Popular science knowledge of gear processing machine tools
Gear processing machine tool popular science knowledge Gear processing machine tool is a machine tool for processing the teeth of various cylindrical gears, bevel gears and other toothed parts. Gear processing machine tools have a wide variety of specifications, including small machine tools for processing gears with diameters of several millimeters, large machine tools for processing gears with diameters of more than ten meters, and high-efficiency machine tools for mass production and high-precision machine tools for processing precision gears.
Gear processing machine tools are widely used in various machinery manufacturing industries such as automobiles, tractors, machine tools, construction machinery, mining machinery, metallurgical machinery, petroleum, instrumentation, aircraft and spacecraft.
The ancient gears were shaped by hand-repairing files. In 1540, Toriano of Italy made a gear cutting device using a rotary file when making clocks; in 1783, René of France made a gear processing machine using milling cutters, with cutting racks and inner gears. Gear accessories; around 1820, White in England produced the first machine tool capable of processing cylindrical gears and bevel gears. Machine tools with this performance were developed in the second half of the 19th century.
In 1835, Whitworth of the United Kingdom obtained a patent for a worm gear hobbing machine; in 1858, Schiller obtained a patent for a cylindrical gear hobbing machine; after many improvements, it was not until 1897 that Proford of Germany made a hobbing machine with a differential mechanism. The problem of processing helical gears has been satisfactorily solved. After the gear shaper cutter was made, Fellows of the United States made a gear shaper in 1897.
In the early twentieth century, due to the needs of the automobile industry, various gear grinding machines came out one after another. The gear shaving machine was made in the United States around 1930; the gear honing machine was made in 1956. After the 1960s, modern technology has been applied to some advanced cylindrical gear processing machine tools, such as the use of digital displays on large-scale machine tools to indicate the amount of movement and gear cutting depth; the use of electronic servo systems and numerical control systems on gear hobbing machines, gear shapers and gear grinding machines Replace the mechanical transmission chain and exchange gears; use the programmable controller with fault diagnosis function to control the working cycle and change the cutting parameters; develop the digital control non-circular gear shaper and adaptive control hobbing machine; use electronic sensors on the hobbing machine Detect the movement error of the transmission chain, and automatically feedback and compensate the error.
In 1884, Bill Gram of the United States invented a spur bevel gear planer using a single planer to process the spur bevel gear; in 1900, Bill of the United States designed a machine tool for milling spur bevel gears with a double cutter.
Due to the needs of the automobile industry, a straight bevel gear planer with two planers was manufactured in the United States in 1905, and a spiral bevel gear milling machine was made in 1913; in 1923, a quasi-involute gear appeared Bevel gear milling machine; developed into a gear broaching machine capable of broaching straight bevel gears at one time in the 1930s, mainly used in the manufacture of automobile differential gears.
In the 1940s, in order to meet the needs of the aviation industry, spiral bevel gear grinding machines were developed. In 1944, Swiss Oerlikon Company produced the extended trochoidal bevel gear milling machine; from the 1950s, it has developed a dual-blade combined face milling cutter to process the milling teeth of the extended trochoidal bevel gear. machine.
Gear processing machine tools are mainly divided into two categories: cylindrical gear processing machine tools and bevel gear processing machine tools. Cylindrical gear processing machine tools are mainly used for processing various cylindrical gears, racks, and worm gears. Commonly used gear hobbing machines, gear shaping machines, gear milling machines, gear shaving machines, etc.
The gear hobbing machine uses a hob to rough and finish straight teeth, helical gears, herringbone gears and worm gears according to the generative method. The processing range is wide and can reach high precision or high productivity. The gear shaper uses the generative method with a gear shaper. Processing spur gears, helical gears and other tooth-shaped parts, mainly used for processing multi-connected gears and internal gears; gear milling machine is processed by the indexing method with a forming milling cutter, mainly used for processing instrument gears with special tooth profiles; gear shaving The machine is a high-efficiency machine tool that uses gear shaving cutters to finish gears; gear grinding machines are high-precision machine tools that use grinding wheels to finish hardened cylindrical gears or gear cutter tooth surfaces; honing machines use honing wheels and processed The free meshing of gears is a machine tool that eliminates hardened gear burrs and other tooth surface defects; the extruder uses a high-hardness extruder without cutting edge to mesh freely with the workpiece to grind out the small unevenness on the tooth surface to improve accuracy The machine tool with a high degree of cleanliness; the gear chamfering machine is a machine tool that rounds the tooth ends of the sliding gears meshing inside and outside, and is an indispensable processing equipment for the production of gearboxes and other 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 straight teeth, helical teeth, spiral teeth and extended outer cycloid teeth.
Straight bevel gear planer is a machine tool that rough and finish straight bevel gears with a pair of gear planers according to the generative method. Some machine tools can also plan helical bevel gears, which are the most widely used in small and medium batch production.
The double-cutter spur bevel gear milling machine uses two milling cutters with staggered teeth to mill the left and right tooth surfaces in the same tooth groove according to the generative method. The production efficiency is high and it is suitable for mass production. Due to the relative movement of the milling cutter head and the workpiece in the tooth-free direction, the bottom of the milled tooth groove is arc-shaped, and the processing modulus and tooth width are restricted. This machine tool can also be equipped with an automatic loading and unloading device to realize single machine automation.
The straight-tooth bevel gear broaching machine is a machine tool that cuts a tooth groove from a solid wheel blank by a forming method during one revolution of a large-diameter broaching cutter. It is the most productive machine tool among the bevel gear cutting machine tools. Due to the complexity of the cutting tools, the price is expensive, and each kind of workpiece requires a special cutter head, which is only suitable for mass production. Machine tools are generally equipped with automatic loading and unloading devices.
Spiral bevel gear milling machine uses spiral bevel gear milling cutters to rough and finish spiral bevel gears and hypoid gears according to the generative method. There are variants such as fine cutting machines, rough cutting machines and gear broaching machines. .
Spiral bevel gear grinding machine is a machine tool used to grind hardened spiral bevel gears to improve accuracy and smoothness. Its structure is similar to that of spiral bevel gear milling machines, but it replaces the milling cutter with a grinding wheel. Equipped with a grinding wheel dresser, it can also grind hypoid gears.
The extended outer cycloid bevel gear milling machine is a machine tool that uses the extended outer cycloid bevel gear milling cutter, or the double-cutter body combined end milling cutter, to continuously index and cut gears according to the generative method. During gear cutting, both the cradle milling cutter head and the workpiece make continuous rotation, while the cradle makes feed motion to process a workpiece and the cradle reciprocates once. The continuous rotation of the milling cutter head and the workpiece enables the workpiece to obtain a continuous index of a certain number of teeth and form a tooth length curve. The rotation of the cradle is combined with the additional movement of the workpiece to produce a generative movement, so that the workpiece obtains a tooth profile curve.
A machine tool that uses taper hobs for quasi-involute bevel gear milling machines to continuously index and cut gears according to the generative method. When cutting gears, the taper hob first cuts with the big end, and then cuts with its smaller diameter end. In order to ensure the same cutting speed throughout the cutting process, the machine tool relies on a stepless speed changer to control the speed of the hob. Both the knife and the workpiece make continuous rotary motion, processing a workpiece, and the cradle reciprocates once. The rotation of the cradle and the workpiece generates a generative motion through the differential mechanism, so that the workpiece obtains a tooth profile curve with the same height along the tooth length.
The supporting equipment of the bevel gear processing machine tool includes a sharpener for grinding the cutting edge of the milling cutter and broach, a gear machine for grinding the pair of bevel gears, a bevel gear rolling inspection machine for inspecting the meshing contact of the pair of bevel gears, and tooth prevention Partial heat treatment deformation of the quenching press, etc.