RU2510449C1 - Manufacturing method of attachment of cutters to housing of drill crowns - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: essence of the invention consists in manufacture of a slotted joint by enclosing a shank of cutters with enveloping and inner rings. Inner rings are installed into opposite cavities on the crown housing by their being squeezed into radial slots of the crown housing. With that, material is extruded from under the end face of puncheons with forcing of the shank of cutters by the extruded mass down to the trailing wall of the radial slot. As a result, the cutter shank turns out to be rigidly fixed in the crown housing, thus forming press fit.

EFFECT: reduction of stresses in drilling cutters of annular crowns; improving sinking on a drill crown or load on the crown so that it can drill harder rocks.

4 cl, 6 dwg

Description

The invention relates to the engineering and mining industries, in particular to slotted joints with interference fit, and can be used for fastening plate cutters to the body of drill bits.

A known method of connecting carbide cutters to the body of the drill bits by soldering at a temperature of 950-970 ° C [1]. The advantage of connecting the cutters by soldering is the ability to attach the cutters to the body of the annular crown with a minimum width. At the same time, in self-sharpening crowns, incisors can be used almost 100%. However, a significant drawback of the method of soldering is the heating of carbide cutters and the steel body of the crown, the coefficient of thermal expansion of which differs almost twice. As a result of this, thermal stresses in the soldering zone cause premature failure of the drill bit cutters.

A known method of connecting carbide inserts with a roller cone and hammer drill bits by pressing into cylindrical nests [2]. Due to the mechanical fastening of these inserts, there are no thermal stresses in the inserts. Mechanical stresses in carbide inserts from being pressed into steel bit bodies are insignificant, due to the high elastic modulus of the hard alloy compared to steel. However, a significant drawback of the press joint method in rock cutting tools is that it is acceptable only for cylindrical inserts operating under axial pressure or impact. In conditions of significant tangential cutting forces and a narrow annular face, the press joint is of little use due to the impossibility of ensuring reliable operation of the joint.

The closest in technical essence and the achieved effect is the method of joining two sheets by cold forming and a device for its implementation [3]. The essence of the joining method is that two sheets are joined by cutting one of the sheets and forcing the material of the other into cuts of the first with extrusion of the material behind the cuts with the formation of edges. A positive feature of this method of connection is the ability to give the necessary shape (edges) to the extruded material for connecting parts, thereby achieving a reliable connection without auxiliary elements and operations. Compared to spot welding, there is no thermal effect causing warping of the sheets. The disadvantage is a narrow scope, limited to thin sheets, which makes it impossible to use it in many areas of technology, for example, in the attachment of cutters in drill bits. However, a more thorough analysis of the positive qualities of this method allows you to accept it as a prototype of the proposed new method of connecting cutters to the drill bit.

Thus, the task can be set to significantly reduce internal stresses in the drill bits of the annular crowns by applying some operations of the method of joining two sheets. When solving this problem, a certain technical result is achieved, expressed in increasing the penetration of the drill bit or the load on the crown with the aim of drilling stronger rocks.

The problem is solved by first providing the drill bit with the female and inner rings, installing them in the counter recesses of the crown body, and lamellar cutters installed right next to the running side of the radial flushing groove, turning the shank of the cutters between the female and inner rings, then using the outer and inner rings the punches are crushed to the middle of the width of the radial groove of the crown body of the female and the inner ring to mutual contact and squeezed the material of the female and the inside rennego ring from the end of the punch to force contact with the shank cutter, the shank is pressed against the upwind side of the radial slot and connected depressions formed in a single cavity with external and internal flushing channels.

Further possible embodiments follow from dependent claims 2-4.

In accordance with claim 2 of the invention, the punches are brought into periodic shock contact.

In accordance with paragraph 3 of the invention, to simplify installation, the inner diameter of the female ring is taken equal to or greater than the outer diameter of the crown, and the height of the female and inner rings and the depth of the recesses on the body of the crown are taken equal and calculated by the formula

, где $$t=\frac{nh}{2(\pi +n)}$$

where

n is the number of grooves;

h is the width of the radial groove.

Further, according to the invention, to facilitate the installation of the inner ring before assembly, the inner diameter and radial grooves of the body of the annular drill bit are pre-deformed.

Squeezing the female and inner rings into radial grooves causes an interference fit on the outer and inner sides of the cutter shank, and squeezing the material of the female and inner rings leads to pressing the cutter shank against the wall of the groove of the crown body. Thus, the proposed method of manufacturing the connection of the cutters to the crown ensures their reliable fastening to the body of the crown.

The proposed method of manufacturing a groove joint, despite the multi-operation, is technologically advanced and has high accuracy. High-amplitude cyclic thermal and mechanical action on the cutter in the attachment points during drilling does not cause its destruction due to internal stresses, since soldering is excluded. The manufacture of this compound by forcing the female and inner rings into the radial grooves of the crown body not only fixes the cutters, but also restores the message between the internal and external washing channels. Thus, the proposed method of manufacturing the connection allows you to use it for fastening the cutters in the drill bits and in some cases to refuse soldering, causing internal stresses in the cutters and their premature failure. In view of the foregoing, we believe that our proposal has novelty and inventive step.

The proposed method of manufacturing the connection of the cutters to the crown has the following advantages compared with the known:

- compared with soldering, the fastening of the cutters is carried out without inducing internal thermal stresses, which leads to an increase in the resistance of the cutters during drilling;

- the scope of the grooved connection has been expanded, namely, it can be used in fastening cutters to the body of the drill ring core;

- reliably solves the problem of fastening the cutters to the annular drill bit covering the inner and inner rings with the formation of the washing channel.

The essence of the invention is illustrated by the example of an annular drill bit in figure 1 ... 6. Figure 1 shows a General view of the groove connection of the cutters to the body of the drill bit made by the proposed method; figure 2 is a section of figure 1 along aa; figure 3 is a fragment of the connection in the context; figure 4 is a diagram of calculating the height of the enclosing ring, providing the ability to assemble without cutting it; figure 5 - inner ring prepared for assembly; Fig.6 is a diagram of the forcing and extruding material of the covering and inner rings from under the end face of the punches.

The drill bit contains connected parts of the crown body 1 and lamellar cutters 2 with a shank 3, auxiliary parts covering the ring 4 and the inner ring 5 (figures 1 and 2). The depressions 6 formed by the female and inner rings are in communication with the flushing channels 7 and the radial grooves 8 (FIGS. 1, 2 and 3). The shank of the incisors is processed under the "dovetail" or may have rectangular grooves on the sides. To place the female and the inner ring on the crown body, counter recesses (rectangular or trapezoidal grooves) are made according to its outer and inner diameter, the contours of which coincide with the contour of the cutter shank. To limit the movement of plate incisors in the longitudinal direction, the shank contacts the upper and lower shoulders of its grooves with the female and inner rings, while the end face of the shank of the cutters interacts with the bottom of the radial groove of the crown body.

The proposed method is carried out in the following way.

. Тогда перемещаемый объем должен разместиться по двум сторонам паза (фиг.4, заштрихованный участок), длина которых выразится формулой через параметры паза $$2(\frac{h}{2}-t)$$

. При этом на каждый паз приходится перемещаемый деформированием объем, соответствующий длине дуги, равной $$\frac{2\pi t}{n}$$

, где n - число пазов. Приравняв полученные выражения, получим высоту кольца или глубину выемки:The shank of the incisors is processed under the "dovetail" or produce rectangular grooves on the sides. On the body of the crown, counter cavities are made so that their contours coincide with the contour of the shank of the cutters, and the female and inner rings are also made with the possibility of their installation in these cavities. For ease of assembly, the female ring is made with an inner diameter equal to or slightly larger than the outer diameter of the crown R, then the length of its perimeter will be Δℓ longer than necessary for installation in an annular recess with a depth t equal to the height of the female ring (Fig. 4). Then Δℓ, as the difference in the circumference (2π (R + t) -2πR) is 2πt. Therefore, in order to realize this fastening without cutting the female ring, its volume corresponding to the length of the arc Δℓ must be moved into the corresponding radial groove 8 of the crown body by half its width $$\frac{h}{}$$$$\frac{}{2}$$

. Then the moved volume should be placed on two sides of the groove (Fig. 4, the shaded section), the length of which is expressed by the formula through the parameters of the groove $$2(\frac{h}{2}-t)$$

. At the same time, for each groove there is a volume displaced by deformation corresponding to the arc length $$\frac{2\pi t}{n}$$

where n is the number of grooves. Equating the obtained expressions, we obtain the height of the ring or the depth of the notch:

$$t=\frac{nh}{2(\pi +n)}$$

For the width of the end face of the crown h = 9 mm and the number of grooves n = 3, we obtain the height of the ring or the depth of the annular groove:

$$t=\frac{3\times 9}{2(3.14+3)}=2.2mm$$

In the manufacture of the inner ring so that it extends into the inside of the crown body, the deformation limit of the material of the ring can be exceeded by pressing it with a punch into the radial groove of the crown body. Therefore, the ring is made with a large diameter, based on the possibility of deformation without breaking. To do this, the inner ring is pre-deformed according to the inner diameter and radial grooves of the crown and installed in the inner recess of the crown body.

After installing the female and the inner rings in the annular recesses of the crown housing, the cutters are inserted between them by the shank and pressed against the incident side of the radial groove. In this case, the cutters can only move in the circumferential direction against the rotation of the crown, i.e. towards the radial groove of the crown body. Then, the inner and inner rings are pressed through the outer and inner punches to the middle of the radial groove of the crown body until they interconnect. For the final rigid fixation of the incisors, the material is squeezed out from under the end of the punches to force contact with the end of the incisors with their pressing against the incident side of the radial groove, forming a press fit. In this case, the extrusion is carried out by a 5-10-fold increase in pressure or by the application of shock loads to the punches.

Information sources

1. Drilling exploratory wells. Textbook for universities [Text] / N.V. Soloviev, V.V. Krivosheev, D.N. Bashkatov and others; Under the total. Ed. N.V. Solovyov. - M .: Higher. school, 2007 .-- 904 s .; silt.

2. Krylov, K.A. Improving the durability and efficiency of drill bits [Text] / K.A. Krylov, O.A. Streltsova. - Moscow: Nedra, 1983. - 208 p.

3. A.S. 1286099 USSR, B21D 39/03. The method of connecting two sheets and a device for its implementation [Text] / G.Yu. Ekold, X. Maass. (THE USSR). - No. 3868330 / 25-27; declared 03/21/85; publ. 04/30/1989, Bull. No. 16. - 6 p.: Ill.

Claims (4)

1. A method of manufacturing a connection of cutters to the body of drill bits by cold forming, in which operations are performed to form cavities and extrude material from under the end of the punch, characterized in that they first provide the crown with female and inner rings, install them in counter recesses of the crown body, and lamellar incisors are installed close to the running side of the radial groove, leading the shank of the incisors between the female and the inner rings, then using the outer and inner punches they press the female and inner rings into the radial grooves of the crown body to mutual contact and squeeze the material of the female and inner rings from under the end of the punches to force contact with the shank of the cutters, while the shank is pressed by the extruded mass to the running side of the radial groove, and the resulting cavities are connected into one cavity with external and internal flushing channels. 2. The method according to claim 1, characterized in that the punches are brought into periodic shock contact. 3. The method according to claim 1, characterized in that to simplify the installation, the inner diameter of the enclosing ring is taken equal to or slightly larger than the outer diameter of the crown, and the height of the enclosing and inner rings and the depth of the recesses on the crown body are taken equal and calculated by the formula:
$$t=\frac{nh}{2(\pi +n)}$$

,
where n is the number of radial grooves;
h is the width of the radial groove. 4. The method according to claim 1, characterized in that in order to facilitate installation, the inner ring is pre-deformed before assembly by the inner diameter and radial grooves of the drill bit body.

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