Failure analysis of plastic extruder

Plastic extruder is a kind of common plastic machinery and equipment. In the process of daily operation of extruder, it is inevitable that various failures will occur in the extruder, which will affect the normal production of plastic machinery. The failure is analyzed in detail.

Host current is unstable

1. Reasons for production:

(1) Uneven feeding.

(2) The main motor bearing is damaged or poorly lubricated.

(3) A certain section of the heater fails and does not heat.

(4) The screw adjustment pad is wrong, or the phase is wrong, and the components interfere.

2. Treatment method:

(1) Check the feeder and troubleshoot.

(2) Overhaul the main motor and replace the bearings if necessary.

(3) Check whether the heaters are working normally, and replace the heaters if necessary.

(4) Check the adjustment pad and pull out the screw to check if there is any interference in the screw.

The main motor cannot start

1. Reasons:

(1) There is an error in the driving procedure.

(2) There is a problem with the main motor thread, and whether the fuse is burned.

(3) The interlocking device related to the main motor works

2. Treatment method:

(1) Check the procedures and restart the car in the correct driving sequence.

(2) Check the main motor circuit.

(3) Check whether the lubricating oil pump is started, and check the status of the interlocking device related to the main motor.

The oil pump does not turn on, and the motor cannot

(1) Check whether the emergency button is reset.

(2) The inverter has not discharged the induction current, turn off the main power supply and wait for 5 minutes before starting.

The machine head is not smooth or blocked

1. Reasons:

(1) A certain section of the heater does not work, and the material is poorly plasticized.

(2) The operating temperature is set too low, or the molecular weight distribution of the plastic is wide and unstable.

(3) There may be foreign objects that are not easy to melt.

2. Treatment method:

(1) Check the heater and replace if necessary.

(2) Verify the set temperature of each section, negotiate with the technician if necessary, and increase the temperature set value

(3) Clean and check the extrusion system and the machine head.

The main starting current is too high

1. Reasons:

(1) The heating time is insufficient and the torque is large.

(2) A certain section of the heater does not work.

2. Treatment method:

(1) When driving, use the hand wheel, if it is not easy, extend the heating time or check whether the heaters of each section are working normally.

The main motor makes an abnormal sound

 1. Reasons:

(1) The main motor bearing is damaged.

(2) A certain SCR in the SCR rectifier circuit of the main motor is damaged.

 2. Treatment method:

(1) Replace the main motor bearing.

(2) Check the thyristor rectifier circuit, and replace the thyristor component if necessary.

The main motor bearing temperature rise is too high

1. Reasons:

(1) Poor bearing lubrication.

(2) The bearing is seriously worn.

2. Cause:

(1) Check and add lubricant. Check the motor bearings and replace if necessary.

Unsteady head pressure

1. Reasons:

(1) The rotation speed of the main motor is uneven.

(2) The speed of the feeding motor is uneven and the feeding amount fluctuates.

2. Treatment method:

(1) Check the main motor control system and bearings.

(2) Check the feeding system motor and control system.

Low lubricating oil pressure

1. Reasons:

(1) The pressure setting value of the pressure regulating valve of the lubricating oil system is too low.

(2) The oil pump is faulty or the oil suction pipe is blocked.

2. Treatment method:

(1) Check and adjust the pressure regulating valve of the lubricating oil system.

(2) Check the oil pump and oil suction pipe.

The automatic screen changer is slow or not working

1. Reasons:

(1) Low air pressure or oil pressure.

(2) Cylinder (or hydraulic station) leaks (or leaks oil)

2. Treatment method:

(1) Check the power system of the screen changer.

(2) Check the sealing condition of the cylinder or hydraulic cylinder.

Safety pin or safety key is cut off

1. Reasons:

(1) Excessive torque of the extrusion system

(2) The main motor and the input bearing are not connected

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