christian prilhofer consulting, 83395 freilassing, germany ... · precast concrete elements cpi –...

Skanska and ModernaHus

Skanska is one of the worlds largest con-struction companies, with a leading posi-tion in a number of home markets inEurope, the United States and LatinAmerica. Skanska also carries out projectdevelopment in selected geographic mar-kets and focuses on finding innovativesolutions through close collaboration withits customers and by combining theGroup’s international expertise with alocal presence.

In Skanska Sweden strategic work withdeveloping a more effective constructionprocess is always ongoing. As a part ofthis program an increased level of industri-al construction techniques are beingadopted. Product platforms, such asModernaHus, a residential apartment

building concept are being developed,which enable Skanska to repeat andimprove, lower the costs and improve thequality.

Part of the improvements is done bymoving working hours from the temporaryconstruction sites to a more controlledenvironment within a factory. Through theinvestment in a new pallet circuit inSträngnäs, Skanska aims to increase bothcapacity and efficiency with an improvedworking environment and better quality ofthe pre cast products used at Skanskasconstruction sites.

New pallet circuit

The new pallet circuit is built around a cen-tralized curing chamber with 6 towersand 10 levels each. The maximum useful

height for concrete elements per level is400 mm but elements up to 1.000 mmcan be produced and stored in compart-ments of the curing chamber. The size ofthe steel pallets is 12.50 x 4.50 m. Themaximum weight of concrete elements tobe handled in the pallet circuit is 24 tons,considering a load of 750 kg/m2.

Pallets are transported with the help of rollers and friction wheels in longitudinaldirection. In transversal direction the trans-port is done by pairs of cross lifting trucks.The workstations for set up side moulds,inserts and reinforcement are located ona special mezzanine and operated bytwo pairs of cross lifting trucks with speci-al lifting device. These lifting devices areable to lift the pallets for 2 meters. Thesestations are the main manual workstationsin the pallet circuit and located on a mez-

New pallet circuit and modernization ofthe existing production plant at Skanskain Stängnäs, Sweden

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PRECAST CONCRETE ELEMENTS

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Christian Prilhofer Consulting, 83395 Freilassing, Germany

A general renewal of the Skanska factory inSträngnäs was done which includes a new palletcircuit and the modernization of the existing pro-duction plant. The possibilities of including thepallet circuit in the existing facilities and a newfactory building was checked. The decision wasmade to build a new building for the pallet circuit

system and to use the existing building for up-grading the production of reinforcement, specialproducts like facades and pre stressed parts.The pallet circuit system was designed to producesandwich elements, solid walls, solid floor slabsand special elements with a maximum height of3.800 mm and a length of 12.000 mm.

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Placement of the side moulds, supported by a laser system

1a 1b

05a-Fertig_142-_en.qxp 12.06.2007 8:53 Uhr Seite 184

zanine with a level of about 3.3 meters. The mezzanine has ope-nings according to the pallet size. The pallets are lifted into theopening by the cross lift trucks and placed on interlocking de-vices. If no pallet is placed a telescopic railing is lifted up and pre-vents the workers from accidental falls.

The stations are accessible from underneath. Pallets can overtakeeach other by passing underneath the mezzanine. Therefore thestations are fully flexible and complicated elements which requireintensive preparation and long working time do not negativelyinfluence the flow of production for other products. The two pairsof cross lifting trucks transport the pallets in full automatic mode.The workers just have to press the button for lifting the telescopic


www.cpi-worldwide.com CPI – Concrete Plant International – 3|2007

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Preparation of the pallet; cleaning, oiling and placement of thereinforcement

2b

• Precast Concrete Drawing, Planningand Manufacturing Software

• Prestressed Hollowcore ManufacturingSystems

• Computer-Controlled Bed Plotters,Notch Suction Machines and Saws

• Mechanical Insertion of Lifting Hooks in Prestressed Hollowcore

• Production of Precast Walls

• Precast Concrete Handling Systems

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railing into the top position. Further pallettransports are done fully automatic andthe workers can immediately continueworking at the next pallet which has beenplaced in the meantime.

This system guarantees full flexible andeffective working (as the workers do nothave to wait during pallet exchange) andthe highest level of labour safety because

there are no pallet transports longitudinalor transversal in the working area. Thepallets are easily accessible for the wor-kers because the pallet surface is nearlyon the same level as the mezzanine floor.The most used material can be storedclose to the pallet stations.

After the hardening process is finished thepallets with the pre cast elements are

taken out of the curing chamber and ademoulding crane removes and placesthe side moulds onto a conveyor belt. Theshutters are transported to a cleaning andoiling device especially for shutters withintegrated magnets. After all moulds havebeen removed the pallet is transporteddirectly to the tilting station.

The pallet circuit can be equipped at alater stage with a special shuttering robotsystem for removing and placing of theshutters on the pallet.

At the tilting station the elements are liftedfrom the pallet with the help of two over-head cranes and a special beam. The ele-ments are brought to the completion areawith several finishing stations where thecompletion of the elements (painting,inserting windows, etc.) is done. After thatthe elements are put onto transport racks/trailers which are brought to the stock-yard by means of a truck. After demould-ing and cleaning by an automated clean-ing machine. After this procedure the pal-lets are ready for a new production cycle.

Concreting is done manually or in auto-matic mode. The supply of concrete is car-ried out by a concrete shuttle that con-nects the spreader and the batching plant.After concreting and compacting differentprocesses start. Solid walls and floor ele-ments will be screeded. Solid walls arepower floated on special stations on topof the curing chamber when the adjust-able pre curing time is over. After finishingthese processes on the solid elements theyare transported into the curing chamber.

Sandwich elements require more effort.When the reinforcement for the 1st layeris placed in the set up side moulds the pal-let is transported to the concrete spreader.The first layer is cast and compacted. Thepallet is transported to the insulation stati-on where the insulation is placed. Nowthe pallet must go in a smaller loop backto the reinforcement stations on the mez-zanine to get the second part of the rein-forcement and after that the pallet ismoving back to the concrete spreader toget the second layer of concrete.

Depending to the type of element a treat-ment of the surface is made. Screeding onall elements and on some power floating.


186 CPI – Concrete Plant International – 3|2007 www.cpi-worldwide.com

Concrete spreader

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Storing of the pallets in the curing chamber

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The control system of the pallet circuit is a very important part ofthe whole set up.

The work-plan of a product includes the way a product has totake through the plant. This is necessary that the transports can bedone in automatic mode.

The control system of the pallet circuit is an important part of thewhole set up. It consists of the master computer system LEIT2000and the PLC-control for the pallet circuit (pallet transports, rackfeeder, concrete distributor, pallet cleaning device, tilting table),

Tilting station

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Finishing of the wall elements

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These laser projectors can be operated from a mobile position on rails or form a stationary position. Production data for the precast concrete component can be displayed simply by thepress of a button.

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which interact via working-plans. A wor-king-plan of a product describes the waya product has to take through the plant. Itconsists of working steps for each of it alist of stations is configured, where thiswork can be performed (e.g. shuttering,reinforcing, screeding, etc.). When theoperator presses the button for havingfinished his work on the actual pallet, themaster computer calculates a free stationaccording to the next step in the workingplan and submits a transport command tothe circuit control.

By means of that mechanism the track of apallet and the needed labour time is clear-ly reported by arrival and departure timesand the transports can be done in auto-matic mode.

At the shuttering and preparation stations,which are equipped with laser projectors,the master computer transfers the rightdata for displaying element contours,insert parts and cut-outs.

At the demoulding station a label withbarcode is printed automatically for eachelement, when the pallet arrives from thecuring chamber. This enables a furtherbooking of element states in the comple-tion area. By means of wireless barcodereaders, an operator there sets an ele-ment to the “finishing”-status, when hestarts with completion (painting, insertingwindows, etc.). Before transporting it tothe stockyard he books the “ready fordelivery”-status. These element states aresubsumed to an aggregate status of theorder, which is used for disposal and de-livery planning. Via database interfacethe superior ERP-system has online-accessto the status-data.

Conclusion

The design of the pallet circuit was donein this special way to guarantee the bestcombination between efficiency and flexi-

bility for the complex sandwich and solidwall elements as well as to meet the highhealth and safety standards from Skanskaand the Swedish authorities.

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7a 7b

At the stockyard the elements are handled with several gantry cranes

Owner:

Skanska Sverige ABConstruction Frame SystemsRåsundavägen 2169 83 Solna, SWEDENT +46 8 50435000, F +46 8 [email protected]

Christian Prilhofer ConsultingPommernstr. 1783395 Freilassing, GERMANY T +49 8654 69080F +49 8654 [email protected] www.prily.com

Sommer Anlagentechnik GmbHBenzstr. 184051 Altheim, GERMANY T +49 8703 98910 F +49 8703 [email protected]

saa engineering gmbhGudrunstr. 184/ 5/ 21100 Wien, ÖSTERREICHT +43 1 64142470F +43 1 641424721

[email protected]

SL Laser GmbHMunastr.1083301 Traunreut, AUSTRIA T +49 8669 863811F +49 8669 [email protected]

Weckenmann Anlagentechnik GmbH & Co. KGBirkenstraße 172358 Dormettingen, GERMANY T +49 7427 949320F + 49 7427 [email protected]

Designer:

Manufacturer:

Manufacturer:


christian prilhofer consulting, 83395 freilassing, germany ... · precast concrete elements cpi –...

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