The worm gear provides the conversion of motion on the principle of a second pair or an inclined plane. In this case, the diameters of long and initial cylinders are distinguished. The pole of engagement is the tangency point of the initial cylinders.
The worm gear includes a screw (which is called a worm) and a wheel. The angle of intersection of the shafts of the wheel and screw may be different. However, as a rule, it is equal to ninety degrees. The worm gear has an advantage over the helical gears. It manifests itself in the fact that the initial contact of the links is carried out not at a point, but along a line. The wheel rim, which includes a worm gear, has a concave shape. The screw thread can be left or right, multi-start or single-start.
Worms are distinguished by the shape of the surface where the thread is formed. In accordance with this, there are globoidal and cylindrical. Given the shape of the profile, curvilinear and rectilinear types are distinguished. The most common are cylindrical worms. For parts with a straight profile in the section, the turns are outlined by an Archimedean spiral. Therefore, they are called Archimedean worms. They are similar to trapezoidal threaded spindles. They can be cut on a thread-milling or conventional lathe.
Practice has shown that the worm gear motor is characterized by increased efficiency, provided that the thread hardness is increased. In recent years, highly hard polished parts have become more common. For processing products, special
grinding wheels with a shaped profile are used. However, this complicates the processing and reduces the accuracy in the manufacture. In this regard, the manufacture of Archimedean worms is carried out with unpolished turns. For processed high-hard elements use involute parts having a corresponding profile in the end section. The main advantage of these worms is the ability to grind the coils using the flat side of the wheel. But along with this, special machines are needed.
NMRV worm gear reducer is a special electric motor. The advantages of the part in a compact size, noiselessness and smooth operation. Thanks to the unified mounting dimensions , this gearbox can be used instead of units from other manufacturers. Due to the output shaft deployed at a right angle and the universal case, somewhat modernized, the part can be located in those places where it is impossible to install models with a coaxial shaft arrangement. Thanks to modern injection molding technology, advanced unit models are being produced today.
The worm wheel is cut with appropriate cutters. They are made identical to the screws. However, the cutters have an outer diameter and cutting edges twice the size of the radial clearance. When cutting a workpiece, the wheel and the mill carry out mutual movement according to the same principle as the worm gear.