Glue-Based Adaptive Fixation
Development of Technology of Adaptive Electrorheological Glue-Based Fixation of Machined Workpieces
Tech Area / Field
- MAN-MAT/Engineering Materials/Manufacturing Technology
- MAN-MCH/Machinery and Tools/Manufacturing Technology
3 Approved without Funding
National Academy of Sciences of the Republic of Belarus / Institute of Heat and Mass Transfer / Plasmactor Co. Ltd, Belarus, Minsk
- Yamagata University, Japan, Yamagata
The goal of the present project is the development of a technology of efficient controllable electrorheological fixture units (ERFU) for all kinds of materials. This goal is multibranched, it requires for tackling both the experimental (including engineering aspects) and theoretical problems.
One of the most significant problems in modern production is the development and manufacture of special machine - tool equipment used for machining. Today approximately 20 million special and universal devices are employed. Their design and manufacture frequently account for 80% of the labour and 90% of the time spent preparing the machining. The expense of the equipment accounts for 10 to 15% of the cost of articles.
In modern practice different clutches are used variously based on hydraulic, vacuum, magnetic, mechanical (bolts, clamps, special clutches), electrostatic principles, as well as glue and compounds. The kind of contact can be point, linear, plane, or solid. For reasons connected with machining conditions and surface easy of access, flat clutches are usually preferable. They are employed in electromagnetic, magnetic, vacuum, and electrostatic devices. The basic advantage is uniformity, relative stability, and essential, distributed attractive force. For example, electromagnetic clutches are known to cause a specific attractive force of between 20 and 700 kPa depending on the thickness of metal part, electrostatic clutches 300 to 450 kPa, and vacuum devices from 60 to 80 kPa force.
The application of magnetic clutches is restricted by the fact that they can be applied only with magnetizable parts and attractive force depends on the thickness of parts. When a foil - like part is less than 1,5 - 2,0 mm thick, the force is too small, besides, the heating caused by associated high current power supplies confines their use. Vacuum clutches cannot be applied to perforated parts; their use is also restricted by the requirement that the compression force on any elastic interlayer be less than the clamping force acting upon the parts - otherwise, the interlayer deflects, thus violating the device seal.
The clamping principle of electrostatic clutches (EC) is based on surface effect, therefore, thin articles will be held by the some force as thick ones. In EC, the electric field energy is immediately converted into a mechanical attractive force. But industrial application is restricted due to insufficient stability of attractive force, i.e. its decrease with respect to time within a machining operation, on account of low bottom surface, and high requirements for finishing of support surface, necessitate connecting one of the electric contacts directly to a machined work. These shortcomings have been eliminated partially by using a fluid composition semiconducting interlayer with field - dependent viscosity and elasticity - electrorheological fluids (ERF). [Klaas, D.H., Martinek, T.W. Electroviscous Fluids, Electrorheological Properties. 1967. - V.38, N1. - P.75 - 79.]. The fixing ability of such a electrorheological composition in electrorheological clutches (ERC), is based on the structural effect. It was found that two conducting plates pided by dielectric fluid (ERF) having fine solid particles suspended in an insulating liquid and certain admixtures (surfactants, activators) would act as a single whole while a potential difference exists between them. This ERF property has been applied to use in ERC where a conducting object placed on a covered dielectric plate would be rigidly clutched by the "solidified" film when a high electric field was applied. Some attempts to develop ERC are known [Patent USA 3197682. Safe Electro-responsive chuck / Klaas, D.H., Martinek, T.W.], [Коробко Е.В., Раготнер М.М., Городкин Р.Г., Букович И.В., Гайнутдинов Н.В., Яшин А.Н., Сафин Р.Г. Электрореологическая оснастка для фиксации деталей // Механизация и автоматизация. - 1990. - N4. C.16 - 18.]. It is supposed to achieve several times fold increase of precision (unevenness) of processing of end places as compared to the precision attained presently in conventional modern industrial equipment in which its structural elements are used to fix a non-rigid construction. The ER fixture technology may also be applied in robotics.
At ASC HMTI NAS of Belarus more than 30 years experimental and theoretical studies were carried out concerned with rheology and hydromechanics of electrostructurized fluid compositions, specific behavior of which is attributed to shear and electrical strengths and the fluid components. The outcome of the investigations is about 250 published works and more than 100 issued patents.
Implementation of the present project will result in development of a unique technology of multipurpose ER glue-based fixture units for needs of mechanical engineering and robotics which provide the possibility gripping and fixture of two- and three-dimensional blanks from materials of all kinds during machining and their transportation. The ER glue compositions and the technology of their preparation present know-how.
The forecasted market for a technology of multipurpose fixture units is rather vast by experts evaluations. Replacement of even 15-20 % of the conventional gripping devices in service by the ER-glue based fixture units can save billions of dollars and considerably increase labour productivity.
After completion of the project it is expected to obtain patents on the ER glue composition and the fixture unit.
Implementation of the present project provides the opportunity for weapon scientists and engineers the peaceful scientific and research activity; the integration of weapons scientists of Belarus into the international scientific community; the self-sustaining civilian activities of scientists of Belarus; the transition to market-based economies; the potential opportunities for manufacture of machinery, development of technology of adaptive electrorheological glue-based fixation of workpieces during machining, that meet commercial needs and respond to national priorities of Belarus; participation of collaborators with specific skills in management, marketing, and commercialization; to exploit project results for manufacture of equipment and items of automotive, robotics, airspace, shipbuilding, and energy machinery industries.
To carry out the proposed work, it is planned to solve five major interrelated tasks which involve development of ER glue compositions, investigation of their physical and chemical characteristics, determination of fixture strength of the proposed ER glue-based units, optimization of the technology of application of ER fixture units. For this, the specialized experimental facilities will be employed.
The foreign collaborator in the present project is the Nice University (France). The role of the foreign collaborator is coordination of the investigations, exchange of scientific and technical information, joint use of the equipment, collaborative discussion of scientific results, conduction of joint seminars, workshops, consultations and marketing of the technologies developed.
An ER glue technology is planned to develop on the basis of the methods of colloid chemistry, physical chemistry of surface phenomena, structural rheology, physics of semiconductors and dielectrics. The rheological properties will be investigated by the methods of rotational and capillary viscosimetry in the presence of electric fields of different intensity in a wide frequency range. The thermophysical characteristics will be determined by the methods of unsteady- and steady-state heat fluxes. Determination of the dependence of force characteristics (fixing force) on the structural and rheological characteristics of an ER glue, machining conditions will be carried out using the electronic tensometric devices. To test the ERFU technology, the specialized equipment will be created for fixing of monolithic workpieces, thin-walled items, non-rigid parts and ER gripping devices at the units of manipulators and robotic complexes.
The project team consists of highly qualified specialists in the field of electromagnetorheology who are known throughout the world. It has gained a more than 30-year experience in theoretical, experimental, research and development works in the field of interest in the defence industry, the outcomes of researches are aimed at applications for airspace technologies, ship building, radioelectronics, and petroleum-chemistry industries. The total number of published works of the participators amounts to more than 700, of patents - to more than 200. On the project theme, basic theoretical studies of physics of the ER-effect have been carried out and now experimental measurements of static forces of adhesion due to the ER glue between surface of parts made various materials were on the way. The main factors responsible for magnitude of these forces have been revealed. However, further investigations directed to implementation of the principal concepts of the new technology of fixing of workpieces under machining have been suspended due to cessation of state financing.
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