Apr 15, 2015
Newly developed automotive motor shaft, with half the weight of conventional products
Akiyama Manufacturing, with support from the Japanese Government, has developed an automotive motor shaft that weighs half as much as conventional products, by utilizing a hollow structure.
"One big feature of this product is, it weighs about half as much as conventional versions. It utilizes conventional materials and designs, but we’ve eliminated material inside, to make it much lighter than ordinary shafts."
The newly developed shaft is manufactured by joining three items using friction pressure welding. Previously, this method had very low joining precision, which resulted in vibration due to poor dynamic balance. Consequently, the method wasn’t practical for motor shafts. But now, Akiyama’s unique friction pressure welding technology has enabled joining to be achieved with very high precision, to below 0.05 mm.
"With this shaft, we guarantee such good balance, there’s no vibration even at high rev rates in excess of 10,000 rpm. We’ve also built a measuring device for this ultralight shaft. This machine can check easily whether the shaft is in balance, so we’ve used it while developing the shaft. Even in mass production, we can provide a product warranty using the measuring device, so we have confidence in this regard."
Making the shaft lighter enables a motor’s inertia to be minimized. So, this shaft could also enable motor responsiveness to be improved. In addition, the new technology guarantees sufficient strength to handle high torque, which is essential in motor shafts, while also achieving lighter weight.
"Regarding strength, we’ve also built nondestructive measuring devices to guarantee the shaft’s strength. Specifically, we use acoustic emission to check for internal defects, and ultrasound to check for internal gaps. In this way, we’ve achieved a warranty system."
Akiyama has already supplied prototypes to Japanese automakers, and aims to release a commercial version in Japan around 2018. Subsequently, the company envisages supplying shafts to North American automakers, which use larger motors.
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