Method and apparatus for monitoring and controlling resistance spot welding
US4694135A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 9, 1986 |
| Grant date | Sep 15, 1987 |
| Priority date | — |
| Expiry date | Jul 9, 2006 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB23K11/256
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.