Principle analysis of screw barrel of injection molding machine

Update:13 Feb 2019
Summary:

The screw speed of the screw barrel of the injection mo […]

The screw speed of the screw barrel of the injection molding machine can be realized as a stepless pressure and speed regulation configuration. The linear guide beam is used instead of the guide column type to reduce the friction at the time of injection and improve the injection accuracy (optional). The screw and the material tube are made of alloy material, quenched and tempered and desalinated to improve the wear resistance. The electronic ruler of the Italian Jeffron is used for injection, and the position control precision can be controlled at 0.1 mm. 4-stage injection pressure and speed, 4-stage holding pressure and speed independent control are more conducive to injection process adjustment. The manual back pressure device (CNC back pressure option) increases the plasticization, exhaust and density of the screw to the plastic. After the addition, the back pressure eliminating device is added to prevent the use of the back pressure of the feed during the production of the product without the plastic material flowing into the mold to generate the cold material.
 
  The screw barrel of the injection molding machine causes material degradation, which affects the quality of the product. What are the reasons for screw slip? How to "catch" the slippery screw? When the barrel screw is slipping, the material will collect at the feed port and cannot be normally delivered to the end of the injection machine. When the screw rotates and retreats in the barrel to transport the material and prepare for the next injection, the screw slip occurs in the plasticizing section. At this point, the rotation of the screw is still inherited, but the axial movement of the screw will stop, ie, slippage will occur. Screw slippage often causes degradation of the material prior to injection, product quality is reduced (eg, lack of material), and the molding cycle is extended.
 
  There are many reasons for the screwing of the screw barrel of the injection molding machine, which is probably too high with the back pressure, the end of the barrel is too hot or too cold, the barrel or screw is worn, the thread of the feeding section is too shallow, the hopper plan is unfair and the hopper is infested, resin Wetting, excessive lubrication of the resin, too small material, probably unreasonable cutting of the resin and recycled materials are related. Subcooling at the end of the barrel is one of the main causes of screw slippage. The barrel of the injection machine is divided into three sections. At the end, that is, the feeding section, during the heating and compression process, a layer of melt film is formed on the screw. Without this film, the pellets are not easily transported to the front end. The material of the feed section must be heated to a critical temperature of light to form a melt film of that layer. However, usually the residence time of the material in the feed section is very short and the required temperature cannot be reached. This environment is usually produced on small injection machines. Too short a residence time can result in incomplete melting and inclusion of the polymer, causing the screw to slip or stall.

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