Abstract: Various structures of open-head type drilling string power tongs are compared,with their advantages and disadvantages analyzed,laying particular stress on the Q10Y-M hydropneumatic power tong and its new and unique features as that the rotary tong and the back tong are built in one body; the tong body is stationary while the tong head is floating,and also the inclusion of a two-stage reducer for the pneumatic gear,the shifting of gear without stopping operation,the hydraulic-pneu-matic control system and the resetting mechanism ete.Its excellent performances in oit field drilling relative to personal safety,reliability of operation,relief of crew from fatigus,high operating efficiency,reduced bending of drill-pipes,controllable make-up torque,ability in coring and handling emergencies etc.are described.As a key to the designing of clamping mechanism,the concept of the ration of angential force to radial force is introdoced,together with its varistions during the tentire process of clamping,It serves as the theoretical basis for designing a portable and reliable clamping device.A simple methed for calculating the closed-gear chain,essential to the power tong is also proposed.In the last part of the paper,the technical and economic effectes of the Q10Y-M hydropneumatjc power tong aer examined.

摘要： Q10Y-M液气大钳系开口钻杆动力钳,它主要适用于普通深井钻机的机械化上卸扣作业,也可装在半自动化或全自动化钻机上.操作只需一人,不用猫头、吊钳和旋扣链(或旋绳).该液气大钳采用转钳(浮动钳头)和背钳一体结构.液气大钳安全省力,能提高操作速度,减少钻杆弯曲,控制上扣扭矩,能满足取心、处理事故等作业要求.

关键词: 液气大钳, 结构设计, 钳头, 夹紧机构, 动力钳, 浮动体, 接头, 开口钳, 方案, 制动扭矩