Worm Gear Drive Manufacturing for Industrial Gearboxes

What is a Worm Gear?

A worm gear consists of a worm (a screw-like gear) that meshes with a worm wheel (a spur gear). It’s used for large speed reductions.

What are the key features and advantages of Worm Gears?

They offer very high reduction ratios in a compact space. They also have a unique locking feature: the worm can easily turn the wheel, but the wheel cannot turn the worm.

What are some common uses and applications for Worm Gears?

They are used in conveyor systems, elevators, and steering systems. Their non-reversible feature makes them ideal for lifting or locking mechanisms.

(1) Worm (shaft):

Material selection → blank turning → rough turning → finish turning → milling → heat treatment → grinding → gear grinding → inspection.
The detailed operation breakdown is shown in Table 1.

(2) Worm wheel:

Material selection → blank turning → rough turning → finish turning → milling → hobbing → milling → inspection.
The detailed operation breakdown is shown in Table 2.

(1) Material selection

Worms are generally made of alloy steel (e.g., 16MnCr5, 20CrMnTi, 20Cr, 40Cr, 42CrMo) or carbon steel (e.g., 40Cr). In most cases, the tooth surface is heat-treated (e.g., carburizing and quenching) to obtain higher hardness, followed by grinding. For example, material 40Cr, 16MnCr5, 20CrMnTi, with a tooth-surface hardness of 45–55 HRC after hardening.

(2) Turning the tooth profile

A CNC lathe is used. Standard inserts must be re-ground to form the required tool geometry. Since the tooth groove profile on the normal section is a straight-sided profile, and the tooth thickness at the pitch-circle height equals the tooth-space clearance—both being 0.5Px —the turning tool is dressed to the dimensions. During turning, the tool is aligned with the normal-plane centerline of the tooth groove to generate the profile.

In machining, one helix is produced first. As the dimension approaches the target, a certain allowance is left. The tool is then set on the opposite flank of the same thread to machine the second helix to size.

(3) Grinding

The tooth-profile accuracy of the worm largely depends on the dressing accuracy of the grinding-wheel profile. To obtain an approximately correct wheel profile, a diamond dresser is used to dress the wheel, cutting along the axial direction. During grinding, the workpiece is mounted between centers and aligned. After grinding, inspection can be performed.