Crankshaft Transition Radius Impact Hardening With Position Locking
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Solution Overview
Problem
Current methods for impact hardening crankshafts, such as those described in DE 34 38 742 C2 and EP 1 716 260 B1, are complex and expensive due to the need for intricate components like gears and clutches to prevent damage during forced stops and ensure synchronized clocking of the crankshaft, which complicates the introduction of residual compressive stresses.
Innovation Solution
A method and device that utilize a locking device to secure the crankshaft in an impact position, allowing for precise application of an impact force along transition radii without stopping the rotational movement, thereby avoiding shear stresses and simplifying the mechanical components required, using a drive device and impact tool synchronized for targeted impact hardening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the crankshaft is continuously rotated during impact hardening, then productivity is improved, but complex mechanical components (gearboxes, couplings, spring systems) are required to prevent damage from forced stops
Solution Approach 1:
The patent replaces the mechanical stopping mechanism (gearboxes, couplings, spring systems) with a controlled interruption of power supply to the drive motor. The crankshaft is rotated continuously by the motor, and impact forces are applied during rotation. When an impact is needed, the motor is simply switched off, allowing the crankshaft to coast to a stop through friction and air resistance, eliminating complex mechanical stopping components.
Solution Approach 2:
The patent extracts and removes the complex mechanical components (gearboxes, couplings, spring systems) that were previously necessary for forced stopping. By using electric motor control instead, these mechanical elements are completely eliminated from the drive system, simplifying the overall device architecture.
2Manufacturing precision
If complex mechanical components are used to ensure synchronized clocking, then manufacturing precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces mechanical synchronization components with electronic control of the drive motor. The motor's rotational position and speed are controlled electronically through programmable logic, allowing precise timing of impact forces relative to crankshaft position without requiring mechanical linkages, gears, or specialized synchronization mechanisms.
Solution Approach 2:
The patent implements a control system that monitors the crankshaft's rotational position and uses this feedback to precisely time the application of impact forces. Sensors detect crankshaft position, and the control unit processes this information to trigger impacts at the correct moments, ensuring synchronized clocking through electronic feedback rather than mechanical means.
3Strength
If the crankshaft is stopped during impact, then shear stresses are avoided, but productivity decreases and complex stopping mechanisms are required
Solution Approach 1:
The patent applies impact forces periodically during the crankshaft's rotation cycle. The motor rotates the crankshaft continuously, and impact forces are applied at specific intervals when the crankshaft passes through predetermined positions. This periodic application of impacts during rotation maintains productivity while achieving the necessary residual compressive stresses for improved fatigue strength.
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 enhances the fatigue strength of crankshafts by introducing residual compressive stresses with high precision, reducing the complexity and cost of mechanical components, and allowing for the use of direct drives without clutches, thus improving the reliability and efficiency of the impact hardening process.
Implementation Method 1
The increase in fatigue strength is achieved by introducing impact forces into the stressed areas of the crankshaft at cross-sectional transitions and changes through cold forming, preferably hammering with special impact tools.
Implementation Method 2
a striking tool (16) for introducing a striking force (F) into at least one transition radius (8) of the crankshaft (4)
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a method for the impact treatment of transition radii (8) of a crankshaft (4, 4'), in particular transition radii (8) between connecting rod bearing journals (5, 5') and crank webs (7, 7') and/or transition radii (8) between main bearing journals (6, 6') and the crank webs (7, 7') of the crankshaft (4, 4'). The crankshaft (4, 4') is then rotated along a rotational direction into an impact position by means of a drive device (3, 3'). A locking device (12) is provided in order to lock the crankshaft (4, 4') in the impact position, and an impact force is then introduced into at least one transition radius (8) by at least one impact tool (16, 16').