The company Siberian Constructing Technologies designs and assembles automated lines for bulk and laminated foam polystyrene. When processing data of these production lines, key concept is performance level control, outputs parameter stability and also engineering of automation and quality control systems at all manufacturing stages.
Automation of manufacturing processes of bulk and laminated foam polystyrene production allows not just reduce product cost but also significantly raise stability of products' key properties. At the same time automation line minimizes human factor.
Raw materials used for foam polystyrene production must satisfy requirements of corresponding standards and regulations and also provide outputs of specified properties.
For foam polystyrene production, as critical raw materials foam (bead) polystyrene like Loyal Chemical Ind. Corp. (China), Xingda (China), BASF (Germany), LG, Samsung or their Russian equivalents is used. When manufacturing bulk and laminated foam polystyrene it is allowed using foam polystyrene granules obtained after crushing of polystyrene foam slabs waste. In this case volume of such granules should not exceed 10% by total mass of the finished product and also environmental and fire safety requirements must be observed. Bags with raw materials are unloaded with power truck and stored on the pallets. Storage time of each batch should not exceed three months after its delivery (according to certificate). Temperature of raw storage should be maintained within the limits of 10 to 15°С. As necessary, bags with polystyrene bead are unpacked and bead is fed to pre-foamer receiving hopper.
Foaming area includes: pre-foamer of cycle type, EPS granules dryer, pneumatic system and control unit. Bags with polystyrene bead are unpacked, and certain quantity of raw material is loaded into pre-foamer. Then pressurized steam is fed into the pre-foamer thermal chamber. Under the influence of steam primary foaming of bead polystyrene performs. Temperature in pre-foamer chamber must be in the range of 95 to 100°С. Steam pressure in the chamber is controlled with pressure reducing valve. When foamed granules obtained specified volume steam delivery stops and EPS granules start loading into the dryer. After drying foamed granules enter the ageing hoppers by pneumatic system.
In polystyrene foam production conditioning (ageing) of pre-foamed polystyrene granules is a compulsory stage. During ageing vacuum arisen inside granules (as a result of foaming) supports air infusion into polystyrene foam cells. Conditioning is performed in the ageing hoppers at comfort temperature 16- 25°С during 4 – 12 hours. Secondary or multiple (if necessary) foaming of polystyrene granules is performed in the same way as primary one. Number and volume of ageing hoppers should be estimated depending on line capacity.
EPS granules right after conditioning (ageing) are fed from the ageing hoppers to transfer bin with help of pneumatic system. The transfer bin is equipped with level sensor. Then specified quantity of granules goes from the transfer bin to the block-mold. The block-mold is a vessel with steam jacket and pressure cap. When granules are fed into the vessel, block-mold closes pressure tight. Steam is delivered into the block-mold vessel and granules are heat treated. As a result granules are expanded again and bake making polystyrene block.
Then molded block is cooled by discharging with the help of vacuum unit. Ready block is forced from the block-mold with pressurized air. To stabilize internal stress and to reduce moisture of ready block, before cutting it should be aged at normal conditions for 12 — 24 hours.
After ageing polystyrene foam block enters the cutting area. On combined cutting unit block is trimmed and further cut to get sheets of specified sizes. The unit allows classifying blocks in both horizontal and vertical planes. This unit operates automatically, manual control mode is additionally provided. There is electronic control of bars filament in the unit, and also variable speed control of cutter frames. Compound cutting has high accuracy because all operations take place without moving block.
Storage of polystyrene foam slabs must be performed according to p. 5.7 of GOST 15588-86. When making bags requirements of GOST 21929-76 and GOST 24510-80 must be complied.
Production residuals are crushed in the polystyrene foam crusher. Material is fed into square mesh in the top cover and goes to rotating hammers. During hammers rotation material breaks into separate granules. When breakage is over EPS granules enter the independent chamber, then by the draft fan they go to the pneumatic system and loaded into the separate collecting hopper. Crushed foam plastic is used again in production of polystyrene foam slabs, but in this case its volume should not be more than 10% of finished product total mass.