There are different types of cutters that perform specific functions. What do hob? What types of this instrument are and where they apply? With these questions and to understand.
Types of hobs
Well for starters, definitely worth to define briefly what the hob, and what it represents.
by Itself, hob is a rack and pinion type multiblade tool, which is based on the method of rounding. The task of such mills quickly and accurately touch the surface of the workpiece. Base tool is the standard worm with slotted flutes. And on the gear wheel profile hob has a variety of Evol’vent located on the circumference evenly. the Coils may have a right or left direction. to slice helical gear left, apply left direction of turns, but right turns are designed to cut prevoshodnye spur wheel.
hob the teeth can be polished or sanded surface. Itself the design of the entire or team, respectively. In addition, hob is single-start or multiple-start.
Next, consider a carbide hobbing cutter.
Carbide hob can be involute, kruglovatoe, cycloidal gearing. This tool is made from cast iron, structural steel, hard steel, non-ferrous metals, non-metallic materials.
Module cutter serves as a guide to determine the manufacture of cutters (as mentioned above, the hob can be team or whole). Usually, integral cutters are fully hard alloy, and its modulus of 0.2-1.5 millimeters. To national structural mills, which are cutting elements made of hard alloy, include milling cutters with module 1,5 – 10 mm.
Teams of hob are divided into types:
— Worm milling cutter with carbide relief teeth;
— Worm milling cutter with carbide blade-teeth;
— Sharp hob.
If to consider the shape of the rear surface, hob can be sharp or relief. Hob relief relief of a surface of revolution or a helical surface relief, and the Archimedean spiral, but razor-sharp hob has a rear surface of the teeth of cylindrical or flat. Sharpening razor-sharp cutters – a complicated matter. In order to carry out such a difficult operation – you need a full disassembly of the tool and some special tools grind his teeth.
razor-Sharp hob is only applicable if you want to process gears, bronze, polyamide resin and similar materials. Why such mill is used only for the above functions? The answer is quite simple – it is known that the surfaces of the teeth sharpening is «nostro». To improve the conditions of the side cutting edges have an opportunity to increase the angles of the side cutting edges. This increases the durability of the cutter. But here’s the thing: if you increase the rear corners, the angle of taper is reduced, and therefore, it affects the strength of the cutting edges – it is reduced.
Also, hob is used for cutting helical gears left or prevoshodnyj spur wheel.
of Course, the cutter worm, due to its design features and functional capabilities, is one of the most used tools. I want to note that this mill is very profitable in small scale production.