- The principle of bottle blowing machine
After the liquid plastic is sprayed out, the bottle blowing machine uses the wind force blown out by the machine to blow the plastic body to a certain shape of the mold cavity to make a product. This machine is called a bottle blowing machine.
Bottle blowing process: 1. The preform (embryo) is heated and softened by infrared high temperature irradiation. In order to maintain the shape of the bottle mouth, the preform (embryo) mouth does not need to be heated, so a certain cooling device is required to cool it; 2. This stage is to place the preheated bottle (embryo) into the blow mold that has been made, inflate it with high pressure, and blow the preform (embryo) into the required bottle.
Bottle blowing machine is a kind of hollow container made of plastic particles through blow molding process. At present, the more common models include hollow extrusion blow molding machine using PP and PE for one-time molding, injection stretch blow molding machine using PET, PC or PP for two-time molding, and newly developed multi-layer hollow extrusion blow molding and stretch blow molding.
Common faults and diagnostic methods of bottle blowing machines
Fault 1: Poor transparency of PET bottles
Reasons: 1. Heating temperature is too high 2. Heating time is too long 3. Compressed air contains moisture 4. The injection molded embryo tube itself is not transparent 5. The embryo tube design is not suitable 6. The inflation ratio is too small
Troubleshooting methods: 1. Cooling 2. Shortening heating time 3. Using a dryer to remove water 4. Improving embryo tube quality, selecting materials and increasing the dryness of raw materials 5. Improving embryo tube size design 6. Reducing embryo tube diameter
Fault 2: PET bottles have a pearly luster and whitening
Reasons: 1. Heating temperature is too low 2. The embryo tube wall thickness is uneven 3. The embryo tube thickness is too thick and the heating penetration is insufficient
Troubleshooting methods: 1. Heating or slowing down the revolution speed 2. Improving embryo tube quality 3. Reducing the embryo tube thickness, or trying to raise the outer cover of the heating device to increase the temperature dissipation of the embryo tube surface
Fault 3: The water outlet position at the bottom of the PET bottle is offset
Reasons: 1. The blowing time starts too early 2. The stretching rod is not down to the bottom 3. The stretching rod is offset from the center line of the bottle axis 4. The wall thickness of the embryo tube is uneven or the injection density is uneven 5. Uneven heating
Troubleshooting method: 1. Delay the blowing time or increase the descent speed of the stretching rod 2. Adjust the position of the magnetic pole switch 3. Adjust the position of the stretching rod 4. Improve the quality of the embryo tube 5. Improve the heating conditions, or check whether there is a problem with the self-rotation of the embryo tube
Fault 4: Uneven wall thickness of PET bottle
Reason: 1. The position of the stretching rod is not in the center of the embryo tube 2. The blowing holes are asymmetric and the apertures are different 3. The stretching ratio is too low or the blowing ratio is too small 4. The embryo tube does not rotate in the heating furnace 5. The wall thickness of the embryo tube is uneven or the injection density is uneven
Troubleshooting method: 1. Adjust the position of the stretching rod 2. Adjust the position and aperture of the blowing hole 3. Increase the stretching ratio or blowing ratio 4. Check the self-rotation device 5. Improve the quality of the embryo tube
Fault 5: The upper part of the bottle is too thick
Reason: 1. The upper temperature is too low 2. The position of the mold exhaust hole is too far from the upper part 3. The stretch ratio is too low 4. The blowing ratio of the upper part of the bottle is too low 5. The stretch rod speed is too slow
Troubleshooting methods: 1. Heat the upper part 2. Adjust the position of the exhaust hole 3. Increase the stretch ratio 4. Change the bottle shape 5. Adjust the stretch rod speed
Fault 6: The bottom of the bottle is too thin
Reason: 1. Start blowing too early 2. The bottom temperature is too high 3. The bottom of the embryo tube is too thin
Troubleshooting methods: 1. Delay the start of blowing 2. Reduce the bottom temperature 3. Increase the thickness of the bottom of the embryo tube