The key technology that needs to be solved for gear hobbing MQL micro-lubrication

  • (1)High hobbing speed Generally, in dry hobbing processing, for coating (TiAlN) high-speed steel hobs The linear speed is required to reach 180m/min or even higher; the linear speed of the hard alloy steel hob is required to reach 300 m/min. In order to realize this kind of high-speed hobbing processing, the tool spindle can generally be realized by an electric spindle; for the worktable, a newly designed gear transmission system with automatic clearance elimination is used to replace the traditional worm and worm gear transmission system, LIEBHERR, GLEASON The worktables of high-speed gear hobbing machines of other companies have adopted torque servo motor technology, and the worktable speed can reach more than 800 r/min.
  • (2) Quick separation of chips Due to the high temperature, if the chips cannot be quickly separated from the tool, workpiece and machine tool, it will easily cause thermal deformation and affect the machining accuracy, so it must be fast and effective Remove iron filings.
    In dry hobbing, the high-speed hobbing of the hob is generally used to make the iron filings quickly leave the tool and the workpiece. Many companies have also put forward some machine tool structural improvements in response to the chip removal problem, such as using gravity to speed up the removal of iron filings, and avoiding the iron filings from directly falling on the workbench, and then assisting with high-pressure cold air to achieve rapid and effective chip removal. Some companies also use stainless steel heat shields,
    On the one hand, the surface of stainless steel is smooth, which facilitates the removal of iron filings.
    On the other hand, the thermal conductivity of stainless steel is small, which reduces the heat transfer of iron filings to the workbench and bed.
  • (3) High-speed hobs The hob materials for dry hobbing use cemented carbide steel in the early stage of development. However, due to the high cost of cemented carbide steel hobs, the powder metallurgy high-speed Steel hobs and TiAlN coated high-speed steel hobs have a tendency to replace hard alloy steel hobs for dry hobbing. In a research report, Liebherr Company has performed the processing of hard alloy hob (Carbide) dry hob, powder metallurgy high-speed steel hob (HSS-PM) and conventional high-speed rigid hob (Conv.HSS). The time and processing cost are compared. Comparative analysis results show that, compared with conventional machining, dry hobbing has shorter processing time and lower cost; the use of powder metallurgy high-speed steel hobs even has better dry hobbing results than the use of cemented carbide steel hobs .

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