➡️ Before run into downhole,the max. installation size of blade shall be bigger the inside diameter,after run into downhole,the blade is pressed to press the spring down,theradial force is given by spring. When hard materials need to be scrapped,scrapping for several times must be done before scrapped to casing inside diameter. The scraper is connected on the low end of drill string,the moving of drill string up and down make an axially feeding in the scrapping operation.
➡️ It is showed in the structure that each spiral blade has two internal and external curved scrapping edges. When the blade is working for reciprocating scrapping,the internal edge and external edge are working in turn,and there is a wider transverse edge band between two scrapping edges stands a cutting and milling action to the cut surface.
➡️ The strap blades are uniform distributed on the scraper so that the returned mud can take the scraped substances away.