The important factors influencing the PET bottle blow molding process respectively

The important factors influencing the PET bottle blow molding technology has a bottle preform, heating, blow, blow molding bottle preform mould and environment preparation, will first PET chip for bottle preform injection molding, it requires that the secondary recycling material ratio cannot be too high ( Less than 5%) Number cannot exceed twice, and recycling and low molecular weight and viscosity can't ( The molecular weight of 31000 - 50000, characteristic viscosity of 0. 78 - 0. 85立方厘米/ g) 。 Injection molding of bottle preform need to store more than 48 h before use. After heating unused bottle preform, must be reheated to store more than 48 h can use again. A bottle of billet storage time can't more than six months. Bottle preform quality depends largely on the merits of the PET material, should choose the material easy to blow, easy to finalize the design, and formulate reasonable bottle preform molding process. Experimental results show that the same viscosity of PET bottle preform materials forming, imported raw materials than domestic material for blow molding; And the same batch of bottles billet, production date, blow molding technology may also have bigger difference. Bottle preform quality decides the difficulty of blow molding process, the requirement to the bottle preform is pure and transparent, without impurities, no color, length and halo around the spot right on point. Heat the bottle of billet heating are done by the heating oven, the temperature by artificial setting, automatic adjustment. In the oven by the far infrared lamp emit far infrared ray to preform radiation heating, thermal cycle by fan at the bottom of the oven, make the evenness of temperature in the oven. Bottle preform forward movement and rotation in the oven, make the bottle preform wall heated evenly. Tubes of cloth 臵 from top to bottom in the oven show 'area' glyph, commonly more than two head, less in the middle. Oven heat from the tubes open quantity, the overall temperature setting, oven heating power and paragraphs than common control. Lamp of open to combine beforehand to adjust the bottle blowing. To make the oven to work better, its height, the adjustment of the cooling plate and so on is very important, if improper adjustment, easy to appear when blowing bulge bottle ( Bottle) Hard, head and neck ( The neck is expected to pull doesn't open) Wait for blemish. Preliminary forecast wind is a two step method of bottle blowing very important one step, it refers to the blow molding process at the beginning of the tensile rod falling while blowing, make the bottle preform begun to take shape. The process of blowing a 臵, blowing blowing pressure and flow rate are three important technological factors. Advantages and disadvantages in the process of the bottle shape determines the quality of difficulty and the performance of the bottle blow molding process. Normal bottle shape for spindle, of anomaly is fluid, handle, etc. , as shown in figure 2. The causes of abnormal shape are local heating is undeserved, blowing blowing pressure or flow is insufficient, etc, in particular the size of the bottle blowing depends on wind pressure and blow a 臵 beforehand. To maintain the equipment in the production of all bottle size and shape is consistent, if there are differences to find the specific reason, can be adjusted according to the pre bottle blowing conditions heating or blowing process. Preliminary blowing pressure varies with the size of the bottle and varies specifications, equipment capability, general and large capacity, smaller pre blowing pressure; Equipment production capacity, high pressure is high. Even with the same equipment production the same specifications of the bottle, because of the difference of PET material performance, it needs blowing pressure are also different. Glass fiber enhanced PET materials, smaller pressure can make the bottle at the bottom of the macromolecular orientation; Other materials, improper or not appropriate bottle preform molding process, note there are a lot of stress concentration near not easy fade, if blow molding, often in broken note points or in stress tests from the injection point blowout, leakage. Conditions according to the orientation, at this time to remove 2 - such as shown in the tubes 3 to note above open, heating to make note points, provide enough quantity of heat, to promote its rapid orientation. For heating have secondary use bottle preform or storage time exceeds the bottle preform, arithmetic effect due to the temperature, the molding process which is similar, compared with the normal bottle preform, the requirement of less heat, pressure can also be reduced. 2. 4 auxiliary machinery and moulds auxiliary refers to maintain constant temperature of the equipment. Mold temperature to play an important role in maintaining the stability of the products. Average body temperature is high, the bottom temperature is low. For cold bottle, due to its at the bottom of the cooling effect determines the degree of molecular orientation, at 5 - temperature control 8 ℃ is preferred; While thermal bottle at the bottom of the temperature is much higher. Mold is the important factors influencing the PET bottle blow molding process, mold shape quality will reduce or increase the difficulty of the process adjustment, such as reinforcement, arc transitional area and at the bottom of the cooling conditions and so on all have an impact on process adjustment. The stand or fall of environmental production environment also have great influence to process adjustment, the condition of constant can maintain the stable process and the stability of the products. PET bottle blow molding generally at room temperature and low humidity conditions is preferred. Three other requires pressure bottle should be at the same time satisfy the requirement of stress test and compression test. Stress testing is to prevent the PET bottle filling beverage bottle and lubricant ( Alkaline) During the process of contact with the degradation of molecular chains and cracking, leakage of internal quality control; Withstand voltage test is to prevent the bottle after filling the certain pressure gas generation blowout of the quality control. To satisfy these two needs, the thickness of the center point to control within a certain range, the general situation is the center of thin, stress testing is good, low pressure; Center of thick, better withstand voltage test, stress test is poorer. Of course, the result of the stress test also with the build-up of transition zone around the center of the material has a lot to do, it should undertake adjustment according to the practical experience