Gear Geometry and Applied Theory, Second Edtion
An invaluable reference for designers, theoreticians, students, and manufacturers, this text covers the theory, design, geometry, and manufacture of all types of gears and gear drives.
TABLE OF CONTENTS Gear Geometry and Applied Theory, Second Edtion
Chapter 20: Double-Enveloping Worm-Gear Drives
20.1 INTRODUCTION
The invention of the double-enveloping worm-gear drive is a breathtaking story with two dramatic characters, Friedrich Wilhelm Lorenz and Samuel I. Cone, each acting in distant parts of the world one in Germany and the other in the United States [Litvin, 1998]. The double-enveloping worm-gear drive was invented by both Cone and Lorenz independently, and we have to credit them both for it [Litvin, 1998]. The invention of Samuel I. Cone in the United States has been applied by a company that bears the name of the inventor, known by the name Cone Drive.
The invented gear drive is a significant achievement. The special shape of the worm increases the number of teeth that are simultaneously in mesh and improves the conditions of force transmission. The conditions of lubrication and the efficiency of the invented drive (in comparison with a worm-gear drive with a cylindrical worm) are substantially better due to the special shape of lines of contact between the worm and gear surfaces (see below).
The theory of double-enveloping worm-gear drives has been the subject of intensive research by many scientists. This chapter is based on the work by Litvin [1994]. We consider in this chapter the Cone double-enveloping worm-gear drive.
20.2 GENERATION OF WORM AND WORM-GEAR SURFACES
Worm Generation
The worm surface is generated by a straight-lined blade (Fig. 20.2.1). The blade performs rotational motion about axis O b with the angular velocity ? ( b ) = d ? b /dt,...
Copyright Faydor L. Litvin and Alfonso Fuentes 2004 under license agreement with Books24x7
