Every even year (when EMO exhibition is not organised) the International Machine Tool Exhibition - IMT - is held in the Czech town of Brno. Even if it has an affluent attendance of leading European and worldwide producers, it is above all a prestigious event for domestic manufactures. They want to present their best and thats way IMT is full innovations and world first presentations of often unique Czech machine tools. One discovered a series of novelties at the last IMT Brno 2002 as well. Featured here is a brief background of four increasing machines that originated at development shops of Czech companies and that were shown at the exhibition centre.
Kovosvit MAS and Unconventional Kinematics
The Kovosvit MAS, ajoint stock company at Sezimovo Usti, came with a completely unique solution of a horizontal machine centre, called TriJoint 900H. It is based on absolute new kinematics of the tool module in the X-Y axes plane so far unconventional in mechanical engineering. Despite the fact that it is a very advanced solution, Kovosvit MAS wants to start series production of TriJoint 900H machining centres very early. TriJoint 900H should be mainly used in4he aircraft and automotive industries and in the large-lot and mass productions. It is very well equipped for this application. The designers tried to adapt technology sequencies to user needs as much as possible. Thats why the exchangeable pallets are equipped with energy supplies (electricity, hydraulics, compressed air) that are transferred along with their clamps from one pallet position to another. In this way it is possible to machine without idle times, which means in highly productive times.
A similar tool kinematicssolution, that features TriJoint, can boast only two subjects in Europe today-Kovosvit MAS and a German company Huller Hille. Vladimir Eizek, Director of Technology in Kovosvit MAS, says "One of the problems we encountered was legal patent collision between Huller Hille and our solution of kinematics. After a detailed analysis it came out that Huller Hille had patented only one concept from the whole new machine series, meanwhile Kovosvit MAS patented the whole series and TriJoint is situated outside the patent concept of Huller Hille. It is true that the German producer developed a machine concept based on a similar kinematics
structure, but according to our view it could not make the best of the potential of the new solution.
"Unlike the TriJoint centre, all the developed machine with parallel kinematics worldwide can boast ahigh dynamics but at the same time they possess lower rigidity and lower natural frequency. We were successful in overcoming these limitations and we are the first producer in the world that managed to boost both dynamics and rigidity of the machine. Just the totally rigid structure is very important so that high dynamics can be used at all. TriJoint showed for the first time ever that parallel kinematics makes it possible to move all utility features of the machine to higher values."
TriJoint is designed as horizontal type of machine: ie, it has a rotating pallet that moves in Z axis (forward-backward) and further there is a plane from which it executes cutting (X,Y axes). It has four working axes (pallet rotation, pallet in-feed, X and Y axes) and four degrees of freedom (it is based on a planner kinematics mechanism principle that has two arms and three joints). The most important task in designing the machine was to turn the calculated and optimised parameters in the real practice.
Basic technical specification of TriJoint 900H : Scope of travels in X/Y/Z axes - 900/700/750 mm, rigidity in X/Y/Z axes - more than 100 N.um" spindle motor output SI/S6 - 25% - 28/32 kW, maximum torque S I/S6-25%- 67/76 Nm, maximum spindle speed - 24,000 rpm, spindle taper - HSK-A63, Sinumerik 840D controlsystem, pallet clamping face - 630 x 630 mm, maximum workpiece weight - 700 kg, pallet exchange time - less than 10s, speed of the rotary axis -65 RPM, and machine weight - 22,000kg. The machine can be equipped with as much as three magazine modules, each having 48 positions. It is very important technology aspect that makes it possible to use TriJoint in flexible production lines where it is necessary, at incessant changes in production programmes, to have a great number of tools in stock.
One of the most admired machines at the 2002 International Machine-Tool (IMT) Exhibition in Brno was an unconventionally designed machining centre called Tummill 1250 produced by Tajmac-ZPS Zlin. The history of its development is clarified more closely by Pavel Slama, senior designer of machining centres at Tajmac-ZPS : "Several years ago our company went through a very complicated stage of restructuring; it was necessary to safeguard continuation of development and production of our own machine-tools and to enter on new markets. In this difficult time we developed and manufactured a machine of new conception, so called upper gantry-Depocut 2012. Even if this type of equipment we do not produce any more, at that time we obtained a lot of knowledge and experience from development and production and also know-how in design. These were reasons for the company management to decide to continue efforts, after several years, in the given direction and to complete technology with turning and grinding operations to get to the level of vertical middle-sized lathes."
"It gave rise to preparation of a project of multifunctional machine in the size of a gantry-type vertical machining centre called Turnmill (turning and milling) 1250/2000 (according to clamping table size). Immediately a relatively large marketing research followed aimed mainly at component part producers for aircraft (suppliers of sophisticated parts of aircraft jet engines), crude oil and energy industries. The purpose of the research and the simultaneous project acquisition was to offer a machine the technology of which makes it possible to finish very elaborate parts at one working place in one setting and can replace three and more expensive single-purpose machine.
Tummill, in its basic design, is a four-axes table that balances the main cutting motion during turning and enables automatic change into a mode corresponding to a secondary motion during milling and horizontal cutting, as a full C-axis enabling very precise (up to 5 arcsec) peripheral milling with interpolation to other axes. The machine is able to use the most advanced cutting tools.
Focus on Safety Standards
Concerning innovations at TOS Ku0im - OS, a joint stock company, Jan Sobol, development department head of general-purpose machine, had this to say: "This year we are exhibiting a machining centre of new generation denominated FFQ I OO A. On its basis, a complete module system has been created that, at retaining basic elements formed by stand, bracket, headstock, and exchange heads with automatic tool exchange, makes it possible to innovate our current machine programme, known as FS and FU series. Our primary intention is to secure competitive advantage concerning functionality, versatility, design and price. The new FFQ I OO A, a milling centre with a movable stand was developed at TOS KiiOim- iisine technology nossibilities of The Engineering us i\.ui6ini, using recnnology pUbiiiDiiilica ui inc E,iigjnccniig Technology Research Centre at EVUT Prague and we collaborated also with VUT Faculty of Mechanical Engineering in Brno. One of the main parts of FFQ 100A is a firm table next to which a stand is moving. On the vertical stand guide moves a bracket and in its transversal guide moves a headstock. The machine is equipped with a horizontal headstock that has either a steady i-built head or a mechanism for automated clamping of exchangeable milling heads. The main structure elements of the frame are optimised with regard to safeguarding high dynamic and static rigidity. And all that at respecting demands concerning minimisation of movable weights. Thus we could reach at FFQ 100 A feed rates of 20 m/min in linear axes at acceleration of 2 m/s2.
FFQ 100 A Centre is also equipped with thermal stability of headstocks and spindle heads. This design, in connection with double drive of the vertical axis, makes it possibleto compensate the exit of the horizontal ram. The customer can, in the basis offer, choose among 8 types of exchangeable spindle heads. For selection there are heads both for heavy-duty machining with a maximum spindle torque of 2,000 Nm at 4,000 RPM, and for high-speed machining at 18,000 RPM and 100 Nm torque. The exchangeable heads are positioned in a modular magazine that enables automatic handling. The headstock is furnished with an automatic mechanism for gripping and positioning of heads including transfer of necessary energies.