大钳是钻井过程中起下钻操作的重要工具。二十年代末期,国外开始使用手动大钳,到四十年代才制造出目前广泛使用的B型吊钳,五十年代开始使用动力大钳,从国内外动力大钳的发展情况来看,管径比较规格、扭矩比较小的油管钳和套管钳容易过关。玉门东风油矿的油管钳、大港油田井下攻关队试制的拧扣机等,都已基本过关。而扭矩比较大的动力钻杆钳,目前还处在研制、试验阶段。 Gripper is an important tool for drilling operation during drilling. In the late 1920s, manual tongs began to be used in foreign countries. Until the 1940s, B-type tongs widely used at present were manufactured. In the 1950s, power tongs were used. According to the development of power tongs at home and abroad, Comparison of diameter specifications, the torque is relatively small tubing clamp and casing clamp easily pass. Yumen Dongfeng Oil Pipeline clamp, Dagang Oilfield underground stingy team tried screwing machine, have been basically pass. The torque larger power drill pipe clamp, is still in the research and testing stage.