- Apr 03, 2018 -
The development of the tool occupies an important position in the history of human progress. In China as early as the 28th to the 20th century BC, brass cones, copper cones, drills, knives, and other copper knives have appeared. In the late Warring States period (3rd century BC), copper knives were made due to the possession of carburizing technology. Bits and saws at the time were similar to modern flat drills and saws.
However, the rapid development of cutting tools came in the late 18th century with the development of such machines as steam engines. In 1783, René of France first produced a milling cutter. In 1792, Modsley of the United Kingdom made taps and dies. The earliest documented invention of the twist drill was in 1822, but it was not produced as a commodity until 1864.
The tool at that time was made of high-carbon tool steel and the allowable cutting speed was about 5 m/min. In 1868, Muchert made a tool alloy steel containing tungsten. In 1898, Taylor and the United States. White invented high speed steel. In 1923 Schreiter of Germany invented cemented carbide.
When alloy tool steels are used, the cutting speed of the tool is increased to about 8 m/min. When high-speed steel is used, it is increased by more than two times. When using carbide, it is more than twice that of high-speed steel. The workpiece surface quality and dimensional accuracy are also greatly improved.
Due to the high price of high-speed steel and hard alloys, the tool has a welded and mechanically clamped structure. From 1949 to 1950, the United States began to use indexable inserts on lathes and soon to be applied to milling cutters and other tools. In 1938, Germany's Degussa obtained patents on ceramic tools. In 1972, General Electric of the United States produced polycrystalline synthetic diamond and polycrystalline cubic boron nitride inserts. These non-metallic tool materials allow the tool to cut at higher speeds.
In 1969, the Sandvik Steel Company of Sweden patented a chemical vapor deposition process for the production of titanium carbide coated carbide inserts. In 1972, Bangsa and Rakoland of the United States developed a physical vapor deposition method to coat carbide or HSS cutters with a hard layer of titanium carbide or titanium nitride. The surface coating method combines the high strength and toughness of the base material with the high hardness and wear resistance of the surface layer, so that the composite material has better cutting performance.
The tool can be divided into five categories according to the form of the workpiece surface. Tool for machining a variety of outer surfaces, including turning tools, planers, milling cutters, broaches, boring tools, etc.; hole-cutting tools, including drills, reamers, boring tools, reamers, and broaches on the inner surface; thread machining Tools, including taps, dies, automatic opening and closing threads, thread turning tools and thread milling cutters; gear cutting tools, including hobs, pinion cutters, shaving cutters, bevel gear cutting tools, etc.; cutting tools, including inserts Circular saw blades, band saws, bow saws, cutting tools, saw cutters, etc. In addition, there are combination cutters.
According to the cutting movement mode and the corresponding blade shape, the tool can be divided into three categories. General-purpose tools, such as turning tools, planers, milling cutters (not including shaped turning tools, shaping planers, and forming cutters), boring tools, drills, reamers, reamers, saws, etc.; forming tools, cutting edges of such tools It has the same or nearly the same shape as the cross-section of the workpiece to be machined, such as forming lathes, forming planers, forming cutters, broaches, conical reamers, and various thread cutting tools, etc.; Teeth or similar workpieces, such as hobs, pinions, shavers, bevel gears, bevel gear cutters, etc.
The structure of various tools consists of the clamping part and the working part. The clamping part and the working part of the monolithic tool are made on the tool body; the working part (blade or blade) of the insert tool is mounted on the tool body.
The clamping part of the tool has holes and handles. The holed cutter relies on the inner hole to be set on the spindle or mandrel of the machine tool, and the torsional moment is transmitted by means of an axial key or an end face key, such as a cylindrical milling cutter, a set face milling cutter and the like.