Impact-Based Interference Fit Assembly Process Control
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Solution Overview
Problem
Existing methods for achieving an interference fit, such as iterative press-in processes, face challenges in dimensional accuracy and efficiency due to elastic behavior of components, leading to increased static friction and the risk of overshooting the desired stroke, which complicates process control and can result in reduced component strength and increased production costs.
Innovation Solution
The method employs a series of short, mechanically generated impacts to overcome static friction and achieve a defined feed, with the impact energy dimensioned to overcome sliding friction, allowing for precise control and increased dimensional accuracy by avoiding quasi-static elastic deformations. This is facilitated by an impact generator and a control device that adjusts pulse energy based on press-in progress and speed, using a force sensor to measure and regulate the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an iterative press-in process is used to achieve dimensional accuracy, then the desired stroke can be approached, but the process time increases significantly and the risk of overshooting remains
Solution Approach 1:
The patent applies periodic impact forces instead of continuous quasi-static pressing. The press-in process uses a series of controlled impact pulses that periodically apply force to the component, enabling rapid advancement through the press-in stroke while maintaining precision. This periodic action eliminates the need for multiple iterative slow-press cycles, dramatically reducing process time while avoiding overshooting through controlled pulse delivery.
Solution Approach 2:
The patent replaces the traditional quasi-static mechanical pressing system with an impact-based mechanical system. Instead of applying continuous gradual force through a press mechanism, the invention uses controlled impact forces delivered through an impact generator, substituting the slow iterative mechanical pressing approach with a faster impact-driven process that achieves the same dimensional accuracy without the time penalty.
2Force
If higher press-in forces are applied to overcome static friction, then the pressing-in process can advance, but elastic compression increases causing expansion and increased static friction that complicates control
Solution Approach 1:
The patent uses periodic impact forces that apply high press-in force only during the brief impact duration, then allow the force to drop to zero between impacts. This periodic application of force overcomes static friction at the moment of impact when needed, while avoiding sustained high forces that would cause elastic compression and expansion. The component can relax between impacts, maintaining dimensional stability and simplifying control.
Solution Approach 2:
The patent transitions from a static or quasi-static force application system to a dynamic impact-based system. The press-in force becomes time-dependent, varying rapidly between zero and high values during each impact cycle. This dynamic force application allows the system to overcome static friction thresholds momentarily while avoiding sustained compression that would cause elastic expansion and control difficulties.
3Manufacturing precision
If multiple iterations are performed to achieve desired tolerance, then dimensional accuracy improves, but component strength decreases due to repeated stress loading
Solution Approach 1:
The patent uses a single pass of periodic impacts instead of multiple iterative pressing cycles. The component experiences one series of controlled impact pulses that achieve the full press-in stroke and desired tolerance in one operation, rather than repeated loading cycles. This eliminates cumulative stress damage while maintaining precision, as the component is not repeatedly loaded and unloaded through multiple iteration cycles.
Solution Approach 2:
The patent replaces the iterative quasi-static pressing system with a single-pass impact system. Instead of applying gradual force repeatedly over multiple cycles, the invention uses a series of controlled impacts in one operation to achieve the same dimensional result. This substitution eliminates the repeated stress loading inherent in iterative processes, preserving component strength while achieving the required tolerance range.
4Reliability
If the press-in drive is given a smaller travel path to prevent overshooting, then component usability is maintained, but the number of iterations increases
Solution Approach 1:
The patent incorporates feedback control where the actual press-in position is monitored during the impact process, and subsequent impact parameters are adjusted based on this feedback. This allows the system to approach the target position accurately without overshooting, while still using larger effective travel paths in each impact cycle. The feedback mechanism enables single-pass or minimal-iteration operation by continuously adjusting the impact parameters based on real-time position information.
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 significantly simplifies process control, enhances dimensional accuracy, and reduces the risk of overshooting, enabling faster and more precise assembly with improved component quality and reduced production time.
Implementation Method 1
at least part of the force curve is generated by a large number of automatically generated and controlled impacts which act on at least one of the parts and which are generated by an impact generator
Implementation Method 2
the reason for the limitations of the iterative method mentioned above can lie in the elastic behavior exhibited by the components to be joined. On the one hand, it was recognized that the press-in force can cause elastic compression in the axial direction, which is accompanied by an expansion of the component to be pressed in in the transverse direction and/or an increase in the transverse forces, i.e. the forces acting on the friction surfaces
Implementation Method 3
The sliding friction force, on the other hand, is usually less affected by the compression
Data Source
Figure 1~2
Figure 3
AI summary
The method involves pressing a unit (1) by applying an axially directed force phase in a recess into another unit (2). A portion of the force phase is produced by multiple automatically generated and controlled impacts, which works on the units and which are generated by a surge generator (20). An independent claim is also included for a device for adding or working on interference fit assembly.