Patent Publication Number: US-9845677-B2

Title: Cutter assembly with inline mounting

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a claims the benefit of Provisional Application No. 62/247,714 filed Oct. 28, 2015, the disclosure of which is hereby incorporated by reference herein. 
    
    
     BACKGROUND 
     A tunnel boring machine (“TBM”) is a tunnel excavation apparatus for forming tunnels in a variety of soil and rock strata. A conventional TBM produces a smooth circular tunnel wall, with minimal collateral disturbance. As discussed in U.S. Pat. No. 8,172,334, to Lindbergh et al, which is hereby incorporated by reference in its entirety, a conventional TBM typically includes a full face rotatably driven cutterhead that supports a plurality of cutter assemblies. Typically, a cutterhead may have 20, 50, 100, or more cutter assemblies rotatably mounted to the cutterhead. 
     A breakthrough that made TBMs efficient and reliable was the invention of the rotating head, developed by James S. Robbins. Initially, Robbins&#39; TBM used rigid spikes rotating in a circular motion, but the spikes would frequently break. He discovered that by replacing these grinding spikes with longer lasting rotatable cutter assemblies this problem was significantly reduced. Since then, modern TBMs include rotatable cutter assemblies. 
     In operation, the cutter head is urged against a surface to be bored such that at least some of the cutter assemblies forcibly engage the surface. In some TBMs a plurality of opposing sets of hydraulic cylinders engage the tunnel walls to anchor the TBM, and separate thrust cylinders press the rotating cutterhead against the rock or ground surface. The cutterhead rotates about a longitudinal axis so that as the cutter assemblies are forcibly pressed against the surface they roll along the surface to fracture, loosen, grind, dislodge, and/or break materials from the surface. 
     As illustrated in Lindbergh et al., rotatable cutter assemblies are mounted in housings in the TBM cutterhead assembly such that the cutter ring extends forward from the face of the cutterhead assembly to engage the earthen rock wall. During operation of a TBM the cutterhead assembly is pressed with great force against the rock face, typically with hydraulic actuators, while the cutterhead is rotated about its axis. The outer cutter ring of the cutter assemblies produce local stresses that cause the surface of the wall to fracture and crumble. The fractured and loosened material is collected and removed to gradually form the tunnel. 
     Another illustrative tunnel boring machine is disclosed in U.S. Pat. No. 4,548,443, to Turner, which is hereby incorporated by reference. A main frame for a TBM is disclosed in U.S. Pat. No. RE 31511, to Spencer, which is hereby incorporated by reference in its entirety. A TBM with continuous forward propulsion is disclosed in U.S. Pat. No. 5,205,613, to Brown, which is hereby incorporated by reference. The TBM and a cutter disc assembly and sensor apparatus for a TBM disclosed in U.S. Pat. No. 8,172,334, to Lindbergh et al., provides a means for wireless monitoring the operation of the cutter assemblies. 
     The cutterhead assembly and the cutter assemblies are subjected to very high forces during tunnel boring operations. Once excavation of the tunnel is started, it is very difficult to repair or replace the cutter assemblies because the assemblies are difficult to access in situ, and the cutter assemblies are heavy, often weighing many hundreds of pounds. Tunnels are often at significant depths, with correspondingly high ambient pressures. Therefore, it is critical that the installation of the cutter assembly in the cutterhead be very secure and reliable, even under the extreme conditions associated with tunnel boring. 
       FIG. 1  herein shows an exploded view of a conventional cutter assembly housing for a tunnel boring machine, from Lindbergh et al. The cutter assembly  10 , comprising a cutter ring  15  disposed on a hub  12  that is mounted for rotation about a shaft  13 . Bearing assemblies (not shown) are mounted generally on the shaft  13  to provide for rotation of the hub  12  and cutter ring  15  about the shaft  13 . 
     The conventional cutter housing shown in  FIG. 1  comprises spaced-apart housing mounts  20 L,  20 R (sometimes referred to as mounting plates). Opposite ends of the shaft  13  are secured in the housing mounts  20 L,  20 R in L-shaped channels  21  (one visible) that are sized to receive the cutter assembly shaft  13 . Typically the cutter assembly  10  is installed by positioning the opposite ends of the shaft  13  at the back of the housing mounts  20 L,  20 R to engage the long leg of the L-shaped channels  21 . The cutter assembly  10  is slid along the long leg of the L-shaped channel  21  and then shifted laterally into the recess formed by the shorter leg of the L-shaped channels  21 . The cutter housing secures the cutter assembly  10  to the housing mounts  20 L,  20 R with a pair of wedge-lock assemblies that engage respective ends of the shaft  13 . 
     The wedge-lock assemblies each include a wedge  22 , a clamp block  24 , and an optional tubular sleeve  28  disposed therebetween. The wedge  22  is positioned to abut an angled face on the end of the shaft  13 , and the clamp block  24  engages abutment surfaces  25  on the back end of the associated housing mount  20 L,  20 R. A bolt  23  extends through the wedge  22 , the sleeve  28 , and the clamp block  24 , and is secured with two nuts  26  and a washer  27 . As the bolt  23  is tensioned by torqueing the nuts  26  to a design specification, the wedge  22  locks the cutter assembly  10  in place. 
     In practice, this mounting has presented certain challenges and disadvantages. For example, the “wedge drop-down” (the cutter assembly  10  lateral shift into the shorter leg of the L-shaped channel  21 ) required to fit the wedge  22  into place requires space on the TBM cutterhead assembly can be challenging. In a typical installation the cutter assembly  10  drops about 4 inches into the housing pocket of channel  21  to enable installation of the wedge  22  to lock the cutter assembly  10  into positions via the bolt  23  that spans length of the housing mounts  20 R,  20 L. 
     In addition, the shallow angle on the wedge  22  is typically relied on to press the cutter assembly  10  laterally into the desired position in the channel  21 . The more shallow the wedge angle or lower friction coefficient on the wedge  22 , the more effective it is at holding the cutter assembly  10  in position via the mechanical advantage of the wedge  22 . 
     The lateral shift makes it difficult to ensure that the cutter assembly shaft is securely supported in the housing. It will be appreciated by persons of skill in the art that if the shaft is not securely seated in the housing, for example, if any motion between the shaft and the housing develops, the high dynamic forces associated with the tunnel boring process will lead to rapid failure of the assembly. Situating the shaft in the lateral segment of the L-shaped channel makes it very difficult to detect if the shaft is properly seated, and does not provide for an effective mechanism for seating the shaft against both walls in the shifted portion of the channel. 
     Another disadvantage of this conventional design, that can be particularly prevalent when doing in-field maintenance, is that if dirt or other debris is unintentionally present in the L-shaped channel  21  when the wedge  22  is tightened to secure the cutter assembly  10 , and the debris becomes dislodged during operation, the cutter assembly  10  may no longer be suitably secured, which can lead to serious damage to the cutter assembly  10  (and potentially the cutterhead), more rapid wear of the cutterhead  10 , and more frequent maintenance requirements. 
     Also, removal of the cutter assembly  10  from the housing  20 L,  20 R is challenging, particularly for repair or replacement in the field, because the (heavy) cutter assembly  10  must usually be shifted laterally in the L-shaped channel  21  to align it with the long leg of the channel  21  prior to pulling the cutter assembly out. 
     There remains a need for improved and more reliable systems for mounting cutter assemblies to the cutterhead in tunnel boring machines. 
     SUMMARY 
     This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     An inline mounting assembly for mounting a cutter disc assembly onto a tunnel boring machine (TBM) includes similar first and second mounting subassemblies. The first mounting subassembly includes a housing mount with a body portion and a front end with inwardly extending first and second ears, and a channel extending from a back end to the front end. First and second guides are provided on either side of the channel to define front and back abutment surfaces. A wedge assembly includes an elongate member, for example a bolt, that extends through an aperture in the first guide, and a wedge that engages a distal end of the elongate member. A back support assembly includes a second elongate member that extends through a clamp block that abuts the back abutment surface and engages a bridge block that abuts the front abutment surface. A front end of the bridge block is configured to abut a shaft of the cutter disc assembly, and the wedge is configured to slideably engage the first ear of the housing mount and the shaft, such that the shaft is clamped between the wedge and the second ear of the housing mount. 
     In an embodiment the second mounting subassembly is substantially identical to the first mounting subassembly in mirror image. 
     In an embodiment the first elongate member is a bolt that threadably engages the wedge and is configured to apply an adjustable force on the wedge. 
     In an embodiment the first guide is a substantially uniform rectangular protrusion from the body of the housing mount. 
     In an embodiment a back end of the first and second guides define recesses configured to receive the clamp block. 
     In an embodiment the bridge block comprises a relatively wide back face that abuts the front abutment surface and a relatively narrow front face that is configured to abut the shaft. 
     In an embodiment the second elongate attachment member comprises a bolt that is configured to engage the shaft of the cutter disc assembly. 
     In an embodiment the housing mount is formed as a single-piece unitary mount. 
     In an embodiment the first guide or the second guide, or both, are removably attached to the body portion of the housing mount. 
     In an embodiment the second elongate member is configured to preload the shaft of the cutter assembly against the bridge block. 
     A cutter assembly and inline mount for a tunnel boring machine includes a cutter assembly having a shaft and a cutter ring or disc disposed on a hub that is rotatably mounted to the shaft. An inline mounting assembly has first and second mounting subassemblies. The mounting subassemblies include (i) a mounting plate having a body portion and a front end with inwardly extending first and second shaft supporting portions, the mounting plate having a channel extending from a back end of the mounting plate to the front end and sized to receive an end of the shaft, a first guide disposed on one side of the channel, and a second guide disposed on the other side of the channel, wherein the first guide and the second guide cooperatively define a back abutment surface and a front abutment surface; (ii) a wedge assembly comprising a first elongate attachment member that extends through an aperture in the first guide and a wedge that engages a distal end of the first elongate attachment member; (iii) a back support assembly comprising a clamp block that abuts the back abutment surface, a bridge block that abuts the front abutment surface, and a second elongate attachment member that extends through an aperture in the clamp block and an aperture in the bridge block. A front end of the bridge block is configured to abut the shaft. The wedge is configured to slideably engage the first inwardly extending shaft supporting portion, and to slideably engage the shaft such that the shaft is clamped between the wedge and the second inwardly extending shaft supporting portion of the mounting plate. 
     In an embedment the second mounting subassembly is substantially identical to the first mounting subassembly in mirror image. 
     In an embodiment the first elongate member has a first bolt that engages the wedge and is configured to apply an adjustable rearward force on the wedge. 
     In an embodiment the first guide is formed as a substantially uniform rectangular protrusion. 
     In an embodiment a back end of the first guide defines a first recess and a back end of the second guide defines a second recess, and the recesses cooperatively receive the clamp block. 
     In an embodiment the bridge block is shaped as an isosceles trapezoid with a relatively narrow front face that is configured to abut the shaft. 
     In an embodiment the second elongate attachment member comprises a bolt that threadably engages the shaft of the cutter disc assembly. 
     In an embodiment the mounting plate is formed as a single-piece unitary mount. 
     In an embodiment the first guide and the second guide are removably attached to the body portion of the mounting plate. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a perspective, partially exploded view of a prior art cutter assembly and mounting system; 
         FIG. 2  is a perspective view of a cutter assembly mounted in a cutter attachment and housing assembly, in accordance with the present invention; 
         FIG. 3  is a perspective view of the left housing mount shown in  FIG. 2 , with the wedge assembly installed, wherein the right housing mount and related components are omitted for clarity; 
         FIG. 4  is a perspective view of the left housing mount shown in  FIG. 2 , with the cutter assembly shaft inserted, wherein the body of the cutter assembly is omitted for clarity; 
         FIG. 5  is a perspective view of the left housing mount shown in  FIG. 2 , with the back support assembly also shown installed; and 
         FIG. 6  is a partially exploded view illustrating insertion of the cutter ring assembly into the housing assembly shown in  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     A TBM cutter attachment and housing assembly in accordance with the present invention overcomes the disadvantages described above. An exemplary embodiment of the cutter attachment and housing assembly  100  is shown in a right-rear perspective view in  FIG. 2 , with a cutter assembly  115  installed. In this embodiment, a pair of housing mounts  120 , which are configured to be attached to the main cutterhead assembly (not shown), are each provided with a wedge assembly  130  and a back support assembly  140 . The wedge assembly  130  and back support assembly  140  cooperate to secure the cutter assembly  115  in the housing  120  such that the cutter assembly  115  is rotatable on a shaft  117  (see  FIG. 3 ), with a portion of the cutter assembly  115  extending forwardly from the housing  120 . Importantly, the shaft  117  is inserted along a straight-line channel  123  without requiring any shift away from the channel, and is supported inline. 
       FIG. 3  shows the left housing mount  120  with the wedge assembly  130  installed to the mount  120 . In order to show other aspects of the assembly, the right housing mount  120  and other components are not shown. Refer also to  FIG. 6 , which shows an exploded view of one side of the housing assembly  100 . 
     In a current embodiment the right housing mount  120  is substantially similar in mirror symmetry to the left housing mount  120 . In some embodiments there may be advantages or reasons for various differences between the left and right housing mounts and related components, for example, to accommodate mounting on a particular cutterwheel design or to simplify the assembly. The housing mount  120  includes upper and lower protrusions or ears  121  that extend inwardly from the body of the housing mount  120 . The ears  121  reduce the exposed cutter opening, serve to spread the wedge and cutter tangential loads to the cutterhead structure, and provide surfaces for reacting clamping forces supporting and securing the cutter assembly shaft  117 . 
     The housing mount  120  includes a bolt guide  122  as shown in  FIG. 3  having a through-hole  137  configured to slideably receive an attachment member, for example, a bolt  131  for the wedge assembly  130 . The bolt  131  extends through the through-hole  137  in the bolt guide  122  and engages a wedge  132 . For example, the wedge  132  may be threadably attached to the bolt  131 . An upper face  133  of the wedge  132  is configured to slideably engage a lower face of the associated ear  121  of the housing mount  120 . An angled lower face  134  is configured to slideably engage a corresponding face of the shaft  117  end ( FIG. 6 ). 
       FIG. 4  shows the subassembly of  FIG. 3 , with the cutter assembly shaft  117  positioned to engage the wedge  132 . It will be appreciated that as the bolt  132  is tightened the wedge is pulled rearwardly by the bolt  132 . Therefore, the cutter assembly shaft  117  is clampingly engaged between the wedge  132  and the lower ear portion  121  of the housing  120  to secure the cutter assembly  115  in the housing. The wedge  132 , which engages a face on the shaft  117 , is angled such that tightening the bolt  132  also causes the wedge  132  to also apply a rearward force on the shaft  117  end. The opposite end of the shaft  117  is similarly clamped by the other housing mount  120 . 
     The housing mount  120  in this embodiment further defines a channel  123  that extends along the length of the housing mount  120 . The channel  123  is sized to receive an end of the cutter assembly shaft  117 . The left and right housing mounts  120  will therefore receive opposite ends of the shaft  117 , allowing the cutter assembly to be positioned in the mount by sliding the cutter assembly from the back end of the mounts  120  to the front end. The corresponding wedges  132  may be prepositioned to prevent the cutter assembly  115  from traveling too far along the channel  123 . 
     Referring still to  FIGS. 3 and 4 , the housing mounts  120  (one shown) further include a second guide or abutment member  124  that is generally parallel to, and spaced apart from, the bolt guide  122 . The second guide  124  is located on the opposite side of the channel  123  as the bolt guide  122 . The bolt guide  122  and the second guide  124  each include corresponding recesses  125  at the back end of the housing mount  120 . The recesses  125  are sized and positioned to cooperatively receive and abut a clamp block  142  as shown in  FIG. 5 , and discussed below. 
     The bolt guide  122  and the second guide  124  extend only part way towards a front end of the housing mount  120 , thereby cooperatively defining a gap  126 , for the back support assembly  140 . 
       FIG. 5  is similar to  FIG. 4 , with the back support assembly  140  also installed in the housing mount  120 . Refer also to the exploded view in  FIG. 6 . The back support assembly  140  includes an attachment member, for example, a bolt  141  that extends through the clamp block  142  and to or through a bridge block  143 . In this embodiment the bolt  141  threadably engages the cutter assembly shaft  117  through the threaded aperture  118 . Other attachment mechanisms may alternatively be used. In an alternative embodiment the bolt  141  is configured to attach directly to the bridge block  143 , and the bridge block  143  abuts the shaft  117 . The clamp block  142  is sized to engage and abut the recesses  125  in the bolt guide  122  and the second guide  124 , as discussed above. 
     The bridge block  143  abuts forward ends of the bolt guide  122  and the second guide  124 . The bridge block  143  may be suitably positioned by sliding the bridge block  143  through the gap  126  between the second guide  124  and the lower ear portion  121  (e.g., moving upwardly in  FIG. 6 ), before inserting the bolt  141 . The bridge block  143  therefore bridges the ends of the bolt guide  122  and the second guide  124  nearest the shaft  117 . 
     Tightening the bolt  141  to a design torque securely seats the cutter assembly shaft  117  against the bridge block  143 . The wedge assembly bolt  131  is tightened to secure the cutter assembly  115  in the housing mounts  120 . The wedge assembly  130  securely clamps the shaft  117  between the wedge  132  and the upper face of the lower ear portion  121  of the housing mount  120 . 
     In contrast to prior art cutter assembly mounting assemblies, the cutter assembly  115  is mounted inline, slideably inserting the ends of the cutter assembly shaft  117  into the opposed channels  123  of the housing mounts  120 , and sliding the cutter assembly  115  forward, without requiring the “wedge drop-down” or lateral shift discussed above. Thus the wedge  132  may be optimized for providing the maintaining lateral clamping of the cutter assembly  115  via the mechanical advantage provided by the wedge. 
     The disclosed system  100  simplifies mounting and removing cutter assemblies  115  from the cutterhead. 
     For example, in some instances to install the cutter assembly  115  the left and right wedge assemblies  130  are installed and the cutter assembly  115  is then positioned to slideably engage the opposed channels  123  from the back and slide forward until the shaft  117  ends engage the wedges  132 . For each housing mount  120  the clamp block  142  is positioned in the recesses  125 , the bridge block  143  is inserted through the gap  126  between the shaft  117  and the bolt guide  122  second guide  124 , and the second bolt  141  is inserted through both blocks  142 ,  143  and threadably engages the corresponding aperture  118  in the shaft  117 . In embodiments wherein the second bolt  141  threadably engages the shaft  117 , tightening the second bolt  141  preloads the shaft  117  securely against the bridge block  143 . 
     Tightening the second bolt to a first design torque secures the shaft  117  to the bridge block  143 , and tightening the bolt  131  secures the shaft  117  laterally in the housing mount  120 . In some cases the cutter assembly  117  may alternatively be positioned in the channels  123  from the front end of the housing mounts  120 , prior to installing the wedge assemblies  130 , and the wedge assembly  130  and back support assembly  140  installed in situ. 
     Removal of the cutter assembly  117 , for example, for replacement or maintenance in the field, is simplified because the cutter assembly  115  does not have to be shifted laterally to be in a position for removal. After removal of the back support assembly  140  and loosening the wedge assembly  130 , the cutter assembly  115  may be simply pulled rearwardly along the channels  123 . 
     In the disclosed inline loading system, the cutter assembly  115  slides directly into the mounted position. The bridge block  143  is located directly behind the cutter assembly shaft  117 , which is clamped initially against the bridge block  143  to fully position the cutter assembly  115 . The wedge  132  is then drawn into position to lock the cutter assembly  115  in place. In prior art systems the position of the cutter in the housing is not established prior to the wedge being engaged, and the cutter assembly change personnel cannot see if the housing seats are cleaned properly or even see if the cutter is positioned properly. 
     The housing assemblies such as the housing assembly  100  of  FIG. 2  may also be smaller than conventional housing systems (for example, the prior art system shown in  FIG. 1 ) because the housing mounts use an inline mounting channel, and do not require prior art L-shaped channels  21 . 
     Although the bolt guide  122  and the abutment guide  124  in the current embodiment are generally rectangular and unitary protrusions from the body portion of the housing mount  120 , it is contemplated that these members may be formed as multiple short protrusions. For example, the bolt guide  122  may be formed as two or more aligned lugs, for example, a first lug located at or near a back end of the housing mount  120  and providing an abutment for the clamp block  142 , and a second lug located at or near the front end of the bolt guide  122  shown in  FIG. 3 , providing an abutment for the bridge block  143 . 
     Although in the currently current embodiment shown in  FIG. 2  each of the housing mounts  120  are formed as an unitary construction, it is contemplated that the housing mounts  120  may alternatively be formed as an assembly or modularly, to improve maintainability of the assembly  100 , and/or to improve manufacturability. In particular, in another embodiment the first and second guides  122 ,  124  may be formed as separable portions of the housing mount  120 . The guides  122 ,  124  experience higher cyclical loadings than other portions of the housing mount  120 , and therefore may be more susceptible to damage. It is contemplated that the first guide  122  and/or the second guide  124  may be formed separately, and assembled to the back portion to form the housing mount  120 , for example with bolts or other attachment means as are known in the art. In an exemplary embodiment the back plate portion of the housing mount  120  includes recesses for slideably receiving and securing such modular guides  122 ,  124 . An assembled housing mount  120  would facilitate repair and/or maintenance of the assembly  100 , allowing users to replace the guides  122 ,  124  if they become worn or damaged without removing the entire mount  120  from the cutterwheel. Separable guides  122 ,  124  would also allow the guides  122 ,  124  to be formed from a different material than the rest of the housing mount  120 . Separable guides  122 ,  124  would also allow the assembly  100  to be customized or modified, for example to accommodate different cutter assemblies  115 . 
     While illustrative embodiments have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.