Common quality defects in bottle blowing packaging materials and solutions (III)
11、 Neck crease (commonly known as' band ')
Symptoms: The internal folds are usually seen at 5-8mm below the convex ring, which is obviously in the shape of a ring, and there are obvious folds when touching the outside.
Factors: It is all related to the fact that the embryo is too easy to stretch from the thinner end of the cone section. In severe cases, the stretching will start from the parallel section below the convex ring. When the bottle embryo is stretched, it will gradually cool down with the stretching rod downward, while the material at the second place is thin, which will also cool quickly. Natural wrinkles occur during bottle blowing.
1. Re adjust the hot spot position so that it is close to the bottle embryo body.
2. Adjust the pre blowing air inlet time to ensure that it is not too late. Check whether the pre blowing solenoid valve is normal.
3. Blowing nozzle failure. It is necessary to check whether the upper and lower operation of the nozzle cylinder seal, diffuser, spring, solenoid valve and fixing sleeve is smooth (these will cause the nozzle to run slowly).
4. The materials in the area are very thin. Increase the material thickness of the area (reduce the temperature of the area or increase the temperature of the area where the bottle is thicker).
12、 Bottleneck material accumulation (commonly known as' flower neck ')
Symptoms: Bottleneck deposits are commonly seen at 5-8mm below the convex ring with wavy stripes, and the convex ring is irregular or elliptical.
Factors: When the bottle embryo is sent to the mold cavity by the transfer arm and touches the cooled mold cavity, it is cooled first or the bottle embryo is blown into the air too early during stretching, then the bottle embryo is formed when stretching along with the stretching rod downward.
1. The pre blowing pressure is too high.
2. The pre blowing intake time is too early.
3. The temperature of Zone 1 is not enough (increase the heating percentage of Zone 1 or increase the number of lamps).
4. The lamp holder is too high. Adjust the position of the lamp holder.
5. The temperature in Zone 2 is too high or the temperature in other zones is too high (it is necessary to adjust the temperature in each zone according to the actual partition weight and thickness of the bottle to reduce the bottleneck material).
Symptom: The bottle bottom structure is not concentric with the container, which may cause whitening of the bottom corner in severe cases. The stress at the bottom of the bottle is poor, and it is easy to crack or burst.
Factor: This problem is related to two points. To identify which point needs to observe the position of the stretching point of a pull-down rod. If the position of the stretching point is eccentric with the pouring point at the bottom of the bottle embryo, it indicates that the stretching rod is not aligned with the mold. If the position of the stretching point is concentric with the pouring point of the bottle embryo, it indicates that the stretching rod is offset during bottle blowing although it is positioned correctly.
A. Mechanical causes
1. The bottle embryo is not aligned with the mold.
2. The blowing nozzle is not aligned with the mold.
3. The bottle embryo is too tight with the upper part of the mold.
4. The stretching rod is arched.
5. Tension bar sliding guide or linear bearing is abnormal.
6. The buffer pad of the stretching rod is not adjusted properly, causing the stretching to drop slowly or not completely.
B. Electrical fault
1. The pre blowing pressure is too high.
2. The pre blowing intake time is too early
3. The stretching lever solenoid valve is dirty, the control valve seal is worn or the coil reel is broken.
4. Exhaust of stretching cylinder is blocked (muffler is blocked).
5. The control pressure of the stretching cylinder is low (loss of the air circuit during turning).
14、 Pearlescent - white bottom corner
Symptoms: Pearlescence exists in any part of the bottle, but it is most common in the bottom corner of the bottle. It is normal for a small amount of bottle bottom corner to turn blue, which indicates that the bottle blowing process has achieved greater two-way stretching.
Factors: Pearlescence is the direct result of stretching beyond natural stretching. In fact, it is due to the tensile tearing of the material's microstructure. The materials in this area are obviously thin.
Solution: Because the materials in this area are thin, you can add more materials in this area. If the materials in this area are enough, consider the following reasons:
1. Make sure not to be eccentric.
2. Extend the pre blowing time and pre blowing air inlet time. Reduce the pre blowing pressure.
3. Make sure that the extension gap is correct (2/3 of the bottom thickness of the blown preform). Too much clearance will cause whitening.
4. Ensure that the extension runs flexibly and smoothly (if the extension runs up and down slowly, it will turn white).
5. The lower temperature of bottle embryo or the lower overall temperature of bottle embryo during heating.
15、 Whitening (bottle body, bottle shoulder)
Symptoms: Albinism is common in bottle blowing, and the most common is the whitening of the bottom corner (which has been mentioned in the previous section). For whitening, it is necessary to be able to distinguish whether it is high temperature whitening or low temperature whitening. Low temperature whitening is foggy and opaque. Whitening at high temperature is pearlescent and transparent.
Factors: A. Low temperature whitening - increase the temperature of the area or increase the overall heating percentage and bottle embryo temperature.
B. High temperature whitening - reduce the temperature of the area or the overall heating percentage and the bottle embryo temperature.
C. Another situation is that if the bottles in other bottle blowing stations are of good quality and the bottles in individual bottle blowing stations are whitened, two aspects should be considered.
1. The pre blowing pressure is low.
2. Blowing nozzle leaks. (The blowing nozzle is high or the height on both sides of the mold is different)
In this case, the bottle is usually whitened at the waist or from top to bottom