“FRO : NEW CONCEPT OF WELDING”

“II International Conference on Steel Construction – II CICOM”

“FRO : NEW CONCEPT OF WELDING” (1)

Filippo Colucci (2)

Abstract:FRO belongs to the multinational group Air Liquide, employs 850 people and owns sixmanufacturing plants for flux, electrodes, wire, flame cutting and welding, welding machinesand welding automation.The purpose of the presentation is to deeply expose the current technology for the followingapplications in Steel Construction :

1) Beam welding in vertical position : general layout of such solution, typical weld able sections (T/I–shaped), procedures, advantages, productivity, grade of automation.

2) Beam welding in horizontal position: a) solution with column and boom + assembly jig b) H-Master For both solutions : general layout, typical weldable sections (H–shaped), procedures, advantages, productivity, grade of automation c) Flange straightener

3) Other equipment for beam handling and welding

4) Bridge manufacturing (panels-troughs)

5) Shipbuilding – procedures and complete welding lines for: a) Fabrication of flat panels and blocks (panel lines, minipanel lines) b) vertical welding of cells c) Welding of curved blocks d) Latest research programs (laser and hybrid laser technology, etc.)

6) Welding of cylindrical pieces (reservoirs, tanks, pipes, etc.) – different procedures (Subarc, MIG, TIG, plasma).

7) Compressors for refrigerators and other applications.

Key-words: Automatic Welding Fixtures and welding lines

-----------------------------------------------------------------------------------------------------------------(1) - Technical Contribution to be submitted to the “II International Conference on SteelConstruction – II CICOM” – November, 2002 – São Paulo, SP, Brazil.(2) -.

“Il International Conference on Steel Construction – II CICOM”

1- T / I-BEAM WELDING

There are two different solutions to weld the T or I beam: web in vertical position (during thewelding) and web in horizontal position.

1.1- Vertical PositionThe Beam is welded without needing of tack-weld except at the leading edge, after the webhas been aligned in the center line of the flange.It is possible weld different shape of T-Beam depending on the request of the customer.Common values could be summarized in the following table.

Table I: Indicative Dimensions of the beam to be welded

H a b e L

MIN 200 4 100 6 6000

MAX 4500 75 1600 100 24000

The beam is fed vertically through the welding machine and two fillets are welded at the sametime. The contact between web and flange is ensured by the hydraulic traverse that appliespressure to the beam during welding. The pressure is adjustable according to web thickness.The traverse also includes the top guide roll for the web. A drive rolls system permits to feedthe beam during welding; the drive rolls give a variable speed ranging from 0.2 to 2 m/min.Two columns, bolted to the base, include machine guides for the vertical ram, and on whichare mounted the wire feeders, wire reels and flux hoppers. The welding nozzles are mountedon slides for positional adjustment.At the exit is installed the straightener to compensate the angular distorsion of the flange up to25 mm. max thickness (not needed for higher thicknesses).The complete line includes also an in-feed conveyor and out-feed conveyor with variousdegrees of automation; hydraulic tilters assist in web loading and beam unloading.After completion of the first flange welding, the section is turned through 180° by the tiltersand the alignment and welding operation repeated with the second flange so that it is possibleto obtain I-beam.


Figure 1 – Layout.

Figure 2 – Welding Machine and In-feed line.

1.2- Horizontal PositionThe welding with web in horizontal position is done depositing two fillet weldssimultaneously.Tack welding is required only at the leading edge of the beam.It is possible weld different shape of H-Beam depending on the request of the customer.Common values could be summarized in the following table.


Table II: Indicative Dimensions of the beam to be welded.

It includes a sturdy frame on which are mounted the feed rolls operating on the two flanges invertical position. One side of the unit is the datum, while the other operates bymeans of the hydraulic cylinder powered from a separate station. The roll surfacesare hardened for maximum wear. The rolls are powered by motor gear reducers,capable of feeding the beam at adjustable speed. Thetravel of the movable side covers the full range of beam sizes. On each side of thewelding machine are located two pairs of flange guides, ensuring perfect alignment ofthe beam components during welding.The web is supported by special rolls, one in fixed position, while the other isintegral with the movable side the machine to ensure a proper support accordingto the web height.The machine is designed to allow the level adjustment according to the flangewidth; to this purpose a proper frame, lift able by screw jacks, plus other jacksensuring the support when handling beams having different flange width areprovided. Automatic submerged arc equipment for twin-arc or single wire. The machine issupplied complete of mechanical auto guidance system and fluxrecovery system for continuous flux re-circulation.

Figure 3 – Layout.


Figure 4 – Welding Machine and In-feed line.

The productivity of the machine is roughly 40 beams each 8 hours shift (length 8/10 m)welded on one side.

2- STRAIGHTENER

Such machine is suitable to straighten flanges having the indicative followingdimensions:- min./max. web height : 200 ÷ 2.000 mm.- min./max. flange width : 100 ÷ 200 mm.

- min./max. flange thickness : 15 ÷ 20 mm.- max beam length : 20 m.The machine is mainly composed by a base frame where two columns supporting thestraightening device are mounted.One column is fixed, while the other one is adjustable on the base frame according to the webheight by a hydraulic cylinder.Straightening is carried out by two bending rollers that press the flanges to recover thedeformation produced during the previous welding process; the reaction to the force operatedby such rollers is provided by two central rolls (one for each column) driven by twoindependent electric motors (synchronised) also ensuring the beam feeding.Idle guidance wheels are also provided to support the beam.The drive rollers are mounted on supports with vertical slides adjustable by handwheel.The rollers provided for flange straightening are connected to hydraulic cylinders and aremounted on eccentrics to suit different flange thicknesses.The position of the two top straightening devices can be vertically adjusted by hand wheeltoo. The two lower rollers are fixed. Hydraulic station and control unit included.Advancement speed : 3 m./min.


Figure 5 – View of straightener

3- BRIDGE MANUFACTURING

A Special station allows to weld troughs (in this example three simultaneously) on a panel.This machine is suitable for building of bridges.General view of a troughs welding system sold in U.K including:- Column and boom multiple head welding machine- Tacking press- Assembly jigDimensions:Max. panel size : 18 x 3.5 mMax. number of troughs : 5


Figure 6 – Cleveland Bridge Application.

4- SHIPBUILDING : PROCEDURE AND COMPLETE WELDING LINE

The Panel Line is designed according to the basic concept of "NO TACKWELDINGREQUIRED", both for the One Side Welder and for the Stiffener Positioning and WeldingSystem.


Figure 7 – Panel Line Layout.

The Panel Line is manly composed by:- Conveyors- One Side Welding- Stiffener Positioning and Welding- Webs Mounting and Welding- Transport and lifting devices

4.1- One Side WeldingThe majority of the shipyards all around the world is equipped with a one side welding toweld flat panel.Such machine is specially designed to weld panels for shipbuilding using the one-sidewelding procedure in submerged arc together with a water-cooled copper backup bar.It is suitable for the one-side welding without tack-welding of ship panels having thicknessvariable between 4 and 35 mm.The plate support with adjustable height and the special copper backing arrangement make itpossible to weld plates with different thickness maintaining the even surface of the panel atthe top.The clamping of the plates to be welded is carried out by means of two series of hydrauliccylinders (one for each side of the machine), applying a maximum working pressure of 6T/meter each side.The plates are loaded by crane on the in-feed conveyor and are then fed into the machine,where are aligned by means of special hydraulic side aligners and properly positioned bymeans of powered positioning stops.These positioning stops (two series one for each side) are housed in the machine's frame andhave adjustable position on one side to set the gap between the plates according to thethickness to be welded.This machine is able to execute high quality fillet joints allowing at the same time a toleranceof 4 mm. on the nominal joint gap.The welding equipment is mounted on a carriage traveling along the machine length andincludes three welding heads in a.c. and two power sources.


On the same carriage are also mounted the laser guidance system and the unit to automaticallydeposit/recover the flux from the copper bar.This welding procedure matched with the machine allows one-side welding in only one passensuring at the same time a percentage of defects lower than 1%.Since the machine does not need tack-welding, only one operator is necessary for its working.

Figure 8 – One Side Welding and Turning Rolls Station.

4.2- Stiffener Positioning and WeldingThe basic panel line also includes a station for positioning and welding of the stiffener. Two alternatives can be proposed:

1) Solution without need of tack welding2) Solution needing tack welding of the stiffeners

1) It is a special station designed to pick up, handle, position and welding the stiffener.The handling cycle is fully automated and controlled by PLC. Tack welding of stiffeners isnot needed. The station includes:- Mobile Stiffener Positioning Gantry- Welding Gantry (fixed)- Pre-deformation device


This station is suitable to position and weld stiffeners with the following types: • bulb profile • flat bar • L/T-profile The stiffeners are in a container placed on a fixed bridge across the line in the same sequencerequired on the panel. The mobile gantry picks up one stiffener at a time and handle/positionit under the welding gantry with an automatic cycle controlled by a PLC.Welding of stiffeners in submerged arc is carried out simultaneously on both sides of thestiffener. On the gantry are also arranged flux recovery units and cables holders.The Welding Gantry can be provided with a device suitable to pre-bend the panel tocompensate the angular deformation that will be produced during the welding phase.The system includes a number of magnets (or alternatively suction caps) along both sides ofthe Welding Gantry basement.The magnets are lifted by hydraulic cylinders against the bottom surface of the panel.By activating the magnets it is then possible to provide on the panel a camber opposite to theangular deformation produced by welding. Lift able wheels are also provided to ease the paneltransfer after each welding cycle.

Figure 9 – Stiffener welding gantry.

2) The second solution needs tack welding of the stiffeners; in such a case the WeldingGantry can weld three stiffeners at a time. Are included: - Floor equipment for stiffener mounting and welding - Stiffener Mounting and Tackwelding Gantry- Stiffener Welding GantryThe Stiffener Mounting gantry is suitable for positioning, clamping and tackwelding of thestiffener on flat panels. The stiffeners are stored in a container placed on a fixed bridge across the line in the samesequence required on the panel.The gantry, suitable to pick up the stiffener from the container and position it along themarking line on the panelThe Stiffener Welding Gantry is a double gantry composed by a carriage supporting a beamwith machine guides where are mounted N. 3 groups


supporting the welding heads, which position is manually adjustable to comply with thedistance between two stiffeners.Welding is done simultaneously on both sides of the stiffeners (alternate stiffeners).The fixture is also provided with a alarm system with a PLC controlling the sequence ofheads clearing at the end of welding and monitoring lack of wire or welding breakdown inone of the torches (program for stick welding not included).

Figure 10 – Stiffener Mounting and Welding Gantry.

4.3- Web Mounting and WeldingThe final station to fabricate a block includes gantries for webs mounting and welding.The Mounting and Tack welding Gantry is a special gantry suitable for positioning and tackwelding of the webs on the base panel.The top beam of the gantry is provided with slides for the travel of the trolley supportingthrough a powered lift able hoist properly designed crab frame for positioning, clamping andtack-welding of the web.The tight contact between web and base panel before tack welding is granted by using thepanel clamping device mounted on the same groupWeb tack welding is done by N. 4 MIG Semiautomatic Welding equipment; they are mountedon hoists supported by two trolleys traveling on guides placed on the top beam and lockablein a fixed position.The Welding gantry is equipped by N. 6 articulated arms that are fixed to the top beam of thegantry and each one is provided with a hoist supporting one semiautomatic weldingequipment.The arms are movable in all directions and are also provided with a hydraulic cylinder to easepositioning and clamping.


Figure 11 – Web Mounting and Welding.

5- WELDING OF CYLINDRICAL PIECES

5.1- Tanks WeldingAn exemple of such application is the welding fixture designed for the automatic submergedarc welding of large diameter storage tanks. With this fixture the horizontal joints can bewelded in the three o’clock position both inside and outside simultaneously if required.The fixture is supported by the plates to be welded and travels along the upper edge by meansof a carriage driven by a DC motor and variable speed gearbox giving a speed range of 0.15 to1.5 m/min.Indicative Tank dimensions:

- Minimum weld able Diameter 6 m- depth of plate 1300 – 2500 mm- plate thickness 8 – 40 mm.

The fixture consists of a sturdy tubular steel framework incorporating operator’s cabin.The upper part of the fixture is bolted to the travel carriage, which can be positioned atdifferent heights according to the depth of the plate.The powered carriage consists of two knurled driving wheels connected by a drive shaft andtwo pairs of conical rollers clamping the edge of the plate.The system allows the fixture to accommodate tanks of different diameters and platethickness.The head is mounted on a system of slides. The flux supporting belt, which is made ofneoprene, is placed under the head and is kept in contact with the plate by a spring loadedroller. The cabin is supplied with a protective cover.The same fixture can be used for vertical welds by installing inside the frame a weldingcarriage for CO2 or cored wire traveling on a vertical rail.


Figure 12 – Tank Welding Machine : Details.

5.2- Pipes WeldingColumn and booms for big size pipe welding, turning rolls, table positioners seam welder andallows to weld all range of pipes

Figure 13 : Column and boom , Seam welder.


6- COMPRESSOR FOR REFRIGERATORS

Each line is essentially composed by :- conveyor system for the movement of compressors.- n.1 unit for assembly and TIG tack welding of compressor.- n.3 units for MIG welding (double torches) of compressor.According to applications, equipment can weld with torches in vertical position or in threeo’clock position.

Figure 14 – Details of the compressor after TIG Tack Welding.

Figure 15 – TIG Tack welding machine (3 Torches) and centring device for the coverautomatic piece feeding by conveyor system - PLC controls operating cycle.

“FRO : NEW CONCEPT OF WELDING”

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