1 Straightening process
Straightening a work piece is done by bending it with a straightening hammer while the work piece is held by two bearings.
The pressing power of the straightening hammer is compensated by pulling and tensile forces within the work piece.
More force in the straightening hammer increases the pulling and tensile forces in the work piece as well.
Below the neutral beam of the work piece mainly pulling forces appear. These forces may lead into cracking of the work piece.
At sensitive geometries of a work piece such as drills, changes of diameter and so on
and at micro structural changes
caused by earlier treatment of the work piece, cracks will occur cross to pulling forces.
By the high pressing force of the straightening press induced through the straightening hammer into the work piece, it is loaded with static energy directly before the crack builds up.
Part of this energy is converted into changes of microstructure and deformation of work piece – this is the effect wanted.
A larger part of this energy is absorbed to balance the forces within the straightening hammer, the work piece and the bearings.
When a crack occurs part of this static energy is converted into kinetic energy.
2.Flow of Signal
The material of the work piece is extremely stressed in longitudinal direction right before the crack occurs. The crack then releases the tension force in shortest time into the opposite direction.
From the spot of crack occurrence a shock wave moves through the structure of the work piece into the press which is connected to the work piece by high pressure.
Macroscopically the work piece induces, if loaded with enough tension force, impulses into the jigs ( hammer and bearings ).
Under the straightening hammer and at both edges of the work piece a motion will occur by the very sudden de-stressing of the work piece. Thus an impulse is induced according to mass and speed of the work piece into the press.
This impulse will be followed by an impulse answer by the press leading into an characteristic stimulation of oscillation.
3. Signal reading
The very sudden de-stressing of the work piece that follows the crack event stimulate those parts of the press strongest that are in direct contact to the work piece.
Special sensors for reading wide band can detect the oscillation on the surface of those press elements.
CiS.01 uses sensors with sensitivity in high and subsonic band.
The piezo-ceramic element of the sensor is capsuled in a steel housing. This housing can be coupled to the press element with high pressing force.
4. Signal processing
The sensors for CiS.01 react specifically on high frequency signals.
The signal gets pre-amplified and filtered before it is processed in the main amplifier unit. The electric filtration process depresses low frequency "noise" signals that erase out of mechanical sources of the whole system.
The signal gets integrated and amnplitude and energy are available for evaluation.
5. Signal evaluation
After the digitalisation of the signals amplitude and flow of energy are evaluated.
Due to the sophisticated sensor and pre amplification techniques the distance between signal and noise is very comfortable when monitoring amplitude and energy simultaneously
For every straightening position and for at least 50 different work pieces optimised parameters and adjustments can be filed.
This enables CiS.01 to meet the characteristics of each single type of work piece.
If the limits of amplitude and energy that has been set for a certain work piece is crossed the signal input is evaluated as crack.
More limits can be set for break of work piece as well.
The difference of limits between crack and break may be set very large. Thus even very tiny cracks can be recognized and the signal "break" can be taken without overflow of measuring range.
6. Control of Machine (Press)
CiS.01 allows direct communication by serial interface ( RS232) with the straightening controller of the press..
CiS.01 can be connected to an external control e.g. PLC by 24V I/O.
CiS.01 is equipped with an Ethernet interface. This can be used for evaluation purposes and for control purposes.
Optionally CiS.01 230V control current is possibly.
The press can obtain this signals from CiS.01:
-ready
-error
-busy
-crack
-break
CiS.01 needs this signals :
-Start measuring at position 1-8
-next work piece
-test socket
Using
serial interface or Ethernet you may unlimited number of work piece parameters
and detection results.
7. Reliability of process
.In opposite to other calibration methods CIS.01 sensors are NOT calibrated in low frequency up to 200 Hz!
CiS.01 sensors are calibrated in the whole relevant window for measuring up to 200KHz!
This assures the necessary sensitivity in the measuring system.
With every new work piece there is an automatic 3 level self test.
-
level: The whole amplification and filter line is tested with an electric calibration signal. Any variation in amplification or filtration will indicate error .
-
level: Test of connection of sensors. If sensor is not connected or cable defect error is indicated.
-
level: Test of correct coupling to press. An impulse is given by the piezo actuator at the press and same time the oscillation that is induced by this signal is read by sensor. CiS.01 then compares this with a correct coupling result that is filed. On any variation in this process an error in sensor/actuator coupling is indicated.
Sensor and actuator are separate elements that are only coupled through the same press element they are bolted to.
The shape and bolting method of the exchangeable sensor and actuator are the same.
Operating the straightening process with a special specimen of a defined size the whole system can be calibrated.
Regular service and yearly calibration are essential for true function, availability and repeatability of the measuring system.
8. Quality management interface
CiS.01 offers a huge file for statistics. You have access to this file e.g. by external parallel printer, serial port or HTML browser.
CiS.01 can be connected to your INTRANET using its 10Mbit Ethernet socket and hands over the process data from the built in HTML server.
So you can obtain and analyse the present process situation from any pc workstation.
Furthermore CiS.01 can send e-mails to destination defined .