US3820613A

US3820613A - Roller reamer stabilizer

Info

Publication number: US3820613A
Application number: US00340250A
Authority: US
Inventors: K White
Original assignee: Western Rock Bit Co Ltd
Current assignee: Western Rock Bit Co Ltd
Priority date: 1972-12-29
Filing date: 1973-03-12
Publication date: 1974-06-28
Anticipated expiration: 1991-06-28
Also published as: CA1016534A

Abstract

A roller reamer stabilizer the bearings of which are lubricated by air bleed from the centre core of the drill string. The roller cutters are mounted in recesses in the body such that the roller cutters are free to rotate about their bearing pins in suitable journal bearing blocks. The bearing blocks are provided with passage means from the centre bore of the drill string to provide the said air lubrication. The air also serves as a cushion between the roller and the bearings.

Description

United States Patent 1191 White June 28, 1974 [54] ROLLER REAMER STABILIZER 1,812,044 6/1931 Grant 175/346 X 1,938,246 I2 1933 Carlson .1 175/346 X [75] Inventor: Kenneth Calgary 2,122.763 7/1938 Smith 175/346 Alberta, Canada 2,670,046 2/1954 Kinzbach 7. 175/346 x AssigneeZ western Dysart X 4 Limited, Calgary, Alberta, Canada [22] FiledZ Man 12, 1973 Primary Examiner-David H. Brown [2]] Appl. No.: 340,250

[57] ABSTRACT A [30] Foreign pphcauon Prlomy Data A roller reamer stabilizer the bearings of which are lu- DCC. 29, Canada bricated air leed om th Centre o e of t e string. The roller cutters are mounted in recesses in 2? 3533 the body such that the roller cutters are free to rotate i h 75/337 5 324F348 about their bearing pins in suitable journal bearing l 0 an 175/354 blocks. The bearing blocks are provided with passage means from the centre bore of the drill string to pro- 56 R f d vide the said air lubrication. The air also serves as a 1 UNITE]; 52:23; :ZTENTS cushion between the roller and the bearings.

1,139,529 5/l9l5 Hughes 175/345 X 6 Claims, 6 Drawing Figures PATENIEDJUNZB m I SHEET 1 BF- 2 8 v p q \r O O O 0 50 O D O 0 O J 0 0 C O C m 2 VMLI 4 5 r llllll ll 000 O f L llllll oo o 0 6 9 F/GZ ROLLER REAMER STABILIZER BACKGROUND OF THE INVENTION having a balanced life such that the body of the unit 1 matches the life of the roller cutters. It has, however, been found that the units presently in use suffer from premature end wear on the rollers and loosening of their axle shafts.

Expendible roller reamers are generally of two piece construction having a box thread end for attaching the rock bit and a pin thread end for connection to the drill string. The two pieces are connected by pins as in US. Pat. No. 3,306,379 granted to Joseph A. Kloesel, Jr., et al., on Feb. 28, 1967, or by welding. This welded unit generally has the circumferential weld just above the upper end of the axle shaft, such that the lower or box portion of the reamer body has pre-cast recesses for the reamer cutters. The axle shafts are press or shrunk fit into the cast body.

Due to radial impact loads on the reamer cutters, the axle shaft of the expendible reamers tend to loosen such that the axle rotates in the reamer body causing the air lubrication supply hole to be blocked. There is then a rapid heating of the hardened axles and cutter bearing surfaces causing softening such that the abrasion and wear resistance of these components is significantly shortened.

Size limitations and radial loading dictate the amount of space available for the axial thrust on the rollers. The top end of the rollers from field tests show less wear than the bottom end, which would suggest that the rol ler is helddown by its own weight more than it is resisting axial loads as would be encountered in entering an undergauge hole. The abrasion encountered in drilling and the downward weight of the roller is significant enough to cause rapid wear of the roller cutter bottom face and in some instances one-quarter of the roller is gone before the body is appreciably worn.

BRIEF DESCRIPTION OF THE INVENTION The present invention overcomes the problem of roller thrust face wear and loosening of the axle shafts in the body while still maintaining an economical cost balance to make the reamer an expendible item.

For economical reasons, the body of the reamer is preferably an abrasion resistant steel casing having recesses provided for the roller cutters and bearing blocks. The rollers and axle pins become an integral unit having a larger diameter with annual rows of tungsten carbide inserts and two smaller diameters at each end intended to form bearing pins. The bearing pins have a primary thrust face at their outer axial extremities. The bearing. pins are slightly longer than the journal in the bearing block, and there is thus a gap or space between the transitionary plane adjoining the bearing pin on the roller with the larger diameter having the tungsten carbide inserts. The gap is formed between the secondary thrust faces on the roller and the bearing block.

Specific preferred embodiments and innovative features of the invention will now be described with reference to the following drawings, in which,

FIG. 1 illustrates the general configuration of a roller reamer stabilizer according to the invention;

FIG. 2 illustrates an assembled roller and bearing block combination, partially in section prior to mountmg;

FIG. 3 illustrates a centerline section along line 3-3 0 of FIG. 2;

FIG. 4 is a cross-section of a bearing block modifica tion incorporating a bearing sleeve and separate thrust button;

FIG. 5 is an end view of the thrust button shown in FIG. 4; and

FIG. 6 is a cross-section along line 6-6 of the thrust button shown in FIG. 5.

DESCRIPTION WITH REFERENCE TO THE DRAWINGS Referring to FIG. l, the reamer body I is provided with a pin end 2 threaded for releasable attachment to the drill string and a box end 3 for attachment to the drill bit. Bearing blocks 4 and 5 are attached by welding 6 to the reamer body 1. The roller cutter 7 is provided with tungsten carbide inserts as shown 8. Recesses 9 are provided in the body 1 for three roller cutters like 7 such that they are at to one another and are free to rotate.

The assembled roller and block combination shown in FIG. 2 illustrates the gap 10 between the secondary thrust face 11 on the bearing block 13 and the roller 7. This gap is approximately 1/64 inch in the new condition. The sectioned block 13 shows the primary thrust face 14 on the block mating with the primary thrust face 15 on the roller 7. The primary thrust face 15 on the roller cutter pin 7 is an integral part of the pin and is formed with an angled end such as would be formed by the drill utilized in drilling the bearing pin hole in the block. It is therefore preferred that the primary thrust face on the roller cutter bearing pin have a total subtended angle of approximately 120. A further advantage of forming this angled thrust face is that when the bearings are worn the roller will centralize itself on the sloping primary thrust faces and minimize the sliding and rolling contact of the bearing pin of the roller cutter in the journal formed in the block.

The annular rows of tungsten carbide inserts 8 are preferably symmetrical about the midpoint in the roller cutter such that the roller can be turned end for end in the recess in the body. It is further preferred that the end annular rows of

inserts

16, 17, 18, and 19 contain 9 inserts per row and that row 17 be offset 20 from row 16 and row 19 be offset 20 from row 18. The intermediate rows of inserts preferably contain 6 inserts per row and are offset 30 from row to row.

Air lubrication is provided for each bearing pin on the roller cutter through hole 20 as shown in FIG. 3. A corresponding hole is drilled into the center annulus of the reamer body to bleed enough air therefrom to keep the bearing surfaces and thrust faces free from foreign materials. Air lubrication hole 20 in the bearing block should be drilled such that its termination is approximately at the apex of 120 primary thrust face as shown in the sectioned block of FIGS. 2 and 3. Drilling of hole 20 in the aforementioned position tends to create a cushion of air between the primary thrust faces such that there is a shock absorbing effect when the roller cutter is subjected to axial movement. The preferred hole size is inch in diameter in the block and /4 inch in diameter in the reamer body.

FIG. 4 illustrates a bearing block having a wear resistant sleeve 21 either press or shrunk fit into the bearing block body. There is a further modification in that the primary thrust face 22 is flat and is a separate portion of the bearing rather than part of the bearing block. The thrust button 23 has the primary thrust face 22 carburized and hardened. The use of a bearing sleeve 21 and thrust button 23 as shown in FIG. 4 eliminate carburizing and hardening of the bearing surfaces as would be required in a block of the type shown in FIGS. 2 and 3 but manufacturing costs tend to be somewhat higher.

Referring to FIGS. and 6, air lubrication is provided through

relieved areas

24 and 25 to the primary thrust face by hole 26. Relieved area 24 is sized such that when thrust button 23 is installed in a block according to FIG. 4 air passageway 27 is not blocked and air from the center annulus of the tool body is directed on to the center of the roller cutter bearing pin through the aforementioned passageways and relieved areas.

What I claim as my invention is:

l. A roller reamer adapted for releasable attachment to a tubular drill string in which air flows through a center bore and drill bit cuttings are removed up an annular space between the rock bore and the drill string, said roller reamer having a tubular body with a plurality of roller cutters mounted in recesses in said body such that said roller cutters are free to rotate about integral bearing pins in suitable journal bearing blocks. said journal bearing blocks being provided with air passage means from the center bore to provide air lubrication to the journal and bearing pin surfaces.

2. A roller reamer according to claim I in which said roller cutters have a major diameter provided with annular rows of tungsten carbide inserts and two minor diameters forming bearing surfaces, said major and minor diameters being joined by a transitionary surface substantially perpendicular to the longitudinal axis of the reamer and said transitionary surface fonning a secondary thrust face.

3. A roller reamer according to claim 1 in which said roller cutter bearing pins have at their outer longitudinal extremities a primary thrust face.

4. A roller reamer according to claim 3 in which the air passage means in said journal bearing blocks are disposed so that air may be bled from the center bore to the primary thrust faces on the roller cutter bearing pins.

5. A roller reamer roller cutter according to claim 3 in which the primary thrust face is provided with self centering means consisting of a convex conical primary thrust face mating with a concave conical thrust face in said journal bearing block.

6. A roller reamer having journal bearing blocks according to claim 4 in which said air lubrication passageway provided terminates substantially at the apex of said concave conical thrust face.

Claims

1. A roller reamer adapted for releasable attachment to a tubular drill string in which air flows through a center bore and drill bit cuttings are removed up an annular space between the rock bore and the drill string, said roller reamer having a tubular body with a plurality of roller cutters mounted in recesses in said body such that said roller cutters are free to rotate about integral bearing pins in suitable journal bearing blocks, said journal bearing blocks being provided with air passage means from the center bore to provide air lubrication to the journal and bearing pin surfaces.

2. A roller reamer according to claim 1 in which said roller cutters have a major diameter provided with annular rows of tungsten carbide inserts and two minor diameters forming bearing surfaces, said major and minor diameters being joined by a transitionary surface substantially perpendicular to the longitudinal axis of the reamer and said transitionary surface forming a secondary thrust face.