Bearing surface layer for magnetic motor

Abstract

A method for making a magnetic linear motor shaft including thermal treatment to temporarily change the dimensions of various shaft components to allow tight interference fit assembly. The magnetic motor includes a core piece, annular magnets and pole pieces.

1 .- 22 . (canceled) 
   
   
       23 . A method of assembling a magnetic motor comprising a core piece, annular magnets and pole pieces, said method comprising:
 stacking said annular magnets and said pole pieces in alternating fashion around said core piece to form a stack sub-assembly having a predetermined outer diameter;   forming a shaft sleeve having a predetermined inner diameter substantially equal to or less than said predetermined outer diameter of said stack sub-assembly;   cooling said stack sub-assembly until said predetermined outer diameter is decreased relative to said predetermined inner diameter by an amount sufficient to allow said cooled stack sub-assembly to be inserted into said shaft sleeve; and   inserting said cooled stack sub-assembly into said shaft sleeve to form a shaft assembly, thereby providing an extremely tight interference fit between said shaft sleeve and said stack sub-assembly as said stack sub-assembly expands back to said predetermined outer diameter provided before said cooling and inserting steps.   
   
   
       24 . The method of  claim 23 , wherein said cooling step comprises cooling said stack sub-assembly to at least 0 degrees Fahrenheit. 
   
   
       25 . The method of  claim 23 , further comprising heating said shaft sleeve, said inserting step comprising inserting said cooled stack sub-assembly into said heated shaft sleeve, whereby said extremely tight interference fit is provided as said stack sub-assembly expands back to said predetermined outer diameter and as said shaft sleeve contracts back to said predetermined inner diameter provided before said cooling and inserting steps. 
   
   
       26 . The method of  claim 25 , wherein said heating step comprises heating said shaft sleeve to at least 275 degrees Fahrenheit. 
   
   
       27 . The method of  claim 23 , further comprising machining an outer surface of said stack sub-assembly to said predetermined outer diameter after said stacking step. 
   
   
       28 . The method of  claim 23 , said method further comprising bathing said magnets and said pole pieces in epoxy prior to said stacking step. 
   
   
       29 . The method of  claim 28 , said method further comprising baking said stack sub-assembly after said bathing step to set said epoxy such that said epoxy forms a thin layer surrounding said stack sub-assembly. 
   
   
       30 . The method of  claim 23 , wherein said pole pieces comprise steel. 
   
   
       31 . The method of  claim 23 , wherein said pole pieces comprise at least one of mild steel, silicon iron BFM, 1018 steel, 4130 steel and low carbon steel. 
   
   
       32 . The method of  claim 23 , wherein said stacking step further comprises stacking annular spacers around the outside of said annular magnets. 
   
   
       33 . The method of  claim 23 , further comprising finishing an outer surface of said shaft assembly by grinding or lathing. 
   
   
       34 . The method of  claim 23 , further comprising providing a fixture for securing said core piece thereto before said stacking step. 
   
   
       35 . The method of  claim 23 , further comprising applying unset epoxy at least to the ends of said annular magnets and said pole pieces immediately prior to said stacking step. 
   
   
       36 . A method of assembling a magnetic motor comprising a core piece, annular magnets and pole pieces, said method comprising:
 stacking said annular magnets and said pole pieces in alternating fashion around said core piece to form a stack sub-assembly having a predetermined outer diameter;   forming a shaft sleeve having a predetermined inner diameter substantially equal to or less than said predetermined outer diameter of said stack sub-assembly;   cooling said stack sub-assembly to at least 0 degrees Fahrenheit to decrease said predetermined outer diameter relative to said predetermined inner diameter;   heating said shaft sleeve by an amount sufficient to allow said cooled stack sub-assembly to be inserted into said heated shaft sleeve; and   inserting said cooled stack sub-assembly into said heated shaft sleeve to form a shaft assembly, thereby providing an extremely tight interference fit between said shaft sleeve and said stack sub-assembly as said stack sub-assembly expands back to said predetermined outer diameter and said shaft sleeve contracts back to said predetermined inner diameter provided before said cooling and inserting steps.