Intermediate frequency hot pressing method: refers to placing the graphite mold for making diamond water drills in the intermediate frequency induction coil. After the power is turned on, due to the induction effect of the intermediate frequency, the graphite mold placed in the induction coil generates eddy current due to the induction of the electric porcelain, which gradually increases the temperature of the graphite mold.
Intermediate frequency hot pressing method: refers to placing the graphite mold for making diamond water drills in the intermediate frequency induction coil. After the power is turned on, due to the induction effect of the intermediate frequency, the graphite mold placed in the induction coil generates eddy current due to the induction of the electric porcelain, which gradually increases the temperature of the graphite mold，The matrix metal mixture containing diamond shrinks and softens. When it is close to the plastic flow state, pressure is applied to make the matrix density close to the theoretical density, so that the matrix is firmly inlaid with diamond and is firmly welded with the steel body. The intermediate frequency induction heating system consists of an intermediate frequency power supply, an intermediate frequency output transformer and an induction coil. Except for very small diameter workpieces, the medium frequency heating system is generally used for heating.
The power frequency resistance heating method is a direct heating method. The input current is transformed into a low-voltage and high-current through a high-current transformer. Usually, the current used is 3-5KA, the voltage is 4-7V, and the capacity of the high-current transformer is generally 50-100KVA. A large current passes through the graphite mold to generate a high temperature, heats the metal powder matrix material in the mold, and the powder material with low melting point components first melts and shrinks. At this time, external pressure is applied to the carcass, so that the carcass material reaches or is close to the theoretical density, and the workpiece is formed. After a little heat preservation, the heating can be stopped.
In-furnace heating and external pressurization method: The process method is to place the mold with the drill steel body and the carcass in a high-temperature heating furnace, heat up to the sintering temperature of the powder material, and then take out the mold immediately after a little heat preservation. Pressurized to the specified size in a nearby press. This method of manufacturing diamond bits must use heat-resistant non-skin steel or cast iron to make abrasive tools, and the sintering temperature of the matrix material should not be too high, otherwise it is very uneconomical.
