| Diamond drilling is a kind of advanced way in drilling engineering. But the disabled temperature of Polycrystalline Diamond on PDC (Polycrystalline Diamond Compact) is about 700 ℃, too high temperature will not only make diamond layer and hard alloy layer separate but also make diamond layer burst apart. In addition wearable quality of diamond layer will decline due to plumbaginous tendency. Consequently, during the course of welding, the temperature of diamond layer of PDC should be controlled under 700℃, at the same time the sufficient resist shearing intensity between PDC and bit body should be ensured. Only by this PDC can work long time under the drilling well normally. In a long term, the joint between PDC and bit body widely adopts a technology that high frequency induction heating combines braze welding. But this kind of technology can't control welding temperature and time automatically, it depends on worker's experience and skill. In this condition, it always leads to unstable welding quality. As a result, bit's using life has been affected severely.This paper treats GP30-C3 high frequency induction equipment holded by geological drilling laboratory belongs to Xi'an University of Science and Technology as research object. We cooperated with Xi'an ZhanHong Automatization Corporation, adopted FP93 Fuzzy Self-rectifying temperature PID controller made in Japan, optics fibre temperature sensor and so on, upgraded successfully with digital merer to former high frequency induction equipment and realized closed loop control of welding temperature. Additional, the communications program between personal computer(PC) and PID controller has been designed by VB program language, but it is only limited in laboratorial phase. Since this control system is used in industrial spot, passed through repeating debugging, its control precision is between negative 10℃ and positive 10℃, which satisfies welding technology of...
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