金刚石钻进是钻探工程中一种比较先进的钻进方法。但是金刚石钻头上聚晶金刚石复合片PDC（Polycrystalline Diamond Compact）中聚晶金刚石层的热稳定失效温度为700℃，超过失效温度，金刚石层与硬质合金衬底易分层，并且金刚石层易崩刃，金刚石层的耐磨性也将因石墨化而下降。因此，焊接过程中PDC金刚石层的温度要控制在700℃以下，并要求焊接后PDC与钻头钢体间有足够的抗剪强度，以使PDC能在井下长期工作不失效。长期以来，PDC与钻头体间的连接大都采用高频感应—火焰钎焊相结合的焊接技术，这套方法不能对焊接温度及焊接时间进行自动控制，而是由焊接技术人员凭经验及熟练程度来操作，焊接质量具有很大的随意性，从而影响钻头的使用寿命。 本论文以西安科技大学地质钻探实验室的GP30—C3型高频感应加热设备为研究对象，与西安展宏自动化发展有限公司合作开发,采用日本岛电公司生产的FP93模糊自整定PID温控仪、光纤温度传感器等对原有的高频感应加热系统进行了数字化改造，实现了焊接温度的闭环控制，并采用VB语言编程实现了PC机对下位机温控仪的远程监控（限于实验室模拟）。此控制系统投入现场以来，经过反复的调试，控温精度可达±10℃，完全满足PDC钻头的焊接工艺要求。 感应加热系统是一个大滞后、非线性、时变的比较复杂的系统，用一般的PID控制会导致控制作用不及时，引起系统的超调和振荡，难以获得良好的控制效果。本论文采用Fuzzy控制和PID控制并联对系统进行控制，根据被控温差大小对两种算法进行切换。实践表明，这种算法既能保证控制系统的稳定性，又可获得高的控制精度。本论文还对Fuzzy自整定+PID控制算法的原理进行了细致的研究。 在完成控制系统的开发之后，我们又利用此系统对影响PDC钻头焊接性能的焊接温度、升温速度以及保温时间这三相因素进行了科学周密的正交试验研究。一方面考核了系统的可靠性，另一方面还摸索出了优化的焊接工艺参数组合。

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 PDC bit fully． The control system of induction heating is complex full of hysteresis，non-line and variability．Toward this condition，common PID control arithmetic can’t control in time，it will lead to error and surge，as result ，it is very difficulty to gain a good control effect． Aim at these localization ，Fuzzy Self-rectifying plus PID control are adopted to automatic control system，according to error of temperature，two kinds of arithmetics are switched now and then．Practice indicates this way can ensure excellent stability and precision of the control system．Besides，the principle of Fuzzy Self-rectifying plus PID control is researched in detail in this paper． Having finished exploiture of the automatic control system，we carried out scientific and careful research in laboratory with welding temperature，heating speed and heat preservation time，which affect welding quality of PDC bit evidently．One side dependability of the control system is verified，the other side a kind of optimal manufacture technology of PDC bit is fished out．