Linear Friction Joining Load Control to Prevent Overshoot
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Solution Overview
Problem
The existing linear friction-joining devices face issues with overshooting of pressing load and surge pressure due to inertial forces when workpieces collide, which can damage the workpieces and precision instruments like servo valves.
Innovation Solution
A controller, acting as a joining load reaching time adjuster, adjusts the length of time it takes to reach the joining load by gradually increasing the pressing load, preventing the inertial force from causing a sharp increase in load during the collision, and a spring member can be used to mechanically implement this adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If position control is used to bring workpiece B into contact with workpiece A, then the workpieces can be joined by linear friction welding, but the inertial force of the heavy jig causes the pressing load to overshoot the joining load sharply
Solution Approach 1:
The controller performs preliminary action by switching from position control to load control before the workpiece collision is complete. This allows the pressing load to be regulated in advance, preventing the inertial force from causing a sharp overshoot of the joining load. The load control is activated when the pressing load reaches a predetermined threshold, ensuring smooth transition and avoiding damage to workpieces and precision instruments.
2Speed
If the cylinder displacement is suddenly stopped at the time of collision, then the workpiece B can be brought into contact with workpiece A, but a surge pressure is generated in the hydraulic path due to water hammer phenomenon
Solution Approach 1:
The system applies dynamics by transitioning from rigid position control to flexible load control during the collision process. The load control mechanism allows the pressing load to be regulated dynamically, preventing sudden stops of cylinder displacement. This dynamic adjustment avoids the water hammer phenomenon and surge pressure generation in the hydraulic path, protecting servo valves and other precision instruments from damage.
3Measurement precision
If the workpiece B is mounted on a heavy jig for position control, then the workpiece can be accurately positioned, but the inertial force of the jig causes overshooting of the pressing load
Solution Approach 1:
The controller acts as an intermediary between the position control system and the load control system. It monitors the pressing load and automatically switches from position control to load control when the load reaches a predetermined threshold. This intermediary function mediates the conflict between the heavy jig's position control accuracy and its inertial force, ensuring smooth transition and preventing pressing load overshoot.
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 effectively prevents overshooting of the pressing load and occurrence of surge pressure, ensuring safe and precise joining of workpieces by managing the inertial forces during the collision process.
Implementation Method 1
the joining load reaching time adjuster is a spring member interposed between the jig and the cylinder device
Implementation Method 2
a pressing device which presses the workpiece B onto the workpiece A
Implementation Method 3
a vibration device which vibrates the workpiece A in a direction parallel to a bonding surface
Implementation Method 4
linear friction welding (LFW)
Data Source
Figure 1
Figure 2~2(d)
Figure 3~3(d)
AI summary
The present disclosure provides a linear friction-joining device (1) which includes: a pressing device (10) for pressing a second member (B) onto a first member (A) in a pressing direction; a vibrator (20) for relatively vibrating the first member (A) and the second member (B); a controller (40) which is configured to bring the second member (B) into contact with the first member (A) by a position control, which depends on a measurement result of position sensors (30 and 31), to change the position control to a load control, which depends on a measurement result of load sensors (32, 320, and 321), and to increase a pressing load toward a joining load; and a joining load reaching time adjuster (40, 42, 43, and 60) which is configured to adjust a length of a joining load reaching time (t) 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.