Electric heating – Metal heating – By arc
Patent
1988-09-22
1990-04-24
Shaw, Clifford C.
Electric heating
Metal heating
By arc
21912512, B23K 912
Patent
active
049202480
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an automatic welding apparatus, more particularly, to an automatic welding apparatus in which arc sensing is carried out.
BACKGROUND ART
In some automatic welding apparatuses, arc sensing is carried out to manipulate a welding electrode along the welding line determined by a design, deviations from the predetermined path in the up or down directions and right or left directions are detected by variations of the welding current, and the position of the welding electrode is controlled so that deviations are corrected.
An example of the arc sensing as mentioned above is explained hereinafter.
FIG. 1A shows an example of weaving in an automatic welding apparatus, wherein the welding groove 10 is viewed from above. FIG. 1B shows a cross section of the above welding groove 10, and FIG. 1B shows a MIG (metal insert gas) welding case, or a MAG (metal active gas) welding case. In FIG. 1B, reference numeral 11 is a gas nozzle, reference numeral 12 is a tip, and reference numeral 6 is a welding wire (corresponding to the aforementioned welding electrode) reference numeral 7 shows base materials, reference numeral 8 is a flow of a shield gas, and reference numeral 8 is a flow of a shield gas, and reference numeral 9 shows an arc. Arrows pointing to the right and to the left at the center of FIG. 1B, indicate the directions of the weaving.
Assuming that the welding electrode moves from point A to point B, then, as readily understood from FIG. 1B, when the welding electrode (welding wire 6) moves from the right and the left, the distance between the tip and the base material varies.
In MIG welding or MAG welding, welding machines with a constant-voltage characteristic are usually used, wherein the wire extension varies according to the variation of the tip-base material distance, and therefore, the welding current varies, i.e., a characteristic is shown wherein the greater the tip-base material distance, the smaller the welding current, and the smaller the tip-base material distance, the greater the welding current. FIG. 2 shows the variation of the welding current when the welding electrode is moved from left to right, e.g., from the point A to the point B shown in FIG. 1A, in the welding groove having a cross section as shown in FIG. 1B. The welding current is great in the vicinity of point A and point B, whereat the distance between the base material and the tip is small.
Next, with reference to FIGS. 3A, 3B, 3C, and 4, the process of detection and correction of deviation to the right or left of the welding electrode from the predetermined path by data of the welding current distribution for a half cycle of weaving, as shown in FIG. 2, is explained hereinafter. Only the case wherein the cross section of the welding groove is symmetric in the right and left directions (i.e., the welding groove is symmetric with respect to the bisector of the groove angle), is explained here.
First, at step 71 in FIG. 4, the welding corresponding to a half cycle of weaving, for example, from point A to point B, is carried out. Assuming that the welding electrode is at point A at a time t.sub.1, and the welding electrode is at point B at a time t.sub.2, the distribution of FIG. 2 is as indicated by FIG. 3A, where t.sub.c equals (t.sub.1 +t.sub.2)/2, i.e., t.sub.c is a half time of the half cycle of the weaving, where the half cycle corresponds to the time duration from t.sub.1 to t.sub.z, and at the time t.sub.c, the welding electrode (wire) is located above the center line of the welding groove. S.sub.L is an integral of the welding current for the duration of the welding of the left half of the welding groove, and S.sub.R is an integral of the welding current for the duration of the welding of the right half of the welding groove.
After the welding of the half cycle of weaving mentioned above is completed at step 72, if all welding processes have not been completed, the minimum value I.sub.min of the welding current detected during the half cycle of weaving, is obtained as shown in
REFERENCES:
patent: 4477713 (1984-10-01), Cook et al.
patent: 4633059 (1986-12-01), Sarugaku et al.
Kanda Yuichi
Mizuno Toru
Morikawa Shigehiro
Torii Nobutoshi
Toyoda Kenichi
Fanuc Ltd.
Shaw Clifford C.
LandOfFree
ARC sensing welding apparatus controlled by program does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with ARC sensing welding apparatus controlled by program, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and ARC sensing welding apparatus controlled by program will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-35687