Selection of ultrasonic sensors, instruments and systems for industrial applications

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OP - US 1
Airborne sound based distance meter.

Precision distance measurements, contact-free, in industrial environment. Thickness measurements using reference points. Operation principle: The distance is measured by the time-of-flight of airborne ultrasound pulses (frequency 100 kHz). Transmitter and receiver is the external sensor OP-US 1. The thickness is determined by the difference between the reference value (distance to the object´s support) and the measured value (distance to the object surface). The repetition rate is 50 Hz.

Highlights:

- contact-free from front face
- high precision (1/10 mm or better)
- suitable for process control
- filters, noise suppression
- easy set up and easy control, PC based

more information:- sensor -interface -algorithms -software -accessories

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Sensor OP-US S1

- used for thickness and distance measurements

- internal reference reflector

- measuring range starts from front face
 
 
 
 
 
 
 
 

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Accessories

Sometimes measuring tasks can only be solved using specific additional means. Mostly these are software changes, but sometimes mechanical accessories are needed. In the following some accessories are listet and described. The following describes some accessories:
The focussing paraboloid OP-US FS can be mounted directly on the sensor. The measuring spot has a diameter of approximatly 2 mm, but its range is limited by only a few mm. The applications for focused sensors are the measurement of small objects such as wires, ropes or strongly curved or declined surfaces.
With the deviation mirror the ultrasound beam can be deflected to the opposite direction. (for transmission and reception). Due to this, the sensor can be turned down, while measuring in the upward direction. With this device the sensor is protected from larger particles, which could fall down and damage the sensor. . The deviation mirror is directly mounted on the sensor.
Precision measurements need a controlled medium between the sensor and the object to be measured. The best way to manage this is to superimpose a strong and constant airflow at right angles to the measuring ultrasound beam. Small variations and striae in the air are thus suppressed. This is important if hot surfaces are present.

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Interface

Interface Display: Number of digits .......................................5

Analog out: Current interface ..........................4..20 mA (resolution 12 bit)

Optional: voltage interface ............... 0 ..5 V

Switch contact: Relay .............................................. max. 1A

Digital interface: Seriel RS-232 ............................ 9 pin Sub D (4800 baud)

Control inputs: programmable push button and up/down switch.

optional:external synchronisation (1 LS/TTL).
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Evaluation algorithms in data processing:

- adjustable gates to exclude reflectors

- automatic tolerance bands for noise suppression

- filtering, averaging

- automatic gain control

Algorithms for stabilization:

- internal temperature compensation

- object slope compensation (pat.pend.)

- automatic reference measurements are taken, if the object has left the measuring area.

- Timing control to exclude entrance and exit effects in periodic measurements.

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Software

The measured results are available at the RS232 interface and can be processed by different sofware programs. A special windows program is availabel, which can be controled in seperate windows and which transfers the values on-line in the first column of an EXEL worksheet.


 

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OP - US 2

Application Field: Precision thickness measurements, contact-free, in industrial environment. Process control and quality control.

Operation principle: The thickness is measured by the time-of-flight of airborne ultrasound pulses (frequency 100 kHz) to both sides of the test object. Transmitter and receiver is the external sensor OP-US 1. The thickness is determined by the difference between the fixed distance of the two sensors and the sum of the two distance measurements.

Highlights:

- contact-free from front face
- high precision (1/10 mm or better)
- suitable for process control
- filters, noise suppression
- easy set up and easy control, PC based

more information:- sensor -interface -algorithms -software -accessories -back
 

Standard shapes

The achievable accuracy of thickness measurements with airborn ultrasound depends on the length of the free air gap between the sensors and the object to be measured. A larger gap gives more space for the measured object and more place for the operator, but decreases the accuracy. Three standard shapes are available, each of them left- or right handed (type L or R, type L in the picture). A larger width can be customized with aluminium profiles. Deviation mirrors and fans can be mounted.

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OP-US 2 for continuous production processes:
OPUS2 mit Nullung

Especially designed for continously produced products, where no reference measurements can be done, an automatic zero measuring scanner is available. Periodically the thickness meter is removed from the product line and a reference measurement is made. The software updates the internal value automatically for the distance of the sensors. The achievable accuracy (depending of course on the individual problems) is about +/- 0,01 mm. By averaging higher accuracies up to 0.001mm are feasable. The exact shape should be matched to the measuring task. For measuring ranges up to 3 mm, the distance of the sensors should be about 20 mm, to give a high accuracy. The standard range for scanning, that is the maximum distance of the measuring point from the border of the product, is 320 mm. The instrument is oprated with 110/220 V A.c. It should be mounted on a stable and independent rack.

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OP - US S2 / S3

Sensor OP-US S2 The sensors OP-US S2 and the microfone OP-US S3 differ in the electronic design, in the evaluation algorithms and in the application.

Housing: aluminum cylinder 60 mm diameter, 48 mm length.
Fastening and electrical connection via a threaded bolt M24 x 1.5 and mains lead cleat. Total length 84 mm. Two holes in the cover: operation of the potentiometer and two color LED.

Electrical connection: 12..30V, DC, 50 mA. 3-wire cable. After power-on the LED displays red during the setup time.

 

Distance sensor OP-US S2

Application:The sensor is an ultrasonic distance meter which can be used to control a niveau within two limits or related application. By selection of a small hysteresis the sensor can be used to switch at a threshold distance.

Operation: The only parameter which can be controled locally by screw driver adjustment is the switching distance. Internal parameters as averaging, noise supression, limits, gates, hystereses are factory programed.
The LED is green, if the switch is on and the sensor detects an echo in the acceptance range. If the distance is larger than the adjusted threshold, the switch turns off and the LED turns red. This remains up to the case, that the distance becomes smaller than the acceptance range.

Options: analog out, laser pointer, external trigger input.

 

Airborn sound microfone OP-US S3


Application: The sensor OP-US S3 is used to monitor the integrity of high pressure systems or related applications by evaluation of the frequency content of the environmental noise. The sensor scans the frequency content of the airborne sound and activates the alarm output if repeatly ultrasonic waves are detected. A leakage in a high pressure system is an excelent source for airborne sound.

Operation: The only parameter which can be controled locally by screw driver adjustment is the noise level. Internal parameters as averaging, noise supression, limits, gates, hystereses are factory programed.
The LED is green, if the switch is on and the sensor detects an echo in the acceptance range. If the sound amplitude is larger than the adjusted threshold, the switch turns off and the LED turns red. This remains up to the case, that the noise level becomes smaller than the acceptance range.

Option : Front side LEDs.
Accessories: Test transmitter with variable output to check the sensor performance.

 

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US - Tester

Application:

The US-TESTER is made for tribological investigations and characterization of surface and surface layer under the influence of ultrasonic vibrations.

The test setup constists of a controllable oscillator (amplitude, frequency and duration) and an adapted amplifier. The parameters are controlled by the internal computer or by an external PC.
This instruments operates the ultrasonic probe, which can be attached to the test specimen with various interfaces and various loads.

The impact on the surface ist evaluated by a microscope.

 

Options: different resonance frequencies of the probe or different vibration directions of the tip.
 

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Systems


Examples of systems in poduction and quality control.

 

Quality control in wood production. The task is to measure the thickness and the curvature of the plates along two tracks on the wood plate passing the measuring frame.

 

system-1
 
 
 
 

3-dimensional scanner

Scanner for plastic foils. The thickness distribution over the area of the plastic sheet is automatically measured and displayed. The forward feed of the foil is syncronized with the transverse scan. The handling is similar to a copy machine.


  system-2
 

4-dimensional scanner

Shape determination of rotationally symmetrical steel objects. Determination of diameters, ovalities. height of connection lines. The object is scanned with a focused sensor.

Axes: - turntable - x-axes of the scanner - y-axes - angle of sensor versus the surface

system-3

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