The current trend in the market to solve long boring bar related chatter problems are passive dampers integrated in the boring bar, which has derived in patents and commercial products; This solution, however, is not feasible in very slender bars or trepanning operations, due to small space available in the tool. Active damping has been tested and indus-trialised in different applications, including machine tool structures, but never in internal turning tools. The application of active damping on boring bars has been proposed in several researches...
Amplified Piezo Actuators (APA®) from CEDRAT TECHNOLOGIES are known to be compact and especially performing in dynamic applications. The recent evolutions realized on the APA® and drive electronics allow them to address active damping better than magnetic proof mass in terms of the Force to Volume ratio above some 10Hz. The dynamic capability of the APA® has been improved thanks to preload method enhancement. Research has successfully shown the possibility to achieve a high dynamic force level similar to the static blocked force of the piezo actuator. This technical progress coupled with an amplified motion makes possible the generation of high mechanical proof mass load at relatively low frequency. It produces a force higher than 100N in a volume of Ø40x75mm within a range of [100-300Hz]. This paper presents relevant uses of APA® for active damping in machining applications. Several machining case studies are reported integrating Amplified Piezo Actuators within the spindle head, inside the cutting tool or beside the workpiece clamp.
The MICATM linear actuator family (Moving Iron Controllable Actuator) is being continuously improved at CEDRAT TECHNOLOGIES (CTEC) for applications needing high controllable stroke, force, and power. The MICA300CM is a new actuator model, having improved configuration based on cylindrical shape. A first version based on plain bearing offers up to 12mm stroke and 300N continuous force with a weigh of only 3kg. A second version is based on new frictionless flexure bearings. The former one is especially designed to achieve zero maintenance over several years of operation, with high efficiency, infinite resolution, and high controllability performance. This version of the MICA300CM has been derived to offer a proof mass configuration, for vibrationcancellation applications on machining processes. A latest version is also currently under design, and prototyping, specifically for reciprocating power piston applications, such as compressors, pressure wave generators, and pumps. Its high efficiency, ultra-long lifetime capability, and compactness, makes it perfectly suitable for embedded thermal machines based on Stirling, Joules Thomson, and Rankin Thermodynamic cycles. This paper presents this 4 design concepts, their test results and perspective for applications.
The objective of this paper is to provide results of an experimental and analytical investigation of Amplified Piezoelectric Actuators (APA) as vibrational isolator in a configuration of a mechanical Single Degree of Freedom system. The investigation is aimed at assessment of the mechanical properties modification ability via shunting techniques. The investigation consist of a phenomenological modelling of the APAs considered as generators and experimental verification of the vibrational energy dissipation ability in frequency domain. The results obtained during this investigation reveal that it is feasible to receive more than 20 dB reduction of the displacement amplification in the resonant range. Moreover, three tested examples of APA reveal up to 9 % of resonant frequency shift due to proper adjustment of the electronic shunting circuit, which is an encouragement for further analyses towards application of the APAs in semi-passive vibration control applications.
Modern machine tools must achieve a high precision for a better surface texture and higher flexibility for wide range of machining requirements. To fulfill these requirements, a semi-active damping system for a new generation of machine tools is proposed. The new concept is partially based on the Amplified Piezo Actuators APA® from CEDRAT Technologies. With these actuators, the dynamic behavior (stiffness and damping) of structural body components of machine tools can be controlled and adjusted to the optimum parameters. To reduce the transfer of vibrations through the active elements, a viscoelastic material was used. This article presents test results performed on the APA® with viscoelastic material. A significant reduction of the vibrational amplitude at resonance frequency was observed with additional material. The optimized quantity of viscoelastic material reduces the full stroke of the actuator only by 10 percent. At the same time, the viscoelastic material has reduced the amplitude at resonance frequency by more than double. The designed actuator obtains a blocking force of 8.5kN. Results obtained from the tests performed on the machine tool showed significant surface texture improvement with use of the amplified piezoelectric actuator.
In the field of aeronautics, some parts of aircraft engines are tricky and costly to manufacture. In the low pressure turbine very thin pieces obtained by turning require a complex support. The R&D work performed here aims at improving the manufacturing process through the reduction of vibrations and active modification of the clamping conditions. For that purpose, Cedrat Technologies has designed a new innovative Moving Iron Controllable Actuator (MICA), which is embedded on the work-piece support. In the first part, the application goals and the main particularities of the developed MICA200M magnetic actuator are presented. To be easily driven in closed loop, the force is designed to be linear with the current and independent from the interface position. The MICA200M stroke is ±2.5mm and its force constant reaches 11.6N/A for a current range of ±15A in steady state. The nominal force of 174N for only 1 dm3 size and 3.2kg facilitates the integration and allows acceleration up to 132G in transient operation thanks to reduced 0.25kg mobile mass. In the second part, results of complete experimental characterisation are detailed. Finally, a comparison analysis is done with COTS voice coil actuators and the article concludes with the benefits of the MICA200M.
Future matrix sensors will acquire an area on ground and are then susceptible to image shift due to satellite movement during acquisition. Design, Build and Test a breadboard mechanism that could shift telescope line of sight and freeze observed area during image acquisition.
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