| 54 |
Title |
TI |
[DE] Verfahren zur Sicherung der Schweißqualität von Schweißpunkten beim Widerstandspunktschweißen einer bestimmten Materialkombination
[EN] Protecting the welding quality of spot-welds during the resistance spot welding of predetermined material combination, comprises determining the change of tongs clamping force of welding tongs over welding time for each welding points |
| 71/73 |
Applicant/owner |
PA |
INPRO Innovationsgesellschaft für fortgeschrittene Produktionssysteme in der Fahrzeugindustrie mbH, 10587 Berlin, DE
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| 72 |
Inventor |
IN |
Berg, Martina, 10587 Berlin, DE
;
Kraska, Martin, 14558 Nuthetal, DE
;
Niedergesäß, Ulf, 10247 Berlin, DE
|
| 22/96 |
Application date |
AD |
Jan 15, 2008 |
| 21 |
Application number |
AN |
102008005113 |
|
Country of application |
AC |
DE |
|
Publication date |
PUB |
Oct 1, 2009 |
33
31
32 |
Priority data |
PRC
PRN
PRD |
|
| 51 |
IPC main class |
ICM |
B23K 11/36
(2006.01)
|
| 51 |
IPC secondary class |
ICS |
B23K 11/10
(2006.01)
B23K 11/24
(2006.01)
|
|
IPC additional class |
ICA |
|
|
IPC index class |
ICI |
|
|
Cooperative patent classification |
CPC |
B23K 11/115
B23K 11/255
|
|
MCD main class |
MCM |
B23K 11/36
(2006.01)
|
|
MCD secondary class |
MCS |
B23K 11/10
(2006.01)
B23K 11/24
(2006.01)
|
|
MCD additional class |
MCA |
|
| 57 |
Abstract |
AB |
[DE] Die Erfindung betrifft ein Verfahren zur Sicherung der Schweißqualität von Schweißpunkten beim Widerstandspunktschweißen einer bestimmten Materialkombination, bei dem für jeden Schweißpunkt p der Verlauf der Änderung der Zangenschließkraft F über die Schweißzeit tS, bezogen auf eine zu Beginn der Schweißzeit tS gegebene Referenzkraft FREF, ermittelt und der jeweilige Schweißpunkt p als "in Ordnung" (i. O.) bzw. "stabil" klassifiziert wird, wenn zum einen der ermittelte Kurvenverlauf der Änderung der Zangenschließkraft F über die Schweißzeit tS vor deren Ende eine maximale Kraft FMax und am Ende der Schweißzeit tS eine Kraft FEnd aufweist, die kleiner als die maximale Kraft FMAX', jedoch größer als die Referenzkraft FREF ist. Erfindungsgemäß ist unmittelbar nach Ende der Schweißzeit tS der Durchmesser DL der Schweißlinse jedes als "in Ordnung" (i. O.) bzw. "stabil" klassifizierten Schweißpunktes p der vorgegebenen Materialkombination nach der Formel DL = a + bfmax + cfend zu prognostizieren, wobei die Koeffizienten a, b und c zuvor über Referenzschweißungen durch Approximieren an den jeweiligen als "in Ordnung" (i. O.) bzw. "stabil" klassifizierten Schweißpunkt p ermittelt werden, indem der Durchmesser DL der Schweißlinse meßtechnisch erfaßt wird, der ermittelte Durchmesser DL der Schweißlinse dann in einem dreiachsigen Diagramm mit den Koordinaten DL (mm); fmax und fend den Werten für fmax und fend des jeweiligen ...
[EN] The method comprises determining the change of tongs clamping force (F) of welding tongs over welding time (t s) for each welding points (p) of a material combination (5), where the welding time is related to a reference force (F r e f) given to begin the welding time and the welding points are provided with the welding tongs and classifying the respective spot-weld (p) of the material combination as normal and/or stable, when the determined curve shape of the change of the clamping force has a maximum force (F m a x) before their end and a force (F e n d) at the end of the welding time. The method comprises determining the change of tongs clamping force (F) of welding tongs over welding time (t s) for each welding points (p) of a material combination (5), where the welding time is related to a reference force (F r e f) given to begin the welding time (t s) and the welding points are provided with the welding tongs and classifying the respective spot-weld (p) of the material combination as normal and/or stable, when the determined curve shape of the change of the clamping force has a maximum force (F m a x) before their end and a force (F e n d) at the end of the welding time (t s), where the force (F e n d) is smaller than maximum force (F m a x) but larger than the reference force (F r e f), and when the spot-weld (p) of the material combination is formed with a predetermined strength of the welding current (I s) over the welding time (t s) in a spatter-free manner. The thermal stretch of a system causing the change of the clamping force is overlaid by sinking welding caps (12) into the welding material. After the end of the welding time, the diameter (D l) of the weld point is prognosticated as normal and/or stable classified spot-weld of the given material combination by the condition D l=a+bf m a x+ cf e n d, where: f m a xis relative maximum force (F m a x) related to the reference force (F r e f); f e n dis relative force (F e n d) at the end of the welding time related to the reference force (F r e f); and a, b and c are coefficients. The coefficients (a, b and C) are determined over reference welds of the certain material combination for the welding task by approximating the respective normal and/or stable classified spot-weld, so that the diameter (D l) of the weld point is determined by measurement techniques. The determined diameter (D l) of the weld point is assigned in a three-axis diagram with the coordinates D lmm, f m a xand f e n dto the values for the respective spot-weld under formation of an arrangement of point cloud. A level in the arrangement of point cloud is stretched by the approximation and from that position the coefficients are determined. A readjusting depth delta d of the welding caps and/or the change of the metal sheet force of the given material combination in the respective classified spot-weld and/or the remaining thickness of each spot-weld from the force signal, which is assigned as stable classified spot-weld, are determined according to the prognosis condition delta d=a+bf m a x+cf e n d. The readjusting depth is determined by the measurement of the remaining point thickness of the spot-weld. The determined readjusting depth (delta d) of the weld point is assigned in a three-axis diagram with the coordinates delta d, f m a xand f e n dto the values for the respective spot-weld under formation of an arrangement of point cloud. A transverse cross section represents in the welding plane to determine the diameter (D l) of the weld point and the readjusting depth delta d at each weld point by the measurement of the edges of structure of the weld point and/or the remaining thickness of each spot-weld. The clamping force of the propelled welding tongs is measured by piezosensors (6) arranged at a tong arm (2) of the welding tongs. The welding tongs are servo-motorically, pneumatically or hydraulically propelled. |
| 56 |
Cited documents identified in the search |
CT |
DE000002362520A
US000004419558A
US000005892197A
|
| 56 |
Cited documents indicated by the applicant |
CT |
|
| 56 |
Cited non-patent literature identified in the search |
CTNP |
WTC-Datenblatt: ML 00273-Rev.1.2, May 2003, Farmington Hills, MI USA p 0
|
| 56 |
Cited non-patent literature indicated by the applicant |
CTNP |
"Welding Technology Corporation" Data Sheet :ML00273-Rev 1.2, Mai 2003 1;
DVS-Merkblatt 2916 "Prüfen von Punktschweißungen", Teil 3, Seite 2 1
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Citing documents |
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CN000103894746A
CN000105772922A
DE102013217583A1
DE102013217584A1
US000009884386B2
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Sequence listings |
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Search file IPC |
ICP |
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