According to the different types of gears to be processed, gear processing machine tools can be divided into two major categories: cylindrical gear processing machine tools—gear hobbing machines, gear shaping machines, gear turning machines, etc.
Bevel gear processing machine tools - processing straight bevel gears: gear planing machine, gear milling machine, gear pulling machine. Processing of spiral bevel gears: gear milling machine. The shape of the processed tooth line is an extended involute: bevel gear milling machine. Finishing of gear tooth surfaces: gear honing machines, gear shaving machines and gear grinding machines.
1. Gear hobbing machine
Uses a hob to rough and finish machining straight teeth, helical teeth, herringbone gears and worm gears according to the development method. It has a wide processing range and can achieve high precision. Or high productivity; the gear shaping machine uses a gear shaping cutter to process straight teeth, helical gears and other tooth-shaped parts according to the generation method, and is mainly used to process multiple gears and internal gears; the gear milling machine uses a forming milling cutter according to the indexing method. Method machining, mainly used for processing instrument gears with special tooth shapes; gear shaving machine is an efficient machine tool that uses a gear shaving cutter to finish gears; gear grinding machine uses a grinding wheel to finish hardened cylindrical gears or gear cutter teeth The gear honing machine is a machine tool that uses the free meshing between the honing wheel and the processed gear to eliminate hardened gear burrs and other tooth surface defects; the gear extrusion machine uses the high-hardness, cutting-edge-free extrusion wheel and the workpiece. It is a machine tool that engages freely and polishes the tiny unevenness on the tooth surface to improve accuracy and smoothness; the gear chamfering machine is a machine tool that rounds the tooth ends of internal and external meshing sliding gears and is used in the production of gear transmissions and other Indispensable processing equipment for gear shifting mechanisms. Cylindrical gear processing machine tools also include gear hot rolling mills and gear cold rolling mills.
Bevel gear processing machine tools are mainly used to process the teeth of bevel gears such as spur teeth, helical teeth, arc teeth and extended epicycloid teeth.
Spur bevel gear planing machine is a machine tool that uses pairs of planing cutters to rough and finish straight bevel gears according to the generation method. Some machine tools can also plan helical bevel gears. In small and medium-sized enterprises, It is the most widely used in mass production.
2. Double cutterhead straight bevel gear milling machine
Use two milling cutterheads with staggered teeth to mill the left and right teeth in the same tooth slot according to the generation method. Surface, high production efficiency, suitable for batch production. Due to the relative movement between the milling cutter disc and the workpiece in the non-tooth length direction, the bottom of the milled tooth slot is arc-shaped, and the processing module and tooth width are both limited. This kind of machine tool can also be equipped with automatic loading and unloading devices to achieve stand-alone automation.
The spur bevel gear broaching machine is a machine tool that uses the forming method to cut a tooth slot from the solid wheel blank in one revolution of a large-diameter broaching cutter. It is the most productive machine tool among bevel gear cutting machine tools. Because the cutting tools are complex and expensive, and each workpiece requires a special cutterhead, it is only suitable for mass production. Machine tools generally have automatic loading and unloading devices.
The spiral bevel gear milling machine uses a spiral bevel gear milling cutter to rough and finish the spiral bevel gears and hypoid gears according to the generation method. There are precision cutting machines and rough cutting machines. Machines and gear broaching machines and other variations.
The spiral bevel gear grinding machine is a machine tool used to grind hardened spiral bevel gears to improve the accuracy and smoothness. Its structure is similar to the spiral bevel gear milling machine, but with The grinding wheel replaces the milling cutter disc and is equipped with a grinding wheel dresser, which can also grind hypoid gears. 3. Extended epicycloidal bevel gear milling machine
Use the extended epitrochoidal bevel gear milling cutter or the double-cutter body combined end milling cutter to continuously index and cut the teeth according to the generation method. of machine tools. When cutting teeth, the cradle milling cutter and the workpiece make continuous rotational motion, and at the same time the cradle makes a feed motion to process a workpiece. The cradle reciprocates once. The continuous rotation of the milling cutter disc and the workpiece enables the workpiece to obtain continuous indexing with a certain number of teeth and form a tooth length curve. The rotation of the cradle and the additional motion of the workpiece are combined to produce a generating motion, so that the workpiece obtains a toothed curve.
The quasi-involute bevel gear milling machine uses a taper hob and a machine tool that continuously indexes the teeth according to the generation method. When cutting teeth, the tapered hob first cuts with its large end, and then with its smaller diameter end. In order to ensure that the cutting speed is consistent during the entire cutting process, the machine tool relies on a continuously variable transmission device to control the hob speed. When cutting teeth, the rocking table, hob Both the knife and the workpiece perform continuous rotational motion. To process one workpiece, the oscillating table reciprocates once. The rotation of the cradle and the workpiece produces generated motion through the differential mechanism, so that the workpiece obtains a tooth profile curve with equal heights along the tooth length.
The supporting equipment of the bevel gear processing machine tool includes a grinder for grinding the milling cutter disc and the cutting edge of the cutter disc, a gear grinding machine for grinding the paired bevel gears, and a machine for testing the meshing and contact conditions of the paired bevel gears. Bevel gear rolling inspection machine and quenching press to prevent tooth heat treatment deformation, etc.
4. Motion analysis of gear hobbing machine
Most of the most widely used gear processing machine tools are vertical. Processing: Straight and helical external meshing cylindrical gears, worm gear horizontal hobbing machine, used for processing small module gears in the instrument industry and processing shaft gears, splined shafts, etc. in the general machinery manufacturing industry.
5. Gear hobbing principle
Evolved from the meshing transmission principle of a pair of staggered shaft helical gears. The number of teeth of one gear in the pair of meshing transmission pairs is reduced to several or one , the helix angle β increases to a large value (that is, the helix angle ω is very small), and it becomes a worm. The worm is then grooved and backed to become a gear hob.