The inner diameter of the nozzle are generally from import to export convergence, so closely contact with the mould.
Due to the inner diameter of the nozzle is not big, when the melt by velocity increases, the shear rate increases, can make the melt further plasticizing.
The structure of the nozzle is associated with the flow characteristics of plastic, the requirement of the nozzle is of simple structure, large resistance, absence of melt flow phenomenon.
Thermoplastic injection nozzle type many, the structure is different.
General type is a common form of the nozzle, the nozzle structure is simple, easy fabrication, no heating device, the injection pressure loss is small, often used in polyethylene, polystyrene and cellulose and plastic injection molding processing plants.
both plunger and shunt spindle is plunger type injection machine inside the cylinder of the main parts.
Plunger is a hard metal round bar, usually for 20 - its diameter
Can plunger reciprocating motion within the cylinder, its action is passed on the plastic pressure, make the melt injection into the mold.
Plunger type injection molding machine must use shunt spindle and moving screw injection molding machine of plasticizing effect is good, do not use shunt spindle.
shunt spindle is installed in front of the cylinder at the center of the part, is the metal cone tapered on both ends.
Shunt shunt rib of a few article highlights on the spindle, and cylinder wall immediately, positioning and the effect of heat transfer.
Shunt is the role of shuttle in the cylinder of the material flows through here into a thin layer, make plastic melt shunt and convergent flow, in order to shorten the heat stroke, both sped up the heat conduction, but also to reduce or avoid overheating plastic caused by thermal decomposition phenomenon.
plastic melt after shunting, in shunt spindle and cylinder clearance flow velocity increases, the shear rate increases, resulting in a larger frictional heat, high temperature, viscosity, make further plastic mixing plasticization, effectively improve the plunger type injection molding machine production efficiency and product quality.
Screw is an important part of a mobile screw injection molding machine, is a surface with a thread of the metal bar, its role is to plastic conveyor, compaction, plasticizer transfer molding pressure.
cylinder that is plasticizing chamber.
Its inner surface is smooth and streamlined, no crack and corner.
The volume of cylinder determines the amount of nominal injection molding machines.
The plunger cylinder volume for nominal injection quantity of 6 - often
Eight times, in order to make sure the plastic adequate residence time and contact heat transfer surface, good plasticizing.
Because of the plastic screw pushing and stirring effect, heat transfer and plasticizing efficiency is high, the mixing effect is good, so the capacity of the screw cylinder generally only nominal 2 - the amount of injection molding
Outer cylinder block heating device, through the control system to display and control the temperature.
From loading port to the direction of the nozzle, the temperature of the cylinder is increased.
length to diameter ratio of injection screw in 10 -
In 2-15, between compression ratio
Screw homogenization section length is shorter, but the spiral groove depth is deeper, in order to improve production efficiency.
In order to improve the quantity of plasticizing, charging period is longer, about half the length of the screw.
The screw head is pointed, and the nozzle can be a very good match.
Nozzle in the front of the cylinder is connected cylinder and the channel of injection moulds, its role is to lead the melt from the cylinder into the mold, and there is a certain range.
when the screw inside the cylinder rotates the plastic to get involved in the spiral groove inside the cylinder, and gradually to the compaction, the vent gas from material, plastic melting gradually.
Since then, the plasticizing uniform material continuously by the screw into the front end of the cylinder, and gradually accumulated near one end of the nozzle.
At the same time, the screw itself by the pressure of the melt and slowly back.
When the melt injection molding processing factory accumulated reaches a maximum injection quantity, screw stop running and back.
Screw transmission pressure, viscous flow melt injection into the mold.
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