A small movie show you the casting start with DC and EMC molds. GLS U40 – Casting start with DC and EMC molds
The GLS sensor can be placed very easily on his support. No regulation or adjustment. A change of GLS is made in only 1 minute !
Calibration made each 8-12 month only! A short test with an aluminium plate at a specific distance can be made. If the value given from the GLS is always the same for this distance, you don’t need to make a calibration.
The GLS sensor is robustly developed, that mean this sensor is very appropriate for an environment of a casthouse.
The inductive head is not sensitive to other neighboring objects and fume contrary to a capacitive head and laser sensors type.
In case of short wave of metal, the sensor is not sensible because the head makes an average measure of the whole surface of the inductive head.
For casting machines with automatic metal level regulation, the number one reason for flow stoppage is loss of control of the metal level during filling of the moulds. The inductive sensors that are generally used have a measuring range of 40 to 50 mm. The mould is therefore filled without measuring the level of metal, with the plugs in fixed positions. If, for some reason, the filling time of the different moulds varies too much, the cast will be interrupted for safety reasons. This occurs when the interval of time between the first and last moulds reaching their desired levels is too great.
The solution for resolving the mould filling issue is to measure the level as soon as the metal arrives in the bottom block. This requires use of a sensor with a larger measuring range.
The “GLS” is designed to measure the metal level in the moulds. The system consists of a Micro-Epsilon U40 standard measuring head fixed on an electrical lifting jack. This lifting jack is equipped with an incremental encoder for measuring its movements and two limit switches that determine the measurement reference (top) and the maximum travel (bottom).
The central command board collects the signals coming from the Micro-Epsilon measurement system, the encoder and the top limit switch. It calculates the value of the level to be transmitted to the machine for casting and controls the movements of the head as necessary. It also has certain maintenance options for making the calibration easier.
The device has a Micro-Epsilon head with a measuring range of 40 mm (Level Value, GLS-U40). It is fixed onto a lifting jack with a travel of 160 mm (Head position, encoder); the total measuring range is therefore the sum of the two values, or 200 mm.
The GLS output signal (respectively 4-20 mA) is calculated based on the 200 mm distance, no matter what type of sensor is being used (U15 or U40).
This means that the U15 sensor can never provide 20 mA at the end of the spectrum, given that its measuring head is limited to 20 mm. As in the case of the earlier recorders, the electrical output signal (4 mA) is inverted: for safety reasons, the zero corresponds to the maximum level (200 mm).
The signal provided therefore corresponds to the sum of the value measured by the head and the distance between the head and its maximum top position (as given by the encoder and the upper limit switch).
As long as the value measured by the head (μEpsilon) is within the margins of 10 mm-30 mm (U40: +/- 8 mm, U15: +/- 4 mm), no movement is made. This is to prevent an excessively large number of movements, especially during the continuous phase where the variations in the level are extremely minor. Of course, even if the lifting jack is not moving, the measure will always show the actual value of the distance from the metal. As soon as the level of aluminium goes outside this range, the GLS head will automatically monitor metal level variations in the moulds. In order to preserve the machinery, the lifting jack will reposition the head as soon as the measurement is stable if the metal advances by 1 mm (U40 or 0.5 mm U15) after 20 seconds.
The range where the lifting jack does not move is always taken into consideration when calculating the exact value of the movement to be made. The output signal is continuously calculated with the sum of the signal measured and the distance given by the encoder, and its value is always exact, irrespective of the direction of movement.