Oscillating Thrust Bearing for 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 hard materials like steel and titanium, due to constant feed rates.
Innovation Solution
A positive feed tool employing a feed rate oscillator with a dual cam structure and rolling elements that alternate between loaded and unloaded states, creating oscillating feed rates to control chip formation and extend the life of the rolling elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a constant feed rate is used in drilling operations, then the drilling process is simple and continuous, but long spiral chips are generated that are difficult to evacuate, leading to increased torque and longer cycle times
Solution Approach 1:
The patent applies periodic action by oscillating the feed rate between a maximum value and a minimum value during the drilling operation. This causes the chip thickness to vary periodically, breaking the continuous spiral chip formation into shorter segments that can be evacuated more easily from the hole, thereby resolving the chip evacuation difficulty while maintaining drilling efficiency
Solution Approach 2:
The patent transitions from a static constant feed rate to a dynamic oscillating feed rate. The feed rate is continuously varied between maximum and minimum values during drilling, allowing the system to adapt chip thickness in real-time to facilitate chip evacuation while maintaining productive drilling operation
2Object-generated harmful factors
If special thrust bearings with oscillating cam profiles are used to achieve micro-peck drilling, then chip evacuation is improved, but the bearings become very expensive and have limited life spans
Solution Approach 1:
The patent replaces expensive special thrust bearings with standard off-the-shelf thrust bearings combined with a cam mechanism. This substitution uses cheaper, more readily available components that can be easily replaced if needed, significantly reducing cost while achieving the same oscillating feed rate effect for improved chip evacuation
Solution Approach 2:
The patent separates the oscillating feed rate function from the thrust bearing itself. Instead of requiring a complex oscillating cam profile integrated into the thrust bearing, the invention uses a separate cam mechanism that works with a standard thrust bearing, dividing the function into simpler, more reliable components
3Object-generated harmful factors
If the feed rate is varied to break chips, then chip evacuation is improved, but the drilling process becomes more complex
Solution Approach 1:
The patent introduces a cam mechanism as an intermediary between the motor and the feed system. This cam translates the continuous rotation from the motor into the desired oscillating feed rate motion, providing a simple mechanical solution that avoids complex electronic control systems while achieving effective chip breaking through feed rate variation
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 oscillating feed rate effectively breaks and evacuates chips more easily, improving drilling efficiency and reducing component wear, while extending the life of the rolling elements.
Implementation Method 1
The rolling elements alternate between a first state in which at least some of the rolling elements are unloaded and a second state in which all of the rolling elements are loaded
Data Source
AI summary
A positive feed tool may include a motor, a gear head and a spindle. The gear head may be operably coupled to the motor and may include a drive assembly and a feed assembly. The spindle may be operably coupled to the gear head and may be selectively driven rotationally and fed axially based on operation of the drive assembly and the feed assembly, respectively. The feed assembly may include a feed rate oscillator having a fixed cam and a movable cam operably coupled to each other via a plurality of rolling elements to oscillate between a maximum width and a minimum width of the feed rate oscillator based on a position of the movable cam. The rolling elements alternate between a first state in which at least some of the rolling elements are unloaded and a second state in which all of the rolling elements are loaded.