Hole Depth Determination via Tool Load Signal Analysis
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Solution Overview
Problem
In high-precision and safety-critical applications, such as aircraft components, accurately determining the depth of holes in multi-layered structures is challenging due to manufacturing tolerances, especially when using composite materials with varying fiber lay-ups, which can lead to inconsistent hole depths, necessitating precise measurement of hole depths for appropriate fixing means selection.
Innovation Solution
An automated method and device that determine hole depths during the hole-forming process using tool load signals, applying offset values based on material and tool properties, and calculating the hole depth by identifying a breakthrough threshold in the load signal to correct for variations, allowing for real-time or post-processing analysis to ensure accurate measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual measurement methods are used to determine hole depth, then measurement accuracy can be achieved, but measurement time and labor requirements increase significantly
Solution Approach 1:
The system performs hole depth measurement during the drilling process itself, before the drilling is completed. By monitoring the tool load signal in real-time during drilling and detecting the breakthrough point, the system determines hole depth proactively rather than requiring a separate post-drilling measurement step, thus eliminating time loss while maintaining accuracy
Solution Approach 2:
The drilling machine itself performs the measurement function by monitoring its own tool load signal during the drilling operation. The system uses the load data generated inherently during drilling to automatically determine when breakthrough occurs, making the measurement process self-service rather than requiring external measurement equipment or manual intervention
2Loss of time
If automated measurement during drilling is implemented, then measurement time is reduced, but measurement precision may be compromised due to process variations
Solution Approach 1:
The system continuously monitors the tool load signal during drilling and uses this feedback to detect the breakthrough point. By establishing a threshold value for the load signal and detecting when the signal crosses this threshold, the system accurately determines the moment of breakthrough, ensuring precise hole depth measurement despite process variations
Solution Approach 2:
The system monitors changes in the tool load parameter during drilling. The breakthrough point is detected by identifying when the load parameter crosses a predetermined threshold, transforming the continuous load signal into a discrete breakthrough detection event, thereby achieving precise measurement through parameter change detection
3Measurement precision
If hole depth measurement is performed separately after drilling, then measurement accuracy can be ensured, but productivity decreases due to additional operation steps
Solution Approach 1:
The system merges the hole depth measurement function with the drilling operation itself. By integrating the load signal monitoring and breakthrough detection into the drilling process, the measurement function is combined with the existing drilling machinery and operation, eliminating the need for separate measurement steps and thereby increasing productivity while maintaining measurement accuracy
Solution Approach 2:
The drilling machine is designed to perform multiple functions: it drills holes and simultaneously measures hole depth through load signal monitoring. This multi-functionality allows the same equipment to accomplish both material removal and dimensional measurement, eliminating the need for dedicated measurement equipment and operations, thus improving overall manufacturing efficiency
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
This approach enables precise and efficient measurement of hole depths during the drilling process, reducing manual measurement time and labor, ensuring accurate selection of fixing means and streamlining the assembly process by integrating depth determination into the drilling machine, thereby enhancing manufacturing efficiency and reducing errors.
Implementation Method 1
a tool load sensor arranged to detect a load on the tool during formation of the hole by the tool
Data Source
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AI summary
A method of determining a depth of a hole formed in a work piece is disclosed. The method includes determining the hole depth based upon a load signal indicative of a load on a tool forming the hole during the forming of the hole. The hole depth determined is then adjusted with an offset and component specifications are combined with the hole length to determine a component specification for use in the hole to fix components together. At least a part of the depth determination and component specification can be carried out automatically in a computer, for an array of holes.