Friction Welding Current Limiting for Torque Load Control
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Solution Overview
Problem
Friction joining processes in machine tools face issues with failure occurrence and inaccurate quality determination due to large torque loads and difficulties in detecting abnormalities, particularly when joining workpieces with high-speed rotation.
Innovation Solution
A friction joining device with current limiting means to control the current flowing to drive sources, limiting it to predetermined values during specific periods of the friction heating process to prevent excessive torque loads and improve quality determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed rotation is used for friction joining, then joining efficiency is improved, but large torque loads cause failures and device disorders
Solution Approach 1:
The patent applies dynamic control by varying the current limit value throughout the friction joining process. During the initial contact phase, a first current limit value is applied, and during subsequent phases, a second current limit value is applied. This dynamic adjustment allows the system to maintain high rotation speeds for efficiency while preventing excessive torque loads that cause failures, thereby resolving the contradiction between productivity and reliability.
2Reliability
If current limiting is applied during friction heating, then failure occurrence is suppressed, but joining efficiency may be reduced
Solution Approach 1:
The patent implements periodic action by dividing the friction joining process into distinct phases with different current limit values. The first current limit value is applied during the initial friction heating period, and the second current limit value is applied during subsequent periods. This periodic control strategy suppresses failures during critical phases while maintaining efficiency during stable phases, resolving the contradiction between reliability and productivity.
3Measurement precision
If power monitoring is used for quality determination, then some abnormalities can be detected, but detection accuracy remains insufficient
Solution Approach 1:
The patent applies feedback control by continuously monitoring the current consumed by drive sources and comparing it against predetermined current limit values. The control unit adjusts the current limits based on feedback from the monitoring unit, enabling accurate detection of abnormalities during friction joining. This feedback mechanism significantly improves quality determination accuracy compared to conventional power monitoring methods.
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
Suppresses failure occurrence and enhances the accuracy of quality determination in friction joining by controlling current flow to drive mechanisms, ensuring stable and reliable joining of workpieces.
Implementation Method 1
a first workpiece (a new bar material used for a next step) gripped by a spindle (first spindle) and a second workpiece (a remaining material remaining from a previous step) gripped by a rear face spindle (second spindle) are relatively rotated. Then opposing end faces of the first workpiece and the second workpiece are contacted with each other by decreasing the distance between the spindles in the axial direction, so that frictional heat is generated in the sliding portions.
Implementation Method 2
frictional heat is generated in the sliding portions. Once the joined portion is sufficiently softened by friction, the relative rotation between the spindles is stopped while maintaining the applied pressure.
Data Source
Figure 1
Figure 2(a)~2(d)
Figure 3
AI summary
Provided is a technique capable of suppressing occurrence of failure in friction welding and improving accuracy of quality determination of a joint state. Provided is a friction welding device that joins a first workpiece and a second workpiece by bringing the first workpiece and the second workpiece into contact with each other in a state in which the workpieces are rotated relative to each other, wherein, in a first friction heating period that is a predetermined period immediately after the first workpiece and the second workpiece come in contact with each other, an electric current that flows to a first drive source of a first drive mechanism that moves a first spindle for gripping the first workpiece in the axial direction, and a second drive source of a second drive mechanism that moves a second spindle that grips the second workpiece in the axial direction is limited to a first limit value or less that is smaller than a second limit value for limiting the electric current flowing to the first drive source and the second drive source in a second friction heating period after the first friction heating period has elapse.