What are the factors that affect the bottle blowing machine?

The factors affecting the bottle blowing machine include the bottle blank and its heating, pre-blowing (position, pressure and flow), stretching rod, high-pressure blowing (pressure and position), and mold, etc. Now let's give you a detailed introduction.
1. Bottle preform, also known as parison, is formed by injection of PET pellets. It requires that the proportion of recycled materials should not exceed 10% and the number of recycled materials should not exceed two. The preform after injection molding or the preform after heating can be cooled for more than 48 hours, and the storage time of the preform used can not exceed 6 months. Different dates, especially the preform with long interval, can not be mixed. The main reason is that the model of raw materials used for the preform, the proportion of mixed secondary materials and the residual stress in the preform are different, and these factors have a significant impact on the molding process of bottle blowing, which should be treated according to the actual situation.
2. The heating of the bottle preform is completed by the heating furnace, which is set manually and adjusted automatically. The height of the heating furnace should be about 25mm, about 19.6mm from the conveyor wheel. The bottle preform runs continuously on the conveying wheel and passes through the whole oven, so that the bottle preform is heated evenly and can be formed, which overcomes the disadvantages of uneven heating caused by static heating and manual rotation of the bottle preform. However, if the heating furnace is not adjusted properly, it will cause uneven distribution of the wall thickness of the blown bottle (light as above and heavy as below), oversized bottle mouth, hard neck and other product defects, and even cause mechanical component torque failure. The company's main automatic bottle blowing machine. The heating temperature of bottle preform is generally set at 85-120 ℃, the colorless bottle preform is higher, and the colored bottle preform is lower. If the temperature is set too high or too low, it will cause product defects, such as tear, white fog, etc. The temperature of each area can be adjusted according to the molding conditions of the products, and the opening of the oven lamp tube should be considered. In addition, the setting of the oven output power also has a great impact on the heating of the preform, which controls the heat output of the entire oven. When the machine is not started for a long time and is started again, the initial output power should be set higher, and then gradually reduced to the normal state during the normal process. The output power is generally about 80%, especially when the ambient temperature is below 5 ℃, the effect is more significant. The bottle blowing process is also related to the ambient temperature. The ambient temperature is generally room temperature (about 22 ℃). If the temperature is too high, the product is prone to agglomerate; The temperature is too low, and the product performance is unstable when the machine is started. The specific operation should be adjusted according to the actual situation and experience.
3. The role of pre-blowing and pre-blowing in the blowing process is to make the preform take shape, and at the same time, its longitudinal strength is increased by the longitudinal stretching of the stretching rod. The whole process is that the pre-blowing cam pushes the three-way valve to the pre-blowing position during the bottle blowing process, and is completed with the cooperation of the one-way valve. The pre-blowing position, pressure and flow can affect the quality of the bottle. If the pre-blowing position is advanced, the center point at the bottom of the bottle will be skewed and thinner, the wall thickness of the foot will be uneven and white, the top will be heavy and the bottom will be light, the neck will be hard, and even the bottom will penetrate; If the pre-blowing position is wrong, defects such as light up and heavy down, thickening of the center point and depression will appear. Air flow Pre-blowing air flow is controlled by one-way valve, generally 3-4 turns is appropriate. Large air flow, heavy bottom, thin and eccentric center point, white feet, uneven wall thickness; The air flow is small, the center point is thickened, and the weight of segmented parts exceeds the standard. The pressure pre-blowing pressure should be 0.8-1MPa. When the pressure is high, it may cause the upper weight to be light, the center point to be skewed, the foot wall thickness to be uneven, and whitening; When the pressure is low, it cannot be fully stretched, the bottom is heavy, and the center point is thick. The molding of the bottle foot and center point has a great impact on the quality of the bottle. Improper adjustment often causes fatal defects such as bottle explosion (under normal experimental conditions) and leakage.
4. The function of high-pressure blowing is to make the molten material fully extend and close to the mold wall, so that the bottle can be fully formed, and at the same time, it can be stretched horizontally to improve its transverse strength. The main influencing factors are location and pressure. The high-pressure blowing pressure is generally 3.7-4MPa, which is determined by its molding characteristics and the nature of the filled beverage (carbon dioxide). There are two positions, that is, the position of high pressure gas and the position of exhaust gas. The time between them is the pressure holding time in the molding process. The length of this time has a great impact on the stability of the bottle capacity. Insufficient high pressure gas is easy to cause improper bottle forming and insufficient foot blowing.
5. Stretching rod Stretching rod is a device to stretch the heated preform under the cooperation of pre-blowing and pre-blowing, and it is reset after high-pressure blowing and before exhaust. The stretching rod can move vertically and steadily up and down during bottle blowing, the driving pressure is 0.55-0.8MPa, and the gap with the bottom mold is 2.3-2.5mm, that is, the bottle blank thickness is 1/3-1/2. If the gap is too large, the center point of the bottle bottom will shift; The gap is too small, and the center point becomes thinner.
6. The mold is one of the important factors that affect the bottle blowing molding. The bottle body is a Huff mold, and the bottle bottom is independent, which is a typical blow molding mold. During the process, the mold should be kept constant temperature, clean and exhaust hole. When the heating and cooling system of the mold fails, there will be defects such as skewed bottle neck, inclined bottle, volume and height changes, and heavy bottom; Maintaining the mold constant temperature can also prevent the mold surface from condensation. The shrinkage of PET after molding is relatively large, generally 1.8%, and slightly decreased after adding glass fiber reinforcement, but still up to 0.2% - 1.0%. In general, the shrinkage at high mold temperature is large, and the shrinkage at low mold temperature is small. In order to maintain the stability of PET bottle volume, the mold temperature should be strictly controlled. Generally, the temperature of the bottle body is required to be slightly higher, 20-45 ℃, and the bottom is required to be lower, 6-15 ℃. High bottom temperature will make the bottom heavier and the center thicker. The experts of the automatic bottle blowing machine concluded that there are nozzles that will affect the forming of PET bottles in practice.