Estudio de las curvas epicicloide y evolvente utilizadas en el perfil ...
Estudio de las curvas epicicloide y evolvente utilizadas en el perfil ...
Estudio de las curvas epicicloide y evolvente utilizadas en el perfil ...
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<strong>Estudio</strong> <strong>de</strong> <strong>las</strong> <strong>curvas</strong> epicicloi<strong>de</strong> y <strong>evolv<strong>en</strong>te</strong> <strong>utilizadas</strong><br />
<strong>en</strong> <strong>el</strong> <strong>perfil</strong> <strong>de</strong> trabajo <strong>de</strong> <strong>en</strong>granajes que operan con<br />
distancia <strong>en</strong>tre c<strong>en</strong>tros variable<br />
Study of epicycloid and involute curves used<br />
in gear teeth working profile of variable<br />
c<strong>en</strong>ter distance transmissions<br />
L. I. Negrín*, R. Franco<br />
Departam<strong>en</strong>to <strong>de</strong> Mecánica Aplicada y Dibujo, Facultad <strong>de</strong> Ing. Mecánica<br />
Universidad C<strong>en</strong>tral “Marta Abreu” <strong>de</strong> Las Vil<strong>las</strong>,<br />
Santa Clara, Cuba.<br />
*linegrin@fim.uclv.edu.cu<br />
Resum<strong>en</strong><br />
En este trabajo se realiza un estudio <strong>de</strong> <strong>las</strong> <strong>curvas</strong> epiciloidales y <strong>evolv<strong>en</strong>te</strong>s <strong>de</strong> círculo <strong>en</strong> sus formas g<strong>en</strong>erales, con <strong>el</strong> objetivo<br />
<strong>de</strong> formar <strong>el</strong> <strong>perfil</strong> <strong>de</strong> trabajo <strong>de</strong> los di<strong>en</strong>tes <strong>de</strong> los <strong>en</strong>granajes que operan con distancia <strong>en</strong>tre c<strong>en</strong>tros variable. Primeram<strong>en</strong>te<br />
se parte <strong>de</strong> <strong>las</strong> expresiones g<strong>en</strong>erales <strong>de</strong> estas <strong>curvas</strong> y se <strong>de</strong>sarrollan <strong>las</strong> fórmu<strong>las</strong> para <strong>de</strong>terminar algunas<br />
propieda<strong>de</strong>s <strong>de</strong> <strong>las</strong> mismas, como <strong>el</strong> radio <strong>de</strong> curvatura, la evoluta, etc. Aquí se realiza también la <strong>de</strong>mostración <strong>de</strong> que la<br />
<strong>evolv<strong>en</strong>te</strong> <strong>de</strong> círculo es un caso particular <strong>de</strong> la epicicloi<strong>de</strong>, <strong>de</strong>mostración que no aparece <strong>en</strong> la literatura especializada.<br />
Con posterioridad se hace una comparación t<strong>en</strong>i<strong>en</strong>do <strong>en</strong> cu<strong>en</strong>ta <strong>las</strong> propieda<strong>de</strong>s cinemáticas <strong>de</strong> los <strong>en</strong>granajes formados<br />
por <strong>las</strong> difer<strong>en</strong>tes <strong>curvas</strong>. Como conclusiones <strong>de</strong>l trabajo se plantea que la <strong>evolv<strong>en</strong>te</strong> <strong>de</strong> círculo común ti<strong>en</strong>e <strong>las</strong> mejores<br />
propieda<strong>de</strong>s para <strong>en</strong>granajes que trabajan con una variación <strong>de</strong> la distancia <strong>en</strong>tre c<strong>en</strong>tros m<strong>en</strong>or que <strong>el</strong> 5 %, mi<strong>en</strong>tras que<br />
la epicicloi<strong>de</strong> alargada garantiza un mejor funcionami<strong>en</strong>to para <strong>en</strong>granajes que trabaj<strong>en</strong> con una variación <strong>en</strong>tre <strong>el</strong> 5 y <strong>el</strong><br />
10 %.<br />
Palabras claves: Engranajes, <strong>curvas</strong> planas.<br />
Abstract<br />
In this paper a study of the epicycloids and involute curves in their g<strong>en</strong>eral form is carried out with the purpose of using<br />
them both in the <strong>de</strong>sign of the working profile of the teeth of gears which operate with variation of distance betwe<strong>en</strong> operation<br />
c<strong>en</strong>ters. First from these g<strong>en</strong>eral forms new formu<strong>las</strong> were <strong>de</strong>v<strong>el</strong>oped to find some properties of these curves such as<br />
radius of curvature, etc. Besi<strong>de</strong>s it is <strong>de</strong>monstrated that the involute is a particular case of the epicycloid, <strong>de</strong>monstration<br />
that does not appear in the bibliography available. Finally a comparison is ma<strong>de</strong> taking in to account the kinematics properties<br />
of the gears formed by the differ<strong>en</strong>t curves. As conclusion it is stated that the common involute has the best properties<br />
for gears that operate with a variation of distance betwe<strong>en</strong> c<strong>en</strong>ters lower than 5%, while ext<strong>en</strong><strong>de</strong>d epicycloid provi<strong>de</strong>s a<br />
better performance for gears that operate with a variation of distance betwe<strong>en</strong> c<strong>en</strong>ters that rates from 5% to 10%.<br />
Key words: Gears, plane curves.<br />
1 Introducción<br />
Los di<strong>en</strong>tes <strong>de</strong> <strong>las</strong> transmisiones que trabajan con distancia<br />
<strong>en</strong>tre c<strong>en</strong>tros variable <strong>de</strong>b<strong>en</strong> ser mas largos que los<br />
<strong>de</strong> <strong>las</strong> transmisiones comunes (K<strong>en</strong>t W, 1996). En la biblio-<br />
Revista Ci<strong>en</strong>cia e Ing<strong>en</strong>iería. Vol. 25 No. 2. 2004<br />
grafía especializada consultada solam<strong>en</strong>te se tratan <strong>las</strong> <strong>curvas</strong><br />
epicicloidales y <strong>evolv<strong>en</strong>te</strong>s “comunes”, <strong>en</strong> cuyos casos<br />
<strong>el</strong> aum<strong>en</strong>to <strong>de</strong>l radio exterior está limitado por <strong>el</strong> espesor <strong>de</strong><br />
la punta <strong>de</strong>l di<strong>en</strong>te; y la disminución <strong>de</strong>l radio interior no<br />
repercute <strong>en</strong> la zona <strong>de</strong> trabajo, una vez que su valor es in-