Tools

Tool History

As early as the 28th to the 20th century in China, brass cones, copper drills, knives, and other brass knives have emerged in China. 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.

The rapid development of cutting tools came in the late 18th century with the development of machines such 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 twist drill was invented in 1822, but it was not produced until 1864 as a commodity.

In 1868, Muchert made a tool alloy steel containing tungsten. In 1898, Taylor of the United States. White invented high speed tool 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. In 1938, Germany's Degussa obtained patents on ceramic tools. 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 1969, the Sandvik Steel Company of Sweden patented a chemical vapor deposition process for the production of titanium carbide coated carbide inserts. 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 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.

Tool classification

The tool can be divided into five categories according to the form of the workpiece machining surface:
Tools for machining a variety of outer surfaces, including turning tools, planers, milling cutters, external broaching tools, and boring tools;
Hole machining tools, including drills, reamers, files, reamers, and broaches on the inside;
Thread cutting 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 circular saw blades, band saws, bow saws, cutting tools and saw blade cutters and so on.

Tool structure elements

Surface to be machined - The surface to be removed on the workpiece.
Machined surface - The surface of the workpiece that has been cut by the tool.
Transition surface (synonym: machining surface) - The part of the surface on the workpiece formed by the cutting edge, which will be cut in the next pass, the next turn of the tool or workpiece, or cut by the next cutting edge.
Front (Synonym: rake face) - The surface on which the chips flow on the tool. It acts directly on the metal layer being cut and controls the blade surface along which the chips are discharged.
Back (Synonym: flank) - The surface opposite to the surface created in the work on the workpiece.
Main back (synonym: main flank) —- The cutter intersects with the front to form the back of the main cutting edge. It faces the transitional surface.
Deputy back (Synonym: Vice flank) —- The tool intersects with the front to form the back of the secondary cutting edge. It faces the processed surface.
The primary cutting edge begins at the point where the primary declination angle is zero on the cutting edge and at least one cutting edge is intended to cut the entire length of the transitional surface on the workpiece.
Secondary cutting edge - The edge of the cutting edge other than the primary cutting edge also starts at the point where the primary declination on the cutting edge is zero, but it extends in a direction away from the primary cutting edge.

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.