Temp Comp Products
In-Process Temp Comp
Ultrasonic Arrays developed the first non-contact ultrasonic thickness gage in 1984. This gage, the TMS-1000 was developed to overcome the inherent problems in attempting to use contact and laser measuring devices in process applications.
This gage was revolutionary in that it was self calibrating for any factors that would affect measurement accuracy, even for fixture movement. An external reference bar target was used as a standard to eliminate variables that affected the speed of sound (such as temperature). More recently this technology has been improved by adding a second reference bar to each sensor.
Patented Reference-Bar Technology
Our commitment is to provide measurement systems that meet specification in the intended environment, day in and day out. A key component of this requirement is the UA patented double reference bar technology, used by the more recently developed TMS 5000 and DMS 5000. Components of any system can change over time, affecting accuracy and performance. The double reference bar provides a "gold standard", to remove any changes that occur in the UA gaging system. Shown to the right in Figure 1 and Figure 2, are different views of a UA double reference bar transducer.
Two external reference targets are precisely mounted at known distances, from the sound transmitting/receiving surface. Exact measurements of distance is measured to these fixed locations during the same period as thickness/distance measurements are taken to the target surface. If any factor (temperature, humidity, air pressure, electronic component drift, etc.) causes the sound waves to measure the target incorrectly, the reference bar compensation will correct the error. There is no lag or time delay and there is no aging or drift of the system. A warm up period is not required.
High frequency ultrasound is transmitted from the sound producing surface to the reference bar and back, 125 times per second. If the distance to the reference bar changes, this means that the speed of sound has changed. The microprocessor in the gage automatically corrects the measurement.
Most of the sound passes the transducer reference bar(s), and travels to the product surface and returns to the transducer receiver.
The thickness measurement is equal to the separation of the transducers S less the distance measured to the top surface d1 and to the bottom surface d2. The separation S is constantly measured and compared to what S was when the transducers were originally calibrated, correcting for any fixture movement.
Temperature, Vibration and Collision Compensation with Air-Flow Control
In a process line, the temperature swings caused by the process and ambient temperature variation between the hot part of the day and the cold part of the night can easily be 50 degrees F. This means that the structures of the line, including the fixtures supporting the sensors are moving. Fixtures can also move for other reasons, including collisions with product, personnel standing on the fixtures for maintenance, being bumped with a fork lift, internal stress relief in the fixtures, etc. UAI's patented AutoZcal feature, automatically corrects for movement, no matter what the cause.