| 摘要 |
A device which is expandable to engage the interior of a tube, for example t he casing of an oil well, comprises first and second (3) tubular members in partial telescopic engagement with each other, the first tubular member having an en d region which is received on the second tubular member and which is expandable radially outwardly to engage the interior of the tube. The second tubular member (3) has tapered regions (12,13,14,15) which, when forced into the end region, will cause radial expansion of the end region. The taper angle of the second tapered zo ne (13) is less than the taper angle of both the first tapered zone (12) and the third tapered zone (14). The fourth tapered zone (15) preferably has a taper angle which is greater than that of the second tapered zone and less than that of the third tapered zone . In one embodiment, the tapered zones (12,13,14,15) have respective taper angles of 15.degree.,1.degree., 5.degree. and 1.25.degree..
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