Shaft holding sleeve, shaft diameter enlarging apparatus and jig for shaft diameter enlarging apparatus

Abstract

A shaft holding sleeve is inserted in a fitting hole of a compressing machine of a shaft diameter enlarging apparatus that applies an axial compression stress to a shaft stock to hold an end portion of the shaft stock during a shaft diameter enlarging process for radially enlarging a portion of the shaft stock. The shaft holding sleeve includes a front end surface to be inserted in the fitting hole, an exposed portion to be exposed to an outside of the fitting hole, and at least one air communication passage extending from the front end surface to a surface of the exposed portion. A jig may be attached to the shaft diameter enlarging apparatus to facilitate the insertion of the shaft holding sleeve into the fitting hole.

1 - 17 . (canceled) 
     
     
         18 . A shaft holding sleeve to be inserted in a fitting hole of a compressing machine that applies an axial compression stress to a shaft stock to hold an end portion of the shaft stock during a shaft diameter enlarging process for radially enlarging a portion of the shaft stock, the shaft holding sleeve comprising:
 a front end surface to be inserted in the fitting hole;   an exposed portion to be exposed to an outside of the fitting hole; and   at least one air communication passage extending from the front end surface to a surface of the exposed portion.   
     
     
         19 . The shaft holding sleeve according to  claim 18 , wherein the air communication passage comprises a groove formed on an outer peripheral surface of the shaft holding sleeve. 
     
     
         20 . The shaft holding sleeve according to  claim 18 , wherein the air communication passage comprises a through hole extending from the front end surface to an opposite end surface of the shaft holding sleeve. 
     
     
         21 . The shaft holding sleeve according to  claim 18 , comprising an attaching portion provided on an outer peripheral surface of the shaft holding sleeve, the attaching portion being configured such that a lifting lug is attachable and detachable with respect to the attaching portion. 
     
     
         22 . The shaft holding sleeve according to  claim 18 , comprising a grip portion provided on the exposed portion. 
     
     
         23 . The shaft holding sleeve according to  claim 18 , comprising a surface-hardened portion at least at an opening portion of the shaft holding sleeve from which the end portion of the shaft stock is inserted into the shaft holding sleeve. 
     
     
         24 . The shaft holding sleeve according to  claim 23 , wherein a Vickers hardness of the surface-hardened portion is equal to or greater than HV1200. 
     
     
         25 . The shaft holding sleeve according to  claim 18 , comprising:
 a cylindrical outer sleeve adapted to be fixed to the compressing machine; and   an inner sleeve provided inside the outer sleeve, the inner sleeve being configured to accommodate the end portion of the shaft stock and arranged to contact a radially enlarged portion of the shaft stock,   wherein the outer sleeve and the inner sleeve are provide with an engaging structure configured to prevent a relative movement of the inner sleeve with respect to the outer sleeve in a direction opposite to a compression direction in which the shaft stock is compressed.   
     
     
         26 . The shaft holding sleeve according to  claim 25 , wherein the engaging structure is provided on an inner peripheral surface of the outer sleeve and on an outer peripheral surface of the inner sleeve. 
     
     
         27 . The shaft holding sleeve according to  claim 26 , wherein the engaging structure comprises an annular concave-convex portion. 
     
     
         28 . The shaft holding sleeve according to  claim 27 , wherein each concave portion and convex portion of the engaging structure are configured in a saw-tooth shape extending away from a center axis of the outer sleeve and the inner sleeve in the direction opposite to the compression direction. 
     
     
         29 . The shaft holding sleeve according to  claim 28 , wherein the inner peripheral surface of the outer sleeve and the outer peripheral surface of the inner sleeve are formed in a tapered shape extending away from the center axis of the outer sleeve and the inner sleeve in the direction opposite to the compression direction. 
     
     
         30 . The shaft holding sleeve according to  claim 27 , wherein a depth of each concave portion and a height of each convex portion of the engaging structure are equal to or greater than 50 μm and equal to or smaller than 1% of an outer diameter of the inner sleeve. 
     
     
         31 . The shaft holding sleeve according to  claim 25 , comprising a surface-hardened portion at least at an opening portion of the inner sleeve from which the end portion of the shaft stock is inserted into the shaft holding sleeve. 
     
     
         32 . The shaft holding sleeve according to  claim 31 , wherein a Vickers hardness of the surface-hardened portion is equal to or greater than HV1200. 
     
     
         33 . A shaft diameter enlarging apparatus comprising:
 a pair of shaft holding sleeves to hold respective end portions of a shaft stock during a shaft diameter enlarging process for radially enlarging a portion of the shaft stock;   a compressing machine having fitting holes into which the pair of shaft holding sleeves are inserted respectively, the compressing machine being configured to compress the shaft stock having the respective end portions held by the pair of shaft holding sleeves in an axial direction of the shaft stock; and   a load generation device configured to apply, to an intermediate portion of the shaft stock having the respective end portions held by the pair of shaft holding sleeves, an alternating load in a direction intersecting the axial direction,
 wherein each of the shaft holding sleeves comprises: 
 a front end surface to be inserted in a corresponding one of the fitting holes; 
 an exposed portion to be exposed to an outside of the corresponding one of the fitting holes; and at least one air communication passage extending from the front end surface to a surface of the exposed portion. 
   
     
     
         34 . A jig for use with a shaft diameter enlarging apparatus including a pair of shaft holding sleeves to hold respective end portions of a shaft stock during a shaft diameter enlarging process for radially enlarging a portion of the shaft stock, a compressing machine having fitting holes into which the pair of shaft holding sleeves are inserted respectively, the compressing machine being configured to compress the shaft stock having the respective end portions held by the pair of shaft holding sleeves in an axial direction of the shaft stock, and a load generation device configured to apply, to an intermediate portion of the shaft stock having the respective end portions held by the pair of shaft holding sleeves, an alternating load in a direction intersecting the axial direction, wherein each of the shaft holding sleeves has a front end surface to be inserted in a corresponding one of the fitting holes an exposed portion to be exposed to an outside of the corresponding one of the fitting holes, and at least one air communication passage extending from the front end surface to a surface of the exposed portion,
 the jig comprising a mounting surface on which one of the shaft holding sleeves is mounted when inserting the one of the shaft holding sleeves into the corresponding one of the fitting holes,   wherein, in a state in which the jig is attached to an opening edge portion of the corresponding one of the fitting holes, the mounting surface is flush with an inner peripheral surface of the corresponding one of the fitting holes.