Piezo Electric Feed Rate Oscillator for Drilling Chip Control
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Solution Overview
Problem
Conventional drilling methods using positive feed tools generate long, spiral chips that are difficult to evacuate, leading to increased torque, longer cycle times, and poor hole quality, especially when drilling deep holes in hard materials, and current micro-peck drilling methods rely on expensive and short-lived oscillating thrust bearings.
Innovation Solution
A positive feed tool equipped with a piezo electric feed rate oscillator that allows for electronically controlled variable feed rate oscillation, enabling the chip formation to be controlled by adjusting the amplitude and frequency of the oscillation, thereby facilitating easier chip evacuation and optimizing drilling speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a constant feed rate is used during drilling, then the drilling process is simple and stable, but long spiral chips are generated that are difficult to evacuate
Solution Approach 1:
The patent applies periodic action by oscillating the feed rate between a maximum value and a minimum value during drilling. This periodic variation in feed rate causes the chip thickness to fluctuate, creating thin sections that act as natural break points, thereby dividing long chips into shorter segments that are easier to evacuate from the hole.
Solution Approach 2:
The patent implements dynamics by transitioning from a static constant feed rate to a dynamic oscillating feed rate. The feed rate is continuously adjusted during the drilling process, varying between maximum and minimum values to optimize chip formation and evacuation while maintaining drilling productivity.
2Productivity
If micro-peck drilling with oscillating thrust bearings is used, then chip evacuation is improved, but the thrust bearings are expensive and have limited life spans
Solution Approach 1:
The patent replaces the mechanical oscillating thrust bearing system with an electronic feed rate oscillation system. Instead of using mechanical components with limited lifespans, the invention uses electronic control to vary the feed rate, achieving the same chip breaking effect without the reliability issues of mechanical oscillating bearings.
Solution Approach 2:
The patent extracts the oscillation function from the mechanical thrust bearing and implements it through electronic feed rate control. This separates the chip breaking function from the mechanical support structure, eliminating the need for specialized oscillating thrust bearings and their associated reliability problems.
3Productivity
If the feed rate amplitude is increased to exceed the feed rate, then macro-peck drilling results with cutter removal from material, but cycle times increase
Solution Approach 1:
The patent applies partial action by using small amplitude oscillations around the mean feed rate rather than large amplitude oscillations that would completely remove the cutter from the material. This partial oscillation is sufficient to create chip break points while maintaining continuous cutting action and minimizing cycle time extensions.
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 piezo electric feed rate oscillator allows for controlled chip thickness and length, improving chip evacuation and drilling efficiency, reducing tool wear, and enabling higher drilling speeds without compromising component lifespan.
Implementation Method 1
piezo electric feed rate oscillator
Data Source
AI summary
A positive feed tool may include a motor, a power supply operably coupled to the motor to power the motor, a gear head and a spindle. The gear head may be operably coupled to the motor to be operated responsive to powering of the motor. The gear head may include a drive assembly and a feed assembly. The spindle may be operably coupled to the gear head to enable the spindle to be selectively driven rotationally and fed axially based on operation of the drive assembly and the feed assembly, respectively. The feed assembly may include an electronically controlled variable feed rate oscillator.