Helical Rotary Cutting Tool With Tuned Vibration Absorber
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Solution Overview
Problem
Rotating cutting tools, such as solid carbide end mills, experience undesirable vibrations during operation, leading to poor workpiece surface finish, out-of-tolerance finished workpieces, and potential tool damage.
Innovation Solution
A tunable vibration absorber is integrated into the rotary cutting tool, featuring an absorber mass and a resilient material within an internal cavity that follows the twisted helical shape of the tool's flutes. The absorber's length and mechanical properties are tuned to match the natural frequency of the drill body, causing destructive interference and reducing vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional solid end mill is used for slotting operations, then material can be removed in both axial and radial directions, but torsional vibrations occur at high frequencies causing chatter and poor surface finish
Solution Approach 1:
The patent converts the harmful high-frequency torsional vibrations into a beneficial effect by introducing a tuned mass damper that generates destructive interference. The damper's natural frequency is tuned to match the tool's critical frequency, causing the absorber mass to vibrate out of phase with the tool body, thereby canceling the harmful vibrations and improving surface finish quality
2Length of moving object
If the length of the rotary cutting tool is increased to achieve large L/D ratios, then deeper cuts become possible, but torsional vibrations and chatter are exacerbated
Solution Approach 1:
The patent changes the dynamic parameters of the tool system by adding a tuned mass damper with specific mass, stiffness, and damping characteristics. The damper's natural frequency is carefully tuned to match the critical frequency of the extended tool, and its mass ratio is optimized to effectively suppress vibrations. This parameter adjustment allows the tool to maintain stability despite increased length and higher L/D ratios
3Productivity
If modular drills with large diameters are used for heavy duty operations, then material removal rate increases, but self-excited vibrations and noise are generated
Solution Approach 1:
The patent introduces a tuned mass damper as an intermediary element between the tool body and the cutting edges. This damper acts as a mediator that absorbs and dissipates the self-excited vibrations generated during heavy duty operations. The damper's resilient material and absorber mass work together to isolate the harmful vibrations from the tool body, reducing noise and improving operational stability while maintaining high material removal rates
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The implementation of the tunable vibration absorber significantly suppresses or eliminates torsional and axial vibrations in the rotary cutting tool, enhancing the cutting process stability and reducing the risk of tool damage.
Implementation Method 1
a resilient material disposed between the absorber mass and an outer wall of the internal cavity
Implementation Method 2
the frequency of the tunable vibration absorber causes destructive interference between the tunable vibration absorber and the natural frequency of the end mill, thereby reducing or eliminating vibration
Implementation Method 3
an absorber mass disposed within an internal cavity that follows the twisted helical shape of the flutes in the rotary cutting tool
Data Source
AI summary
A rotary cutting tool includes a tool body including a shank portion and a cutting portion adjoining the shank portion. The cutting portion has a plurality of blades separated by helically twisted flutes. A tunable vibration absorber is disposed within an internal cavity formed in the cutting portion and has a shape that follows the helically twisted flutes. The tunable vibration absorber includes an absorber mass and a resilient material disposed between the absorber mass and an outer wall of the internal cavity. In one aspect, the tunable vibration absorber is tuned to a desired frequency by selecting the mechanical properties of the absorber mass and the resilient material. In another aspect, the tunable vibration absorber is tuned by controlling a pressure of fluid within a main internal fluid cavity disposed within the tunable vibration absorber.