Name: friction torque in collar bearings
Uploaded: 2023-09-22T11:49:30.000Z
Duration: 1 min 23 s
Channel: JoVE

Подшипники с кольцом — это тип подшипника, используемый в машинах для поддержки осевых нагрузок на вращающиеся валы, он может иметь одно или несколько хомутов.
Рассмотрим подшипник с одним кольцом, на который действует осевая нагрузка. Площадь между внешним и внутренним радиусами кольца является общей площадью контакта подшипника.
При условии равномерной опоры подшипника равномерное нормальное давление может быть выражено как отношение силы к площади подшипника.
Рассмотрим элемент бесконечно малой площади на подшипнике. Сила, действующая на площадь дифференциала, может быть выражена как произведение коэффициента трения, давления и площади дифференциала.
Момент, необходимый для возникновения надвигающегося вращения вала, определяется из уравнения равновесия момента вокруг оси вращения.
Затем интегрирование используется для определения приложенного момента, необходимого для преодоления всех сил трения.
Наконец, подставляя значения дифференциальной силы и площади дифференциала и интегрируя уравнение по общей площади подшипника, можно оценить момент вала.

<ol>
	<li>Хиббелер, Р.К. (2016). Инженерная механика \u2012 Статика и динамика. Хобокен, Нью-Джерси: Пирсон Прентис Холл. С. 447-448.</li>
</ol>

Воротниковые подшипники

Воротниковые подшипники необходимы в различных машинах, предназначенных для поддержки осевых нагрузок на вращающихся валах. В зависимости от конкретного применения и требований, их можно найти с одним или несколькими воротниками.

<img alt="Figure 1" src="/files/ftp_upload/14325/14325_Figure_1v3.svg" style="text-align: center; height: 300px;" />

Рассмотрим однорожковый подшипник, на который действует осевая нагрузка. Общая площадь контакта подшипника представляет собой область между внешним радиусом и внутренним радиусом воротника. Когда предполагается, что подшипник обеспечивает равномерную поддержку, равномерное нормальное давление может быть рассчитано путем деления силы, приложенной к воротнику, на общую площадь контакта подшипника. Это значение представляет среднее распределение давления по поверхности подшипника.

Для дальнейшего анализа сил, действующих на воротниковый подшипник, рассмотрим малый бесконечно малый элемент площади на поверхности подшипника. Сила, действующая на этот элемент площади, является произведением коэффициента трения, давления и дифференциальной площади. Понимание взаимосвязи между этими переменными критично для расчета момента, необходимого для вращения вала.

Предстоящий поворот вала определяется путем анализа уравнения равновесия моментов относительно оси вращения. Это уравнение учитывает все силы и моменты, действующие на вал, включая трения, генерируемые воротниковым подшипником.

<img alt="Equation 1" src="/files/ftp_upload/14325/14325_Equation_1v2.svg" style="text-align: center; height: 39px;" />

Интегрируя уравнение, можно определить приложенный момент, необходимый для преодоления всех этих трений, что инициирует вращение вала. Наконец, для оценки момента вала заменяют дифференциальные значения силы и площади в интегрированное уравнение.

<img alt="Equation 2" src="/files/ftp_upload/14325/14325_Equation_2v2.svg" style="text-align: center; height: 55px;" />

Интегрирование этого уравнения по общей площади подшипника обеспечивает всестороннее понимание сил и моментов, действующих на воротниковый подшипник и необходимого момента для вращения вала.

<img alt="Equation 3" src="/files/ftp_upload/14325/14325_Equation_3v2.svg" style="text-align: center; height: 39px;" />

Подшипники с кольцами имеют важное значение в различных машинах, предназначенных для восприятия осевых нагрузок на вращающиеся валы. В зависимости от конкретного применения и ...

Education

JoVE Core

Mechanical Engineering

Машиностроение

Unit 1

Раздел 1

Friction

Трение

KEY TERMS AND CONCEPTS

ОСНОВНЫЕ ТЕРМИНЫ И ПОНЯТИЯ

Collar Bearings

friction torque in collar bearings

Collar bearings support axial loads on rotating shafts, and their friction helps determine the torque needed to start motion. They are used in many machines and may have a single collar or multiple collars, depending on the application and load needs.

For a single collar bearing under an axial load, the contact area is the ring-shaped region between the external radius and the internal radius of the collar. If the bearing is assumed to support the load evenly, the uniform normal pressure is found by dividing the applied force by this total bearing contact area. This gives the average pressure across the bearing surface.

To study the forces more closely, a small infinitesimal area element is considered on the collar surface. The force on that tiny area equals the friction coefficient times the pressure times the differential area. Using this relationship is important for finding the moment required to rotate the shaft.

The impending rotation of the shaft is found by writing the moment equilibrium equation about the rotational axis. This equation includes the forces and moments on the shaft, along with the frictional forces from the collar bearing. When the equation is integrated over the full bearing area, the applied moment needed to overcome friction and begin rotation can be determined.

Friction Torque in Collar Bearings

dry friction

Dry Friction in Crates and Everyday Motion

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static friction

Static Friction at the Point of Slip

Static friction is the force that keeps two surfaces from starting to slide past each other. It acts when there is a tendency for motion, but not yet actual slipping. This force helps explain everyday actions like walking on the ground and driving a car. A towing example shows how static friction changes as force is applied. A truck pulls a car with a rope, and the car stays still at first. The car is in static equilibrium, which means the forces on it are balanced. Gravity and the normal...

kinetic friction

Sliding Friction Between Moving Surfaces

Kinetic friction is the sliding friction that acts when two surfaces move against each other. It opposes relative motion and acts parallel to the contact surface, in the opposite direction of travel. In the truck and car example, the car first stays still because static friction holds it in place. When the truck’s force becomes greater than the limiting static frictional force, the friction at the contact surface drops to a lower value. The car then begins to slide, and its speed increases. At...

characteristics of dry friction

Static and Kinetic Dry Friction

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types of friction problems

Dry Friction in Crate, Ladder, and Frame Problems

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friction: problem solving

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wedges

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frictional forces on screws

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upward impending motion

Screw Jack Force and Friction Analysis

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self-locking screw

Screw Jack Self-Locking Behavior

A square-threaded screw jack can hold a heavy load because of its self-locking behavior. This feature makes the device more reliable when it is used to lift large weights or apply a strong force. If the screw keeps its position after the turning moment is removed, the jack is self-locking. Self-locking happens because friction changes the way the forces act on the thread. The friction force reverses direction, and the reaction force moves to the other side of the thread’s normal. In this case,...

screw: problem solving

Screw Torque and Self-Locking

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frictional forces on flat belts

Flat Belt Tension and Friction

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flat belts: problem solving

Flat Belt Forces and Pulley Moment

Flat belts transmit power from one pulley to another, and the forces on the belt help determine the moment on a pulley. In this example, a belt wraps around pulleys A and B, with radii of 30 cm and 10 cm. The belt meets the pulleys at a 20 degree angle from the horizontal, which sets up the force balance in the system. As pulley B rotates clockwise, it drives pulley A. That motion creates tension T2 on one side of the belt and tension T1 on the other side. The belt-to-surface contact angle, β,...

pivot bearings

Axial Load Support in Pivot Bearings

Pivot bearings support axial loads on a rotating shaft. A bearing helps two parts move relative to each other while reducing friction and wear. In this design, the pivot is placed at the end of the shaft to carry the axial thrust. The pivot surface can be flat, conical, or truncated, depending on the application. In a flat pivot bearing, the axial load is spread over the bearing area. The pressure is uniform and can be found by dividing the load by the area. To study the forces more closely,...

collar bearings

Collar bearings support axial loads on rotating shafts, and their friction helps determine the torque needed to start motion. They are used in many machines and may have a single collar or multiple collars, depending on the application and load needs. For a single collar bearing under an axial load, the contact area is the ring-shaped region between the external radius and the internal radius of the collar. If the bearing is assumed to support the load evenly, the uniform normal pressure is...

journal bearings

Friction Moment in Journal Bearings

Journal bearings support rotating shafts and axles while helping keep them stable. They are used in machines such as engines, turbines, and pumps. Their job is to reduce friction, wear, and vibration. A journal bearing works by keeping a thin film of lubricant between the bearing surface and the rotating shaft. This film limits direct contact and lowers frictional force. The video uses a rope winch with dry or only partly lubricated journal bearings to show the idea. As the spool turns...

bearings: problem solving

Double-Collar Bearing Torque Calculations

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rolling resistance

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rolling resistance: problem solving

Lawn Roller Force Calculation

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key terms and concepts

Learn how collar bearing contact area, pressure, and friction work together to set the torque needed to start shaft rotation in mechanical systems.

Friction Torque in Collar Bearings | JoVE K12

JoVE Core Mechanical Engineering offers concise, easy-to-understand animated videos covering key topics such as equilibrium, forces, truss analysis, and structural mechanics. Explore their real-world applications, and witness these concepts in action through scientist-led experiments.

mechanical engineering

Friction Torque in Collar Bearings

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