RU2179620C2 - Drag drill bit - Google Patents

Abstract

FIELD: rock-breaking tools. SUBSTANCE: drag drill bit has body with central hole, blades with plug-in cutting picks, flexible branch pipe attached with upper end to body. Lower end of flexible branch pipe is fitted with extension piece and weight coming in the form of bushing. Upper part of one of blades in space of central hole has either geometrical form or geometrical dimensions different from other blades. Operation of one of blades differing from other blades leads to formation of force by flow of flushing fluid that deflects flexible branch pipe. Coriolis and centrifugal forces will act on branch pipe in process of rotation of drill bit. As result of action of these forces lower end of branch pipe will run on surface of one of blades. Under action of flows repelled from surface of blade flexible branch pipe will deviate from surface of blade and so on. Lower end of branch pipe will make complicated motion relative to drill bit. Due to this motion of lower end of flexible branch pipe flow of flushing fluid will be directed in sequence to one or another sector and so forth. As result sliming of interpick spaces is prevented which increases efficiency and reliability of operation of drag drill bit. EFFECT: increased efficiency and reliability of operation of drag drill bit. 4 dwg

Description

 The invention relates to a rock cutting tool, namely to drilling paddle bits of cutting-chipping action, and are used when drilling wells.

 Known drill blade cutting and shearing action, comprising a housing with a Central hole, the blades with inserted teeth, a flexible pipe fixed with the upper end coaxially to the housing, a diverter in the form of a hemisphere, the diverter rigidly mounted on the blades coaxially with the housing with the possibility of a gap between the lower end flexible pipe and hemispherical surface of the deflector (1).

 The disadvantage of this bit is that the energy of the flushing liquid is used inefficiently to create the largest alternating pressure drop between the sectors at the bottom of the well (assume: a sector is the bottom surface formed between two adjacent bits of the bit).

 This bit design is symmetrical. The presence of a diverter made in the form of a hemisphere and mounted along the axis of the bit on the blades does not lead to asymmetry in the design of the bit.

 Thus, the oscillation of the flexible pipe will occur due only to fluctuations in the fluid flow rate in the pipe itself (turbulent flow mode).

 The turbulent mode of fluid flow is characterized by a high frequency and a small amplitude of fluid oscillations perpendicular to the flow.

 In this regard, the oscillation of the lower end of the flexible pipe will occur with a small amplitude and a high frequency. Therefore, the magnitude of alternating pressure drop and fluid velocity in the subscapular space between sectors will be insignificant, which in turn leads to poor-quality cleaning of interdental spaces. Poor cleaning of the interdental spaces impairs the cooling of the inserted teeth. This reduces the efficiency and reliability of the blade.

 The aim of the invention is to increase the efficiency and reliability of the blade bits cutting-shearing action by efficiently using the energy of the flushing fluid by increasing the amplitude of the lower end of the flexible pipe.

 This goal is achieved by the fact that the lower end of the flexible pipe is equipped with a nozzle and a load made in the form of a sleeve, and the upper part of one of the blades in the cavity of the central hole has either a geometric shape or geometric dimensions different from others.

 By performing the upper part of one of the blades in the cavity of the central hole, which is different from the others, asymmetry is introduced into the design of the bit.

 When the bit is operated at the bottom of the well due to asymmetry in its design, a deflecting force arises acting on the flexible pipe. This force arises as a result of the effect of reflected flows of drilling fluid from the bottom of the well and the surfaces of the blades and the central hole on the flexible pipe.

 As a result of the rotation of the bit, an additional centrifugal force arises, acting on the flexible pipe, due to the installation of a nozzle and a load made in the form of a sleeve on its lower end. As a result of the action of these forces on the flexible pipe, its lower end deviates by a large amount from the axis of the bit in comparison with the prototype. Due to the rotation of the bit and the movement of the flushing fluid along the flexible nozzle, the Coriolis force acts on the latter. In this case, the Coriolis force will be directed opposite to the rotation of the bit. As a result of this force, the lower end of the nozzle will run onto the surface of one of the blades. Under the action of flows reflected from the surfaces of the blade to the lower end of the flexible pipe, the latter deviates from the surface of the blade, etc.

 Thus, the lower end of the flexible pipe will describe a complex movement. Due to this movement of the lower end of the flexible pipe, the flow of washing liquid will be directed sequentially oriented to one sector, then to the other, etc., but the amplitude of the lower end of the flexible pipe of this bit will increase compared to the prototype, since the proposed bit asymmetry and additional load in the form of nozzles and sleeves.

 Due to the increase in the amplitude of oscillation of the lower end of the flexible pipe, the flushing fluid flowing out of the flexible pipe will be directed to certain sectors, then to the other, and so on.

 In this case, ejection of the flushing fluid will be sequentially oriented from other sectors, which helps to reduce the pressure in these sectors. As a result of this, the values of alternating pressure difference between sectors and the speed of the washing fluid in the interdental space increase, which in turn leads to better conditions for cleaning the interdental spaces and cooling the insert teeth of the bit.

 As a result of this, the efficiency and reliability of operation is increased due to the preservation of the insertion teeth.

 Figure 1 shows a bottom view of the drill blade; figure 2 is a section aa in figure 1; figure 3 is a section bB in fig. 2; figure 4 - section bb in fig. 2.

 The blade bit consists of a housing 1 (see figure 2), blades 2 with insertion elements 3, a flexible pipe 4 with a nozzle 5 and a sleeve 6, mounted in the housing 1 along the axis of the bit with a washer 7 and a nut 8. The lower end of the flexible pipe 4 with a nozzle 5 and a sleeve 6 is located above the blades 2. Moreover, the upper part of one of the blades in the cavity of the Central hole, for example, is made in a T-shape (see figure 1,2,3). In addition, the width of the upper part of this blade in the cavity of the Central hole is greater than that of other blades.

 The blade bit works as follows.

 During the drilling of the well, the blade bit rotates, the flow of flushing fluid passes through the flexible pipe 4 with nozzle 5 and is sent to the bottom of the well. In this case, the lower end of the flexible pipe 4 with the nozzle 5 and the sleeve 6 deviates in the opposite direction from the blade, which has a large upper area, due to the action of the hydrodynamic forces of the reflected flows of washing liquid from the bottom, the surfaces of the blades 2 and the central hole.

 As a result of the rotation of the bit and the movement of the flushing fluid along the flexible pipe 4, the centrifugal and Coriolis forces act on the latter. Centrifugal force increases the deviation of the lower end of the flexible pipe 4 with the nozzle 5 and the sleeve 6 from the axis of the bit. The Coriolis force is directed against the rotation of the flexible pipe 4. As a result of the action of this force on its last lower end, it will run onto the surface of one of the blades 2. Under the action of reflected flows from the surface of this blade, the lower end of the flexible pipe 4 will deviate from the blade, etc.

 Thus, the lower end of the flexible pipe 4 with the nozzle 5 and the sleeve 6 will describe the complex movement relative to the bit and bottom of the well. Due to this movement of the lower end of the flexible pipe 4, the flow of flushing fluid will be directed sequentially oriented to one sector, then to another, etc. As a result, in the interdental spaces, the movement of the flushing fluid will constantly change its direction, which in turn leads to the exclusion of sludge interdental spaces, to improve the cooling conditions of the inserted elements, to the effective and reliable operation of the blade bit.

Sourse of information
1. Patent R.F. 2078191 "Drill bit", registered 04/27/1997

Claims (1)

 A cutting-chipping drill bit containing a body with a central hole, blades with insert teeth, a flexible pipe fixed with its upper end to the body, characterized in that the lower end of the flexible pipe is equipped with a nozzle and a load made in the form of a sleeve, with a geometric shape or the geometric dimensions of the upper part of one of the blades in the cavity of the Central hole are made different from the shape and size of the upper part of the other blades.

Images