Assembly and method of attaching stub shaft to drum of axial compressor rotor shaft

Abstract

An assembly and method for an axial compressor includes an axial shaft extending between an inlet casing and a discharge casing along the longitudinal length of a compressor housing. The axial shaft assembly includes a first stub shaft, a second stub shaft, and a hollow shaft drum having a longitudinal axis. The first stub shaft and the second stub shaft are coupled to opposing ends of the shaft drum along its longitudinal axis. A plurality of keys is disposed in a radial arrangement near the outer circumference of the first and second stub shafts and the shaft drum. A plurality of pins engage the plurality of keys, whereby the pins prevent the shaft drum from rotating axially relative to the first stub shaft and the second stub shaft and prevent the shaft drum from axially and radially separating from the stub shafts.

The invention claimed is: 
     
         1 . A shaft assembly for an axial compressor, the shaft assembly comprising:
 a first stub shaft;   a second stub shaft;   a hollow shaft drum having a longitudinal axis, the first stub shaft and the second stub shaft coupled to opposing ends of the shaft drum along the longitudinal axis;   a plurality of keys disposed in a radial arrangement proximate to the outer circumference of the first and second stub shafts and the shaft drum; and   a plurality of pins engaging the plurality of keys,   wherein the pins prevent the shaft drum from rotating axially relative to the first stub shaft and the second stub shaft and prevent the shaft drum from axially and radially separating from the stub shafts.   
     
     
         2 . The shaft assembly according to  claim 1 , further comprising:
 a plurality of shoulder structures provided on each of the first stub shaft and the second stub shaft; and   a plurality of shoulder recesses provided at opposing ends of the shaft drum along the longitudinal axis,   wherein the plurality of shoulder structures are operative for engaging the plurality of shoulder recesses to form a rabbet fit between the first and second stub shafts and the shaft drum for maintaining coaxial arrangement of the shaft assembly.   
     
     
         3 . The shaft assembly according to  claim 1 , wherein each pin is dimensioned to be larger than the corresponding key to allow for an interference fit between the pin and the key. 
     
     
         4 . The shaft assembly according to  claim 1 , wherein each key comprises a slot formed on the first and second stub shafts and a corresponding slot formed on the shaft drum. 
     
     
         5 . The shaft assembly according to  claim 1 , wherein each pin includes a recess substantially coaxial with a longitudinal axis of the pin, the recess adapted for facilitating insertion of the pin into the corresponding key. 
     
     
         6 . The shaft assembly according to  claim 1 , further comprising one or more through-bolts extending axially between the first and second stub shafts through the shaft drum, the one or more through-bolts providing a closing force to prevent relative movement between the first and second stub shafts and the shaft drum. 
     
     
         7 . The shaft assembly according to  claim 6 , wherein each through-bolt includes threaded ends and a nut is provided at each threaded end to tighten the through-bolt and couple the first and second stub shafts to the shaft drum. 
     
     
         8 . An axial compressor comprising:
 a housing having an inlet casing provided at one end and a discharge casing provided at an opposing end;   an axial shaft assembly rotatably disposed inside the housing, the axial shaft assembly extending between the inlet casing and the discharge casing along a longitudinal length of the housing;   a plurality of stator blades extending radially inward from an inner surface of the housing;   a plurality of rotor blades extending radially outward from an outer surface of the axial shaft assembly,   wherein the axial shaft assembly comprises:   a first stub shaft;   a second stub shaft;   a hollow shaft drum having a longitudinal axis, the first stub shaft and the second stub shaft coupled to opposing ends of the shaft drum along the longitudinal axis;   a plurality of keys disposed in a radial arrangement proximate to the outer circumference of the first and second stub shafts and the shaft drum; and   a plurality of pins engaging the plurality of keys, wherein the pins prevent the shaft drum from rotating axially relative to the first stub shaft and the second stub shaft and prevent the shaft drum from axially and radially separating from the stub shafts.   
     
     
         9 . The axial compressor of  claim 8 , further comprising:
 a plurality of shoulder structures provided on the first stub shaft and the second stub shaft; and   a plurality of shoulder recesses provided at opposing ends of the shaft drum along its longitudinal axis,   wherein the plurality of shoulder structures are operative for engaging the plurality of shoulder recesses to form a rabbet fit between the first and second stub shafts and the shaft drum for maintaining coaxial arrangement of the shaft assembly.   
     
     
         10 . The axial compressor of  claim 8 , wherein each pin is dimensioned to be larger than the corresponding key to allow for an interference fit between the pin and the key. 
     
     
         11 . The axial compressor of  claim 8 , wherein each key comprises a slot formed on the first and second stub shafts and a corresponding slot formed on the shaft drum. 
     
     
         12 . The axial compressor of  claim 8 , wherein each pin includes a recess substantially coaxial with a longitudinal axis of the pin, the recess adapted for facilitating insertion of the pin into the corresponding key. 
     
     
         13 . The axial compressor of  claim 8 , further comprising one or more through-bolts extending axially between the first and second stub shafts through the shaft drum, the one or more through-bolts providing a closing force to prevent relative movement between the first and second stub shafts and the shaft drum. 
     
     
         14 . The axial compressor of  claim 13 , wherein each through-bolt includes threaded ends and a nut is provided at each threaded end to tighten the through-bolt and couple the first and second stub shafts to the shaft drum. 
     
     
         15 . A method of attaching stub shafts to a shaft drum of an axial compressor, the method comprising the steps of:
 providing an axial shaft assembly comprising:
 a first stub shaft; 
 a second stub shaft; and 
 a hollow shaft drum having a longitudinal axis, the first stub shaft and the second stub shaft coupled to opposing ends of the shaft drum along its longitudinal axis; 
   providing a plurality of keys disposed in a radial arrangement near the outer circumference of the first and second stub shafts and the shaft drum; and   providing a plurality of pins engaging the plurality of keys, wherein the pins prevent the shaft drum from rotating axially relative to the first stub shaft and the second stub shaft and prevent the shaft drum from axially and radially separating from the stub shafts.   
     
     
         16 . The method of  claim 15 , further comprising the steps of:
 providing a plurality of shoulder structures provided on the first stub shaft and the second stub shaft; and   providing a plurality of shoulder recesses provided at opposing ends of the shaft drum along its longitudinal axis,   wherein the plurality of shoulder structures are operative for engaging the plurality of shoulder recesses to form a rabbet fit between the first and second stub shafts and the shaft drum for maintaining coaxial arrangement.   
     
     
         17 . The method of  claim 15 , wherein each pin is dimensioned to be larger than the corresponding key to allow for an interference fit between the pin and the key. 
     
     
         18 . The method of  claim 15 , wherein each key comprises a slot formed on the first and second stub shafts and a corresponding slot formed on the shaft drum. 
     
     
         19 . The method of  claim 15 , further comprising the step of providing one or more through-bolts extending axially between the first and second stub shafts through the shaft drum, the one or more through-bolts providing a closing force to prevent relative movement between the first and second stub shafts and the shaft drum. 
     
     
         20 . The method of  claim 19 , wherein each through-bolt includes threaded ends and a nut is provided at each threaded end to tighten the through-bolt and couple the first and second stub shafts to the shaft drum.