The development of knives occupies an important position in the history of human progress. As early as the 28th century BC to the 20th century BC, copper cones and 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 mastery of carburizing technology. The drills and saws at that time were somewhat similar to modern flat drills and saws.
However, the rapid development of knives was accompanied by the development of steam engines and other machines in the late 18th century. In 1783, Lene of France first produced a milling cutter. In 1792, Mosley in the United Kingdom produced silk cones and teeth. The earliest documented invention of the burdock was in 1822, but it was not until 1864 that it was produced as a commodity.
At that time, the knives were made of overall high-carbon tool steel, and the cutting speed was about 5 meters/minute. In 1868, Mushete of the United Kingdom made tungsten alloy tool steel. In 1898, Taylor and White of the United States invented high-speed steel. In 1923, Shileteer of Germany invented cemented Carbide.
When alloy tool steel is used, the cutting speed of the tool is increased to about 8 m/h, when high-speed steel is used, it is more than twice as high, and when cemented carbide is used, it is more than twice as high as high-speed steel. The surface quality and dimension accuracy of the workpiece produced by cutting are also greatly improved.
Due to the relatively high price of high-speed steel and cemented Carbide, tools have been welded and mechanically clamped. From 1949 to 1950, the United States began to use convertible blades on car knives and soon applied them to milling knives and other knives. In 1938, Deguodegusa obtained a patent for ceramic knives. In 1972, General Electric of the United States produced polycrystalline artificial diamonds and polycrystalline cubic boron nitride blades. These non-metallic tool materials allow the tool to be cut at higher speeds.
In 1969, Shanteweike, Sweden, obtained a patent for the production of titanium carbide coated carbide carbide blades using chemical vapor deposition. In 1972, Bangsha and Lagulan of the United States developed a physical vapor deposition method that coated the surface of cemented carbide or high-speed steel tools with titanium carbide or titanium nitride rigid layers. The surface coating method combines the high strength and toughness of the matrix material with the high hardness and wear resistance of the surface layer, so that the composite has better cutting performance.
Tools can be divided into five categories according to the form of the workpiece surface. Tools for processing various outer surfaces, including tool, planer, milling cutter, outer surface drawing knife and file cutter; Holes processing tools, including drill bit, hole drill, boring tool, reamer and inner surface drawing knife; Thread processing tools, including screw cones, plate teeth, automatic opening and closing thread cutting heads, thread tool and thread milling cutter; Gear machining tools, including hob, cutter, razor, Bevel gear machining tools; Cut cutting tools, including toothed circular saw blades, strip saws, bow saws, cutting knives, saw blades, milling cutters, etc.. In addition, there are combination knives.
According to the cutting movement and the corresponding blade shape, the tool can be divided into three categories. Universal tools, such as tool, planer, milling cutter(excluding forming cutter, shaping cutter and shaping cutter), boring cutter, drill bit, hole drill, reamer and saw; Forming tools, the blades of such tools have the same or close to the same shape as the section of the machined workpiece, such as forming tool, shaping cutter, forming milling cutter, drawing knife, conical reamer and various thread machining tools; The spreading tool is a tooth surface or similar workpiece of a gear that is processed by an expansion method, such as a hob, a cutter, a razor, a Bevel gear planer, and a Bevel gear milling cutter.
The structure of various tools consists of clamping parts and working parts. The clamping part and the working part of the integral structure tool are made on the knife body; The working part of the toothed structure tool(knife tooth or blade) is mounted on the knife body.
The clamping part of the tool has two kinds of holes and handles. Holed tools rely on the inner hole set on the spindle or axis of the machine tool to transmit torsional torque through axial or end surface bonds, such as cylindrical milling cutter, sleeve milling cutter and so on.
Handled knives usually have rectangular handles, cylindrical handles, and conical handles. Car knives, planer knives, etc. are generally rectangular handles; The conical handle bears axial thrust by the taper and transmits torque by means of friction. Cylinder handles are generally suitable for smaller cutting tools such as burdock drills and vertical milling cutters. The torsion torque is transmitted by the friction force generated when clamping. The handles of many handled knives are made of low-alloy steel, while the work part is welded with high-speed steel.
The working part of the tool is the part that produces and processes the chip, including the blade, the structure that breaks or rolls the chip, the space where the chip or chip can be stored, and the channel of the cutting liquid. The working part of some knives is the cutting part, such as the cutter, planer, boring cutter and milling cutter; The working parts of some knives include cutting parts and calibration parts such as drill bits, hole drill, reamer, inner surface drawing knives, and silk cones. The cutting part is used to remove the chip with the blade, and the calibration part is used to repair the cut surface and guide the cutter.
The structure of tool working part includes integral, welding and mechanical clamping. The overall structure is to make a cutting edge on the blade; The welding structure is to braze the blade to the steel blade; There are two kinds of mechanical clamping structures. One is to clamp the blade on the blade body, and the other is to clamp the brazed knife head on the blade body. Carbide tools are generally made of welded structures or mechanical clamping structures; Ceramic tools are mechanical clamping structure.
The geometric parameters of tool cutting have a great influence on cutting efficiency and machining quality. Increasing the front angle can reduce the plastic deformation of the cutting layer when the cutting surface is squeezed, and reduce the friction resistance of the cutting debris flowing through the front, thereby reducing the cutting force and cutting heat. However, increasing the front corner will reduce the strength of the cutting edge and reduce the heat dissipation volume of the knife head.
In selecting the tool's angle, it is necessary to consider the influence of a variety of factors, such as workpiece materials, tool materials, processing properties(rough, refined), etc., and must be reasonably selected according to the specific circumstances. In general, the tool angle refers to the marking angle used for manufacturing and measurement. When the actual work is done, the actual work angle and the angle of marking are different due to the different installation positions of the tool and the change in the direction of cutting movement, but the difference is usually small. small.
Tools must be made of materials of high temperature hardness and wear resistance, necessary bending strength, impact toughness and chemical inertia, good workmanship(cutting, forging, heat treatment, etc.), and not easily deformed.
Usually when the hardness of the material is high, the wear resistance is also high; When the bending strength is high, the impact toughness is also high. However, the higher the hardness of the material, the lower its bending strength and impact toughness. High speed steel has high bending strength and impact toughness, and good processability. Modern is still the most widely used tool material, followed by cemented Carbide.
Polycrystalline cubic boron nitride is suitable for cutting high hardness quenched steel and hard cast iron. Polycrystalline diamonds are suitable for cutting non-ferrous metals, alloys, plastics, and fiberglass. Carbon tool steel and alloy tool steel are now used only as tools such as file, plate teeth and silk cones.
The cemented carbide convertible blades have now been coated with titanium carbide, titanium nitride, alumina hard layer or composite hard layer by chemical vapor deposition. The physical vapor deposition method under development can be used not only for cemented carbide tools, but also for high-speed steel tools such as drill bits, rollers, silk cones and milling cutters. Hard coatings act as barriers to chemical diffusion and heat conduction, slowing the tool's wear speed during cutting, and the life of coated blades is about 1 to 3 times higher than that of uncoated blades.
Due to the high temperature, high pressure, high speed, and parts that work in corrosive fluid media, more and more difficult to process materials are used, and the level of automation and the requirements for machining accuracy are getting higher and higher. In order to adapt to this situation, the development direction of tools will be to develop and apply new tool materials; Further development of the tool's vapor deposition coating technology, the deposit of higher hardness coating on the high toughness and high strength substrate, to better solve the contradiction between hardness and strength of tool materials; Further develop the structure of the transpose tool; Improve the manufacturing precision of the tool, reduce the difference in product quality, and optimize the use of the tool.
Tool material is large