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Grinding wheel dressing

VIEWS: 139 PAGES: 4

									                                                                           IOP
                                                                           Precision Technology


Grinding wheel dressing

Dressing of super-abrasive grinding wheels
 Subject:                                                                                              Grinding has always been one of the most precise
   Dressing of super-abrasive grinding wheels                                                          manufacturing processes. With the appearance of hard metal,
                                                                                                       ceramics and glass, it has become even more important as a
 Purpose:                                                                                              machining method. However, these extremely hard materials
   To develop a flexible dressing tool and method for super-abrasive grinding                          demand very special grinding tools. Therefore super-abrasives
   wheels (accuracy to 1 µm)                                                                           such as diamonds and cubic boron nitride grains are used in
                                                                                                       the grinding wheels. But these tools are extremely difficult to
 Market application:                                                                                   prepare. Researchers at the Delft University of Technology are
   Tool shops, manufacturers of grinding wheels and grinding machines                                  working together with the Energy Research Centre of the
                                                                                                       Netherlands to develop a flexible method to dress super-
 Potential use:                                                                                        abrasive grinding wheels. Dressing includes profiling and
   Fast and flexible dressing (profiling and reconditioning) of grinding wheels,                       reconditioning of the grinding wheel circumference. ‘How can
   for small batch production                                                                          you shape a grinding wheel when it is already composed of the
                                                                                                       hardest material available?’
 Research period: August 2003 - August 2007
                                                                                                       ‘Industry is using ever harder abrasives in grinding wheels, like
 Budget: EUR 484,000, of which EUR 358,000 funded by IOP                                               diamond and cubic boron nitride’, says André Hoogstrate,
                                                                                                       Assistant Professor of Production Technology at the Faculty of
 Research institutes: Delft University of Technology, Energy Research                                  Mechanical Engineering. ‘The trick is to find a way of giving
   Centre of the Netherlands                                                                           these tools their shape. This is not only a problem for
                                                                                                       manufacturers of grinding wheels; over time, these wheels wear
 Project leader:André Hoogstrate                                                                       in use, and have to be dressed. Preferably on the machine, without
                                                                                                       the need to take them off.’ Conventional ways to reshape grinding

 Project team, Delft University of Technology. From left to right: Jaco Saurwalt (ECN), André Hoogstrate, Jeroen Derkx, Bernard Karpuschewski, Bas Wardenaar (ECN)
 wheels are single-point diamond dressing or the use of diamond
 form rollers and profile rollers. ‘But either these methods cannot
 be used for super-abrasive materials, or the wear of the tools is
 extremely high’, adds Jeroen Derkx, the PhD student conducting
 the research for this project in Delft. ‘Other disadvantages are in
 some cases their inflexibility and high cost. Therefore these
 dressing methods can only be used economically in mass
 production. In this project we aim explicitly for their use in small
 production volumes. But the ultimate question is: how can you
 shape a grinding wheel when it is already composed of the hardest
 material available?’ The project team identified the principle of
 crushing as a promising method.
                                                                                          Grit break-out in crushing process (according to Hessel)
Crushing
 ‘When you use crushing as a way of profiling a grinding wheel, a                           to do research on this subject’, says André Hoogstrate.
 rotary dressing tool is pressed against the rotating grinding                              ‘It combined well with the work on crushing that Professor
 wheel. This tool will then spin with the same speed as the                                 Bernard Karpuschewski had done previously in Germany.’
 grinding wheel’, explains Jeroen Derkx. ‘So the relative velocity                          ECN knew companies which would be interested in solving the
 between the dresser and the wheel is zero, and there is mainly a                           problem of dressing super-abrasive grinding wheels: tool shops
 normal force.’ This force causes the binding material which holds                          and manufacturers of grinding machines and wheels. Jeroen
 the abrasive grains together to break, thus making the grains drop                         Derkx: ‘Tool shops are potential buyers of the dressing method
 out. Obviously dressing wear will be much less, because the                                that we want to develop. Their tools wear with use, so in order to
 diamond particles themselves are not machined, rather the                                  keep grinding with high accuracy, they need reshaping. A device
 material which holds them. A prerequisite is the use of a brittle                          with which they can dress grinding wheels on the machine,
 binding material. Finding the right grinding wheel composition is                          without the removal of the wheel, would be most welcome. These
 crucial: the wheel must be adapted to the actual grinding                                  people can tell us exactly what the problems are, what kind of
 operation, and it must allow crushing as a way of dressing it.                             profiles they need to dress, the required accuracy at this point in
 ‘These conflicting demands on the dressing of the wheel and how                            time, and their expected needs in a few years.’ There are no
 the wheel behaves in practice make the world of grinding so                                manufacturers of grinding machines and of super-abrasive wheels
 complex’, says Jeroen Derkx.                                                               using brittle binding materials in the Netherlands. To further
                                                                                            identify their needs, relations have been established with several
Cooperation                                                                                 companies in Germany.
 The IOP project is a cooperation between the Delft University of
 Technology and the Energy Research Centre of the Netherlands                             Industrial involvement
 (ECN). The latter’s Technology Services and Consultancy                                    During the first year of the project, Jeroen Derkx has oriented
 division is one of the most experienced groups in the Netherlands                          himself on the market, the technology and the scientific
 on the subject of grinding special materials in small series, for                          knowledge on the subject of dressing grinding wheels.
 instance ceramics used in the area of fuel cells. ‘It was their idea                       Furthermore, he has conducted initial experiments to determine
                                                                                            the demand on the dressing device to be developed. He is
                                                                                            currently working on a more accurate problem definition and is
                          Detail of the crushing process; top right, the grinding wheel
                                                                                            identifying which steps in the crushing process are the most
                                                                                            crucial. In the next phases he will do further research on the
                                                                                            process itself and work on a design for a crushing device,
                                                                                            including its bearing, and the propulsion of both the grinding
                                                                                            wheel and the dressing tool to minimise friction. Also important
                                                                                            is the extra swivelling axis that increases the flexibility and
                                                                                            quality of the produced profiles.
                                                                                            Once the IOP project is finished, ECN will further develop the
                                                                                            dressing method into a marketable product. Through the contacts
                                                                                            with companies in the industrial user group, a party will be
                                                                                            sought to introduce it on the market. Interest in the subject is
                                                                                            high, as is evident from the list of members of the industrial
                                                                                            user group.
                                                                                            ‘Our moulds are mainly machined by grinding’, says Gerrie
                                                                                                          Setup for experiments on crushing


                                                                           in touch with the area of precision technology. When he heard of
                                                                           this dressing research proposal, he introduced the team to
                                                                           potentially interested companies. The IOP invited him to take a
                                                                           seat in the industrial user group. ‘Technology has always
                                                                           interested me. When I retired from Philips, I wanted to stay active.
                                                                           Together with Jeroen Derkx we visited tooling shops and with
                                                                           Professor Bernard Karpuschewski we did a tour in Germany. Now
                                                                           we meet several times a year to discuss results and give input.’

                                                                          Members of the industrial user group
                                                                           Besi Tooling
                                                                           De Ridder
                                                                           Jos van den Biggelaar
First design of proposed dressing tool                                     Philips Enabling Technologies Group
                                                                           Saint-Gobain Abrasives
 Peters, tool shop manager at Besi Tooling. His tooling department         SMS Gereedschapmakerij
 is responsible for the moulds in which ICs are encapsulated in a          Technodiamant
 thin layer of plastic. Another Besi company, Besi Moulding                TSD
 Systems, builds the machine which puts the ICs into the moulds            VDL Gereedschapmakerij
 and does the actual injection moulding. ‘It’s a fiercely competitive
 area, and we are always aiming to produce our equipment in a             Contact information on Grinding wheel dressing
 more efficient and therefore cost-effective way. We are interested        Delft University of Technology, Faculty of Mechanical Engineering
 in finding smarter solutions to making the profiles in the moulds.        Dr ir André Hoogstrate, Assistant Professor of Production Technology
 Is it possible to grind several profiles in one go? Which materials       Telephone +31 15 278 68 04
 are useful?’ It is the first time that Gerrie Peters has been involved    E-mail      a.m.hoogstrate@wbmt.tudelft.nl
 with an IOP project. He finds the meetings of the industrial user         Website     www.wbmt.tudelft.nl/pto
 group useful in several ways: ‘Our company was too introvert in
 the past. Now we meet other parties, and I find the discussions          Project team on Grinding wheel dressing
 open and spontaneous. The contact with the university has grown           Jeroen Derkx
 more serious. And by changing the meeting venues, we can all              André Hoogstrate
 visit the other companies which have joined the industrial user           Bernard Karpuschewski
 group.’                                                                   Jaco Saurwalt (ECN)
 After Jos van den Biggelaar retired from Philips, where he was            Bas Wardenaar (ECN)
 responsible for investments in universal machining tools, he kept
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   Colophon

   This is a publication of SenterNovem                                                          The project on Grinding wheel dressing is conducted in the Faculty
   October 2004                                                                                  of Design, Engineering and Production of the Delft University of
                                                                                                 Technology in close cooperation with the Energy Research Centre
                                                                                                 of the Netherlands (ECN).
   SenterNovem The Hague
   Juliana van Stolberglaan 3
   P.O. Box 93144
   2509 AC The Hague                                                                             The Energy Research Centre of the Netherlands (ECN) develops
   The Netherlands                                                                               technologies for a safe, efficient, reliable and environmentally
                                                                                                 benign energy supply.
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