Superhard material tools for machining (4)

1.5 Application in reaming

PCBN electroplated reamer has been used in the reaming of hardened steel or hard casting holes. This type of reamer is made of 45 steel or 9CrSi steel with a hardness of 42 HRc, with front and rear guiding and cutting portions. The manufacturing precision of the substrate is high, the design should be reasonable, the diameter of the front guiding part is smaller than the diameter of the cutting edge part by 0.04mm, the length of the cutting area is larger than the depth of the workpiece; the length of the rear guiding is larger than the length of the cutting area, and the diameter should be larger than the diameter of the cutting edge. Small 0.02mm. In order to rinse the chips with the cutting fluid in the reaming and to cool the lubricated surface, the base has two deep spiral grooves.

For example, a factory processing hardened steel workpiece hole φ12.06±0.05mm, hardness 45HRc, bottom hole size φ12±0.01mm, required hole cylindricity 0.005mm, surface roughness Ra0.2μm. A set of five electroplated CBN reamers are used to achieve better economic results.

Some engine manufacturers use PCD or PCBN electroplating reamer to knead the main bearing hole of the cylinder block instead of honing, the processing efficiency is improved several times, and the quality is stable.
Due to the weight reduction and multi-functional requirements, modern automotive gearboxes are increasingly manufactured using die-cast aluminum alloys with a number of stepped shaped holes for surface roughness, roundness, cylindricity, Concentricity, no burr and other quality requirements are very strict. In order to meet the need for efficient and high-precision machining of formed holes, the Japanese company has developed a PCD forming step reamer. High-quality PCD insert materials are used, and high-precision forming grinding technology is used to ensure the shape of the cutting edge, and excellent dimensional accuracy and surface roughness are obtained, so that all cutting edges have excellent cutting performance under different processing loads. The tool achieves satisfactory processing quality, eliminates the disadvantages of sticking knives, extends tool life and reduces machining costs by half.

1.6 Application in drilling processing

It is not uncommon to use PCD drill bits to process glass, engineering ceramics and stone. Many glass deep-processing companies and glass shops mostly use PCD drill bits to drill holes in glass and mirrors. Diamond drill bits on the market range in diameter from 3 to 130 mm. Glass drill bits are inlaid with diamond and resin diamond. Using PCD drill bit to process engineering ceramics and stone, the efficiency is high and the processing quality is good.

Diamond electrolytic drilling can be used to form cylindrical holes (through holes and blind holes), tapered holes and special holes on various difficult-to-machine conductive materials (mostly sintered cemented carbide). It can be machined on the same tool on a single machine without the need to re-adjust tools and blanks.

The most noteworthy is the use of brazed diamond casing drills to drill the "Kevlar composite-special ceramic-aluminum alloy" composite laminate through-holes on the Z5125 vertical drill press. This material is a new type of lightweight composite material which has appeared in recent years. It has the high strength, high fracture toughness, high energy absorption buffer protection ability of Kevlar composite material, and high hardness, high modulus and high ceramic. It has excellent properties such as pressure resistance, wear resistance, corrosion resistance and high temperature resistance. It also has the advantages of anti-rust, anti-penetration and high toughness of aluminum plates. Using a brazed diamond nesting drill, 10 holes were drilled continuously, and there was no significant change in the cutting position.

2. Conclusion

The service life of PCD tools is generally 10 to 500 times higher than that of cemented carbide tools. PCBN tools are 10 to 100 times more durable than carbide tools. Conventional metal cutters have defects such as chipping, delamination, burrs, burns, etc. when processing certain workpieces. The use of super-hard material tools can not only eliminate the above defects, but also high speed and high efficiency, and low overall cost. With the enhancement of the country's comprehensive strength, with the country's investment in major projects such as large aircraft, Shenzhou series spacecraft, transportation energy, etc., with the continuous improvement of the manufacturing and processing technology of the equipment manufacturing industry, the manufacture of superhard material tools The technical level will be greatly improved, new varieties will continue to emerge, superhard material tools will be developed in the direction of serialization, standardization, specialization, high quality and diversification, and each production enterprise will form its own product features and market positioning. The application fields of superhard material tools will be expanded in the fields of automobile manufacturing, computer and microelectronic components, optoelectronic components, communication equipment, home appliance manufacturing, new ceramic processing, mineral drilling and mining, and aerospace.