A ROTARY CUTTERHEAD FOR AN EARTH BORING MACHINE

Abstract: The main frame of the cutterhead (20) comprises a plurality of radial spoke beams (48) which are interconnected between a box-like hub structure (32) and an annular box beam (60) by which the cutterhead is mounted for rotation. Cutter mounting wells are defined by and between side wall portions (50, 52) of the radial spoke beams (48). The mined material passes rearwardly through the cutterhead via openings between adjacent radial spoke beams and open spaces in the cutter mounting wells. Cutter mounts (99) span laterally between the side wall portions (50, 52) and laterally brace the radial spoke beams (48) in addition to mounting the cutters (26). The radial spoke beams (48) curve rearwardly at their outer ends and connect to the annular box beam (60) at a location spaced enough rearwardly from the front portions of the spoke beams (48) such that an interior space (IS) is defined within the cutterhead. Roller type cutters (26) are installed onto and removed from the cutterhead frame from the rear side of the cutterhead.

Description: A ROTARY CUTTERHEAD FOR AN EARTH BORING MACHINE The present invention relates to rock boring machines, and in particular to a new cutterhead construction for such a machine. U. S. Patent No. 3 . 756,332 discloses a popular open face cutterhead and a typical cutter arrangement on a cutterhead. The cutterhead includes a plurality of disc cutter assemblies pos¬ itioned for cutting concentric kerfs in the rock. The disc cutters include sloping breaker surfaces flanking circumferential cutting edges. These breaker surfaces serve to fracture and dislodge the rock material between kerfs which are cut by the cutting edges. The cutter assemblies are mounted onto the front side of the cutterhead. Most of them are mounted on the front walls of radial spoke beams, while others are mounted on the front side of auxiliary frame structure that is angularly offset from the radial spoke beams. A disadvantage of this type of arrangement is that whenever it is necessary to replace the cutters, which is a fre¬ quent occurrence, it is necessary to back the cutterhead up from the tunnel face and then send a workman into the quite dangerous region forwardly of the cutterhead. It is known to mount the cutters onto the rear side of the cutterhead so that cutter replacement can be made in relative safety behind the cutterhead. However, such rear mounting is most normally associated with closed face cutterheads and has not been used with open face cutterheads. The term "open face tunneling machine" is used herein to mean a cutterhead comprising a plurality of radial spoke beams on which most of the cutters are mounted, with spaces being provided between adjacent beams through which the mined material passes. In a closed face cutterhead the mined material is picked up only at the periphery of the cutterh except for pieces which are small enough to pass through the sma spaces which exist about each roller cutter element. Examples of rear mounting of roller cutters onto soli face cutterheads, existing in the patent literature, are disclos by U. S. Patnet Nos. 3.358,782 and 3, ,939. For some types of tunnel boring jobs the open face or spoke style of cutterhead possesses advantages over the closed f style of cutterhead in that the cut material can pass through th cutterhead at almost any level of the tunnel face and need not f down to be picked up by peripheral buckets. The object of the present invention is to provide an improved open face type cutterhead on which all of the roller cu including a center cutter assembly and gauge cutters, are remova from the back side of the cutterhead. Accordingly, the present invention provides a main fr for a rotary cutterhead of an earth boring machine, said main fr comprising an annular beam by which the cutterhead is mounted on an earth boring machine, for rotation about an axis of rotation; box-like hub structure comprising peripheral wall means defining center space; a plurality of radial spoke beams having inner end which are integrally connected to the peripheral wall means of the hub structure and outer ends which are integrally connected the annular beam, each said radial spoke beam comprising a pair spaced apart side plate members and wherein each radial spoke be extends rearwardly of the hub structure as it extends radially o wardly from the hub structure to the annular beam. In a preferred embodiment, roller type cutters are mo between the side plate members by cutter mounts which extend tra versely of the radial spoke beams and are integrally connected a their ends to the spaced apart side plate members, to also funct as structural brace members for the radial spoke beam. The cutt mounts are adapted for installation and removal of the roller cu from the rear side of the cutterhead and the main frame provides space inside the cutterhead large enough to provide room for in¬ stallation and removal of the roller cutters from behind the cut head. The side plate members extend generally vertically at the C PI before connecting to the annular beam. The gauge cutters are mounte between the rearwardly extending outer end portions of the side plat members of at least some of the radial spoke beams. Installation and removal paths for the gauge cutters extend generally vertically in a region of the interior space that is located forwardly of the annular beam and rearwardly of the front portions of the radial spoke beams. A center cutter assembly is preferably mounted within the interior of the hub structure. A conveyor for removing mined material rearwardly from the region of the cutterhead and its col¬ lector structure may be mounted for movement between a forward position in which the collector structure is in a collecting pos¬ ition adjacent the rear side of the cutterhead and a retracted position in which enough clearance is provided forwardly of it to allow installation and removal of the center cutter assembly. The main frame of the cutterhead is relatively simple and the side plate members which define the radial spoke beams, and the cutter'mount structure therein, perform the second func¬ tion of mounting the roller cutters for easy removal from the rear side of the cutterhead. The rearwardly curved nature of the outer end portions of the side plate members provides the necessary room within the cutterhead to permit installation and removal of the gauge cutters from behind the cutterhead and also strengthens the peripheral region of the cutterhead. The edgewise orientation of the side plate members relative to the thrust forces imposed on the radial spoke beams contributes to the beams being relatively strong while relatively simple in construction. The annular beam to which the radial spoke beam side plate members are connected is preferably a box beam which provides a quite strong and rigid collector for the forces which are imposed on the radial spoke beams and " ,evenly distribute such forces to the combination thrust and radial bearing which serves to mount the cutterhead for rotation. In the drawings in which like element designations refer to like parts throughout: FIG. 1 is a fragmentary side elevational view, with some parts in axial section, of a tunnel boring machine which in¬ cludes a cutterhead exemplifying an embodiment of the present invent ion, with the portion of the machine which is disposed rearwardly of the mid-portion of the gripper as sembly being omitted . FIG. 2 is a ' front eleva tional view of the cutterhead of Figure 1; FIG. 3 is a sectional view taken through the boring machine substantially along line 3-3 of FIG. 1, showing the rear side of the cutterhead support in elevation; FIG. 4 is a cross-sectional view taken substantially along line 4-4 of FIG. 1, showing the gripper assembly in eleva¬ tion, with some parts broken away for clarity of illustration of other parts; FIG. is an isometric view taken from the front and looking down towards an upper portion and a side portion of the basic cutterhead frame, with a foreground portion of such frame being cut away; FIG. 6 is a view similar to FIG. 5, but looking toward the rear side of the basic cutterhead frame, with an upper fore¬ ground portion of such frame being cut away for clarity of illus- tration of certain parts; FIG. 7 is a fragmentary isometric view of the hub region of the cutterhead frame, taken from the rear of the cutterhead; FIG. 8 is a fragmentary elevational view of the center region of the cutterhead, with some parts in section; FIG. 9 is a sectional view taken substantially along line 9-9 of FIG. 8; FIG. 10 is a fragmentary isometric view of the center region of the cutterhead, taken from behind the cutterhead, with the center cutter exploded out from its mounted position; FIG. 11 is a fragmentary view, partially in section and partially in elevation, of an intermediate cutter, showing a way of mounting the cutter; FIG. 12 is a split sectional view, the upper portion being taken along line 12a - 12a and the lower portion along line 12b - 12b, of FIG. 11; FIG. 13 is an exploded isometric view of an intermedia cutter and its mounting structure; OMPI WIPO FIG. 14 is a fragmentary view of that portion of FIG. 1 in the vicinity of the forward end of the conveyor, with the conveyor being shown in a retracted position back from the inner side of the cutterhead, and including a broken line showing of the forward or in use position of the conveyor; and FIG. 15 is a sectional view taken substantially along line 15-15 of FIG. 14, showing the mechanism which mounts the front end of the conveyor. Referring to FIG. 1, the tunneling machine itself is of the rotary cutterhead hard material disintegrating type. The advance direction is coincident to the rotary axis of the cutter¬ head and the tunneling machine follows the cutterhead into the opening formed thereby. The basic parts of the tunneling machine are a main frame which includes a cutterhead support 10 attached to a tubular shield 12 and a rearwardly projecting beam 14. A gripper assembly 16 is supported for relative sliding movement along a straight por¬ tion of the beam 14. Thrust rams 18, located on both sides of the machine, are interconnected between the cutterhead support 10 and the gripper assembly 16. As is well known in the tunneling machine art, the gripper assembly lβ is positioned forwardly on the beam 14. Its gripper shoes 17 are hydraulically moved outwardly into gripping contact with the side walls of the tunnel. Then, the thrust rams 18 are extended while the rotary cutterhead is being rotated by means of a plurality of drive motors 22. Motors 22 drive circular gears (not shown) which mesh with a large diameter gear 24 that is an integral part of the rotating cutterhead 20. When the cylinders l8 reach the forward limits of travel the gripper pads 17 are re- tracted and the cylinders 18 are retracted for the purpose of draw- ing the gripper assembly forward into a new position. Then, the gripper pads 17 are again moved outwardly into contact with the tunnel wall and the boring procedure is repeated. Roller cutters 2β, 28, 30 (FIG. 2) are used and the ar¬ rangement or pattern of these cutters may be basically like what is shown by U. S. Patent No. 3 . 756,332. The disc cutters are arranged to cut concentric kerfs (e.g. spaced 2 3/4 inches - 4 inches apart) and to fracture the rock between kerfs. The roller cutters 26, 28 GMPI . WWIIPPOO 30 may be installed onto and are removable from the cutterhead 2 from the rear side of the cutterhead 20. This makes it unnecess for the tunneling machine to be backed up and for a workman to g down into the very hazardous region between the front of the cutterhead and the tunnel face for the purpose of changing cutte As we discussed above, the general idea of mounting cutters onto a cutterhead from the rear is not new, but the dis¬ closed construction of the cutterhead to facilitate such assembl and removal is new. Also, such construction allows rear install tion and removal of the gauge cutters as well as the face cutter this capability is new. The frame of the cutterhead comprises a box-like hub structure 3 which may be a one-piece casting. Hub structure 32 preferably is of a generally hexahedral form and comprises six peripheral walls 34, 36, 38, 40, 42, 44 and a front wall 46 (FIG URES 2 and 5). In larger cutterheads the number of radial spoke may be increased to eight. In smaller cutterheads the number ma be reduced to four, for example. A window 47 is provided in the front wall 46 and the rear side of hub structure 3 is open. A plurality of radial spoke beams 48 are integrally welded to the hub structure 32 generally at the corner regions where the walls 34, 36, 38, 40, 42, 44 meet each other. As shown best by FIG. 7 radial stub walls may be provided at the corners. Each radial s beam 48 comprises a pair of spaced apart steel plate side walls 52. The inner ends of side walls 50, 52 abut against end or sid portions of the stub walls and are welded thereto. Each side wa 50, 52 occupies a plane which is substantially parallel to the t nel axis. Thus, it can be said that in the fore and aft directi the side walls 50, 52 are parallel to each other and to the tunn axis. For the most part the beams 48 are open both front and re so that a front to rear open space exists between their side wal 50, 52. Spaces also exist between adjacent beams 48. The front edges of the side plate members 50, 52 clos follow the desired contour of the tunnel face. As best shown by FIG. 1, this shape is preferably a relatively flat crown shape w a generally circular curvature existing at the outer regions. As shown by FIGS. 1, and 6, the side plate members 52, extend generally radially outwardly from the center hub stru 32 and in their outer regions curve rearwardly about ninety degrees. The upper rear ends of the side plate members 0, 52 are integrally attached to a frusto-conical shape forward wall 58 of an annular box beam 6θ. Box beam 6θ also includes a f usto-conical peripheral wall 62, a frusto-conical upper rear wall 64, a mounting ring 66, which is also a lower rear wall, and a cylindrical inner wall 68. Of course, in other installations this construction of the annular box beam could be different. The illustrated configuration of the side walls 50, 52 results in radial beams 48 which are quite strong in the direction of the thrust loads applied to them, since the side walls extend edgewise to the direction of thrust loading. Also, the configura¬ tion of side walls 50, 52 and their location of connection with the annular box beam 6θ results in a space existing between each pair of side walls 5°, 52, throughout the full extent of beams 48, i.e. from where they are connected to the center hub member 32 out to where they are connected to the annular box beam 60, in which the roller cutters are mounted. Such configuration of side walls 0, 52 and location of attachment of the side walls 50, 52 to the beam 60 also provides a sufficient amount of interior space IS (FIG. 1) within the cutterhead 20 to allow installation and removal of all of the cutters from behind the cutterhead. Installation and removal paths for the gauge cutters 30 are defined in a generally vertical direction, forwardly of the box beam forward wall 58. The cutterhead support includes a central axial passage¬ way 70 which houses the front portion 72 of a conveyor assembly and a hopper or collector 74 associated therewith. The cutterhead sup¬ port also supports a large diameter bearing 76 of a type which is commonly used in tunneling machines having open centered cutter- heads. The box beam 6θ is secured to a second smaller diameter box beam 78 which is directly supported for rotation by the bearing 76. The mounting ring 66 is secured to a front radial wall 80 of box beam 78. The usual dirt seals 82, 84 are provided between the rotating and non-rotating parts at each end of the bearing 76. As best shown by FIGS. 1 and 7 - 10 the center cutter assembly 28 is mounted inside of the center hub structure 32. The center cutter assembly 28 comprises four disc cutters 86. Mounting frames are used which permit mounting of the center cutter assem 28 from the rear side of the cutterhead. Center cutter assembly 28 may include two parts, each including a pair of disc cutters 86 mounted on a single shaft 87. When the center cutter assembl 28 is inserted into the open center of hub structure 32, support portions 88 enter spaces between retainer portions 90 of the hub structure 32. These retainer portions 90 border the sides of th window 47. The center cutter mounting frames also includes moun ing flanges 92, formed to include openings 94 (FIG. 9) for recei bolts 96 which thread into threaded openings 98 which are formed in retainer portions 9°. Referring now to FIGS. 11 - 13, the single disc cutte units 26 which are mounted within the radial beams 48 are mounte by a cutter mount structure which also functions as a lateral re inforcement for the beams 48. This structure may comprise a box which includes a pair of radially spaced apart end walls 100, 10 The end walls 100, 102 are welded into place between the beam si walls 50, 5 to form cutter compartments or wells. The inner fa of each end member 100, 102 is constructed to include an avenue 108, 110 sized to receive an end portion 104, 106 of the stator of the cutter assembly 26, and also load transfer blocks 112, 11 The roller cutter assembly 26 is moved into and is re moved out from the cutter well from behind the cutterhead 20. F 13 shows a roller cutter assembly 26 spaced rearwardly from the portal of its cutter well. When assembly 26 is moved forwardly the well the end portions 104, 106 enter via the avenues 108, 11 The roller cutter assembly 26 is moved forwardly until the front of the end members 104, 106 are against forward stops 111. Then, transferring blocks 112, 114 are moved through the rear portal a to the channels 108, 110 (FIG. 12). Bolts ll6 may be inserted t openings 118 formed through the blocks 112, 114 and threaded int openings 120 provided in the frame members 100, 102. As will be preciated, when the bolts ll6 are tightened they will draw the l transfer blocks 112, 114 into tight engagement with load carryin surfaces which are the forwardly directed vertical surfaces of channels 108, 110. Such load carrying surfaces constitute surfaces on th cutterhead frame since the end members 100, 102 are integral por of the cutterhead frame. Thus thrust loads imposed on the cutti portion of the roller cutter are transmitted in compression through the load transfer blocks 112, 114 into the cutterhead frame. Referring to FIG. 2, the cutterhead may be completed by adding auxiliary frame members 126 (plates on edge) in a spaced relationship to the frame members 50, 52 to define spaces along¬ side of the inner spaces of the spokes which are very similar to the inner spaces of the spokes for receiving additional roller cutters. The cutterhead may also be provided with radially elon¬ gated scoops 128 and a plate metal facing around the scoops and in between the radial beams 48. As shown by FIG. 2, . the scoops have inlets for the mined material which commence adjacent the hub 32 and extend out to the periphery of the cutterhead. During tunneling the collector 74 at the forward end of the conveyor 72 is positioned relatively close behind the center cutter assembly 28. The cuttings picked up by the scoops 128 drop into the collector 74. They fall onto the conveyor belt 130 and are carried thereby to a system of additional conveyors and/or material carts which remove the mined material out from the tunnel in one of a number of known ways. Provision is made for retracting the collector so that access may be had to the inner space IS of the cutterhead, for the purpose of replacing cutters. One way of moving the conveyor out of the way would be to construct the conveyor so that it could be retracted in total from its operative position. The rear end of the conveyor is mounted on wheels or the like, and the front end of the conveyor is normally connected to the cutterhead support 10. In preparation to replace a cutter the front end of the conveyor could be disconnected from the cutterhead support, and then the conveyor could be forced rearwardly. The cutterhead support could be provided with some sort of bearing arrangement to support the front end portion of the conveyor for sliding movement. However, it is presently contemplated that the forward frame portion of the cutterhead, which includes the material collector 7 and a forward pulley 132 on which the conveyor belt reverses its direction, are mounted to be movable relative to both the cutterhead support 10 and the rest of the conveyor. As shown by FIGS. 14 and 15, a pair tracks 1 , 136 may be provided to extend axially of the tunnel on opposite sides of the conveyor 72. A front end carriage 138 may be mounted for axial movement in the tunnel by means of rollers 140 OMPI which are engaged by the tracks 134, 136. The front end portion the conveyor frame, including the material collector 74 and the front roller 132 are carried by the carriage 138. The carriage 138 may be controlled in position by means of one or more hydrau cylinders 142 (FIG. 14) which extend axially of the tunnel and are connected at their forward ends to the carriage 138 and at their rearward ends to a portion of the cutterhead support 10. The cylinders 142 are extended for the purpose of moving the col lector into the material collecting position relative to the cut head. When in this position, the conveyor belt 130 is tightened The cylinders 142 may be retracted for the purpose of moving the front portion of the conveyor rearwardly an amount sufficient to create sufficient working room within the inner space IS of the cutterhead (FIG. 14). Retraction of the. cylinders 142 causes th to move the forward frame portion of the conveyor belt rearwardl relative to both the cutterhead and the conveyor belt. The thus slackened forward end portion of the conveyor belt is then merel folded out of the way, so that it will not interfere with the cu ter removal and installation work within the inner space IS. Of course, the manner of moving the forward end portion of the con¬ veyor 72 out from the inner space IS could be accomplished in an one of a number of other ways, as well.

Claims: CLAIMS 1. A main frame for a rotary cutterhead of an earth boring machine, said main frame comprising an annular beam by which the cutterhead is mounted onto an earth boring machine, for rotation about an axis of rotation; a box-like hub structure comprising peripheral wall means defining a center space; a pluralit of radial spoke beams having inner ends which are integrally con¬ nected to the peripheral wall means of the hub structure and outer ends which are integrally connected to the annular beam, each said radial spoke beam comprising a pair of spaced apart side plate mem¬ bers and wherein each radial spoke beam extends rearwardly of the hub structure as it extends radially outwardly from the hub struc¬ ture to the annular beam. 2. A main frame according to claim 1, wherein each radial spoke beam extends rearwardly as it extends radially out¬ wardly from the hub structure to the annular box beam. 3. A main frame according to claim 1 or 2, wherein the peripheral wall means of the hub structure comprises six walls interconnected to give the hub structure a generally hexahedral form and wherein the main frame comprises six radial spoke beams, with the inner ends of the radial spoke beams being connected to the hub structure generally at the corner regions where the walls of the hub structure meet each other. 4. A rotary cutterhead for an earth boring machine comprising a main frame including an annular beam by which the cutterhead is mounted onto an earth boring machine, for rotation about an axis of rotation; a box-like hub structure comprising peripheral wall means defining a center space a plurality of radial spoke beams having inner ends which are integrally con¬ nected to the peripheral wall means of the hub structure and outer ends which are integrally connected to the annular box beam, each said radial spoke beams comprising a pair of spaced apart side plate members; roller cuttermounts within said radial spoke beams comprising wall members which extend transversely of the radial spoke means and are integrally connected at their ends to the spaced apart side plate members, to also function as structural brace members for the radial spoke beams; wherein the cutter mounts are adapted for installation and removal of roller cutter from the rear side of the cutterhead, and wherein said main fram is configured to provide an interior space for. a workman which i large enough to provide room for installation and removal of rol ler cutters from behind the cutterhead. 5. A rotary cutterhead according to claim 4, includi roller gauge cutters generally at the periphery of the cutterhea and wherein in the regions of the gauge cutters the side plate members of the radial- spoke beams curve rearwardly generally ove the interior space, and wherein such regions the means mounting the gauge cutters between the side plate members defines install and removal paths which extend generally vertically in regions f wardly of the annular box beam. 6. A rotary cutterhead according to claim 4 or , wherein each radial spoke beam extends rearwardly as it extends radially outwardly from the hub structure to the annular box beam. 7. A rotary cutterhead according to claim 4, 5 or 6 wherein the peripheral wall means of the hub structure comprises six walls interconnected to give the hub structure a generally hexahedral form, and wherein the main frame comprises six radial spoke beams, with the inner ends of the radial spoke beams being connected to the hub structure, generally at the corner regions where the walls of the hub structure meet each other. 8. A rotary cutterhead according to any of claims 4 7, including a center cutter assembly comprising a plurality of ler cutters and means mounting said roller cutters within the ce space of the hub structure, with peripheral portions thereof pro jecting forwardly from the cutterhead main frame. 9- An earth boring machine comprising a cutterhead support including a relatively large central passageway; bearing means on said cutterhead support surrounding said passageway; a rotary cutterhead comprising an annular box beam by which the cu terhead is mounted onto said bearing, for rotation about an axis of rotation; a box-like hub structure comprising peripheral wall means defining a center space; and a plurality of radial spoke b having inner ends which are integrally connected to the peripher wall means of the hub structure and outer ends which are integrally connected to the annular box beam, each said radial spoke beam comprising a pair of spaced apart side plate members defining spaces between them; a center cutter assembly comprising a plur¬ ality of roller cutters and center cutter mount means for de- tachably mounting said roller cutters within the center space of the hub structure, with peripheral portions thereof projecting forwardly from the cutterhead main frame, and providing for in¬ stallation and removal of the roller cutters from behind the cut¬ terhead; and wherein spaces exist between the spoke beams through which mined material may pass axially through the cutterhead; a plurality of roller cutters spaced radially outwardly of said center cutter assembly and cutter mount means for detachably mounting them within the spaces between the side plate members, with per¬ ipheral portions thereof projecting forwardly from the cutterhead main frame, and providing for installation and removal of the rol¬ ler cutters from behind the cutterhead; and mined material receiving collector means supported within said passageway, for movement be¬ tween a forward position in which it is located partially within the inner space of the cutterhead, in a position to receive the mined material, and a retracted rearward position in which it is spaced far enough rearwardly from the center cutter assembly to provide sufficient room for installation and removal of the center cutter assembly to provide sufficient room for installation and removal of the center cutter assembly into and out from the center space of the box-like hub structure. 10. An earth boring machine according to claim 9, comprising roller gauge cutters generally at the periphery of the cutterhead, and wherein in the regions of the gauge cutters the side plate members of the radial spoke beams curve rearwardly generally over the interior space, and wherein such regions the means mounting the gauge cutters between the side plate members defines installation and removal paths which extend generally vertically in regions forwardly of the annular box beam. AMENDED CLAIMS (received by the International Bureau on 28 May 1980 (28.05.80)) 1. A main frame for a rotary cutterhead of an earth boring machine, said main frame comprising an annular beam by which the cutterhead is mounted onto an earth boring machine, for rotation about an axis of rotation; a box-like hub structure comprising peripheral wall means defining a center space; a plu of radial spoke beams having inner ends which are integrally co nected to the peripheral wall means of the hub structure and ou ends which are integrally connected to the annular beam, each s radial spoke beam comprising a pair of spaced apart side plate bers and wherein each radial spoke beam extends rearwardly of t hub structure as it extends radially outwardly from the hub str ture to the annular beam. 2. A main frame according to claim 1, wherein each radial spoke beam extends rearwardly as it extends radially out wardly from the hub structure to the annular box beam. 3. A main frame according to claim 1 or 2, wherein the peripheral wall means of the hub structure comprises six wa interconnected to give the hub structure a generally hexahedral and wherein the main frame comprises six radial spoke beams, wit the inner ends of the radial spoke beams being connected to the structure generally at the corner regions where the walls of the hub structure meet each other. 4. A rotary cutterhead for an earth boring machine comprising a main frame including an annular beam by which the cutterhead is mounted onto an earth boring machine, for rotatio about an axis of rotation; a box-like hub structure comprising peripheral wall means defining a center space; a plurality of radial spoke beams having inner ends which are integrally con¬ nected to the peripheral wall means of the hub structure and out ends which are integrally connected to the annular box beam, eac said radial spoke beams comprising a pair of spaced apart side plate members; roller cuttermounts within said radial spoke beam comprising wall members which extend transversely of the radial spoke means and are integrally connected at their ends to the spaced apart side plate members, to also function as structural OMP brace members for the radial spoke beams; wherein the cutter mounts are adapted for installation and removal of roller cutters from the rear side of the cutterhead, and wherein said main frame is configured to provide an interior space for a workman which is large enough to provide room for installation and removal of rol¬ ler cutters from behind the cutterhead. 5, A rotary cutterhead according to claim 4, including roller gauge cutters generally at the periphery of the cutterhead, and wherein in the regions of the gauge cutters the side plate members of the radial spoke beams curve rearwardly generally over the interior space, and wherein such regions the means mounting the gauge cutters between the side plate members defines installation and removal paths which extend generally vertically in regions for¬ wardly of the annular box beam. β. A rotary cutterhead according to claim 4 or 5. wherein each radial spoke beam extends rearwardly as it extends radially outwardly from the. hub structure to the annular box beam. (amended) 7. A rotary cutterhead according to claim 4 or 5 wherein the peripheral wall means of the hub structure comprises six walls interconnected to give the hub structure a generally hexahedral form, and wherein the main frame comprises six radial spoke beams, with the inner ends of the radial spoke beams being connected to the hub structure generally at the corner regions where the walls of the hub structure meet each other. ( am e n d e d) 8. A rotary cutterhead according to claim 4 or 5, including a center cutter assembly comprising a plurality of rol¬ ler cutters and means mounting said roller cutters within the center space of the hub structure, with peripheral portions thereof pro¬ jecting forwardly from the cutterhead main frame. 9. An earth boring machine comprising a cutterhead support including a relatively large central passageway; bearing means on said cutterhead support surrounding said passageway; a rotary cutterhead comprising an annular box beam by which the cut¬ terhead is mounted onto said bearing, for rotation about an axis of rotation; a box-like hub structure comprising peripheral wall means defining a center space; and a plurality of radial spoke beams having inner ends which are integrally connected to the peripheral wall means of the hub structure and outer ends which are integra connected to the annular box beam, each said radial spoke beam comprising a pair of spaced apart side plate members defining spaces between them; a center cutter assembly comprising a plur¬ ality of roller cutters and center cutter mount means for de- tachably mounting said roller cutters within the center space of the hub structure, with peripheral portions thereof projecting forwardly from the cutterhead main frame, and providing for in¬ stallation and removal of the roller cutters from behind the cut terhead; and wherein spaces exist between the spoke beams throug which mined material may pass axially through the cutterhead: a plurality of roller cutters spaced radially outwardly of said ce cutter assembly and cutter mount means for detachably mounting them within the spaces between the side plate members, with per¬ ipheral portions thereof projecting forwardly from the cutterhea main frame, and providing for installation and removal of the ro ler cutters from behind the cutterhead; and mined material recei collector means supported within said passageway, for movement b tween a forward position in which it is located partially within inner space of the cutterhead, in a position to receive the mine material, and a retracted rearward position in which it is space far enough rearwardly from the center cutter assembly to provide sufficient room for installation and removal of the center cutte assembly to provide sufficient room for installation and removal of the center cutter assembly into and out from the center space of the box-like hub structure. 10. An earth boring machine according to claim 9, comprising roller gauge cutters generally at the periphery of the cutterhead, and wherein in the regions of the gauge cutters the side plate members of the radial spoke beams curve rearwardl generally over the interior space, and wherein such regions the means mounting the gauge cutters between the side plate members defines installation and removal paths which extend generally vertically in regions forwardly of the annular box beam. _O PI v/ WIPO

Inventors: SPENCER B
Applicants: ROBBINS CO
Application year: 1979
Main classification: E21C27
IPC codes: E21B10, E21D9