An LED driver for controlling the intensity of an LED light source includes a power converter circuit for generating a DC bus voltage, an LED drive circuit for receiving the bus voltage and controlling a load current through, and thus the intensity of, the LED light source, and a controller operatively coupled to the power converter circuit and the LED drive circuit. The LED drive circuit comprises a controllable-impedance circuit coupled in series with the LED light source. The controller adjusts the magnitude of the bus voltage to a target bus voltage and generates a drive signal for controlling the controllable-impedance circuit. To adjust the intensity of the LED light source, the controller controls the magnitudes of both the load current and the regulator voltage. The controller controls the magnitude of the regulator voltage by simultaneously maintaining the magnitude of the drive signal constant and adjusting the target bus voltage.

Load Control Device for a Light-Emitting Diode Light Source

The present invention provides a weld monitoring system and method that monitors and automatically coordinates information on the quality of each weld in a workpiece having one or more welds. In particular, each weld in the workpiece is automatically analyzed at the time it is being made using weld sensors such as those that measure current, wire feed, voltage, and gas flow to produce information on the quality of the weld. Using this information, the welds are sorted, displayed, and logged with workpiece and weld number information which is provided to the operator in real-time and stored in a computer for access at a later time for quality control or other purposes. Therefore, the system and method enables welds of a quality less than a pre-determined quality for the weld to be identified in real-time and information concerning any particular weld to be accessed at a later time.

Method and system for weld monitoring and tracking

A real-time virtual reality welding system including a programmable processor- based subsystem, a spatial tracker operatively connected to the programmable processor- based subsystem, at least one mock welding tool capable of being spatially tracked by the spatial tracker, and at least one display device operatively connected to the programmable processor-based subsystem. The system is capable of simulating, in virtual reality space, a weld puddle having real-time molten metal fluidity and heat dissipation characteristics. The system is further capable of displaying the simulated weld puddle on the display device in real-time.

System and method providing arc welding training in a real-time simulated virtual reality environment using real-time weld puddle feedback

A system and a method for tracking and analyzing welding activity. Dynamic spatial properties of a welding tool are sensed during a welding process producing a weld. The sensed dynamic spatial properties are tracked over time and the tracked dynamic spatial properties are captured as tracked data during the welding process. The tracked data is analyzed to determine performance characteristics of a welder performing the welding process and quality characteristics of a weld produced by the welding process. The performance characteristics and the quality characteristics may be subsequently reviewed.

System for tracking and analyzing welding activity

A system for training welders that includes a data generating component, a data capturing component and a data processing and visualization component. The data generating component operates in real time and derives data from an actual manually-executed weld and further includes a weld process-specific jig, a calibration block positioned on the jig, wherein the geometric configuration of the calibration block is specific to a particular type of weld joint, a weld coupon positioned on the welding process-specific jig adjacent to the calibration block, a welding gun for use by a trainee, wherein the welding gun is operative to form the weld; and at least one target mounted on the welding gun that is recognized by the data processing and visualization component for providing multidimensional position and orientation feedback to the trainee.

Welding training system

A method and apparatus are disclosed for analyzing the dynamic resistance of a resistance spot welding process to determine the time of an expulsion event and use that time as the weld completion time for controlling weld termination via a weld feedback signal, controlling automatic current stepping, and identifying maintenance needs. A preconditioning pulse is used to stabilize the weld process and aid in obtaining interpretable resistance information. After an initial blanking period the resistance curve is analyzed by calculating first and second derivative values and applying several algorithms that make possible the computer recognition of characteristic resistance curve shapes resulting from weld expulsion under good geometry, bad geometry and edge weld conditions.

Method and apparatus for monitoring and controlling resistance spot welding

During a weld period in the formation of a resistance spot weld the weld parameters are monitored. and data representIng the weld resistance curve and the power curve are acquired and stored for analysis by a suitably programmed computer. A prediction of the quality of a weld, and specifically as to whether a weld is a nugget or a sticker is made by calculating the ratio of weld energy after the onset of melting to the total weld energy, and also the ratio of the resistance drop afterthe resistance peak to the peak resistance, and then utilising the weighted sum of the energy ratio and the resistance drop ratio, as a weld quality indicator.

Method of predicting the quality of a resistance spot weld

During a weld period the weld parameters are monitored and data representing the weld resistance curve and the power curve are acquired and stored for analysis by a suitably programmed computer. The derivative of R, R is calculated and stored and the function is divided by power P to obtain R/P. The resistance curve is searched to obtain the maximum value Rm which occurs during the heating phase and the function R/P is searched prior to the time of Rm to find the maximum of that curve representing the highest rate of resistance increase. Then the R/P curve is searched subsequent to its maximum to determine when the function reaches a specified percentage of the maximum. That value occurs at the knee of the resistance curve and approximates the onset of melting in the weld. A prediction of whether a weld is a nugget or a sticker is made by calculating the ratio of weld energy after the onset of melting to the total weld energy, the ratio of the resistance drop after the resistance peak to the peak resistance, and then a weighted sum of the energy ratio and resistance drop ratio. An edge weld geometry is detected by calculating from the resistance and power curves the weld energy during the period of expulsion, if any, divided by the cumulative energy between the onset of melting and the end of expulsion, a measure of expulsion intensity based on the maximum degree of resistance inflection, and then a weighted sum of the energy value and the inflection value.

Method and apparatus for detecting the onset of melting in a resistance spot weld

METHOD AND APPARATUS FOR PREDICTING AND CON-TROLLING THE QUALITY OF A RESISTANCE SPOT WELD Abstract of the Disclosure During a weld period the weld parameters are monitored and data representing the weld resistance curve and the power curve are acquired and stored for analysis by a suitably programmed computer. The derivative of R, R is calculated and stored and the function is divided by power P to obtain R/P. The resistance curve is searched to obtain the maximum value Rm which occurs during the heating phase and the function R/P is searched prior to the time of Rm to find the maximum of that curve representing the highest rate of resistance increase. Then the R/P curve is searched subsequent to its maximum to deter-mine when the function reaches a specified percentage of the maximum That value occurs at the knee of the resistance curve and approximate the onset of melting in the weld. A prediction of whether a weld is a nugget or a sticker is made by calculating the ratio of weld energy after the onset of melting to the total weld energy, the ratio of the resistance drop after the resistance peak to the peak resistance, and then a weighted sum of the energy ratio and resistance drop ratio. An edge weld geometry is detected by calcu-lating from the resistance and power curves the weld energy during the period of expulsion, if any, divided by the cumulative energy between the onset of melting and the end of expulsion, a measure of expul-sion intensity based on the maximum degree of resis-tance inflection, and then a weighted sum of the energy value and the inflection value.

Method and apparatus for predicting and controlling the quality of a resistance spot weld

During a weld period in the formation of a resistance spot weld the weld parameters are monitored, and data representing the weld resistance curve and the power curve are acquired and stored for analysis by a suitably programmed computer. The derivative of R, namely R is calculated and stored, and this derivative is divided by power P to obtain R/P. The resistance curve is searched to obtain the maximum value Rm which occurs during the heating phase, and the function R/P is searched prior to the time of Rm to find the maximum of that curve, representing the highest rate of resistance increase. Then the R/P curve is searched subsequent to its maximum to determine when the function reaches a specified percentage of the maximum. That value occurs at the knee of the resistance curve, and approximates the onset of melting in the weld

Dixon Cleveland

Papers

Method and apparatus for monitoring and controlling resistance spot welding

Method of predicting the quality of a resistance spot weld

Method and apparatus for detecting the onset of melting in a resistance spot weld

Method and apparatus for predicting and controlling the quality of a resistance spot weld

Method of detecting the onset of melting in a resistance spot weld