WO2008077278A1 - A lengthened sealing and bearing assembly of a roller bit - Google Patents

Abstract

A lengthened sealing and bearing assembly of a roller bit for drilling oil wells includes a body structure (2) and a cutter member (1) rotatably mounted on a cantilever spindle of the body structure (1). A circular groove (3) is formed on the end surface (13) of the cutter member for receiving a seal assembly. A lengthened bearing portion (12) of the cutter member is provided, and then the corresponding part of the body structure has an annular rim (11) around the outer periphery of the spindle's root. Using this lengthened sealing and bearing assembly, not only enough sealing space is obtained, but also enough load bearing contacting lengthis obtained to reduce effectively high load stress on the end surface of the bearing.

Description

 Extended sealed bearing for roller cone bit

Technical field

 The present invention relates to bearings and seals for roller cone bits for drilling on the earth's crust, and more particularly to an elongated seal bearing for a roller cone bit.

Background technique

 A roller cone bit has been widely used as a tool for drilling on the earth's crust. The upper end portion of a typical roller cone bit is coupled to a drill string, and the lower end portion includes a plurality of arms (typically three) each having a rotating shaft extending radially inwardly and downwardly to form a cantilevered shaft. A cone wheel is mounted on each cantilever shaft, and a set of bearings is mounted between the cone and the cantilever shaft to support its rotation. The bearing structure is divided into an open type bearing structure and a sealed type bearing knot. According to the structure of the radial bearing, the sealed bearing structure is further divided into a sealed sliding bearing structure and a sealed rolling bearing structure.

 The roller-type drill bit of the open-type bearing structure adopts a sealless radial roller bearing structure, and has the advantages that: the omitted sealing space can be used to lengthen the length of the roller bearing, thereby improving the bearing capacity of the roller bit. The disadvantage is the lack of lubrication, the bearing is prone to wear; the cuttings in the well are also easy to invade the bearing cavity, which leads to early wear of the bearing. A roller bit with a sealed bearing structure has a relatively good lubrication performance. However, once the seal component fails, the drilling debris enters the support surface through its gap, which will damage the bearing and cause early failure of the drill bit. So much research has focused on strengthening the sealing structure. U.S. Patent No. 6,695,079 discloses the use of a double seal structure to increase the operational life of the seal. However, the reinforced seat structure occupies a relatively large space, thereby shortening the support length of the large bearing and reducing the bearing capacity of the bearing. Therefore, it is necessary to balance the design of bearing life and sealing life, but the early failure of bearings or seals of such roller cone bits is still the main reason for its low life.

Summary of the invention The object of the present invention is to design an elongated sealed bearing structure for a roller cone bit to solve the technical problem of low life of the sealed bearing described above, and is suitable for a high load working environment.

 The technical solution of the invention is as follows: The invention adopts an elongated sealed bearing structure, which can obtain sufficient sealing space and obtain a sufficiently long bearing load contact line length, and effectively reduce the high contact stress of the singular distribution of the bearing end.

 An elongated sealed bearing for a roller cone bit, comprising a toothed sleeve (2) and a cone (1) mounted on the cantilever shaft of the tooth (2), characterized in that the cone end face (13) is provided with a cone End face circumferential groove (3), built-in sealing structure; set the cone large bearing extension (12); corresponding to the cone (1) of the tooth (2) has a palm-shaped raised ring at the periphery of the cantilever shaft root (11).

 The bearing structure of the sealed roller bit is mainly composed of a cantilever arm on the tooth (2) and three sliding bearings formed by the inner hole of the cone (1), including a large bearing, a small bearing and a thrust bearing. Among them, large bearings and small bearings mainly bear radial loads; thrust bearings mainly bear axial loads. The locking ball (6) is used to prevent the cone from falling off the pin journal when the bit is in operation. The invention is characterized in that the large bearing adopts an elongated sealed bearing structure, and a circumferential groove (3) of the end face of the cone is arranged on the end face (13) of the cone, and a sealing structure is built therein, so that the load contact between the cone and the cantilever axis of the tooth is achieved. The wire (14) extends into the inner diameter of the sealing structure to form a large bearing extension (12) of the cone, and the load contact line (14) between the extended cone and the cantilever shaft can effectively increase the bearing of the large bearing. Capacities; corresponding to the structure of the cone, the palm (2) has a palm-shaped raised ring (11) at the periphery of the root of the cantilever shaft for forming a sealing support with the sealing member. The labyrinth seal (7) and the rubber seal (8) act primarily to seal against external debris from entering the bearing while preventing lubricant loss in the bearing. The outer seal retaining ring (9) and the inner seal retaining ring (10) are used to secure the sealing member.

 The main advantages of the invention are:

1. The extended bearing structure can effectively reduce the contact stress on the large bearing in the sealed roller bit. It is not the high contact stress of the singular distribution at the end of the bearing.

 2. The diameter of the extended large bearing is relatively reduced. Under the same cone speed, the linear speed of the bearing rotation can be reduced.

 3. At the end of the cone, sufficient sealing space can be given for the cone bit seal under severe working conditions, and a multi-stage sealing structure can be adopted.

 4. The sealing method combined with the labyrinth seal and the rubber seal can prevent the external cuttings from intruding into the bearing and prevent the loss of lubricant in the bearing.

DRAWINGS

 Figure 1 shows an extended bearing structure in which the cone is in direct sliding contact with the cantilever shaft of the palm.

 Fig. 2 is a partial enlarged structure of the circumferential groove of the end face of the roller and the extension of the large bearing of the cone.

 Figure 3 shows the structure of a sliding extended bearing with a large sliding bushing.

 Figure 4 shows the structure of a rolling extended bearing with rollers.

 Wherein, the cone 1, the palm 2, the circumferential end groove 3 of the cone end face, the small sliding bearing sleeve 4, the circular thrust washer 5, the locking steel ball 6, the labyrinth type sealing member 7, the rubber sealing member 8, the outer seal The retaining ring 9, the inner sealing ring 10, the palm protruding ring 11, the cone large bearing extension 12, the cone end face 13, the load contact line 14 between the cone and the cantilever axis, the cone and the large sliding Load contact line 15 between sleeves, load contact line 16 between the cantilever shaft and large sliding sleeve, large sliding sleeve 17, roller fe 18, load contact line between cone and roller 19, cantilever The length of the load contact line 20 between the shaft and the roller, the length of the L1-cone large bearing extension, and the length of the L2-cone for the sealed space portion (the length of the end of the cone to the bottom of the circumferential groove).

detailed description

Within the scope of the invention, the bearing and sealing structure in each cone on the roller bit is a basic phase In the same way, only one of the inner structures of the cone is described in detail in conjunction with the drawings. According to the structure of the large bearing, the roller bit with the elongated bearing structure is divided into three types: an elongated bearing structure in which the cone is directly slidingly contacted with the cantilever shaft of the tooth, and the sliding of the large sliding sleeve (17) is lengthened. Type bearing structure and rolling extended bearing structure with roller (18).

For the elongated bearing structure in which the cone and the cantilever shaft are in direct sliding contact, the cantilever shaft on the palm (2) and the inner hole of the cone (1) form three sliding bearings, large sliding bearing and small sliding bearing. And a thrust bearing; wherein, the large bearing formed by the direct sliding contact between the cone and the cantilever shaft of the tooth and the small bearing provided with the small sliding bearing sleeve (4) are mainly subjected to radial load; and the circular thrust for the thrust bearing The washer (5) is mainly subjected to axial load; the locking steel ball (6) is used to prevent the cone from falling off the cantilever shaft of the tooth when the drill bit is working. ¹

 The large bearing adopts the extended seal bearing structure, and the circumferential end groove (3) of the cone end face is arranged on the end face (13) of the cone, and the sealing structure is built in, so that the load contact line (14) between the cone and the cantilever axis of the tooth is Figure 1) extends into the inner diameter of the sealing structure, forming a large bearing extension (12) of the cone, and the extended load contact line can effectively increase the bearing capacity of the large bearing; the working length of the large bearing is larger than that of the previous seal. The length is lengthened by L1 (the length of the extension of the large bearing of the cone), and the length L1 of the lengthened portion of the bearing can be less than, equal to or even greater than the length L2 of the portion of the cone for the sealed space; the section of the extended portion of the cone (12) The shape may be rectangular or trapezoidal; the tapered bearing large bearing extension (12) shown in the figure has a slope, which is narrower near the end face of the cone and wider than the end face.

Corresponding to the structure of the cone, the palm (2) has a palm-shaped convex ring (11) at the periphery of the root of the cantilever shaft for forming a sealing support with the sealing member, the palm-shaped convex ring (11) ) can be directly machined on the palm part, or it can be combined by inlaying method; it matches the shape adopted by the large bearing extension part (12) of the cone, and the palm-shaped raised ring (11) The section can be rectangular The shape may also be a corresponding trapezoid; the trapezoidal palm-shaped raised ring (11) shown in the figure has a corresponding slope, which is wider near the palm portion and narrower at the outer end surface.

 The surface reinforcement process can be used to strengthen the inner hole of the cone (1), the extended portion of the large roller bearing (12), the cantilever shaft on the palm (2), and the sealing support generated by the crown ring (11). surface.

 In a sufficient sealed space, multi-stage sealing can be used. Here is a two-stage sealing structure; the outer sealing structure consists of a labyrinth seal (7), an outer seal ring (9) and a palm protrusion. The ring (11) forms a labyrinth seal, the main function is to prevent or slow the invasion of external cuttings; the inner seal structure consists of a rubber sealing member (8), an inner sealing ring (10) and a raised palm ring ( 11) The rubber seal is formed to prevent the loss of lubricant in the bearing and the intrusion of external cuttings.

 The outer seal ring (9) and the inner seal ring (10) can be fixed together with the cone by means of static fit or threaded fit; labyrinth seal (7), outer seal ring (9) The inner sealing ring (10) is made of high strength and high wear resistance.

 Since the elongated bearing structure is used, the relative displacement of the cone at the sealed space corresponding to the palm is small, so that a labyrinth seal structure can be employed.

 The extended sealed bearing structure can also be provided with a large sliding sleeve (17), as shown in Fig. 3; this can increase the load contact line (15) between the cone (1) and the large sliding sleeve (17) and the teeth The length of the load contact line (16) between the palm (2) cantilever shaft and the large sliding bushing (17) also has the advantages of the above described elongated bearing structure.

 Figure 4 shows the structure of an elongated rolling bearing with rollers (18). The bearing structure is provided with the addition of a long roller (18) instead of the large sliding bushing (17) of Fig. 3, which also increases the load contact line (19) between the cone (1) and the roller (18) and The length of the load contact line (20) between the cantilever shaft (2) and the roller (18) has the same advantages as above.

Claims

Rights request  1. An elongated sealed bearing for a roller cone bit, comprising a tooth (2) and a set of teeth (2) A cone (1) on the cantilever shaft, characterized in that the end face of the cone (13) is provided with a circumferential groove of the end face of the cone (3), built-in sealing structure; set the large bearing extension of the cone (12) corresponding to the tooth of the cone (1) (2) has a palm-shaped raised ring (11) at the periphery of the root of the cantilever.  2. An elongated seal bearing for a roller cone bit according to claim 1, characterized in that a two-stage seal is used, and the outer seal structure is a labyrinth seal member (7) and an outer seal ring (9). And the palm raised ring (11) constitutes a labyrinth seal; the inner seal structure is composed of a rubber seal member (8), an inner seal ring (10) and a palm raised ring (11) to form a rubber seal.  3. An elongated sealed bearing for a roller cone bit according to claim 1 or 2, characterized in that the large bearing can be a sliding bearing or a roller (18) provided with a large sliding bushing (17) Rolling bearings.