Method for calibrating a sensor for monitoring a melt pool in an additive manufacturing machine
A method for calibrating a sensor for monitoring a melt pool belonging to a system for monitoring a melt pool of an additive manufacturing machine comprises at least the following steps: measuring and recording the value of the signal transmitted by the monitoring sensor when it is not exposed to a reference radiation, exposing the monitoring sensor to the reference radiation, measuring and recording the value of the signal transmitted by this monitoring sensor when it is exposed to a reference radiation, calculating a correction coefficient for this monitoring sensor from a reference value associated with the reference radiation and the values of the signals, and recording in a correction table the correction coefficient for this monitoring sensor and the value of the signal transmitted by the monitoring sensor when it is not exposed to a reference radiation.
1 . A method for calibrating a monitoring sensor for a melt pool in a melt pool monitoring system of an additive manufacturing machine, the method comprising at least the following steps:
measuring and recording a value of a signal transmitted by the monitoring sensor when the monitoring sensor is not exposed to a reference radiation;
exposing the monitoring sensor to the reference radiation;
measuring and recording a value of the signal transmitted by the monitoring sensor when the monitoring sensor is exposed to the reference radiation;
calculating a correction coefficient for the monitoring sensor from a reference value associated with the reference radiation and the values of the signals transmitted by the monitoring sensor when the monitoring sensor is not subjected to the reference radiation and when the monitoring sensor is subjected to the reference radiation; and
recording in a correction table the correction coefficient for the monitoring sensor and the value of the signal transmitted by the monitoring sensor when the monitoring sensor is not exposed to the reference radiation,
wherein an electronic gain of the monitoring sensor is adjustable, and the electronic gain is adjusted to a predefined value before the steps of measuring and recording the values of the signals transmitted by the monitoring sensor.
2 . The method according to claim 1 , wherein the correction table associated with the monitoring sensor is recorded in the melt pool monitoring system of which the monitoring sensor forms a part.
3 . The method according to claim 1 , wherein the electronic gain of the monitoring sensor is set at a maximum before the steps of measuring and recording the values of the signals transmitted by the monitoring sensor.
4 . The method according to claim 1 , wherein the reference radiation to which the monitoring sensor is exposed originates from a light source calibrated with respect to a light intensity and a wavelength, and the calibrated light source comprises a filament lamp equipped with a device for adjusting a light output power.
5 . The method according to claim 1 , wherein the method is implemented with at least two different monitoring sensors, the method comprising at least the following steps:
measuring and recording the value of the signal transmitted by each monitoring sensor when each monitoring sensor is not exposed to a reference radiation;
exposing each monitoring sensor to the reference radiation;
measuring and recording the value of the signal transmitted by each monitoring sensor when each monitoring sensor is exposed to a reference radiation;
calculating a correction coefficient for each monitoring sensor from a reference value associated with the reference radiation and the values of the signals transmitted by each monitoring sensor when each monitoring sensor is not subjected to the reference radiation and when each monitoring sensor is subjected to the reference radiation; and
recording in the correction table the correction coefficient for each monitoring sensor and the value of the signal transmitted by each monitoring sensor when each monitoring sensor is not exposed to the reference radiation.
6 . The method according to claim 5 , wherein the method is implemented with at least two monitoring sensors belonging to the same additive manufacturing machine.
7 . The method according to claim 1 , wherein the method is implemented with at least two monitoring sensors belonging to separate additive manufacturing machines, the method comprising at least the following steps:
measuring and recording the value of the signal transmitted by each monitoring sensor when each monitoring sensor is not exposed to respective reference radiations;
exposing each monitoring sensor to the respective reference radiations;
measuring and recording the value of the signal transmitted by each monitoring sensor when each monitoring sensor is exposed to the respective reference radiations;
calculating a correction coefficient for each monitoring sensor from a reference value associated with each respective reference radiation and the values of the signals transmitted by each monitoring sensor when each monitoring sensor is not subjected to the respective reference radiations and when each monitoring sensor is subjected to the respective reference radiations; and
recording in the correction table the correction coefficient for each monitoring sensor and the value of the signal transmitted by each monitoring sensor when each monitoring sensor is not exposed to the respective reference radiations.
8 . The method according to claim 1 , wherein the method is applied to one or more sensors for monitoring a melt pool in one or more machines for additive manufacturing by powder bed deposition and selective melting.