3531 Precautions for sheet making machine - China Roll Forming Machine, Steel Water Tank Machine, Steel Silo Rollformer, Suppliers, Manufacturers, Factory - J&R
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Precautions for sheet making machine

2023-06-17
(1) The temperature of each section on the barrel of the plastic sheet production equipment gradually increases from the feeding section to the junction between the barrel and the forming mold.

(2) The temperature of the forming mold is slightly higher than the temperature of the barrel. Control the temperature above 5 to 10 ℃. The temperature at both ends of the mold is slightly higher than the temperature in the mold, and the higher temperature is controlled at 5-10 ℃.

(3) In the form of sheet feeding, the upper surface of the center roller of the three rollers should be on a horizontal plane with the lower surface of the mold lip; The end face of the lip is parallel to the centerline of the center roller, with a distance of 50-100mm.

(4) The gap between the mold lips should be slightly less than or equal to the thickness of the plate product, and the gap between the center of the mold lips should be slightly less than the gap between the end mold lips on both sides.

(5) Note that the roughness R of the three roll working surface should not be greater than 0 2pm. When tidying up the roller surface, it is not allowed to scratch it with a hard steel knife, but rather use a copper knife to tidy up the remaining material on the roller surface.

(6) The roller surface should have some medium height; The gap between the three rollers should be equal to or slightly greater than the thickness of the plate.

(7) The temperature control of the forming mold should be stable. When the temperature is high, the movement speed of the molten material in the mold becomes faster; When the temperature is low, the movement speed of the molten material in the mold slows down. Unstable melt flow rate can cause significant longitudinal thickness errors in plate (sheet) products.

(8) Pay attention to controlling the working surface temperature of the three rollers, which should be slightly higher for the inlet roller and slightly lower for the outlet roller. The high temperature of the roller surface makes it difficult for the slab to detach from the roller, and the surface of the product is prone to transverse lines; The temperature is low, and the appearance of the product is not shiny. According to this phenomenon, the temperature control of the roller surface needs to be adjusted in a timely manner.

(9) The working speed of the three rollers is slightly higher than the extrusion speed of the slab from the mold mouth, with a general speed difference of no more than 10%. The working speed of the three rollers should be controlled smoothly, and running speed that is too fast or too slow has a significant impact on the thickness error of the plate.

(10) When the polyolefin plastic is extruded to form the plate (sheet), the screw adopts a Mutant structure, the compression ratio is (3-4): 1, and the melt activity rate is: HDPE 0 3-2.0g/10min, LDPE 0.1-0.3g/1Omin, PP 0.5-1 5g/10min. ABS and other non crystalline high polymer resin extruded plates (sheets) should be made with gradient screws with a compression ratio of (1.6-2 5) : 1.

(11) The extrusion molding of plastic plates (sheets) requires dehumidification and drying treatment before extrusion, except for PVC, polyethylene, and polypropylene resins, which are generally not subjected to dehumidification treatment. Other plastics (such as ABS, polyamide, etc.) should be required to undergo dehumidification and drying treatment before extrusion. Otherwise, an exhaust type extruder should be used for extrusion molding.