The quality of production also has a great impact on process adjustment. Constant conditions can maintain process stability and product stability. PET bottle blow molding is generally preferred at room temperature and low humidity. The arrangement of the lamps in the oven is generally square-shaped from top to bottom, with more ends and less in the middle. The heat of the oven is controlled by the number of lamps, the overall temperature setting, the oven power, and the heating ratios of the sections. The lamp should be adjusted in combination with the pre-blowing bottle. Even if bottles of the same specification are produced from the same equipment, the required pre-blowing pressure is different due to the difference in performance of the PET material. Glass fiber reinforced PET material, the small pre-blowing pressure can make the bottom of the bottle have a correct orientation; other materials with improper materials or improper molding process, a large amount of stress concentration near the injection point is not easy to subside, if blowing Plastic, often blows at the point of injection or bursts and leaks from the point of injection in the stress test. According to the orientation conditions, the lamp can be removed from the 2-3 rods as shown above to the top of the injection point, and the spot is sufficiently heated to provide sufficient heat to prompt its orientation. Important factors affecting the PET bottle blow molding process include preforms, heating, pre-blowing, molds, and the like. The adjustment of the PET bottle blow molding process is carried out for the corresponding materials. If the material is not good, the requirements on the process are very demanding, and it is even difficult to blow out a qualified bottle. The heating of the preform is done by a heating oven, the temperature of which is manually set and automatically adjusted. In the oven, far infrared rays are emitted from the far-infrared tube to heat the preform, and the fan at the bottom of the oven performs thermal circulation to make the temperature in the oven uniform. The preform is rotated while moving forward in the oven to heat the preform wall uniformly. For preforms that have been heated for secondary use or preforms that have exceeded the storage time, the molding process is similar due to the time-temperature difference effect. Compared with the normal preform, the required heat is less, and the pre-blowing pressure is also appropriate. reduce. The auxiliary machine mainly refers to the equipment that maintains the temperature of the mold. The mold constant temperature plays an important role in maintaining the stability of the product. Generally, the temperature of the bottle is high and the temperature at the bottom of the bottle is low. For cold bottles, because the cooling effect at the bottom determines the degree of orientation, it is better to control the temperature at 5-8 °C; the temperature at the bottom of the hot bottle is much higher. With the continuous advancement of technology and the scale of production, the PET bottle blowing machine is becoming more and more automated and the production efficiency is getting higher and higher. Equipment production capacity continues to increase, from the previous production of thousands of bottles per hour to the current production of tens of thousands of bottles per hour. The operation has also evolved from the past manual button type to the current full computer control, which greatly reduces the difficulty of the process operation and increases the stability of the process. Blowing machine and oven relationship When preparing the blow molding bottle, the PET slice is first injection-molded into a preform. It requires that the proportion of the secondary regrind should not be too high (less than 5%), the number of recovery cannot exceed two times, and the amount and viscosity cannot be Too low (amount 31000-50000, intrinsic viscosity 0.78-0.85cm3/g). Injection molded preforms must be stored for 48 hours to be used above. The preforms that have not been used up after heating must be stored for another 48 hours to be reheated. Preforms should not be stored for more than six months.
The oven acts during the blow molding process