Subject: TAKENAKA
Date: Thu, 20 Jan 2000 18:52:53 -0600
From: "Imafuku, Nobuhiro" <Nobuhiro.Imafuku@mts.com>
To: "Rood, Omar" <Omar.Rood@mts.com>, "Larson, Rod" <Rod.Larson@mts.com>
CC: "Katabami, Yoshihiro" <Yoshihiro.Katabami@mts.com>, "Otsuka, Yutaka"
     <Yutaka.Otsuka@mts.com>

Hello, OMAR & ROD san.

1.      We have a big trouble. When we apply $B!H(JLOW$B!I(J pressure, actuator
suddenly goes unstable (oscillation problem) but this happens only
couple seconds (see enclosed Oscillation Data file) and goes stable. We
check follows (we always enable limit, so that table and actuator have
no damage). Once we apply $B!H(JLOW$B!I(J pressure and then $B!H(JHIGH$B!I(J pressure,
we do NOT have any oscillation problem until hydraulic off. We assume
this is caused by air like NIED prototype table but we are NOT sure.
Please advise how check this trouble more and please send two slow turn
on accumulators for HSM urgently.
1)      At first, we check HSM and we found two slow turn on
accumulators for 100 ton actuator are broken (we can NOT charge N2 gas).
2)      We check servo valve with pilot pressure only and maximum spool
position is set about +/- 2V. Normally, we set this value about +/- 6 -
+/- 8 V. We think this value is quite low. Is this normal value if we
use TestStar IIs ?
3)      We apply 210 kg/cm^2 pressure and push $B!H(JLOW$B!I(J using two HSM.
Actuator suddenly goes unstable and stops because exceeding limit (we
have no damage on table and actuator due to enable limit). At this time,
displacement gain is 1 and control mode is displacement.
4)      We use two HSM and apply 50 kg/cm^2 pressure. When we check at
displacement gain 1 on displacement control mode, actuator goes
unstable. Then we decrease gain step by step, actuator oscillation stops
at displacement gain 0.07 but actuator slightly moves.
5)      We use two HSM and apply 210 kg/cm^2 pressure. Actuator does NOT
suddenly unstable but actuator slowly moves and stops about middle
position.
6)      Then, we change acceleration control mode and tune system (we
still have same problem when we apply $B!H(JLOW$B!I(J pressure).
2. We are possible to connect all hoses now for 100 ton actuator (two
HSM sit actuator right side and other two HSM sit actuator left side).
When we apply pressure, we have too much flow and high pressure
sometimes does not reach 210 kg/cm^2. If we ignore low pressure
adjustment, this flow stops. Do you have any idea to adjust four HSM
working correctly ? 50 ton actuator looks OK.

I tried to send this mail yesterday but our server was down and I could
NOT send. Please reply by return.

 <<Oscillation Data.xls>>

REGARDS     FUKU

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