Eddy current testing apparatus and eddy current testing method

Abstract

The eddy current testing apparatus includes a probe having an eddy current testing sensor including a pair of eddy current testing coils. The apparatus also includes an eddy current testing flaw detector inputting detection signals from the eddy current testing sensor. The diameter of a magnetic core used in each of the pair of eddy current testing coils is within the range of 0.1 mm to 0.5 mm.

1 . An eddy current testing apparatus, comprising:
 a probe having an eddy current testing sensor including a pair of eddy current testing coils; and   an eddy current testing flaw detector inputting detection signals from said eddy current testing sensor,   wherein diameter of a magnetic core used in each of said pair of eddy current testing coils is within the range of 0.1 mm to 0.5 mm.   
   
   
       2 . The eddy current testing apparatus according to  claim 1 , wherein said pair of eddy current testing coils are disposed in said probe and each axial central line of said magnetic core crosses an external surface of said probe. 
   
   
       3 . The eddy current testing apparatus according to  claim 1 , further comprising:
 a rotating apparatus for rotating said probe.   
   
   
       4 . The eddy current testing apparatus according to  claim 1 , further comprising:
 a supporting member for supporting said probe by being inserted into a hole formed in a test object.   
   
   
       5 . The eddy current testing apparatus according to  claim 4 , wherein a probe holding member mounted on said probe is slidably attached to said supporting member. 
   
   
       6 . The eddy current testing apparatus according to  claim 5 , wherein a rotating apparatus for rotating said probe is mounted on said probe holding member. 
   
   
       7 . An eddy current testing apparatus, comprising:
 a probe having an eddy current testing sensor, and for performing eddy current testing of a test object;   an eddy current flaw detector for inputting a detection signal from said eddy current testing sensor; and   a supporting member for supporting said probe by being inserted into a hole formed in said test object.   
   
   
       8 . The eddy current testing apparatus according to  claim 7 , wherein a probe holding member mounted on said probe is slidably attached to said supporting member. 
   
   
       9 . The eddy current testing apparatus according to  claim 8 , wherein a rotating apparatus for rotating said probe is mounted on said probe holding member. 
   
   
       10 . An eddy current testing method for a turbine rotor comprising a disc, a plurality of turbine blades disposed along the periphery of said disc, and a plurality of pins for joining a blade fork portion formed on each of said plurality of turbine blades to a disc fork portion formed on said disc, comprising the steps of:
 inserting a probe having an eddy current testing sensor into a hole formed through the disc fork and blade fork by pulling out one of the plurality of pins in a state that said blade fork portion is still inserted into said disc fork portion; and   performing eddy current testing for at least part of internal surface of said hole by using said probe.   
   
   
       11 . An eddy current testing method for a turbine rotor comprising a disc, a plurality of turbine blades disposed along the periphery of said disc, and a plurality of pins for joining a blade fork portion formed on each of said plurality of turbine blades to a disc fork portion formed on said disc, comprising the steps of:
 pulling some of the plurality of pins out of said disc fork portion and said blade fork portion;   inserting a probe having an eddy current testing sensor into a hole formed through the disc fork and blade fork by pulling out one of the plurality of pins in a state that said blade fork portion is still inserted into said disc fork portion; and   performing eddy current testing for at least part of the internal surface of said hole by using said probe.   
   
   
       12 . The eddy current testing method according to claim  10 , wherein said pin to be pulled out is disposed at the outermost position of said plurality of pins disposed in a radial direction of said disc and joining said blade fork portion to said disc fork portion. 
   
   
       13 . An eddy current testing method for a turbine rotor comprising a disc, a plurality of turbine blades disposed along the periphery of said disc, and a plurality of pins for joining a blade fork portion formed on each of said plurality of turbine blades to a disc fork portion formed on said disc, comprising the steps of:
 inserting a probe having an eddy current testing sensor into a first hole formed through said disc fork portion and a first blade fork portion of a first turbine blade of said plurality of turbine blades by pulling out a first pin, which joins said first turbine blade to said disc, of said plurality of pins;   inserting a supporting member for supporting said probe into a second hole formed through said disc fork and a second blade fork portion of a second turbine blade, which is different from said first turbine blade and is positioned in said periphery, of said plurality of turbine blades by pulling a second pin, which joins said second turbine blade to said disc, of said plurality of pins; and   performing eddy current testing for at least part of the internal surface of said first hole by using said probe.   
   
   
       14 . The eddy current testing method according to  claim 13 , wherein said first pin being pulled out is disposed at the outermost position of said plurality of pins disposed in a radial direction of said disc and joining said first blade fork portion to said disc fork portion. 
   
   
       15 . The eddy current testing method according to  claim 13 , wherein said second pin being pulled out is disposed at the outermost position of said plurality of pins disposed in a radial direction of said disc and joining said second blade fork portion to said disc fork portion. 
   
   
       16 . The eddy current testing method according to  claim 13 , wherein said probe is inserted into said first hole by guiding a probe holding member attaching said probe along said supporting member. 
   
   
       17 . The eddy current testing method according to  claim 13 , wherein said supporting member is inserted into said second hole, and after insertion of said supporting member, said probe is inserted into said first hole. 
   
   
       18 . The eddy current testing method according to  claim 13 , wherein another supporting member for supporting said probe is inserted into a third hole formed through said disc fork portion and a third blade fork portion of a third turbine blade of said plurality of turbine blades by pulling out a third pin, which is positioned in said periphery and joins said third turbine blade to said disc, of said plurality of pins in a state that said first turbine blade is placed between said second turbine blade and said third turbine blade. 
   
   
       19 . The eddy current testing method according to  claim 18 , wherein said third pin being pulled out is disposed at the outermost position of said plurality of pins disposed in a radial direction of said disc and joining said third blade fork portion to said disc fork portion. 
   
   
       20 . An eddy current testing method for a turbine rotor comprising a disc, a plurality of turbine blades disposed along the periphery of said disc, and a plurality of pins for joining a blade fork portion formed on each of said plurality of turbine blades to a disc fork portion formed on said disc, comprising the steps of:
 pulling a first pin, which joins a first turbine blade of said plurality of turbine blades to said disc, of said plurality of pins out of a first blade fork portion of said first turbine blade;   pulling a second pin, which joins a second turbine blade of said plurality of turbine blades to said disc, of the plurality of pins out of said first blade fork portion a second blade fork portion of said second turbine blade;   inserting a probe having an eddy current testing sensor into a first hole formed through said disc fork portion and said first blade fork portion by pulling out said first pin;   inserting a supporting member for supporting said probe into a second hole formed through said disc fork and said second blade fork portion by pulling out said second pin; and   performing eddy current testing for at least part of the internal surface of said first hole by using said probe,   wherein said second turbine blade is different from the first turbine blade.   
   
   
       21 . The eddy current testing method according to  claim 20 , wherein said first pin being pulled out is disposed at the outermost position of said plurality of pins disposed in a radial direction of said disc and joining said first blade fork portion to said disc fork portion. 
   
   
       22 . The eddy current testing method according to  claim 20 , wherein said second pin being pulled out is disposed at the outermost position of said plurality of pins disposed in a radial direction of said disc and joining said second blade fork portion to said disc fork portion. 
   
   
       23 . The eddy current testing method according to  claim 20 , wherein said probe is inserted into said first hole by guiding a probe holding member attaching said probe along said supporting member. 
   
   
       24 . The eddy current testing method according to  claim 20 , wherein said supporting member is inserted into said second hole, and after insertion of said supporting member, said probe is inserted into said first hole. 
   
   
       25 . The eddy current testing method according to  claim 20 , wherein another supporting member for supporting said probe is inserted into a third hole formed through said disc fork portion and a third blade fork portion of a third turbine blade of said plurality of turbine blades by pulling out a third pin, which is positioned in said periphery and joins said third turbine blade to said disc, of said plurality of pins in a state that said first turbine blade is placed between said second turbine blade and said third turbine blade. 
   
   
       26 . The eddy current testing method according to  claim 25 , wherein said third pin being pulled out is disposed at the outermost position of said plurality of pins disposed in a radial direction of said disc and joining said third blade fork portion to said disc fork portion. 
   
   
       27 . An eddy current testing method for a turbine rotor comprising a disc, a plurality of turbine blades disposed along the periphery of said disc, and a plurality of pins for joining a blade fork portion formed on each of said plurality of turbine blades to a disc fork portion formed on said disc, said each turbine blade being joined to the disc by said plurality of pins disposed in a radial direction of said disc, comprising the steps of:
 pulling said pin disposed at the outermost position of said plurality of pins disposed in the radial direction for said each turbine blade, out of said disc fork portion and each blade fork portion;   inserting a probe having an eddy current testing sensor into a plurality of holes, which are formed through disc fork portion and corresponding blade fork portions by pulling said plurality of pins disposed at said outermost position, in succession in a state that said blade fork portions is still inserted into said disc fork portion; and   performing eddy current testing for at least part of internal surface of said hole by using said probe.   
   
   
       28 . The eddy current testing method according to  claim 27 , further comprising the steps of:
 pulling out another pin, which is disposed inside said pin pulled out, of said plurality of pins disposed in the radial direction and joining one of said blade fork portion to said disc fork portion, when there is a crack on at least part of internal surface of said hole formed through said one of said blade fork portions; and   inserting said probe into another hole formed through said disc fork portion and said one of said blade fork portions by pulling said another pin.   
   
   
       29 . The eddy current testing method according to  claim 10 , wherein said probe is a probe having said eddy current sensor including a magnetic core with a diameter within the range of 0.1 mm to 0.5 mm.