6-lectures-machine_elements_____video_links

Introduction

Course: Design of Machines and Instruments 2

Institution: VILNIUS TECHFaculty of MechanicsInstructor: Oleksandr KapustynskyiCourse Code: [MEMKB17222]

Machine Elements

Definition: Fundamental components of a machine.

Categories:

  • Structural components: Frame members, bearings, axles, splines, fasteners, seals, lubricants.

  • Mechanisms: Gear trains, belt or chain drives, linkages, cam and follower systems, brakes, clutches.

  • Control components: Buttons, switches, indicators, sensors, actuators, and computer controllers.

Importance of Covers

Covers, while not classified as machine elements, play a crucial role in the improvement and maintenance of machines. Their key contributions include:

  • Styling of Machines: Covers enhance the aesthetic appeal of machines, making them more visually attractive and in line with design standards. This is particularly important in consumer-facing products where design plays a significant role in marketability.

  • Operational Interfaces: They provide operational interfaces that connect mechanical components to users, ensuring safe and efficient interactions. For example, they can house controls like buttons or dials, protecting them from damage while being easily accessible to the operator.

  • Protection: Covers shield internal components from external elements such as dust, moisture, and mechanical damages, which can lead to wear and tear. This protective function is vital for maintaining the longevity and reliability of machines.

  • Thermal Management: By enclosing machine parts, covers help in managing heat dissipation, preventing overheating, and facilitating cooling processes. This can be particularly important in high-performance machines where heat build-up could lead to failure.

  • Safety Features: Covers enhance safety by preventing accidental contact with moving parts or high-temperature surfaces. This is particularly important in industrial applications where operator safety is a priority.

Structural Elements

List of Structural Elements:

  • Beams

  • Struts

  • Bearings

  • Fasteners

  • Keys, splines, cotter pins

  • Seals

  • Machine guarding

Mechanical Elements

List of Mechanical Elements:

  • Engine

  • Electric motor

  • Actuator

  • Shafts

  • Couplings

  • Belt, Chain, Cable drives

  • Gear trains

  • Clutches

  • Brakes

  • Flywheels

  • Cam and follower systems

  • Linkages

Couplings

Definition and Role:

  • Shaft Coupling: Critical component in power transmission systems, connecting shafts to transmit power and movement.

Types of Couplings:

  • Rigid

  • Flexible

  • Sleeve or muff

  • Split muff

  • Flange

  • Gear

  • Universal joint (Hooke’s joint)

  • Oldham

  • Diaphragm

  • Jaw

  • Beam

  • Fluid

Purposes of Couplings

Functions:

  • Power transmission

  • Shock and vibration absorption

  • Accommodation of misalignment

  • Interrupt heat flow

  • Overload protection

Operating Characteristics

Couplings maintain a connection that allows for:

  • Robustness against misalignment.

  • Adaptability for maintenance and service without disassembling connected shafts.

  • Transfer of torque over short distances.

Types of Specific Couplings

Rigid Coupling Characteristics: Allows little to no movement between shafts. Used in precise alignment applications such as vertical pumps and high torque situations.

  • Flexible Coupling Definition: Allows for some movement while isolating vibrations, reducing wear.

  • Beam Coupling Design: High flexibility for parallel, axial, and angular misalignments, ideal for low-power applications.

  • Split Muff Coupling Design: Simplifies assembly without moving shafts. Suitable for medium heavy-duty applications.

  • Flange Coupling Summary: Connects shafts with flanged end connections, ideal for medium to heavy-duty applications and sealed systems.

  • Oldham Coupling: Specializes in lateral shaft misalignment with flanged ends and a center disc.

  • Diaphragm Coupling: Excellent for accommodating multiple alignment types and transmitting high torque at high speeds without lubrication.

  • Jaw Coupling: Used in low power applications, accommodating angular misalignment effectively.

  • Fluid Coupling: Transmits torque using hydraulic fluids, found in automotive and industrial applications.

Gears

Types of Gears Introduced:

  • Spur gear

  • Helical gear

  • Bevel gear

  • Worm gear

  • Gear rack

Specific Gear Types:

  • Spur Gear: Most common, cylindrical with parallel teeth, designed for high accuracy.

  • Bevel Gear: Cone-shaped, ideal for intersecting shafts, available in various types.

  • Helical Gear: Winding teeth pattern, superior performance in speed and load but requires thrust bearings.

  • Gear Rack: Converts rotational motion to linear motion using a flat gear rod.

  • Worm Gear: Non-intersecting, sliding contact gears producing smooth, quiet rotation.

Fasteners

Examples include anchoring bolts, rivets, cotter pins, and screws among others.

Power Screw

Converts rotary motion into linear motion through helical movement.

Gear Train

Structure of gears mounted on a frame to ensure effective rotational transmission.

Flywheel

Stores kinetic energy and aids in maintaining steady rotation during operation.

Conclusion

Encouragement for further study and application in mechanical elements. Best wishes for success in the course.