IE48451B1

IE48451B1 - Roller drill bit

Info

Publication number: IE48451B1
Application number: IE1353/79A
Authority: IE
Original assignee: Sandvik Ab
Priority date: 1978-05-31
Filing date: 1979-08-08
Publication date: 1985-01-23
Also published as: NL7904233A; AU532730B2; PL121979B1; AU4760179A; FR2427460B1; PL214440A1; IE791353L; BR7903396A; SE7904516L; GB2022170A; IT7922644A0; GB2022170B; FR2427460A1; IT1166825B; MX147386A

Abstract

The invention provides a roller drill bit having a body (10), a pin (11) extending from the body and a cutter (12) mounted on the pin for rotation about the pin, the cutter being mounted by a rolling bearing (13) having rolling members (16) disposed in radially inner and outer opposed raceway grooves (19, 20) in the pin and cutter respectively. The pin has an aperture (25) extending parallel to the axis of the pin from outside the drill bit body along to and opening into the radially inner raceway groove. The aperture is dimensioned to allow the rolling members of the bearing to pass along the aperture and into the raceway grooves. A plug (26) is fixed in the aperture to locate the rolling members in the raceway grooves.

Description

This invention concerns a roller drill bit.

The invention provides a roller bit having a body, a pin extending from the body and a cutter mounted on the pin for rotation about the pin, the cutter being mounted by a rolling bearing having rolling members disposed in radially inner and outer opposed raceway grooves in the pin and cutter respectively, the pin having an aperture extending substantially parallel to the axis of the pin from outside the drill bit body along to and opening into the radially inner raceway groove, the aperture being dimensioned to allow the rolling members of the bearing to pass along the aperture and into the raceway grooves, a plug being fixed in the aperture to locate the rolling members in the raceway grooves.

The cutter may have an annular portion on the side of the bearing nearest the bit body, which portion may form a sealing gap with the pin, and the distance radially of the pin axis between the radially inner surface of said portion and the wall of the aperture nearest the pin axis may be no less than the maximum diameter of any rolling member.

In use of the roller drill bit, load may be transmitted from the cutter radially in one direction to the pin, and the aperture may be located on the diametrically opposite side of the axis of the pin to which load is transmitted.

The plug may provide a surface for the rolling members which conforms closely to the inner raceway surface.

The plug may comprise a resiliently deformable material.

The said plug may have a bore and a further plug may be provided which further plug may have a projection extending as a force fit into the bore of the first said plug.

The cutter may be mounted by a plurality of rolling bearings, and a plurality of apertures in the pin may be provided, one opening into each bearing.

The cutter may be mounted by a plurality of rolling bearings, and a single aperture in the pin may open into each bearing.

A plurality of plugs may be provided in the single aperture, one locating the rolling members of one bearing and each plug may be interconnected to an adjacent plug to prevent rotation of the plug relative to another.

Embodiments of the invention will now be described by way of example, reference being made to the accompanying drawings, of which: Figure 1 is a longitudinal section through a cutter mounted on a pin of a roller drill bit; Figure 2 is a section on A-A of the bit shown in Figure 1; Figure 3 is a longitudinal section through a cutter mounted on a pin of another roller drill bit; Figure 4 is a part of a longitudinal section through a cutter mounted on a pin of a further roller drill bit; Figure 5 is a part of a longitudinal section through a cutter mounted in a pin of yet another roller drill bit; Figure 6 is a longitudinal section through a cutter mounted on a pin of yet a further roller drill bit; 84 5 1 Figure 7 is a section on B-B of the bit shown in Figure 6; and Figure 8 is a perspective view of the plug shown in Figures 6 and 7.

Referring to Figures 1 and 2, the roller drill bit has a body 10, a pin 11 extending from and integral with the bit botfy, and a generally conical cutter 12. The cutter 12 is mounted for rotation about the pin 11 by two radial rolling bearings 13 and 14, and an axial rolling bearing 15. The radial rolling bearings 13 and 14 have cylindrical rollers 16 and 17 respectively. The axial rolling bearing 15, which is located between the radial rolling bearings 13 and 14, has tapered rollers 18. The rollers 16 of bearing 13, which is nearest to the bit body 10, are disposed in radially inner and outer opposed raceway grooves 19 and 20 in the pin 11 and cutter 12 respectively. Groove 19 in pin 11 forms rims 21 and 22 which guide the rollers 16, and groove 20 in cutter 12 forms a rim 23 which also guides the rollers. from Cutter 12 is prevented from being pulled off/pin 11 by rims 21, 22 and 23 and rollers 16.

An annular seal 24 is located in a recess in rim 23, bears on an axially facing surface of the bit boc(y 10 and seals off the bearing chamber of the cutter 12. The rim 23 of the cutter 12 on the side of the bearing 13 closest to the bit body 10 forms a sealing gap with the outer surface of the pin 11.

The pin 11 has an aperture 25 extending parallel to the axis of the pin from outside the drill bit body 10 along to and opening into the groove 19 of the bearing 13. The aperture 25 is so dimensioned to allow the cylindrical rollers 16 of the bearing 13 to pass along the aperture and into the raceway grooves 19 and 20. A plug 26 is fixed in the aperture 25 to locate the rollers 16 and has a surface 27 which conforms closely to the surface of the inner raceway groove 19 so that there are no irregularities or holes.

A cylindrical locking pin 28 engages in recesses in both the bit body 10 and plug 26 so preventing the plug from turning in the aperture 25.

The diameter of the opening into the cutter 12 is that of the rim 23 which is positioned close to the outer surface of the pin 11. This allows the grooves 19 and 20 to he relatively deep so that rollers 16 are guided and securely retained between the rims 21, 22 and 23 which are integral with the pin 11 and cutter 12 respectively.

The distance 29, radially of the axis of the pin 11, and inside the aperture 25 between the radially inner surface of the rim 23 and the wall of the aperture nearest the pin axis, is no less than the diameter of the rollers 16, so that when the drill bit is being assembled, the rollers 16 can be pushed through aperture 25 inside the rim 23 and into the raceway 19 of the pin 11. From there they are brought out into raceway groove 20 of the cutter 12 and are distributed around the pin 11 by rotation of the cutter. After the rollers 16 have been introduced, the aperture 25 is closed by plug 26 and locking pin 28 is positioned. The plug 26 and pin 28 are fixed in position in the bit body 10 by welding at 30 at the entrance of the aperture 25.

Referring to Figure 3, the roller drill bit has in common with the embodiment of Figures 1 and 2, a bit body 40, a pin 41, a cutter 42, a radial cylindrical roller bearing 43 and an axial tapered roller 8 4 51 bearing 44. In this embodiment however there are two adjacent radial ball bearings 45 and 46, bearing 45 having the larger diameter balls being disposed nearer the bit body 40 to take the higher loads.

The balls of bearings 45 are disposed in radially inner and outer raceway grooves 47 and 48 in the pin 41 and cutter 42 respectively, and the balls of bearing 46 are disposed in radially inner and outer raceway grooves 49 and 50 in the pin 41 and cutter 42 respectively.

The cutter 42 is thus prevented from disengaement with pin 41.

A resiliently deformable seal 51 is secured by means of a sleeve 52 in the cutter 42 on the side of bearing 45 nearest the bit body 40. The seal 51 slides on axially facing surface 53 of the bit body 40 and radially outer surface 54 of the pin 41.

The pin 41 has a single aperture 55 extending parallel to the pin axis from outside the drill bit body 40 along to and opening into both the raceway grooves 47 and 49 in the pin of the bearings 45 and 46 respectively. When the cutter 42 is mounted on the pin 41 as shown, two plugs 56 and 57 are fixed in the aperture 55. Plug 57 locates the balls of bearing 46 and plug 56 locates the balls of bearing 45 in the raceway grooves. Plug 57 has a projection 58 extending into and engaging a recess 59 in plug 56 so that the plugs are interconnected and prevented from rotating relative to each other.

To assemble the roller drill bit and mount cutter 42 on pin 41, the tapered rollers of bearing 44 are fitted in position in the bearing chamber of cutter 42, and the cylindrical rollers of bearing 43 are fitted into a groove in pin 41. The cutter 42 is then pushed axially over the pin 41 until the tapered rollers of bearing 44 contact the pin 41. The balls of bearing 46 are then pushed through the aperture 55 and into raceway grooves 49 and 50. Plug 57 is then pushed into aperture 55 until it reaches and closes the opening of the aperture into the groove 49 so locating the balls of bearing 46 in the raceway grooves.

The balls of bearing 45 are then pushed through the aperture 55 and are just able to squeeze inside seal 51 and pass inside of rim 60 to enter into raceway grooves 47 and 48. Aperture 55 is then filled with the second plug 56 to close the opening of the aperture into raceway groove 47. Plug 56 is then welded at 61 to bit body 40.

In use of the roller drill bit of the embodiments of Figures 1 and 2 and Figure 3, load is transmitted from the cutter 12, 42 radially in one direction to the pin 11, 41. Aperture 25, 55 is located on the diametrically opposite side of the axis of the pin 11, 41 to which load is transmitted so that the load-carrying capability of the bearings 13 and 45, 46 is not impaired by the aperture 25, 55.

The embodiment shown in Figure 4 has in common with the embodiments of Figures 1 and 2 and Figure 3 a bit body 70, a pin 71, a generally conical cutter 72, a radial cylindrical roller bearing 73 and an axial taper roller bearing 74. There are also two adjacent radial cylindrical roller bearings 75 and 76. The rollers of bearing 75 are disposed on a radially inner raceway surface 77 on the pin 71 but not in a groove, and in a radially outer raceway groove 78 in the cutter 72. The rollers of bearing 76 are disposed in opposed radially inner and outer raceway grooves 79 and 80 in the pin 71 and cutter 72 respectively. A rim or flange 81 is formed between the two bearings 75 and 76 and integral with the cutter 72 so that the cutter 72 is prevented by means of bearing 76 from being pulled off the pin 71. , 48451 A resiliently deformable seal 82 of, for example, plastics is located by the sleeve 83 in a recess in a portion of the cutter 72 on the side of the bearing 75 nearest the bit body 70 to slide on radially and axially facing surfaces of the pin 71 and bit body 70 respectively.

A single aperture 84 extends parallel to the axis of the pin 71 from outside of the drill bit body along to and opens into both the raceways 77 and 79 of the bearings 75 and 76 respectively. The aperture 84 lies on the opposite side of the axis of the pin 71 to which load is transmitted in use of the drill bit, so that the load carrying capability of the bearings 75 and 76 is not impaired.

The assembly of the roller drill bit of this embodiment is done in a similar manner to that of the previously described embodiments. The cylindrical rollers of bearing 76 are passed through aperture 84 first and then into the raceway grooves 79 and 80. The radial distance 85 between the wall of the aperture 84 nearest the axis of the pin 71 and the radially inside surface of the rim 81 must be no less than the diameter of the rollers. By making the diameter of the rim 81 slightly greater, then the radial distance 85 is increased making the insertion of the rollers easier whilst still keeping the size of the aperture relatively small. After all the rollers of bearing 76 are in place, the opening of the aperture 84 into raceway groove 79 is closed by a short temporary plug (not shown) to prevent the rollers from dropping back into the aperture. Ihen the cylindrical rollers of bearing 75 are passed through aperture 84 and into raceway groove 78. The temporary plug is then removed and a single plug 86 is fixed into aperture 84 by welding at 87 to locate the rollers of bearings 75 and 76 in their raceway grooves.

The plug 86 can consist of a relatively inexpensive soft material, for example, by weldable carbon steel, because the aperture 84 is located on that side of the pin 71 where the bearings 75 and 76 are subject to relatively little radial loading. Besides the plug 86 providing surfaces conforming closely to the inner raceways 77 and 79, it also provides a surface conforming closely to the outer surface of the pin 71 adjacent to the bit body 70 so that there are no corners or edges to damage the seal 82.

Figure 5 shows a modification of the embodiment of Figure 4 in which integral rim 81 is replaced by a spacer ring 88 composed of two semi-circular parts and mounted in the radially outer groove 78 adjacent to the rollers of bearing 75. The cutter 72 is thus retained on pin 71 by means of rim 89 on the side of bearing 75 nearest to the bit body 70, by bearing 75, spacer ring 88 and bearing 76.

The embodiment shown in Figure 6, 7 and 8 is basically the same as the embodiment of Figures 1 and 2 and has a bit body 100, a pin 101, a cutter 102, radial cylindrical roller bearings 103 and 104 and an axial tapered rolling bearing 105. A slightly different seal 106 is used in place of ring seal 24. Aperture 107 is used for introducing the rollers of bearing 103 into opposed radially inner and outer raceway grooves 108 and 109. The basic difference is that instead of a single plug 26 there are an inner plug 110 and an outer plug 111.

Inner plug 110 consists of a resiliently deformable material, such as rubber or plastics, and has a bore 112. Outer plug 111 has a projection 113 which extends as a force fit into the bore 112.

After the cylindrical rollers of bearing 103 have been introduced into the raceway grooves 108 and 109, the resiliently deformable inner plug 110 is radially compressed to fit into aperture 107, which causes bore 112 to get smaller. The plug 110 is then pushed down aperture 107 until a projection 114 on the plug fits into the opening 115 of the aperture into the inner raceway groove 108 so that the opening is at least partly closed. Outer plug 111 is then pushed into the aperture 107 and the projection 113 forced into the bore 112 so enlarging plug 110 to firmly contact the walls of openings 115. This ensures a tight fit of the inner plug 110 in the aperture 107 and opening 115 so that there is no need for expensive close production tolerances between plug 110 and aperture 107. After the outer plug 111 is in position, it is fixed to the bit body 100 by welding at 116.

A roller drill bit according to the invention is not limited to the embodiments described with reference to and as shown in the accompanying drawings. Modifications are envisaged; for example, a single aperture may be used for introducing the rolling members of more than two radial rolling bearings, the aperture extending from outside of the drill bit body and along to and opening into each inner raceway. The aperture can also be used to introduce the rolling members of one or more axial rolling bearings.

The raceways described and shown are provided directly on the cutter and pin, but race rings may be used and which are fixed to the cutter or pin. Although the rolling bearings are shown as not having a cage the rolling members may be guided by conventional cages segments or spacers.

Instead of a single aperture for a plurality of rolling bearings, there may be one aperture for each bearing. However, the strength of the pin will be reduced by the increasing number of apertures.

A roller drill bit constructed according to the invention has the advantage that it is simple and cheap to product as there are only a few readily machined parts. Production and assembly is simplified with the pin being integral with the bit body. And there is the great advantage that the cutter is securely held on the pin by a radial rolling bearing having rolling members disposed in raceway grooves, the rims of which are integral with the pin and cutter, which rims therefore cannot work loose.

Claims

1. A roller drill bit having a body, a pin extending from the body and a cutter mounted on the pin for rotation about the pin, the cutter being mounted by a rolling bearing having rolling members 5 disposed in radially inner and outer opposed raceway grooves in the pin and cutter respectively, the pin having an aperture extending substantially parallel to the axis of the pin from outside the drill bit body along to and opening into the radially inner raceway groove, the aperture being dimensioned to allow the rolling members of the bearing to pass along 10 the aperture and into the raceway grooves, a plug being fixed in the aperture to locate the rolling members in the raceway grooves.

2. A roller drill bit as claimed in claim 1, wherein the cutter has an annular portion on the side of the bearing nearest the bit hotty, which portions forms a sealing gap with the pin, and the distance radially of 15 the pin axis between the radially inner surface of said portion and the wall of the aperture nearest the pin axis is no less than the maximum diameter of any rolling member.

3. A roller drill bit as claimed in claim 1 or 2, wherein, in use of the roller drill bit, load is transmitted from the cutter 20 radially in one direction to the pin, and the aperture is located on the diametrically opposite side of the axis of the pin to which load is transmitted.

4. A roller drill bit as claimed in any preceding claim, wherein the plug provides a surface for the rolling members which conforms 25 closely to the inner raceway surface.

5. A roller drill bit as claimed in any preceding claim, wherein the plug comprises a resiliently deformable material.

6. A roller drill bit as claimed in claim 5, wherein the said plug has a bore, and a further plug is provided which further plug has a projection extending as a force fit into the bore of the first said plug. 5

7. A roller drill bit as claimed in any preceding claims, wherein the cutter is mounted by a plurality of rolling bearings, a plurality of apertures in the pin being provided, one opening into each bearing.

8. A roller drill bit as claimed in any one of claims 1 to 6, wherein the cutter is mounted by a plurality of rolling bearings, and 10 a single aperture in the pin opens into each bearing.

9. A roller drill bit as claimed in claim 8, wherein a plurality of plugs are provided one locating the rolling members of one bearing, each plug being interconnected to an adjacent plug to prevent rotation of one plug relative to another. 15

10. A roller drill bit substantially as herein described with reference to and as shown in Figures 1 and 2, or with reference to and as shown in Figure 3, or with reference to and as shown in Figure 4, or with reference to and as shown in Figure 5, and with reference to and as shown in Figures 6, 7 and 8 of the accompanying drawings.