Defects will damage the service life of the rubber screw barrel and affect the safety of processing. At present, zhouhan intai screw manufacturing co., ltd. has developed an onyx anti-wear protection system for plasticizing screw, which can protect screw from wear and has high impact resistance.
To achieve an economically feasible life cycle, plasticizing screw with carbon metal coating is very important when processing professional composite materials with high additive levels. The carbon-containing coating ensures the necessary high wear resistance, while the steel under the coating bears the mechanical load and ensures high safety under impact stress by its excellent strength characteristics. The development project of Zhuoushan Intai Screw Manufacturing Co., Ltd. aims to improve the mechanical properties of carbonized steel composites, to apply the great potential of carbides to wear protection in long-term production and application.
In the coating, defects such as pinholes, cracks, and nonmetallic impurities (such as oxides or mud) are the main factors leading to metal fatigue. The wear mechanism of these defect areas is closely related to the long working life, so the manufacturing process must be optimized to avoid defects as much as possible, or at least minimize the possibility of defects.
Only straight and untwisted rod materials are used in the production of screws. The initial profile of the screw is obtained by milling or rotary cutting, which cuts off most of the material and releases the internal stress of the material. The metal needs to be annealed and remolded several times, to manufacture a semi-finished screw without stress. Subsequently, the carbide powder is heated to about 1200℃ in a burner and accelerated to the speed of sound or above (300m/s~2000m/s). At this speed, the semi-fluid particles hit the rough surface of the semi-finished screw and bond with the untreated workpiece. Adequate particle velocity can also ensure that even at the screw edge with a poor jet impact angle, there are almost no pinholes on the surface. Hot powder particles are rapidly cooled from 1200℃ to about 150℃, and the resulting volume contraction will lead to surface tension. Then, this tension is offset by the high-speed motion energy of particles, because the impact of particles will lead to plastic deformation of the surface layer and the formation of compressive strength. After 30~60 impacts, a uniform coating will be produced on the whole surface.
After that, the coating is annealed in inert gas or vacuum furnace. By heating the substrate, its microstructure changes from hollow cubic iron to hollow cubic austenite, and this microstructure change will not affect the coating. During this period, the alloy elements contained in the coating in the extreme thermodynamic imbalance state will produce diffusion compensation. The coating on the edge of the substrate will also change, thus improving the adhesion. After the heating period, the steel is cooled in several stages. The cooling rate has a great influence on the transformation of microstructure and the properties of screw substrate. Depending on the current process, the multi-stage cooling process with different cooling rates avoids the corresponding error sources, optimizes the performance of the layer and substrate, and ensures that the produced screw has no crack and almost no distortion. Targeted cooling means that the screw needs to be slightly straightened to maintain the required accuracy. Depending on the basic steel used for the screw, the required steel properties can be obtained by annealing and rough grinding at 400℃~650℃. After annealing and rough grinding, the screw is machined to obtain the surface roughness required when the plasticizing unit is used.
The new system is especially characterized by its improved durability, which is proved by the results of the drop hammer impact test. Compared with other coating systems, before the initial cracking, the maximum impact force of the falling hammer it can bear is 300% higher.