With the rapid development of my country's economy, various light and heavy industries have risen and developed rapidly, and the demand for slurry pumps has also increased. How to manufacture and process slurry pumps with excellent performance in all aspects has become the goal of continuous exploration by contemporary academic circles. . This article mainly describes the use and material of the slurry pump, and the tools suitable for processing the parts of the slurry pump.
1. The purpose and material of the slurry pump?
A slurry pump can also be called a centrifugal pump. It is a mechanical device that uses the rotation of the impeller of the centrifugal pump to increase the energy of the solid and liquid mixed medium and convert electrical energy into kinetic energy and potential energy of the medium.
Due to the harsh working environment of the slurry pump, it often works in the environment of strong acid, strong alkali and other corrosive substances, resulting in a short service life. In order to obtain a higher service life of the slurry pump, high strength, high hardness, corrosion resistance High chromium alloy cast iron with strong corrosion resistance and high corrosion resistance is used as the main material of the slurry pump, such as Cr15Mo3, Cr15Mo2Cu, KmTBCr12, Cr20, Cr26, etc.
The hardness of high-chromium alloy cast iron after casting is as high as HRC60. It is one of the best wear-resistant materials at present. It is mainly used in mining, electric power, metallurgy, coal, environmental protection and other industries to transport slurry containing abrasive solid particles. The working environment of the slurry pump is different, and the name is also changed accordingly. For example, in the fields of coal washing industry, seawater sand selection and dredging river, it is also called mud pump and mud pump.
2. The processing technology of slurry pump parts
There are many parts of the slurry pump, the main components are impeller, pump shaft, sheath, front fender, rear fender, pump casing and shaft seal device. The role of the impeller is to directly transfer the mechanical energy of the prime mover to the liquid to increase the static pressure energy and kinetic energy of the liquid (mainly increase the static pressure energy). The function of the shaft seal device is to prevent the liquid in the pump casing from leaking out along the shaft or the outside air from leaking into the pump casing. The following is a brief introduction to the processing technology of the impeller and pump shaft (as shown in the figure below) of the slurry pump parts.
Processing technology of the impeller: Rough car inlet port ring and front plate surface - fine car front port ring and inner hole (to ensure concentricity requirements) - key slot (to ensure key slot symmetry) - drill impeller balance hole (to ensure uniform size distribution) - Inspection (Balance Test)——Inspect storage.
The processing technology of the pump shaft: rough turning - heat treatment (quenching and tempering) - semi-finishing turning - finishing - milling keyway - grinding outer circle - inspection and storage.
Among them, the pump impeller is the only workmanship part in the slurry pump, and Cr26 is often used as the main material. The impeller has 5-12 blades, and it is difficult to process with a lathe for one reason: Cr26 (high chromium cast iron) has high hardness after casting, and large castings often have casting defects, such as white mouth, hard spots, etc. ; Second, the impeller belongs to intermittent cutting, which increases the difficulty of processing.
3. How to choose tools for processing slurry pump parts
At present, there are three kinds of cutting tools on the market that can process slurry pump parts: carbide cutting tools, ceramic cutting tools and CBN cutting tools. I personally think that CBN cutting tools are more suitable for processing slurry pump parts.
Due to the high hardness of the slurry pump parts after casting or heat treatment, it is not easy to process. Machinery manufacturers first used carbide tools to process slurry pump parts. However, due to the insufficient hardness of the cemented carbide tool body, the processing of slurry pump parts, especially large castings, has uneven surfaces and casting defects. As a result, the cemented carbide tool wears quickly, and the tool needs to be changed before the machining of a workpiece is completed, which affects the processing efficiency and the cost of the tool is high.
Afterwards, ceramic cutters are used, and the characteristics of ceramic cutters will not be explained again, so ceramic cutters are not suitable for processing slurry pump parts. If ceramic cutters are selected, must be without considering the overall benefits of the company, small feed rates selected for finishing the processing of slurry pump parts.
Neither of the above two cutting tools can solve the difficult machining problem of the slurry pump. After that, the CBN cutting tool was developed. Although the brittleness of the CBN cutting tool is an indisputable fact, it is still more impact-resistant than ceramic cutting tools. Yes, but at the beginning it is also mainly suitable for finishing processes. Until later, the non-metallic binder cubic boron nitride tool BN-K1 developed by Halnn tools made the rough machining of slurry pump parts a reality. In terms of hardness: Halnn BN-K1=traditional cubic boron nitride tool>ceramic tool>tungsten carbide tool; in terms of toughness: Halnn BN-K1>traditional cubic boron nitride tool>hard Alloy Knives>Ceramic Knives;
Halnn tools, as a pioneer in the localization of superhard tools and a leader in professional hard material processing tools, first proposed the concept of "cubic boron nitride integral polycrystalline inserts" for rough machining in China, and the exclusive non-metallic binder cubic nitride Boron cutting tools are widely used in high-hardness materials, high-hardness workpieces after heat treatment, and parts of other difficult-to-cut materials, and have broken the monopoly of foreign countries in processing high-hardness and difficult-to-machine materials, and enjoy a high reputation in the academic circle of superhard cutting tools .
The advantages of Halnn non-metallic binder cubic boron nitride cutter BN-K1: compared with cemented carbide cutters, it has higher hardness and better wear resistance; compared with ceramic cutters and traditional cubic boron nitride cutters, it has better impact resistance Strong, can be cut intermittently to process the impeller of slurry pump parts.
The following is a brief introduction to the case of Halnn cutting tools processing the impeller of slurry pump parts.
4. The case of processing the impeller of slurry pump parts by Valin superhard non-metallic adhesive CBN tool BN-K1grade
Processing material: high chromium cast iron Cr26;
Processing procedure: turning outer circle, end face;
Tool: BN-K1grade;
Cutting parameters: vc=75m/min, ap=2.5-5mm, f=0.1mm/r;
Processing method: intermittent cutting; dry cutting.
Processing effect: When turning the impeller, since the impeller has 5-12 blades, the tool has to withstand 5-12 impacts per revolution of the impeller. The BN-K1 CBN tool does not break during intermittent cutting, and the cutting speed of the Halnn non-metallic adhesive CBN tool BN-K1 is higher than that of the ceramic tool, and the single-edge life It is 7 times that of ceramic tools, fully demonstrating the impact resistance of non-metallic binder cubic boron nitride tools, which not only reduces the cost of using tools, but also improves turning efficiency.
5. Conclusion
With the continuous development of modern technology, machinery manufacturers are trying to make the workpiece have a better service life, just as the slurry pump industry also uses more wear-resistant and corrosion-resistant high-chromium cast iron as the main material, which is important for the tool industry It is said that it is invisible pressure. In the face of the above situation, the cutting tool industry can only strive to develop high-quality, high-performance and high-efficiency cutting tool materials in order to adapt to the development of the times.