scholarly journals Precision Sculptured Surface CNC Machining Using Cutter Location Data

2016 ◽  
Vol 686 ◽  
pp. 224-233
Author(s):  
Nikolaos A. Fountas ◽  
Nikolaos M. Vaxevanidis ◽  
Constantinos I. Stergiou ◽  
Redha Benhadj-Djilali
Keyword(s):  
Tool Path ◽  
Low Cost ◽  
Cnc Machining ◽  
Sculptured Surface ◽  
Sculptured Surfaces ◽  
Rough Machining ◽  
Machining Error ◽  
Location Data ◽  
Tool Paths ◽  
Cutter Location Data

Industrial parts with sculptured surfaces are typically, manufactured with the use of CNC machining technology and CAM software to generate surface tool paths. To assess tool paths computed for 3-and 5-axis machining, the machining error is evaluated in advance referring to the parameter controlling the linearization of high-order curves, as well as the scallop yielded as a function of radial cutting engagement parameter. The two parameters responsible for the machining error are modeled and corresponding cutter location data for tool paths are utilized to compare actual trajectories with theoretical curves on a sculptured surface assessing thus the deviation when virtual tools are employed to maintain low cost; whilst ensuring high precision cutting. This operation is supported by applying a flexible automation code capable of computing the tool path; extracting its CL data; importing them to the CAD part and finally projecting them onto the part’s surface. For a given tolerance, heights from projected instances are computed for tool paths created by changing the parameters under a cutting strategy, towards the identification of the optimum tool path. To represent a global solution rough machining is also discussed prior to finish machining where the new proposals are mainly applied.

A Generic, Geometric Approach to Accurate Machining-Error Predictions for 3-Axis CNC Milling of Sculptured Surface Parts: Part II — Applications and Analysis

2006 ◽  
Author(s):  
Zezhong C. Chen ◽  
Wei Cai
Keyword(s):  
Tool Path ◽  
Geometric Approach ◽  
Sculptured Surface ◽  
Cnc Milling ◽  
Sculptured Surfaces ◽  
Machining Error ◽  
Tool Paths ◽  
Machining Errors ◽  
Tool Surface ◽  
Cam Software

As sculptured surfaces are widely used in mechanical design, machining sculptured surface parts accurately is highly demanded in industry; however, it is quite challenging to meet their demand. Due to the geometric complexity of these surfaces, the tool-surface geometric mismatch always causes machining errors when the tool cuts along the tool paths. To prevent surface gouging, where the machining error is greater than the part tolerance, state-of-the-art CAM software usually determines cutter contact (CC) points on the tool paths first, and then simulates the machining to check the errors caused by this tool-surface mismatch. If surface gouging occurs, the CC points are adjusted using the CAM software. But this established method is quite time consuming and sometimes ineffective. To overcome these problems, a new system, based on the accurate predictions of machining errors, is proposed in this research paper for the optimization of CC points on the tool paths. First, two established CC point generation methods, the chordal deviation method and the circular arc approximation method, are introduced; and their limitations are addressed. Second, a sensitivity study of the machining errors with respect to the cutting tools is conducted. Then a system implementing the generic, geometric approach to accurate machining-error predictions is proposed to optimize CC points on the tool paths. Finally, this CC point optimization system is applied to two practical parts to demonstrate its advantages over the two established methods. This proposed work provides a profound understanding of the machining errors caused by the tool-surface mismatch and contributes to tool path planning for 3-axis CNC milling of sculptured surface parts.

A Generic, Geometric Approach to Accurate Machining-Error Predictions for 3-Axis CNC Milling of Sculptured Surface Parts: Part I — Modeling and Formulation

2006 ◽  
Author(s):  
Zezhong C. Chen ◽  
Wei Cai
Keyword(s):  
Tool Path ◽  
Cutting Tool ◽  
Geometric Model ◽  
Research Work ◽  
Geometric Approach ◽  
Cnc Machining ◽  
Sculptured Surface ◽  
Machining Error ◽  
Machining Errors ◽  
Tool Surface

In CNC machining, machining errors are usually caused by some of the sources such as cutting tool deflection, cutting tool wear, machine tool vibration, improper coolant/lubrication, and negative thermal effect. To increase product accuracy, much research has been carried out on the prediction of machining errors. However, in milling of sculptured surface parts, due to their curved shapes, the geometries of cutting tools do not match the parts’ surfaces well if the tools cut along the tool paths on the surfaces in a point-to-point way. As a consequence, machining error is inevitable, even if there is no other source of error in ideal machining conditions. To predict machining errors caused by this tool-surface mismatch, several methods have been proposed. Some of them are simple, and some represent the geometry of machined surfaces using cutter-swept surfaces. But none of these methods is accurate and practical. In this research work, a generic, geometric approach to predicting machining errors caused by the tool-surface mismatch is proposed for 3-axis sculptured surface milling. First, a new geometric model of the furrow formed by an APT tool moving between two neighboring cutter contact (CC) points is built. Second, the mathematical formula of cutting circle envelopes is derived. Then an algorithm for calculating machining errors in each tool motion is provided. Finally, this new approach is applied to two practical parts for the accurate machining-error predictions, and these predictions are then compared to the inaccurate predictions made by two established methods to demonstrate the advantages of this approach. This approach can be used in tool path planning for high precision machining of sculptured surface parts.

An Efficient, Accurate Approach to Representing Cutter-Swept Envelopes and Its Applications to Three-Axis Virtual Milling of Sculptured Surfaces

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Zezhong C. Chen ◽  
Wei Cai
Keyword(s):  
Tool Path ◽  
Basic Mechanism ◽  
Cnc Milling ◽  
Sculptured Surfaces ◽  
Machining Error ◽  
Tool Paths ◽  
Virtual Machining ◽  
Machining Errors ◽  
Computer Numerically Controlled ◽  
Swept Volume

To address a major technical challenge in simulating geometric models of machined sculptured surfaces in three-axis virtual machining, this paper presents an efficient, accurate approach to representing the 3D envelopes of a cutter sweeping sequentially through cutter locations; these envelopes embody the furrow patches of the machined surfaces. In our research, the basic mechanism of removing stock material in three-axis computer numerically controlled (CNC) milling of sculptured surfaces is investigated, and, consequently, an effective model is proposed to represent the 3D envelopes (or furrow patches). Our main contribution is that a new directrix (or swept profile) of the furrow patches (mathematically, ruled surfaces) is identified as a simple 2D envelope of cutting circles and is formulated with a closed-form equation. Therefore, the 3D cutter-swept envelopes can be represented more accurately and quickly than the existing swept-volume methods. With this innovative approach, a method of accurate prediction of the machining errors along tool paths in three-axis finish machining is provided, which is then applied to the optimization of tool-path discretization in two examples. Their results demonstrate the advantages of our approach and verify that the current machining-error-prediction methods can cause gouging in three-axis sculptured surface milling.

NURBS Curve Fitting Based on Arc Centripetal Parameterization for Tool Path Generation

2013 ◽  
Vol 274 ◽  
pp. 121-123 ◽  
Author(s):  
Cun Guang Yu
Keyword(s):  
Curve Fitting ◽  
Tool Path ◽  
Nc Machining ◽  
Tool Path Generation ◽  
Sculptured Surface ◽  
Arc Length ◽  
Tool Path Planning ◽  
Nurbs Curve ◽  
Location Data ◽  
Cutter Location Data

NURBS curve fitting is used for tool path planning for sculptured surface NC machining. The cutter location data is parameterized by equal chord arc length parameterization, and Centripetal Parameterization is improved. It is not only more approach to curves nature equation in theory, but also closer to the interpolated curves in actual fitting. It is directly to reflect the curvature of curves of cutter location in NC machining.

ROUGH MACHINING FOR MULTI-SCULPTURED SURFACES

1999 ◽  
Vol 23 (2) ◽  
pp. 275-286
Author(s):  
A. Vafaeesefat ◽  
H.A. EIMaraghy
Keyword(s):  
Cutting Planes ◽  
Tool Path ◽  
Tool Path Generation ◽  
Parallel Projection ◽  
Geometric Description ◽  
Sculptured Surfaces ◽  
Rough Machining ◽  
Tool Paths ◽  
Rough Milling ◽  
Bounding Surfaces

This paper present a method to generate 3-axis NC programs for rough milling processes. A raster digitizing of the solid volume delimitated by sculptured surfaces to be machined is first created. This is accomplished by using the so-called Z-buffer created from a parallel projection of all surfaces. Conventional rendering software can be used to generate the Z-buffer. This volume is transformed into a 3-D mesh composed of “empty”, “full”, and “mixed” blocks. Machining is preformed from top to bottom in a sequence of horizontal cutting planes. At each level of planar machining, spiral routines are used to generate the tool path. The proposed method is valid for generating tool paths for general cavities bounded by arbitrary surfaces. One of the notable advantages of the proposed method is that the tool path generation is independent from the geometric description of bounding surfaces. An example is used to illustrate the approach and its advantages.

Tool-Path Generation in Three-Axis Machining From Scanned Data of Physical Models by Using Filleted Endmills

2000 ◽  
Author(s):  
Cheng-Ming Chuang ◽  
Chun-Yan Chen ◽  
Hong-Tzong Yau
Keyword(s):  
Tool Path ◽  
Tool Path Generation ◽  
Physical Models ◽  
Free Form ◽  
Cad Model ◽  
Path Generation ◽  
Location Data ◽  
Tool Paths ◽  
Measuring Machine ◽  
Cutter Location Data

Abstract NC tool-path is usually generated by sweeping parametric surfaces of a CAD model. In modern design, free-form or sculptured surfaces are increasingly popular in representing complex geometry for aesthetic or functional purposes. Traditionally, a prototype is realized by machining the workpiece using the NC codes generated from a CAD model. The machined part can then be compared with the CAD model by measurement using a coordinate measuring machine. Presented in this paper is a reverse engineering approach to generating interference free tool-paths in three-axis machining from scanned data of physical models. There are two steps in this procedure. First, a physical model is scanned by 3D digitizers and multiple data sets are obtained of the complex model. A surface registration algorithm is proposed to align and integrate those data to construct a complete 3D data set. We use least distance method to determine the connecting sequence of the neighboring points, such that the scanned data are converted into triangular polygons. Tool-paths are then generated from the tessellated surfaces. Using the Z-map method we calculate interference-free cutter-location data relative to the vertex, edges and planes of those triangles. The algorithms for tool-path generation are usually different for cutters of various geometry. Some algorithms found in literature require complex numerical calculations and are time consuming. In this paper, an efficient algorithm is developed to calculate interference-free cutter-location data by easy geometric reasoning without complex computation. The robust method is suitable for generally used cutters such as ball, flat and filleted endmills and the time taken to obtain full tool-paths of compound surfaces is short. Some real applications are presented to validate the proposed approach.

Adaptive Tool Path Planning Strategy for 5-Axis CNC Machining of Free Form Surfaces

2019 ◽  
Author(s):  
Hrishikesh Mane ◽  
S. S. Pande
Keyword(s):  
Tool Path ◽  
Cnc Machining ◽  
Memory Storage ◽  
Free Form ◽  
Cnc Machine ◽  
Planning Strategy ◽  
Part Quality ◽  
Tool Paths ◽  
Path Topology ◽  
Free Form Surfaces

Abstract This paper presents a curvature based adaptive iso-parametric strategy for the efficient machining of free form surfaces on 5-axis CNC machine using the flat end mill tool. One iso-parametric boundary of the surface is selected as the initial tool path. Set of cutter contact (CC) points are chosen adaptively on the initial tool path considering desired profile tolerance. Adjacent iso-parametric tool paths are computed adaptively based on the scallop height constraint unlike the traditional iso-parametric approach. The path topology is post-processed to generate the part program for 5-axis CNC machine in ISO format. The system was rigorously tested for various case studies by comparing the results with the traditional 5-axis iso-parametric tool path strategy, iso-scallop strategy and iso-planar strategy of a commercial software. Our system was found to generate efficient tool paths in terms of part quality, productivity and memory storage compared to the conventional strategies.

A New Method for the Generation of Tool Paths for Finishing Near Net Shape Components

2013 ◽  
Author(s):  
Edgar A. Mendoza López ◽  
Hugo I. Medellín Castillo ◽  
Dirk F. de Lange ◽  
Theo Lim
Keyword(s):  
Geometric Modeling ◽  
Tool Path ◽  
Cutting Tools ◽  
Approximation Error ◽  
Cnc Machining ◽  
New Method ◽  
End Mill ◽  
Tool Paths ◽  
Near Net Shape ◽  
Finish Cut

The CNC machining has been one of the most recurrent processes used for finishing NNS components. This paper presents a new method for the generation of tool paths for machining 3D NNS models. The proposed approach comprises two machining stages: rough cut and finish cut, and three types of cutting tools: ball-end mill, flat-end mill and fillet-end mill. The proposed tool path generation algorithm is based on: (1) approximation of the model surfaces by points using slice planes and visibility analysis, (2) accessibility analysis of the tool, (3) approximation error and tolerance evaluation, (4) collision analysis of tool and tool holder. The tools paths generated are exported as a CNC program. The implementation was carried out in C++ using the ACIS® geometric modeling kernel to support the required geometric operations. To prove the effectiveness of the system several models with variable geometric complexity were tested. The results have shown that the proposed system is effective and therefore can be used to generate the tool paths required for finishing 3D NNS components.

Efficient NC Tool Path Planning Based on the Subdivision of Sculptured Surface

2014 ◽  
Vol 635-637 ◽  
pp. 497-501
Author(s):  
Li Min ◽  
Biao Bai ◽  
Yu Hou Wu ◽  
De Hong Zhao
Keyword(s):  
Path Planning ◽  
Tool Path ◽  
High Efficiency ◽  
Parametric Method ◽  
Sculptured Surface ◽  
Machining Efficiency ◽  
Tool Path Planning ◽  
Tool Paths ◽  
Surface Subdivision ◽  
Planning Methods

In this paper, we have presented a method to generate efficient NC tool paths based on the surface subdivision. The main objective is to achieve high efficiency in the machining of sculptured surface. The NC machining efficiency can be improved by segmenting the whole surface into distinct areas according to the characters of sculptured surface and by using different size mills and different tool path planning methods to machine the areas. The iso-parametric method and large mills are used in the curvature changing little areas. While the iso-scallop method and small mills are used in curvatures changing large areas. This can make full use of tool path generation methods and mills, which improve the machining efficiency of sculpture effectively.

An Intelligent Approach to Multiple Cutters of Maximum Sizes for Three-Axis Milling of Sculptured Surface Parts

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Zezhong C. Chen ◽  
Gang Liu
Keyword(s):  
Tool Path ◽  
Generic Model ◽  
Interference Detection ◽  
Sculptured Surface ◽  
Surface Machining ◽  
Tool Paths ◽  
Sculptured Surface Machining ◽  
Cutter Selection ◽  
Intelligent Approach ◽  
Local Gouging

Due to their complex geometries, sculptured surface parts should be machined with multiple cutters of optimal sizes for high quality and productivity. Current methods of determining cutter sizes, however, are conservative and inefficient; their repeating process includes subjective cutter selection, intensive tool-path generation, and time-consuming gouging-and-interference detection in simulation. Our research proposes a new intelligent approach to multiple standard cutters of maximum sizes for three-axis sculptured surface machining. An innovative generic model of maximum allowable cutters in three-axis surface milling is built to eliminate any cutter causing local gouging and global interference. After the optimum standard cutters are automatically selected, their accessible regions can be identified, and the corresponding tool-paths can be generated, respectively. This approach is practical and effective in the process planning for three-axis milling of sculptured surface parts.

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