Linear Friction Joining Load Control to Prevent Pressure Overshoot
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Solution Overview
Problem
Existing linear friction-joining devices face issues with overshooting of pressing load and surge pressure due to inertial forces when workpieces collide, potentially damaging the workpieces and precision instruments like servo valves.
Innovation Solution
A linear friction-joining device equipped with a controller that adjusts the joining load reaching time and gradually increases the pressing load, using sensors to manage the transition from position control to load control, preventing sharp increases in pressure and inertial forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If position control is changed to load control immediately after collision, then the pressing load can reach the joining load quickly, but the inertial force causes the pressing load to overshoot the joining load sharply
Solution Approach 1:
The controller performs preliminary action by detecting the collision between workpieces before the load control is fully activated, and prepares to adjust the pressing load increase rate in advance. This allows the system to prevent overshoot while maintaining quick response to reach the joining load.
2Measurement precision
If the cylinder displacement stops suddenly at the time of collision, then the position control is accurate, but a surge pressure occurs due to water hammer phenomenon
Solution Approach 1:
The controller provides beforehand cushioning by detecting the collision and immediately adjusting the pressing load increase rate to a lower value. This prevents the surge pressure that would otherwise occur due to the sudden stop of cylinder displacement, protecting the servo valve and hydraulic system from damage.
3Productivity
If the pressing load is increased rapidly to the joining load, then the joining process is efficient, but the workpiece may be damaged by exaggerated overshoot load
Solution Approach 1:
The system applies dynamics by making the pressing load increase rate adjustable rather than fixed. The controller dynamically changes the increase rate based on collision detection, allowing rapid load increase under normal conditions for efficiency, while reducing the rate when collision is detected to prevent workpiece damage.
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
Prevents overshooting of the pressing load and occurrence of surge pressure, ensuring safe and precise joining of workpieces by managing the inertial forces and pressure transitions during the joining process.
Implementation Method 1
a position sensor which is configured to measure a displacement amount of the second member in the pressing direction
Implementation Method 2
a load sensor which is configured to measure a pressing load of the second member pressed onto the first member
Implementation Method 3
when a surge pressure is generated by a so-called water hammer phenomenon in which a flowing fluid abruptly stops due to a sudden stop of a cylinder displacement at the time of the collision and a pressure in a path rapidly increases due to an inertial force of the fluid
Data Source
AI summary
The present disclosure provides a linear friction joining device which includes: a pressing device for pressing a second member onto a first member in a pressing direction; a vibrator for relatively vibrating the first member and the second member; a controller which is configured to bring the second member into contact with the first member by a position control, which depends on a measurement result of position sensors, to change the position control to a load control, which depends on a measurement result of load sensors, and to increase a pressing load toward a joining load; and a joining load reaching time adjuster which is configured to adjust a length of a joining load reaching time which is between the time when the position control is changed to the load control and the time when the pressing load reaches the joining load.