Envelope worm gear: A highly efficient and precise special transmission device
Classification： Blog
Release time：2025-07-24
An enveloping worm is a device with a special structure in mechanical transmission. Its core feature is that the helical tooth surface of the worm and the tooth surface of the worm wheel can form close conjugate contact. This contact form makes the transmission matching between the two more accurate. Compared with ordinary cylindrical worms, the tooth surface of the enveloping worm is not a simple regular curved surface; its shape is more complex. It is this complex tooth surface structure that gives it unique transmission performance.
Enveloping worms are mainly divided into two major types, each with distinct structural characteristics:
1. Toroidal Worm (Hourglass Worm): From the appearance, this type of worm is toroidal, like an hourglass shape that is concave in the middle and slightly convex at both ends. This special shape design allows the worm wheel and worm to cover a larger area during meshing, so that the pressure on the unit area can be dispersed, thus having a higher load-carrying capacity and stable operation under heavy load conditions.
2. ZI Worm (Cone Worm): Its worm tooth surface is conical. This conical structure makes the relative sliding between the tooth surfaces more reasonable during transmission, resulting in less energy loss and thus higher transmission efficiency. It can reduce unnecessary energy waste during power transmission.
In terms of characteristics and advantages, enveloping worms are outstanding. Due to the large tooth surface contact area, it can withstand large loads and performs stably in heavy-duty transmission scenarios. At the same time, the large contact area also makes the transmission process smoother, reducing the impact and vibration during tooth meshing and thus reducing operating noise. In terms of transmission efficiency, it also performs well, usually reaching 85%-95%, higher than some traditional worm transmissions. Moreover, because the tooth surface wear is more uniform, its service life is also relatively long. However, it also has certain limitations. Due to the complex tooth surface structure and extremely high requirements for contact accuracy, the manufacturing process needs to strictly control various parameters, so the manufacturing precision requirements are high, and the corresponding production cost will also be relatively high.
Based on these characteristics, enveloping worms are widely used in many fields: In heavy machinery, such as metallurgical equipment and mining machinery, it can cope with high-intensity power transmission needs and ensure the stable operation of the equipment; in machine tool indexing mechanisms, its standard transmission performance can ensure the accuracy of indexing and ensure the dimensional accuracy of processed parts; in lifting equipment, it can reliably transmit power, making the lifting and movement of heavy objects smoother; at the same time, in precision transmission systems, such as the drive part of precision instruments, it can also meet the high requirements for transmission accuracy and stability.
In general, enveloping worm transmission is suitable for occasions requiring high load-carrying capacity, high-precision transmission, and long service life. However, due to its complex tooth surface design, the manufacturing process requires specialized processing equipment and exquisite craftsmanship, and the design and manufacturing difficulty is relatively large, which also makes it necessary to comprehensively consider performance requirements and cost factors in its application.
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