Each of the concrete block machines is supplied with concrete from a separate mixing and batching plant. The aggrega-tes are extracted from 6 aggregate silos and weighed via a travelling aggregate weigher. The colour plants, which are arranged at the end of the silo battery, weigh the dry colour in each case and pass it to the aggregate weigh batcher. Each colour plant is equipped with 4 colour silos. The aggregate silos are in-stalled at ground level so they can be filled via wheel loaders or directly from the HGV. This arrangement also protects the aggregate from direct sun radiation and thus excessive heat. During the sum-mer months, the temperature can rise to above 50°C. A travelling transverse skip takes the weighed aggregates to the mixer elevators. The mixer for the core concrete has a capacity of 3,000/2,000 litres while for the face concrete mixer, a capacity of 500/330 litres has been en-visaged. Frima uses planetary motion mixers for the mixing plants. The core con-crete mixer produces 2 m3of compacted
concrete per mix and was deliberately chosen to be sufficiently large to meet the concrete requirements for hollow and solid block production with short cycle times. If necessary, additives weighed on 2 weighers in each case can be added to the mix. The cement is stored in three 60 m3 cement silos, one of which holds the white cement. There are also new, fully electronic, water meters which are fully resistant to water contamination. Water batching can either be adjusted manually or controlled using moisture measurement via microwave sensors.
The complete mixing plants are installed in the open air outside the production hall. This reduces the dust from the concrete block machines. The mixing plant can also be used for the production of other con-cretes such as ready-mixed concrete. Each of the concrete block machines is supplied with concrete from a skip con-veyor. Using two separate skips (one for the core concrete and one for the face
Assignment in the United Arab Emirates
ꔴ
CONCRETE PRODUCTS / CAST STONE
Friesische Maschinenbau GmbH & Co. KG, 26723 Emden, Germany
A Frima twin system has been in operation at Fujairah Building Industries in the United Arab Emirates for the last six months.
Normal production began after the completion of the installation and commissioning phase which lasted just two months. The products are
predo-minantly coloured paving stones with face con-crete and hollow blocks. The Frima twin system consists of two identical HP1200 Frima plants which are installed as a mirror image of each other – the block makers being arranged in the centre and the two rack systems arranged on the outside in each case.
Production hall of Fujairah Building Industries Layout – drawing of Frima twin system Frima mixing plant
concrete) prevents the core concrete from contaminating the face concrete, which is unavoidable when using a skip conveyor with just one skip.
Frima chose a Siemens programmable logic controller (PLC) to control the mixing plant. At the heart of the controller is a CPU with fail-safe technology and a visualisation system which also carries out batch logging and consumption analyses as well as having the usual recipe creation and management features. The plant can be operated either via the screen or via a mobile con-trol station (optional). The graphics display on the user interface displays the process on the screen with enough detail and clarity for all the processes on the mixing plant to be monitored con-stantly.
To minimise downtimes and cabling, the plant has been con-sistently decentralised. All drive controllers, evaluation modules for the highly accurate signals from the weighers and other modu-les for actuating the valves are located in the direct vicinity of the plant components.
왘
CONCRETE PRODUCTS / CAST STONE
Skip conveyor for supplying the concrete
Elevators for core concrete and face concrete
ICCX Sun City 19–21.02.2008
Booth No. 44 03b-Waren_110-137_en 19.11.2007 14:22 Uhr Seite 135
All mobile components such as the batch weighers or skip conveyors are fitted with frequency controllers and are dynamical-ly controlled according to weight in order to facilitate the shortest possible mixing times with optimised speed management. The automated silo transfer is also sup-plied as standard as is the dynamic batch-ing of all the aggregates, the target and actual values being compared according to each batch. The batching times and afterruns are then adjusted according to need.
Both Frima HP1200 machines are de-signed to handle 1,400 x 1,200 mm pal-lets. The production pallets consist of 50 mm thick plastic board. All core-concrete filler cars on Frima machines are fitted with hydraulically driven shaking grates. The mould boxes can therefore be filled thoroughly and quickly – particularly in the production of hollow blocks. The core-concrete and face-core-concrete filling machi-nes are independent components equip-ped with their own frame and 4 column
guides. Stresses on the main frame are therefore largely prevented. Electrically driven spindle drives are used to adjust the weighing platforms to the height of the mould. The filler cars are guided on rails inside the machine and rails above the car wheels prevent the cars from jumping during rapid filling processes. Pneuma-tically operated scrapers on both ends of the filler cars ensure that the moulds are thoroughly and uniformly filled.
The Frima vibrating table is fitted with 4 vibrators, 2 of which are used for prelimi-nary vibration and 2 for the main vibra-tion phase. The drive motors are mounted on separate crossbars outside the vibra-ting table and are connected via interme-diate shafts with flexible couplings to the vibrator units. This arrangement improves the stability of the motors by protecting them from the vibration. It also makes the maintenance work considerably easier than working on motors mounted directly on the vibrating table. The vibrator motors are regulated via frequency converters and the imbalance is adjusted manually.
The mould is braced pneumatically in the machine while the top of the mould is bra-ced hydraulically with the applied load. This provides the optimum clamping and makes it easy to change the mould – with-out any tools. The applied load on the machine is guided in 4 stable columns via long bushes and lifted and lowered by means of 2 hydraulic rams. When de-moulding tall products, the hydraulic brake can be used to hold the compacti-on head in the correct positicompacti-on. Two top vibrators integrated in the applied load make it easier to de-mould tall products while improving the block surface in paving stone production.
The production pallets with the fresh pro-ducts are taken to the elevator by means of a hydraulically operated slide. Here, Fujairah Building Industries have chosen 14-shelf double-stack with a 400 mm in-tershelf distance and 15 tonnes load limit. This means that it is possible to manufac-ture products up to 200 mm high over the full width of the production pallet. Having a capacity of 28 production pallets
redu-CONCRETE PRODUCTS / CAST STONE
Frima HP 1200 concrete block machine with pallet size 1,400 x 1,200 mm
Frima HP 1200 concrete block machine for paving stone produc-tion
ces the waiting times on the machine when the elevator is loaded and when simple products are being produced in rapid succession. There is hence no need for a collector in front of the lowerator. The load limit of 15 tonnes allows the pro-duction pallets to be fully loaded, even with heavy products. Together with the large core-concrete mixer, this is an excel-lent layout for the high-output production of hollow blocks.
A finger car transports the production pal-lets with the fresh products to one of the 16 chambers. Each of the chambers can take 280 pallets, which means that there is room for 4,200 pallets plus an empty chamber. The rack system at Fujairah Building Industries was supplied fully gal-vanised. The rack system is housed toget-her with the elevator, the finger car, and the lowerator in a separate section of the hall, separated by walls from the actual production area. The production pallets are supplied to the elevator or lowerator through a simple sluice. By arranging the rack system in a separate room, it is sur-rounded by a very damp atmosphere which promotes high strengths and short curing times. With this arrangement, there is no need for a circulation plant, roller shutter doors or chamber insulation. Fujairah Building Industries has acquired experience with this arrangement from its previous plants and is putting it to use with the Frima systems. Any maintenance work needed on the finger car can be carried out in a garage at the end of the rail system of the bogie. This section can be separated by a roller shutter door and the work carried out in a normal atmosphere. Like the wet end, the dry end of the Frima system is a hydraulically operated slide. A block release unit located before the packaging unit releases the products from all four sides. The packaging unit is powered electrically and hydraulically. The moving, lifting, lowering and turning actions are powered electrically while clamping the products from all four sides is performed hydraulically. The electric drives for moving and lifting/lowering are modern toothed-belt drives in omega design. The processes are therefore fast and quiet. The packaging unit transfers two or three layers of blocks to the slat conveyor in one movement. The main and side clamps are mechanically
synchroni-sed and can be actuated separately. It is possible to transfer simple, stable layers with just 2 side clamps.
The block packages placed on the slat conveyor are strapped horizontally and vertically. The empty pallets are cleaned with rotary wire brushes and then turned with a cross turner. An electrically actua-ted detent transport system guides the pal-lets to a collector in front of the machine.
The circuit is therefore closed.
The hydraulic system for the entire plant has been set up on a large platform above the control room. The connections to the machine and to the packaging unit are therefore short. The hydraulic unit is fit-ted with power-regulafit-ted axial cylinder pumps and a hydraulic accumulator which can release higher volumes of hydraulic fluid at short notice. Cooling is provided by a large oil-air cooler, additio-nal series-connected oil-water coolers are only used during very hot months. One conspicuous feature of the system is that all the valves are mounted as close to the consumers as possible. This provides the optimum control and the amount of pipe-work necessary is minimised. All the im-portant hydraulic processes in the system are regulated by proportional valves. Soft starting, high speed and soft braking can be adjusted via the controller to provide the optimum production conditions with short cycle times and low wear.
The controller for the mixing and metering plant as well as the block production plant is housed centrally in the control booth. The required switch cabinets are located above the booth on the platform in an air-conditioned room. As with the other mix-ing plant, the controller for the block pro-duction plant is based on the Simatic S7 series from Siemens with fail-safe techno-logy. Here also, the plant is consistently decentralised which means that there are other control panels and distribution units in the system which contain other periphe-ral equipment as well as the controls for manual operation etc.
Distance measurement of slides and machine sequences is achieved via linear encoders, which is a significant improve-ment on the rotary encoders previous used. The operation of linear encoders is fully contactless, i.e. there is no need for a
CONCRETE PRODUCTS / CAST STONE
REBAcolor
Betonflüssigfarben /
Liquid Concrete Colours
COLORin VS
Betonverdicker für Betonwaren /
Thickener for Dry- Cast Concrete
W/Z = 0,35 - 0,4 Weniger Sekundär-ausblühungen
Kein Verdursten, auch bei hohen Temperaturen
mechanical connection via a toothed belt and/or coupling. Frima uses an accuracy of 1/10 mm.
The electric drives are predominantly regulated via frequency converters. As with the hydraulic drives, the adjustment of acceleration, rapid movement and braking behaviour of the electric drives
can be optimised. The new-generation fre-quency converters which are used have excellent control and regulation charac-teristics and repeatability accuracy. System operation can be programmed, adjusted and monitored via a graphical, three-dimensional visualisation system.
System faults are signalled in plain text. All the adjustments can be entered via the keyboard and stored as product-specific recipes. By invoking 2 recipes on the screen simultaneously, it is easier to com-pare similar recipes and optimise the sequences. Since both the block plant controller with visualisation and the mixer controller with visualisation were
develo-CONCRETE PRODUCTS / CAST STONE
Frima packaging unit when transferring hollow blocks Frima packaging unit
CONCRETE PRODUCTS / CAST STONE
ped by Frima, the two systems are very similar and have the same logic. Thus, per-sonnel can understand and operate all processes easily.
A state-of-the-art teleservice module is available for servicing, maintenance or software updates. The service technicians in the production plant at Emden have direct access to all the control and visuali-sation systems via the telephone network or GPS/GPRS. Remote diagnosis up to sensor level (e.g. load cells and limit swit-ches etc.) is also possible.
Frima is relying on the consistent use of equal design parts. This reduces spare-parts warehousing and increases the availability of the plant. The hydraulic cylinders have the same diameter and the-refore the same seals; shafts and bearings are of the same design. Wherever possi-ble, wearing plates can be rotated, clamps for block-release units and pack-aging units are of the same design and electrical and hydraulic components are standardised as far as possible.
Far in excess of 50% of the production capacity of Fujairah Building Industries is covered by the two Frima plants. Both plants are versatile in use and supply first-class products in large numbers. If neces-sary, when used together, the plants can produce up to 120,000 hollow blocks
(40 x 20 x 20 cm) or 12,000 m2pavers with face concrete per day.
The successful cooperation with Fujairah Building Industries has another positive effect on Frima – new plants are being built in Russia, the Ukraine, Morocco, Egypt, Oman and other Arab Emirates.
쐽
Further information:
Friesische Maschinenbau GmbH & Co. KG Stedinger Str. 12 26723 Emden, GERMANY T +49 4921 5840 F +49 4921 584128 [email protected] www.frima-emden.de 15 hollow blocks 40 x 20 x 20 cm per pallet
CONCRETE MACHINERY AND MOULDS
Runnenbergweg 11, 8171 MC Vaassen, The Netherlands Tel: 0049-7842-994411, Website-Fax: 001-702-995-9981
www.humarbo.com
• SEMI- OR FULLY AUTOMATICMANUFACTURING LINES FOR SEMI-DRY CONCRETE PRODUCTS
• MOULDS FOR DRY- AND WET-CAST PREFAB CONCRETE
