钻井中所下的套管在发生卡钻事故时，常因挤夹过紧而无法起出，必须用分段取拔法来处理。在分段切刮被挤夹之岩心管和套管的方法上，通常都采用二把或三把锋钢刀片的水压切管器来进行。就目前的使用情况来看，这种切管器还不能令人完全满意，因为它的构造复杂，制作困难，并且在使用时常发生掉刀子、 Drilling casing in the event of a stuck pipe accident, often due to squeeze clamp too tight and can not be played out, must be used to deal with the segmented extraction method. The method of sectioning and scraping the core and casing pinched together is usually carried out by using two or three hydraulic cutters of steel blades. In the current state of use, this type of pipe cutter has not been completely satisfactory because of its complicated structure, difficulty of manufacture, and frequent use of knives,