| 摘要 |
Apparatus and accompanying methods for use therein for measuring and controlling weld indentation during resistance welding operations. During a welding operation, the apparatus measures changes in a distance separating a reference point located on an electrode assembly (141, 142) and a region situated on the surface (113, 114) of the workpiece (105, 106) being welded wherein the region is not substantially indented by the electrode. Specifically, a distance measuring system (200, 400) first establishes the location of the surface relative to the electrode (103, 104) before any welding current is passed through the weld area. The indentation is repeatedly measured by detection of ultrasonic echoes (120, 123) from the surface of the material being welded. Such measurements are taken at frequent intervals during the current flow period during which the weld (117) is formed in order to determine on a continuous basis the indentation of the electrode into the surface. The welding power (150) may be terminated when the measured indentation reaches the desired value. In order to obtain more precise control of the indentation, the rate at which indentation occurs can be measured and the welding power can be changed on a half cycle by half cycle basis (612, 613) to increase or decrease the indentation rate according to a desired indentation program (608). |
