Composite Drilling Feed Control for Delamination and Burr Reduction
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Solution Overview
Problem
The manufacturing process of composite materials often results in delamination and burrs due to excessive drilling force, which compromises the lifespan and safety of materials used in industries like aerospace, where lightweight and high-strength composite materials are critical.
Innovation Solution
A drilling system that controls drilling force and feed speed using a combination of impedance control and proportional-integral-derivative (PID) force smoothing, and identifies the material type of the workpiece to adjust drilling parameters, converting between impedance and fixed force modes to minimize delamination and burrs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional drilling with constant high feed force is applied to composite materials, then drilling productivity is improved, but delamination and burrs occur reducing manufacturing precision
Solution Approach 1:
The patent implements dynamic control of feed force and feed speed throughout the drilling process. The system transitions between different drilling modes (approach, steady-state, and breakthrough phases) with continuously adjusted parameters. The feed force is dynamically reduced during approach and breakthrough phases, while maintaining appropriate force during steady-state drilling, thereby preventing delamination and burrs while maintaining productivity.
Solution Approach 2:
The patent changes multiple drilling parameters dynamically including feed force, feed speed, and spindle speed based on the drilling phase and detected material properties. The system adjusts these parameters in real-time based on feedback from force sensors and material identification, optimizing the balance between productivity and surface quality.
2Productivity
If high feed force is used to increase drilling productivity, then drilling speed is improved, but the drilling force stability deteriorates causing delamination
Solution Approach 1:
The patent employs feedback control through force sensors that continuously monitor the drilling force. The detected force information is fed back to the control system, which adjusts the feed force and feed speed in real-time to maintain stability. This closed-loop control prevents excessive force that would cause delamination while maintaining efficient drilling progress.
Solution Approach 2:
The system dynamically adjusts drilling parameters based on the detected drilling phase and material properties. During the approach phase, feed force is gradually increased; during steady-state drilling, force is maintained at optimal levels; and during breakthrough, force is reduced. This dynamic adaptation ensures force stability throughout the process while maintaining productivity.
3Device complexity
If fixed drilling parameters are used for all material types, then device complexity is reduced, but adaptability to different material types deteriorates
Solution Approach 1:
The patent implements self-service through automated material identification and parameter selection. The system uses sensors to detect material properties and automatically selects appropriate drilling parameters without requiring manual intervention or complex pre-programming for each material type. This maintains relative system simplicity while achieving high adaptability to different composite materials.
Solution Approach 2:
The system automatically changes drilling parameters based on detected material type and properties. Different material types trigger different parameter sets for feed force, feed speed, and spindle speed. This automated parameter adaptation provides versatility across material types while keeping the control system relatively simple through rule-based or AI-driven parameter selection.
4Productivity
If rapid feed speed is used to improve productivity, then drilling efficiency is improved, but feed impact increases causing delamination
Solution Approach 1:
The patent applies periodic variation in feed speed corresponding to the drilling phases. The system uses a multi-phase drilling approach where feed speed is high during steady-state drilling but reduced during approach and breakthrough phases. This periodic modulation of feed speed maintains high overall efficiency while minimizing impact forces that cause delamination.
Solution Approach 2:
The system dynamically adjusts feed speed based on the detected drilling phase and material properties. Feed speed is optimized for each phase: moderate during approach to minimize impact, high during steady-state for maximum efficiency, and reduced during breakthrough to prevent delamination. This dynamic control resolves the contradiction between productivity and harm reduction.
Data Source
AI summary
A drilling system including a feed control module, a force control module, a hole breaking control module, a conversion module and a computing unit is provided. The feed control module sets a feed force threshold and a feed speed threshold for the computing unit to determine whether the current mode satisfies a first conversion condition. The hole breaking control module sets a drilling penetration force threshold and a drilling penetration speed threshold for the computing unit to determine whether the current mode satisfies a second conversion condition. The conversion module informs to change the feed force and the feed speed according to the determination results of the two conversion conditions. The force control module provides the feed force. With the drilling system, possible impact on the workpiece due to resistance change which occurs when the drill just touches and nearly gets through the workpiece will be reduced.