Rail Welding Head Jerk Compensation Control
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Solution Overview
Problem
Existing flash butt welding systems for railway rails face challenges in maintaining consistent weld quality due to varying field conditions, as feedback control based on welding current is not always sufficient to account for rapidly changing conditions, leading to issues like rail jerk and current shunting, which can result in poor weld quality and instability.
Innovation Solution
A welding head with a controller and closing actuator system that monitors the closing force and adjusts the movement of rail segments to maintain a predetermined current, actively compensating for rail jerk by decreasing the closing force when a threshold rate of change is detected, and ensuring consistent weld quality by controlling the closing velocity and preventing bridging between the rails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If feedback control based on welding current is used to control rail closing speed, then weld quality can be maintained under normal conditions, but the system becomes unstable and exhibits rate oscillations when subjected to rapidly changing field conditions
Solution Approach 1:
The patent implements feedback control by monitoring welding current and adjusting rail closing speed accordingly. When current exceeds target values, the system reduces closing speed; when current is below target, it increases closing speed. This closed-loop feedback mechanism maintains weld quality despite varying field conditions.
Solution Approach 2:
The control system dynamically adjusts the rail closing speed based on real-time current measurements and changing field conditions. The system transitions from static predetermined speeds to dynamic adaptive control, allowing it to respond to rapidly changing conditions while maintaining stability through controlled adjustment rates.
2Productivity
If the rail segments are moved together too quickly during welding, then productivity increases, but the weld quality deteriorates due to low temperature and homogeneity issues
Solution Approach 1:
The system uses welding current as a feedback signal to determine optimal closing speed. Higher current values indicate that rails can be moved faster while maintaining adequate heating, allowing the system to maximize productivity without sacrificing weld quality.
Solution Approach 2:
The control system changes the closing speed parameter dynamically based on measured current values. As current increases during the welding process, the system permits higher closing speeds, optimizing the balance between productivity and weld quality throughout the welding cycle.
3Manufacturing precision
If the rail segments are moved together too slowly during welding, then weld quality is maintained, but productivity decreases and heated surfaces oxidize
Solution Approach 1:
The feedback control system prevents excessively slow closing speeds by monitoring current levels. When current indicates sufficient heating rate, the system increases speed to maintain productivity while preventing oxidation. This ensures speeds remain within the optimal range for both quality and efficiency.
Solution Approach 2:
The system applies preliminary control actions to prevent oxidation by maintaining minimum closing speeds. The control algorithm anticipates oxidation risks and adjusts speeds proactively to keep heated surfaces within the protective atmosphere window, balancing quality protection with productivity requirements.
4Stability of the object's composition
If limits are placed on control output changes to prevent instability, then system stability is maintained, but the system cannot respond rapidly to changing field conditions
Solution Approach 1:
The system implements dynamic control output adjustment with adaptive rate limiting. While limits are placed on control output changes to prevent instability, the system dynamically adjusts these limits based on current welding conditions, allowing faster response when conditions permit and slower response when stability is at risk.
Solution Approach 2:
The control system applies beforehand cushioning by implementing progressive control output changes rather than abrupt adjustments. This prevents instability by cushioning extreme control actions while still allowing adequate response to field conditions through controlled, progressive adjustments that respect system stability constraints.
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
The system effectively maintains consistent weld quality across varying field conditions by actively managing rail jerk and bridging, ensuring that the welding current remains close to a predetermined value, thereby preventing defects and maintaining the integrity of the weld.
Implementation Method 1
a current is passed between them... when the first rail segment and the second rail segment approach one another
Implementation Method 2
If the controller determines that the closing force has changed faster than a threshold rate of change, thereby indicating an impending rail movement jerk, it actuates the closing actuator to decrease the closing force
Implementation Method 3
During flash butt welding, the two rails ends to be joined are first heated and then forged together, expelling liquid metal and oxides from the weld joint
Data Source
AI summary
An improved welding head for creating an in-track weld between a first rail segment and a second rail segment includes a controller having computer-readable instructions read by the controller. The computer-readable instructions include instructions for compensating for rail jerk during in-track welding. The welding head includes a closing force actuator, such as a hydraulic cylinder, for moving the rail segments toward one another. A pressure transducer is monitored during welding to determine a closing force. An impending jerk of the rail movement is detected if an abnormal closing force change is observed, and in response the flow of hydraulic fluid into or out of the hydraulic cylinder is restricted to prevent or minimize the jerk. In addition, when an impending jerk is detected the weld current may be temporarily increased to burn or prevent the formation of short circuit paths between the rails.