20 Series Active Vibration Isolation Tables

Transcription

Vibration Isolation Systems Setup Guide, 2014
20 Series Active Vibration Isolation Tables
Introduction
Feature highlights
Compact Sub-Hertz Pendulum (CSPTM) in each leg
Precision Electronic Positioning System (PEPS®)
PEPS-VX® Vibration Cancellation System attached to PEPS.
The table has been assembled at the factory. Leveling of the four CSP
inserted in each leg and tuning of the PEPS/PEPS-VX controllers have been
made and should provide satisfactory performance for a typical installation.
Figure 1, 20 Series Active Vibration Isolation Table
Air supply requirements
The active vibration table requires a continuous supply of compressed air
or Nitrogen to operate properly. For a complete discussion of the air
supply requirements, see System Air Supply Requirements in the
introduction section of this document.
TMC Ametek, Peabody, Massachusetts
Page
WARNINGS
Power Supply
The PEPS / PEPSVX controller does not use a universal power supply.
Country voltage setting The power entry module must be configured
for your country’s voltage as follows.
Remove the fuse access panel (Figure 10) on the PEPS controller.
Remove the small voltage selection card from the module.
Rotate the nylon tab to the correct voltage setting.
Re-insert the card into the power entry module.
Replace the cover. The nylon pin should protrude through a hole
in the cover labeled with your country’s voltage.
Im p o r t a n t The unit is rated for 100, 115, or 230 Volt operations.
The 240 Volt setting should never be used. If you are in a country using
115 Volts, select the 120 Volt setting. Failure to properly configure the
input power module can result in permanent damage to the unit.
Power Cord Use only a UL/CSA/VDE marked mains power cord with
the PEPS controller. The power cord should have at least 0.75mm2 wire
(18 AWG), and include a PE ground. The cord should comply with all
local, regional and national standards for the country where the system is
to be used.
Controller Usage
The controller and its components are only to be used for its intended
purposes described in this manual. Any other usage could jeopardize
operator safety and cause possible injury.
Pneumatic Isolators
Great care should always be used when dealing with pneumatic isolators.
Floating a payload on pneumatic isolators can generate many pinch points.
One such pinch point is between the top of the fixed portion of the isolator,
and the bottom of the ‘load disk’ supporting the payload (see Figure 11).
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Installation and Setup Instructions
Tools Required: 5/32 inch Allen key wrench
Step 1
Install shelf on the frames lower tie bars.
shelf
Figure 2, Table shelf
Step 2
Place PEPS/PEPS-VX controller on shelf.
PEPS/PEPS-VX controller
Figure 3, PEPS/PEPS Controller on shelf
Page
Step 3
Connect cables and tubing
Connect the following from system harness to controller.
1/4 inch OD tubing as labeled.
Connect five 1/4 inch OD tubing from pneumatic system.
Proximity sensor connector
Insert six pin green connector into green receptacle.
Velocity sensor cables
Connect BNC connector cables VS1, VS2 & VS3.
Connect AC Power cord
Ensure controller power switch is in the OFF position
and connect AC power cord.
Proximity
Sensor
Connector
AC Power
Switch
1/4 inch
OD Tubing
Figure 4, PEPS/PEPS Controller cable connections
Page
Proximity sensor
mounted to isolator
Isolator leg
Velocity sensors
mounted under
tabletop
Front
Air supply
Air regulator
adjustment
Waste Air
0utput
Proximity sensor
connector
Velocity sensor
Inputs VS1, VS2, VS3
Figure 5,
PEPS/PEPS-VX Controller connections
Page
Step 4
Connect the air supply
Connect air supply and set air supply and regulator pressure.
For details regarding the air supply requirements,
see System Air Supply Requirements in the introduction
section of this document
Note
Air supply fittings: Tubing can be connected to a 1/4 or
1/8 inch NPT female fitting as shown in figure below.
90-100 psi (621-690 kPa)
Supply pressure or greater above the highest expected
pressure in any isolator when the system is floating.
Air supply pressure
Regulator Pressure 15 psi (100 kPa) or greater above
the highest expected leg pressure.
40 psi is a typical regulator setting for floating the tabletop
without a payload. When adding payload ensure pressure is
increased to 15 psi above expected leg pressure.
1/4 inch tubing
Approx. 30 feet long
Air supply
Adapter
1/4” NPT Male to
1/8 “ NPT Female
Straight Connector
1/8” NPT Thread
Adjust Regulator pressure
Figure 6, Air Supply Connection
Page
Step 5
Center piston assembly
Center each piston assembly on isolator top plate so that
outside circumference of aluminum piston ring aligns with
the edges of three small alignment holes spaced around
piston ring 120 degrees apart.
Piston assembly
Isolator
top plate
Alignment hole
Aluminum
piston ring
Alignment hole
Top View
Figure 7, Centering piston assembly
Page
Step 6
Place tabletop onto frame
Place tabletop down onto frame so that top is centered over
the four isolator legs without disturbing the centering of the
piston assemblies.
Piston
assembly
Figure 8, Mount tabletop
Step 7
Attach velocity sensors
Screw velocity sensors VC1, VC2 and VC3 into bottom of
tabletop as shown in figure below. Connect BNC connector on
end of sensor cable from system cable harness to base of sensor.
VC3
VC2
VC1
Front view
VC1
VC3
Front
Sensor cables
Figure 9, Attaching velocity sensors
Page
Step 8
Float table top
Turn the PEPS/PEPS-VX Controller’s AC Power Switch ON.
Reference figure 10 below.
Expect to hear the sound of flowing air as the four isolators
inflate lifting the tabletop. Once floating you should feel a
spongy action on the tabletop over each of the isolator legs.
ENGAGED
(green LED)
AIR INPUT
from regulator
AUX IN-OUT
DB-25 connector
WASTE AIR
output
Fuse panel and main
voltage selection
ZEROING ON/
ENGAGED
(green LED)
ISOLATOR 1
output to leg 1
AC Power
ISOLATOR 2
output to leg 2
PROXIMITY SENSORS
green input connector
Out of Range
adjust
AC Power switch
RANGE OK
Out of Range/
(yellow/amber LED)
ISOLATOR 3 & 4
output to legs 3 & 4
Clear plastic cover
Figure 10,
PEPS/PEPS-VX Controller
Page 9
Step 9
Adjust "level compensation screws”
Visual check Visually check piston level for each isolator
leg to ensure piston is level with isolator top plate. Only
adjust level compensation if required such as in figure
below showing a slightly tilted piston.
Caution: Keep fingers
away from pinch point
between top plate and
aluminum ring.
Tilted piston and
pendulum tube
Leveling Screw-B
Leveling Screw-A
Isolator top plate
Isolator leg
Figure 11, Centering piston assembly
Adjustments
Center piston assembly over leg by
adjusting each screw as little as possible any one time.
Continue to rotate around table slightly adjusting each leg
until all have been optimized.
Clockwise (cw) turn makes the piston assembly move
away from the screw you are adjusting.
Counter-clockwise (ccw) turn moves the piston
assembly towards the screw.
Move the payload parallel to the screws by adjusting
screws equal amounts in opposite directions.
Move the payload perpendicular to the line between
the screws by adjusting screws in the same direction.
Example: The figure above shows an isolator viewed from
the side requiring a very sensitive adjustment of the
pendulum's level. The pendulum tube is tilted 2.5 degrees.
In this case, leveling screw-A should be adjusted a few turns
clockwise, and leveling screw-B a few turns counterclockwise.
Page
Step 10
Step 11
Add payload to tabletop
Turn OFF air supply and AC power
Place a typical payload onto the tabletop.
Turn ON air supply and AC power to re-float system.
Ensure tabletop is floating without any interference.
Check the following status LEDs
RANGE OK
OFF
Good
ON
Gain settings need
adjusting.
ENGAGE Green LED
ON
Good
ON/OFF Intermittent ON/OFF
Gain settings
need adjusting.
(Ref. “SMART ENABLE”
feature)
Step 12
Excite tabletop with payload
Manually excite tabletop using your hand and observe that
tabletop has a quick impulse response and settle time.
If any of the following conditions are observed then proceed
to the section on “Troubleshooting”.
Poor settle time
Tabletop oscillates
Erratic movements
RANGE OK or ENGAGE LEDS indicate gain settings
need adjusting.
Page
Troubleshooting
Problem: My system doesn't float.
Check power connection, fuse, and voltage setting.
Check power
1) Set DIP switch #5 to ON (right
position)
ZEROING ON LED:
ON indicates power is okay.
2) Set DIP switch #5 to OFF (left
position) once power status is
determined.
Check for air flow: Ensure air supply is
correctly connected.
You can normally hear and feel air venting from the WASTE AIR
output. (reference figure 10).
Air supply pressure: Ensure supply pressure is at least 15psi
(100kPa) above the highest isolator pressure.
Test by increasing pressure.
PEPS-VX Electronic gains:
Increase each gain by 3 CW
(clockwise) turns. Continue to
increase each gain additional turns.
Air lines:
Ensure air lines are
correctly connected, don’t have any
kinks or pinched restricting air flow.
Problem: Some isolators fully inflate, while others get no air.
Air lines: Ensure air lines are connected correctly, don’t have any
kinks or pinched restricting air flow.
Proximity sensors: Ensure sensors are connected correctly, i.e.
proximity sensors 1 and 2 are switched.
Air supply pressure: Increase by 10psi (70kPa)
Pitch & roll gains: increase either gain or both.
Page
Problem: After adding payload to the tabletop my system tilts
back and forth from travel limit to travel limit (unstable in tilt).
System may be gravitationally unstable by sitting on one edge for a while
(up to several minutes), then suddenly `flop' over to the opposite edge. It
will eventually flop back, and repeat the pattern. Any payload supported
under its center-of-mass wants to `fall over'. The isolators provide a
restoring force which resists this from happening. However, if the centerof-mass is too high or the distance between isolators too short, then the
isolators will not be able to keep the payload upright.
The general rule of thumb for stability is:
W2
(H + 0.18m)
> 1.5m
W = center-to-center distance between the isolators
H = height of the center-of-mass.
Borderline systems tend to behave poorly. Some systems which are stable
with mechanical height control valves may be unstable with PEPS.
Mechanical valves act like springs which can help stabilize a system (but also
degrade the vibration isolation). Removing the internal orifices also tends to
make isolators softer, improving performance, but making the system less tilt
stable. PEPS cannot make a mechanically unstable system stable.
Solutions to this problem include the following:
Lowering the center-of-gravity of the system
Increasing the separation between the isolators
Reconfiguring the system so the master/slave legs (legs 3\&4) are
along the long edge of the payload
TMC makes other types of isolators which may improve the
situation, including smaller volume (stiffer) and fluid-damped MaxDamp®
isolators. Contact a TMC sales engineer for more information on this last
option.
Note
Problem: I see some low-frequency noise in the positioning of the
payload which is above the specification.
Water trap Many air compressors cause water to accumulate in
the air lines causing the servo valves in PEPS to work improperly.
Your air supply system should have a water trap. Ensure that water
trap isn’t full.
Page
Barometric pressure
Changes in barometric pressure can also
cause noise on a payload since the sealed chambers of the isolators
make them act like barometers.
Barometric noise Many environments (such as clean rooms) have
very aggressive air handling systems which can generate `barometric
noise'. Likewise, if the system is placed near an air vent, or has some
air circulating about it as part of a `mini environment',
Positioning noise
The table can see excess positioning noise.
These sources of noise are not controllable by PEPS, and must be
addressed at the source. The specification for PEPS was determined
in a sealed room with no air circulation system running.
Problem: The system takes too long to level after a disturbance
(shift in mass distribution).
Like mechanical valves, PEPS is a gain-limited servo. The gain is limited
by the need to preserve vibration isolation in the system. For this reason,
PEPS will level a payload at about the same speed as a mechanical valving
system, depending on the disturbance.
Pitch and roll gains Increase the pitch and roll gains until they are
as high as they can be without the system oscillating. Though this
does hurt the tilt vibration transfer, tilt noise is normally very low in
most environments.
Problem: My isolators inflate to full pressure lifting the payload to
its travel limits, independent of the gain, or even if the power is off.
If the isolators inflate when the power is off, you have probably connected
the air supply tube from the system harness to the WASTE AIR port of the
controller. Recheck the system plumbing.
Page
PEPS/PEPS-VX Controller Advance Setup
Smart Enable The PEPS/PEPS-VX controller is a high-gain feedback
system. To prevent the system from behaving badly when the velocity
sensor feedback is turned on, it uses a “smart enable” feature. The
controller monitors the proximity sensor signals. If the payload moves
more than a few millimeters outside of its normal equilibrium position, the
controller turns off the feedback. Once the payload moves back inside of
its normal operating range, the controller will wait a few seconds, and then
try to re-enable the velocity sensor feedback. The delay allows the system
to stop moving, and prevents the system from engaging on ‘accidental flybys’.
ENGAGED LED (reference figure 10)
ON (green) = Indicates feedback is
enabled. LED turns on when
feedback is enabled and a several
second time delay has passed.
ALL DIP Switch (reference figure 10)
ON (right position) normal operation,
feedback is enabled and ENGAGED
LED lights after several second delay.
OFF (left position) diagnostic mode – feedback is disabled
When setting the gains in the following instructions, be aware of
the ‘smart enable’ function. Ensure the ENGAGED LED is ON when
testing the impulse response. Too hard a push in testing may trigger the
system to disable the feedback momentarily.
Note
DAMPING and ZEROING Gain and DIP Switch Settings
Remove the clear plastic cover on the front
panel (reference figure 10) for setting
Damping and Zeroing DIP switches and
adjusting the controller’s gain settings.
All DIP Switches are set to the OFF position
for normal operation.
Integrator Control: Switches 4 & 5
PEPS/PEPS-VX controller is a sophisticated feedback system which
includes integration as part of its control algorithm. Any error in the
position signals are “integrated” so the feedback to the valves will
Page
continue to change until the error is driven to zero resulting in highly
precise leveling capability. It is not always desirable, however, to have
integration in a control loop.
Under certain conditions, the integrators can ‘saturate’, and require a long
time to recover. For this reason, the integrators can be configured to run in
the following three modes:
1) Integrators ON After Float – Normal mode of operation
As tabletop starts to float integrators turn ON when proximity sensors
detect a payload rise above a preset height. This mode prevents the
integrators from saturating when the isolators are inflating during
power-up.
Switch 4 = OFF (left hand position)
Switch 5 = OFF
ENGAGED LED = ON, Integrators are engaged
2) Integrators Always ON – Diagnostic mode
‘Smart enable’ function is disabled. Integrators are always on forcing
tabletop to float regardless of gain settings.
Switch 4 = OFF
Switch 5 = ON
If the gains are set to low the system may have trouble floating. The
system will take a very long time to come to equilibrium due to the
saturation of the integrators caused during the initial isolator inflation.
This mode is not recommended for a permanent configuration.
3) Integrators Always Off – Diagnostic mode
Setting enables adjusting proximity sensors on a system with very
tight travel constraints in the isolators. It can sometimes be difficult to
locate the ‘operating height’ of the proximity sensors.
When the integrators are OFF the system response is very fast.
Set Integrators OFF
Setting enables adjusting proximity sensors in their brackets to get the
system floating within the mechanical constraints.
Switch 4 = ON
(integrators OFF)
Switch 5 = OFF
Page 1
Set Integrators ON
Set switch 4 to the OFF position. The float height may change a little,
and final adjustments can be made to the sensors.
Switch 4 = OFF (integrators ON)
Switch 5 = OFF
Power-Up Gain Adjustment
The gain of the feedback loops determines the dynamic response of the
isolation system. The following are two responses affected by the gain.
Leveling time The time required for the payload to return to level
after a disturbance.
Level of Damping Determines how quickly the payload stops
moving after an impulse response (also called ‘ring down’ time).
Monitoring gain adjustments
Monitor the response of the payload using the proximity sensor outputs as
follows.
Connect oscilloscope to the three sensor outputs as follows.
AUX IN-OUT, DB-25 Connector
VC1.......... DB-25, pins 7
VC2.......... DB-25, pins 8
VC3.......... DB-25, pins 9
GND ......... DB-25, pins 23-24
Set oscilloscope
Vertical direction............ v/div
Horizontal direction ....... 0.5 s/div.
Figure 12 below shows examples of the impulse response for
different gain settings.
TMC offers a ‘breakout box’ to make connections to DB-25
connector easier for OEM customers.
Note
Page 1
Setting Gains with Electronic Damping
Every system is tested at the factory and the gains are set to values which
will allow the system to float.
Height Gain Adjustment
Turn power ON.
Connect an oscilloscope as follows.
AUX IN-OUT, DB-25 Connector
Height analog output ........ DB-25, pin 4
GND ................................. DB-25, pins 23-24
Press down lightly on the center of the payload, and you should see
a response on the scope.
Turn the gain down until the response looks like the left-hand curve
in figure 12 below.
Gradually increase the gain until the oscillatory behavior is
suppressed (the right-hand curve below).
Pitch and roll gain adjustment
Repeat above procedure by moving the scope to the proper pin on
the AUX IN-OUT, DB-25 connector each time.
Excite the payload by pushing it sideways.
Figure 12, Damping Too Low and at Optimum
Do not set the gain any higher than is required to damp the motion.
Figure 12 above shows what happens when the gains are increased too
much. Notice that the pitch and roll degrees of freedom may not have as
high a damping level as shown in Figure 13. If this is the case, then
increase the gain until the damping of the primary oscillation stops
improving.
Page 1
Figure 13, Gain Too High With Electronic Damping
Figure 13 above shows what happens when the gain setting is set too high.
The oscilloscope sensitivity has been increased to 100 mV/div. Notice that
system has gone into a sustained oscillation at approximately 7.5Hz.
Too Much Gain?
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Page 1
Figure 14, Vibration Transfer and Impulse Responses for Different Gains
TMCAmetek, Peabody, Massachusetts
Page
“RANGE OK” LED – The PEPS Go-No-Go Indicator
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Page
PEPS Technical Specifications
Quoted technical specifications are typical values, and not a guaranteed
performance level. They are subject to change without notice.
Power Supply ....................................................... 100/115/230 VAC, 50/60 Hz, 20W max
Fuse .......................................................................................... T 0.25 A, 250 V slow-blow
Power Cord ..................... UL/CSA/VDE marked 0.75mm2 wire (18 AWG) w/PE ground
Air Consumption ............... 45slpm (1.5 scfm) dry, clean air, filtered to 20μm or better
Maximum Air Transfer Rate .......................................... 15slpm (0.5scfm) (Per isolator)
Leveling Accuracy ................................................. 5μm height, 5 μradian pitch and roll
Leveling Hysteresis (integrators on) ................... 5μm height, 5 μradian pitch and roll
Leveling Hysteresis (integrators off) .............. 50μm height, 50 μradian pitch and roll
Physical Dimensions ................. 165mm (6.5”)H x 104mm (4.125”)W x 190mm (7.5”)D
Weight (unit alone) ................................................................................. 2.51 Kg (5.52 lb)
Standard Proximity Sensors ......... Turck Ni15-G30-Y0 NAMUR eddy-current sensors
................................................................................................... (15mm operating height)
Proximity Sensor gain ...................................................................................... 2volts/mm
Environmental
For indoor use only, up to an elevation of ............................................ 2,000m (6560ft.)
Temperature range .......................................................................................... 5C to 40C
Humidity range 80% up to 31C, decreasing linearly to 50% relative humidity at 400C
Tolerance in mains supply voltage ....................................... +/-10% of nominal voltage
Installation Category ....................................................................................................... II
Pollution Degree ............................................................................................................... 2
AUX I/O, DB-25 Connector (colored ribbon cable)
Pins
1)
2)
3)
4)
5)
6)
7)
8)
9)
10)
11)
12)
13)
Pins
Height Feed-Forward Input
Roll Feed-Forward Input
Pitch Feed-Forward Input
Height Analog Output
Roll Analog Output
Pitch Analog Output
Prox. Sensor (1) Output
Out of Range Logic Out
Out of Range Voltage TP
+15 EXT. Power Input (750mA max.)
-15 EXT. Power Input (100mA max.)
14)
15)
16)
17)
18)
19)
20)
21)
22)
23)
24)
25)
Valve (1) Test Point
GROUND
GROUND
GROUND
GROUND
GROUND
GROUND
GROUND
GROUND
EXT. Power Ground
Figure 15, PEPS technical specification
Page
PEPS-VX Technical Specifications
Quoted technical specifications are typical values, and not a guaranteed
performance level. They are subject to change without notice.
Physical Dimensions (VX Controller)165mm (6.5”)H x 46mm (1.8”)W x 190mm
(7.5”)D
Physical Dimensions (w/PEPS) ..... 165mm (6.5”)H x 153mm (6.0”)W x 190mm (7.5”)D
Velocity Sensors .............. 90mm (3.53”)H x 44mm (1.7”) Diameter “geophones” with
.......................................................................... BNC connector & ¼”-20 Mounting Stud
Weight (PEPS-VX Controller) ................................................................. 1.37 Kg (3.02 lb)
Leveling Accuracy ............................................. 20μm height, 20 μradian pitch and roll
Leveling Hysteresis........................................... 20μm height, 20 μradian pitch and roll
Environmental
For indoor use only, up to an elevation of ............................................ 2,000m (6560ft.)
Temperature range .......................................................................................... 5C to 40C
Humidity range .................................................. 80% up to 31C, decreasing linearly to
......................................................................................... 50% relative humidity at 400C
Installation Category .......................................................................................................II
Pollution Degree ............................................................................................................... 2
AUX IN-OUT DB-25 connector (probe test point locations) and
TO PEPS
DB-25 connector (with colored ribbon cable)
Pin
1)
2)
3)
4)
5)
6)
7)
8)
9)
10)
11)
12)
13)
Pin
Height Feed-Forward Input
Roll Feed-Forward Input
Pitch Feed-Forward Input
Height Analog Output
Roll Analog Output
Pitch Analog Output
Proximity Sensor (1) Output
Out of Range Logic Out
Out of Range Voltage TP
+15 Ext. Power Input (750mA max.)
-15 Ext. Power Input (100mA max.)
14)
15)
16)
17)
18)
19)
20)
21)
22)
23)
24)
25)
Height Test Input
Height Test Output
Roll Test Input
Roll Test Output
Pitch Test Input
Pitch Test Output
GROUND
GROUND
EXT. Power Ground
Figure 16, PEPS-VX technical specifications
Page
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20 Series Active Vibration Isolation Tables

Transcription

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