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

Gleitlager werden verwendet, um rotierenden Wellen und Achsen Querstabilität zu verleihen.
Betrachten Sie eine Seilwinde mit trockenen oder teilgeschmierten Gleitlagern.
Durch die Drehung der Spule im Uhrzeigersinn rollt sich die Welle an der Innenfläche des Lagers auf, bis sie gleitet und sich stabil dreht.
Es wird ein Freikörperdiagramm der Welle gezeichnet. Zu den Kräften, die auf das System wirken, gehören das Gewicht der Welle, die Rechtskupplung und die Reaktionskraft des Lagers.
Die nicht-kollineare Reaktionskraft ist gleich und entgegengesetzt zum Gewicht und wirkt in einem Winkel relativ zur Oberflächennormalen. Dieser Winkel wird als Winkel der kinetischen Reibung bezeichnet.
Die Wirkungslinie der Reaktionskraft verläuft immer tangential zum Reibungskreis.
Die Momentengleichgewichtsbedingung um den Punkt O ergibt das Wellenmoment.
Für einen kleinen kinetischen Reibungswinkel kann der Sinusterm an die Tangente des kinetischen Reibungswinkels angenähert werden.
Da die Tangente des kinetischen Reibungswinkels gleich dem kinetischen Reibungskoeffizienten ist, wird das Moment erhalten, das erforderlich ist, um den Reibungswiderstand des Lagers zu überwinden.

<ol>
	<li>Hibbeler, R.C. (2016). Technische Mechanik \u2012 Statik und Dynamik. Hoboken, New Jersey: Pearson Prentice Hall. Seite 450.</li>
	<li>Meriam, J.L.; Kraige, L.G. und Bolton, J.N. (2020). Technische Mechanik \u2012 Statik. Hoboken, New Jersey: John Wiley. Seite 364.</li>
	<li>Bier, F.P.; Johnston, E.R.; Mazurek, D.F.; Cromwell, P.J. und Self, B.P. (2019). Vektormechanik für Ingenieure \u2012 Statik und Dynamik. New York: McGraw-Hill. Seiten 459-460.</li>
</ol>

gleitlager

Journal Bearings

Gleitlager sind mechanische Bauteile, die rotierende Wellen und Achsen unterstützen und seitliche Stabilität bieten. Sie sind entscheidend, um Reibung, Verschleiß und Vibration in Maschinen wie Motoren, Turbinen und Pumpen zu reduzieren. Das Prinzip hinter Gleitlagern besteht darin, einen dünnen Schmierfilm zwischen der Lagerfläche und der rotierenden Welle zu erzeugen, der den direkten Kontakt minimiert und die Reibungskräfte verringert. Um das Konzept der Gleitlager besser zu verstehen, betrachten wir eine Seilwinde mit trockenen oder teilweise geschmierten Gleitlagern, die die rotierende Welle unterstützen. Wenn die Rolle im Uhrzeigersinn rotiert, rollt die Welle über die innere Oberfläche des Lagers, bis sie abrutscht und eine stabile Rotation durchführt. <img alt="Figure 1" src="/files/ftp_upload/14326/14326_Figure_1v2.svg" style="text-align: center; height: 300px;"> Eine Freikörperdarstellung der Welle kann gezeichnet werden, um die auf das System wirkenden Kräfte zu analysieren. Diese Kräfte umfassen das Gewicht der Welle, das vertikal nach unten wirkt, das die angewendete Drehmoment darstellende Uhrzeigersinn-Drehmoment und die Reaktionskraft, die das Lager auf die Welle ausübt. Die nicht-kollineare Reaktionskraft ist gleich und entgegengesetzt dem Gewicht der Welle und wirkt unter einem Winkel relativ zur Oberflächennormalen. Dieser Winkel wird als Winkel des Gleitreibung bezeichnet. Die Wirkungslinie der Reaktionskraft ist immer tangential zum Reibungskreis, der den Ort aller möglichen Kontaktpunkte zwischen der Welle und dem Lager darstellt. Durch Anwendung der Momentengleichgewichtsbedingung am Punkt O (dem Mittelpunkt der Welle) können wir das benötigte Wellenmoment zur Aufrechterhaltung einer stabilen Rotation bestimmen. <img alt="Equation 1" src="/files/ftp_upload/14326/14326_Equation_1v2.svg" style="text-align: center; height: 13px;"> Der Sinus-Term in der Gleichung kann für einen geringen Winkel des Gleitreibungswinkels zu dem Tangens des Gleitreibungswinkels approximiert werden. <img alt="Equation 2" src="/files/ftp_upload/14326/14326_Equation_2v2.svg" style="text-align: center; height: 13px;"> Da der Tangens des Gleitreibungswinkels dem Koeffizienten der Gleitreibung entspricht, können wir das Moment berechnen, das erforderlich ist, um den Reibungswiderstand des Lagers zu überwinden. Dieses Moment ist ein wesentlicher Faktor zur Bestimmung der Effizienz und Leistung des Systems. <img alt="Equation 3" src="/files/ftp_upload/14326/14326_Equation_3v2.svg" style="text-align: center; height: 13px;">

Gleitlager

Gleitlager sind mechanische Bauteile, die rotierende Wellen und Achsen stützen und für Seitenstabilität sorgen. Sie sind entscheidend für die Reduzierung von Reibung, ...

Education

Lehre

JoVE Core

Mechanical Engineering

Maschinenbau

Unit 1

Einheit 1

Friction

Reibung

KEY TERMS AND CONCEPTS

KERNBEGRIFFE UND KONZEPTE

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 clockwise, the shaft first rolls up the inner surface of the bearing. It then slips and settles into stable rotation. A free-body diagram of the shaft helps show the forces in the system.

The diagram includes the weight of the shaft, a clockwise couple that represents the applied torque, and the reaction force from the bearing. The reaction force is not collinear with the weight of the shaft. It acts at an angle to the surface normal, and that angle is called the angle of kinetic friction.

The line of action of the reaction force is tangent to the circle of friction. The circle of friction is the set of possible contact points between the shaft and the bearing. By using moment equilibrium about point O, the center of the shaft, the needed shaft moment can be found.

For a small kinetic friction angle, the sine term in the equation can be approximated by the tangent of that angle. Since the tangent of the kinetic friction angle equals the coefficient of kinetic friction, the required moment can be calculated from it. This moment helps describe the bearing’s frictional resistance and its effect on efficiency and performance.

Friction Moment in Journal Bearings

dry friction

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kinetic friction

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characteristics of dry friction

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friction: problem solving

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frictional forces on screws

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upward impending motion

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screw: problem solving

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frictional forces on flat belts

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pivot bearings

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collar bearings

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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...

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key terms and concepts

Learn how journal bearings support rotating shafts, reduce friction, and create the reaction force and moment used to analyze stable rotation.

Friction Moment in Journal Bearings | JoVE K12

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mechanical engineering

Friction Moment in Journal Bearings

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