scholarly journals Accuracy Improvement of a Machine Kinematics for the Product Flexible Machining of Curved Extrusion Profiles

2008 ◽  
Vol 43 ◽  
pp. 135-144
Author(s):  
Jürgen Fleischer ◽  
Jan Philipp Schmidt-Ewig
Keyword(s):  
Traffic Engineering ◽  
Complex Geometry ◽  
Frame Structures ◽  
Work Piece ◽  
Machining Accuracy ◽  
Process Chain ◽  
Space Frame ◽  
Frame Design ◽  
Machining Center ◽  
Technical Effort

Within traffic engineering, the importance of lightweight space frame structures continuously grows. The space frame design offers many advantages for light weight construction but also brings challenges for the production technology. For example, the important requests concerning product flexibility and reconfiguration can only be achieved with a high technical effort, if current machine technology is used. For this reason, the collaborative research center SFB/TR10 investigates the scientific fundamentals of a process chain for the product flexible and automated production of space frame structures. An important component in space frame structures are curved extrusion profiles. Within the investigated process chain, the extrusions must be machined mechanically in order to apply holes and to prepare the extrusion ends for the following welding operation.The machining is currently done by clamping the profile into a fixture and processing it within a machining center. This procedure has two disadvantages due to the complex geometry and the partially high length of the extrusion profiles: On the one hand, a complex fixture is needed for clamping the work piece [1]. On the other hand, a machining center with a large workspace and five machine axes is required [2]. Due to this, the product flexible machining with current technology is only possible with high technical and economical effort. For this reason, a new machine concept for the product flexible machining of three dimensionally curved extrusion profiles was developed at the University of Karlsruhe. In this paper, the function of the machine is explained and a prototype is presented. In addition, investigation results of the machining accuracy are shown and possibilities for improving the precision are discussed.

Swirling Fluidized Bed Polishing: A New Non-Conventional Method of Surface Modification

2015 ◽  
Vol 813-814 ◽  
pp. 634-640
Author(s):  
N.K. Francis ◽  
K.G. Viswanadhan ◽  
M.M. Paulose
Keyword(s):  
Surface Modification ◽  
Fluidized Bed ◽  
Metal Removal ◽  
Complex Geometry ◽  
Removal Rate ◽  
Abrasive Particle ◽  
Surface Finishing ◽  
Polished Surface ◽  
Work Piece ◽  
Machining Accuracy

Swirling Fluidized Bed Polishing (SFBP) is a non–traditional alternative abrasive flow surface finishing form of Fluidized Bed Machining (FBM) in which the former has special features to overcome certain significant limitations of the latter, namely the variation of the surface roughness vertically along the component surface and the screening effect owing to the complex contours in the work piece geometry. Owing to its ability to perform machining and generate polished surface from a roughness value of Ra 1.2μ to 0.2 μ within 8 hours of processing, this new method offers greater scope in the surface modification of rough machined surfaces with complex geometry such as component with ducts and grooves. This research focus on investigating the effect of abrasive particle concentration on metal removal rate per unit area of the specimen surface. 3D surface morphology analysis investigates the quality of the polished surface and the study of circumferential uniformity and machining accuracy analysis on a complex-contoured component further investigate its scope and relevance in industrial applications.

Rationalization of freeform space-frame structures: Reducing variability in the joints

2020 ◽  
Vol 18 (1) ◽  
pp. 84-99
Author(s):  
Antiopi Koronaki ◽  
Paul Shepherd ◽  
Mark Evernden
Keyword(s):  
Large Scale ◽  
Complex Geometry ◽  
Geometry Optimization ◽  
Control Surface ◽  
Frame Structures ◽  
Computationally Efficient ◽  
Space Frame ◽  
Computational Workflow ◽  
Doubly Curved

In recent years, the application of space-frame structures on large-scale freeform designs has significantly increased due to their lightweight configuration and the freedom of design they offer. However, this has introduced a level of complexity into their construction, as doubly curved designs require non-uniform configurations. This article proposes a novel computational workflow that reduces the construction complexity of freeform space-frame structures, by minimizing variability in their joints. Space-frame joints are evaluated according to their geometry and clustered for production in compliance with the tolerance requirements of the selected fabrication process. This provides a direct insight into the level of customization required and the associated construction complexity. A subsequent geometry optimization of the space-frame’s depth minimizes the number of different joint groups required. The variables of the optimization are defined in relation to the structure’s curvature, providing a direct link between the structure’s geometry and the optimization process. Through the application of a control surface, the dimensionality of the design space is drastically reduced, rendering this method applicable to large-scale projects. A case study of an existing structure of complex geometry is presented, and this method achieves a significant reduction in the construction complexity in a robust and computationally efficient way.

Machining Accuracy Improvement by Automatic Tool Setting and On Machine Verification

2008 ◽  
Vol 381-382 ◽  
pp. 199-202 ◽  
Author(s):  
E.S. Lee ◽  
C.H. Lee ◽  
Sung Chung Kim
Keyword(s):  
Cnc Machining ◽  
Work Piece ◽  
Machining Accuracy ◽  
Accuracy Improvement ◽  
Machining Center ◽  
Probe System ◽  
Tool Setting ◽  
Automatic Tool ◽  
Cnc Machining Center

This paper proposes a methodology for improving the machining accuracy based on auto tool setting & work-piece measuring on the machine using laser tool setting system & inspection probe. In this study, laser tool setting systems were analyzed as considering principles, convenience and efficiency and auto tool setting method and operating macro software were developed. As compared with conventional manual tool setting and touch-type auto tool setting, the importance of automatic non-contact tool setting using laser tool setter has been discussed. Also correct tool-setting methods in accordance with different tool shapes and sizes were defined and pocket features were machined by each of setting tools and measured by the inspection probe system to verify machining accuracy. Lastly we tried to demonstrate the superiority of laser tool setting systems by analyzing the cutting results when the CNC machining center was fitted with laser tool setting system.

Experiment Study on Deflection of Aluminum Alloy Thin-Wall Workpiece in Milling Process

2011 ◽  
Vol 697-698 ◽  
pp. 129-132 ◽  
Author(s):  
Bing Han ◽  
Cheng Zu Ren ◽  
X.Y. Yang ◽  
Guang Chen
Keyword(s):  
Aluminum Alloy ◽  
Coordinate Measuring Machine ◽  
Milling Process ◽  
Cnc Machining ◽  
Machining Accuracy ◽  
Thin Wall ◽  
Machining Center ◽  
Machining Errors ◽  
Alloy Material ◽  
Measuring Machine

The deflection of Aluminum alloy thin-wall workpiece caused by the milling force leads to additional machining errors and reduces machining accuracy. In this paper, a set of experiments of milling thin-wall workpiece were carried out to study the deflection of thin-wall workpiece. The workpieces, with different types of material and different thicknesses, were machined on CNC machining center. The deflections of workpiece were measured by a three-coordinate measuring machine. Effects of Aluminum alloy material and thickness on deflection are discussed based on the experimental data.

Dynamic Characteristics Analysis for the Headstock of a Vertical Machining Center

2016 ◽  
Vol 836-837 ◽  
pp. 348-358
Author(s):  
Zhe Li ◽  
Song Zhang ◽  
Yan Chen ◽  
Peng Wang ◽  
Ai Rong Zhang
Keyword(s):  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Vibration Characteristics ◽  
Numerical Control ◽  
Vibration Test ◽  
Machining Accuracy ◽  
Modal Test ◽  
Machining Center ◽  
Characteristics Analysis ◽  
Nc Machine

Dynamic characteristics of numerical control (NC) machine tools, such as natural frequency and vibration property, directly affect machining efficiency and finished surface quality. In general, low-order natural frequencies of critical components have significant influences on machine tool’s performances. The headstock is the most important component of the machine tool. The reliability, cutting stability, and machining accuracy of a machining center largely depend on the structure and dynamic characteristics of the headstock. First, in order to obtain the natural frequencies and vibration characteristics of the headstock of a vertical machining center, modal test and vibration test in free running and cutting conditions were carried out by means of the dynamic signal collection and analysis system. According to the modal test, the first six natural frequencies of the headstock were obtained, which can not only guide the working speed, but also act as the reference of structural optimization aiming at frequency-shift. Secondly, by means of the vibration test, the vibration characteristics of the headstock were obtained and the main vibration sources were found out. Finally the corresponding vibration reduction plans were proposed in this paper. That provides the reference for improving the performance of the overall unit.

A Small-Line Segment Dynamic Transition Algorithm Based on Axial Error Tolerance

2016 ◽  
Vol 851 ◽  
pp. 433-438
Author(s):  
Shu Jie Sun ◽  
Hu Lin ◽  
Liao Mo Zheng ◽  
Jin Gang Yu ◽  
Bei Bei Li ◽  
...  
Keyword(s):  
Tool Path ◽  
Maximum Velocity ◽  
Error Tolerance ◽  
Contour Error ◽  
Work Piece ◽  
Machining Accuracy ◽  
Machining Efficiency ◽  
Processing Efficiency ◽  
Dynamic Transition ◽  
Machining Quality

To ensure the machining precision of work piece and improve the machining quality and machining efficiency, a dynamic transition method based on axial machining accuracy is given. Firstly, the maximum machining contour error is computed based on the axial machining accuracy, and the tool path is processed based on the machining contour error to reduce the amount of command points. Secondly, the circle transition method is used to make the tool path smoother and the machining efficiency higher. Finally, the radius of the transition circle is adjusted based on the maximum velocity of each transition circle. The experimental results shows that the method proposed could effectively satisfy the needs of the machining accuracy and improve the processing efficiency, while reduce the amount of path data.

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