Main process parameters of Wuhan Handern plate production

日期:2020/12/31 8:50:23 / 阅读: / 来源:本站

Main process parameters of Wuhan Handern plate production
(1) Extrusion temperature extrusion temperature should be based on raw materials, extruder characteristics, die type. Plate production line www.handern.com
The temperature of the die is about 5 ~ 10C higher than that of the fuselage. The temperature of the die is too low, and the surface of the plate is dull and easy to crack. If the die temperature is too high, the material will change color, decompose and have bubbles in the plate. The temperature of flat die is generally low in the middle and high on both sides. The melt temperature is an important factor affecting the fluidity of the die. In order to ensure that the resin is extruded from the die lip in an equal amount, the plate with uniform thickness can be obtained. In addition to the design and manufacture of the die, the resistance in the die cavity is uniform, and the temperature fluctuation at each point of the die should be carefully controlled,. Generally, it is allowed to fluctuate less than 5 C, which is the most basic condition for making plates with uniform thickness. In addition, the resistance bar in the die can be adjusted to control the resin flow speed, so as to realize the thickness uniformity of the plate.
(2) Three roller calender temperature and speed three roller is the plate cooling, calendering, fixed thickness equipment, its process conditions are straight
Press to affect the appearance of the sheet. In order to prevent the plate from sticking to the roll room, the molding benefit should be too high. In order to prevent the plate from bending due to internal stress, the plate should be cooled slowly, three rollers should be heated, and a temperature regulating device should be set. If the temperature of the roller is too high, it will be difficult for the plate and sheet to take off the roller, and the surface will produce transverse stripes. If the temperature of the roller is too low, the plate is not easy to cling to the surface of the roller, and the surface of the plate will produce spots and no luster. Polyolefin is a kind of product type plastic. It crystallizes when the roller temperature is low. The product is transparent and has small wrinkles. The roller temperature should be high enough to make the molten material completely close to the roller surface, otherwise the plate or sheet will have stripes. The temperature of the three rollers is related to the raw material, the thickness of the plate and the roll position.
When the die lip gap is fixed, the sheet thickness is controlled by the three roll speed, and the sheet drawing ratio should not be too large, which will cause the sheet unidirectional orientation, resulting in the improvement of longitudinal properties and the decrease of transverse properties. For the plate to be processed twice, the drawing ratio should not be too large, which will increase the longitudinal yield of the plate. The speed of three rollers is generally controlled to be 19 ~ 25% higher than that of extrusion.
When the plate needs to be embossed, the middle roller can be replaced by the engraving roller. In order to make the pattern clear, the temperature of the middle roller can be increased as appropriate. At the same time, the middle roll is replaced by heat-resistant nitrile rubber cots with hardness of 85 degrees, and the cooling water is used in the roll to avoid material sticking. Plate production line www.handern.com
(3) The thickness of the drawing roller is less than or equal to the thickness of the plate after extrusion. In addition to adjusting the die temperature, the die resistance block can also be adjusted to change the resistance in the width direction of the die, so as to change the flow rate and the thickness of the plate. The gap of die lip can be adjusted by micro adjustment of plate thickness; when the thickness adjustment range is large, the resistance adjustment block should be adjusted. In order to obtain uniform thickness, the gap between die lips should be adjusted to be smaller in the middle and larger on both sides. It is found that the distance between the three rollers of heat recovery is adjusted to be equal to or slightly greater than the thickness of the plate.
The polycarbonate sheet is in molten state during extrusion, so there should be a fixed amount of material storage between the two feeding rolls to prevent material shortage due to uneven die discharge. The stock quantity shall be based on the guarantee of no stripe on the plate.
(4) Traction speed the purpose of traction is to make the plate from the cooling roller out of continuous cooling, until cutting, has been maintained "tension" state. If there is no tension during cooling, the sheet will deform. If there is no tension during cutting, the cutting will be irregular. The traction tension is closely related to the sheet properties. If the tension is too large, the sheet will form cold drawing, and the sheet will produce internal stress, which will affect the service strength and secondary processing. If the tension is too small, because the plate has not been fully cooled and shaped, the plate will become uneven, or even have no use value. Plate production line www.handern.com

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