Flexible shaft with helical square end

Abstract

A flexible shaft having at least one end formed to have a helical square shape, wherein successive cross-sections have square shapes progressively rotated with respect to each other. The overall rotation from where the square cross-section begins to the adjacent end of the shaft is preferably in the range of 10 to 20 degrees. The helical square end is preferably shaped by swaging utilizing helical square dies preferably made by electron discharge machining. When the helical square end of the flexible shaft is forced into a mating square opening of an end fitting, the helical square configuration of the shaft end causes it to be deformed and bind tightly in the fitting with an interference fit, thus reducing vibration and noise when the shaft is rotated. Instead of a helical square shape, the end of the flexible shaft may alternatively have another helical polygonal shape.

We claim:  
     
         1 . A flexible shaft comprising at least one layer of wire wound on another wire or wires, said shaft having at least one end portion with a helical square configuration.  
     
     
         2 . The flexible shaft according to  claim 1 , wherein successive cross-sections of said end portion have square shapes of substantially identical cross-section progressively rotated with respect to each other.  
     
     
         3 . The flexible shaft according to  claim 1  or  2 , wherein the angle of rotation from where the square cross-section begins to the adjacent end of the shaft is in the range of 10 to 20 degrees.  
     
     
         4 . A process for manufacturing a flexible shaft having a helical square configuration, comprising the steps of: 
 providing a flexible shaft comprising at least one layer of wire wound on another wire or wires; and    forming at least one end portion of said shaft to a helical square configuration.    
     
     
         5 . The process according to  claim 4 , wherein said at least one end portion is formed by swaging.  
     
     
         6 . The process according to  claim 5 , wherein said swaging step is carried out utilizing a die set having a helical square configuration, said set comprising four dies, each die being adapted to form one side of said configuration.  
     
     
         7 . A process for manufacturing a helical square flexible shaft, comprising the steps of: 
 winding at least one layer of wire on another wire or wires to form a flexible shaft;    providing a set of four dies having a helical square configuration; and    swaging at least one end portion of said flexible shaft to form said end portion to a helical square shape, utilizing said set of dies, each die forming one side of said configuration.    
     
     
         8 . The process according to  claim 6  or  7 , wherein said dies are manufactured by electron discharge machining.  
     
     
         9 . The process according to  claim 4 ,  5 ,  6 , or  7 , comprising the additional step of forcing said formed end portion into a cavity of a fitting having a corresponding square cross-section.  
     
     
         10 . A flexible shaft comprising at least two contiguous layers of wire wound on a mandrel wire, at least one end portion of said shaft having a helical square configuration.  
     
     
         11 . The flexible shaft according to  claim 10 , wherein said shaft has two end portions each having a helical square configuration.  
     
     
         12 . The flexible shaft according to  claim 10  wherein the end of said shaft adjacent said end portion is rotated by an angle in the range of 10 to 20 degrees with respect to the part of said shaft where said end portion begins.  
     
     
         13 . A flexible shaft having at least one end portion formed to have a helical polygonal shape.  
     
     
         14 . The flexible shaft according to  claim 13 , wherein successive cross-sections of said end portion have polygonal shapes progressively rotated with respect to each other.  
     
     
         15 . The flexible shaft according to  claim 13  or  14 , wherein the angle of rotation from where the polygonal cross-section begins to the adjacent end of the shaft is in the range of 10 to 20 degrees.  
     
     
         16 . A flexible shaft having at least one end portion formed to have a helical noncircular shape.  
     
     
         17 . The flexible shaft according to  claim 16 , wherein successive cross-sections of said end portion have noncircular shapes progressively rotated with respect to each other.  
     
     
         18 . The flexible shaft according to  claim 16  or  17 , wherein the angle of rotation from where the noncircular cross-section begins to the adjacent end of the shaft is in the range of 10 to 20 degrees.  
     
     
         19 . A process for manufacturing a helical noncircular flexible shaft, comprising the steps of: 
 winding at least one layer of wire on another wire or wires to form a flexible shaft; and    forming at least one end portion of said shaft to a helical noncircular shape.    
     
     
         20 . The process according to  claim 19 , wherein said at least one end portion is formed by swaging.  
     
     
         21 . The process according to  claim 20 , wherein said swaging step is carried out utilizing dies having a helical noncircular configuration.  
     
     
         22 . A process for manufacturing a flexible shaft having a helical noncircular end portion, comprising the steps of: 
 winding at least one layer of wire on another wire or wires to form a flexible shaft;    providing a set of dies having a helical noncircular configuration; and    swaging at least one end portion of said flexible shaft to form said end portion to a helical noncircular shape, utilizing said set of dies.    
     
     
         23 . The process according to  claim 21  or  22 , wherein said dies are manufactured by electron discharge machining.  
     
     
         24 . The process according to  claim 21  or  22 , wherein said end portion is polygonal and the number of dies in said die set is equal to the number of sides of said end portion, each die forming one side of said end portion during said swaging step.  
     
     
         25 . The process according to  claim 19 ,  20 ,  21 , or  22 , comprising the additional step of forcing said formed end portion into a cavity having a complementary square cross-section, wherein a part of said end portion engages walls of said cavity with an interference fit.  
     
     
         26 . A flexible shaft having at least one end portion formed to have a helical noncircular shape, and a fitting having a cavity with a cross-sectional shape different from the cross-sectional shape of at least an end part of said end portion, said end part being disposed within said cavity and having an interference fit therewith.  
     
     
         27 . The flexible shaft according to  claim 26 , wherein the cross-sectional shape of said end portion is polygonal.  
     
     
         28 . The flexible shaft according to  claim 26  or  27 , wherein said end portion has four sides and the cross-sectional shape of said end portion is square.  
     
     
         29 . The process according to  claim 6  or  7 , wherein said dies are manufactured by abrasive grinding.  
     
     
         30 . The process according to  claim 21  or  22 , wherein said dies are manufactured by abrasive grinding.