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Apart from structural elements, a wide vari-ety of laminar precast concrete elementshave been manufactured for many years atthe location in Siegen; the range extendsfrom simple solid walls to sophisticatedfaade elements with a sandwich designthrough to custom parts for large tanks, bio-gas plants and the like.In addition, Drssler has considerablyextended its production range in recentyears.

For instance, the company has developedits own patented construction system for themanufacture of so-called Ventur hybrid tow-ers, with which particularly efficient windturbines up to 160 m in height can be man-ufactured. The tower segments required forthis are likewise manufactured from laminarsolid elements with outer toothing for con-nection with one another.In order to meet these demanding require-ments, the existing production has been

modernised and replaced by a highly flexi-ble pallet circulation plant with a centralmoving platform.

Planning/building phase

Drssler had already begun to considerextending the existing plant in 2012. All themore so after it became apparent that thenewly developed wind turbine towers hadalso been successfully accepted by themarket and would result in an extensivefield of activity for the coming years.

The Prilhofer Consulting planning officefrom Freilassing was commissioned todevelop an appropriate concept. Themajor task was to improve the post-treat-ment of self-compacting and high strengthconcretes by means of hardening chambersin a newly planned hall, but with undimin-ished flexibility in the use of the plant.Beyond that, the existing hall with the con-

Start of production of a highly flexible pallet circulationplant for Drssler in Siegen, Germany

Avermann Maschinenfabrik GmbH & Co. KG, 49078 Osnabrck, Germany

After many years of manufacturing precast concrete elements on tilting tables and stationary production lines, Benno Drssler GmbH & Co.Bauunternehmung KG of Siegen decided to optimise the proven production by the use of a pallet circulation plant. The concept was speci-fied with all detail requirements in autumn 2013, after which tenders were invited and quotations obtained from various plant manufactur-ers. The Avermann company was awarded the contract for the delivery of the pallet circulation plant in a package together with its subcon-tractor SAA Engineering, which supplied the process and circulation controller with control system.

Patented Ventur hybrid tower for wind turbines

3D general view of the plant

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Your projects our machineswww.avermann.com

since 1946

AVERMANN Maschinenfabrik GmbH & Co. KGLengericher Landstr. 35 49078 Osnabrck/Germany

Phone: +49 5405 505-0 Fax: +49 5405 6441 info@avermann.de

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crete and reinforcement delivery was to beused further and the process of removal tothe outdoor storage area was to be stream-lined.

Due to these requirements as well as thevaried production range, a classic pallet cir-culation plant principle was out of the ques-tion. Therefore planning was concentratedon a pallet circulation plant with a centralmoving platform.

The concept was specified with all detailrequirements in autumn 2013, after whichtenders were invited and quotationsobtained from various plant manufacturers.As a result of the sounding-out/negotia-tions, the Avermann company was award-ed the contract for the delivery of the palletcirculation plant in a package together withits subcontractor SAA Engineering, whichsupplied the process and circulation con-troller with control system.

For the new plant the existing Hall 3 had tobe cleared out and appropriate alterationshad to be made with pits and the like, inparticular for the operation of the movingplatform. An additional new hall was erect-ed for the hardening and removal area.

The construction work, with the requiredearth moving and foundation work, hallconstruction, etc., was then carried out byDrssler itself from spring onwards, allow-ing installation of the plant to commence atthe end of May. Commissioning took placeaccording to plan, step by step and underspecial conditions, since Drssler alreadyhad to produce during the plant assembly.First of all the equipment in the existing hallwas assembled and put into operation, thenthe machines with the storage and retrievalmachine for feeding the hardening cham-ber were completed and the automaticoperation was set up.

Plant concept with production equipment

The plant is designed for the production of33 pallets with dimensions of 10 x 4.5 mand a load-bearing capacity of 10 kN/m.The maximum payload per pallet is 320kN.

All precast elements up to max. 500 mmwere defined as standard component thick-nesses; there is space in a hardening cham-ber compartment for each pallet with theseelements. Beyond that, however, customelements up to 1,200 mm in thickness canalso be driven into the plant and stored inthe hardening chambers. In this case eachone occupies two compartments at thesame time.

Expandability of production at a later dateby the retrofitting of additional pallets andhardening chambers is technically possible,but is not planned at present.

The hardening chamber area consists ofthree racks, each with 11 hardening com-partments. The hardening chambers areindividually insulated and can be heateddifferently, so that in particular the specialrequirements for the Ventur production aremet. The optimised feeding of the harden-ing chambers takes place from above by astorage and retrieval machine.

After the fully automatic removal from stor-age this area is accordingly secured bymeans of fences and by light barriers/mut-ing system the pallets with the hardenedconcrete elements are pre-demoulded atthe two processing stations and transported

Storage and retrieval machine for hardening chamber feeding

Central moving platform with cross-lifting truck at the entry to the compaction station

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SAA Engineering Automation Technology for Concrete Precasting Plants

SAA Engineering GmbHGudrunstrae 184/4, A-1100 Vienna

www.saa.at T: +43 1 641 42 47-0

Whenever Man and Machine workHand in Hand

onwards to one of the two tilting stations,where the elements are lifted off by the hallcrane.

After having been lifted off, the parts areusually temporarily stored in the hall, fol-lowed by appropriate post-treatment, cos-metics, etc. Removal for storage in the out-door area takes place later. This is doneusing a special run-off truck with a load-bearing capacity of 60 t for longitudinaland transverse transport, usually allowingtwo elements to be transported to the out-side simultaneously on suitable frames. Theconcrete elements are either set down onbearing blocks in the outdoor store orbrought directly under the gantry crane forimmediate transfer.

After the precast elements have been liftedoff, the empty pallets are transported out ofthe hardening/removal area into the pro-duction hall. Here a fully automaticallyoperated central moving platform takescare of the further transport tasks.Due to the different processing procedures,the Ventur production there is a small, pal-let circulation plant at the rear end of thehall for this and the rest of the productionare separated at Drssler.

All shuttering and reinforcement work forthe solid/sandwich walls and custom ele-ments now takes place on the stations locat-ed in front of the central moving platform.The most diverse tasks can thus be per-formed in parallel and without mutual inter-ference, independent of the actual scope

and duration of the work. Normally theshuttering work is carried out on the twofront workstations and the reinforcementwork on those at the rear, but this can behandled with complete flexibility, depend-ing on the work schedules, bottlenecks, etc.The element reinforcement is prefabricatedin a separate hall at Drssler and deliveredto the reinforcement stations in relation tothe specific pallet for further installation. Allwork for the Ventur production is carried

out at the rear stations. Hence, there is noinfluence on the rest of production. For thesame reason concreting also takes place inseveral places.

Normal concrete is also processed in addi-tion to self-compacting concrete (SCC). Aconcrete distributor with a bridge design isavailable for this; it is fed by a bucket trackand serves two workstations. Including vari-ous additional items of equipment on the

PRECAST CONCRETE ELEMENTS

Fig. 5: Shuttering and reinforcing stations for solid/sandwich walls and custom elements

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concrete distributor lowerable internalspud vibrators are installed here amongstother things and the HF compaction stationinstalled at one station, all specified con-cretes can be discharged and compacted.

A height-adjustable levelling device isattached to the concrete distributor bridgefor the direct smoothing of the top side ofthe concrete elements.

At the end of the production sequence thestorage and retrieval machine is called intoaction once more. In accordance with spec-ified sequence schedules the freshly con-creted pallets are placed in