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The Speedy Rail® shuttle bars are light aluminium alloy profiles that are treated in order to have high resistance to wear and alloy profiles that are treated in order to have high resistance to wear and to welding splatters:
The roller assemblies are self-aligning to obtain a uniform distribution of the loads on the rollers. The rollers are coated with a plastic compound in order to obtain low operating noise and to avoid wear on the shuttle bars. The bearings inside the rollers are "lubricated for life" with a special synthetic grease for a life of at least 10 years. The machines are composed of modular elements which are pre-assembled before shipping in order to limit assembly work on site. Actually the assembly operations are extremely simple and can be accomplished in a short time. The only thing required in order to join the modular mechanical components is a small number of screws. As an example, the assembly of a 10 station transfer line (total length 70 m) takes only 1 working week of 4 workers. The precision of the manufactured parts and their assembly assures perfect machine geometry; this is the main condition to avoid overloads on mechanical parts and excessive power absorption by the motors. During final assembly, the T.M.T. modular concept avoids the use of optical instruments. The T.M.T. modular elements have a reference for perfect auto-alignment with precision better than 0,1 mm. The control system allows the cycle times, accelerations and deceleration rates to be changed quickly and easily. This adds flexibility of use to the transfer lines. The geometric concept of T.M.T. transfer lines allows them to be driven by mechanical speed variators with asynchronous motors without any problems. Normally the lifting is achieved through articulated levers connected by draw-bars. When there are space problems it is possible to obtain lift movements through vertical – excursion – racks, connected by draw-bars. The horizontal movement is achieved by the rack and pinion method using gear boxes and brushless motors. For protection from damage due to accidents, T.M.T. transfer lines are equipped with mechanical torque and load limiters in addition to electrical stroke limit switches. On the shifting drive there is steel busing with a calibrated hydraulic expansion control. The lifting is provided with a traction and compression limiter. The balancing of the lifting load is normally achieved with hydro-pneumatic balances. The dimensions of a transfer line "Lift & Carry" make it uneasy to present it at an exhibition; therefore T.M.T. has fitted an open-house in its workshop in Piacenza, in order to give to the customers and to all interested people the possibility of examining a functioning system. It is a 5 station transfer line "Lift & Carry"; each station has a 6 meter stroke and the line carries 4 complete bodies of BMW model series 3, kindly given to T.M.T. by the Munich automobile house. The total length of the line is of 36 meters and the cycle-times are among the shortest ever obtained: only 3 seconds for a 6 meter sliding. Thanks to this display T.M.T. can give to its customers the possibility of examining each constructive detail and the performances of its lines. As all T.M.T. transfers, also the display line is provided with manual motion systems for emergency situations, and precisely, oleo-dynamic cylinders that can be easily connected to each lifting unit and are driven through flying electro-hydraulic plants. Thanks to these systems the lifting of each station can be controlled manually, independently from the others; it is also possible to control more than one station at the same time. Also for the horizontal movement there is the possibility of a manual control through a crown-wheel. These manual devices are extremely useful during the assembly of the line, the maintenance operations and to make sure that the production continues also in case of failure of motors or drives. For obvious reasons this last opportunity is highly appreciated by the customers. T.M.T. is glad to organise a visit to its open-house for interested customers. Photo N° 1: Transfer Line S319 (Display Line) Photo N° 2: S319 – Details of the drive for the horizontal traverse Photo N° 3: S319 – Hydraulic gears and cylinders for the maintenance and emergency drive of the lifting (red painted) Photo N° 4: S319 – Hand-wheel for manual drive of the horizontal traverse during the maintenance and the emergency operations TMT SUCCESS IN 2004 TMT planned, built and installed a lift and carry transfer line with exceptional length and load capacities for a car constructor in China. This transfer has 14 stations for a Respot welding plant. Pitch among stations is 6 meters and as a consequence the length of the line included the dimensions of the drive unit of vertical movement is 92 meters. The load to be carried is 510 kg. per station for a total weight of 6.630 kg. as car-bodies lifted by shuttle bars are 13. The lifting stroke is 600 mm and takes 4 seconds while the horizontal stroke is 6000 mm and takes 10 seconds. Both shuttle bars are composed by two light alloy profiles Speedy Rail SR250 with surface hardened at 700 Hv. Line doesn’t practically need maintenance as all moving components have a lubrication for life. Positioning accuracy is + 1 mm. Both shuttle bars and lifting mechanisms are equipped with adjusting systems to compensate linear expansions due to seasonal temperature changes. In spite of the exceptional length and the big carried weight, the line is moved by two drive units: one for vertical movement placed at one end of the line and the other one for horizontal movement placed between the forth and the fifth station. Motors are equipped by absolute encoders and are fed by digital controls. Line works automatically and is interfaced with the welding plant through a field bus. Test and production starting have been carried out at the beginning of May 2004 with very satisfactory results. Such an important achievement doesn’t belong to everyday life and represents a positive demonstration of the high specialization level reached by TMT.
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