RU2330929C2 - Rock bit installation method - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention pertains to drilling technology, and particularly to the method of installing a rock bit. The method involves the following stages: the legs and rock roller bits are numbered, diameter and linear dimensions of bearing pathways are measured, recorded into a computer and using a special computer program, the "leg-rock roller bit" pairs are selected for each section and drilling bit section. The sections are gathered and welded together. For each drilling bit section, the optimum difference in radial and axial gaps are individually calculated based on the criterion of minimum maximum contact pressure in the support. The "leg-rock roller bit" pairs and drilling bit sections which have minimum deviation of these parameters from corresponding optimum values are then chosen.

EFFECT: increased durability of the support of the drill bit, its increased penetration due to equal distribution of contact loads on the support components.

11 dwg

Description

The invention relates to drilling equipment, namely to drill bits.

A known method of assembling cone bits with random selection of paws and cones and layout bits from sections [1].

The disadvantage of this method is that the dimensions of the paws and cones are randomly selected within the tolerance field. This leads to significant differences in the values of the clearances in both radial and thrust bearings of the bearings. When the bit contacts the face, the corresponding bearing working surfaces come into contact at the same time. In this case, part of the bearings immediately starts operation, and the other part begins to work only after wear of the first ones by the size of the gap difference. This leads to overloads of the former, a significant increase in specific loads and premature failure of the support. In addition, the random arrangement of bits from sections with different clearances in the bearings leads to significant differences in sections of one bit in assembly quality, limits the resource of the bit of the worst of the selected sections.

A known method of assembling bits [2], in which before assembling the cone bit, including the assembly of the individual sections of the legs and cones and connecting the sections together by welding, the paws and cones of each type are numbered, the diametric and linear dimensions are measured in the supports of the paws and cones, and they are entered in a computer and using a specially designed program, first, for each type and number of cones used in the bit, the paw with the smallest difference of the radial and linear gaps ΔR and ΔН is selected, and then sections with minimal differences are selected for each bit ΔR and ΔН.

The disadvantage of this method is that during assembly, structural differences (shape and dimensions) of the large and small supports are not taken into account, which does not ensure a completely uniform distribution of contact loads in the support of each section. In addition, differences in the magnitude and direction of the total loads on different sections of the bit are not taken into account.

The aim of the present invention is to increase the resistance of the support of the bit, increase its penetration by reducing the maximum contact loads based on ensuring the most even distribution of loads across the bearings both within the support of a separate section and throughout all sections of the bit.

The above goal is achieved by the fact that before assembling the cone bit, including the numbering of the paws and cones, measurements in the supports of the paws and cones of the diametric and linear dimensions of the bearing tracks: D is the diameter of the large paw bearing, d is the diameter of the small paw bearing, D _w is the diameter of the large roller cone bearing, d _ш - diameter of a small roller cone bearing, Н - distance from the axis of the ball track of the paw to the thrust heel, h - distance from the axis of the ball track to the thrust shoulder, N _sh - distance from the axis of the ball track to the thrust bearing, h _w - distance from axis ball track to the thrust collar, entering measurement data into a computer, and using a specially designed program, select the “leg-cone” pairs for each section and sections for the chisel, collect sections from the legs and cones and weld them together, for each i-section bits calculated by a computer program, and the optimum radial linear difference ΔR _iopt and gaps? H _iopt, determined by minimizing the difference between the contact pressures in the radial and thrust bearings pins Dp _Ri → min and the minimum of the absolute value of the difference Comte tnyh pressure in the thrust and abutment heel turners trunnion Dp _Hi → min, and then for each selected bit sections with minimal radial clearance differences differences ΔR _i and line gaps? H _i from the respective optimum values collected for each section;

where i is the bit section number;

Δр _Ri is the absolute value of the difference of contact pressures in the large and small radial axle bearings;

Δp _Hi is the absolute value of the difference of contact pressures in the thrust shoulder and the persistent heel of the pin.

Such a procedure for assembling bits makes it possible to solve the problem of increasing the stability of their bearings and sinking by distributing the face reaction most evenly over the working surfaces of the bearing (radial and axial) bearings of each of the bearings and, thus, reducing the maximum specific loads in the contact areas of the support elements. The sections of the bits are selected with the parameters ΔR and ΔН, as close as possible to the optimal values calculated for each section, which ensures the highest possible build quality of the sections and, as a result, the increased resistance of their supports and bits in general.

Comparison with the prototype shows that the inventive method of assembly is characterized in that the sections of the bits are selected not with the minimum values of the parameters ΔR and ΔН, but with the optimal ones, determined for each section individually in accordance with the current load on this section; when arranging bits, sections for one bit are selected with minimal differences in ΔR and ΔН not between themselves, but from the corresponding optimal values, ensuring the highest possible quality of their assembly. Thus, the inventive method of assembling bits meets the criteria of the invention of "novelty."

Figure 1 shows the pin paw of the bit; figure 2 - diagram of the support cone bits; on figa-3E - contact options of the working surfaces of the trunnion and cone i-th section of the bit under the action of the reaction of the face G _i and the distribution of contact loads on the elements of the trunnion.

On the pin 1 (Fig. 1) there are: a radial surface of a large plain bearing 2 of diameter D, a radial surface of a small plain bearing 3 of diameter d, a thrust plain bearing (thrust shoulder) 4, an end plain bearing (thrust heel) 5 and a ball treadmill 6 lock bearing. The sliding surfaces 4 and 5 are located respectively at a distance h and H from the axis of the ball treadmill.

On the cone 7 (2) has: a radial sliding bearing surface of the large diameter D _w 8; the radial surface of a small plain bearing 9 with a diameter d _w ; thrust plain bearing (thrust shoulder) 10; end plain bearing 11; ball treadmill 12 lock bearings. Surfaces 10 and 11 are located from the axis of the ball treadmill, respectively, at a distance of h _W and N _W.

Each i-th cone (Fig. 3) during operation has its own load from the face reaction G _i , which is distributed among the radial and thrust bearings, depending on the values of the difference between the radial clearances

and linear gaps

At zero values of ΔR and ΔН, the contact loads on the radial and axial bearings, respectively, are distributed unevenly on their surfaces due to design differences, which does not provide optimal contact between the working surfaces of the bearings, leads to overload of one of them and premature failure of the bit support.

If under the action of the load G _i , the surfaces 2 and 8 of the large and the surfaces 3 and 9 of the small radial plain bearings come into contact and ΔR _i <ΔR _iopt , then the radial component of the load G _i creates the largest contact pressure p _i in the large plain bearing ( figa); if ΔR _i > ΔR _iopt , then the radial component of the load G _i provides the greatest value of p _i in a small sliding bearing (Fig.3B); if ΔR _i = ΔR _iopt , then the radial load is distributed over both radial bearings so that the contact pressures in these bearings are equal (Fig.3B).

Similarly, if the surfaces 5 and 11 of the end bearing and the surfaces 4 and 10 of the thrust _collar come into contact and ΔН _i <ΔН _iopt , then the axial component of the load G _i creates the greatest value of the contact pressure p _i in the end bearing (Fig. 3G) ; when ΔН _i > ΔН _{iopt, the greatest} contact pressure acts on the thrust collar 4 (fig.3D); at ΔН _i = ΔН _{iopt, the} contact pressure is evenly distributed over two thrust bearings (Fig. 3E), which allows to reduce the maximum contact loads on the surfaces 4 and 5 of the journal, increase the stiffness of the support, reduce the skew angle and increase the resistance of the support.

In the process of assembling bits according to the proposed method, it is necessary to fulfill the conditions:

difference of radial clearances

difference of linear gaps

The closer the difference values of the gaps ΔR _i and ΔН _i to the corresponding optimal values, the lower the maximum value of the contact load p _i in the support of the i-th section and, therefore, its resistance is higher. Within one bit, sections are selected with minimal differences in the differences between the radial ΔR _i and linear ΔН _i gaps from the corresponding optimal values.

Assembly of bits according to the proposed method is carried out in the following order. Paws and cones of each of the N types are numbered. On the pins of the paws, the diameters D, d and the linear dimensions H, h are measured (see FIG. 1), on the cones, the diameters D _W , d _W and the linear dimensions H _W , h _W are measured, these parameters are entered in the computer in tabular form and with using a specially designed program, according to formulas (1) and (2), for all possible combinations of paws and cones, the differences between the radial clearances ΔR _i and linear clearances ΔН _i are calculated and sets of cones are selected for each bit (No. 1, No. 2, ..., №N) and paws, which satisfy the condition (3), and at a fixed level and the condition ΔR _i (4), said bit within a section irayut with minimal differences from the difference in the gaps: ΔR _i and ΔR _iopt from? H? H _i from _iopt. Based on the calculation results, a table is formed where for each number of the collected bit the numbers of paws and cones for each of the N sections are indicated. The bits in the table are arranged in increasing order of differences ΔR _i from ΔR _iopt and ΔН _i from ΔН _iopt , i.e. in order to reduce the quality of assembly of bits. In accordance with the table, separate sections are completed and drill bits are assembled from sections.

For the supports of bits with roller bearings, the difference of the radial clearances ΔR is calculated by the formula

where D _p , d _p are the diameters of the large and small rollers.

The method described above was tested when assembling 20 bits with a diameter of 215.9 mm.

Figure 4 presents a distribution diagram of the average bit resistance over 3 ranges of maximum deviation in the bit ΔR _i from ΔR _iopt .

From the analysis of the diagram it follows that the minimum average deviation of bits - 253 thousand revolutions corresponds to the minimum deviations (range 0 ÷ 0.004 mm); the second deviation range (0.004 ÷ 0.008 mm) corresponds to 205 thousand revolutions, which is 19% lower compared to the first; the third range (0.008 ÷ 0.012 mm) corresponds to an average resistance of 159 thousand revolutions, which is 37.2% lower than for the 1st range. It follows that the main indicator of the quality of the bit - its durability - significantly decreases with increasing maximum deviation of the parameter ΔR _i from the optimum.

Figure 5 presents a diagram of the distribution of the number of bits over the same ranges of maximum deviation in the bit ΔR _i from ΔR _iopt for two methods of assembly.

From the diagram it follows that in the 1st range falls 10 bits (50%) collected by the proposed method, and 8 bits (40%) collected using the basic method (2); 6 bits (30%) and 5 bits (25%) respectively fall into the 2nd range; in the 3rd range - respectively 4 bits (20%) and 7 bits (35%). It follows that the quality of assembly of bits in the parameter ΔR _i to the described method is much higher than for the base procedure of selective bits computer assembly.

Figure 6 shows a diagram of the distribution of the number of bits over 3 ranges of maximum deviation in the bit ΔН _i from ΔН _iopt .

From the analysis of the diagram it follows that the first range (0 ÷ 0.001 mm) includes 8 bits (40%) in the case of assembly by the proposed method and 6 bits (30%) for the basic assembly method; in the 2nd range (0.001 ÷ 0.002 mm) 7 bits (35%) and 6 bits (30%) respectively fall; in the 3rd range - 5 bits (25%) and 8 bits (40%), respectively. Therefore, the quality of the assembly of bits according to the parameter ΔН _i using the proposed methodology is higher than with the basic technique of selective computer assembly of bits.

Thus, drill bits assembled according to the proposed method, compared to those assembled using the basic selective computer assembly method, have higher assembly quality in two complex indicators - the differences between the radial ΔR _i and linear ΔН _i clearances in the supports, which provides a significant increase in the stability of the supports drill bits and penetrations.

The present invention can be used in enterprises producing roller cone bits.

Information sources

1. Sultanov S.G. Progressive technology of oilfield engineering. - M.: "Mechanical Engineering", 1969, p.111-132.

2. RF patent No. 2184203, Е21В 10/20, dated June 27, 2002, bull. Number 18.

Claims (1)

The method of assembling a cone bit, which consists in the fact that the paws and cones are numbered, measure the diametrical and linear dimensions of the bearing tracks in the supports of the paws and cones: D - diameter of the large paw bearing, d - diameter of the small paw bearing, D _w - diameter of the large cone bearing, d _w is the diameter of the small cone roller bearing, N is the distance from the axis of the ball path of the paw to the thrust heel, h is the distance from the axis of the ball path of the paw to the thrust shoulder, N _w is the distance from the axis of the ball path of the cone to the thrust bearing, h _w is the distance from the axis ball up cones are cut to a hard shoulder, put them into a computer and using a specially designed computer program they select the “leg-cone” pairs for each section and section for the chisel, collect the sections and weld them together, characterized in that for each i-th section bits calculate the optimal differences of the radial and linear gaps ΔR _iopt and ΔН _iopt , determined from the conditions of the minimum absolute value of the difference in the design contact pressure in the large and small radial bearings of the journal Δp _Ri → min and the minimum absolute value of the difference even contact pressures in the thrust shoulder and the thrust fifth of the trunnion Δp _Hi → min, and then for each bit sections are selected with minimal differences in the differences between the radial clearances ΔR _i and the linear clearances ΔH _i from the corresponding optimal values for each assembled section.

Images