Method for detecting and identifying defects in a laser beam weld seam
AssigneeAerospatiale Matra CCR
InventorBruno Esmiller
Life of this patent
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Abstract
A method for detection and identification of defects in a weld seam created using a laser beam. According to this method, at least two measurement signals are acquired in real time delivered by optical sensors (C1 to C6) detecting variations in luminous intensity of the plasma formed by the laser beam (14). These signals are then combined by applying a mathematical operation. The combined signal obtained is then compared to a predetermined threshold. Depending on the result of this comparison, a determination is made of the presence or absence of a defect corresponding to the operator used.
Claims55
A method for detecting and identification of defects at the time of realizing a welding seam (6) by means of a laser beam (14) forming a plasma in a welding region, according to which at least two measurement signals are acquired in real time, said signals being supplied by distinct optical sensors (C1 to C6) that detect the variations in luminous intensity of the plasma, characterized in that the measurement signals are combined by applying to them at least one mathematical operator suitable for detecting a corresponding defect, in order to obtain at least one combined signal;
- each combined signal is compared to a predefined threshold and the presence or absence of a defect is diagnosed that corresponds to each mathematical operator according to the result of the comparison.
A method for detecting and identification of defects at the time of realizing a welding seam (6) by means of a laser beam (14) forming a plasma in a welding region, according to which at least two measurement signals are acquired in real time, said signals being supplied by distinct optical sensors (C1 to C6) that detect the variations in luminous intensity of the plasma, characterized in that the measurement signals are combined by applying to them at least one mathematical operator suitable for detecting a corresponding defect, in order to obtain at least one combined signal;
- each combined signal is compared to a predefined threshold and the presence or absence of a defect is diagnosed that corresponds to each mathematical operator according to the result of the comparison;
- wherein the mathematical operator is chosen from the group comprising addition, subtraction, multiplication, division and a combination thereof;
- wherein the method is applied to welding of a stiffener (12) onto a metal plate (1) using two laser beams (14) arranged on either side of the stiffener, wherein two groups of at least one optical sensor (C1, C2, C3, C4, C5, C6) are used and disposed on either side of the stiffener;
- said optical sensors of the two groups being identical, the measurement signals supplied by one sensor of each group are added and the presence of an insufficient interpenetration of the welding seams owing to insufficient laser beam power is detected when the result is lower than a predefined first threshold.
A method for detecting and identification of defects at the time of realizing a welding seam (6) by means of a laser beam (14) forming a plasma in a welding region, according to which at least two measurement signals are acquired in real time, said signals being supplied by distinct optical sensors (C1 to C6) that detect the variations in luminous intensity of the plasma, characterized in that the measurement signals are combined by applying to them at least one mathematical operator suitable for detecting a corresponding defect, in order to obtain at least one combined signal;
- each combined signal is compared to a predefined threshold and the presence or absence of a defect is diagnosed that corresponds to each mathematical operator according to the result of the comparison;
- wherein the mathematical operator is chosen from the group comprising addition, subtraction, multiplication, division and a combination thereof;
- wherein the method is applied to welding of a stiffener (12) onto a metal plate (10) using two laser beams arranged on either side of the stiffener, wherein two groups of at least two optical sensors (C1, C2, C3;
- C4, C5, C6) are used and detecting variations in luminous intensity of the plasma in different optical bands;
- said optical sensors of the two groups being identical, the measurement signals supplied on the one hand by a first pair of identical sensors are added and on the other hand the measurement signals supplied by a second pair of identical sensors are added;
- the one sum is multiplied by the other sums so obtained and an inadequate interpenetration of the welding seams is detected, which due to a defect other than insufficient laser beam power, when the result is greater than a predefined second threshold.
A method for detecting and identification of defects at the time of realizing a welding seam (6) by means of a laser beam (14) forming a plasma in a welding region, according to which at least two measurement signals are acquired in real time, said signals being supplied by distinct optical sensors (C1 to C6) that detect the variations in luminous intensity of the plasma, characterized in that the measurement signals are combined by applying to them at least one mathematical operator suitable for detecting a corresponding defect, in order to obtain at least one combined signal;
- each combined signal is compared to a predefined threshold and the presence or absence of a defect is diagnosed that corresponds to each mathematical operator according to the result of the comparison;
- wherein the method is applied to edge-to-edge welding of two metal plates using a single laser beam, wherein at least two optical sensors are used that detect variations in the luminous intensity of the plasma in different optical bands, the one measurement signal is divided by the other measurement signal of the measurement signals supplied by two of the sensors and an insufficient thickness of the welding seam is detected, when the result obtained is less than a first threshold and an absence of welding, when the result is greater than a second threshold, greater than the first.
Dependencies are inferred from the claim text.