CA2081514A1 - Method for monitoring weld quality in mash seam welding - Google Patents

Method for monitoring weld quality in mash seam welding

Info

Publication number
CA2081514A1
CA2081514A1 CA002081514A CA2081514A CA2081514A1 CA 2081514 A1 CA2081514 A1 CA 2081514A1 CA 002081514 A CA002081514 A CA 002081514A CA 2081514 A CA2081514 A CA 2081514A CA 2081514 A1 CA2081514 A1 CA 2081514A1
Authority
CA
Canada
Prior art keywords
weld
thickness
seam
correlation
overlap
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
CA002081514A
Other languages
French (fr)
Inventor
Jurg Schreiner
Peter Weibel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Elpatronic AG
Original Assignee
Elpatronic AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Elpatronic AG filed Critical Elpatronic AG
Publication of CA2081514A1 publication Critical patent/CA2081514A1/en
Abandoned legal-status Critical Current

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K11/00Resistance welding; Severing by resistance heating
    • B23K11/24Electric supply or control circuits therefor
    • B23K11/25Monitoring devices
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K11/00Resistance welding; Severing by resistance heating
    • B23K11/24Electric supply or control circuits therefor
    • B23K11/25Monitoring devices
    • B23K11/252Monitoring devices using digital means
    • B23K11/253Monitoring devices using digital means the measured parameter being a displacement or a position

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Length Measuring Devices With Unspecified Measuring Means (AREA)
  • Resistance Welding (AREA)

Abstract

METHOD FOR MONITORING WELD QUALITY IN MASH SEAM WELDING

ABSTRACT
When mash seam welding sheet-metal plates (11,12) with overlapping edges between roller electrodes (13,14), the quality of the weld - given that the process parameters (compressive force F of the roller electrodes, rate of advance v, current intensity I through the weld) are observed and/or controlled - is also dependent upon the width of overlap (b) of the plate edges at the weld joint. Because it is difficult to measure the actual overlap in production, the thickness (ts) of the weld seam is recorded by way of a substitute. For given workpiece data and corresponding weld parameters, this thickness is in direct correlation with the width of the overlap (b).
The functional correlation ts = f(b) can be established empirically and enables the actual value of the overlap to be calculated on the basis of the seam thickness measured.
The thickness of the seam may either be measured at the weld location by measuring the spacing of the roller electrodes (position encoder 16) or at the finished weld seam (measuring device 17). In place of the correlation ts = f(b) it is also possible to evaluate the correlation of ts with another operating parameter in analogous fashion.

Description

208~
Elpa-tronic AG, 6300 Zug (Switzerland) 91-175 METHOD FOR MONITORING WELD QUALITY IN MASH SEAM WELDING

When mash seam welding sheet-metal plates bPtween roller electrodes, for the control of the process 5 and for monitoring quality it is necessary and usual to continuously measure and/or control at least -the following operating variables:
- compressive force (F) of the roller electrodes, - rate of advance (v) and - strength of the current (I) through the weld.
The set values for these variables are - for a given workpiece - based on a certain width of overlap (b) of the edges of the plates to be welded together, and are set prior to welding while the sheet-metal plates are being aligned and clamped in place. All -the a~oresaid interdependent operating variables need to lie within certain limits in order for the reguired weld quality to be achieved.
However, "con-tinuous" measurement or control of the various operating variables while welding is in progress i5 no simple matter, and can - depending on the type of variable - present different degrees of difficul-ty. Hitherto, in order to cope, one of the methods used has been to measure, as a "redundant"
2 20~,131 variable, the weld seam -temperature of l:he workpiece as it passes tl-rough imm~diately after it leaves the roller electrodes In conjunction wi-th o-ther rea~ings, this is intended to increase the reliabili-ty of the quality monitoring function. ~lowever, in order -to be reliable, such a temperature measurement is ln turn governed by certain preconditions, or it may be difficult to install the measuring equipment, eg. an infra-red sensor, owing to the limited space available.
For the quality of the weld, or rather the formation of a satisfactory weld nugget in the seam area, it is also particularly important that the intended width of overlap is actually provided at -the welding station.
However, incorrect settings may already be introduced when the sheet-metal pla-tes are being aligned and put under load, or deviations may occur as the workpieces are being fed between the roller eleatrodes. Ye-t it is very difficult, and would appear scarcely feasible operationally (ie. during a pass) to measure the ac-tual overlap value, especially immediately ahead of the roller electrodes.
It is -the object of this invention, in conjunction with the mash seam welding process initially referred to, to propose a method suited to industrial application which allows the available options for operational quality control to be considerably expanded.
In accordance with the invention, this objec-t is achieved by recording the thickness of the weld seam duriny -the 3 2~81~1~
weldin~ operation and deriving a criterion for the ~leld quality basad on a predetermined correlatlon between the seam thickness readings and one of the - interdependen-t -operating variables ini-tially men-tioned.
There are various tried and tested ways of recording the thickness of the weld seam, and calibration presents no particular difficulties. The thickness of the seam may be measured directly or indirectly as the work emerges, or alternatively at the "point of origin" by measuring the spacing or displacement of the roller electrodes. In the latter case a correction may be required for variations in thickness that occur as the seam area solidifies and cools, but this will normally already be taken into accoun-t when the specific functional correla-tion to be used is es'tablished.
When carrying out the method according to the invention it is possible to begin by deriving a criterion by comparing the seam thickness readings with values for the other operating variables, those values having been established from the (specific utilised) predeterm:ined correlation. Alternatively, however, i-t is possible to - undertake direct comparisons of the set value and actual value for the weld seam thickness itself, the set values being specified by the said correlation.
The specific correlation u-tilised may - for given workpiece and operating parameters - be determined empirically in advance. The method according -to the invention is especially suited to operational calculation ~1 2 ~
of the actual value of ~he overlap width of the edyes of the pla-tes, which, as explained above, i-t is almos-t impossible to measure directly.
The dependent claims indicate various embodiments of the method defined in claim 1. The invention will now be explained in de-tail with the aid of examples of embodiment in conjunc-tion with the drawiny, the primary aspect being the correlation between the thickness of the weld seam and tAe width of the overlap.
Fig. 1 is a diagram showing the principle of a mash seam welding machine with roller elec-trodes and a workpiece being welded;
Fig. 2 is a schematic end view of two overlapped sheet~metal plates prior to welding;
Fig. 3 is a similar view of the pla-tes joined by the weld seam; and Fig. 4 illus-trates a typical, empirically established functional correlation between -the overlap width b and the weld seam thickness ts.
The highly simplified and schematically represented welding machine of Fig. I with its roller electrodes 13 and 14 is used for mash seam welding (a type of electrical resistance welding) sheet-metal plates 11 and 12. The sheet-metal pla-tes to be welded are aligned and clamped with their edges overlapping as shown in Fig.
2, and then conveyed at a speed v between the roller electrodes 13,14. As indicated in Fig. 1, the lower roller electrode 14 is held fixed, while the upper roller 13 can ~>e fed ollto ~lle wor1c, appl~ing a compressi~e~ e F, for example from a hydraulic cyl.inder assembly 15.
Dur.ing the ~eldiny process -the opera-ting variables -compressive force (F) of the roller electrodes 13,14, ra-te o~ advance (v~ of the work and intensity of the current (I) through the weld joint - are continuously measured and controlled as normal in a manner known per se, said : variables being based on the predetermined control s~ttiny for the overlap width b of the pla-te edges. As -the edges of the plates are welded, the passage of current between the roller electrodes and the corresponding heating of the sheet-metal material interposed therebetween in the so-called weld nugget causes -the material to simultaneously be deformed by the compressive force F, and a mash seam 10 is produced (Fiy. 3) whose thickness ts is considerably less than the sum of the plate thicknesses tl and t2 (these plate thicknesses may be different). The extent to which the material is deformed depends on the three aforesaid operating variables and the actual overlap width b (actual value) at the weld. In addition to the three said opera-ting variables, other variables such as for example the temperature of the seam lO as it emerges from between the roller electrodes may be measured during welding and controlled if the need arises.
The continuously recorded actual values of the operating variables constitute an important criterion in quality control, ie. should such actual values deviate inadmissibly it must be deduced that the weld quality is 6 2~81 ~
inadequate alld the workpiece concerned must b~ discarded.
~lowever, as stated earl~er, it is not practical to measure the actual overlap width b during -the opera-tlon. In order to be able to draw definlte conclusions about the actual value of the overlap width and henca about the weld quality of the work, the inven-tion makes use o a particular correlation between the overlap width b and the thickness ts of the weld seam 10, as depicted in Flg. 4 for one concrete example. The correlation employed between the width of overlap and the resulting seam thickness can be established empirically in advance for various workpiece and operating parameters. It has been shown that this correlation - at least in the areas relevant to production - is always unambiguous, making seam thickness an excellent substitute variable for overlap width. In other words, the thickness ts of the weld seam is measured on the workpiece and said correlation is used to determine the actual value of the overlap width b. In order to have an unambiguouY
criterion "good/reject" for the quality monitoring function, a tolerance range T may be specif:Led for the - seam thickness, to which a tolerance range B of overlap corresponds. The preceding criterion may either be derived by assessing whether the values found for b lie within -tolerance range B or no-t, or by assessing directly whether the ts values lie within tolerance range T (the se-t point range) or not.
The correlation ts = f(b) used is established in 7 208~
advance in each case us:ing appropriate series of tes-ts over the relevant range and assuming given workpiece data (plate thicknesses, material, etc) and associated operating parame-ters. Various options are possible for measuring -the thickness ts during the welding operation.
As indicated in Fig. 1, the spacing o the roller electrodes 13,14, or else the position of the feedable roller 13, may be measured automatically using a position encoder 16 (displacement transducer). However, after the work leaves the roller electrodes the seam thickness may also be measured at the solidified weld seam 10 at a point 17 using a method known per se, eg. by means of touch-contact rollers or wi-thout contact using ultrasonic or radiation absorption measurement. In either case an electric measurement signal generated by the corresponding sensors will be passed to an evaluating circuit (not shown), where the measured value will be automatically registered, displayed and evaluated for quality monitoring. When performing this evaluation it will generally bs helpEul to average the ins-tan-taneous values over the lsngth of the seam (workpiece length) or ove.r part thereof (eg. suppressing sections at the start and finish), or to evaluate them statistically for quali-ty con-trol. It goes without saying that for a plurality of workpiece and/or operating parameters -the associated functional correlations ascertained in advance will be stored in the form of data tables, thus enabling them to be called up as required for processing in a computer.

2~81~1~
~ Ithough the ~oregoillg embodi.ll1erl-ts o -the method relate -to the correla-tion be-tween weld seam -thickness and width of overlap, i.-t is also perfectly feasible to use predetermined correlations be-tween ts and other operating variables (eg. F, v, I) in similar fashion.

Claims (9)

1. Method for monitoring weld quality when mash seam welding sheet-metal plates (11,12) between roller electrodes (13,14), wherein set values are predetermined at least for the following operating variables:
- compressive force (F) of the roller electrodes, - rate of advance (v), - strength of current (I) through the weld, - width of overlap (b) of the plate edges, characterised in that the thickness of the weld seam (ts) during the welding operation is determined and a criterion for the weld quality is derived on the basis of a predetermined correlation between the seam thickness (ts) readings and one of the aforesaid operating variables.
2. Method according to claim 1, characterised in that a criterion is derived by comparing the seam thickness (ts) readings with the other operating variable determined from the said correlation.
3. Method according to claim 1, characterised in that a criterion is derived by comparing the actual and set values of the measured weld seam thickness (ts) itself.
4. Method according to claim 1, characterised in that a tolerance range ( T ) is set for the weld seam thickness (ts) reading.
5. Method according to claim 1, characterised in that the spacing of the roller electrodes (13,14) which determines the weld seam thickness (ts) is measured.
6. Method according to claim 1, characterised in that the weld seam thickness (ts) on the welded workpiece itself is measured.
7. Method according to claim 1, characterised in that the readings of the weld seam thickness (ts) are averaged and/or statistically evaluated over at least part of the seam length.
8. Method according to claim 1, 2, 3, 4, 5, 6 or 7, characterised in that a predetermined correlation between the weld thickness (ts) readings and the overlap width (b) is used to derive a criterion for weld quality.
9. Method according to claim 8, characterised in that the actual value of the overlap width (b) is determined on the basis of a correlation ascertained in advance.
CA002081514A 1991-12-16 1992-10-27 Method for monitoring weld quality in mash seam welding Abandoned CA2081514A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH3713/91A CH684467A5 (en) 1991-12-16 1991-12-16 A method for monitoring weld quality when mash.
CH03713/91-0 1991-12-16

Publications (1)

Publication Number Publication Date
CA2081514A1 true CA2081514A1 (en) 1993-06-17

Family

ID=4261912

Family Applications (1)

Application Number Title Priority Date Filing Date
CA002081514A Abandoned CA2081514A1 (en) 1991-12-16 1992-10-27 Method for monitoring weld quality in mash seam welding

Country Status (11)

Country Link
EP (1) EP0547322A1 (en)
JP (1) JPH05245652A (en)
KR (1) KR930012176A (en)
CN (1) CN1074158A (en)
AU (1) AU2705992A (en)
BR (1) BR9205017A (en)
CA (1) CA2081514A1 (en)
CH (1) CH684467A5 (en)
CZ (1) CZ363792A3 (en)
MX (1) MX9207121A (en)
SK (1) SK363792A3 (en)

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0761368B1 (en) * 1995-08-09 2000-02-02 Elpatronic Ag Welding method for coated sheets, especially tin-plated sheets
KR100275636B1 (en) * 1996-12-23 2000-12-15 이구택 Welding quality decision method
FR2800656B1 (en) * 1999-11-08 2001-11-30 Soudax Equipements METHOD FOR CONTROLLING A WELDING OPERATION IMPLEMENTED BY A SPOT WELDING MACHINE
KR100495618B1 (en) * 2000-12-19 2005-06-16 주식회사 포스코 Apparatus and method for controlling the electric power in the mash seam wealding
DE102005058588B4 (en) * 2004-12-27 2009-02-26 Joachim Zens Apparatus for seam welding a workpiece
US8803024B2 (en) * 2007-12-12 2014-08-12 GM Global Technology Operations LLC Online weld inspection and repair method for resistance welding and weld-bonding
WO2009125073A1 (en) * 2008-04-11 2009-10-15 Siemens Vai Metals Technologies Sas Position-measuring method and device adapted for the positioning of a wheel
WO2010004656A1 (en) * 2008-07-11 2010-01-14 三菱日立製鉄機械株式会社 Mash seam welding method and equipment
CN102107319B (en) * 2009-12-23 2013-09-04 沈阳黎明航空发动机(集团)有限责任公司 Method for repairing arc-seam weld porosity defects of titanium alloy sheets through hot rolling
KR101415364B1 (en) * 2010-09-24 2014-07-04 미쯔비시 히다찌 세이떼쯔 기까이 가부시끼가이샤 Mash seam welding method and device
CN109570808B (en) * 2017-09-29 2021-08-13 宝山钢铁股份有限公司 Method and device for improving weld joint quality of narrow lap welder
GB201815121D0 (en) * 2018-09-17 2018-10-31 Crown Packaging Technology Inc Welding of can bodies
JP7314680B2 (en) * 2019-07-23 2023-07-26 東洋製罐株式会社 Image data processing system, unmanned aircraft, image data processing method, and program

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8613130D0 (en) * 1986-05-30 1986-07-02 Metal Box Plc Resistance welding of can bodies
DE3711771A1 (en) * 1987-04-08 1988-10-27 Sts Systemtechnik Und Software Method and arrangement for process control in spot welding
CH677891A5 (en) * 1988-12-16 1991-07-15 Elpatronic Ag
GB8902247D0 (en) * 1989-02-02 1989-03-22 Metal Box Plc Resistance welding apparatus

Also Published As

Publication number Publication date
SK363792A3 (en) 1993-11-10
JPH05245652A (en) 1993-09-24
MX9207121A (en) 1993-06-01
CH684467A5 (en) 1994-09-30
EP0547322A1 (en) 1993-06-23
KR930012176A (en) 1993-07-20
BR9205017A (en) 1993-09-14
CN1074158A (en) 1993-07-14
AU2705992A (en) 1993-06-17
CZ363792A3 (en) 1993-09-15

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