Diaphragm coupling is a type of flexible coupling that utilizes one or more thin, flexible metal diaphragms to transmit torque while accommodating misalignment between connected shafts. This coupling design has gained widespread acceptance across various industrial applications due to its unique combination of high torque capacity, zero-backlash operation, and excellent misalignment accommodation capabilities.
Working Principle
The fundamental principle of diaphragm coupling operation involves the elastic deformation of thin metal diaphragms under torsional, angular, and parallel misalignment conditions. When torque is applied, the diaphragms flex in a controlled manner, allowing for angular misalignment up to 1.5 degrees and parallel misalignment up to 0.5 mm per diaphragm set. The coupling transmits torque through the diaphragms' ability to withstand shear stresses while maintaining flexibility in other directions.
Key Components
A typical diaphragm coupling consists of three main components:
Hub Flanges: These are the connection points to the driving and driven shafts, typically made from high-strength steel or aluminum alloys.
Diaphragm Packs: Single or multiple thin metal diaphragms (usually stainless steel) that provide the flexibility and torque transmission capabilities.
Center Member: In some designs, a spacer or center member connects the diaphragm packs, allowing for easier installation and maintenance.
Types of Diaphragm Couplings
Single Diaphragm Couplings
Utilize a single diaphragm pack
Suitable for moderate torque applications
Compact design with lower moment of inertia
Double Diaphragm Couplings
Feature two diaphragm packs separated by a spacer
Higher torque capacity and better misalignment accommodation
Reduced reaction forces on connected equipment
Continuous Diaphragm Couplings
Single-piece diaphragm design
Excellent balance and high-speed capability
Minimal maintenance requirements
Advantages
High Torque Capacity: Diaphragm couplings can transmit high torque values relative to their size and weight, making them suitable for demanding applications.
Zero Backlash: The solid metal construction ensures no backlash, which is critical for precision positioning systems and servo applications.
Maintenance-Free Operation: Unlike gear or grid couplings, diaphragm couplings require no lubrication and have no wearing parts, reducing maintenance costs.
High-Speed Capability: Excellent balance characteristics allow operation at speeds up to 60,000 RPM or higher, depending on the design.
Electrical Isolation: The non-conductive nature of the coupling (when using non-metallic components) provides electrical isolation between connected shafts.
Torsional Stiffness: High torsional stiffness ensures accurate torque transmission with minimal wind-up, making them ideal for servo applications.
