Gear hobbing refers to the process of using a broaching machine to cut the grooves, known as gear teeth, into a component. Machines that cut gear teeth are capable of cutting gears with different numbers and varying sizes of teeth. Gear hobbing is used to make teeth for many different kinds of gears, including spur, crown, helical and worm.
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Advantages of Gear Hobbing
Gear hobbing as a process provides many advantages, including a high productivity rate, economical and efficient operation, accuracy, close tolerances, versatility and smooth finishes.
Application of Gear Hobbing
Gear hobbing machines are used to make components used in various industries, including the aerospace, automotive, construction, hardware and manufacturing sectors. Specific products include the cycloid gears used in clocks and helical gears that are less noisy then most gear systems as well as the most basic gear design, the spur gear and worm gears, which are used in the gearboxes of vehicles and are vital to the engine and transmission productivity.
Design of Gear Hobbing
Like all broaching processes, gear hobbing machines are hydraulic cutting tools used to cut holes in metal, wood and plastic materials. Broaching teeth come in many different sizes and spacing configurations, depending on the part that is being broached. There are two different kinds of broaches: internal broaches, which are used to cut completely through the material, and external broaches, which are commonly called blind broaches and are used to make indentations and shapes on the surface of a material. External or blind broaches are used in the gear hobbing process.
- Gear hobbing machines are fully automated and consist of four major parts: the chuck, which is also known as a clamp and is usually clamping the work-piece horizontally to the vertical hob piece; a tailstock, which supports the sides of the gear being made so that it stays steady while being hobbed; the cylindrical hob, which is what makes the cuts in the gear, has helical cutting teeth itself and is usually mounted on a spindle that is connected to the fourth major part of the hobbing machine, the drive motor.
- The hob can be a single thread, double thread or triple thread, depending on how fast productivity is required. These machines can be large or small, depending on what type of gears they are meant to hob. Small versions can produce gears as small as a fraction of a millimeter or as large as three meters.