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Changshu smoothly da plastic products factory about the four major factors influencing the extrusion molding
by：CSSSLD
2021-01-23
Extrusion forming is a plastic material and main technology of plastic pipe production mainly through extrusion mechanism of the plastic material and plastic pipe material, changshu well below da plastic products factory to talk about the four major factors influencing the extrusion molding!
1. Temperature
temperature is one of the important conditions for the extrusion molding smoothly.
from powder or granular solid material, high temperature products from the nose, has experienced a complex process of temperature changes. Strictly speaking, should refer to the plastic melt temperature, extrusion molding temperature but the temperature depends largely on the temperature of the cylinder and the screw, a small part from the mixture in the cylinder when the friction heat, so often to approximate molding temperature materials barrel temperature. Since the cylinder and plastic temperature in screw paragraphs have differences, in order to make the plastic conveyor in the cylinder, melting, homogenization and extrusion process smoothly, in order to efficiently produce high quality product, the key problem is to control the temperature of the cylinder paragraphs, material is to rely on the regulation of extruder barrel temperature heating cooling system and temperature control system. The nose temperature must be controlled under plastic pyrolysis temperature, comparable to the nose and mouth mold temperature slightly lower, but should guarantee the plastic melt with good liquidity.
in addition, in the process of forming temperature fluctuations and temperature difference, will make the plastic parts produced uneven residual stress, the strength of each point and surface defects such as matt grey. The fluctuations and temperature difference can be caused by many factors, such as heating, cooling system is not stable, the screw rotation speed change and so on, but with screw design and selection of good or bad.
2. Pressure
in the process of extrusion, due to the resistance of the material flow, the change of the screw groove depth, and the filter, filter plate and the mouth mould produced, such as, and along the axis of the cylinder, has certain pressure inside the plastic. This pressure is plastic into dense homogeneous melt and plastic pieces of one of the important conditions.
add head pressure can improve the mixing uniformity and stability of the melt extrusion, improve product density, but head pressure will affect production.
as well as temperature, pressure changes over time will also cause a periodic wave, the wave also has adverse effect on the quality of plastic parts, the change of screw speed, heating and cooling system of instability are causes of pressure fluctuations. In order to reduce the pressure fluctuations, should be reasonable control the screw rotation speed and control precision of temperature of heating and cooling device.
3. Extrusion rate
extrusion rate ( Also called extrusion speed) Is the unit of time extruder die extrusion plastic quality ( The unit is kg/h) Or length ( The unit is m/min) 。 The size of the extrusion speed characterization of the extrusion production capacity.
a lot of factors influencing the extrusion speed, such as the nose, the structure of screw and cylinder, screw speed, heating and cooling system structure and the characteristics of plastic, etc. Theory and practice have proved that extrusion rate with screw diameter, screw groove depth, length and the screw rotation speed increases, with the screw at the end of the melt pressure and the screw with a nitrogen-treated barrel clearance increases. In the structure of extrusion machine and plastic and plastic types have been identified, extrusion rate is only related to the screw rotation speed, therefore, adjust the screw rotation speed is to control the rate of the main measures.
extrusion rate also exists a wave phenomenon in the process of production, this will affect the plastic parts geometry and dimensional accuracy. Therefore, in addition to the correct screw structure and size parameters, also should strictly control the screw rotation speed, strictly control the extrusion temperature, prevent extrusion pressure and the melt viscosity caused by temperature change and change, leading to speed fluctuations.
4. Traction speed
extrusion molding parts, mainly in the production of continuous traction device must be set so. Extrusion of plastic pieces from the nose and mouth mould, will happen under the action of the traction stretch orientation. Stretch orientation degree is higher, the plastic parts along the direction of the orientation of the tensile strength is, the greater the but after cooling length contraction is also big. Usually, the traction speed and extrusion speed. Traction speed ratio according to drawing and extrusion speed ratio, its value must be greater than 1.
1. Temperature
temperature is one of the important conditions for the extrusion molding smoothly.
from powder or granular solid material, high temperature products from the nose, has experienced a complex process of temperature changes. Strictly speaking, should refer to the plastic melt temperature, extrusion molding temperature but the temperature depends largely on the temperature of the cylinder and the screw, a small part from the mixture in the cylinder when the friction heat, so often to approximate molding temperature materials barrel temperature. Since the cylinder and plastic temperature in screw paragraphs have differences, in order to make the plastic conveyor in the cylinder, melting, homogenization and extrusion process smoothly, in order to efficiently produce high quality product, the key problem is to control the temperature of the cylinder paragraphs, material is to rely on the regulation of extruder barrel temperature heating cooling system and temperature control system. The nose temperature must be controlled under plastic pyrolysis temperature, comparable to the nose and mouth mold temperature slightly lower, but should guarantee the plastic melt with good liquidity.
in addition, in the process of forming temperature fluctuations and temperature difference, will make the plastic parts produced uneven residual stress, the strength of each point and surface defects such as matt grey. The fluctuations and temperature difference can be caused by many factors, such as heating, cooling system is not stable, the screw rotation speed change and so on, but with screw design and selection of good or bad.
2. Pressure
in the process of extrusion, due to the resistance of the material flow, the change of the screw groove depth, and the filter, filter plate and the mouth mould produced, such as, and along the axis of the cylinder, has certain pressure inside the plastic. This pressure is plastic into dense homogeneous melt and plastic pieces of one of the important conditions.
add head pressure can improve the mixing uniformity and stability of the melt extrusion, improve product density, but head pressure will affect production.
as well as temperature, pressure changes over time will also cause a periodic wave, the wave also has adverse effect on the quality of plastic parts, the change of screw speed, heating and cooling system of instability are causes of pressure fluctuations. In order to reduce the pressure fluctuations, should be reasonable control the screw rotation speed and control precision of temperature of heating and cooling device.
3. Extrusion rate
extrusion rate ( Also called extrusion speed) Is the unit of time extruder die extrusion plastic quality ( The unit is kg/h) Or length ( The unit is m/min) 。 The size of the extrusion speed characterization of the extrusion production capacity.
a lot of factors influencing the extrusion speed, such as the nose, the structure of screw and cylinder, screw speed, heating and cooling system structure and the characteristics of plastic, etc. Theory and practice have proved that extrusion rate with screw diameter, screw groove depth, length and the screw rotation speed increases, with the screw at the end of the melt pressure and the screw with a nitrogen-treated barrel clearance increases. In the structure of extrusion machine and plastic and plastic types have been identified, extrusion rate is only related to the screw rotation speed, therefore, adjust the screw rotation speed is to control the rate of the main measures.
extrusion rate also exists a wave phenomenon in the process of production, this will affect the plastic parts geometry and dimensional accuracy. Therefore, in addition to the correct screw structure and size parameters, also should strictly control the screw rotation speed, strictly control the extrusion temperature, prevent extrusion pressure and the melt viscosity caused by temperature change and change, leading to speed fluctuations.
4. Traction speed
extrusion molding parts, mainly in the production of continuous traction device must be set so. Extrusion of plastic pieces from the nose and mouth mould, will happen under the action of the traction stretch orientation. Stretch orientation degree is higher, the plastic parts along the direction of the orientation of the tensile strength is, the greater the but after cooling length contraction is also big. Usually, the traction speed and extrusion speed. Traction speed ratio according to drawing and extrusion speed ratio, its value must be greater than 1.
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