Industry News

Home / News / Industry News / What are the process requirements of the blow molding machine mold?

What are the process requirements of the blow molding machine mold?

When designing and manufacturing Bottle Blowing Machine molds, in addition to considering the mold's impact on the performance and efficiency of subsequent product processing and production, but also considering the requirements of the product manufacturing process on the mold.
  (1) Exhaust of mold
The blow molding machine mold closing and parison inflation will release the gas in the mold at the moment. If the exhaust effect is not good, the gas remaining in the mold cavity will cause stripes, dents, unclear fonts, and unevenness on the surface of the product. , And even defects such as deformation. Therefore, this needs to be fully considered in the mold design and manufacturing, and the following common measures can be taken.
  1. Product surface design
  When designing the surface of the product, the characters, patterns or grooves should be designed in the mold to facilitate the exhaust of the mold. However, it is also necessary to avoid a large area of ​​smooth surface, or to engrave shallow patterns on the smooth surface, which is conducive to the exhaust of the mold.
   2. Mold cavity treatment
  Not all blow molding machine mold cavity surfaces are as smooth as possible. A slightly rougher cavity surface is not conducive to mold exhaust. It can also improve the surface effect of the product. Commonly used methods of cavity surface treatment include cavity surface sandblasting, surface etching pattern, cavity polishing and other methods. However, some products with very high surface requirements, such as cosmetic containers made of polystyrene, are not suitable.
  3. vent hole or vent groove
  The best way to solve the problem of mold exhaust is to open exhaust grooves or holes in the mold cavity and parting surface. Several common exhaust methods are as follows.
  (1) Open an exhaust groove on the parting surface of the mold
  Exhaust grooves are opened on the parting surface to exhaust air as much as possible. Generally, the exhaust grooves are designed at the shoulder and bottom of the parting surface, and they can be opened in positions if there are special needs. The width of the exhaust groove is generally 5-25mm; the actual choice of the exhaust groove should be based on the product production process, container volume and wall thickness, generally between 0.01 and 0.2mm. The larger the volume, the deeper the groove is. .
  (2) Open vent holes in the mold cavity
When the vent hole needs to be opened in the mold cavity, the diameter of the vent hole near the mold cavity is generally designed to be 0.1-0.3mm. If the diameter is too large, it will leave bumps on the surface of the product and affect the surface of the product. If the diameter is too small There will be pits again, and when designing the position of the vent in the mold cavity, it is necessary to consider not to interfere with the layout of the cooling system. For large-volume products, the diameter of the exhaust hole can be larger, and a specific exhaust plug is installed for exhaust. In addition, an exhaust groove can be provided at the insert in the mold cavity.
  (3) Vacuum exhaust
When making the mold of the hollow blow molding machine, drill some small holes in the cavity of the mold to connect them with the vacuum machine, which can extract the air left in the mold cavity, so that the blow molding parison and the cavity are closely attached . In addition, this method is also beneficial to some blow-molded products that need to be drawn, the inside of the blow-molded product cannot be inflated, the surface quality is required, and the sandwich is hollow. The control of the vacuum exhaust system needs to be combined with the electrical control system of the hollow molding machine in order to control the accuracy and performance.
   (2) Mold cooling
  The cooling of the mold of the automatic blow molding machine is one of the important molding process conditions, which directly affects and determines the production efficiency and product quality of the product. The design of the mold cooling system takes into account factors such as cooling location, cooling area, heat transfer efficiency, product cooling uniformity, cooling water temperature, flow, pressure, temperature and heat capacity of molten resin. Therefore, consideration should be given to the design of the mold's cooling system.
   Commonly used mold cooling channels include box cooling channels, drilling cooling channels, casting buried cooling channels, and laminated mold cooling channels. Either way, the arrangement of the cooling water channels should be below the mold, and the outlet should be above the mold, so that the cooling water can flow in the direction of natural heating.
   (3) Die cut and tailing trough
  In order to clamp and close the parison and cut off the parison tail, it is necessary to arrange cuts on the parting surface of the mold, such as the neck, bottom, handle and handle. The width of the cut depends on the type of material, the thickness of the parison, and the volume of the product, and it is generally between 1 and 4.5 mm. The incision is affected by the volume of the product and the thickness of the parison. If the incision is too shallow, the mold cannot be closed, and the parison is more difficult to cut. If the incision is too large, the parison tail material cannot be in contact with the mold and cannot be cooled. Generally speaking, the knife edge is 80% to 90% of the wall thickness of the parison. A tailing trough is provided at the outer edge of the die cut, which can store the cut-off part in the trough and locally thicken the joint of the product. The depth of the tailing groove also has a great influence on the product. The groove depth range used for different materials is shown in the recommended table. Generally, the groove depth is selected at 80%-90% of the wall thickness of the parison, which can increase the seam of the product. Thick role.