Chain Joint Press-Fit Chamfer for Higher Fatigue Strength
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Solution Overview
Problem
Existing chain designs in mechanical engineering suffer from insufficient fatigue strength due to high interference fits between pins and openings in outer plates, leading to plastic deformation and uneven contact pressure, which compromises the chain's durability under dynamic loads.
Innovation Solution
Incorporating a chamfer with an angle of 0.3° to 2°, preferably 0.5° to 1°, in the press fit area between the bolts and openings of the outer plates to facilitate centering and reduce plastic deformation, ensuring a uniform and higher pressure for improved fatigue strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high interference fit is used between pins and openings in outer plates, then the connection strength is improved, but plastic deformation occurs and contact pressure becomes uneven, reducing fatigue strength
Solution Approach 1:
The patent applies different geometric characteristics to different regions of the pin. The joining chamfer (first region) provides a tapered transition zone for gradual load distribution, while the cylindrical central region (second region) maintains the tight interference fit for strong connection. This local differentiation allows the pin to simultaneously achieve both strong connection and uniform contact pressure distribution.
Solution Approach 2:
The joining chamfer is pre-formed on the pin before assembly. This preliminary geometric preparation ensures that during the press-fit assembly process, the load is gradually distributed from the chamfered entrance region into the cylindrical connection region, preventing sudden stress concentration and plastic deformation in the opening area of the outer plate.
2Strength
If high interference fit is used between pins and openings in outer plates, then the connection strength is improved, but plastic deformation occurs leading to non-uniform contact pressure
Solution Approach 1:
The pin is designed with two distinct geometric regions: a joining chamfer region for gradual load introduction and a cylindrical central region for the actual interference fit connection. This local quality differentiation ensures that the high contact pressure is concentrated in the cylindrical region while the chamfered region provides a stress-distributing transition zone, preventing plastic deformation and ensuring uniform contact pressure.
3Ease of manufacture
If conventional pin design without chamfer is used, then manufacturing is simpler, but fatigue strength is insufficient under dynamic loads
Solution Approach 1:
The patent modifies the geometric parameters of the pin by introducing a joining chamfer with specific angle and length dimensions. This parameter change creates a gradual transition zone that distributes stresses more evenly during assembly and operation, significantly improving fatigue strength while maintaining compatibility with conventional manufacturing processes for creating the chamfered geometry.
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
The chamfered design enhances the fatigue strength of the chain by providing a more uniform press fit, reducing plastic deformation and improving the chain's durability under alternating stress conditions.
Implementation Method 1
leading to plastic deformation and uneven contact pressure
Implementation Method 2
high interference fits between pins and openings in outer plates
Data Source
Figure 1~2
Figure 3~4
AI summary
The present invention relates to a chain for a chain drive with alternating inner and outer chain links, each articulated to one another by means of a chain joint, wherein each outer chain link comprises two outer plates, each with two openings and two pins, and the pins and the openings are each connected to one another by means of a press fit, such that the pins hold the outer plates spaced apart from one another. It is the object of the present invention to provide a chain for a chain drive that avoids the disadvantages known from the prior art and, in particular, leads to higher fatigue strength. This object is achieved according to the invention by forming a chamfer in the area of the press fit between the pins and the openings in the outer plates.