An efficient method for solving the Signorini problem in the simulation of free-form surfaces produced by belt grinding

Industrial robots are recently introduced to the belt grinding of free-form surfaces to obtain high productive efficiency and constant surface quality. The simulation of belt grinding process can facilitate planning grinding paths and writing robotic programs before manufacturing. In simulation, it is crucial to get the force distribution in the contact area between the workpiece and the elastic contact wheel because the uneven distributed local forces are the main reason to the unequal local removals on the grated surface. The traditional way is to simplify this contact problem as a Signorini contact problem and use the finite element method (FEM) to calculate the force distribution. However, the FEM model is too computationally expensive to meet the real-time requirement. A new model based on support vector regression (SVR) technique is developed in this paper to calculate the force distribution instead of the FEM model. The new model approximates the FEM model with an error smaller than 5%, but executes much faster (1 s vs 15 min by FEM). With this new model, the real-time simulation and even the on-line robot control of grinding processes can be further conducted.     

State and potentials of the “Virtual Forming Press”

This article summarizes the state of the model-based analyzing methods. Furthermore, it depicts the application potentials of the so-called “Virtual Press” in fields of press design and development. Continuative applications in manufacturing and operational use of presses are presented. Moreover, the model fundamentals, developed in Wiemer (Stand und Möglichkeiten der Systemsimulation von mechanischen Pressmaschinen für die Blechumformung. Ph. D. Thesis, Technische Universität Dresden 2004), are briefly explained. The paper concludes with application examples for the “Virtual Press” like for dimensioning of the drive systems of a six-ram press with offset in the crank angles, for simulation of reversal clearance at joint of the crank gear and for work piece specific press selection.     

Automatic classification of defects on the product surface in grinding and polishing

Grinding and polishing are standard operations in material processing. It is important to inspect and classify the potential defects existing on the product surfaces after grinding and polishing in order to obtain high quality in both functionality and aesthetics. Post-processing handling can be carried out after the defects have been correctly classified. A vision system already exists to detect and classify defects based on captured grayscale images automatically. The system is able to find and locate the defects precisely, but is incapable of placing those defects into the right predefined classes. The old system classifies the defects 30% of the time into the 15 predefined classes based on shape features. In this paper, a new classification strategy has been introduced using diverse extracted features. In addition to shape features, some other feature extraction methods were tried, e.g. Laws filter bank, DCT (Discrete Cosine Transformation) filter bank, Gabor filter bank, and statistical features based on co-occurrence matrix. The Support Vector Machine (SVM) was used as a multi-class classifier with input of the extracted features. By combining the Gabor filter features and the statistical features, the classification rate of the system can reach 82% overall right rate, which is applicable practically.     

Manufacturing simulation of beveloid gears for the use in a general tooth contact analysis software

Beveloid gears, also known as conical involute gears, gain more and more importance in industrial practice. They are based on cylindrical gears but have a variable addendum modification along their tooth width. For marine transmissions beveloids are already deployed for a longer period, but there is a growing interest in this type of gears on the part of the automobile industry. Unfortunately the behavior of beveloid gears is not as well understood as the behavior of spur or bevel gears. Therefore the possibilities to evaluate these behaviors have to be enhanced. This paper shows a manufacturing simulation of beveloid gears and the usage of the generated geometries in a general tooth contact analysis program.     

New method for determination of the pose of the grinding wheel for thinning drill points

Traditionally, twist drills are reconditioned by thinning the web so the correct chisel edge length is restored. Recently, thinning has been included in the original design of drills so as to reduce torque and tool force. Because the International Standards Organization (ISO) has a system which can comprehensively model conventional twist drills but cannot model thinning specifications, this paper presents a system for precise mathematical modeling and CNC control of a 6-axis grinding workstation for drill thinning. The presented method determines the position and orientation of the grinding wheel based on the evaluated rake and clearance angles of ISO standards for 2-flute twist drills. The mathematical model and background are discussed. For verification and demonstration, two experimental drills are produced to the identical ISO standard except that one is thinned. The modeling herein is of value to industry and research if incorporated into computer software for drill design and manufacture. It is suitable for linear notch-type cutting with controlled variable rake angle along the secondary cutting edge for purposes of thinning, notching, dubbing and advanced drill research.     

Information model for the integration of inspection activity in a concurrent engineering framework

The basis of the integration of activities related to the product life cycle is, mainly, the creation of a unique and coherent information model along all the stages in the cycle. Up to date, dimensional inspection activities have not been deeply analysed, possibly due to the fact that, their work influences are smaller than others, such us numerical analysis, materials or numerical control. However, the integration of dimensional inspection is very important for several reasons: the need of specifying the design and planning of the inspection process from the conceptual part design; the increase of use of high speed coordinate measuring machine (CMM) in the production lines; and finally, for the interest of a feedback between data inspection and manufacturing processes. This paper is a detailed proposal of an information model for inspection based on operations for CMM, which represents a consistent structure of the necessary data in an integrated product setting.