The Sandvikdouble belt system

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Sandvik steel belts around the world

Sandvik steel belt technology forms thebasis for all of our double belt systemsand delivers a range of proven benefits.

• Hard and smooth surface

• Temperature resistant

• Corrosion resistant

• Easy to clean

• Endless weldable

• Wear resistant

• High thermal conductivity

• High tensile stress resistance

• Easy to repair

• Recyclable, because the steel belt can be remelted

Practically all Sandvik standard steel beltsare suitable for double belt processingapplications, and we can incorporate afull range of special designs to satisfyparticular requirements.

• Various grades of stainless or carbon steel

• Polished or plated surfaces

• Side retainer and retaining strips

• Perforations

• Longitudinal welding (for belt widths > 1.5 m)

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Our extensive experience of steel belttechnology, and the thousands of singlebelt systems we have built and installedfor processes in the chemical and foodindustries, has resulted in thedevelopment of the Sandvik double beltsystem. In developing this system, wehave combined all the advantages of thesteel belt with a full range of highlyefficient and advanced processingtechnologies.

The use of multiple roller sets provides a linear pressure across the belt width and a tumbling effect to the product tobe treated. Constant pressure can beapplied over a specific area and sets of rollers can be used to achieve acalibrating effect. The fact that

heating/cooling and pressurisingelements are modular means thatvirtually any profile can be achieved inone double belt system. These profilescan easily be adapted or optimisedaccording to particular processrequirements; the process can even bemodified by changing modules.

Other key advantages ofthe Sandvik double beltsystem include:• Heat treatment or cooling is applied

to both sides of the product formaximum efficiency

• Practically all common sources can beused for heating and cooling

• No contact between the product andambient air

• Vapours and fumes are reduced andkept away from the operating area

• Products which tend to curl awayfrom a single belt unit (resulting in irregular contact and loss of capacity)can now be handled

• Most feeding devices used for singlebelt coolers can also be used for double belt systems

Sandvik double belt systems – solutionstailored to your processing requirements

Double belt cooler for continuous production of silicon

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Maximum versatility for Feeding devices

Heating/Tempering

by convection

• water

• air

• roller chain

by radiation

• IR-radiation

Heating of upper and/orlower steel-belt

Heating with circulating air

Design data:

Belt width: standard 400 - 1.500 mmspecial design up to 4.000 mm

Belt temperature: max. 300 °C

Drive of upper andlower belt: electronic synchronisation

Belt guiding: automatic system or bonded V-ropes

Belt tensioning: automatic

Overflow weir feeder

Casting box

Casting box with rotary screen feeder

Turning table with product strainers

Extruder or feeding hose

Double roller feeder

Continuous feed of web or pieces

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optimum performance

Cooling

line pressure max 16,000 N/m (higher on request)

by convection

• water

• brine

• air

• roller chain

Cooling of upper and/orlower steel-belt

Cooling with circulating water

with roller chain (heating and pressing)

Pressing

finished product

with fixed rollers with sliding shoe

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Suitable for wide range of applications

A comprehensive range of feeding,heating, cooling and pressing elementsenables us to satisfy the particularrequirements of virtually any applicationor process.The panel to the left highlightsjust a few of the applications for whichwe have provided efficient, cost effectivesolutions.

Industry sectors for which this type ofdouble belt process offers significantpotential benefits include:

• Plastics (semi products)

• Automotive

• Construction/housebuilding (internal/external claddings)

• Insulation (heat, acoustic)

• Furniture

• Flooring

Element:Support rollers with spray nozzles for brine, cold or hot water.

Element:Support rollers with nozzles for hot or cold air.

Typical elements mounted into the base of a Sandvik double belt cooler

Process Typical application Characteristics

Granulation Flaking of resin • solidification through cooling fromboth sides (water cooling)multi-zone cooling if required

Film casting Membrane filter foil • reaction (exotherm)• tempering and drying• cooling

Sheet casting Artificial marble • controlled reaction with heating, calibration

• cooling

Sheet moulding GMT • heating and calibration• cooling

Lamination Sandwich-production • heating, melting of surface• bonding, cooling

Heating of • for subsequent moulding

Pure PE/PP/PA-sheets

Insulation material

thermoplasticsheets

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Double belt system for resingranulation

Versatile, efficient flaking of resinsSimultaneous cooling of the upper andlower belt results in highly efficientperformance. Furthermore, as sometypes of resin tend to curl away from asingle belt unit (resulting in irregularcooling and loss of capacity), the doublebelt system can be used to handle theseproducts more efficiently.

Finger breaker

Water collecting tank

FilterProduct pump Suction pumpCasting box

Melt

Double belt cooler

Cooling water

Chiller

Bagging

Chiller

Cooling zone

Process: cooling, solidification, granulation

Feeding: casting box

Cooling: chilled water, upper and lower belt

Pressure: very low, only by weight of upper belt

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Double belt system for sheet moulding

The double belt system provides the ideal solution for continuous productionof glass fiber reinforced plastics (GRP).Glass fiber mats and plastic (PE/PP) arefed into the double belt system and,through the application of heat andpressure, the glass fiber is impregnatedwith plastics.The product is then pressed, calibrated and cooled down under pressure.

Another key advantage is that the hard,smooth surface of the steel belt results inan excellent product surface quality;subsequent treatment of materials is unnecessary.

This system is widely employed in themanufacture of products used by theautomotive, construction and electronicsindustries.

Double belt press for glass fiber reinforced plastics

Delivering targeted heat and pressure

Process: heating, pressing and calibrating with heating platens cooling and pressing with cooling platens

Feeding: extruder

Heating: heated platens with roller chain

Cooling: cooled platens with roller chain

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Production plant for plasticsfiber compound materials

Sheet-moulding: reinforced plastics

We deliver complete installationsfor the continuous production offiber reinforced and homogeneousplastics, the base materials used toform parts for the automotive,building and machine industries.

Filmun-winder

Polymerisation Curing Cooling Filmre-winder

Cutting

Base material

Hot water and/or hot air Hot air Cold air and/or

cold water

Tem

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ProductPeak exotherm

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Sheet casting – Production of engineered stone

Double belt system forsheet casting

A typical sheet casting application is theproduction of artificial marble, in whichthe fluid compound – MMA fluid(methylmethacrylate), chips and filler – is combined in a batch mixer, degassed,then fed onto the lay down zone of thedouble belt casting unit.

When drawn into the machine, theproduct, still in liquid form, is thickness-calibrated in the nip zone, which consistsof a set of calibration rollers for theupper and lower belt.

The final calibration and solidificationprocess takes place in the polymerisationzone, where the product is tempered bywater sprayed against the ‘non product’sides of the upper and lower belts. Finalcuring is completed before the product iscooled down to the specified dischargetemperature.

Process: reaction (with heating andconsolidation), cooling

Feeding: casting box

Heating: hot air or water on lower belthot air or water on upper belt

Cooling: water and/or air onupper or lower belt

Complete systems from feed to finished product

With more than 250 double beltsystems installed worldwide (plusa huge number of single belt sy-stems),we have the experienceand technology to deliver complete system solutions fromfeeding to finished product.

Sheet-casting:artificial marble

Sheet-casting:Insulation material

Double belt system manufactured at our workshop in Fellbach/Germany.

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By using individual modules for productfeeding, heating, cooling, pressing and calibrating, each plant can easily be adapted to the different processing requirements of various applications.

Pilot plants are available in our test centers, where we can demonstrate ourprocesses and enable you to assess themin production conditions – using yourown products.

From simple feasibility tests to full-scaleproduction data, we can provide the levelof service you need, either from our democenters or on mobile plants installed at your own production facility.

If required, we can assume responsibilityfor everything from initial consultation,pilot testing, planning and design, throughengineering and installation to find commissioning and servicing.

A typical example of the recently developed double belt press for low pressure applications for the production of fibre compound

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www.smt.sandvik.com/sps

Sandvik steel belt technology – multiple processes in a single unit