Displacement monitoring system for stud welding
AssigneeEaton Corporation
InventorsMichael L. Killian, Michael D. Orr
Life of this patent
Estimating the term…
Abstract
A system (10) and method for predicting weld quality in a stud welding system by measuring the displacement of a movable shaft (20) with respect to the gun body (12) during the weld process. A sensor (34) is positioned with respect to the welding system in order to produce a series of discrete signal values each indicative of this displacement. These values are plotted graphically and used to produce a weld "signature" which can be compared with signatures of welds of known quality to more accurately predict the quality of the current weld. Based on these weld signatures, various weld parameters including current, time and lift can then be adjusted until a consistent signature indicative of good weld quality is produced.
Claims12
In an arc stud welding system including a stud welding gun having a body and a movable gun shaft mounted to said body so as to provide reciprocal movement of said shaft with respect to said body, said shaft having a distal end having means for carrying a stud, wherein said welding cycle includes positioning said stud against a workpiece in a fully extended position of said shaft, compressing said shaft with respect to said gun into a compressed position of said shaft, lifting said stud off of said workpiece into a retracted position of said shaft and plunging said stud toward said workpiece to a plunged position of said shaft, a method of monitoring said stud welding process and predicting resulting weld quality, said method comprising the steps of:
- positioning a sensor with respect to said welding system, said sensor being adapted to measure instantaneous discrete distances representative of relative displacement between said gun body and movable shaft;
- electrically connecting a signal processing unit to said sensor, said signal processing unit adapted to associate each said discrete distance measurement with a unit of time;
- associating certain of said discrete signal values with said compressed and plunged positions of said shaft;
- determining an effective plunge displacement by subtracting a value associated with said compressed position of said shaft from a value associated with said plunged position;
- and
- predicting good weld quality when said effective plunge displacement falls within a predetermined range of effective plunge values.
An arc stud welding system comprising:
- a stud welding gun having a body and a movable gun shaft mounted to said body so as to provide reciprocal movement of said shaft with respect to said body between a compressed position and a plunged position, said shaft having a distal end having means for carrying a stud;
- a sensor positioned with respect to said welding gun so as to measure discrete distances representative of the instantaneous relative displacement between said gun body and movable shaft, wherein said welding gun has a pair of target points, one said target point lying on an exterior surface of said gun body and a second target point on an exterior surface of said movable gun shaft, said sensor including means for measuring the relative displacement between said target points;
- and
- a signal processing unit electrically connected to said sensor and including processor means for associating certain of said discrete distance measurements with a unit of time as well as with said compressed and plunged positions of said shaft, said processing unit further including means for predicting resultant weld quality by subtracting a value associated with said compressed position of said shaft from a value associated with said plunged position of said shaft.
Dependencies are inferred from the claim text.