Yung Cheng Wang

Development of automatic regrinding program for PC-based tool grinding machine

The main goal of this development is the PC-based controller setup on the CM2 tool grinding machine. Concerned cutting parameters with know-hows can be transferred to a useful program and then embedded in the PC-based controller. By automatic positioning of probes the automatic procedure can be achieved. An automatic and intelligent PC-based grinding machine for regrinding has been developed in this investigation. With the new machine and automatic procedure, regrinding process will be distinctly simplified. Based on a manual grinding machine CM2, a PC-based controller is integrated in the machine. The know-hows of the regrinding technology have been integrated with a self-developed program. For automatic dimensional inspection a contact probe is utilized as inspection sensor. By the programming and automatic dimensional inspection, the functions of tool regrinding machine have been enhanced greatly.

Compensation of Tilt Angles and Verification of Displacement Measurements with a Fabry-Perot Interferometer

The construction of Fabry-Perot interferometer is very simple and it has been already utilized in different measurement systems. The result of displacement measurement is obviously influenced by the tilt angles of measurement mirror, if a Fabry-Perot interferometer is utilized for displacement measurement. Hence, the measuring range of current systems is rather small (less than 1 mm). The goal of this investigation is to develop a Fabry-Perot interferometer for large travelling range (till 60 mm) by aid of compensation of tilt angles with an angular sensor, piezo translators, control mechanism and self-designed software. To verify the measuring characteristic of the self-developed Fabry-Perot interferometer, some comparison measurements have been performed. A commercial laser interferometer serves as reference standard and the differences between Fabry-Perot interferometer and the commercial Laser interferometer are measured. Through experimental tests, the differences are less than 0.3 m in the full measurement range. The results show that the Fabry-Perot interferometer can meet the measuring requirement with high accuracy of sub-micrometer order and large measurement range.

A Compact Signal Processing with Position Sensitive Detectors Utilized for Michelson Interferometer

Interferometric signals of a homodyne Michelson interferometer appear in sinusoidal forms. In this investigation, new concepts for signal processing of Michelson interferometer are demonstrated. With the utilization of detection of position sensitive detector (PSD) and by the procedure of differential signals and the characteristic of symmetric waveform, a compact signal processing for homodyne Michelson interferometer has been developed. Its advantages include simplified procedure, fast processing and few electronic hardware. For experiment tests of the signal processing, a conventional homodyne Michelson interferometer has been constructed. Major components of the interferometer consist of laser light source, beam splitter, mirrors, PSD and piezo transducer for driving measurement mirror. To verify the performance of the signal processing, a commercial nanopositioning stage as reference standard has been utilized for comparison measurements. Through theoretical analysis and experiment tests, it can be proved that by the developed signal processing an interferometer possesses the optical resolution of 79 nm. With support of the developed signal processing, interferometers will possess the benefits of simply structure, few components and lower cost.

Sensing Mechanical Properties of Solid Materials with Bimorph Piezotransducers

Mechanical properties of materials, such as Youngs modulus, shear modulus andlinear viscoelastic damping, are experimentally measured with a thin- lm cantilever shaker. Theexperimental apparatus consists of a bimorph piezoelectric transducer acting as an actuator togenerate base excitation to the cantilever, which is analogous to earthquake causing buildingvibration. The motion of the cantilever is monitored by a pair of ber optics to measure thedisplacements of the xed end and the sample. Linear viscoelastic properties of the materialare measured from the resonant frequencies of the vibrating cantilever. Youngs modulus andshear modulus are measured from bending and torsion resonant peaks, respectively. For highloss materials, loss tangent of the materials is obtained from the Lorenzian curve t around theresonant peak. Material properties at various frequencies are measured by changing the lengthof the specimens. Furthermore, by introducing crack-like defects, the measured resonances,which may be viewed as a measure of e ective moduli, are able to be adopted to locate thecrack via the method of system identi cation.

The Predictive Model of Surface Integrity in End-Mill Grinding for High-Speed Milling

The grinding precision of end-mill is dependent on the surface roughness of the corresponding rake face and relief face. This precision will be influential in the surface roughness of workpiece and tool life of end-mill in high-speed milling. Firstly, the experiment of high-speed milling for SKD61 tool steel has been performed in the different cutting condition, and the end-mills have the different surface roughness. From the experimental results, it has shown that small relief surface roughness will decrease tool flank wear (increase tool life). The surface integrity of end-mill is very important for high-speed milling, so the different grinding parameters of end-mill have been utilized in the grinding experiment. Finally the surface roughness analysis model of the end-mill relief could be established by a polynomial network. The predictive model of surface roughness can be used to analyze the grinding precision of end-mill.

Simulation of Thermal Deformation for Spindle of Machine Tool

In order to increase the efficiency of machine tools, the development of machine tools is toward higher speed and accuracy. The higher speed of spindle causes more thermal deformation, which reduces the accuracy of machine tools. In this study, finite element method is used to simulate the thermal deformation of spindle caused by the friction loads between spindle and bearings. The bearing load is estimated by the basic load rating from the bearing vendor and the required life of bearing. The simulated results are compared with experimental measurements to verify the analysis model. The result shows that the stabilized temperature of spindle increases as the speed increaser, while the stabilized displacement of spindle slightly increases as the speed increases.

The Predictive Model of Surface Roughness and Searching System in Database for Cutting Tool Grinding

Due to the rapid development in recent cutting technology, demands for different types of precise cutting tools become increasingly complicated. Since the design and grinding of end-mills are the last and the most important processing for cutting tools. The geometrical accuracy and the cutting performance of an end-mill depend essentially on the grinding. However, the complicated geometry of an end-mill will be ground by the specific software of CAD/CAM on the 5-axis CNC tool grinding machine. The precision of end-mill grinder will be determined by the performance of 5-axis CNC tool grinder and setting of grinding parameters. Three regulation factors for grinding are grit size of the diamond grinding wheel, grinding speed and the feeding speed. The variable ranges of each parameter can be divided in large, medium and small interval. In this study for an end-mill with fixed geometrical profile, a series of different grinding parameters have been utilized by the 33 factorial experiment planning. And tool grinding experiments for the rod material specification of tungsten carbide have been performed by 5-axis CNC tool grinder. After grinding, surface roughness of tools will be measured. The reliability and precision of the end-mill grinding can be enhanced by the prediction model of polynomial network for surface roughness of end-mills. Besides, the database system for cutting tool has benn established. Totally 4802 data were constructed in the relational database according to the characteristics of tools.

Abbe Error-Free Test Equipment for Nanometer-Order Measurements

In order to ensure manufacturing quality, precise measuring instruments and sensors play an important role for the accurate measurement of products. For length measurements with submicrometer precision, the nano gauging displacement transducers (NGDT) have been often utilized. NGDT can achieve a resolution in the nanometer order and an accuracy of less than 100 nm. To guarantee the accuracy and the traceability to the definition of the meter, calibration and test of NGDT are necessary. The current methods and machines suffer from various disadvantages. Some of them allows only manual test procedures and some automatic tests can reach only uncertainties of more than 100 nm. To realize an automatized and accurate test of NGDT, a test equipment was developed, that with a resolution of 1.24 nm, a measuring range up to 20 mm and a measuring uncertainty of approximate ±10 nm can fulfil the test requirements. The main problem for realization of this test system is minimization of the Abbe error which is a first order error and will result in a significant error. For reaching this goal an angular control system and piezo translators are applied. With the aid of a measuring program adhering to the measurement principle outlined in VDI/VDE 2617 guidelines, an automatic test less than thirty minutes was realized. By theoretical and experimental investigations it can be shown that the automatic test equipment achieves a test uncertainty of approximate ± 10 nm corresponding to a relative uncertainty of approximate ± 5.10 -7 . With small uncertainty and short test time, this test system with an Abbe error-free stage is available for the accurate test of high precision gauging displacement transducers.

Untersuchungen zur Gleichzeitigen Längen- und Winkelmessung mit einem Planspiegelinterferometer (Simultaneous Length and Angle Measurement with a Plane Mirror Interferometer)

Die Anwendung der optischen Interferometrie hat eine große Bedeutung in der Präzisionsmessung, insbesondere für die Längen- und Winkelmessung. Bei der Längenmessung mit Planspiegeln ist es oft von großem Interesse, neben der Verschiebung auch den Kippwinkel des Messspiegels zu kennen. In der Regel benötigt man dazu ein zusätzliches Winkelmesssystem, z.B. ein Autokollimationsfernrohr oder ein bzw. zwei (für Nick- und Gierwinkel) Winkelinterferometer. Hier soll anhand einer theoretischen Analyse nachgewiesen werden, dass man bei der interferometrischen Längenmessung mit dem Ausgangssignal bestimmter Interferometer gleichzeitig auch den Winkel des Messspiegels in zwei Richtungen bestimmen kann. Mit dieser Methode kann eine Genauigkeit der Winkelmessung von 2´´ erzielt werden.