Friction Stir Tool Current Control for Precise Plunging Force
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Solution Overview
Problem
Existing friction stir welding methods face challenges in accurately controlling the plunging depth of the tool due to discrepancies between the set and actual pressurizing forces, which can be attributed to factors like deflection of the C-frame and resistance during tool insertion, leading to potential misalignment and reduced welding quality.
Innovation Solution
A method and device that regulate the drive electric current to the friction stir tool based on a pressurizing force change ratio, allowing the actual pressurizing force to match the set force without the need for additional sensors, thereby ensuring precise control of the tool's plunging depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a loadcell is arranged at a position closer to the backup member to detect the actual pressurizing force, then the measurement precision of the pressurizing force is improved, but the device complexity and cost increase
Solution Approach 1:
The patent uses the robot arm's built-in force sensor to detect pressurizing force instead of adding a dedicated loadcell near the backup member. The robot arm's force sensor data is copied/used as the pressurizing force measurement, eliminating the need for additional sensors while maintaining measurement capability
Solution Approach 2:
The robot arm performs dual functions: it provides both the driving force for tool plunging and serves as the measurement device through its built-in force sensor. The system uses its own inherent capabilities (force sensor) to measure the pressurizing force it generates, eliminating the need for separate measurement equipment
2Manufacturing precision
If a loadcell is added to detect and feedback the actual pressurizing force, then the manufacturing precision of the plunging depth is improved, but the device complexity and cost increase
Solution Approach 1:
The patent copies the force measurement capability from the robot arm's built-in sensor to measure pressurizing force during plunging. This existing sensor data is reused for control purposes, avoiding the need to install and integrate additional loadcells and feedback control systems
Solution Approach 2:
The patent implements feedback control by using the robot arm's force sensor to detect actual pressurizing force and adjusting the plunging depth accordingly. The system compares the detected force with target values and automatically adjusts the tool position to maintain accurate plunging depth control
3Device complexity
If the set pressurizing force is used without considering actual pressurizing force variations, then the device complexity is reduced, but the manufacturing precision of the plunging depth deteriorates
Solution Approach 1:
The patent implements a feedback control mechanism where the robot arm's force sensor continuously monitors the actual pressurizing force during plunging. The system compares this feedback with the target pressurizing force and automatically adjusts the tool position to compensate for variations, maintaining accurate plunging depth without adding complex external measurement equipment
Solution Approach 2:
The robot arm's control system uses its own built-in force sensor data to self-regulate the plunging depth. The system automatically compensates for pressurizing force variations by adjusting its own operation based on real-time feedback from its inherent sensor, eliminating the need for external measurement and control equipment
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 reliable and sensorless control of the tool's plunging depth, maintaining consistent welding quality by adjusting the drive electric current to compensate for variations in pressurizing force, thus enhancing the accuracy and effectiveness of friction stir welding.
Implementation Method 1
a tool to be plunged into a workpiece while rotating at a high speed is used... perform friction stir welding
Implementation Method 2
The friction stir welding requires the tool to be plunged into the workpiece to reach a predetermined plunging depth and perform the friction stir welding there
Data Source
AI summary
A friction stir tool control method is a control method for controlling an operation of a friction stir tool by supplying a necessary drive electric current to a drive source of the tool. The control method includes obtaining a pressurizing force change ratio by comparing a set pressurizing force predefined as a pressurizing force at plunging of the tool into a workpiece with an actual pressurizing force occurring at actual plunging of the tool into the workpiece by supplying a drive electric current for generating the set pressurizing force to the drive source. The drive electric current is regulated in accordance with the pressurizing force change ratio so that the actual pressurizing force comes to the set pressurizing force, and the drive source is driven with the regulated drive electric current.