3,595 research outputs found
Optimization of 5-Axis milling processes based on the process models with application to airfoil machining
5-axis milling is widely used in machining of complex surfaces such as airfoils. Improper selection of machining parameters may cause low productivity and undesired results during machining. There are several constraints such as available power and torque, chatter stability, tool breakage etc. In order to respect such constraints proper machining parameters should be determined. In this paper, methodologies for improving 5-axis milling processes are presented. Selection of machining parameters is performed using process simulations. The developed methodologies are presented on an example airfoil
A novel haptic model and environment for maxillofacial surgical operation planning and manipulation
This paper presents a practical method and a new haptic model to support manipulations of bones and their segments during the planning of a surgical operation in a virtual environment using a haptic interface. To perform an effective dental surgery it is important to have all the operation related information of the patient available beforehand in order to plan the operation and avoid any complications. A haptic interface with a virtual and accurate patient model to support the planning of bone cuts is therefore critical, useful and necessary for the surgeons. The system proposed uses DICOM images taken from a digital tomography scanner and creates a mesh model of the filtered skull, from which the jaw bone can be isolated for further use. A novel solution for cutting the bones has been developed and it uses the haptic tool to determine and define the bone-cutting plane in the bone, and this new approach creates three new meshes of the original model. Using this approach the computational power is optimized and a real time feedback can be achieved during all bone manipulations. During the movement of the mesh cutting, a novel friction profile is predefined in the haptical system to simulate the force feedback feel of different densities in the bone
Implementing Rapid Prototyping Using CNC Machining (CNC-RP) Through a CAD/CAM Interface
This paper presents the methodology and implementation of a rapid machining system using a
CAD/CAM interface. Rapid Prototyping using CNC Machining (CNC-RP) is a method that has
been developed which enables automatic generation of process plans for a machined component.
The challenge with CNC-RP is not the technical problems of material removal, but with all of
the required setup, fixture and toolpath planning, which has previously required a skilled
machinist. Through the use of advanced geometric algorithms, we have implemented an
interface with a CAD/CAM system that allows true automatic NC code generation directly from
a CAD model with no human interaction; a capability necessary for a practical rapid prototyping
system.Mechanical Engineerin
Geometry and tool motion planning for curvature adapted CNC machining
CNC machining is the leading subtractive manufacturing technology. Although it is in use since decades, it is far from fully solved and still a rich source for challenging problems in geometric computing. We demonstrate this at hand of 5-axis machining of freeform surfaces, where the degrees of freedom in selecting and moving the cutting tool allow one to adapt the tool motion optimally to the surface to be produced. We aim at a high-quality surface finish, thereby reducing the need for hard-to-control post-machining processes such as grinding and polishing. Our work is based on a careful geometric analysis of curvature-adapted machining via so-called second order line contact between tool and target surface. On the geometric side, this leads to a new continuous transition between “dual” classical results in surface theory concerning osculating circles of surface curves and oscu- lating cones of tangentially circumscribed developable surfaces. Practically, it serves as an effective basis for tool motion planning. Unlike previous approaches to curvature-adapted machining, we solve locally optimal tool positioning and motion planning within a single optimization framework and achieve curvature adaptation even for convex surfaces. This is possible with a toroidal cutter that contains a negatively curved cutting area. The effectiveness of our approach is verified at hand of digital models, simulations and machined parts, including a comparison to results generated with commercial software
Topological model for machining of parts with complex shapes
Complex shapes are widely used to design products in several industries such
as aeronautics, automotive and domestic appliances. Several variations of their
curvatures and orientations generate difficulties during their manufacturing or
the machining of dies used in moulding, injection and forging. Analysis of
several parts highlights two levels of difficulties between three types of
shapes: prismatic parts with simple geometrical shapes, aeronautic structure
parts composed of several shallow pockets and forging dies composed of several
deep cavities which often contain protrusions. This paper mainly concerns High
Speed Machining (HSM) of these dies which represent the highest complexity
level because of the shapes' geometry and their topology. Five axes HSM is
generally required for such complex shaped parts but 3 axes machining can be
sufficient for dies. Evolutions in HSM CAM software and machine tools lead to
an important increase in time for machining preparation. Analysis stages of the
CAD model particularly induce this time increase which is required for a wise
choice of cutting tools and machining strategies. Assistance modules for
prismatic parts machining features identification in CAD models are widely
implemented in CAM software. In spite of the last CAM evolutions, these kinds
of CAM modules are undeveloped for aeronautical structure parts and forging
dies. Development of new CAM modules for the extraction of relevant machining
areas as well as the definition of the topological relations between these
areas must make it possible for the machining assistant to reduce the machining
preparation time. In this paper, a model developed for the description of
complex shape parts topology is presented. It is based on machining areas
extracted for the construction of geometrical features starting from CAD models
of the parts. As topology is described in order to assist machining assistant
during machining process generation, the difficulties associated with tasks he
carried out are analyzed at first. The topological model presented after is
based on the basic geometrical features extracted. Topological relations which
represent the framework of the model are defined between the basic geometrical
features which are gathered afterwards in macro-features. Approach used for the
identification of these macro-features is also presented in this paper.
Detailed application on the construction of the topological model of forging
dies is presented in the last part of the paper
Manufacturing Processes of Integral Blade Rotors for Turbomachinery, Processes and New Approaches
Manufacturing techniques applied to turbomachinery components represent a challenge in the aeronautical sector. These components are commonly composed of high resistant super-alloys; in order to satisfy the extreme working conditions, they have to support during their useful life. Besides, in the particular case of Integrally Bladed Rotors (IBR), they usually present complex geometries that need to be roughed and finished by milling and grinding processes, respectively. Thermoresistant superalloys present many challenges in terms of machinability what leads to find new alternatives to conventional manufacturing processes. In order to face this issue, this work presents a review of the last advances for IBR manufacturing and repairing processes.We are grateful to Basque Excellence university Groups IT IT1337-19, and Ministry of economy project IBRELIABLE (DPI2016-74845-R), and Elkartek PROCODA KK 2019-004
Surface Roughness Control Based on Digital Copy Milling Concept to Achieve Autonomous Milling Operation
AbstractIn order to develop an autonomous and intelligent machine tool, a system named Digital Copy Milling (DCM) was developed in our previous studies. The DCM generates tool paths in real time based on the principle of copy milling. In the DCM, the cutting tool is controlled dynamically to follow the surface of CAD model corresponding to the machined shape without any NC program. In this study, surface roughness control of finished surface is performed as an enhanced function of DCM. From rough-cut to semi-finish-cut and finish-cut operations, the DCM selects cutting conditions and generates tool paths dynamically to satisfy instructed surface roughness Ra. The experimental verification was performed successfully
A CAD/CAM concept for High Speed Cutting compatible rough machining in die, mould and pattern manufacturing
Die, mould and pattern manufacturing plays a central role in the production of capital
and consumer goods. Ever-shorter product life cycles and the expanding diversity of
features require continued cuts in production lead times.
Recently, these developments in the market, accompanied by a simultaneous demand
for improved quality at a lower cost, are becoming clearly noticeable. Along with the
streamlining of organizational structures and advanced technological developments,
it is above all the introduction of CAD/CAM software that offers great potential for
reducing lead times for components with free surfaces.
The role of milling in the integrated process chain of die, mould and pattern manufacturing
is steadily gaining importance. This is due to the ongoing further development
of milling-machine technology, the cutting tools and their coatings, and of the
CAD /CAM systems themselves. Generally speaking, the milling process is divided
into the operations of roughing and finishing. For rough milling, efficient machining
means high stock-removal rates together with close contour approximation and low
tool wear. Rough milling is normally carried out layer by layer, i.e. in a 2.SD machining
operation with constant depth per cut because the rate of material removal and
process reliability are usually highest when this method is used. High-speed cutting
(HSC), which has been the subject of extensive university research for far more than
ten years, has meanwhile become established as a finishing process in many companies.
However, the application of HSC demands the observance of geometric and,
above all, technological constraints. A considerable degree of optimization can be
achieved when these constraints are applied to rough milling.
In the integrated process chain, the CAD/CAM system performs the task of calculating
NC programs based on CAD data which meet the requirements posed by
rough and finish machining operations. While general interest was focused on the
development of CAM strategies for HSC finish machining, advanced development of
technology-oriented CAM modules for upstream roughing operations was neglected.
The paper at hand deals with the development of a CAM module for rough-machining
complex components in die, mould and pattern manufacturing. It provides an insight
into the process-technological demands made on HSC operations and their application
in rough machining, from which guidelines and requirements on technologically oriented NC functions for CAM software were derived. These encompass both the
complete development of an interactive, dialogue-based user guidance function and
the algorithmic conversion of the calculation routines. The concept at hand was almost
entirely implemented and integrated in the CAD/CAM system developed by
Tebis AG, Germany, which was conceived especially for die, mould and pattern manufacturing
and is scheduled for introduction to the free market starting in April 2001
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