Transport: Magnetic levitation train places the
highest demands on manufacturing precision
On the world's first commercial transrapid route
sections in Shanghai, the test of the magnetic levitation train
should start at the beginning of 2003. The first of eight track
points is currently being delivered. The contact-free support,
guide and drive system of the magnetic levitation train requires a
precision unusual in steel construction, particularly in case of
points.
The transrapid route section in China will connect
the city center of Shanghai with Pudong airport. At the beginning
of 2003, the 30 km route is supposed to be ready for testing and
will be delivered on 31st December 2003 by Transrapid
International (TRI) to the Chinese operators. The reputation of
German industry is all the more under scrutiny, as these first
reference sections are not within German national boundaries, but
are realized abroad under the eyes of the world.
"We are setting the points for China" asserted Thyssen-Krupp
Stahlbau steel construction with some justification, also in the
literal sense. This is because the points place such high demands
on precision that, without a highly qualified steel construction
company, the whole system would be called into question. To keep to
the tolerances demanded requires not only high-performance
mechanical equipment, but also comprehensive know-how in
measurement and fabrication technology. "Only very few in the world
have these capabilities, and we are proud that we belong to them"
states Johann Matuschek, project manager of the steel construction
firm Thyssen-Krupp Stahlbau.
The transrapid trains move, electromagnetically supported and
guided, at only about 10 mm separation distance from the reactive
spaces of the drive with exactly 2800 mm track width. "The small
space is stabilized continuously with high sequence by the support
and guide magnet" explains Matuschek. In particular, "jumps" in the
support level of more than two tenths would cause the magnetic
regulation to fail under certain circumstances.
If the track already requires small tolerances on free routes, they
must be even tighter in the points; because the branch will be
traversed with 100 km/h speed and in high-speed points even twice
as fast. The magnets must also process the change in direction in
this case, so that inaccuracies must not occur in the track
there.
The track support of the points is bent for the "branching" off
from the straight route by 3.6 m on 78 m length - without
articulated links, only based on the elasticity of the material. A
total of eight points are provided for the system in Shanghai. Each
consists of three 26 m long elements that are bolted together to
form a continuous support. The "dimensional accuracy is 0.2 mm"
Matuschek proudly confirms. Only the blanks were produced in our
own house in this case - even then with high precision. They then
went by low-bed trailer to Hessisch Lichtenau near Kassel, where
the machine shop Richter Maschinenfabrik (guiding principle: "The
Bigger the Better") ensured the final precision.
The high level of precision is necessary above all for the track
underside on which the vehicles "hang" magnetically, and for the
side surfaces on which they are held on the correct path by the
guide magnets. But also the track surface must be absolutely
straight; because the runners glide on that in the emergency case
if the magnetic system should fail: "Maximum admissible parallelism
and angle deviation is < 1 mm with a segment length of 26 m",
stresses executive board member Axel Richter, faced with the
impressive support construction in the gigantic workshop hall.
"Even the room temperature and of course the precise matching of
the temperatures during the standardization of the measuring
equipment play a role in achieving such high precision with
the dimensioning of these parts" reports the company chief, who is
all too familiar with extraordinary dimensions.
Before the actual processing could be begun, every part had to be
aligned exactly: "For this purpose Thyssen-Krupp Stahlbau attached
height and middle incipient cracks in an extremely extensive
optical measurement process, according to which we had to adapt"
states Richter. On the tremendous portal the total of 24 points
segments were then shaped from above and laterally to the correct
dimensions. From the CNC processing center, they would have had to
be conveyed after that and clamped again in order to manufacture
the slot guides and the boring for the non-positive fixing of the
stator blocks, from which the magnetic field originates. At the
support ends the boring was still to be added for the connecting
butt joint.
Today Axel Richter can speak with satisfaction
about these challenges, because his employees have the completed
the work trouble-free - since August 2001 in three-shift operation.
"The management task lay in sensitizing the people there over
periods of months to the precision demanded by these parts" adds
marketing manager Joachim Kraus. For that, the period, which was
unusually long for Richter, offered the possibility of optimizing
the manufacturing sequence and the tool employment. Thus rollover
devices were created especially for the China order, in order to
place the highly elastic supports in front of the CNC processing
center with the required care caution "on the back".
However, the failed Hamburg - Berlin transrapid project also has a
certain benefit for Richter: At that time Thyssen-Krupp developed a
bent points system in Kassel, as it is used now in China. The
company in nearby Hessisch Lichtenau had been linked right from the
beginning for the shaping and grinding work, because a partner with
such impressive capacity would have been difficult to find
elsewhere. The manufacturing know-how prepared jointly at that time
now bears fruit. Last but not least, the China order has been
processed with such impressiveness and the tight time schedule kept
to meticulously up to now.
Source: VDI Nachrichten, Photographs: Ropi
Germany / M. Darchinger
