of the kinematics error represented as a function of the positions of the cutter contact points. The closed form is derived from the inverse kinematics associated with a particular five-axis machine and obtained through automatic symbolic calculations. The second component of the algorithm is the optimal setup of the part surface on the mounting table employed in an iterative loop with the generation of the cutter contact points. For a prescribed tolerance the proposed optimization allows for substantial reduction in the number of required cutter contact points. The reduction can be significant and may amount to long hours of machining if the machining time at the programmed feed is less than the sampling time of the controller. In turn, when the number of cutter location points is fixed, the error can be substantially reduced. However, this refers to commanded error wherein the dynamics of machine tool are not taken into account. We present an analysis, systematic numerical experiments and results of real cutting (ball nose and flat-end cutters) as an evidence of the efficiency and the accuracy increase produced by the proposed method. We also evaluate the relative contributions of the setup and the point optimization. The method is shown to work with advanced tool path generation techniques proposed earlier such as the adaptive space filling curves. The numerical and machining experiments demonstrate that the proposed procedure outperforms tool paths based on the equi-arclength principle and paths generated by MasterCam 9.

Tool Path Planning and NC Generation of Tilted Plane Machining Features for Five-Axis Machining

Designs of free-form surface products are becoming increasingly complex. In traditional three-axis machine tool machining, errors that are caused by repetitive positioning and the costs of fixture jig design and manufacturing are critical. Since multi-axis machining provides two more rotational degrees of freedom than a three-axis machine tool, the former can solve these problems, and has therefore become the trend of precision cutting. As multi-axis machined parts often have holes and grooves on the tilted plane, this work proposes a method for machining tilted working plane features and for NC generation on a five-axis machine. The developed module can provide common geometric features, allowing the user to alter the machining feature and sequence on the tilted plane quickly using the parent-child relationship in a tree diagram, and plan the tool path. The postprocessor module developed in this paper can transform the tool path into an NC program required for machining. Finally, solid cutting simulation software is utilized to confirm the feasibility and correctness of the tool path and NC data of the tilted plane machining feature.

Contour Offset Approach to Generate Tool Path for Polyhedral Surfaces Machining

Polyhedral surfaces are used as representation model for CAM and process planning purposes because of its simplicity for data exchange and geometric computation. However, there is few tool path planning strategies for such surfaces but the iso-plane method. In this paper, contour parallel path are generated for three-axis ball-end milling. This tool path is based on a novel algorithm for offsetting curves on polyhedral surfaces presented in this paper. It reduces the task of removing complex interfering of offset curve from 3D surface to 2D plane by flattening mesh surface, and avoids costly 3D Boolean set operations and expensive distance calculation. This results in an efficient tool-path generation. Empirical examples illustrate the feasibility the proposed method.

Stiffness optimization of a novel reconfigurable parallel kinematic manipulator

SUMMARYThis paper proposes a novel design of a reconfigurable parallel kinematic manipulator used for a machine tool. After investigating the displacement and inverse kinematics of the proposed manipulator, it is found that the parasitic motions along x-, y-, and θz-axes can be eliminated. The system stiffness of the parallel manipulator is conducted. In order to locate the highest system stiffness, single and multiobjective optimizations are performed in terms of rotation angles in x- and y-axes and translation displacement in z-axis. Finally, a case study of tool path planning is presented to demonstrate the application of stiffness mapping. Through this integrated design synthesis process, the system stiffness optimization is conducted with Genetic Algorithms. By optimizing the design variables including end-effector size, base platform size, the distance between base platform and middle moving platform, and the length of the active links, the system stiffness of the proposed parallel kinematic manipulator has been greatly improved.

Particle swarm optimisation (PSO)-based tool path planning for 5-axis flank milling accelerated by graphics processing unit (GPU)

Multi-axis machining offers higher machining efficiency and superior shaping capability compared to 3-axis machining. Machining error control is a critical issue in 5-axis flank milling of complex geometries and there is still a lack of solutions. Previous studies have shown that optimisation-based tool path planning is a feasible approach to reduction of machining error. However, the error estimation is time-consuming in the optimisation process, thus limiting the practicality of this approach. In this work, we apply graphics processing unit (GPU) computing technology to solve this problem. A particle swarm optimisation (PSO)-based optimisation scheme is developed to generate a series of cutter locations (CLs) that produce a minimised error on the machined surface. The error amount induced by each CL is simultaneously calculated by the parallel processing units of GPU. The PSO search process driven by the aggregated result is effectively accelerated. Test results show that our approach outperforms previous optimisation methods in both solution quality and computation efficiency. This work demonstrates a novel application of GPU on Computer Aided Manufacturing/Computer Numerical Control.

A functionally gradient variational porosity architecture for hollowed scaffolds fabrication

This paper presents a novel continuous tool-path planning methodology for hollowed scaffold fabrication in tissue engineering. A new functionally gradient porous architecture is proposed with a continuous material deposition planning scheme. A controllable variational pore size and hence the porosity have been achieved with a combination of two geometrically oriented consecutive layers. The desired porosity has been achieved with consecutive layers by geometrically partitioning each layer into sub-regions based on the area and the tissue scaffold design constraints. A continuous, interconnected and optimized tool-path for layers has been generated for a three-dimensional biomaterial deposition/printing process. A zigzag pattern tool-path has been proposed for an accumulated sub-region layer, and a concentric spiral-like optimal tool-path pattern has been generated for the successive layer to ensure continuity along the structure. Three-dimensional layers, formed by the proposed tool-path plan, vary the pore size and the porosity based on the biological and mechanical requirements. Several examples demonstrate the proposed methodology along with illustrative results. Also a comparative study between the proposed design and conventional Cartesian coordinate scaffolds has been performed. The results demonstrate a significant reduction in design error with the proposed method. Moreover, sample examples have been fabricated using a micro-nozzle biomaterial deposition system, and characterized for validation.

Coverage based tool-path planning for automated polishing using contact mechanics theory

Presented in this paper is a tool-path planning method for automated polishing. This work is an integral part of research program on automated polishing/deburring being carried out at Ryerson University. Whereas tool-path planning for machining is treated as a geometry problem, it is shown here that tool-path planning for polishing should be treated as a contact mechanics problem because of contact action between the polishing tool and the part. To develop this method, contact mechanics is applied for contact area modeling and analysis. Once the contact area is determined for multiple points along the given polishing path, a Contact Area Map ( CAM) is established and used to show the coverage area during polishing. This map is then used to plan polishing paths that ensures a complete coverage for polishing. Simulation has been conducted to show the effectiveness of this new tool-path method.

Study of Sphere NC Sheet Metal Incremental Forming

The principle of NC incremental sheet metal forming as well as the process planning, experiment of sphere forming are presented. Because the deformation of sheet metal only occurs around the tool head and the deformed region is subjected to shear deformation and thins, and surface area increases. Sheet metal forming stepwise is to lead to the whole sheet metal deformation. According to sine law, a sphere can’t be formed by NC incremental sheet metal forming process in a single process, rather, it must be formed in multi processes. Thus, the two time path process method is presented to form the sphere, and the experiment is made to verify it. A sphere can be formed from a sheet metal in NC incremental forming process by choosing appropriate tool-path planning. The fracture in the forming component can be avoided by these methods. A sphere of uniform wall-thickness can be formed from the truncated cone by NC incremental forming process.

Mechanistic Model Based on the Actual Removal Volume during Simultaneous Five-Axis Milling

In this paper we present a novel mechanistic model of cutting process of the cylindrical tool by using the actual removal volume per tooth via NC simulation. The simulation kernel enables “virtually” cutting the workpiece in milling process per NC code, as well as calculating the removal volume per tooth which leads to predict the actual cutting force during simultaneous five-axis machining. Combined with the material removal simulation, the advanced mechanistic process model, which can enable the prediction of the cutting force and adjust the trajectory velocity of the cylindrical tools undergoing five-axis movement, is presented by applying the line integral along the cutting edge and taking the rake angle and cutting edge roundness into consideration. The novel methodology to adjust the cutting force by prevailing cutting tools undergoing multi-axis motion is to be validated by experiment and integrated into tool path planning systems.

Tool Path Planning of the Micro Cowled Integral Impeller

The micro crowled integral impeller is one of the key parts of aeroengine. It is difficult to machine for its complex structure and small dimension. In this paper, the tool path planning scheme of micro crowled integral impeller is researched, which lays foundation for the numerical control machining of the part. To begin with, considering the feature of impeller’s structure, a kind of processing route is proposed and the processing regions are divided, which satisfy the demand of accuracy and efficiency. Then, the tool path planning scheme of the impeller is put forward, which is regular and is more suitable for a large-diameter tool to fulfill the machining process. Finally, machining simulation is carried out to prove the feasibility and correctness of the proposed path planning scheme.

Efficient tool path planning for 5-axis flank milling of ruled surfaces using ant colony system algorithms

Five-axis CNC flank milling has recently received much attention in industry. The flank milling operation is efficient in shaping ruled geometry, but introduces a challenging task in machining error control. Previous work proposed a dynamic-programming based scheme for generating optimal tool path by minimising the machining error. However, to compute the tool path takes a considerable amount of time. This paper presents a new scheme using meta-heuristics, ant colony system (ACS), for tool path planning in 5-axis flank milling, with a focus on improving the computation efficiency. The path planning problem is first formulated as mapping two boundary curves of a ruled surface. An ACS-based optimisation algorithm is then applied to search for the mapping that minimises the machining error. The solution is nearly as good as using dynamic programming but takes only half of the computational time. The results from machining experiment and 3D measurement validate the effectiveness of the proposed scheme.

A Method of Machining Region Planning for Tyre Tread Mold Machining

To satisfy the manufacturing requirement of tyre tread pattern mold, the problem of machining region planning in the computer aided manufacturing of tyre mold is introduced. And it is analyzed that the core technology is the definition of inner and outer contours for machining region planning and tool-path planning. According to the defect of traditional constructed way of machining region, an auto recognition method of inner and outer contour is studied based on the inclusive test method.The detail step of the method is illustrated.Thinking about the special condition of the method, corresponding strategy is given. This method is applied in the computer aided manufactuing of tyre tread mold, by which machining region planning can be solved effectively.

A Modified Isoscallop Height Toolpath Planning Method for Generating Smooth Paths Based on Curve Fitting Method

Isoscallop height toolpath planning method is a high-efficient way to generate toolpaths. However, for some sculptured surfaces, the toolpaths generated via this method may be not smooth, e.g. the cutting direction may alter sharply which badly affecting the machining surface quality. If the curvature of toolpaths can be restricted, paths will be smooth and surface quality can be guaranteed. On the other hand, the machining efficiency may decrease comparing with toolpaths generated via Isoscallop height method. To balance efficiency and surface quality, a modified isoscallop height toolpath planning method based on curve fitting is proposed in this paper. Toolpaths generated via the new method can keep smooth and the efficiency is as high as possible under the restriction of the curvature set by users.

A Continuous Multi-material Toolpath Planning for Tissue Scaffolds with Hollowed Features

A Continuous Multi-material Toolpath Planning for Tissue Scaffolds with Hollowed Features

A Customized Smart CAM System for Digital Dentistry

AbstractThis paper presents an automated system for NC tool-path planning and generation of digital dental restoration. The process planning of an automated system has to do with well-ordered approaches, and accurate, efficient manufacture of work-pieces or parts, from initial to finished stages. Traditionally, dental restoration making is a totally manual and labor-intensive work, and the computer aided design (CAD) /computer aided manufacturing (CAM) technology has rarely been utilized. In recent years, however, with the advancement of intra-oral scanning technology, more and more CAD/CAM technology is being applied to the design and production of dental restorations. Since the operators are dental technicians who are mostly unfamiliar with CAD/CAM, it is important to have a customized and highly automated dental CAD/CAM system for the digital dental industry. General-purpose CAM system cannot be used in this case because long hours of tool-path programming and editing are required. In order to reduce p...

A Continuous Multi-material Toolpath Planning for Tissue Scaffolds with Hollowed Features

Computer-Aided Design and Applications is an international journal on the applications of CAD and CAM. It publishes papers in the general domain of CAD plus in emerging fields like bio-CAD, nano-CAD, soft-CAD, garment-CAD, PLM, PDM, CAD data mining, CAD and the internet, CAD education, genetic algorithms and CAD engines. The journal is aimed at all developers and users of CAD technology to ptovide CAD solutions for various stages of design and manufacturing. The journal publishes all about Computer-Aided Design and Computer-Aided technologies.

Researches on Burr Formation in Milling Al-Alloy

Burr formation is a bottleneck of the production line and deteriorates the automation integrity. To this question, investigations were carried out in this paper on the burr formation in milling aluminum alloy (Al-alloy), in order to enhance productivity and workpiece quality by active process control. Milling burr formation were predicted and minimized for the sake of rough machining and finishing operation, using strategies of tool path planning, processing parameter optimization as well as workpiece rigidity strengthening. The conclusions reached in this paper are useful in practice to realize burr-free Al-alloy milling for manufacturing automation.

Efficient Tool Path Planning for Machining an Impeller with a 5-Axis NC Machine

This paper presents an efficient tool path plan for machining the impeller with a 5-axis numerically controlled machine. A method of assigning key tool orientations is reported and B-spline interpolation is used to produce smooth and interference-free tool orientation. The final tool paths generated by the proposed method are verified by using the cutting simulation function. A machining experiment is performed on a Mikron machine tool. Experimental results show that the present method is feasible and can produce interference-free tool path.