RU2332551C2 - Method of rock-roller bit assembly - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to rock-destroying tools, particularly, to rock-roller bits. The rock-roller bit assembly method comprises the following jobs, i.e. the bit sections are preliminary assembled, each section being composed of a rock cutter, a set of large and small rollers fitted on the support bracket journal large and small races. Note here that the set of rollers for the said races is assembled using the minimum designed values of annular gaps Xa, the difference between them being also kept up minimum. The rollers for the aforesaid races are gathered from different selective groups with an optimum assembly structure m defined by the substitution group of rollers alternating as follows, i.e. D_srD_maxD_min/d_maxd_srd_min, where D_max, D_sr and D_min are diameters of the large rollers taken from the first, second and third selective groups, and d_max, d_sr and d_min are diameters of small rollers taken from the first, second and third selective groups. Now, the set of large rollers is turned relative to the set of small rollers through the designed angle φ, the mark made on the support bracket journal base making a turn reference point.

EFFECT: higher quality and accuracy of the rock-roller bit.

1 tbl, 5 dwg

Description

The present invention relates to drilling equipment, namely to drill bits, in the construction of which there are multi-row roller bearings, and is used in the oil industry and mining.

A known method of assembling movable joints, described in the reference book "Friction, wear and lubrication": in 2 books. / Ed. I.V. Kragelsky, V.V. Alisina. - M.: Mechanical Engineering, 1978. 400 p. (p. 122), which is based on the dependence of the resource on build quality. The resource is estimated at the assembly stage by the statistical parameters of the annular gaps of the movable joints, which constitute a random value of deviations of the actual dimensions, shape and location of the surfaces of the mating parts

- дисперсия функции зазоров на этапе сборки, мкм²;

- дисперсия функции скорости изнашивания, (мкм/ч)²; Т - ресурс изделия, ч; И_max - допустимая величина износа, мкм; Х_a - математическое ожидание функции зазоров, мкм; γ - математическое ожидание функции скорости изнашивания, мкм/ч.where U _α is the quantile of the normal distribution;

- the dispersion of the gap function at the assembly stage, μm ² ;

- variance of the wear rate function, (μm / h) ² ; T - product resource, h; And _max is the allowable amount of wear, microns; X _a is the mathematical expectation of the gap function, μm; γ is the mathematical expectation of the wear rate function, μm / h.

The result of the calculation according to dependence (1) is the selection of the parameters of the annular gaps (Figure 5) within the possible permutations of symmetrical parts within the same selective group. Providing minimal annular gaps allows to improve the operational quality of the supports and, in particular, to increase the adaptability of the rollers to external load cycles.

However, this dependence does not take into account the impact on the resource of the structural features of the roller bearings, the kinematics of the interaction of the mating parts, and the group interchangeability method when achieving the accuracy of the closing link of the multi-link dimensional chain does not guarantee a stable result when operating bits. For these reasons, the resource of roller bearings, calculated according to the actual diametrical dimensions of the rollers and treadmills of the roller cutter and the pin paw axle [1], gives an estimated value of 293 hours, compared with 30 hours obtained from processing statistics of experimental data of bench testing of bits .

The disadvantage of this method is that without taking into account the above factors affecting the statistical parameters of the process of interaction of the mating parts, it is not possible to use the dependence (1) and based on it to develop an algorithm for choosing the optimal parameters for the assembly of roller bearings.

Also known is a method of computer selection, which reduces the influence of a random factor on the parameter of diametrical clearances when assembling multi-row roller bearings. This method consists in the following: the paws and cones are numbered, the diametric and linear dimensions are measured in the supports of the paws and cones, they are entered in a computer and, using a special program, the paws with the same difference of extreme radial and linear gaps are selected for each cone number [2].

The disadvantage of this method is that it does not take into account the probabilistic characteristics of the size range of sets of rollers, which have a significant effect on the annular gaps. Therefore, this method does not exclude the dominance of a random factor in the dispersion of the actual sizes of the rollers belonging to the small and large roller tracks. This is due to the fact that a kit assembled from rollers of one selective group gives a spread in the diametrical clearance ω _AΔ = 0.06 mm, determined by the following relationship

where δ _Ai is the tolerance of the diametric size of the i-th selective group of rollers, equal to 0.004 mm; N - the number of rollers in the kit (on average 15 pcs.).

The influence of this random factor on the quality of roller bearings assembled by computer was not taken into account.

In addition, the computer assembly method does not take into account the random components of the relative positions of the rollers relative to the cone teeth and the sets of rollers among themselves, which affect the accuracy of calculating the resource of the support.

The technical result of the present invention is to reduce the influence of random factors on the values of the annular gap and to reduce the error of the calculated values of the resource supports.

The technical result is achieved in that the rollers of the large and small roller tracks complement of different selective groups with optimal structure assembly _{D sr D max D min / d} max d sr d min, check the value of gaps in complete with measured diametral dimensions of treadmills, exercise reversal sets of large rollers are relatively small by the estimated angle φ, the reference point for the turn is the mark applied on the base of the paw pin.

In the proposed method for assembling roller bearings, an algorithm is developed using which (by exhaustive search) from the admissible set of all options for picking rollers, one is selected whose assembly ensures the maximum value of the estimated resource. This algorithm is based on the design scheme of the resource of movable joints (1) and takes into account the design features of roller bearings and the cyclic nature of operational loads.

The absence of a separator in the roller support does not violate the cyclicity of the interaction process of the rollers, which proves the fulfillment of the cyclic condition. This circumstance indicates the property of repeatability of the trajectories of the rollers interacting with the roller tracks for each complete revolution of the cone. At a constant speed of rotation of the bit, this condition provides the property of stability of the operating cycles of heavily loaded roller bearings.

Given this property of repeatability of roller paths, the algorithm for calculating the resource of two-row roller bearings is represented by the dependence

Where

- функционал дисперсии зазоров роликовой опоры, рассчитанный в зоне упругопластических деформаций в зависимости от структурной составляющей сборки m и угловой переменной расположения двух комплектов роликов между собой φ, мкм²;

- дисперсия функции скорости изнашивания роликовой опоры, (мкм/ч)²; Т - ресурс опоры, ч; И_max - максимально допустимый зазор между роликами, обеспечивающий работу долота без заклинивания опор, мкм; с_a,i - коэффициент вариации функции сборочных зазоров с учетом способа сборки; Х_a - значение рассеивания замыкающего звена комплектов роликов относительно действительных размеров роликовых дорожек шарошки, рассчитанное по методу полной взаимозаменяемости, мкм (фиг.1); с_γ,j(m, φ) - коэффициент вариации функционала скорости изнашивания роликовой опоры в зависимости от структурной составляющей сборки m и угловой переменной расположения комплектов роликов и комплектования рядов зубков в шарошке φ (фиг.2), устанавливающий связь внешних циклов нагрузок с внутренней структурой сборки роликовых опор; m - структурная составляющая сборки соединений комплектов роликов большой и малой роликовых дорожек, которая определяется группой подстановок роликов, установленных в определенной последовательности с различными значениями действительных диаметральных размеров, например, 〈D_srD_minD_max〉/〈d_srd_mind_max〉; К(φ) - структурный коэффициент внутренней структуры сборки роликов большой и малой роликовых дорожек опоры, который равен отношению числа благоприятных исходов n₊ к числу неблагоприятных n_- при заданном φ; γ - математическое ожидание скорости изнашивания, определяется по измеренной величине износа роликов за время ресурсных испытаний, мкм/ч.U _α is the quantile of the normal distribution with α level of confidence;

- the functional dispersion of the gaps of the roller bearings, calculated in the zone of elastoplastic deformations depending on the structural component of the assembly m and the angular variable location of the two sets of rollers between each φ, μm ² ;

- variance of the function of the wear rate of the roller bearings, (μm / h) ² ; T - resource support, h; And _max - the maximum allowable gap between the rollers, ensuring the operation of the bit without jamming the supports, microns; с _{a, i} - coefficient of variation of the function of assembly gaps, taking into account the assembly method; X _a - the dispersion value of the closing link of the sets of rollers relative to the actual dimensions of the roller tracks of the roller cutter, calculated by the method of complete interchangeability, microns (figure 1); with _{γ, j} (m, φ) is the coefficient of variation of the functional of the wear rate of the roller bearing depending on the structural component of the assembly m and the angular location variable of the sets of rollers and the acquisition of rows of teeth in the roller cutter φ (Fig. 2), which establishes the relationship between the external load cycles and the internal assembly structure of roller bearings; m is the structural component of the assembly of the joints of the sets of rollers of the large and small roller tracks, which is determined by the group of substitutions of the rollers installed in a certain sequence with different values of the actual diametrical dimensions, for example, 〈D _sr D _min D _max 〉 / 〈d _sr d _min d _max 〉 ; K (φ) is the structural coefficient of the internal structure of the assembly of rollers of the large and small roller tracks of the support, which is equal to the ratio of the number of favorable outcomes n ₊ to the number of unfavorable n _- for a given φ; γ is the mathematical expectation of the wear rate, determined by the measured value of the wear of the rollers during the life tests, μm / h.

The resource of the support is estimated by the value of the roots T _max and T _{min of} equation (3), taking into account group properties

After substituting the values of the variable parameters of the exchange interaction of the roller groups of the large and small roller tracks K (φ), as well as the effect of the tooth group with the roller group c _{γ, j} (m, φ) in the objective function (3), the resource is calculated using the developed MS Excel program. The table selectively presents the values of the estimated life T _{p of a} multi-row roller support depending on the angle of rotation of the sets of rollers relative to each other φ and the structure of the sets of rollers of the large and small roller tracks of the support m.

Predicted bit support resource Structures of roller sets of large and small roller tracks Swivel angle of the roller sets Estimated resource of support m φ, deg. T _r , h D _sr D _min D _max / d _min d _max d _sr twenty 45.71 D _max D _sr D _min / d _max d _sr d _min twenty 41.25 D _sr D _min D _max / d _sr d _min d _max twenty 29.14 D _sr D _min D _max / d _min d _max d _sr 70 34.24 D _min D _max D _sr / d _sr d _min d _max 70 28.51 D _sr D _min D _max / d _sr d _min d _max 70 21.83

и

- диаметральный зазор в большой и малой роликовой дорожке;

и

- кольцевой зазор в комплектах роликов большой и малой роликовых дорожек.Figure 1 shows the scheme of completing the rollers of the large and small roller tracks, taking into account one of the variants of the structure m; figure 2 shows a reversal diagram of a set of large rollers with respect to a set of small rollers at an angle φ; figure 3 and figure 4 presents a histogram constructed by the values of the gaps in the sets of rollers with the structure and without structure (serial technology), respectively; figure 5 shows the locking links of the diametric and radial dimensional chains of sets of rollers, where

and

- diametrical clearance in the large and small roller track;

and

- annular clearance in the roller sets of the large and small roller tracks.

The essence of the invention lies in the fact that the set of rollers on the large and small treadmills is assembled with minimum values of the gaps and the difference between these values should also be minimal. The set of rollers includes rollers from different selective groups with a certain structural sequence D _sr D _max D _min / d _max d _sr d _min . Then the set of rollers of the large roller track is deployed relative to the set of rollers of the small roller track at the calculated angle φ.

Analysis of the histograms (Figure 3 and Figure 4) allows us to establish the following property of assembly sets: the distribution of random gaps in sets with an ordered structure is more subject to the law of normal distribution than the distribution of random gaps in sets lacking an ordered structure. This property is taken into account in modeling the assembly process when choosing the tabulated quantile parameter of the normal distribution U _α .

The distribution series of the random gap in the roller sets, taking into account the structure, was checked using the Kolmagorov agreement criterion. So, we have for two series of distribution, respectively: 1-K (λ) = 0.922 and 1-K (λ) = 0.949. Based on the foregoing, we can conclude that the normal distribution can be considered consistent with the observed series of distribution.

The structural sequence determines the conditions of contact interaction of the cone teeth with rollers and rollers with each other. Between themselves, the rollers should interact in such a way as to reduce or eliminate the skewness of the axes of the cone and paws in the support, which allows you to evenly load the rollers in the support along the large and small roller tracks.

Conducted bench tests on the proposed method of assembly showed a positive result. A bit assembled using a new assembly method showed a 20% increase in life and a half-wear of the rollers compared to a bit assembled using serial technology.

Information sources

1. Friction, Wear, and Lubrication: A Guide. In 2 kn. / Ed. I.V. Kragelsky, V.V. Alisina. - M.: Mechanical Engineering, 1978. 400 p. (p. 122).

2. A.S. 2184203, Russia. Assembly method of roller cone bit. Morozov L.V., Remnev V.V., Pavlov M.Yu. Publ. in B.I. No. 18, 2000.

Claims (1)

A method of assembling a drill cone bit, which consists in pre-collecting sections, each of which consists of a roller cutter, a set of large and small rollers mounted respectively on a large and small treadmill of a paw axle, characterized in that the set of rollers for a large and small tread the tracks are assembled with the minimum calculated values of the annular clearances Xa, the difference between which should also be minimal, the rollers for the large and small treadmills are completed from different selective groups with optimal noy m assemblage structure which is determined by a substitution group of rollers mounted in a specific interleaving sequence _{D sr D max D min / d} max d sr d min, is performed turn sets of large rolls with respect to the set small at the calculated angle φ, the reference point for reversal is a label, applied on the base of the paw pin where D _max is the diameter of a large roller taken from the first selective group, mm; D _sr is the diameter of a large roller taken from the second selective group, mm; D _min - the diameter of a large roller taken from the third selective group, mm; d _max - the diameter of the small roller taken from the first selective group, mm; d _sr is the diameter of a small roller taken from the second selective group, mm; d _min - the diameter of the small roller taken from the third selective group, mm

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