Wide mouth bottle blowing machine refers to the machine for blowing bottles. The simple explanation is that the machine can blow plastic particles (softened into liquid) or finished bottle embryo into bottles by technological means. Plastic hollow containers are widely used in beverage, medicine, cosmetics, food and chemical industries due to their light weight, low price and high safety. It has attracted many manufacturers to choose plastic containers to replace glass containers.
1. Preform
Bottle preform, also known as parison, is made of PET granules by injection molding. It requires that the proportion of recycled materials should not exceed 10% and the number of recoveries should not exceed two. The preforms after injection molding or after heating are cooled for more than 48 h, and the used preforms cannot be stored for more than 6 months. The preforms with different production dates, especially those with long intervals, cannot be mixed. The main reason is that the model of raw materials used in the preforms, the ratio of mixed secondary materials, and the residual stress in the preforms are different. These factors have a significant impact on the molding process of bottle blowing, and should be treated according to the actual situation.
2. Heating
The preform is heated by the heating furnace, manually set and automatically adjusted. The height of the heating furnace should be about 25 mm and about 19.6 mm from the conveying wheel. The preform runs continuously on the conveying wheel through the entire oven, so that the preform is heated more evenly and can be well formed, overcoming the shortcomings of the former preform that is heated unevenly due to static heating and manual rotation. However, if the heating furnace is not adjusted properly, the wall thickness of the blown bottle will be unevenly distributed up and down (as above, light and heavy), the bottle mouth will become larger and exceed the standard, the hard neck and other product defects will be caused, and even the torque failure of the mechanical parts will be caused. The temperature of each area can be adjusted according to the molding of the products, and the opening of the oven lamp shall 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 wide mouth bottle blowing machine is not started for a long time and is started again, the initial output power should be set higher accordingly, and then gradually reduced to the normal state during the normal production process. The output power is generally about 80%, especially when the ambient temperature is below 5 ℃, the effect is obvious.
The bottle blowing production process is also related to the production environment temperature, which is generally at room temperature (about 22 ℃). If the temperature is too high, the products are easy to agglomerate; The temperature is too low, and the product performance is unstable when the machine starts. The specific operation should be adjusted according to the actual situation and experience.
3. Preblowing
The role of pre blowing in the blowing process is to make the preform take shape initially, and at the same time, the longitudinal strength of the preform is increased by longitudinal stretching of the stretching bar. The whole process is that the pre blowing cam pushes the three-way valve to the pre blowing position in the process of bottle blowing, which is completed by the cooperation of the one-way valve. Pre blowing position, pressure and flow can affect the quality of bottles.
Position: if the pre blowing position is advanced, the center point at the bottom of the bottle will deflect and become thinner, the foot wall thickness will be uneven and white, the weight on the top and the weight on 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 upper and heavy lower, thickened central point, and dents will appear.
The air flow pre blowing flow is controlled by a one-way valve, and it is generally advisable to open it 3-4 times. The air flow is large, the bottom is heavy, the center point is thin and partial, the feet are white, and the wall thickness is uneven; The air flow is small, the center point is thickened, and the sectional pieces are overweight.
Pressure: the pre blowing pressure should be 0.8-1MPa. When the pressure is high, it may cause the upper part to be heavy and the lower part to be light, the center point to be skewed, the foot wall thickness to be uneven, and the foot to be white; 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 the center point has a great impact on the quality of the bottle, and improper adjustment often leads to bottle explosion (under normal experimental conditions), leakage and other fatal defects.