The Cause Analysis of Machining Tool Vibration And Prevention

machining tool vibration analysis and prevention

Machine tool processing vibration resulting in workpiece surface chatter, rework rate, scrap rate is high. Machine vibration is generally the cause of machine tool - workpiece - tool in any one of the three systems or more system rigidity is insufficient, the following first vibration, vibration knife generated by the need to start from what aspects of the investigation.

1. Workpiece aspects of the investigation points

(1) long and thin shaft cylindrical turning; general cutting point from the distance of the clamping point, if the length to diameter ratio of more than 3, then it is easy to vibrate the knife, you can consider changing the process.

(2) External turning of thin-walled parts.

(3) Box-shaped parts (such as sheet metal welding structure) turning.

(4) Cutting of super-hard materials.

2. Reasons for cutting tools

(1) Forming turning with forming inserts;

(2) Angle of the tool especially main offset angle, back angle, front angle, etc;

(3) Sharpness of the cutting edge;

(4) Whether the radius of the tip circle is too large;

(5) Whether the cutting parameters are appropriate.

3. machine causes

(1) The live center extends too long

(2) bearing has been damaged and continue cutting

First check the rigidity of the tool itself, whether it is not clamped? Is it too long? Is the shim uneven? Then check the turning tool (boring tool) is worn? Whether the tip of the rounded corner or trimming edge is too wide? Is the back angle of the cutter too small? Look at whether you are using a 90-degree tool or a 45-degree tool, and try to change it. In addition, go knife (feed) is too small, may also be a cause of chatter, can be slightly adjusted to increase a little. Adjust the speed, single knife depth of cut, feed to try to rule out the resonance point.

Exhaustion of machine tools and mounting parts of the cause

(1) Find out whether your live center is too long, bearing is not good. Inside the plane rolling bearing combination. Really doubt, you can use the dead top replacement, pay attention to the center hole of the butter lubrication.

(2) Find out your tailstock top clamping situation, clamping conditions are not left and right in, up and down in and machine tool spindle is not centered.

(3) the large and small drag plate are tightened some, especially in the drag plate.

(4) If it is the tailstock part of the machine you can not go to check for the time being (points 1 and 2, you need some clamping foundation), you can try to go from the end of the card grip to the tail. Reverse turning will maximize the chipping of the tailstock end's lack of give.

(5) If there is still a situation in step 4, you have to look at the spindle, and of course, if it is a three-grip, you have to check if there is damage to the spiral groove. The four grasps are manually self-supporting adjustment, there is no need to check.

Comprehensive suppression of vibration knife countermeasures

If your main shaft tile has been really tightened in place, the workpiece is not a thin-walled hollow parts or overhang too long, the chuck clamping is no problem. Adopt some other countermeasures to suppress tool vibration. According to the principle of vibration knife research, currently applied to the machining site there are some specific and practical methods:

(1) Reduce the working weight of the part causing vibration, the smaller the inertia, the better.

(2) For the vibration of the largest place to be fixed or clamped, such as the center frame, work holding device.

(3) Improve the rigidity of the machining system, such as the use of a higher coefficient of elasticity of the shank or the use of a special vibration-resistant force added to the Dynamic Damper (Dynamic Damper) to absorb the impact energy.

(4) Work from the blade and work rotation direction.

(5) Change the appearance of the tool and the angle of entry, Nose Radius , the smaller the better, in order to reduce cutting resistance. Sick Rake Angle must take a positive value, so that the cutting direction more nearly vertical. Back Rake Augle is the best positive value, but even the ability to remove chips is relatively poor, so you can generally use the fluted cutter to make the angle of inclination into a negative value, but still retain a positive value of the cutting effect.