| 摘要 |
A casing scraper for cleaning the internal wall of a tube 26 such as a well casing has at least three, rigidly connected, axially and angularly spaced scraper bodies 12, 14, 16 each with a scraping surface 13, 15, 17. The radial dimension of the scraper at each scraping surface is slightly greater than the internal radius of the tube which it will scrape. When the scraper is fully inserted in the tube bore, the scraping surfaces are deflected inwardly and the axial connection 20, 22 between the bodies is accordingly elastically deformed. Th energy stored through this elastic deformation produces a radially outwardly acting force which presses the scraping surfaces 13, 15, 17 against the wall of the tube 26. The eccentric arrangement of the scraping surfaces, and the axial spacing between the surfaces causes the parts of the scraper connecting the scraping surfaces to be placed in bending when the scraper is in place within the tube. The bending of the intermediate parts between the scraping surfaces produces a stress which urges the scraping surfaces into contact with the tube internal surface.
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