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Rroller Bits

1 Learn the meaning of the following words, word-combinations and word groups:

roller, jet, weld, forged wrist, rotate, bearing, cutter, thread, flush, crush, type, use, hole, industry, sectional, fit out, rock-breaking member, outside, tool, top, allow, passage, provide.

2 Read and translate Text 1:

Text 1

In the course of a more than 60-year long history marking the progress in the design of roller bits, use in the drilling practice have found bits with a single, two, three, four and six rollers. Today, however, most widely used are three-roller bits, some of whose type is shown in Fig. 6.1. From among roller bits of other types in use are presently the single-roller cutter ones.

For full hole drilling the industry puts out largely sectional three-roller jet bits (Fig. 6.2) made by welding together three forged sections 3, about whose wrists 5 rotate on bearings 6 and 7 roller cutters 4 fitted out with rock-breaking members. Once the sections are welded together outside (male) tool joint thread 1 is cut at the top end of the bit. To allow for the passage of the drilling fluid the bit is provided with flushing holes 2.

The bits are manufactured with single, two, three and four-cone roller cutters. When the bit rotates clockwise the cutters roll over the bottom hole counter-clockwise and accomplish a complicated rotary motion. As a result, the rock-breaking components of the roller cutters strike the rock and thus crush and chip it off. Therefore, as concerns the principle of rock disintegration, roller bits belong to the class of bits of crushing-chipping action.

Fig. 6,1 Three-roller hit Fig. 6.2 Sectional three-roller jet bit

There exist two patterns of roller cullers arrangement in the bit:

- with the roller cutters axes intersecting the bit axis at one point;

- with the roller cutters axes displaced towards the direction of the bit rotation, parallel to a position in which their axes intesect the bit axis. Such a. displacement of the axes over length is termed positive.

The first design pattern was laid at the basis of the CT, T, T3, TK, TK3, K and OK types of the bit, while bits of the M, M3, MC, MC3, C and C3 types were; constructed by following the second pattern.

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4 Find in Text 1 English equivalents for the following:

широко застосовувати, трирізцеве долото, зварювати, поршневий палець, бур, різьба, буровий розчин, промивати струменем рідини, за годинниковою стрілкою, проти годинникової стрілки, виготовляти, здійснювати, належати до, пересікати, зміщення, дробляче-сколюючий.

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