The quality of the profiled blade is affected by many factors

The quality of the special-shaped insert is affected by many factors, and the change of various process parameters in the sintering process has the greatest influence on the quality of the special-shaped insert. The composition of the binder/catalyst material, the matrix material, and the particle surface cleanliness, graininess, etc. all determine the performance of the profiled blade.

(1) Selection of substrate Since tungsten carbide cemented carbide has high hardness, good thermal conductivity and toughness, a tungsten carbide-containing carbide containing Co is often used as a PCBN blade substrate. Co as a solvent and binder can significantly improve the sintering degree of CBN and enhance the strength of PCBN, but the content of Co in tungsten carbide hard alloy should not be too high, otherwise it will affect the wear resistance of PCBN inserts and shorten the use of tools. life.

(2) Cleanliness and granularity of CBN grains The surface cleanliness of CBN grains will directly affect the sintering quality of PCBN. Therefore, CBN grains must be treated strictly before sintering to remove moisture from the grain surface. And impurities such as oxides. The method used is mainly heating under vacuum or a reducing gas such as hydrogen or ammonia for 1 to 2 hours. Otherwise, too much impurities will affect the bonding between the CBN-CBN particles and the CBN and the binder, so that the strength of the PCBN blade is reduced and the wear resistance is lowered. The size of the CBN particles not only affects the cutting surface quality of the PCBN tool but also plays a role in the sintering ability of the binder during the sintering of the PCBN. In general, the smaller the CBN particle size, the better the cutting surface quality of the PCBN tool, the better the impact resistance and wear resistance of the tool. Therefore, the hardened steel is processed and high surface quality is required (ie, the PCBN tool is realized). When the car is worn, the CBN particles in the PCBN tool should be taken to a smaller value. On the other hand, since the sintering of the PCBN insert is achieved by the "capillary phenomenon", that is, the penetration of various binder elements into the CBN particles, if the CBN particles are too small, the gap between the CBN particles is reduced, thereby The amount of penetration of the binder element is reduced. Therefore, the CBN particles should be selected to be larger when sintered. Considering the above two factors comprehensively, the mixing particle size should be selected more when CBN is sintered, and different particle size ranges are determined according to the bonding ability of the selected binder.

(3) CBN grain content CBN content has a great influence on the hardness and thermal conductivity of PCBN tools. The higher the CBN content, the higher the hardness of the tool and the better the thermal conductivity. High-content PCBN cutters (typically 80% to 90% CBN) are based on direct bonding between CBNs and have high hardness and high thermal conductivity. These PCBN tools are suitable for processing high hardness alloys and materials with high hardness points in the structure, such as chilled cast iron, heat resistant alloys, etc. At present, such tool shaped blades mainly include BZN6000 of GE Company, AMB90 of Element Six Company, BN100 and BN600 of Sumitomo Electric Company. Low-content PCBN inserts are mostly ceramic binders, which have good heat resistance and are easy to process hardened steel (alloy steel, bearing steel, die steel, carbon steel, etc.), and use the metal softening effect formed by heat retention in the cutting zone for cutting. GE's BZN8100, BZN8200, Element Six's DBC50, Sumitomo Electric's NB300, NB220, and Seco's CBN10, CBN100, CBN150, etc. all fall into this category.

(4) Binder The binder required for CBN sintering:

1 The closer the physicochemical properties are to CBN, the less the weakening of the cutting performance of the PCBN tool after sintering;

2 easy to reach the melting point temperature or have good plasticity at this temperature;

3 has sufficient chemical activity relative to CBN and has catalytic properties for converting hexagonal boron nitride (HBN) to CBN.

At present, the commonly used binders can be classified into metal binders (such as Ni, Co, Ti, Ti-Al, etc.) and ceramic binders (such as TiN, TiC, TiCN, Al2O3, etc.) according to their physical and chemical properties; According to the action, it can be divided into catalysts (such as Al, AlN, AlB2, Si, etc.) and solvent (such as Ti, Ni, Co, TiN, TiC, TiCN, etc.). The type and amount of binder have different effects on the performance of the PCBN insert. Carbide, nitride, carbonitride can improve the chemical wear resistance and impact resistance of PCBN inserts, but too high content will reduce tool hardness and shorten tool life; cobalt is the most commonly used binder to improve CBN sintering. Titanium sintering time; Ti ceramic binder can improve the toughness of PCBN insert; aluminum and aluminum compounds can react with CBN particles and other binders to make CBN particles bond more firmly and improve tool wear resistance; The mixture with Al, AlN and AlB2 is an effective catalyst for the conversion of HBN to CBN. The addition of a small amount of Al and Si in the ceramic binder can also enhance the bonding between CBN to form a continuous ceramic phase; The PCBN composite sheet as a binder is highly conductive and suitable for cutting with a low-cost electric spark.

Due to the different binders, PCBN inserts now tend to have two characteristics: one is high wear resistance (high content CBN, catalytic binder), and the other is good impact resistance (low content CBN) , ceramic binder).