Free-falling double-nozzle powder mixing gas atomizing water-cooling fast-setting metal matrix CBN magnetic abrasive preparing method

Abstract

The invention provides a free-falling double-nozzle powder mixing gas atomizing water-cooling fast-setting metal matrix CBN magnetic abrasive preparing method. The method is characterized in that CBN powder is adopted as hard abrasive of magnetic abrasive, and an alloy composed of iron, silicon, aluminum and copper is adopted as a metal matrix material; upper and lower layer free-falling nozzles are adopted as nozzles, the upper layer free-falling nozzle is a low-pressure mixed powder flow jetting nozzle, and the lower layer free-falling nozzle is a high-pressure gas flow nozzle; water cooling is adopted as a cooling manner, and by adjusting the height of the water level of cooling water in an atomizing and water cooling chamber, the cooling speed of molten metal drops containing the CBN abrasive is controlled, so that the CBN abrasive forms the magnetic abrasive distributed on the surface shallow layer of a magnetic abrasive metal matrix; a spiral mixed powder conveying device is adopted for conveying mixed powder, so that flow of the CBN abrasive is controlled precisely. According to the prepared metal matrix CBN magnetic abrasive, CBN and the metal matrix are combined firmly, the magnetic abrasive has high magnetic abrasive performance, the production technology process is controlled in a programmed manner, product performance is stable, and the method is suitable for scale production.

Description

technical field [0001] The invention provides a method for preparing a free-fall double-nozzle mixed powder gas atomization water-cooled fast-setting metal-based CBN magnetic abrasive, which belongs to the technical field of composite material preparation. Background technique [0002] From the perspective of material science, magnetic abrasive is a composite material, that is, an iron-based reinforced composite material, which is mainly composed of a ferromagnetic phase and an abrasive grain phase. The ferromagnetic phase requires good magnetic permeability and electrical conductivity, and the commonly used materials are pure iron powder or iron-based alloy powder. Abrasive phase is a kind of granular substance with high hardness, strength and stability, which has the functions of grinding, grinding and polishing. The commonly used materials are corundum, CBN, silicon nitride, silicon carbide, etc. The chemical composition, ratio and structure of the magnetic abrasive are ...

AI Technical Summary

Problems solved by technology

The current problem of the reaction casting method is that the content of ceramic hard abrasive in the magnetic abrasive is low and the particle size of the hard abrasive is difficult to control

Although this method solves the problem of poor compatibility between the iron-based phase and the abrasive phase, the magnetic abrasive prepared by this method is subjected to the high temperature of the plasma flame, and the sharp cutting edge of the abrasive grain phase is passivated, resulting in a significant reduction in grinding efficiency. , its grinding ability is even inferior to that of magnetic abrasives prepared by other simple methods

[0011] At present, the main problems of magnetic grinding and finishing are the low service life of magnetic abrasives, poor metal cutting ability, difficult preparation and high cost.

[0012] (1) Jet nozzle problem: due to the use of a single nozzle, the jet velocity of the gas-solid two-phase flow is high, resulting in rapid erosion and wear of the jet nozzle, and it fails in a very short time, and the preparation function of the magnetic abrasive is lost; at the same time, it is also due to the A single nozzle is used, and the hard abrasive and high-pressure gas are used as the atomizing medium. If the jet velocity of the gas-solid two-phase flow is low, the atomization effect will be poor and the magnetic abrasive particles will be coarse. However, if the jet velocity of the gas-solid two-phase flow is high, although the magnetic Although the particle size of the abrasive is reduced, the hard abrasive will splash out again after entering the molten metal, resulting in a sharp decrease in the hard abrasive contained in the metal matrix of the magnetic abrasive, and the grinding performance of the magnetic abrasive is significantly reduced

[0013] (2) Erosion and wear of the molten metal guide tube: the tightly coupled atomization method is adopted. Before the molten metal flow is atomized, the gas-solid two-phase flow is first sprayed onto the lower end of the molten metal guide tube, causing The lower end of the molten metal diversion pipe has serious erosion and wear in a short period of time, which leads to the risk of back spraying of molten metal and high-pressure gas along the molten metal diversion pipe

[0014] (3) Condensation rate control of liquid magnetic abrasive droplets: Since the problem of accurate control of condensation rate of molten magnetic abrasive droplets has not been solved, the prepared magnetic abrasives have been unstable in depth distribution of hard abrasives in the metal matrix. Affect the grinding ability of magnetic abrasives, and the scrap rate is high

[0015] (4) The content control of hard abrasives in magnetic abrasives: due to the difficulty of accurately controlling the flow rate of hard abrasives in gas-solid two-phase flow in the pneumatic powder mixing device, the content of hard abrasives in magnetic abrasives is unstable and the magnetic abrasives Unstable performance

[0016] (5) The problem of erosion and wear of the molten metal guide tube: using the tightly coupled atomization method, before atomizing the molten metal flow, the gas-solid two-phase flow is first sprayed onto the lower end of the molten metal guide tube, causing The lower end of the molten metal diversion pipe has serious erosion and wear in a short period of time, which leads to the risk of back spraying of molten metal and high-pressure gas along the molten metal diversion pipe

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