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Selection of blade material of cemented carbide shield knife

Selection of blade material of cemented carbide shield knife

(Summary description)The shield cutter is composed of a hob and a scraper. The choice of steel material for the hob ring is very important.

Selection of blade material of cemented carbide shield knife

(Summary description)The shield cutter is composed of a hob and a scraper. The choice of steel material for the hob ring is very important.

Information

The shield cutter is composed of a hob and a scraper. The choice of steel material for the hob ring is very important.

The material of the hob cutter ring, according to the working conditions of the cutter ring, the cutter ring material should meet the following properties:

1, high yield strength, to avoid crushing and deformation of the blade end under high stress;

2, high enough hardness, increase wear resistance, reduce cutter ring wear;

3, good impact toughness, improve the crack propagation power of the material, and prevent the cutter ring from breaking;

4, good anti-tempering performance, improve the thermal stability of the material, and ensure that the cutter ring does not reduce the hardness during the process of hot charging and rolling the rock mass;

5, good thermal and cold processing performance, low material cost.

The cutter ring matrix must not only have good wear resistance, but also ensure high impact toughness. The most important internal influence that affects the wear resistance of shield hobs is the chemical composition of the tool material. The following measures can be taken to improve the performance of the hob:

1, control the carbon content of the tool material;

2. Adding chromium, molybdenum, vanadium, silicon and other secondary phase forming elements to the steel intentionally increases the number of precipitated phases to form fine and dispersed coherent and semi-coherent hard spots, thereby improving the resistance to a certain extent Abrasiveness;

3, by adjusting the content of each element, control the content, shape and distribution of each carbide, thereby effectively improving the wear resistance of metal materials.

The scraper blade is the key part of the scraper to scrape the soil and protect the cutter body from being worn. It is usually made of cemented carbide. The scraper of the shield tool is arranged with cemented carbide of different shapes and properties. Strength and wear resistance are the keys to improving tool life and efficiency.

Choose high-performance WC-Co cemented carbide.

1, using super coarse-grained cemented carbide. The coarser the WC grains and the higher the Co content, the better the toughness and fatigue strength of the tool, and the higher the impact resistance. At present, the grain size of ultra-coarse-grained cemented carbide WC has reached more than 7~8μm.

2, low-pressure sintered cemented carbide is used to improve the uniformity of the WC-Co alloy structure and reduce the porosity in the alloy structure.

3, adding a small amount of TaC to the WC-Co alloy can improve the high temperature strength and high temperature hardness of the alloy, and can improve the impact toughness and oxidation resistance of the alloy.

4, using super-hard composite materials. Develop and prepare special cemented carbide and diamond composite blade materials for shield cutting tools, which are used in some key parts and particularly abrasive working conditions.

Previous: The use of cemented carbide tools
Next: Causes and preventive measures of hard alloy brazing cracks
Previous: The use of cemented carbide tools
Next: Causes and preventive measures of hard alloy brazing cracks
The

The tube is an industrial tooth in tungsten steel industry, which is widely used

1.As a typical representative of super hard metals, hard alloy as an industrial tooth, its wear resistance, corrosion resistance and high hardness, high strength characteristics make it widely used, especially some special work in the extreme environment of the core working parts, such as oil and gas, automobiles, ships, iron and steel mines and other scale industrial production. Good performance and long service life are effective ways to improve the efficiency of industrial production.  Zigong Dingli alloy Material Co., LTD. Self-produced and self-sold carbide pipe and custom production and processing, according to customer's drawing requirements of production and processing. The conventional carbide tube dimensions are as follows:  1. Maximum diameter 74 mm,  2. Minimum diameter 5mm,  3. Maximum diameter 68 mm,  4. Minimum diameter 0.1mm,  5. The maximum length of carbide tube is 360mm 2.For those of you who use cemented carbide tubing, the following are some of the specifications for regular production:  1. Phi phi is 16 * 1.5 * 330  2. Phi phi phi 18 * 2 * 330  3. Phi phi 20 * 2 * 330  2 x330 25 * 4. Phi phi  28 * 3 5. Phi phi 330  6. Phi 32 * 3 * 330
2022-11-01
Milling

Milling cutter material requirements

Basic requirements for folding milling cutters to cut parts of material 1) High hardness and wear resistance: at room temperature, the cutting part of the material must have enough hardness to cut into the workpiece; With high wear resistance, the tool does not wear, prolong the service life. 2) good heat resistance, cutting tool in cutting process will produce a lot of heat, especially at higher cutting speed, the temperature will be very high, therefore, the cutting tool material should possess good heat resistance, both remained high hardness at high temperature, has to continue cutting performance, this is the nature of the high temperature hardness, also known as hot hard or red hardness. 3) high strength and good toughness: in the cutting process, the tool to withstand a lot of impact, so the tool material to have a high strength, otherwise easy to fracture and damage. Because milling cutter will be impacted and vibrated, therefore, milling cutter material should also have good toughness, it is not easy to collapse edge, broken. Folding milling cutter common materials 1) High speed tool steel (referred to as high speed steel, front steel, etc.), divided into general and special purpose high speed steel two kinds. It has the following characteristics: A, high content of alloy elements tungsten, chromium, molybdenum, vanadium, quenching hardness up to HRC62-70. It can still maintain high hardness at 600℃. B, good edge strength and toughness, strong vibration resistance, can be used to manufacture cutting speed of general cutting tools, for poor rigidity of the machine tool, the use of high speed steel milling cutter, can still smooth cutting. C, good process performance, forging, processing and grinding are relatively easy, but also can manufacture more complex shape of the tool. D, compared with cemented carbide materials, it still has the disadvantages of lower hardness, red hardness and poor wear resistance. 2) cemented carbide: metal carbide, tungsten carbide, titanium carbide and cobalt based metal binder by powder metallurgy process. Its main characteristics are as follows: A, can withstand high temperature, around 800-1000℃ can still maintain good cutting performance, cutting can choose 4-8 times higher than high-speed steel cutting speed. B, high hardness at room temperature, good wear resistance. C, low bending strength, poor impact toughness, the blade is not easy to grind very sharp. Commonly used cemented carbide can be divided into three categories: Tungsten cobalt cemented carbides (YG) Commonly used brands YG3, YG6, YG8, in which the number represents the percentage of cobalt content, the more cobalt content, the better toughness, the more impact and vibration resistance, but will reduce the hardness and wear resistance. Therefore, the alloy is suitable for cutting cast iron and non-ferrous metals, and can also be used for cutting heavy impact blank and hardened steel and stainless steel parts. Titanium cobalt cemented carbide (YT) Commonly used grades are YT5, YT15, YT30, the number represents the percentage of titanium carbide. Carbide containing titanium carbide, can improve the bond temperature of steel, reduce friction coefficient, and can make the hardness and wear resistance slightly increased, but reduce the bending strength and toughness, make the quality of brittle, therefore, this kind of alloy is suitable for cutting steel parts. General cemented carbide In the above two kinds of hard alloy to add just the right amount of rare metal carbides, such as tantalum and niobium carbide carbide, make its grain refining, improve its hardness under normal temperature and high temperature hardness, wear resistance, bonding temperature and oxidation resistance, can make the toughness of the alloy increased, therefore, this kind of hard alloy cutter has good cutting performance and generality, Its brands are :YW1, YW2 and YA6, etc., because its price is more expensive, it is mainly used for difficult processing materials, such as high strength steel, heat resistant steel, stainless steel and so on.
2022-05-09
April

April 19, 2022 Cobalt lithium nickel market

April 19, 2022 Cobalt lithium nickel market   The cobalt price is stable and has a slight correction. Recently, the liquidity of the domestic market is relatively slow due to the impact of the epidemic, the supply side is limited by geographical pressure and logistics capacity, and the demand side is generally in a general mood due to the slowdown of consumption in electric vehicles and alloys. Market overall trading sentiment remains cautious, local talks have loosened, wait-and-see macro news shock. Lithium prices remain a stalemate, industry is still positive for the medium and long term power energy storage consumption expectations, but the recent geopolitical conflicts and epidemic repeatedly caused supply chain disruption, resulting in limited production and operation activities of automotive companies, affecting the upstream lithium material consumption reduction, part of the product price from a small adjustment. However, due to the current lithium supply is still in the tight range, the overall bottom of the market is still strong. Nickel prices relatively stable, is mainly due to the conflict between Russia and Ukraine under the background, the international market of nickel raw material supply insufficient still, superposition of the main changes in the economic and trade measures, the futures market is still in the game, there's more uncertainty and risk, firms trading cautious, wait-and-see stainless steel and the electric car market demand.
2022-04-20
Application

Application of cemented carbide: domestic shield machine exported to Portugal for the first time

On April 6th, a "cloud acceptance" across thousands of miles was held in Tianjin Dongjiang as promised. The earth pressure balance shield machine manufactured by China Railway Equipment, a state-owned enterprise, successfully passed the acceptance of overseas customers. This is the first time that China's shield machine is exported to Portugal. Shield tunneling machine is a kind of tunneling machine using shield tunneling method. It is closely related to cemented carbide, which is known as "industrial tooth", that is, cemented carbide is the preferred material for cutting tools of high-performance shield tunneling machine.   Cemented carbide is a hard compound by refractory metal such as tungsten carbide, niobium carbide and binder composed of elements such as metals, such as cobalt, nickel alloy material, high hardness, high wear resistance, high strength, strong shock resistance, good toughness and heat resistance and corrosion resistance, so better than other materials such as steel manufacture tool is more suitable for application in the shield construction machine.   The basic working principle of the shield machine is that a steel component of a cylinder pushes forward along the axis of the tunnel while excavating the soil. It is mainly used for subway, railway, highway, municipal, hydropower and other tunnel projects. Due to the harsh working environment of the shield machine, that is, the external water pressure and formation pressure is large, it is easy to cause the wear and scrap of the shield cutter head. This also requires the shield cutter head to have high enough hardness, strength and toughness.   It is understood that the performance of hard alloy shield cutter is closely related to the ratio of raw materials, the morphology and particle size of raw materials. Under normal circumstances, the higher the content of tungsten carbide, the higher the hardness of cemented carbide tool, the worse the toughness; The more complete the crystal shape of tungsten carbide particles and the larger the grain size, the better the toughness of alloy tools. At present, China's tungsten carbide grain size has been able to achieve 9 microns, which makes China's production of hard alloy toughness and wear resistance to reach the international advanced level.   It is reported that the Portuguese import of China's shield machine is the main reason for the country to build a drainage tunnel project. The drainage tunnel project is a single-track tunnel, divided into two sections, with a total length of 5.5 km and a maximum rock strength of 135 mpa. According to the characteristics of the project, China Railway Equipment not only optimized the cutter head of shield machine, but also equipped with advanced control system, so that the whole machine can meet the requirements of soft soil layer and rock tunneling. The equipment is expected to be disassembled and shipped in May.
2022-04-15

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