Universal Saddle Mounting For Fixed And Rolling Cutters

Abstract

The present invention relates to non-rolling or fixed cutter assemblies and supports for such assemblies for use on tunneling machines, raise drilling machines and other types of earth boring equipment. In particular the invention relates to cutter supports adapted for removably mounting either rolling or fixed cutter assemblies and to fixed cutter assemblies adapted for mounting in the supports. A fixed cutter assembly and support according to the invention comprises fixing means, including a fixing surface integral with the cutting element of the cutter assembly, for releasably fixing the cutting element against rotation relative to the support.

Description

BACKGROUND OF THE INVENTION

In mining, construction, and other industries involving earth boring operations, the use of heavy duty machines for boring earth and rock formation has become increasingly popular and has, to a great extent, replaced hand mining. The present invention relates to such machines and especially to those for drilling large diameter holes. Such holes, if substantially horizontal, are referred to as tunnels, and if substantially vertical, are often referred to as raises or winzes.

Machines of this type generally comprise a large rotary bit or cutterhead which is rotated and simultaneously pulled or pushed through the formation by the machine. Mounted on the bit facing the formation to be bored are a plurality of cutters. These cutters may be of two basic types: rolling cutters and fixed cutters. Rolling cutters are mounted for rotation about shafts which extend generally radially from the axis of the cutterhead so that when the cutterhead is rotated, the cutters will roll against the rock or earth formation to be bored. Fixed cutters do not move relative to the cutterhead and operate like blades which are dragged or scraped against and into the formation as the bit rotates. The type of cutters to be used in any particular case is determined by factors such as the nature of the hole to be drilled, the make-up of the formation, etc. In tunnel boring, for example, it is often desirable to use a mixture of fixed and rolling cutters on the same bit. However, as the drilling progresses different types of formation may be encountered rendering the types of cutters and their arrangement on the bit less effective.

U.S. Pat. Nos. 2,811,341 and 3,139,148 show cutterheads of tunneling machines having both rolling and single blade fixed cutters mounted thereon. U.S. Pat. No. 3,203,492 shows a drill bit having rolling type cutter assemblies adapted for mounting on a type of support often referred to as a "saddle."

The supports or saddles shown and described in U.S. Pat. No. 3,203,492 comprise a pair of generally parallel arms connected at respective aligned ends by a rigid connecting portion to form with the inner surfaces of the arms a generally U-shaped surface. Rigidly adjoining the connecting portion opposite the U-shaped surface is a base portion adapted for mounting on a drill bit. The rolling cutter assembly used with this type of support includes a wheel-like or roller-like cutting element which rotates about a shaft. The ends of the shaft protrude from the ends of the cutting wheel to engage holding means on the inner surfaces of the support arms so that the cutter assembly is supported for rotation between the arms at a given location therealong. The support arms and the ends of the cutter assembly shaft also include end locking means for limiting relative rotation therebetwen. The cutter supports become a relatively permanent part of the bit, while the rolling cutter assemblies are easiy removable for replacement or repair.

SUMMARY OF THE INVENTION

The present invention relates to fixed cutter assemblies adapted to be mounted in supports which can alternatively mount rolling cutters.

The fixed cutter assemblies of the present invention each comprise a cutting element having a longitudial centerline. The cutting element includes at least one cutting structure extending generally outwardly away from the centerline. The cutter assembly further includes at least one bearing end and preferably a pair of bearing ends located at opposite ends of the cutting element. These bearing ends are analogous to the ends of the shaft in a rolling cutter assembly and can be engaged by the holding means on the support which ordinarily hold the shaft ends of the rolling cutter. The cutter assembly has a fixing or rotation limiting surface rigidly carried on the cutting element. When the cutter assembly is placed in the support, the fixing surface is engageable with a fixed surface on the support. Together, the fixing surface and engaged fixed surface of the support form fixing means to fix the cutting element against rotation relative to the support. In some embodiments of the invention, the support must be modified to provide for the fixing means. Such modification however does not effect its ability to mount rolling cutter assemblies interchangeably with the fixed cutter assemblies. The bearing ends of the fixed cutter assembly preferably include means similar to those on the shaft ends of the rolling cutter which lock with mating means on the support to prevent relative rotation between the bearing ends and the support arms.

The present invention also encompases a fixed cutter assembly whose cutting element includes a plurality of circumferentially spaced cutting structures and means by which any desired one of these cutting structures can be fixed in cutting position. The invention also includes forms in which the entire cutting element and/or portions of its cutting structure are replaceable. Additionally, the entire cutter assembly can be quickly and easily removed from the support and replaced by another assembly.

It will be readily appreciated that in accord with the present invention fixed cutter assemblies are provided for mounting in supports which can also mount rolling cutter assemblies interchangeably with the fixed cutter assemblies. This considerably increases the usefulness of a given bit as it can be adapted for many different rock and earth formations. Thus, the bit can be adapted for different jobs or for different formations which may be encountered as a long hole is being drilled. When fixed cutter assemblies are used, the bit is made further adaptable for different drilling conditions since cutting structures of different configurations can be provided by re-positioning the cutting element, replacing the cutting element, or replacing the entire assembly in the support.

Further advantages are afforded by the fact that the fixed cutter assembly is removable from the support and part or all of the cutting element is replaceable. This makes for minimum repair or replacement costs when part or all of a cutter assembly becomes worn or damaged.

It is thus a principal object of the present invention to provide a fixed cutter assembly removably mountable in a support.

Another object of the invention is to provide a cutter support and both fixed and rolling cutter assemblies adapted for mounting therein.

One more object of the invention is to provide a fixed cutter assembly having a plurality of cutting structures, any one of which can be fixed in cutting position in a support.

Still another object of the invention is to provide a fixed cutter assembly having replaceable cutting structure.

Other objects and advantages of the invention will be made apparent by the following detailed description and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view partly in section and partly in elevation, with parts broken away, showing one form of fixed cutter assembly mounted in its support.

FIG. 2 is a view taken along lines 2--2 in FIG. 1.

FIG. 3 is an elevational view of the inner surface of the support arm of FIG. 2.

FIG. 4 is a view partly in section and partly in elevation of another form of cutter assembly mounted in its support.

FIG. 5 is a cross sectional view taken along lines 5-- 5 in FIG. 4.

FIG. 6 is a view partly in section and partly in elevation of a third form of cutter assembly mounted in the support of FIG. 4.

FIG. 7 is a cross sectional view taken along lines -- 7 in FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

For purposes of illustration, the present invention will be described as it pertains to the saddle type cutter supports shown in U.S. Pat. No. 3,203,492. However it will be readily appreciated that the invention can be applied to any type of support for mounting roller cutters. To the extent to which it relates to the present invention, the disclosure of U.S. Pat. No. 3,203,492 is hereby expressly incorporated herein by reference.

FIGS. 1- 3 depict one embodiment of the invention in which a support similar to those shown in U.S. Pat. No. 3,203,492 is slightly modified to accommodate a fixed cutter assembly but without altering its ability to accommodate a rolling cutter assembly interchangeably with the fixed cutter assembly.

Referring to FIG. 1, the fixed cutter assembly 10 is shown mounted in the support l2. The support 12 comprises a pair of substantially parallel arms 14, 16 having respective inner surfaces 18, 20 facing each other. The arms 14 and 16 are connected at their lower ends by a connecting portion 22 which forms, with the inner arm surfaces 18 and 20, a U-shaped surface 24. the support also includes a base portion 26 integral with connecting portion 22 and opposite the U-shaped surface 24. In use the base portion 26 is rigidly attached to a drill bit or cutterhead (not shown) as by welding or bolting.

The arms 14, 16 have respective axially aligned bores 28, 30 extending therethrough near their upper ends. Arms 14, 16 also have respective axially aligned holes 32, 34 extending therethrough. Holes 32, 34 are located between the connecting portion 22 and the bores 28, 30, and each of the bores 28, 30 and holes 32, 34 extends in the same general direction as the connecting portion 22.

The inner surfaces 18 and 20 of arms 14 and 16 have respective dovetail grooves 36, 38 which serve as holding means to receive the bearing ends 40, 42 of the fixed cutter assembly 10 and threby support the cutter assembly at a given location along arms 14, 16 and therebetween as shown.

The bearing ends 40 and 42 form the ends of a shaft 44 which extends through a longitudinal bore in the cutting element 46. The cutting element 46 seats against a shoulder 48 on the shaft 44 so that the bearing ends 40 and 42 protrude from the ends of the cutting element. In order to retain the bearing ends 40,42 in the grooves 36, 38, a main pin 64 is inserted in bores 28, 30 and through an aligned longitudinal passageway 66 in the shaft 44. Thus the cutter assembly 10 is held in the support 12 no matter which way the support may be turned. Main pin 64 is held against endwise movement by a roll pin 68 extending transversely through main pin 64 and arm 14. The shaft 44 serves as a pivot means for the cutting element 46, which is rotatable about the shaft. The cutting element 46 has a longitudinal centerline c therethrough and includes two cutting structures extending generally outwardly away from centerline c. It should be noted that the term "centerline" is used herein to denote a line extending through the centers of the bearing ends and does not necessarily denote a true center of the cutter assembly as a whole. The cutting structure which is shown in operating position in FIGS. 1 and 2 is comprised of a wing 50 and four cutting picks 52. The wing 50 extends generally outwardly from centerline c away from connecting portion 22 at a suitable angle. The picks 52 extend outwardly from the wing 50 at an angle of approximately 90.degree. thereto. Of course, the exact angle is a matter of individual design. The picks 52 may be pressed into wing 50 or otherwise secured so that they can be removed and replaced when worn. Or they may be formed integrally with wing 50. Wing 50 has a hole 54 therethrough extending in a direction substantially parallel to the centerline c. The other cutting structure is comprised of the three harrow-tooth type blades 56 located generally opposite the first cutting structure. Blades 56 also have aligned holes 58 therethrough substantially parallel to the axis c.

When the first cutting structure is in operating position as shown, the holes 58 are aligned with the holes 32 and 34 in the support arms 14 and 16. A torque reaction bar 60 is inserted through holes 32, 58, and 34 and is held against endwise movement by a roll pin 62 extending transversely through bar 60 and arm 14. The surfaces of the holes 58 serve as fixing surfaces and cooperate with the torque reaction bar 60 to form fixing means which prevent rotation of the cutting element 46 about the shaft 44 and keep the first cutting structure in operating position. Similarly, when the second cutting structure is used, the hole 54 is aligned with holes 32, 34 in the arms, and the torque reaction bar 60 is inserted through holes 32, 54, and 34 to keep the cutting element in position.

It will readily be appreciated that many modifications of the cutting element are possible. For example, the cutting element shown has cutting structures of two different types so that the assembly can be quickly and easily adapted for different drilling conditions. However, the cutting structures could be made identical so that when one is worn, the other can be placed in operating position. The types of cutting structures could also be varied and any other cutting structure could be employed.

The number of cutting structures on the cutting element could also be varied to include more than two. Or a cutting element might be provided with only one cutting structure. In the latter case, a suitable projection located generally opposite the cutting structure could be provided and this projection could have a hole therethrough aligned with holes 32, 34 for receipt of the torque reaction bar.

It will also be recognized that, because the cutting element is removable from the shaft, it can be replaced when worn or damaged or when a different type cutting structure is needed without the need for replacing the entire assembly.

In preferred forms of the invention the bearing ends 40, 42 and the respective support arms 14, 16 have end locking means for preventing relative rotational movement. While any suitable type of end locking means could be employed, the type illustrated in FIGS. 2 and 3, known as an eccentric lock, is highly effective. As best seen in FIG. 3, the bottom of the groove 38 in arm 16 is arcuate, having a center g which will be referred to as the center of groove 38. The sides of the groove are straight and extend from the opposite ends of the arcuate portion in the same direction and substantially parallel to each other. The bore 30 has a center b which is offset from the center g in a direction generally normal to the sides. The bore 28 in arm 14 is similarly offset from the center of the bottom arc of groove 36 so as to be aligned with bore 30. Referring now to FIG. 2, it will be seen that the centerline c lies along the center of the shaft 44. The center p of the passageway 66 is offset from centerline c just as center b is offset from center g. When the cutter assembly is placed in the support, the shaft 44 is turned until passageway 66 is aligned with bores 28 and 30. Then the main pin 64 is inserted through the bores 28 and 30 and the passageway 66. When a load is placed on the cutting structure in operation, a torque is transmitted to the shaft 44. Because of the presence of the main pin 64, the shaft 44 tends to rotate about an axis through center p rather than about its own centerline c. Thus the edges of the bearing ends 40, 42 are eccentrically locked against the surfaces of the grooves 36, 38.

FIGS. 4- 7 show two other forms of the invention. In each of these two forms the cutting element is integrally connected to the bearing ends so that the main pin serves as the pivot means for the cutting element. Because the bearing ends and cutting element are integral in these forms, the end locking means on the bearing ends and support arms also serve as the fixing means which fix the cutting element against rotation relative to the support. Each of the two forms of FIGS. 4- 7 employs the eccentric type lock and the fixing surfaces are comprised of the edges of the bearing ends. However, it will be appreciated that the same principle may be applied to any other type of end locking means.

In particular, FIGS. 4 and 5 show a form in which the cutting element 70 and bearing ends 72, 74 are formed in one integral piece except for the picks 76 which can be removed and replaced. Cutting structures other than the pick type shown could also be used. The cutting element 70 and the bearing ends 72, 74 have a longitudinal passageway 78 therethrough whose center p.sub.1 is offset from the centerline c.sub.1 of the cutting element. centerline c.sub.1 passes through the centers of the bearing ends 72, 74.

The support 80 is substantially identical to the suspport 12 of FIGS. 1- 3 except that it does not have holes such as 32 and 34. Support 80 comprises arms 82 and 84, connecting portion 86 and base portion 88. The arms 82 and 84 have respective dovetail grooves 90 and 92 on their inner surfaces which serve as holding means to engage the bearing ends 72 and 74. The lower portions of grooves 90 and 92 are arcuate and have axially aligned centers (not shown). Axially aligned bores 94, 96 extend through the arms 82, 84 in the area of the dovetail grooves 90, 92 and have centers (also not shown) which are offset from the centers of the arcuate portions of the grooves.

In mounting the cutter assembly in the support, the bearing ends 72, 74 are seated in the grooves 90, 92 and the cutting element is rotated until passageway 78 is aligned with bores 94 and 96. A main pin 98 is then inserted through the bores 94 and 96 and the passageway 78 and retained against endwise movement by roll pin 100 which passes transversely through main pin 98 and support arm 82. When the cutting structure is loaded in operation a torque is placed on the cutting element 70 and it rotates a few degrees about the main pin 98 until the edges of the bearing ends 72 and 74 become eccentrically locked against their respective grooves 90 and 92 in the support arms. It will be understood that the cutting structure is oriented so that it will be in proper position for drilling when the cutting element is in its locked position.

The embodiment of FIGS. 6 and 7 is similar to that of FIGS. 4 and 5. However in the embodiment of FIGS. 6 and 7 the bearing ends 102, 104 are integral with a shaft 106 which extends through the annular cutting element 108. The cutting element 108 seats against a shoulder 110 of the shaft 106 and is integrally connected to the shaft by press fitting, heat shrinking, welding, or other suitable means. Thus it can be cut away or otherwise removed and replaced when worn. The cutting structure as shown is comprised of harrow tooth blades 112, but of course any desired cutting structure can be used.

The cutting element 108 has an axis c.sub.2 passing through the centers of the bearing ends 102 and 104, and the shaft 106 has a longitudinal passageway 114 therethrough whose axis p.sub.2 is offset from centerline c.sub.2.

The support 80 is identical with that of FIGS. 4 and 5. Thus bearing ends 102 and 104 can be seated in the grooves 90 and 92 and passageway 114 can then be aligned with the bores 94 and 96. The main pin 116 can then be inserted through bores 94 and 96 and passageway 114 and retained by roll pin 118. Eccentric locking of the bearing ends in the grooves and resultant fixing of the cutting element against rotation is effected by the load on the cutting structure in the same manner as in the embodiment of FIGS. 4 and 5 above.

Claims

We claim:

1. A rolling cutter assembly support and fixed cutter assembly combination comprising: a rolling cutter assembly support having a base portion adapted to be secured to a bit body, holding means on said support spaced from said base portion engageable with a non-rotating part of a rolling cutter assembly to rotatably support a cutting element of said rolling cutter assembly; and a non-rotating cutter assembly having a mounting part compatible with and mounted on said holding means and also having a cutting structure projecting from said holding means in a direction away from said base portion; a fixed surface on said cutter support and a fixing surface on said non-rotating cutter assembly engageable with said fixed surface to prevent said cutting structure from rotating relative to said support.

2. A non-rolling cutter assembly adapted to be mounted on a rolling cutter assembly support for use on a bit body, said non-rolling cutter assembly comprising: a cutting element having a longitudinal centerline therethrough and a cutting structure extending generally outwardly away from said centerline; pivot means carried on said cutting element; a fixing surface integrally connected to said cutting element and radially outwardly spaced from the axis of said pivot means, said fixing surface being adapted to engage a fixed surface separate from said non-rolling cutter assembly to limit pivotal movement of said cutting element about the pivot means; and a first bearing end at one end of said cutting element.

3. A non-rolling cutter assembly according to claim 2 including a second bearing end at the other end of said cutting element, said bearing ends being rigidly attached to said cutting element.

4. A non-rolling cutter assembly according to claim 3 having a longitudinal passageway therethrough extending through said bearing ends parallel to said axis but eccentric with respect to said centerline, and wherein said pivot means comprises a pin extending through said passageway.

5. A non-rolling cutter assembly according to claim 3 wherein said bearing ends are integral with and located at opposite ends of a bearing shaft extending longitudinally through said cutting element, said cutting element being rigidly attached to but removable from said bearing shaft.

6. A non-rolling cutter assembly according to claim 2 wherein said cutting structure includes a plurality of replaceable cutting picks.

7. A non-rolling cutter assembly according to claim 2 including a second bearing end at the other end of said cutter element, a bearing shaft integrally connecting said bearing ends, said cutting element being rotatably mounted on said shaft, said cutting element further having a hole therein for receipt of a torque reaction bar.

8. A non-rolling cutter assembly according to claim 7 where said bearing shaft has a longitudinal passageway therethrough generally parallel to said centerline but eccentric with respect to said centerline, and wherein said bearing shaft is concentric with said centerline, said cutter assembly further comprising a pin extending through said passageway.

9. A non-rolling cutter assembly according to claim 7 wherein said cutting element includes a plurality of such cutting structures circumferentially spaced from one another, and wherein said cutting element has a plurality of such holes therein corresponding to the number of cutting structures.

10. A non-rolling cutter assembly according to claim 7 wherein said hole extends through said cutting element in a direction generally parallel to said centerline and is spaced radially outwardly from said bearing ends.

11. A non-rolling cutter assembly according to claim 7 wherein said cutting structure includes a plurality of replaceable cutting picks.

12. A rolling cutter assembly support having a non-rolling cutter assembly removably mounted therein, said support comprising: a pair of spaced apart support arms each having an inner surface, said inner surfaces facing each other and being generally parallel, said arms further comprising holding means supporting said non-rolling cutter assembly at a given location along said arms, said holding means also being engageable with a non-rotating part of a rolling cutter assembly to rotatably support a cutting element of said rolling cutter assembly; base means rigidly adjoining respective aligned ends of said arms and adapted for rigidly attaching said arms to a drill bit in fixed position relative to each other; and means for releasably fixing a cutting element of said non-rolling cutter assembly against rotation relative to said support.

13. The apparatus of claim 12 wherein said non-rolling cutter assembly has a longitudinal centerline extending between said support arms, a pair of bearing ends each engaged by the holding means on one of said arms, and said cutting element of said non-rolling cutter assembly is located between said bearing ends and includes a cutting structure extending outwardly away from said centerline, and wherein at least one of said support arms and its engaged bearing end have end locking means for limiting relative rotation therebetween.

14. The apparatus of claim 13 wherein said bearing ends are integrally attached to said cutting element of said non-rolling cutter assembly and wherein said end locking means also serve as said fixing means.

15. The apparatus of claim 14 wherein said bearing ends are integral with and located at opposite ends of a bearing shaft extending longitudinally through said cutting element of said non-rolling cutter assembly, said cutting element of said non-rolling cutter assembly being integrally attached to, but removable from, said bearing shaft.

16. The apparatus of claim 13 wherein said bearing ends are integral with and located at opposite ends of a shaft extending longitudinally through said cutting element of said non-rolling cutter assembly, said cutting element of said non-rolling cutter assembly being rotatable about said shaft.

17. The apparatus of claim 16 wherein said cutting element of said non-rolling cutter assembly includes a plurality of circumferentially spaced cutting structures and is rotatable into a plurality of positions in said cutter support, each of said positions orienting one of said cutting structures so that it extends generally outwardly from said support in a cutting position, the apparatus further including a plurality of such fixing means for fixing said cutting element of said non-rolling cutter assembly in each of said positions.

18. The apparatus of claim 16 wherein the fixing means comprises a torque reaction bar, wherein said support has a hole therein for receipt of said torque reaction bar, said cutting element of said non-rolling cutter assembly also having a hole therein for receipt of said torque reaction bar, said apparatus further comprising means for preventing endwise movement of said torque reaction bar.

19. The apparatus of claim 13 wherein said non-rolling cutter assembly has a longitudinal passageway therethrough extending through said bearing ends, said bearing ends being concentric with said centerline and said passageway being eccentric with respect to said centerline, wherein each of said support arms has a groove on its inner surface partially surrounding its engaged bearing end, each of said arms further having a bore therethrough of substantially the same diameter as the passageway through the cutter assembly, said bore being substantially parallel to the cutter assembly centerline and being eccentric with respect to a center of said groove, wherein said bores are axially aligned with each other, and wherein said apparatus further includes a pin extending through said bores and said passageway such that a force tending to rotate said bearing ends with respect to said support arms will cause them to become eccentrically locked on said grooves against such rotation, and means preventing endwise movement of said pin.

20. The apparatus of claim 19 wherein said cutting structure is oriented at an angle such that the load on the cutting structure during drilling tends to eccentrically lock said bearing ends against rotation relative to said support.

21. A rolling cutter assembly support comprising: a pair of support arms each having an inner surface, said inner surfaces facing each other and being generally parallel, said arms further comprising holding means for supporting a non-rolling cutter assembly to be mounted in said support at a given location along said arms, said holding means also being engageable with a non-rotating part of a rolling cutter assembly to rotatably support a cutting element of said rolling cutter assembly; base means rigidly adjoining respective aligned ends of said arms and adapted for rigidly attaching said arms to a drill bit in fixed position relative to each other; and a releasable fixing member adapted for fixing said cutter support to a cutting element of a non-rolling cutter assembly to be mounted in said support.

22. The support of claim 21 having a hole therein and wherein said fixing member comprises a torque reaction bar insertable into said hole said support further comprising means for preventing endwise movement of said torque reaction bar.

23. The support of claim 22 wherein both of said arms have such holes extending therethrough, said holes being axially aligned and extending in the general direction of said connecting member and said torque reaction bar being sized to extend through both of said holes.

24. The support of claim 21 including a connecting portion integral with said base means and rigidly connecting said respective aligned ends of said arms.