In machinetools several time and position varying heat sources causes complex temperature distributions. The resulting problems are varying thermal deformations which cause a loss of accuracy as well as non optimal d...
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ISBN:
(纸本)9780819485397
In machinetools several time and position varying heat sources causes complex temperature distributions. The resulting problems are varying thermal deformations which cause a loss of accuracy as well as non optimal drive conditions. An option to deal with that issue is to use structure integrated SM-actuators which use the thermal energy accumulated by machining processes to yield an actuator displacement. That creates a structure inherent control loop. There the shape-memory-elements work as sensing element as well as actuation element. The plant is defined by the thermal and mechanical behaviour of the surrounding structure. Because of the closed loop operation mode, the mechanical design has to deal with questions of stability and parameter adjustment in a control sense. In contrast to common control arrangements this issues can only be influenced by designing the actuator and the structure. To investigate this approach a test bench has been designed. The heat is yielded by a clutch and directed through the structure to the shape memory element. The force and displacement of the actuator are therefore driven directly by process heat. This paper presents a broad mechanical design approach of the test bench as well as the design of the SM-actuator. To investigate the thermo-mechanical behaviour of the structure-integrated actuator, a model of the test bench has been developed. The model covers the thermal behaviour of the test bench as well as the thermo-mechanical couplings of the shape memory actuator. The model has been validated by comprehensive measurements.
Within the scope of the entire car industry, lightweight construction plays an increasingly dominating role in fulfilling requirements from a technological, environmental and economic point of view. This direction is ...
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Due to the need for a significant reduction in the weight of parts in automotive manufacturing, the use of lightweight materials such as magnesium and aluminium is becoming increasingly important. Unfortunately, these...
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In this paper we present an approach to reset a preload loss in ball screw drives which enables to compensate losses of positioning accuracy due to wear over lifetime. The main purposes are reduced maintenance, longer...
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The fraunhofer Institute for machinetools and formingtechnology has set itself the challenge of characterising the material behaviour of very recently developed sheet metal materials. To this end, an integrated conc...
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ISBN:
(纸本)9788957081525
The fraunhofer Institute for machinetools and formingtechnology has set itself the challenge of characterising the material behaviour of very recently developed sheet metal materials. To this end, an integrated concept for the determination of material characteristics has been established. This consists in further developing well-known methods based on innovative characterisation concepts for describing phenomena such as springback, anistropy and the Bauschinger Effect. Using this approach, information relating to the interaction of sheet material, lubrication and forming tool can be derived.
Increasing demands regarding the functionality and the functional density of micro fluidic systems require constant miniaturisation of single components and also of the complete system. A cost efficient and effective ...
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ISBN:
(纸本)9780956679031
Increasing demands regarding the functionality and the functional density of micro fluidic systems require constant miniaturisation of single components and also of the complete system. A cost efficient and effective manufacturing process requires replication processes such as injection moulding or hot embossing to structure disposables cost-effectively. This paper presents the development of the sequential process combination of laser micro structuring and micro milling for the manufacturing of micro fluidic moulds.
Research work aims to develop a fast, production suitable hot embossing technology including appropriate tool systems for low-cost and production-integrated manufacturing of high-precision microfluidic structures in p...
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ISBN:
(纸本)9780956679079
Research work aims to develop a fast, production suitable hot embossing technology including appropriate tool systems for low-cost and production-integrated manufacturing of high-precision microfluidic structures in polymer films. The implementation is demonstrated by structuring of microfluidic films for disposable diagnostic devices used in home-care and point-of-care applications. The approach focuses on the development and thermal design of a tool system for fast hot embossing on basis of a fast non isothermal process. Close contour tempering of the active parts is the core of this approach. Based on an industrial specification the paper will describe tempering strategy, design and simulation of the tool concept. Heat flux and heat capacities together with the power loss in the system are used for calculating the tempering cycle. Based on that, the setup of an optimized tool system consisting of heating elements and a refrigerant system is presented. The new tool concept is thermally characterized by thermocouple and infrared measurements. Furthermore the system was tested in a commercial hot embossing equipment to demonstrate the improvements. It could be shown that a cycle time between one and two minutes is possible, in comparison to cycle times of fifteen minutes in conventional hot embossing systems. Although the test system was not optimized so far, in the embossing tests all items were replicated correctly and the microfluidic function was ensured. The results of the research work are applicable also for the optimization of injection molding tool systems.
An OpenMath Content Dictionary with symbols for pattern matching of tree-like structures is presented. Furthermore, a mapping to RDF and SPARQL is introduced that allows to execute search queries against an OpenMath R...
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