Process for checking a laser weld seam
First Claim
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1. A process for checking a laser weld seam, comprising:
- selecting materials to be welded and the process parameters of the laser welding process for forming a weld seam,determining the time after welding at which at least a thin skin has solidified on the weld seam and setting this as the earliest measurement start time for a characteristic interval,selecting an optical or thermal signal to be emitted onto and reflected from the weld seam during said characteristic interval,determining the minimal length of a time interval necessary in order to receive detectable signal data, and setting this as the minimal duration of the characteristic time interval,laser welding said materials to form a weld seam by a computer controlled process comprising;
emitting said optical or thermal signal onto said seam in said area in which at least a thin skin has solidified and detecting reflected signal data,comparing the detected reflected signal data with desired values,providing a violation signal each time the detected reflected signal data does not correspond with the desired values, andevaluating the laser weld seam on the basis of said violation signals,wherein only signals detected within the characteristic time interval are taken into consideration.
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Abstract
When laser beam welding one or more work pieces faults may occur, which lead to unacceptable losses in quality. A check process is provided, which reliably recognizes seam faults in a seam which is introduced into one or more workpieces by means of laser beam welding. Characteristic signals are detected from the region of the seam using a sensor and compared with an index value or set value, and only signals are taken into consideration which are detected in a characteristic time interval following the laser beam welding, which begins, at the earliest, following the solidification of the seam.
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Citations
17 Claims
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1. A process for checking a laser weld seam, comprising:
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selecting materials to be welded and the process parameters of the laser welding process for forming a weld seam, determining the time after welding at which at least a thin skin has solidified on the weld seam and setting this as the earliest measurement start time for a characteristic interval, selecting an optical or thermal signal to be emitted onto and reflected from the weld seam during said characteristic interval, determining the minimal length of a time interval necessary in order to receive detectable signal data, and setting this as the minimal duration of the characteristic time interval, laser welding said materials to form a weld seam by a computer controlled process comprising; emitting said optical or thermal signal onto said seam in said area in which at least a thin skin has solidified and detecting reflected signal data, comparing the detected reflected signal data with desired values, providing a violation signal each time the detected reflected signal data does not correspond with the desired values, and evaluating the laser weld seam on the basis of said violation signals, wherein only signals detected within the characteristic time interval are taken into consideration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A process for checking a laser weld seam, comprising:
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selecting materials to be welded and the process parameters of the laser welding process for forming a weld seam, determining the time after welding at which said weld seam has solidified and setting this as the earliest measurement start time for a characteristic interval, selecting a speed or power at which said laser when redirected onto said solidified weld seam does not cause said weld seam to remelt, determining the minimal length of a time interval necessary in order to receive a detectable signal data from the reflection of said redirected laser beam, and setting the two-fold of this as the minimal duration of the characteristic time interval, laser welding said materials to form a weld seam by a computer controlled process comprising; redirecting said laser beam onto said seam in said area in which said weld seam has solidified and detecting reflected signal data, comparing the detected reflected signal data with desired values, providing a violation signal each time the detected reflected signal data does not correspond with the desired values, and evaluating the laser weld seam on the basis of said violation signals, wherein only signals detected within the characteristic time interval are taken into consideration.
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14. A computer controlled process for checking a laser weld seam, wherein said computer directs process steps comprising:
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guiding a laser to form a first step-weld with a laser beam, guiding the laser to form a second step weld with said laser beam, steering said laser beam back to said first step weld after said first step weld has solidified, wherein the laser beam is guided onto the first step weld with insufficient energy input to melt said first step-weld, and detecting the reflected signal data, comparing the detected reflected signal data with desired values, generating and recording in memory a violation signal each time the detected reflected signal data does not correspond with the desired values, and evaluating the quality of the laser weld seam on the basis of said violation signals.
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15. A process for checking a laser weld seam, comprising:
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selecting materials to be welded and the process parameters of the laser welding process for forming a weld seam, determining the time after welding at which at least a thin skin has solidified on the weld seam and setting this as the earliest measurement start time for a characteristic interval, determining the minimal length of a time interval necessary in order to receive detectable signal data, and setting this as the minimal duration of the characteristic time interval, laser welding said materials to form a weld seam by a computer controlled process comprising; receiving signals of optical and/or thermal type which are emitted out of the area of the seam in which at least a thin skin has solidified however the seam is still glowing, comparing the detected signal data with desired values, providing a violation signal each time the detected reflected signal data does not correspond with the desired values, and evaluating the laser weld seam on the basis of said violation signals, wherein only signals detected within the characteristic time interval are taken into consideration. - View Dependent Claims (16, 17)
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Specification