What problems will PVC plates formed by gusset mold encounter?

1.Large longitudinal thickness deviation of PVC plate

①The temperature control of the barrel is unstable,which makes the melt flow unstable.The barrel temperature should be adjusted to make it stable.②The screw speed is unstable,resulting in unstable extrusion.The process parameters of the extruder should be adjusted to stabilize the extrusion.③The rotation speed of the roller in the third roller calender is unstable.The rotation speed of the three roller calender should be adjusted.④The traction speed is unstable,fast and slow.The traction speed should be adjusted to make it run smoothly.

2.Uneven horizontal thickness of PVC plate

①The design of forming mold is unreasonable,and the cross-sectional fabric flow is uneven.Modify the mold to make the die discharge evenly.②The gap adjustment of die lip is unreasonable and the gap is uneven.The middle clearance should be slightly smaller than the clearance on both sides.③The three roll gap deviation of the three roll calender is large,and the gap between the three rolls should be uniform.④The height selection and processing of three rollers are unreasonable.The middle height of the roll surface should be changed appropriately.

3.The surface of PVC plate is rough and Matt

①The working surface of three rollers is rough or sticky.The three roll working surface shall be cleaned and polished to make its surface smooth.②The calender roll temperature is low,so the three roll temperature should be appropriately increased.③.if the surface of the die lip is not smooth,clean the die lip.④If the filter screen is broken,replace it with a new one.

4.There are transverse lines on the surface of the plate

①.uneven mixing of materials causes fluctuation of extrusion volume.The materials mixed evenly should be replaced,and the process parameters of the extruder should be adjusted to make the materials plasticized well and the extrusion volume uniform.②The barrel temperature fluctuates greatly.Check and adjust the barrel temperature control system to ensure the temperature control accuracy.③The rotation speed of the three rollers is unstable or the roller surface is scratched.The rotation speed of the three rollers should be adjusted to make it run smoothly;Replace the injured roller or repair the roller surface.④The traction speed is unstable or the traction roller has insufficient tightening force.The traction speed and the tightening force of the traction roller should be adjusted to make the plate traction stable.

5.There are longitudinal lines on the surface of the plate

①The filter screen is broken.The filter screen should be replaced with a new one.②There are scratches on the lip surface of the die.The die lip should be repaired or replaced.③There are foreign matters or decomposition materials in the mold.The mold shall be cleaned to remove foreign matters or decomposition materials.

6.Plate fracture

①The extrusion temperature is low,and the melt plasticization is poor.The temperature of the fuselage and nose should be appropriately increased.②The gap opening of die lip is too small.It should be increased appropriately.The opening of the die lip is generally equal to or slightly less than the thickness of the plate.It expands after extrusion and is stretched to the required thickness.③Traction speed is too fast.It should be slowed down appropriately.The traction speed should be slightly faster than the extrusion speed.

7.Warping and unevenness

①The calender roll temperature is improperly controlled,especially the middle and lower roll temperature is too low.The roll temperature should be controlled within an appropriate range.

②The contact surface between the two ends of the plate and the air is too large,the cooling speed is too fast,and the cooling speed at the thinner part of the plate is also faster.When forming,the plate bends to the part cooled first,resulting in internal stress.In order to reduce the internal stress of forming,it should be cooled as evenly as possible to reduce drafting.

8.Bubble

①The raw materials are wet and the moisture content exceeds the standard.Keep the material low in moisture.②The temperature of the fuselage and nose is high,causing material decomposition.The processing temperature should be appropriately reduced.

9.Black or discolored stripes and spots on the surface

①The temperature of the machine head is too high,and the materials are overheated and decomposed.The temperature of the machine head should be reduced appropriately.②There are dead corners in the machine head,and the stagnant materials are decomposed.Clean the machine head to eliminate dead corners.③There are impurities blocking in the machine head,resulting in the decomposition of stagnant materials.Clean the machine head and remove impurities.④There is precipitate adhesion on the roller surface of the three roller calender.The surface of the roller shall be cleaned to remove the volatiles on the roller surface.

10.Surface spot

①The temperature of the lower roll of the three roller calender is high,and the plate adheres to the surface of the roller.The temperature of the lower roll should be properly reduced.②The liquid auxiliary precipitates on the surface of the third roller calender make the sheet adhere to the surface of the roller,and the roller surface should be cleaned.

11.Surface cold spot

①The roller temperature of the third roller calender is too low.The roller temperature should be appropriately increased.②There are wax precipitates adhering to the surface of the roller of the three roller calender.The roll surface should be cleaned.

Keyword:gusset mold

Article source:http://www.wx-mould.cn/