Paper tube machine slitting double side blade flat round knife tube trimming skd-11/HSS
Industrial tool material and its selection: tool material mainly refers to the material of the cutting part of the tool. The cutting performance of the tool directly affects the production efficiency, processing quality and production cost. The cutting performance of the tool depends first on the material of the cutting part; secondly, whether the selection and design of the geometry and tool structure are reasonable.
1. Basic requirements for tool materials
In the cutting process, the cutting part of the tool must not only bear a large cutting force, but also withstand the high temperature caused by chip deformation and friction. To maintain the cutting ability of the tool, the tool should have the following cutting performance.
1. High hardness and wear resistance
The hardness of the tool material must be higher than the hardness of the workpiece material. It should be above HRC60 at room temperature. Generally speaking, the higher the hardness of the tool material, the better the wear resistance.
2. Sufficient strength and toughness
The cutting part of the tool must bear a lot of cutting force and impact force. Therefore, the tool material must have sufficient strength and toughness.
3. Good heat resistance and thermal conductivity
The heat resistance of the tool material means that it can still maintain its hardness and strength at high temperatures. The better the heat resistance, the stronger the tool material's ability to resist plastic deformation and wear resistance at high temperatures. The better the thermal conductivity of the tool material, the easier the heat generated during cutting is conducted out, thereby reducing the temperature of the cutting part and reducing tool wear.
4. Good workmanship
In order to facilitate manufacturing, the tool material is required to have good machinability. Including hot workability (thermoplasticity, weldability, hardenability) and mechanical workability.
5. Good economy
2. Common tool materials
There are many types of tool materials. Commonly used tool steels include: carbon tool steel, alloy tool steel and high-speed steel, cemented carbide, ceramics, diamond and cubic boron nitride.
Carbon tool steel and alloy tool steel are only suitable for hand tools because of their poor heat resistance.
Ceramics, diamonds, and cubic boron nitride are only used in a relatively small range due to brittleness, poor manufacturability, and high prices.
The most commonly used tool materials are high-speed steel and cemented carbide.
1. High speed steel
It is a high-alloy tool steel with more alloy elements such as tungsten, molybdenum, chromium, vanadium added to alloy tool steel. It has high strength, toughness and heat resistance, and is currently the most widely used tool material. Because it is easy to get a sharp edge when sharpening, it is also called "Front Steel".
According to different uses, high speed steel can be divided into ordinary high speed steel and high performance high speed steel.
1) Ordinary high-speed steel Ordinary high-speed steel has a certain hardness (62 ~ 67 HRC) and wear resistance, high strength and toughness, the cutting speed when cutting steel is generally not higher than 50 ~ 60m/min, not suitable for high-speed cutting And cutting of hard materials. Common grades are W18Cr4V, W6Mo5Cr4V2.
2) High-performance high-speed steel Increase the content of carbon and vanadium in ordinary high-speed steel or add some other alloy elements to obtain new steel grades with higher heat resistance and wear resistance. But the overall performance of this type of steel is not as good as ordinary high-speed steel. Commonly used grades are 9W18Cr4V, 9W6Mo5Cr4V2, W6Mo5Cr4V3, etc.
2. Cemented carbide
Cemented carbide is a powder metallurgy product sintered by carbides with high hardness and melting point, sintered with Co, Mo, Ni as a binder. Its normal temperature hardness can reach 78～82 HRC, can withstand high temperature of 850～1000℃, cutting speed can be 4～10 times higher than high speed steel. However, its impact toughness and flexural strength are far worse than high-speed steel, so it is rarely made into a monolithic tool. In actual use, the cemented carbide blade is often fixed to the blade body by welding or mechanical clamping.
The cemented carbide currently produced in my country is mainly divided into three categories:
1) Class K (YG)
Namely tungsten cobalt, composed of tungsten carbide and cobalt. This kind of cemented carbide has good toughness, but poor hardness and wear resistance, and is suitable for processing brittle materials such as cast iron and bronze. Commonly used grades are: YG8, YG6, YG3, and the tools they make are suitable for roughing, semi-finishing and finishing. The number indicates the percentage of Co content. YG6 contains 6% Co. The more Co, the better the toughness.
2) Class P (YT)
That is tungsten cobalt titanium, which consists of tungsten carbide, titanium carbide and cobalt. This kind of cemented carbide has good heat resistance and wear resistance, but poor impact resistance and is suitable for processing tough materials such as steel. Commonly used grades are: YT5, YT15, YT30, etc., where the numbers indicate the percentage of titanium carbide content, the higher the content of titanium carbide, the better the wear resistance and the lower the toughness. These three grades of carbide tools are suitable for roughing, semi-finishing and finishing.
3) Type M (YW)
That is tungsten cobalt titanium tantalum niobium. It is composed of a small amount of rare metal carbide (TaC or NbC) added to tungsten cobalt titanium cemented carbide. It has the advantages of the first two types of cemented carbide. The tools made with it can process both brittle materials and tough materials. At the same time, it can also process difficult materials such as high-temperature alloys, heat-resistant alloys and alloy cast iron. Commonly used grades are YW1, YW2.
3. Introduction to other tool materials
1. Coated Carbide
This material is coated on the hard alloy substrate with good toughness and strength or high speed steel substrate by chemical vapor deposition (CVD) method or physical vapor deposition (PVD) method. Tool material obtained from extremely high refractory metal compounds. By this method, the cutter has both the strength and toughness of the matrix material and high wear resistance. Common coating materials are TiC, TiN, Al2O3, etc. TiC has good toughness and wear resistance; TiN has good resistance to oxidation and adhesion; Al2O3 has good heat resistance. The coating material can be selected according to different needs during use.
2. Ceramic
The main component is Al2O3, the blade hardness can reach 78 HRC or more, can withstand high temperatures of 1200 ~ 1450 ℃, so it can withstand higher cutting speeds. But the bending strength is low, the impact toughness is poor, and it is easy to fall. Mainly used for finishing of steel, cast iron, high hardness materials and high precision parts.
3. Diamond
There are two kinds of diamonds, man-made and natural. The materials used for cutting tools are mostly man-made diamonds, whose hardness is extremely high, up to 10,000 HV (cemented carbide is only 1300 ~ 1800 HV). Its wear resistance is 80 to 120 times that of cemented carbide. But the edge is poor, and it has a great affinity for iron family materials. Therefore, it is generally not suitable for processing ferrous metals, mainly used for high-speed finishing of hard alloys, glass fiber plastics, hard rubber, graphite, ceramics, non-ferrous metals and other materials.
4. Boron nitride (CNB)
This is a synthetic super-hard tool material, its hardness can reach 7300 ~ 9000HV, second only to the hardness of diamond. However, it has good thermal stability, can withstand high temperature of 1300~1500℃, and has little affinity with iron group materials. But the strength is low and the weldability is poor. At present, it is mainly used for processing hardened steel, chilled cast iron, high-temperature alloys and some difficult-to-machine materials.
The choice of tool materials should be comprehensively considered in terms of performance, process performance, price and other factors, so as to make reasonable choices. For example, when turning 45 steel and free forging gear blanks, due to the irregular surface of the workpiece and oxide scales, the impact force during cutting is large, and the K type (tungsten cobalt type) with good toughness is better than the P type (tungsten cobalt titanium type) favorable. Another example is the use of YT when turning shorter steel threads. However, because the turning tool is subject to impact at the cutting point of the workpiece, it is easy to jump, so it is generally advantageous to use YG. Although its thermal rigidity is not as good as YT, but the workpiece is short, the heat dissipation is easy, and the thermal rigidity is not the main contradiction.
