Cam Follower Roller Surface Roughness and Compression Stress
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Solution Overview
Problem
Existing cam followers experience premature wear of both the cam surface and other contacting components due to uneven surface roughness and hardness differences, leading to peeling and wear issues, particularly when using rollers with coarse outer surfaces and harsh contact conditions.
Innovation Solution
A cam follower design with a roller having a radially outer surface with a material ratio Rmr(C) between 0% and 10%, Kurtosis Rku between 4 and 10, arithmetic mean roughness Ra less than or equal to 0.15, and compression stress between 800 MPa and 1100 MPa, combined with flow-barreling treatment to reduce surface roughness and enhance durability, while maintaining a smoother axial end face with Ra less than or equal to 0.8, preventing excessive wear and ensuring oil film retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the radially outer surface of the roller is made rough by centrifugal barrel treatment, then the roller durability is improved, but the cam surface is worn
Solution Approach 1:
The invention applies different surface qualities to different regions of the roller. The radially outer surface (contacting cam) is given a specific roughness range (Ra 0.03-0.3 μm) to prevent peeling, while the radially inner face (contacting bearing rollers) and axial end faces are kept smooth (Ra ≤ 0.8 μm) to prevent wear of contacting components. This local differentiation resolves the contradiction by optimizing each surface for its specific function.
Solution Approach 2:
The invention changes the surface roughness parameter from the conventional coarse state (Ra > 0.3 μm) to a controlled fine state (Ra 0.03-0.3 μm) through flow-barreling treatment. This parameter change allows the surface to retain enough roughness for oil retention and peeling prevention while being smooth enough to minimize wear on the cam surface.
2Reliability
If the radially outer surface is made drastically hard, then roller peeling is prevented, but cam surface wear increases
Solution Approach 1:
The invention changes the surface hardness parameter from drastically hard to a controlled hardness range (HRC 58-65) through flow-barreling treatment. This moderate hardness level, combined with the controlled roughness (Ra 0.03-0.3 μm), provides sufficient peeling resistance while minimizing wear on the cam surface, resolving the contradiction between roller durability and cam protection.
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 effectively reduces cam surface wear, retains load-bearing portions, enhances fatigue strength, and prevents separation of surface layers, thereby extending the cam follower's lifespan and maintaining the integrity of contacting components.
Implementation Method 1
a surface treatment of the roller is performed by a flow-barreling
Implementation Method 2
a compression stress S of the outer surface is set to 800 MPa≦S≦1,100 MPa
Data Source
AI summary
A cam follower includes a roller on which a cam rolls. A material ratio Rmr (C) (C: a section level %) of an radially outer surface of the roller is set to relations of 0%<Rmr (10%)≦10%, a Kurtosis Rku of a roughness profile of the outer surface is set to 4≦Rku≦10, an arithmetic mean roughness Ra of the outer surface is set to 0<Ra≦0.15, and a compression stress S of the outer surface is set to 800 MPa≦S≦1,100 MPa.