Abstract:
A method of forming a cutter head with an axis of rotation comprises forming a hub; forming at least one ring with integral cutter body arm segments extending from the at least one ring; and connecting the hub to the cutter body arm segments so that the hub and the at least one ring are connected and around the axis of rotation.

Description:
BACKGROUND 
       [0001]    Cutter-suction dredgers (“CSD”) are vessels which can be used to cut and loosen material which is at least partly underwater. This cut material can then be sucked into a suction tube. CSD&#39;s are often used to cut hard surface materials, such as rock, although they may also be used to excavate gravel or sand. 
         [0002]    CSD&#39;s typically use a suction tube with a cutter head at the suction inlet. The cutter head may be connected to the dredger with a hub that is mounted on an axis with a drive to rotate the cutter head. The axis of rotation is referred to as the axial direction of the cutter head. The cutter head and suction inlet may be moveable with respect to the water bed being dredged. In order to draw the material into the suction tube, a wear-resistant pump may be provided, for example, a centrifugal pump. The material cut by the cutter head that has been drawn into the suction tube may then be transported away from the CSD, for example, by a floating pipe line to a dumping location. 
         [0003]    A typical cutter head includes a base ring around the suction opening and a hub. The hub and base ring are connected by a plurality of arms extending in an axial direction. The arms may be curved in a tangential and radial direction such that the arms spiral toward each other. In other cutter heads, the arms may be curved in the radial direction only, while being axially aligned or at a small angle with respect to the axial direction. Each arm must be connected to the base ring and to the hub, typically by welding. 
         [0004]    The cutter head may additionally be provided with different excavating tools, for example, teeth in the shape of chisels or another shape to assist in the excavation. The teeth can be attached to the arms. 
         [0005]    WO2011003869 discloses an example of a cutter head for dredging ground under water. This cutter head is suitable for attachment rotatably around a central axis to a cutter suction dredger and can be moved through the ground therewith in a lateral sweeping movement. The cutter head is formed from support arms which extend spirally between a base ring and a hub located at a distance from the base ring. The support arms are connected to the base ring and to the hub. 
       SUMMARY 
       [0006]    The present invention is directed toward a method of forming a cutter head with an axis of rotation with at least one ring with integral cutter body segments extending from the at least one ring. The method can comprise forming a hub; and connecting the hub to the cutter body arm segments so that the hub and the at least one ring are connected around the axis of rotation. 
         [0007]    This method can result in a cutter head which is easier to form due to the location of the connections between cutter body arm segments and the hub. 
         [0008]    According to an embodiment, the step of forming at least one ring with integral cutter body arm segments comprises forming a base ring with integral cutter body arm segments. 
         [0009]    According to an embodiment, the step of forming a hub comprises forming a hub with hub arm segments. Optionally, the hub arm segments could be formed integral with the hub. Optionally, the embodiment could include connecting the hub arm segments to the hub and/or the cutter body arm segments. 
         [0010]    According to an embodiment, the step of forming at least one ring with integral cutter body arm segments comprises forming a supplemental ring with integral cutter body arm segments. Optionally, the step of connecting the hub to the cutter body arm segments comprises connecting the hub to the cutter body arm segments extending from the supplemental ring; and connecting the supplemental ring to the base ring such that the supplemental ring is connected between the base ring and the hub. Optionally, at least a portion of the cutter body arm segments extending from the supplemental ring connect to both the hub and to the base ring. Optionally, these can connect through arm segments connected to and/or formed integrally to the hub and/or the base ring. 
         [0011]    According to an embodiment, the hub, hub arm segments and/or at least one ring with cutter body arm segments are connected by welding. Due to the location of the connections being easily accessible, the welding is easier and can result in the use of less materials than past systems. 
         [0012]    According to an embodiment, the hub, hub arm segments, cutter body arm segments and/or the at least one ring are connected to loose arm segments. 
         [0013]    According to an embodiment, a cutter head with an axis of rotation comprises at least one ring; a hub positioned rotationally symmetric and axially displaced from the at least one ring; and a plurality of arms extending between the at least one ring and the hub. Each arm comprises a first arm segment extending from and formed integral with the at least one ring. Optionally, each arm can further comprise a second arm segment extending from the hub, wherein the first arm segment is connected to the second arm segment to connect the at least one ring to the hub. Optionally, the second arm segment can be formed integral to the hub. Optionally, each of the plurality of arms further comprises third arm segments. 
         [0014]    According to an embodiment, the at least one ring comprises a base ring and/or a supplemental ring. 
         [0015]    According to an embodiment, third arm segments extend from and are formed integral with a supplemental ring, and the supplemental ring connects to the first arm segments and/or the second arm segments through the third arm segments. Optionally, the third arm segments extend circumferentially inward from the supplemental and/or the third arm segments extend circumferentially outward from the supplemental ring. 
         [0016]    According to an embodiment, the first arm segments, the second arm segments and/or the third arm segments are connected by welding and each of the plurality of arms comprises at least one weld zone. 
         [0017]    According to an embodiment, the second arm segments and the hub are formed integrally. 
         [0018]    According to an embodiment, the first arm segments, the second arm segments and/or the third arm segments, the hub and/or the at least one ring are connected to loose arm segments. 
         [0019]    According to a further aspect, there is provided a vessel comprising a cutter head according to any one of the preceding embodiments. 
         [0020]    According to an embodiment, a supplemental ring for a cutter head with a hub, a base ring and an axis of rotation comprises a ring portion with integral cutter body arm segments; and connection surfaces on each of the cutter body arm segments for connecting to arm segments, the hub and/or the base ring. When the cutter body arm segments are connected to the arm segments, the hub and/or the base ring; the hub, the supplemental ring and the base ring are positioned around the axis of rotation with the supplemental ring positioned between the base ring and the hub. 
         [0021]    According to an embodiment, the cutter body arm segments extend circumferentially inward from the supplemental ring to connect to arm segments and/or to the hub and/or the cutter body arm segments extend circumferentially outward from the supplemental ring to connect to arm segments and/or to the base ring. 
         [0022]    According to an embodiment, a base ring for a cutter head with a hub and an axis of rotation comprises a base ring with integrally formed cutter body arm segments; and connection surfaces on each of the cutter body arm segments for connecting to additional arm segments, a supplemental ring, and/or the hub. When the cutter body arm segments are connected to additional arm segments, a supplemental ring, and/or the hub, the base ring connects to the hub and is positioned axially rearward from the hub around the axis of rotation. 
         [0023]    By forming at least one ring for the cutter with integral arm segments, the cutter is easier to form due to the connection points being more accessible. When welding is used for connection, less materials are required due to the forming of at least one ring with integral arm segments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1  schematically illustrates an example vessel with a cutter head. 
           [0025]      FIG. 2A  shows a schematic perspective view of a first embodiment of a cutter head. 
           [0026]      FIG. 2B  shows a top view of the cutter head of  FIG. 2A . 
           [0027]      FIG. 3C  shows a cross-sectional view of  FIG. 2A . 
           [0028]      FIG. 2D  shows an exploded view of the cutter head of  FIG. 2A . 
           [0029]      FIG. 3A  shows a perspective view of a second embodiment of a cutter head. 
           [0030]      FIG. 3B  shows a side view of the cutter head of  FIG. 3A . 
           [0031]      FIG. 3C  shows a top view of the cutter head of  FIG. 3A . 
           [0032]      FIG. 3D  shows a perspective view of a hub with hub arms from the cutter head of  FIGS. 3A-3C . 
           [0033]      FIG. 3E  shows a perspective view of a supplemental ring from the cutter head of  FIGS. 3A-3C . 
           [0034]      FIG. 3F  shows a top view of the supplemental ring of  FIG. 3E . 
           [0035]      FIG. 3G  shows a perspective view of a base ring from the cutter head of  FIGS. 3A-3C . 
           [0036]      FIG. 3H  shows a perspective view of a cutter body arm from the cutter head of  FIGS. 3A-3C . 
       
    
    
     DETAILED DESCRIPTION 
       [0037]      FIG. 1  schematically illustrates an example vessel  10  with a cutter head  12  with axis of rotation RA, and suction tube  14 . Vessel  10  can be, for example, a cutter-suction dredger. 
         [0038]    As described in the background, cutter head  12  is connected to suction tube  14 , and is used to cut hard surface materials, such as rock. Cutter head  12  has a hub  16  (see  FIG. 2 ) which can be connected to and driven by a drive shaft (not shown) to rotate cutter head  12  around axis of rotation RA. The cut material is then drawn into suction tube  14  and transported away from the cutter head  12 . 
         [0039]      FIG. 2A  shows a schematic perspective view of a first embodiment of a cutter head  12 ,  FIG. 2B  shows a top view of cutter head  12 ,  FIG. 2C  shows a cross-sectional view of cutter head  12 , and  FIG. 2D  shows an exploded view of cutter head  12 . Cutter head  12  includes hub  16  with hub diameter D H , hub arm segments  18 , base ring  20  with base ring diameter D B , cutter body arm segments  22 , weld zones  24  and axis of rotation RA. In  FIGS. 2A-2D , cutter head  12  is shown with only two cutter body arm segments  22  and two hub arm segments  18  for viewing purposes only. Typical cutter heads  12  would include a plurality of additional arm segments joining hub  16  with base ring  20 . 
         [0040]    Cutter body arm segments  22  are formed integral to base ring  20 , and can be formed through casting or other means. Hub arm segments  18  can be formed separately from hub as loose arm segments and then can be connected to hub  16 . In other embodiments, hub arm segments  18  may be formed integrally with hub  16 . Hub  16  has a hub diameter D H  which is typically smaller then base ring diameter D B . Arm segments  22  and  18  typically converge towards the axis of rotation RA in a direction from base ring  20  to hub  16 . 
         [0041]    In the embodiment shown, hub arm segments  18  extend radially and axially outward from hub  16  and are shorter in length than cutter body arm segments  22 . Hub arm segments  18  generally extend symmetrically around the axis of rotation RA when connected to hub  16 . Cutter body arm segments  22  extend axially and radially inward from base ring  20 . In some embodiments, hub arm segments  18  and/or cutter body arm segments  22  may only extend in the axial or radial direction and/or have different shapes, directions and lengths. 
         [0042]    Hub arm segments  18  connect to cutter body arm segments  22  to join hub  16  with base ring  20  at weld zone  24 , thereby forming cutter head  12 . When hub arm segments  18  connect to cutter body arm segments  22 , hub  16  is axially symmetric around the axis of rotation RA and axially displaced in a forward direction from base ring  20 . 
         [0043]    In the embodiment shown, hub arm segments  18  and cutter body arm segments  22  are joined by welding at weld zone  24 . In other embodiments, hub arm segments  18  and cutter body arm segments  22  can be joined by adhesives or other coupling means. 
         [0044]    By forming cutter head  12  with hub  16 , hub arm segments  18  and base ring  20  with integral cutter body arm segments  18 , weld zones  24  of cutter head  12  are easy to reach, making cutter head  12  easier to form than past cutter heads. Typically, past cutter heads were formed by initially forming a hub, a base ring and a plurality of arms to connect the hub to the base ring around the axis of rotation. The arms were individually welded to both the hub and the base ring. This construction required many full or semi-full penetration welds, which was very labour intensive and resulted in having to use a lot of material for the welds. Additionally, the location of the welds made them difficult to perform. By forming base ring  20  and/or hub  16  with integral arm segments  18 ,  22 , weld zones  24  to join arm segments  18 ,  22  are at a more accessible location, resulting in an easier and less labour-intensive weld. The welds to form cutter head  12  also use fewer materials due to the placement and the forming of cutter body arms  22  integrally with base ring  20 . 
         [0045]      FIG. 3A  shows a perspective view of a second embodiment of cutter head  12 ,  FIG. 3B  shows a side view of cutter head  12 , and  FIG. 3C  shows a top view of the cutter head  12 .  FIGS. 3D-3H  show the individual components of cutter head  12 , including a perspective view of hub  16  ( FIG. 3D ), a perspective view of supplemental ring  26  ( FIG. 3E ), a top view of supplemental ring  26  ( FIG. 3F ), a perspective view of a base ring  20  ( FIG. 3G ), and a perspective view of a cutter body arm  18  ( FIG. 3H ). Similar parts use the same numbers as in  FIGS. 2A-2C . 
         [0046]    Cutter head  12  of  FIGS. 3A-3C  includes hub  16  with hub diameter D H , hub arm segments  18 , base ring  20  with base ring diameter D B , cutter body arm segments  22 , weld zones  24 , axis of rotation RA and supplemental ring  26  with supplemental ring arms  28   a,    28   b  and supplemental ring diameter D s . 
         [0047]    Hub  16  includes integrally formed hub arms  18 . In the embodiment of  FIGS. 3A-3C , cutter body arms  22  are not formed integral to base ring  20 , and hub  16  and base ring  20  connect through supplemental ring  26  with supplemental arms  28   a,    28   b.    
         [0048]    Supplemental ring  26  is formed integral with supplemental arms  28   a,    28   b  extending circumferentially inward ( 28   b ) and circumferentially outward ( 28   a ) from supplemental ring  26 . Supplemental ring  26  with integral supplemental arms  28   a,    28   b  can be formed by casting or other means. In the embodiment shown, all supplemental arms  28   a  extend circumferentially outward from supplemental ring  26 , and only some supplemental arms  28   b  extend circumferentially inward from supplemental ring  26 . 
         [0049]    Cutter body arms  22  connect on one end to base ring  20  and on the other end to supplemental body arms  28   a.  Supplemental body arms  28   b  then connect to hub arms  18 , thereby connecting base ring  20  to hub  16 . Base ring  20 , supplemental ring  26  and hub  16  are axially symmetric around the axis of rotation, with supplemental ring  26  positioned axially forward from base ring  20  and hub  16  positioned axially forward from supplemental ring  26 . All connections can be formed, for example, by welding at weld zones  24 . 
         [0050]    As with cutter head  12  of  FIGS. 2A-2C , cutter head  12  of  FIGS. 3A-3H  is easier to form due to the weld zones  24  between hub arms  18  and supplemental arms  28   b  as well as between supplemental arms  28   a  and cutter body arms  22 . By forming supplemental ring  26  with integral supplemental arms  28   a,    28   b  and optionally forming hub  16  with integral hub arms  18 , weld zones  24  are more accessible. This results in cutter body  12  being easier to form and requiring less welding materials than when welding past cutter heads which required individually welding each arm to the hub, base ring and possibly the supplemental ring. 
         [0051]    While supplemental ring  26  is shown to have five circumferentially inward supplemental arms  28   b  and ten circumferentially outward supplemental arms  28   a,  this is for example purposes only. Other example embodiments could include, but are not limited to, supplemental ring  26  having only circumferentially inward supplemental arms  28   b,  supplemental ring  26  having only circumferentially outward arms  28   a,  supplemental ring having only arms which extend both circumferentially inward and outward, and differing numbers, positioning and/or ratios of circumferentially outward arms  28   a  to circumferentially inward arms  28   b.  Additionally, the number, direction and/or placement of arms  18 ,  22 ,  28   a,    28   b  are shown for example purposes and can vary depending on cutter head  12  needs. For example, arms  18 ,  22  and/or  28   a,    28   b  can be angled toward the rotational axis RA in a direction from the base ring to the hub providing a ball-shaped cutter head for cutting capabilities in the radial and axial direction. 
         [0052]    While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.