Blow molding product factory deep drawing hollow blow molding product molding process method

Author: MULAN -Plastic Molding Manufacturer

Hollow plastic molding machine is one of the three leading products of my country's plastic machinery, which basically meets the needs of ordinary hollow blow molding products. With the rapid development of the plastic packaging industry, the variety and specifications of products have expanded and increased. Plastic products are more complex in shape and have corresponding functions. The field of blow molding products has expanded to office supplies, household appliances, furniture, cultural and entertainment products and auto industry parts, such as: desktop boards, gasoline tanks, tool boxes, logistics pallets, agricultural vehicle roofs, etc. These have high molding technology content and use functionality, so they are also called "engineering blow molding". Due to the high comprehensive performance of blow molding products, low mold cost and equipment cost, more and more products appear in hollow blow molding products on the market. As the shape of extrusion blow molding industrial parts becomes more and more complex, the uneven distribution of wall thickness becomes the bottleneck of the development of extrusion blow molding technology. In particular, some products with small local space and large stretch ratio are difficult to be formed by ordinary blow molding process. General blow molding: the parison extends to the inner wall of the mold cavity through the internal air pressure in the mold to fit the inner wall, and maintains a certain pressure to shape the shape to obtain the product. However, some products have a relatively large local stretch, and the parison is stretched and thinned along the inner wall of the mold cavity when it is inflated, which will make the wall thickness of the parison in these parts too thin, resulting in the failure to form the product. Here we introduce the deep drawing blow molding process. Regarding the deep drawing hollow blow molding process, it means that without changing the shape of the blow molded product, through a special molding process, these parts that are not easy to inflate and the uneven wall thickness can be improved and the required shape can be obtained. . Deep drawing hollow blow molding technology is mainly used for hollow blow molded products with complex stretching ratio. If the hollow blow molded products can achieve uniform wall thickness around the product through conventional blow molding process (to meet customer needs) and easy Forming, you do not need to use deep drawing hollow blow molding. In the application of deep drawing hollow blow molding technology, it is necessary to make special improvements to the mold or equipment, which will increase the initial cost. There are three methods of deep draw blow molding that are practical. 1. Inclined deep drawing forming process The inclined deep drawing forming process requires a rotatable mold clamping mechanism. This molding method is only suitable for blow-molded products with a relatively large half-side stretch. It is pre-filled into the cavity by the weight of the parison, and the molding stretch ratio is reduced during inflation molding to improve the wall thickness of the product and increase the yield. . The oblique deep drawing forming process is as follows: 1. The mold is opened and rotated to a suitable position; 2. Die blanking and adjust the speed of blanking and mold displacement according to the actual situation; 3. After the blank reaches the designated position, the mold is closed, and the internal inflation is formed; 4. Before taking out the product, rotate the mold to a horizontal position, open the mold and take out the blown product. 2. Deep drawing auxiliary mold forming process The deep drawing auxiliary mold forming process needs to add a profiling intermediate mold. During preforming, the blank is extruded to some areas with relatively large stretch through the intermediate mold, and only the area with relatively small stretch is formed during forming. In this way The molding process becomes simple and easy. When this deep drawing molding process is adopted, it can satisfy blow molding products with relatively large stretching on both sides. The forming process of the deep drawing auxiliary mold is as follows: 1. The machine head extrudes two sheets; 2. When the sheet reaches the relative position, the auxiliary mold intervenes; 3. The main mold is closed, so that the parison is extruded into the deeper side of the mold cavity; 4. The parison moves simultaneously with the main mold (mold opening), and the auxiliary mold exits; 5. After the auxiliary mold is pushed out, the main mold is closed, and air is blown inside to keep the pressure; 6. After pressure-holding molding, the main mold is opened, and the blow molding product is taken. 3. Rotating petal deep drawing forming process The rotary petal deep drawing forming process is realized through the improvement of the mold, and the side wall of the mold needs to be equipped with a rotary opening device. The rotating petal deep drawing molding process can meet the blow molding products with relatively large stretching of the side walls on both sides. The rotating petal deep drawing process is as follows: 1. The machine head extrudes the parison to a certain position; 2. The cavity on the deeper side is opened at a certain angle, and the parison is properly bulged; 3. Reset, clamp and inflate the deep side cavity; 4. Pressure-holding molding, mold opening, and blow molding products. The above three deep drawing forming processes can produce such products with relatively large stretching. Their main feature is that before the product is formed, the parison is allowed to enter the mold cavity to reduce the drawing ratio during forming, thereby Get good blow molded products. In the actual application process, we need to understand the shape and characteristics of the product, and adopt a reasonable deep-drawing molding process according to blow-molded products of different complexity. The following is our understanding of the three deep drawing forming processes. 1) Application range and advantages of inclined deep drawing forming process The inclined deep drawing molding process is mainly used in blow molding products with relatively large unilateral stretching; because the parison is extruded and the mold is moved, the effect of parison drooping is minimal, and the wall of each part can be freely controlled for long-process products. Thickness precision; Compared with the other two deep drawing forming processes, the mold is simple, the forming efficiency is high, and the cycle is short. 2) Application range and advantages of deep drawing auxiliary mold forming process The deep drawing assisted molding process is suitable for blow molding products with a large draw ratio on one or both sides. During the parison blanking process, it must be a sheet and the flash material must be sufficient; Compared with deep-drawing rotary die-assisted molding, the die is simple and only needs to add a copy die. No matter how complicated the product is, during pre-forming, the parison in the die can be squeezed and attached to the inner wall of the die by the auxiliary die. ; This molding method not only has a relatively uniform wall thickness, but also can be made into a right angle around the corner, and the bottom corner does not have to be deliberately rounded to prevent the wall thickness from thinning. 3) The application range and advantages of the rotary petal deep drawing process The rotary petal deep drawing molding process is only suitable for blow molded products with a relatively large stretch in the side wall area; compared with the other two deep drawing molding processes, the rotary petal deep drawing molding process blow molding equipment does not require any modification. However, the mold processing is more complicated; the rotary petal deep drawing forming process is composed of several parts: the die body corresponding to the bottom of the product and the four surrounding die side plates are installed through hinges and driven by oil cylinders respectively. The four side panels can work by opening or closing like flower petals. Collected and edited from industry journals, providing learning exchanges. For more information on blow molding products, please follow Proficient Blow Molding.