PP/PE Sheet Production Line

ABS Sheet Production Line: It can produce ABS/HIPS/PP/PE/PC /PVC sheet and board, with dirrferent screw

LJC built its first wholly designed and in-house manufactured extruder in 1984The model was a D120( 120 screw diameter) 35:1 L/D liquid cooled extruder and had a throughput of 550 kg/h, using polypropylene material.The LJC extruder technology of today has been developed over the last twenty years; constant research coupled with rigorous testing programs has made LJC a world leader in the manufacture of precision extruders for mass production of high quality plastic sheet.The combination of both in-house testing and feedback of “in-service” machines has allowed LJC to develop extruders that both maximise machine efficiency and suit customer requirements. The original LJC extruders screw design for various materials ( PP-PS-PET-ABS-Multilayer) has been extensively tested and is constantly upgraded to fit the raw materials improvements, to achieve optimum quality and throughput.LJC EXTRUDERS can be supplied in a range from 45 mm to 150 mm, with air or water cooling system. The L/D ( length/diameter) ratio is from 30/1 to 35/1.The barrel supply collar has, on the inside, a cooling circuit at controlled temperature. Cooling of extruder cylinder in the water-cooled models is by an independent central unit, while cooling of extruder cylinder in the air-cooled models is by motor-ventilators for each single control zone. The number of control zones ranges from 4 to 7 according to the model and their temperature is controlled by a computerized LJC system.The screw thrust has an axial roll-bearing and abundantly dimensioned rolls.The connection between motor and  gear is direct, through an elastic joint, suitable for absorbing bumps and vibrations.The extruder barrel is made by two-metal alloy; in the smaller models (D45-D60-D80), is made by nitrided steel as standard, by two-metal alloy as optional.  The gear , the barrel and the motor are installed in a single structure, solidly made of electro-welded pieces. Special covers in stainless steel , easily removable, protect the heater cylinder zones.THE EXTRUDER MOTOR is AC or DC, complete with motor-ventilator. The extruder motor is placed under the barrel to reduce overall dimensions, while the motor drive, variable speed and constant torque, is included in the general control panel of the extruder. The venting plant is made up of: liquid ring, vacuum pump, flowmeter for pump protection. A water-reclaiming  system can be optionally supplied.THE HYDRAULIC SCREENCHANGER can be in two versions:

Single filtering systemDouble filtering system ( continuous filtering), without any flow interruption

There is also a separate hydraulic central unit for the filter plate exchange, which can be used to supply other extruders.All the extruders are equipped with a GEAR PUMP SYSTEMThe gear pump system includes a DC motor, a gear-box, a cardan joint and a control system on the general control panel.All the extruders can be supplied with various ACCESSORIES, such as :

Material pressure readout Material temperature readout Static mixer

The FLAT DIE can be supplied either for sheet or for plate production. The available die widths ranges from 700mm to 1700mm. The thickness varies from 0,2mm to 8 mm. All dies are made of two blocks by thermically treated steel. The upper lip is flexible, adjustable with bolts of differential thread, which permit micrometric adjustment. There is an inside flexible bar for flow adjusting. Adjustable deckles determine the sheet width.Before the flat die, a COEXTRUSION BLOCK can be inserted, to connect one or more extruders.

The LJC CALENDERS are divided into four basic models, identified by the rolls diameter:750-500-350-250 mm. The calender and the haul-off can be made in one only structure for 250 and 350 mm versions; or in 2-3 pieces ( calender-extra cooling roll-haul off) for the 500 and the 750 mm versions.The calender is made up of a base in thermowelded laminate and a frame of thickly bolted laminate .The main structure is made up of 3 cylinders  on a vertical axis:

1st Upper cylinder, calibrator and cooler, applied on mobile arms moved by pneumatic pistons 2nd Central cylinder, calibrator and cooler, applied on rigid arms 3rd Lower cylinder, calibrator and cooler, applied on mobile arms moved by pneumatic pistons

The cylinders are chromed and then mirror-polished ; before chroming  they are coated by 3mm.thick special material , with hardness of 52-54 HRC.  The cylinders have a special inside configuration for the cooling circuit, obtained through double-flow channels to achieve maximum uniformity on all the surface in contact with the plastic material.The inner cylinders cooling channels are obtained by extrusion technique ( not by calendering). Opening and closing of the cylinders is done by pneumatic pistons.Various easily accessible safety devices ensure the cylinders opening and the blocking of the motors in case of necessity.Cylinders movement is by one or more AC motors; the transmission between gearbox and cylinders is by modular gears, toothed belts and epicyclical  gearboxes.The haul-off , in the 500 and 750 mm models, has a separate structure, while in the smaller models it is integrated in the main calender structure. It is made up of two rolls positioned on a vertical axis: a lower motorized roll with chromed surface and an upper counter-roll, 200mm in diameter, with rubber covering , mounted on mobile arms moved by pneumatic pistons.The edge-trim system consists of 2 single structures, one to the right and the other to the left. Two side winders with expandable sectors (motorized) wind up the edge trim.The central thermoregulation unit of the calender cylinders is made up of 3-4 independent circuits. Each unit has its own closed circuit , consisting of an heat exchanger with heating chamber and a pump for the fluid circulation.WINDERS FOR REELSWinders for reels up to 2000 mm. diameter x 1200 mm width.Winders are equipped with a safety sheet storage, useful during the sheet cutting and re-starting phases.The motors are AC and controlled by an electronic drive with automatic sheet draw adjustment. The standard winder shafts are expandable, with a diameter from 70 to 200 mm.

ELECTRONIC CONTROL BOARD FOR EXTRUSION LINESuited to control and to easily adjust all the machine setting parameters.

PP/PE Sheet Production Line