Rolling Mill Roll with Curved Keyway for Stress Distribution
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Solution Overview
Problem
Conventional rolls experience high tensile stresses around the keyway, leading to wear, fatigue, and failure, especially when using carbide or ceramic rolls, which limits their ability to transmit high rotational torque and results in uneven stress distribution.
Innovation Solution
A roll with a concave curved keyway on its side faces and a key with lower hardness than the keyway surface, allowing for uniform stress distribution and increased contact area, reducing the risk of stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a carbide roll with a key way structure is used, then wear resistance and high temperature mechanical properties are improved, but the roll is easily broken down by high tensile stresses around the key way
Solution Approach 1:
The key way is designed with a concave curved surface instead of a straight or flat configuration. This curvature allows the key to contact the key way at multiple points along its length, distributing the tensile stress more evenly and preventing stress concentration at specific locations that would lead to roll breakdown.
2Reliability
If a carbide roll without key way is used, then tensile stress resistance is improved, but driving force transmission fails when high driving force is applied due to slip between roll and driving axle
Solution Approach 1:
The concave curved key way provides multiple contact points for the key, increasing the effective contact area and friction between the key and key way surfaces. This enhanced contact allows the key structure to transmit high driving forces effectively without causing slip, while the curved geometry continues to distribute tensile stresses uniformly.
Solution Approach 2:
The key is designed with varying cross-sectional area along its length, with the largest area at the center and smaller areas at the ends. This local variation in geometry optimizes the stress distribution and contact characteristics at different locations, allowing the key to effectively transmit driving force while resisting tensile stresses.
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 solution significantly reduces tensile stress, increases the lifespan and driving torque of tungsten carbide or ceramic rolls, and improves the surface quality of rolled products by ensuring uniform stress distribution across multiple keyways.
Implementation Method 1
the driving force of the driving axle to the roll 1 through the frictional force between the roll 1 and the driving axle
Implementation Method 2
a frictional force between the roll 1 and the work piece 7 acts in a direction of obstructing the movement of the key 5
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention relates to a rolling mill and a roll thereof, and more particularly to a roll coupled to a separately manufactured axle and rotating together with the axle in order to perform a rolling process. The roll according to the present invention comprises an inner cylindrical surface, an outer cylindrical surface and both side faces, and at least one key way provided on at least one of the side faces is arranged adjacent to the inner cylindrical surface rather than said outer cylindrical surface, wherein said key way is in a concave curved shape and is a portion of a spherical surface or of an ellipsoidal surface.