Name: screw torque and self-locking
Uploaded: 2023-09-22T11:49:29.000Z
Duration: 1 min 21 s
Channel: JoVE

Considere un eje de tornillo de rosca cuadrada con un radio medio de 20 milímetros y un paso de 10 milímetros en contacto con un engranaje de placa de radio medio de 35 milímetros. El coeficiente de fricción estática entre el tornillo y el engranaje es de 0,3.
Evalúe el par de resistencia en el engranaje de la placa que puede ser dominado cuando se aplica un momento de torsión de ocho newton-metro al eje.
Inicialmente, calcule el ángulo de fricción estática utilizando el coeficiente de fricción estática y determine el ángulo de avance sustituyendo los valores de avance y radio medio.
Para un movimiento inminente hacia arriba, la fuerza axial desarrollada en el eje se puede determinar sustituyendo los valores correspondientes.
El par de resistencia en el engranaje de la placa es igual al producto de la fuerza axial del eje y el radio medio del engranaje.
Al sustituir los valores, se puede determinar el par de resistencia que puede dominar el momento de torsión aplicado.
Aquí, el ángulo de fricción estática es mayor que el ángulo de avance. Por lo tanto, el eje es autoblocante incluso si se elimina el momento.

<ol>
	<li>Hibbeler, R.C. (2016). Ingeniería Mecánica: Estática. Decimocuarta edición, Nueva Jersey: Pearson. págs. 434-437.</li>
</ol>

tornillo: resolución de problemas

En ingeniería mecánica, la interacción entre un eje de tornillo roscado y una corona de placa implica analizar el par de resistencia en la corona de placa que puede ser vencido cuando se aplica un momento de torsión específico al eje. Para comprender mejor este concepto, considere una situación genérica con un eje de tornillo roscado con un radio medio y una longitud especificados, y una corona de placa con un radio medio especificado. También se proporciona el coeficiente de fricción estática entre el tornillo y la corona. Para evaluar el par de resistencia en la corona de placa que puede ser vencido cuando se aplica un cierto momento de torsión al eje, el primer paso es calcular el ángulo de fricción estática utilizando el coeficiente de fricción estática. El ángulo de fricción estática, denotado como φ, es el ángulo cuya tangente es igual al coeficiente de fricción estática. A continuación, se determina el ángulo de avance sustituyendo los valores del avance y del radio medio. Es igual a la relación entre el avance y la circunferencia del eje. La fuerza axial, denotada como F, es la fuerza que actúa a lo largo del eje del tornillo y que hace que la corona de placa gire. Para un movimiento inminente en una dirección específica, la fuerza axial desarrollada en el eje se puede determinar utilizando una fórmula que involucra el momento de torsión, el ángulo de fricción estática, el ángulo de avance y el radio medio. <img alt="Equation 1" src="/files/ftp_upload/14321/14321_PT_Equation_1v2.svg" style="text-align: center; height: 30px;"> El par de resistencia en la corona de placa es igual al producto de la fuerza axial del eje y el radio medio de la corona. Al sustituir los valores, se puede determinar el par de resistencia que puede vencer al momento de torsión aplicado. Además, si el ángulo de fricción estática es mayor que el ángulo de avance, el eje se bloqueará automáticamente incluso si se quita el momento. Finalmente, se puede determinar si el eje se bloquea automáticamente mediante una serie de cálculos que involucran el ángulo de fricción estática, el ángulo de avance, la fuerza axial y el par de resistencia. Este análisis es crucial para comprender el comportamiento mecánico de los ejes y las coronas de diferentes aplicaciones de ingeniería.

Tornillo: Resolución de problemas

En ingeniería mecánica, la interacción entre un eje de tornillo roscado y un engranaje de placa implica analizar el par de resistencia en el engranaje de placa que ...

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Screw: Problem Solving

screw torque and self-locking

Screw torque and self-locking are analyzed by looking at a threaded screw shaft and a plate gear. The shaft has a mean radius and a lead. The plate gear also has a mean radius. The coefficient of static friction between the screw and the gear is part of the setup.

The first step is to find the static friction angle, φ. This angle is defined by the coefficient of static friction. Next, the lead angle is calculated from the lead and the mean radius of the shaft. It gives the screw geometry needed for the torque analysis.

The axial force, F, acts along the axis of the shaft and drives the plate gear to rotate. For impending motion in a chosen direction, this force is found from a formula that uses the torsional moment, static friction angle, lead angle, and mean radius. The resisting torque on the plate gear is then the axial force multiplied by the gear’s mean radius.

By substituting the given values, the resisting torque can be determined and compared with the applied torsional moment. The same calculations also show whether the shaft is self-locking. If the static friction angle is greater than the lead angle, the shaft stays locked even after the moment is removed.

Screw Torque and Self-Locking

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key terms and concepts

Learn how to calculate axial force, resisting torque, and self-locking for a threaded screw shaft and plate gear using friction and lead angle.

Screw Torque and Self-Locking | JoVE K12

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Screw Torque and Self-Locking

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