Weld energy reduction by using concurrent non-destructive evaluation

Johnson, John A.; Carlson, Nancy M.

doi:10.1016/0308-9126(86)90108-2

Cited by 6 publications

(5 citation statements)

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“…The proof-of-principle for a weld inspection system was achieved with the concurrent inspection system that uses pattern recognition to detect flaws in the solidified weld bead in partially completed welds [4,5]. In the concurrent welding research, a transducer, mounted inside a liquid-filled tire, was positioned on the welding side of a sample to sense defects 330 mm behind the welding torch in the solidified weld metal.…”

Section: Previous Workmentioning

confidence: 99%

Ultrasonic Detection of Weld Bead Geometry

Carlson

Johnson

1987

Review of Progress in Quantitative Nondestructive Evaluation

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Section: Previous Workmentioning

confidence: 99%

Ultrasonic Detection of Weld Bead Geometry

Carlson

Johnson

1987

Review of Progress in Quantitative Nondestructive Evaluation

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“…The purpose of the ultrasonic sensor is to detect defects in the solidified weld metal on a pass-by-pass basis [2][3][4][5] for a multipass, pulsed gas metal arc welding (GMA W) process. The sensor is being developed under the Programmable Automated Welding System (PAWS) project.…”

Section: Introductionmentioning

confidence: 99%

“…The absence of a signal above the threshold level in the computer-calculated time interval indicates a disruption of the sound path by a defect. The ultrasonic sensor system then provides an input signal to the weld controller about the defect condition.The purpose of the ultrasonic sensor is to detect defects in the solidified weld metal on a pass-by-pass basis [2][3][4][5] for a multipass, pulsed gas metal arc welding (GMA W) process. The sensor is being developed under the Programmable Automated Welding System (PAWS) project.…”

mentioning

confidence: 99%

Noncontacting Ultrasonic System for Concurrent Defect Detection in Solidified Weld Metal

Carlson

Johnson

Larsen

1993

Review of Progress in Quantitative Nondestructive Evaluation

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INTRODUCTIONIn-process ultrasonic sensing of welding allows detection of weld defects in real time. A noncontacting ultrasonic system is being developed to operate in a production environment. The principal components are a pulsed laser for ultrasound generation, an electromagnetic acoustic transducer (EMAT) for ultrasound reception, and a PC-based data acquisition system which determine the quality of the weld on a pass-by-pass basis. The laser/EMAT system interrogates the area in the weld volume where defects are most likely to occur [5]. This area of interest is identified by computer calculations on a pass-by-pass basis using weld planning information provided by the off-line programmer. The absence of a signal above the threshold level in the computer-calculated time interval indicates a disruption of the sound path by a defect. The ultrasonic sensor system then provides an input signal to the weld controller about the defect condition.The purpose of the ultrasonic sensor is to detect defects in the solidified weld metal on a pass-by-pass basis [2][3][4][5] for a multipass, pulsed gas metal arc welding (GMA W) process. The sensor is being developed under the Programmable Automated Welding System (PAWS) project. The purpose of the PAWS program is to demonstrate the integration of the latest welding technology into a single system. The PAWS system consists of a central control computer, an off-line programmer for planning, and eight different sensors. This paper discusses one of those sensors. The sensor system will be demonstrated on thick section (31.8 to 41.3 mm, 1.25 to 1.625 in.) steel weld samples.The ultrasound is generated by a short duration (11 ns) light pulse from an Nd:YAG laser with an exit beam power of 56 mJ/pulse. The 1 mm laser spot is delivered at a 20 Hz rate to the solidified top surface of the weld several inches behind the electrode using focusing optics mounted on the laser head [6,7]. The ultrasonic detector is an EMA T and amplifier designed and fabricated for PAWS at the National Institute of Standards and Technology in Boulder, Colorado [8]. The permanent magnet EMAT generates a magnetic field in the weld sample. The motion of electrons due to the sound generated by the laser pulse interacts with the magnetic field, changing an associated electrical field. This interaction is detected by a pickup coil. The signal is then evaluated as an ultrasonic A scan. The ultrasonic system includes the hardware and software necessary to monitor the condition of the solidified weld metal while receiving and sending information to a weld controller about the quality of the solidified weld bead. A first step in devising a noncontacting technique for sensing defect generation in the welding process is to develop a method for generating sound waves in the material. In this system, ultrasound is generated by a focused, 1 mm (0.039 in.) diameter laser spot from a pulsed Nd: Y AG laser operating at 1064 nm. The short duration, 11 ns, laser pulse has a peak intensity of 107 W/cm2 and generates high freq...

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“…Ultrasonic sensing of the welding process with contact techniques has been successfully used for detecting the geometry of the molten/solid interface [2,3] and the presence of defects in solidified weld metal [7]. The molten/solid interface geometry can be detected with refracted shear waves using a contact piezoelectric transducer mounted on a lucite wedge positioned opposite the welding electrode.…”

Section: Introductionmentioning

confidence: 99%