Views: 684 Author: Site Editor Publish Time: 2020-01-21 Origin: Site
Supersonic flame is a high-temperature, high-speed combustion flame, generated by burning propane, propylene and other hydrocarbon-based gas or hydrogen and high-pressure oxygen in the combustion chamber, or in a special nozzle. And the speed of flame can reach Mach 5 (1500m/s. ) or above, commonly referred as HVOF (High-velocityoxygen-fuel). By feeding the powder axially into the flame, which could heat the sprayed particles to a molten or semi-molten state, and then accelerate up to 300-500m/s or more, the high-strength, dense and high-quality coatings could then be obtained. The supersonic flame has high speed but low temperature relatively. For WC-Co cemented carbide, it can effectively inhibit the decomposition of WC during the spraying process. So that not only the high bonding strength, the coating is also of high dense and excellent wear resistance. Its wear resistance greatly exceeds that of plasma spray coating, electroplated hard chromium layer or spray melt layer, and is equivalent to that of explosive spray coating. The flame is widely used in producing single-screw and twin-screw, and has been affirmed in actual use.
the wear-induced failure of screws and barrels, noting the limitations of chrome plating and nitriding. It investigates the feasibility of surface boriding treatment on 45 steel screws and barrels to enhance surface hardness and wear resistance, and validates the process through field testing.
This article introduces the working principle of ball screws, highlighting their high mechanical efficiency and load capacity, which have led to widespread adoption in all-electric servo-driven injection molding machines. It compares ball screw design philosophies for machine tools and injection molding machines, noting that injection units experience loads hundreds to thousands of times greater. Key design priorities for high-load ball screws—such as uniform ball contact pressure, optimized lubrication, and enhanced durability—are discussed, with reference to Ningbo Superior's specialized solutions.
The screw and barrel are the most critical components of injection molding machines, operating under high temperature and pressure. Wear enlarges the clearance between the screw flight and barrel, reducing melting and pumping capacity, causing product quality degradation, lower productivity, and higher energy consumption. The screw is more susceptible to damage than the barrel.
This section examines the key parameters of the venting section in vented extruder screws. Venting effectiveness depends primarily on venting section length L, melt residence time, shear rate, and the fill factor F (the ratio of melt cross-sectional area to channel area). To ensure good performance, the venting channel should be partially filled; experiments suggest L ≥ 3D, F ≤ 0.5, and a shear intensity K > 100 for optimal degassing. For screws with L/D ratios of 24–30, the venting section length is typically 4D, and its channel depth is 2.5–6 times that of the first metering section. Design verification must include fill factor, shear intensity, and screw strength.
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This section discusses the determination of channel depths H₁ and H₂ in venting screws, with emphasis on the pump ratio Ω (Ω = H₂/H₁). The pump ratio directly influences the risk of vent flooding and extrusion stability. A theoretical optimum Ω of 1.5 is derived for Newtonian fluids, while for non-Newtonian polymers like polyethylene an Ω of 1.75 yields maximum die pressure. In practice, most designs adopt Ω values between 1.5 and 2.0. The article also clarifies that the concept of a "second compression ratio" is invalid for venting screws, as the venting section is not fully filled.
