How to realise that the PVC foam board production line can produce 5-25mm thick wall panels and cabinet panels

The advantages of a single line for PVC foam board production with both thin wall panels (5mm) and thick cabinet panels (25mm) are tremendous. Many manufacturers assume such a wide thickness range would require different lines or extensive reconfiguring. All these are easily managed by us at JIANGSU XINHE INTELLIGENT EQUIPMENT CO., LTD. , with its foam board extrusion system. The following is a list of important technologies and techniques that enable this.

Twin screw extruder with adjustable compression ratio and screw design

The extruder really is the backbone of any foam board line. Board thicknesses from 5mm to 25mm can be produced by being able to process formulations that have a varying melt strength and blowing agent activity. At JIANGSU XINHE INTELLIGENT EQUIPMENT CO., LTD. ,we use a parallel twin-screw extruder with a specially designed screw profile. The screw configuration ensures homogeneous mixing and low met viscosity, guarantee smooth flow through narrow die gaps for thinner boards (5mm to 10mm). The screw design starts to change with thicker boards (up to 25mm) towards high melt strength with controlled cell structure. Our screw consists of adjustable compression sections and mixing elements which can be optimized for the thickness desired. This flexibility means that the same extruder can be used to consistently create foam cell morphology at 5mm, 10mm, 15mm, 20mm and 25mm.

Quick-change die system with adjustable lip opening and interchangeable inserts

The thickness profile of the board that is extruded is determined by the die. This is because a fixed die opening would not provide a cost-effective solution for manufacturing a thin wall as well as a thick cabinet panel. JIANGSU XINHE INTELLIGENT EQUIPMENT CO., LTD. designs foam board dies with adjustable lip mechanism and interchangeable die inserts. The opening of the lip can be mechanically opened between 3mm and 30mm. Servo lip adjustment systems can be included if needed for this precise control. The same type of die body is used. This fast changeover feature allows for changeover times of less than 30 minutes, versus hours.

Multi-stage vacuum calibration and cooling table with zone control

The foam board is then taken out of the die and goes through the calibration and cooling. When using thick boards, it is important that the cooling is controlled, to prevent internal voids and surface roughness. JIANGSU XINHE INTELLIGENT EQUIPMENT CO., LTD. has a long cooling table with independent temperature control zones. In the first zone, for 5mm wall panels, a good water-spray is used to quickly freeze the surface. It's a gentler process for the 25mm cabinet panels. Zones are then added, cooling increments get more intense, as the board gets stiffer. The vacuum pressure can be adjusted according to the thickness. The thinner the board, the less the vacuum must be to prevent crushing the foam structure. The thicker the boards, the more vacuum they require to be held at dimensions. This zoning technique will ensure flat surfaces, straight edges and uniform thickness in both thin and thick boards out of the table.

Hydraulic haul-off unit with adjustable roller gap and pressure

A standard haul-off unit, having a fixed distance between its rollers will not accept a 5mm board and a 25mm board at the same time. JIANGSU XINHE INTELLIGENT EQUIPMENT CO., LTD. , has the hydraulic haul-off unit with adjustable gap between rollers. The upper and lower rollers are adjusted with the minimum pressure between them for 5mm size to prevent the delicate surface of the foam. Servo-motors are used to accurately control the haul-off speed. Thin boards normally are run at higher speeds to maximize output, and thick boards are run at slower speeds to provide sufficient cooling. The system stores different thickness profiles, so that recipes can be quickly recalled.

PLC-based control system with thickness-specific parameter sets

The change from 5mm to 25mm production is a more complex process than mechanical changes alone. All the process parameters (temperature, screw speed, cooling intensity, haul-off speed and cutter timing) vary with the thickness. JIANGSU XINHE INTELLIGENT EQUIPMENT CO., LTD. has built in a PLC control system which has multiple product recipes. When an operator changes from 12mm wall panel to 20mm cabinet panel, the saved recipe is called up on the touch screen. The system automatically controls barrel temperatures, screws speed, die lip opening, cooling zone flow, haul-off speed, roller gap, and cutting length. This automation will eliminate guesswork and will reduce the scrap during changeovers.