Fracture-Split Connecting Rod Coating Stress Compensation
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Solution Overview
Problem
Existing methods for producing fracture-split components, such as connecting rods, with low-melting bearing materials induce internal tensile stresses, leading to distortion and requiring straightening or assembly aids for precise reassembly, while high-melting materials also cause stress-related issues post-coating.
Innovation Solution
The method involves applying a coating to a bore surface and reshaping it, either by rolling or forming a counter-hardening zone, to compensate for internal tensile stresses before fracture separation, ensuring precise reassembly without additional processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a component is coated with low-melting bearing material, then the bearing surface can withstand high loads, but internal tensile stresses are induced causing distortion and requiring straightening or assembly aids
Solution Approach 1:
The coating is reshaped before fracture separation to pre-compensate for the internal tensile stresses that will cause distortion. By performing the reshaping action in advance, the component halves are prepared to maintain precise fit after separation without requiring subsequent straightening or assembly aids
Solution Approach 2:
The reshaping process applies a counteracting deformation to the coating before fracture, creating preliminary compressive stresses that oppose the subsequent tensile stresses. This preliminary anti-action prevents the harmful distortion effect from occurring during or after fracture separation
2Strength
If a component is coated with high-melting bearing material at high temperature, then the coating achieves good adhesion, but internal stresses are still induced causing spring back or sinking after fracture
Solution Approach 1:
The coating is reshaped before fracture separation to pre-compensate for the internal stresses generated during high-temperature coating processes. This preliminary action ensures that even after the component undergoes fracture separation, the dimensional accuracy is maintained without requiring additional straightening operations
Solution Approach 2:
The reshaping process modifies the physical parameters of the coating (shape, density, stress distribution) to counterbalance the internal stresses. By changing the coating parameters in a controlled manner before fracture, the adverse effects of thermal coating stresses are neutralized
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 ensures that the component halves can be reassembled with a precise fit, avoiding distortion and maintaining functional reliability by counteracting internal stresses through mechanical deformation or pre-formed compressive stresses, thus eliminating the need for straightening or assembly aids.
Implementation Method 1
the coating is mechanically deformed before the component is fractured, in order to compensate for the internal tensile stresses in the coating
Implementation Method 2
The forming preferably includes rolling the coating, in particular deep rolling
Implementation Method 3
A partial heat treatment for the targeted introduction of counterstresses or a reshaping is therefore provided before or after the fracture separation
Implementation Method 4
a counter-hardening zone can also be formed to generate counter-compressive stresses that oppose the inner tensile stresses of the coating
Implementation Method 5
prior to fracture separation of the component
Data Source
Figure 1~2
AI summary
According to a first aspect of the invention, a method for producing a fracture-divided component, in particular a connecting rod, with an at least partially coated bore comprises the following steps: - providing an unfinished component; - applying a coating of a bearing material to a bore surface; and - working the coating, in order to compensate internal tensile stresses in the coating, before fracture division of the component. According to a second aspect of the invention, a method for producing a fracture-divided component, in particular a connecting rod, having an at least partially coated bore comprises the following steps: - providing an unfinished component; - applying a coating of a bearing material to a bore surface before fracture division of the component; and - forming a counter-hardness zone before the application of the coating in order to generate compressive stresses which oppose the internal tensile stresses of the coating.