Extruded nut formation

Abstract

A method of forming a sheet metal part including a nut structure by providing a sheet of metal, forming a tubular structure projecting integrally from the main body of the sheet, and tapping the tubular structure to form an internal screw thread within the tubular structure. The method is carried out on a press having a plurality of spaced stations including a punch station and a working station. The tubular structure is formed by punching a hole in the sheet at the punch station and thereafter forming the tubular structure in surrounding relation to the hole in a single hit of the press at the working station. The hole is punched in the sheet utilizing a punch and die wherein the diameter of the die is no greater than approximately five percent greater than the diameter of the punch whereby to provide a hole having a cleanly cut sidewall and thereby preclude splitting of the metal of the sheet as the tubular structure is formed at the working station. A coin formation is also formed in the single hit of the press at the working station to accommodate the head of an associated threaded plug adapted to be threaded into the internally threaded tubular structure.

What is claimed is:  
     
         1 . In a method of forming a sheet metal part including a nut structure by providing a sheet of metal, forming a tubular structure projecting integrally from the main body of the sheet, and tapping the tubular structure to form an internal screw thread within the tubular structure, the improvement wherein: 
 the method is carried out on a press having a plurality of spaced stations including a punch station and a working station; and    the tubular structure is formed by punching a hole in the sheet at the punch station and thereafter forming the tubular structure in surrounding relation to the hole in a single hit of the press at the working station.    
     
     
         2 . A method according to  claim 1  wherein: 
 the hole is punched in the sheet utilizing a punch and die wherein the diameter of the die is no greater than approximately five percent greater than the diameter of the punch whereby to provide a hole having a cleanly cut sidewall and thereby preclude splitting of the metal of the sheet as the tubular structure is formed at the working station.  
 
     
     
         3 . A method according to  claim 2  wherein the formation of the tubular structure at the working station comprises an extrusion step.  
     
     
         4 . A method according to  claim 3  wherein: 
 the method includes the further step of forming a coin formation at the juncture of the tubular structure and the planar main body of the sheet; and  
 the formation of the coin formation is performed in the single hit of the press at the working station.  
 
     
     
         5 . A method of forming a sheet metal part including a nut structure adapted to receive a plug having a threaded main body and an enlarged head, the method comprising: 
 providing a sheet of metal;    working the sheet to form a tubular structure projecting integrally from the planar main body of the sheet and a coin formation at the juncture of the tubular structure with the planar main body of the sheet having a diameter sized to receive the head portion of the plug; and    tapping the tubular structure to form an internal screw thread within the tubular structure, whereby the threaded main body of the plug may be threadably received in the threaded tubular structure and the head of the plug may be seated in the coin formation.    
     
     
         6 . A method according to  claim 5  wherein the working step includes an extrusion step wherein metal of the sheet is extruded into a die to form the tubular structure.  
     
     
         7 . A method according to  claim 6 , wherein, prior to the working step, a hole is punched in the sheet whereafter the working step is performed in concentric relation to the hole.  
     
     
         8 . A method according to  claim 7  wherein: 
 the hole is punched in the sheet utilizing a punch and die wherein the diameter of the die is no greater than approximately five percent greater than the diameter of the punch whereby to provide a hole having a cleanly cut sidewall and thereby preclude splitting of the metal of the sheet as the tubular structure is extruded at the working station.  
 
     
     
         9 . A method according to  claim 8  wherein: 
 the method is carried out on a press having a plurality of spaced stations including a punch station where the punching operation is performed and a working station where the working step is performed; and  
 the tubular structure is formed in a single hit of the press at the working station.  
 
     
     
         10 . A method according to  claim 9  wherein the coin formation is also formed in the single hit of the press at the working station.  
     
     
         11 . A method according to  claim 10  wherein: 
 the sheet has a starting thickness; and  
 the tubular structure has a thickness less than the starting thickness of the sheet.  
 
     
     
         12 . A method according to  claim 11  wherein the method further includes forming the planar main body of the sheet into a contoured structure in surrounding relation to the tubular structure.  
     
     
         13 . A method according to  claim 12  wherein: 
 the contoured structure comprises a dish; and  
 the tubular structure is formed proximate the bottom of the dish and projects upwardly into the hollow of the dish.  
 
     
     
         14 . A method according to  claim 11  wherein the method includes: 
 moving the sheet along a linear feed path to bring a first section of the sheet into alignment with the working station;  
 performing the working step on the first sheet section at the working station to form the tubular structure and the coin formation on the first section; and  
 thereafter moving the sheet along the feed path to bring successive sections on the sheet into alignment with the working station to allow the working step to be successively performed on the successive sections to form successive tubular structures and coin formations on the successive sections.  
 
     
     
         15 . A method according to  claim 14  wherein: 
 a tapping station is provided along the feed path downstream of the working station; and  
 each successive sheet section, following formation of the tubular structure and coin formation at the working station, is moved along the feed path to the tapping station where the tapping step is performed to provide internal screw threads on the respective tubular structure.  
 
     
     
         16 . A method according to  claim 15  wherein a punching station is provided along the feed path upstream of the working station; and 
 each successive sheet section, upon arrival at the punch station, is punched to form a hole in the sheet section whereafter the section is moved to the working station where the tubular structure and coin formation are formed in concentric relation to the respective hole.