Classification by Overall Structural Shape
This is the most fundamental classification method for worms, covering mainstream application scenarios:
- Cylindrical Worm: Features a cylindrical pitch surface; simple to manufacture and the most widely used type in industry, suitable for standard, low-to-medium power transmission applications.
- Toroidal (Globoidal) Worm: The tooth surface envelops the worm gear, providing 40% more contact area than cylindrical worms and superior load-bearing capacity; commonly used in heavy-duty machinery gearboxes.
- Conical Worm: Geometrically shaped as a truncated cone; specifically used in niche applications involving special crossed-axis transmissions.
Sub-classification of Standard Cylindrical Worms by Tooth Profile Curve
This represents the core sub-classification of cylindrical worms and the most common standard used in engineering:
- Archimedean Worm (ZA Type): Features a straight-line axial tooth profile; easy to manufacture and low-cost, making it suitable for low-speed, light-load applications.
- Involute Worm (ZI Type): Features an involute transverse tooth profile; offers transmission efficiency of 85%–90%, suitable for medium-load speed reducers and elevator drives.
- Normal Straight-Profile Worm (ZN Type): Features a straight-line tooth profile in the normal plane; offers transmission efficiency of 90%–95%, commonly used in heavy-load, high-precision applications.
- Conical-Envelope Cylindrical Worm (ZK Type): The tooth surface is generated by a conical envelope; facilitates grinding, offers high precision, and is seeing increasingly widespread application.
- Circular-Arc Cylindrical Worm (ZC Type): Features a circular-arc tooth profile; offers high load-bearing capacity, excellent lubrication conditions, and low contact stress.
