Screening Services and
Training
Last Update 10/06/2005
25092 Natama
Ct
Based upon a procedure written by Screening
Systems, Inc.
Laguna Hills, CA 92653-5607
How to: Balance QRS Type Vibration Tables (B-100 or RVP-100
Controllers)
This procedure applies to systems manufactured by Screening Systems,
Inc. that use B-100 or RVP-100 vibration controllers.
The purpose of this procedure is to explain how to balance the
vibration controller parameters of a type QRS vibration system such
that each vibration pneumatic channel (Valve Channel) contributes an
equal amount of energy to the vibration table or a product mounted on
the table.
Perform the following procedure:
1. Mount the feedback accelerometer clusters at
locations
that will be close to any product fixtures that may be used while
remaining clear of possible damage caused by product or fixture loading
and unloading. Typical locations would be a couple of inserts
in
from the left and right edges near the rear of the table.
2. For a table with a product mounted in a fixture,
mount a
product response accelerometer on the fixture or at a location near the
center of the product, on solid structure if available, or near the
center of a printed circuit board and perpendicular to its plain.
3. Place the controller in MANUAL mode.
Set the Vibration Modulation to 180.
Set all Valve Spans to zero except for Valve Channel 1. Set
Channel 1 to 100 %.
4. The first part of this procedure finds a minimum
acceleration Reference Level that is sufficiently low as not to damage
any product, for the mounted product case, but high enough that each
vibrator operates smoothly.
For the empty table case, monitor the average of the feedback
accelerometers and increase the Valve Output Setting until the
acceleration reads approximately 3 gRMS. For the mounted
product
case, monitor the response accelerometer on the product and increase
the Valve Output Setting until the acceleration reads the minimum level
required which allows each vibrator to operate smoothly. If,
during the following steps, the selected acceleration Reference Level
has to be increased so that one or more vibrators operates smoothly,
repeat steps 5 and 6 from the beginning at the new level.
Record
the Valve Output Setting (a number between 0 and 200).
5. Turn on vibration by applying this Valve Output
Setting
in the manual mode. Record the acceleration achieved by the
current output channel.
6. Return the Valve Output Setting to 0, set the
current
Valve Channel Span to 0%, and set the next Valve Channel Span to 100 %.
7. Repeat steps 5 and 6 until acceleration values
are recorded for all Valve Channels.
8. The channel with the lowest acceleration reading
is the
“weakest” channel and its Valve Channel Span will
then be
set to 100%. The second part of the procedure determines the
Valve Channel Span settings for each of the other output channels so
that each channel contributes an equal amount of energy to the
vibration table, or the product mounted in the fixture, as read by the
accelerometers.
9. Turn on vibration by applying the final Valve
Output
Setting in the manual mode. One at a time, select each Valve
Channel Span, except for the weakest channel, and adjust its value (a
number between 0 and 100 %) until the acceleration reading is equal to
the final selected Reference Acceleration Level. Record the
Valve
Channel Number and the Valve Channel Span setting.
10. Return the current Valve Channel Span to 0 and select the next
one. Note that the Span setting for the weakest Valve Channel
Number should be recorded as 100 %.
11. Repeat steps 9 and 10 until Span values are recorded for all Valve
Channels.
12. Enter all the Span values into the controller. Operate
the
vibration table at a level between 5 and 10 gRMS feedback (or
Response), or the level to be applied during a screen, and verify
smooth continuous sounding vibrator noise.
This completes the balancing procedure.
For technical assistance contact Screening Services and Training via
e-mail. scrserv@cox.net
