Cuttings removal wipers for cutter assemblies and method

Abstract

A wiper may be supported on at least one of a radially inwardly or radially outwardly facing dynamic interface surfaces of a pair surfaces on respective cutter journal and cutter shell. The wiper may be in the form of a low profile lug having a leading edge generally diagonally oriented relative to an axis of rotation of the cutter shell on the cutter journal. Thus, the leading edge of the wiper will move formation particles axially out from between the cutter journal and the cutter shell and away from a bearing seal. The wiper may have a height less than a regular clearance between the journal and the shell. A plurality of wipers may be supported on the dynamic interface surface of either the shell or the journal and may extend into close proximity to the oppositely facing dynamic interface surface of the other of the shell or the journal.

1 . A replaceable cutter assembly comprising:
 a journal having at least one journal bearing surface, the journal having at least one radially outwardly facing dynamic journal interface surface;   a cutter shell rotatably supported on the journal, the cutter shell having a cutter shell bearing surface and the cutter shell having at least one radially inwardly facing dynamic cutter shell interface surface; and   at least one wiper on the at least one of the interface surfaces of one of the journal and the cutter shell;   wherein the at least one wiper is proximate to and faces the at least one of the interface surfaces of the other of the journal and the cutter shell.   
   
   
       2 . The replaceable cutter assembly of  claim 1 , wherein the wiper is a low profile lug integrally formed on one of the journal and the cutter shell. 
   
   
       3 . The replaceable cutter assembly of  claim 1 , wherein:
 a rotational axis of the cutter shell on the journal defines an axial direction; and   the wiper has an edge that extends generally diagonally relative to the axial direction.   
   
   
       4 . The replaceable cutter assembly of  claim 1 , wherein:
 a rotational axis of the cutter shell on the journal defines an axial direction; and   the wiper has an edge that extends generally helically relative to the axial direction.   
   
   
       5 . The replaceable cutter assembly of  claim 1 , further comprising a plurality of wipers may include the at least one wiper, wherein the wipers protrude radially from the at least one of the interface surfaces. 
   
   
       6 . The replaceable cutter assembly of  claim 5 , wherein a rotational axis of the cutter shell defines an axial direction, the plurality of wipers comprises four permanent low profile lugs circumferentially spaced from each other on the at least one of the dynamic journal interface surfaces relative to the rotational axis, wherein the permanent low profile lugs further comprise edges that extend generally diagonally relative to the axial direction. 
   
   
       7 . The replaceable cutter assembly of  claim 1 , further comprising at least one seal sealingly contacting the cutter shell and the cutter journal between the dynamic interface surfaces of the cutter shell and the cutter journal on one axial side and the bearing surfaces of the cutter shell and the cutter journal on another axial side of the at least one seal. 
   
   
       8 . The replaceable cutter assembly of  claim 1 , further comprising:
 a plurality of radially outwardly facing dynamic journal interface surfaces including the at least one radially outwardly facing dynamic journal interface surface;   a plurality of radially inwardly facing dynamic cutter shell interface surfaces including the at least one radially inwardly facing dynamic cutter shell interface surface, the plurality of radially inwardly facing dynamic cutter shell interface surfaces forming respective pairs of interface surfaces with the plurality of radially outwardly facing dynamic journal interface surfaces; and   at least one of the wipers on at least one of the interface surfaces of each of the pairs of interface surfaces;   wherein each of the at least one of the wipers is proximate to and faces the other of the interface surfaces of each of the pairs of the interface surfaces.   
   
   
       9 . A replaceable cutter journal comprising:
 a journal having at least one journal bearing surface and at least one radially outwardly facing dynamic journal interface surface; and   at least one wiper on the at least one interface surface.   
   
   
       10 . The replaceable cutter journal of  claim 9 , wherein the radially outwardly facing dynamic journal interface surface comprises:
 at least one first portion having a first diameter; and   at least one second raised portion having a second diameter greater than the first diameter;   wherein the first and second portions extend along a common circumferential line.   
   
   
       11 . The replaceable cutter journal of  claim 9 , wherein:
 a rotational axis of the journal defines an axial direction; and   the radially outwardly facing dynamic journal interface surface extends circumferentially and is spaced proximally relative to the journal bearing surface in the axial direction.   
   
   
       12 . The replaceable cutter journal of  claim 9 , wherein:
 a rotational axis of the journal defines an axial direction; and   the wiper has an edge that extends generally diagonally relative to the axial direction.   
   
   
       13 . The replaceable cutter journal of  claim 9 , further comprising a plurality of wipers including the at least one wiper, wherein:
 the wipers form second portions of the radially outwardly facing dynamic journal interface surface; and   the wipers protrude radially from first portions of the at least one interface surface.   
   
   
       14 . The replaceable cutter journal of  claim 13 , wherein a rotational axis of the cutter shell defines an axial direction, the plurality of wipers comprises four permanent low profile lugs circumferentially spaced from each other on the dynamic journal interface surface relative to the rotational axis, wherein the permanent low profile lugs further comprise edges that extend generally diagonally relative to the axial direction. 
   
   
       15 . The replaceable cutter journal of  claim 9 , wherein at least one second portion of the radially outwardly facing dynamic journal interface surface comprises the at least one wiper integrally formed as one piece with a first portion of the radially outwardly facing dynamic journal interface surface. 
   
   
       16 . The replaceable cutter journal of  claim 9 , wherein the dynamic journal interface surface is on a separable piece removably attached to the journal. 
   
   
       17 . The replaceable cutter journal of  claim 16 , wherein the separable piece comprises a seal retainer. 
   
   
       18 . The replaceable cutter journal of  claim 9 , further comprising a plurality of radially outwardly facing dynamic journal interface surfaces including the at least one radially outwardly facing dynamic journal interface surface. 
   
   
       19 . The replaceable cutter journal of  claim 18 , wherein each of the radially outwardly facing dynamic journal interface surfaces is on a separable piece removably attached to a remainder of the journal. 
   
   
       20 . A replaceable cutter shell comprising:
 a cutter shell having at least one cutter shell bearing surface and at least one radially inwardly facing dynamic cutter shell interface surface; and   at least one wiper on the at least one interface surface.   
   
   
       21 . The replaceable cutter shell of  claim 20 , wherein the radially inwardly facing dynamic cutter shell interface surface comprises:
 at least one first portion having a first diameter; and   at least one second raised portion having a second diameter less than the first diameter;   wherein the first and second portions extend along a common circumferential line.   
   
   
       22 . The replaceable cutter shell of  claim 20 , wherein:
 a rotational axis of the cutter shell defines an axial direction; and   the radially inwardly facing dynamic journal interface surface extends circumferentially and is spaced proximally relative to the cutter shell bearing surface in the axial direction.   
   
   
       23 . The replaceable cutter shell of  claim 20 , wherein:
 a rotational axis of the cutter shell defines an axial direction; and   the wiper has an edge that extends generally diagonally relative to the axial direction.   
   
   
       24 . The replaceable cutter shell of  claim 20 , further comprising a plurality of wipers including the at least one wiper, wherein:
 the wipers form second portions of the radially inwardly facing dynamic cutter shell interface surface; and   the wipers protrude radially from first portions of the at least one interface surface.   
   
   
       25 . The replaceable cutter shell of  claim 24 , wherein a rotational axis of the cutter shell defines an axial direction, the plurality of wipers comprises four permanent low profile lugs circumferentially spaced from each other on the dynamic cutter shell interface surface relative to the rotational axis, wherein the permanent low profile lugs further comprise edges that extend generally diagonally relative to the axial direction. 
   
   
       26 . The replaceable cutter shell of  claim 20 , wherein at least one second portion of the radially inwardly facing dynamic journal interface surface comprises the at least one wiper integrally formed as one piece with a first portion of the radially inwardly facing dynamic journal interface surface. 
   
   
       27 . A separate piece removably attachable to at least one of a cutter assembly journal or a cutter assembly cutter shell, the separate piece comprising:
 a radially facing dynamic interface surface having at least a first portion and a second portion, the first and second portions having respective first and second diameters different from each other, the first and second portions extending along a common circumferential line; and   attachment structure on the separate piece for removably attaching the piece to at least one of a cutter assembly cutter journal and a cutter assembly cutter shell.   
   
   
       28 . The separate piece of  claim 27 , wherein the separate piece comprises a seal retainer having a seal retaining structure. 
   
   
       29 . The separate piece of  claim 27 , wherein at least one of the first and second portions forms low profile lugs relative to the other of the first and second portions. 
   
   
       30 . A method of inhibiting entry of debris into a raise bore cutter assembly, the method comprising:
 sweeping a first radially facing dynamic interface surface with at least one wiper disposed on a second oppositely radially facing dynamic interface surface; and   moving debris axially away from at least one seal and at least one bearing of the cutter assembly;   wherein the steps of sweeping and moving comprise automatically sweeping and moving during regular rotation of a cutter shell of the cutter assembly relative to a cutter journal of the cutter assembly.   
   
   
       31 . The method of  claim 30 , wherein the steps of sweeping and moving comprise:
 presenting a leading edge of the at least one wiper transverse to an axial direction defined by an axis of rotation of the cutter shell relative to the cutter journal; and   moving the leading edge of the at least one wiper circumferentially along the second oppositely radially facing dynamic interface surface.   
   
   
       32 . The method of  claim 30 , further comprising:
 sweeping a plurality of radially facing dynamic interface surfaces including the first radially facing dynamic interface surface with a plurality of wipers including the at least one wiper, the plurality of wipers disposed on a plurality of oppositely facing dynamic interface surfaces including the second oppositely radially facing dynamic interface surface; and   moving debris axially away from a plurality of seals including the at least one seal and moving debris axially away from a plurality of bearings including the at least one bearing of the cutter assembly;   wherein the steps of sweeping and moving comprise automatically sweeping and moving during regular rotation of the cutter shell of the cutter assembly relative to the cutter journal of the cutter assembly.