METHOD AND APPARATUS FOR MEASURING AND CONTROLLING INDENTATION IN RESISTANCE WELDING

Apparatus and accompanying methods for use therein for measuring and controlling weld indentation during resistance welding operations are disclosed. During a welding operation, the apparatus measures changes in a distance separating a reference point located on an electrode assembly and a region situated on the surface of the workpiece being welded wherein the region is not substantially indented by the electrode. Specifically, a distance measuring system first establishes the location of the surface relative to the electrode before any welding current is passed through the weld area; the indentation is repeatedly measured by detection of ultrasonic echoes from the surface of the material being welded; such measurements are taken at frequent intervals during the current flow period during which the weld is being formed in order to determine on a continuous basis the indentation of the electrode into the surface; the welding power may be terminated when the measured indentation reaches ...

VERFAHREN UND VORRICHTUNG ZUM MESSEN UND STEUERN DES EINSCHNITTES WAEHREND DES WIDERSTANDSSCHWEISSENS.

SIGNAL CONTROLLED WAVEFORM RECORDER

A DYNAMIC THERMAL-MECHANICAL MATERIAL TESTING SYSTEM UTILIZING A BALANCED MAGNETIC FIELD

Apparatus (100) for a dynamic thermal-mechanical material testing system that not only self-resistively heats and deforms a specimen (170), both under controlled conditions, but also substantially reduces adverse affects in specimen performance, such as magnetically induced motion and non-uniform specimen heating, that would otherwise result from magnetic fields which impinge upon the specimen and are caused by high heating currents flowing in the apparatus. This reduction is achieved by spatially locating high current carrying conductors (102,102') used in the apparatus such that these conductors collectively generate substantially balanced, i.e. substantially equal, and opposite magnetic fields (431,433) that effectively cancel each other out in a volumetric region in the apparatus which contains the specimen and particularly its work zone.

SIGNAL CONTROLLED WAVEFORM RECORDER

A multi-channel electronic waveform recorder, for storing waveform data and time of occurrence information, i.e. a "timetag", for each stored value of an input waveform, is disclosed. Specifically, each channel of the waveform recorder compares a previously stored value of that signal of a corresponding input signal to a current value, and is able to store the current value whenever the difference between the input signal and the previously stored value is a predetermined amount. Each or any selected sub-set of all the channels, through an appropriate switch setting, can determine points in time when, in response to the difference occurring for that channel, all the channels will simultaneously store the current value of these respective input signals.