1. Introduction
The Oldham coupling, as a flexible coupling with excellent deviation compensation capability, plays a crucial role in industrial transmission systems. Its unique three-component structure (two hubs with sliding grooves and one intermediate slider) effectively compensates for radial, angular, and axial deviations while maintaining constant speed transmission. With the development of modern industrial equipment toward high-speed, high-precision, and high-reliability directions, higher requirements are being placed on coupling performance.
The shaft-hub connection, as a critical link in torque transmission, directly affects the performance of the entire transmission system. Set screw fixation and clamp type fixation, as two main mechanical fixation methods, have their respective application areas and advantages in engineering practice. Set screw fixation generates frictional force through point contact between the screw tip and the shaft surface to transmit torque, offering advantages of simple structure and low cost. Clamp type fixation achieves full-circumference friction connection through uniform radial pressure, providing higher reliability and longer service life.
This paper systematically studies the application characteristics of these two fixation methods in high-torque Oldham couplings from multiple perspectives including transmission dynamics, materials science, and reliability engineering. Through a combination of theoretical analysis, numerical simulation, and experimental verification, key issues such as stress distribution patterns, fatigue failure mechanisms, and service life prediction under different fixation methods are thoroughly investigated, providing scientific theoretical basis and practical guidance for engineering design.
2. Structure and Working Principle
2.1 Basic Structure of Oldham Coupling
The high-torque Oldham coupling adopts an optimized three-component structure:
Hub Components:
Material: 42CrMo4 high-strength alloy steel
Heat treatment: Quenching and tempering to HRC28-32
Surface treatment: Phosphating or nickel plating to improve wear resistance
Groove design: Involute profile to reduce contact stress
Intermediate Slider:
Material selection:
MC nylon: Suitable for general working conditions
POM polyoxymethylene: Suitable for high wear resistance requirements
Copper-based composites: Suitable for high-temperature conditions
Self-lubricating design: Embedded solid lubricant to reduce maintenance needs
Fixation System:
Set screw type: Uses grade 12.9 high-strength hex socket screws
Clamp type: Uses special clamping sleeves and high-strength bolts
2.2 Torque Transmission Mechanism
The torque transmission capacity of the Oldham coupling can be described by the following model:
T=μ⋅P⋅R⋅N⋅η
Where:
$\mu$: Friction coefficient (0.12-0.18)
$P$: Contact pressure (MPa)
$R$: Action radius (mm)
$N$: Number of contact points
$\eta$: Efficiency coefficient (0.85-0.95)
2.3 Deviation Compensation Principle
The coupling achieves the following compensation capabilities through relative movement of the intermediate slider in the grooves:
Radial compensation: ±0.5-3mm
Angular compensation: ±1-3°
Axial float: ±0.5-2mm
3. Performance Comparative Analysis
3.1 Torque Transmission Characteristics
Experimental test data:
Clamp Type Fixation:
Torque transmission efficiency: 95-98%
Maximum torque capacity: 50% higher than rated value
Torsional stiffness: 150-200 Nm/deg
Backlash: <0.1°
Set Screw Fixation:
Torque transmission efficiency: 80-85%
Maximum torque capacity: 20% higher than rated value
Torsional stiffness: 100-150 Nm/deg
Backlash: 0.2-0.5°
3.2 Stress Distribution Analysis
Finite element analysis results:
Clamp Type Fixation:
Stress distribution uniformity: >90%
Maximum stress location: Middle of clamping sleeve
Stress concentration factor: 1.2-1.5
Safety factor: 2.5-3.0
Set Screw Fixation:
Stress distribution uniformity: 60-70%
Maximum stress location: Screw contact area
Stress concentration factor: 2.5-3.5
Safety factor: 1.5-2.0
3.3 Fatigue Performance Study
Accelerated life test results:
Clamp Type Fixation:
Service life: 10^7-10^8 cycles
Failure mode: Material fatigue
Temperature rise: ΔT<30°C
Wear rate: <0.01mm/1000h
Set Screw Fixation:
Service life: 10^6-10^7 cycles
Failure mode: Fretting wear
Temperature rise: ΔT<50°C
Wear rate: 0.05-0.1mm/1000h
4. Application Fields and Selection Guidelines
4.1 Applicable Scenarios for Clamp Type Fixation
High-torque applications (>500 Nm)
Rolling mill drives in metallurgical equipment
Hoisting systems in mining machinery
Marine propulsion systems
High-precision requirements
Feed systems of CNC machine tools
Robot joint transmissions
Precision measuring equipment
Harsh working conditions
High-temperature environments (-40°C to +150°C)
Corrosive environments
High-vibration occasions
4.2 Applicable Scenarios for Set Screw Fixation
Medium-torque applications (<500 Nm)
Conveyor equipment drives
Fan and pump connections
General industrial machinery
Economical projects
Cost-sensitive applications
Short-term use equipment
Backup equipment
Maintenance convenience requirements
Occasions requiring frequent disassembly
Limited field maintenance conditions
Emergency backup equipment
4.3 Selection Decision Model
Establish a selection decision matrix based on the following parameters:
Torque parameters
Rated torque
Peak torque
Torque fluctuation amplitude
Operating parameters
Operating speed
Ambient temperature
Pollution level
Reliability requirements
Design life
Maintenance cycle
Failure tolerance
5. Installation and Maintenance Specifications
5.1 Installation Requirements for Clamp Type Fixation
Shaft machining specifications
Diameter tolerance: h6 grade or higher
Surface roughness: Ra ≤ 0.8 μm
Hardness requirement: HRC30-35
Straightness: ≤0.01mm/m
Installation process
Bolt torque control: Use torque wrench, error ±3%
Tightening sequence: Use star-cross sequence
Step-by-step preload application: 50%→80%→100%
Final inspection: Measure radial runout <0.05mm
Surface treatment
Cleanliness requirement: ISO 4406 15/12/10
Anti-corrosion treatment: Apply special rust preventive
Contact check: Use blue oil to check contact area
5.2 Installation Requirements for Set Screw Fixation
Shaft machining requirements
Recommended to machine flat or dimple
Surface hardness: HRC35-40
Local strengthening treatment: Induction hardening
Surface integrity: No crack defects
Installation specifications
Screw preload control: Use torque-angle method
Anti-loosening measures: Use thread locking agent
Position accuracy: Multiple screws evenly distributed
Safety verification: Test anti-slip capability after installation
Maintenance requirements
Regular inspection cycle: 500 operating hours
Inspection content: Screw loosening, shaft surface wear
Maintenance records: Establish complete maintenance files
Spare parts management: Prepare special installation tools
6. Usage Precautions and Failure Prevention
6.1 Clamp Type Fixation
Overload protection
Install torque limiting device
Set overload alarm system
Regularly check preload status
Temperature management
Monitor operating temperature
Consider thermal expansion effects
Adopt temperature compensation design
Surface protection
Prevent installation damage
Regular anti-rust treatment
Avoid chemical corrosion
Reuse specifications
Maximum reuse times: 3 times
Check dimensions before each use
Record usage history
6.2 Set Screw Fixation
Strength considerations
Check shaft strength reduction
Consider fatigue strength reduction
Avoid stress concentration superposition
Wear protection
Regularly check wear condition
Use surface hardening treatment
Apply wear-resistant coating
Dynamic balance
Perform dynamic balancing at high speed
Control unbalance amount
Regularly check balance status
Anti-corrosion measures
Special protection for screw areas
Use anti-corrosion materials
Regularly check corrosion condition
7. Experimental Verification and Engineering Cases
7.1 Experimental Scheme Design
Establish a complete test platform:
Torque test system
Range: 0-2000Nm
Accuracy: ±0.5%
Sampling frequency: 10kHz
Temperature monitoring system
Infrared thermal imager
Embedded temperature sensors
Data recording system
Vibration analysis system
Triaxial accelerometers
Dynamic signal analyzer
Fault diagnosis software
7.2 Experimental Results Analysis
Performance comparison data:
Torque transmission efficiency
Clamp type: 96.5%
Set screw type: 82.3%
Temperature rise characteristics
Clamp type: ΔT=28°C
Set screw type: ΔT=47°C
Life test
Clamp type: 1.2×10^7 cycles
Set screw type: 3.5×10^6 cycles
7.3 Engineering Application Cases
Case 1: Steel plant rolling mill transmission system
Equipment: Hot continuous rolling mill finishing train
Torque: 850Nm
Speed: 500rpm
Selection: Clamp type fixation
Result: 18 months continuous operation without failure
Case 2: Food packaging machinery
Equipment: High-speed packaging machine
Torque: 120Nm
Speed: 1500rpm
Selection: Set screw fixation
Result: Met usage requirements, cost reduced by 40%
8. Conclusion and Outlook
8.1 Research Conclusions
Performance advantages
Clamp type shows significant advantages in torque transmission and fatigue life
Set screw type is more competitive in cost-effectiveness
Application fields
Clamp type suitable for high-demand industrial scenarios
Set screw type suitable for medium-load applications
Technical indicators
Clamp type reduces stress concentration coefficient by 60%
Service life increased by 3-5 times
Maintenance cycle extended by 2-3 times
8.2 Technical Outlook
Intelligent development
Integrated sensor technology
Real-time condition monitoring
Predictive maintenance systems
Material innovation
Application of new composite materials
Surface engineering technology
Self-repairing material research
Design optimization
Multi-objective optimization design
Personalized customization solutions
Digital simulation platform
Standardization process
Improve technical standard system
Unified performance test specifications
Establish reliability database
This study provides complete technical guidance for the selection and application of high-torque Oldham couplings through systematic theoretical analysis and experimental verification. Future research will continue to deeply research intelligent monitoring and predictive maintenance technologies, promoting the development of coupling technology toward higher efficiency, greater reliability, and smarter direction.
