RU2433243C2 - Box-type rolling drilling bit - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: box-type rolling drilling bit comprises a centre box with side hollows each of which has guide pins at the bottom for mounting and fastening of support brackets with movable rolling cutters mounted on journals. Each support bracket is supplied with a threaded through holes formed between a pair of holes for guide pins in a plane passing through their axes, and an expander element in the form of a threaded cap rod screwed in the threaded through holes. One end of the threaded rod rests against the box when screwed in the threaded through hole, and expands a section until mounted in a zero-tolerance position with respect to a bit diameter before tacking and box welding. Similarly, the two other sections are expanded when inverse cones of the rolling cutters rest against an internal surface of a rigid diametral ring gauge coaxial to the box.

EFFECT: higher accuracy, reliability and period of service of the box-type bits.

6 dwg

Description

Known drill bits of the sectional type, the body of which is formed during assembly and connection by welding of individual sections with subsequent threading for attachment to the drill string. With an increase in the diameter of such bits, the dimensions and mass of the component parts, especially the paws, greatly increase. In the manufacture of sectional bits from small to medium diameters (from 76 to 320 mm), the paw blanks can be obtained by volumetric stamping with a force on stamping presses of up to several thousand tons.

For the manufacture of sectional bits of increased diameter (up to 660 mm or more), it is impossible to produce paw blanks by the method of die forging, even with a multi-ton force. Such blanks are forced to perform an even more complex method of volume forging on stamping hammers with a mass of falling parts of up to 10 or more tons.

During the machining of large-sized workpieces, laboriousness sharply increases, expensive large-sized equipment, lifting devices and equipment are required. Therefore, in the manufacture of oversized drill bits, machine builders give preference to hull-type designs, since individually the dimensions and mass of the hull and feet are significantly smaller than those of paws of the same size sectional type.

Known cone drill bit of increased diameter [1], taken as an analogue. Such a chisel consists of a cast body and sections, including paws, on the trunnions of which the cones with rock-cutting teeth on the surface are movably fixed. The advantages of such bits are the simplicity of construction and the relatively easy manufacture of individual bodies and legs.

The disadvantage of such bits is the low accuracy of the output parameters due to the presence of a massive cast body with large tolerances on casting.

Based on such a housing before welding sections leads to the formation of large radial and end beats cones. Significantly lower are the strength properties of cast guides protruding above the body. Sometimes cracks formed in the molded guides, and they broke during drilling, and with them entire sections remained in the face. For these reasons, preference was given to leading chisel firms with sectional chisels of increased diameter that did not have a separate body. However, drillers need larger and larger bits - up to 660 mm or more in diameter. Therefore, the idea of using body bits was not forgotten.

Known drilling cone bit of the hull type with reduced dimensions of the casing and sections, adopted for the second analogue [2]. Its special advantages include the small dimensions of the paws, which reduce the complexity of their technology. When assembling the bit, each of the paws is installed inside one of the grooves in the body and secured there using stepped threaded pins with a set of clamping nuts and locknuts.

Each stepped pin has two threads - one for turning into a hole on the body, the other for clamping the legs. Moreover, on the flat surface of each longitudinal groove on the body, made parallel to its axis, there are three threaded holes with axes in a plane passing through the axis of the body. Larger threaded pins are screwed into the threaded holes until the pin rests on the pin inside the recess on the housing around the axis of the holes.

A paw with through holes for three pins is mounted and based on them. Then, nuts are screwed over a reduced-sized thread protruding above the surface of the housing to tightly press the section against the flat surface of the groove on the housing. To prevent the flap of these nuts from being folded, locknuts are wound next to the pins.

The second analogue has three drawbacks. The first is the insufficient reliability of the pin fastening when working on the bottom, when loads are tens of tons and drilling occurs with continuous pulsation of the column, the holding sections of the thread can simply break.

Another disadvantage is that the case itself is composite. The threaded cover for attaching the bit to the column is attached to the body with threaded bolts whose axes are parallel to the axis of the body. Such fastening during vibration in drilling conditions is unreliable.

The third disadvantage of the second analogue is the difficulty of regulation when assembling the position of the sections with cones relative to the axis of the thread and the body. When processing flat pads in the case for installing paws, threaded holes for pins, processing flat pads on paws for contacting grooves on the body, tolerances are set for each operation.

The addition of tolerances leads to a significant difference in the position of the inverse cones of the cones relative to the thread of the bit, and hence the radial runout of the sections. In the case when the diameter of the bit after assembly is greater than the allowable one according to the drawing, the bit must be disassembled and other, less complete sections selected. And in the case when this diameter is less than the permissible, the bit also needs to be disassembled and put gaskets under the sections until the required bit diameter is reached.

Known for other roller cone drill bits of the hull type with an improved flushing system [3], adopted as a prototype. As in the second analogue, several symmetrically located recesses with a flat inner wall parallel to the central axis and symmetrical side walls are made on the body with a thread connecting to the pipe string. Sections — paws with cones movably fixed on their pins and equipped with rock-cutting teeth — are installed in these depressions. Instead of stepped fastening pins with two thread sizes on the steps presented in the second analogue, in the prototype sections are assembled on the body using a pair of smooth cylindrical guide pins installed at one end into the hole on the bottom of the inner wall of the recess on the body. The axes of these holes are located in a plane passing through the axis of the housing.

The other ends of the smooth guide pins protrude above the bottom of the groove in the housing. On the flat surface of the paw there are two mating holes facing the pins on the flat surface of the recess. When assembling, smooth pins are a necessary base for assembling paws with cones on the body.

As the drill pipe or hydraulic motor shaft rotates, a significant axial load acts on the body of the bit, which must be transmitted to the cones through the ends of the assembled paws. The area of interaction between the body and paws is provided by the contacts of the ends of the recesses and the ends of the set paws, as well as welding seams made along the outer contours of the paws bordering the walls of the recesses in the body.

The disadvantage of the prototype is, as for both analogues, the difficulty of assembling the sections in the bit, with obtaining the exact size of the diameter of the bit with a minimum tolerance and minimum radial runout.

The technical result of the present invention is to improve the accuracy, reliability and durability of case-type bits. This result is achieved by the fact that in a chisel including a body with connecting thread, side recesses with a flat bottom parallel to the axis, inserted into the holes on the bottom by pairs of smooth guide pins, legs with cones movably fixed on their trunnions equipped with rock cutting teeth, the internal cavity and a system of channels for supplying flushing fluid to the bottom; in each paw, sliding elements are made, which make it possible to force the sections along the guide pins to push apart to the zero position - the emphasis of the inverse cones of the cones on the inner surface of the rigid, coaxial with the axis of the body of the caliber ring.

The said expanding elements in each leg are made in the form of a through hole, on the walls of which there is a thread. Preferably, the openings of the sliding elements are aligned with the axes of the guide pins of the smooth pins and in the middle of the distance between them. Spreading elements in the form of a threaded rod with a turnkey head longer than the depth of the through holes. A thread is a mating thread in the through holes, as well as a hex or other shape head for turning in through holes.

When the bolts are inverted after contact with a flat bottom in the recesses of the housing of the section, they begin to move apart to the stop on the surface of the caliber ring.

The list of drawings.

Figure 1 shows the body bit prototype with one extended section. Figure 2 presents a bottom view of the body of the prototype bit. Figure 3 shows a section of the proposed bit with an extended paw and cone. Figure 4 shows a bottom view of the body of the proposed bit. Figure 5 shows a section of the proposed bit with sections pressed to the body. Figure 6 shows a section of the proposed bit with sections spaced to contact with the caliber ring.

Figure 1 marked: 1 - the body of the bit; 2 - groove in the housing with contact guide pins 3; paw - 4 with mating holes 5 for pins 3 and contact plane 6; lubrication system 7 and channels for lubrication 8; cone 9 with a node for sealing 10 and bearings bearings 11, 12 and 13; rock cutting elements 14.

Figure 2 marked: 1 - the body of the bit 1 (bottom view); grooves 2; the surface of the bottom of the groove 15 and the side surfaces of the grooves 16, 17 for installing the legs; outlet openings for installing flushing nozzles 18.

Figure 3 marked: 19 - the housing of the proposed bit with side recesses on the housing 20; guide base pins 21; paw 22 shifted from the housing 19 with holes 23 corresponding to the pins 21; lubrication system 24 in the paw 22 with a feed channel 25; a through hole 26 with a thread 27; base flat end surface 28; shifted along the axis of the axle of the leg 22 of the cone 29 with a seal support 30; bearings 31, 32, 33; rock cutting teeth 34.

Figure 4 marked: 19 - the body of the bit (bottom view along arrow A); side recesses 20 for installing legs 22; guide base pins 21; base flat bottom 35 on the recesses 20; a central flushing hole 36 and side flushing channels 37 in the tides 38 of the housing 19; the walls of the side recesses 39 and 40.

In Fig. 5, the following are indicated: 19 — the body of the bit with its paws 22 pressed against it closely along the guide pins 21 until the planes 35 of the body 19 and the paw plane 28 come into contact. and o-ring 41. Pos. 42, the sliding elements are indicated, for example, in the form of a rod with a thread 43 and a turnkey head 44.

Figure 6 marked: 19 - the body of the bit with legs 20; extending elements 43 along the guide pins 21 until the inverse cones 45 of the cones 29 contact the inner surface of the mounting gauge of the ring 46. After that, the legs 20 are gripped and then welded to the body 19 along the entire common side and end perimeter of the contact with a welding seam, conventionally designated 47.

The installation of the sliding elements 43 of all three sections symmetrically to the axis of the housing 19 along the diameter of the caliber of the ring 46 before welding ensures the most accurate, without the diameter tolerance previously inevitable, uniform size for all assembled bits, with zero radial runout and without any compensation gaskets. This allows to increase the operational performance of the proposed bits in drilling and significantly simplify the technology of their manufacture, as evidenced by the manufacture and testing of samples.

Information sources

1. Reference manual "Tool for drilling wells, ed. I.K. Maslennikov and G.I. Matveev, Moscow, "Nedra", 1981

2. US patent No. 5199516, Е21В, 10/20 "Modular drill bit" from 04/06/1993

3. US patent No. 5641029, Е21В, 10/20 "Modular leg of a rotary cone bit" dated June 24, 1997.

Claims (1)

A cutter-type drill bit containing a central body with lateral recesses, at the bottom of each of which there are pairs of guide pins to base paws on them with movably fixed cones having rock cutting teeth, characterized in that the paws have threaded through holes located between the pair holes for the guide pins in the plane passing through their axis, and the sliding elements in the form of a threaded rod with a turnkey head in contact with the housing at one end and protrude above the paw, providing the position of the sections with zero tolerance with respect to the diameter of the bit before tacking and welding them with the body when the inverse cones of the cones stop on the inner surface of the rigid coaxial body of a dimensional diametric ring gauge.

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