What Is Gear-Cutting Machinery?
Gear-cutting machinery refers to machine tools that create grooves in gears through cutting processes. These machines are essential in the manufacture of both rolled and cast gears, offering precise machining for a wide range of gear types.
The types of gear-cutting machinery include hobbing machines, which process external gears using hob cutters; shaping machines, capable of processing both external and internal gears with pinion cutters; and broaching machines, used for manufacturing with broach cutters. Additionally, there are specialized machines for rack gears, worm wheel hobbing, straight bevel gears, and spiral bevel gear cutting.
Applications of Gear-Cutting Machinery
Gear-cutting machinery is utilized in the production of spur gears, helical gears, internal gears, and racks, which are critical for transmitting power between parallel shafts. These machines also facilitate the creation of straight bevel gears, spiral bevel gears, and face gears for cross-shaft applications, where power transmission shafts intersect. Moreover, they are employed in making worm gears, hypoid gears, screw gears (known as staggered shafts), and specialized gears like noncircular gears, conical gears, and intermittent gears.
Features of Gear-Cutting Machinery
Gear-cutting machinery employs various methods such as the creation method, forming method, and gear skiving, tailored to the specific gear being manufactured. For instance, spur gears are typically processed using the generating method, while special gears may require a combination of generating and forming methods. Primarily used for cylindrical gears, these machines include hobbing machines for hobbing, grinding machines for precision shaping, and gear shapers for special gears, combining creation and forming methods as needed.
Aside from spur gears, hobbing machines also machine helical and worm gears. The generating method is noted for its accuracy over the forming method, which processes grooves individually but at a higher cost, especially when using NC (Numerical Control) machine tools.
Types of Gear-Cutting Machinery
Different gear-cutting machinery types are distinguished by their processing methods:
1. Hobbing Machine
This machine performs gear cutting by rotating a hob cutter in contact with the gear blank, featuring cutting edges and grooves to form the gear.
2. Gear Shaper
Using a pinion cutter or rack-type cutter, a gear shaper executes shaping through vertical blade movement. It’s adept at handling special gear shapes, albeit with lower work efficiency.
3. Gear Grinding Machine
High-speed rotation of the grindstone shapes the gears, allowing for high-precision machining of hardened materials.
4. Gear Shaving Machine
Used in the final stages of gear production, this machine smooths the gear surface and corrects alignment through rotating gear-like tools.
5. Bevel Gear-Cutting Machinery
Specializing in bevel gears, this machinery employs a disc-shaped cutting tool for precision cutting.
Structure of Gear-Cutting Machinery
Gear-cutting machinery is capable of producing gears in various shapes:
1. Spur Gear
The most common gear type, featuring teeth parallel to the gear axis for power transmission between parallel gears.
2. Helical Gear
With diagonal tooth traces, helical gears offer easier meshing, quieter operation, and greater strength than spur gears.
3. Internal Gear
Characterized by teeth that face inward, these gears rotate a smaller gear within a cylindrical space.
4. Bevel Gear
Conical in shape, bevel gears transmit power between intersecting shafts. They are classified into straight (with teeth like those of spur gears) and helical bevel gears (with diagonal teeth).
5. Worm Gear
Consisting of a screw-like worm and a matching worm wheel, worm gears change shaft direction and offer compact, quiet operation compared to bevel gears.
6. Rack and Pinion
A rack pinion system converts rotational motion into linear motion, using a straight rod (rack) with teeth and a gear (pinion), commonly seen in camera tripod height adjustments.