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Knife safety measures in detail

Update:10 Jul 2017

       Combined with high-speed milling cutter safety s […]

       Combined with high-speed milling cutter safety standards, through the finite element calculation model analysis, in order to meet the safety requirements, the following measures can be taken:
       1. Reduce the quality of the tool, reduce the number of tool components, and simplify the tool structure
The comparison between the breaking limit of the different tool with the same diameter and the mass of the tool body, the number of tool components and the number of contact surfaces of the components is different. The comparison shows that the lighter the number of the tool, the fewer the number of components and the contact surface The higher the rupture limit, the higher the speed. The study found that the use of titanium alloy as a tool body material to reduce the quality of the tool can improve the fracture limit and limit speed. However, due to the sensitivity of titanium alloy on the incision, not suitable for the manufacture of knife body, so some high-speed milling cutter has been used high-strength aluminum alloy to create the body. In the structure of the blade, should pay attention to avoid and reduce the stress concentration, the body of the groove (including the knife slot, chip slot, keyway) will cause stress concentration, reduce the strength of the body, so should try to avoid the channel and Trough with sharp corners. At the same time, the structure of the blade body should be symmetrical to the rotary axis, so that the center of gravity through the milling cutter axis. Blade and knife seat clamping, adjust the structure should be as much as possible to eliminate the clearance, and requires a good repeatability. High-speed milling cutter has been widely used HSK tool holder and machine tool spindle connection, a greater extent to improve the tool system just and repeat the positioning accuracy, is conducive to the cutting speed limit of the tool. In addition, the diameter of the clip-type high-speed cutter shows a smaller diameter, the number of teeth to reduce the development trend, but also conducive to improve the strength and stiffness of the tool.
      2. Improve the clamping method of the tool
Simulation and rupture tests show that the high-speed milling cutter blade clamping method does not allow the use of the usual friction clamping, with a center hole with the blade, screw clamping, or with a specially designed tool structure to prevent the blade rejection fly. The direction of the clamping force of the tool holder and the blade is the same as that of the centrifugal force, and the preload of the screw is controlled to prevent the screw from being damaged in advance. For small diameter handle milling cutter, hydraulic chuck or thermal expansion and contraction chuck can be used to achieve high precision clamping and high stiffness.
        3. To improve the dynamic balance of the tool
Increasing the dynamic balance of the tool is of great help to improve the safety of the high speed milling cutter. Because the unbalanced amount of the tool produces an additional radial load on the spindle system, its size is proportional to the square of the speed. (N / 9549) 2 where: U is the tool system unbalance (g · mm), and the amount of eccentricity of the center of the center of the rotor is e, the inertial centrifugal force F caused by the unbalance is F = emω2 = (In millimeters), m is the tool system mass (kg), n is the tool system speed (rpm), ω is the tool system angular velocity (radians per second)
      As can be seen from the above, to improve the dynamic balance of the tool can significantly reduce the centrifugal force, improve the safety of high-speed tool. Therefore, in accordance with the requirements of the draft standard, for high-speed cutting of the milling cutter must undergo a dynamic balance test, and should be ISO1940-1 1 G4.0 balance above the required level of quality requirements.