|There is a technology which draws the attention
of world carmakers..
That is the transmission shaft developed by Kubota Iron Works
Co., Ltd., which engages in manufacturing automotive components.
Kubota implemented the first one-shot press forming from
5 directions in the world, and succeeded in weight reduction
and cost reduction by simultaneous forming of the external and the internal hollow structure.
Various industries such as aircraft, shipping, and agricultural
machines have shown interests in the new method generated
by skilled die technology.
A man looking at a shaft curiously started to talk with an
" How did you make it? Please show me the dies which manufactured
At an automotive component manufacturer's technical exhibition
held in Nagoya last October, these kinds of questions were
repeatedly asked at the booth of Kubota Iron works Co., Ltd.
The exhibited product was a transmission shaft sectioned
to show the internal hollow structure, which is expected
to put to practical use shortly.
Already decided to supply.
The transmission shaft is an axis binding several gears
and its standard size is approx. 12cm maximum in diameter,
and approx. 60cm in length.
The weight of major manufacturer's existing shafts is approx.
Kubota's shaft is approx. 4 kg, which is lighter by
more than 30%.
Total number of inquiries has reached about 10 companies.
Mr. Shigeaki Yamanaka is surprised at the market responses
being beyond expectations, and he commented that until
now, we have visited customers for the sales of our products,
however, now customers visit us.
Conventionally, for making a hollow shaft, the external
is pressed first, and then the internal is drilled by a
separate machine. In order to form it with one machine
at one time, the press from 5 directions is required. No
one until now has implemented the one-shot press from 5
directions although it is conceptually conceivable.
In which order and pressure will 5 dies be pressed for
The person who developed the complicated die movement was
a veteran engineer in his seventies and he is called "Human
Mr. Yamanaka, Director looks back that a veteran engineer's
long experience for dies created the idea of the complicated
die movement.(although the detailed process is confidential.)
Challenge for survival
Kubota's main product is steel water pumps that cool the
However, in the 1990's, Kubota anticipated the risk that
the cost of machining requiring a lot of difficult processes
for automation would not be competitive against those of
China or South Asian countries.
As a survival measure that Kubota's original die technology
can be utilized, Kubota focused attention on cold forging
which forms metals by high pressure in normal temperature.
Cold forging is the first field for Kubota. In 2002, Kubota
established a Research association of 11 automotive component
manufacturers having business relations in Hiroshima and
researched the basic technology.
Cold forging needs complicated processes to secure high
accuracy and it becomes more difficult when the press directions
Kubota focused on weigh reduction. Carmakers are in fierce
competition for fuel consumption improvement and exhaust
gas reduction under the circumstances of fuel price increase
or eco-consciousness enhancement. If the vehicle weight
is reduced, fuel consumption is improved, and exhaust gas
is also reduced. Mr. Yamanaka was confident that weight
reduction of metal parts would expand the uses.
The press from 5 directions enabled one process forming
in 18 seconds, with the internal hollow forming within
one process. Furthermore, as the largest hollow can
be formed, the weight is reduced drastically.
For Kubota's shaft, aircraft related industry's engineers
and shipping & agricultural machine makers also indicate
interests. Kubota is going to expand the application to
other components than automotive components in the future.
Kubota has found new possibilities of metal shafts by
utilizing metal forming experience of more than half-century.