Through-Hole Depth Measurement Using Cutting Force Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for measuring through-hole depths in composite fiber reinforced plastic (CFRP) sheet material stacks are unable to accurately sense changes in drill force, particularly in pressure foot systems, leading to inaccuracies in fastener selection and hole depth determination.
Innovation Solution
A through-hole depth measurement device equipped with a cutting force sensor and a controller that senses cutting force between a drill spindle and spindle housing, and uses workpiece surface position sensors to determine the depth by detecting decaying force signals indicative of drill bit breakout, while distinguishing between breakout and peck cycle forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a pressure foot system driven by an air cylinder is used to exert constant pressure against the workpiece surface, then drilling stability is improved, but the ability to sense changes in drill force is lost
Solution Approach 1:
The pressure foot system is segmented into two independent functional components: a constant pressure generation system (air cylinder) and a variable force sensing system (load cell). This segmentation allows the pressure foot to maintain stable contact pressure while the load cell independently measures changes in drill force during drilling operations.
Solution Approach 2:
A load cell is introduced as an intermediary component between the pressure foot and the workpiece. This intermediary element transmits both the constant pressure force and the variable drill force, enabling the sensing system to detect drill force changes without interfering with the stable pressure application.
2Measurement precision
If individual hole depth measurements are made for each hole, then fastener selection accuracy is improved, but measurement time and productivity are reduced
Solution Approach 1:
The system performs hole depth measurements during the drilling operation itself, rather than as a separate subsequent step. The load cell continuously monitors drill force and detects breakout conditions, providing depth information in real-time as the drilling progresses, thereby eliminating the need for separate measurement steps.
Solution Approach 2:
The system implements real-time feedback through the load cell that continuously monitors drill force during the drilling process. When the drill bit breaks through the workpiece surface, the change in drill force is immediately detected and signaled, providing continuous depth information without interrupting the drilling operation.
3Loss of time
If drill force changes are not sensed accurately, then fastener bill of materials preparation is delayed, but inventory management efficiency is reduced
Solution Approach 1:
The load cell provides real-time feedback on drill force changes, enabling immediate detection of hole completion. This feedback mechanism allows the system to generate accurate hole depth information during drilling, which can be used to prepare fastener bills of materials without delay, improving both timing and accuracy.
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
Enables accurate and real-time measurement of hole depths during drilling, allowing for precise fastener selection and reducing the need for separate measurement steps, while accounting for workpiece deformation and displacement.
Implementation Method 1
A through-hole depth measurement device is provided for measuring the depth of a through-hole formed through one or more workpieces. The device may include a cutting force sensor configured and mountable in a position to sense cutting force exerted by a drill bit of a drill against a workpiece or stack of workpieces.
Data Source
AI summary
A through-hole depth measurement device includes a cutting force sensor configured and mountable in a position to sense cutting force exerted by a drill bit of a drill against a workpiece or stack of workpieces. A controller is coupled to the force sensor, is coupleable to a workpiece surface position sensor, and is configured to record the through-hole depth of the workpiece or stack of workpieces in response to signals received from the workpiece surface position sensor when the drill bit reaches a drill bit exit point. The cutting force sensor is configured and positionable to sense cutting force transmitted between a drill spindle and a spindle housing.