Some solutions to the problem of lathe vibration and cutter flutter
Machine vibration and cutter flutter will result in work-piece surface chatter, high rate of rework, reject rate.The reason for machine tool vibration is generally the machine, work-piece, cutting tool in any one or more of the three systems of rigidity is insufficient, the following is the start of problem solving.
1. Work-piece aspect
(1) the outer circle turning of slender shafts; General cutting point from the distance of the clamping point, if the aspect ratio is more than 3, it is easy to vibrate the knife, you can consider changing the process;
(2) the outer circle turning of thin-walled parts;
(3) box-shaped parts (such as sheet metal welding structural parts) turning;
(4) super hard material cutting.
2. Cutting tool aspect
(1) using the forming blade for forming turning;
(2) the tool's Angle, especially the main Angle, back Angle, front Angle, etc.;
(3) the sharpness of the blade;
(4) Whether the radius of the tool tip arc is too large;
(5) Whether the cutting parameters are appropriate.
3. Machine aspect
(1) the living tip extends too long;
(2) the bearing has been damaged and continues to cut
Check if it’s related to the cutter
First check the turning tool itself stiffness, whether it is not clamped? Is it stretching out too long? Are gaskets uneven? Check again whether the turning tool (boring tool) is worn? Is the tip rounded or the trimming edge too wide? Is the back Angle of turning tool too small? Check whether you're using a 90-degree knife or a 45-degree knife, and try switching.In addition, the knife (feed) is too small, may also be a cause of chatter, can be slightly adjusted to increase a little.You adjust the speed, depth of single tool cutting, feed to try to eliminate the resonance point.
Check the machine and clamping status
(1) check for your live top is not extended too long, the bearing is not good. Inside is a plane rolling bearing assembly. Or we can use the dead top for testing.
(2) check for your tail frame top clamping situation, clamping conditions are not around, up and down and different from the spindle of the machine tool.
(3) the large, medium and small towing plate are tight, especially in the towing plate.
(4) if it is the tail-frame part of the machine tool that you cannot check for the time being (point 1 and 2, some bench working experience is needed), you can try to move the cutter from the clamping end to the tail. Anti-turning can eliminate the rear end of the force to the greatest extent.
(5) if there is a situation in the fourth step, to look at the spindle, of course, if the three grasp, also want to check, whether the spiral groove is damaged.Four grasp is manually supported and adjusted, there is no need to check.
Countermeasure of synthetically restraining vibration
If your spindle tile is really tight in place, and the work-piece is not thin-walled hollow or overhung, the chuck clamping is fine.Adopt some other countermeasure to restrain cutter flutter. According to the principle of shaking knife obtained from the research, there are some specific and practical methods applied in the processing site at present:
(1) reduce the working weight of the part causing vibration, the less inertia the better;
(2) for the vibration of the largest place to be fixed or clamped, such as the center frame, working retainer, etc.;
(3) to improve the rigidity of the processing system, such as the use of a higher coefficient of elasticity of the tool handle or the use of a special seismic force added to the Dynamic Damper to absorb impact energy;
(4) from the blade and the direction of working rotation;
(5) change the appearance and Angle of the tool, the smaller the Nose Radius of the tool, the better, in order to reduce cutting resistance.The Sick Rake Angle must be positive to make the cutting direction more vertical.The Back Rake Augle is best to be positive, but even the chip removal ability is relatively poor, so the general choice of slot knife to make the Angle of negative, but still maintain a positive cutting effect.
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