Slope-matched stylus tool for incremental sheet forming

Abstract

A slope-matched stylus (SMS) tool for Incremental Sheet Forming (ISF) of a sheet includes a shaft connected to a stylus body and to a multi-axis drive mechanism. The stylus body has a conical or generally frustoconical form which includes a tool surface defining one or more corresponding tool wall angles. The tool wall angle range matches one or more part wall angles of a part formed via the ISF process, such that a flat line of contact exists between the stylus body and sheet. The tool and part wall angles are complementary. A system includes the tool and drive mechanism. A method includes securing the sheet to a fixture, connecting the tool to the drive mechanism, and progressively pressing a tool surface of the stylus body into or against the sheet using the drive mechanism, controlling the latter to ensure a flat line of contact is provided between the stylus body and sheet.

What is claimed is: 
     
         1 . A slope-matched stylus (SMS) tool for an Incremental Sheet Forming (ISF) process in which a three-dimensional (3D) part is progressively fabricated from a sheet, the SMS tool comprising:
 a shaft having a longitudinal axis, a first distal end, and a second distal end, wherein the first distal end of the shaft is configured to connect to a multi-axis drive mechanism; and   a stylus body connected to the second distal end of the shaft, wherein the stylus body has at least one tool surface defining, relative to the longitudinal axis of the shaft, a corresponding tool wall angle that matches a part wall angle of the 3D part such that the corresponding tool wall angle and the part wall angle form complemementary angles, and wherein a flat line of contact is present between the stylus body and a working surface of the sheet during the ISF process.   
     
     
         2 . The SMS tool of  claim 1 , wherein the stylus body is conical, and includes a base surface connected to the second distal end of the shaft, and a side wall extending axially from the base surface toward a rounded tip of the stylus body, and wherein the at least one tool surface defines the corresponding tool wall angle. 
     
     
         3 . The SMS tool of  claim 2 , wherein the corresponding tool wall angle includes a single tool wall angle of less than about 20°. 
     
     
         4 . The SMS tool of  claim 1 , wherein a non-linear relationship exists between the corresponding tool wall angle and a sweep angle of the SMS tool. 
     
     
         5 . The SMS tool of  claim 1 , wherein the corresponding tool wall angle includes a relatively shallow tool wall angle in a range of about 5° to about 20°, and a relatively steep tool wall angle in a range of about 55° to about 70°, such that the stylus body is configured to form the 3D part with a part wall angle varying anywhere within a range of about 5° to about 70°. 
     
     
         6 . The SMS tool of  claim 5 , wherein the relatively shallow tool wall angle is about 10° and the relatively steep tool wall angle is about 60°. 
     
     
         7 . The SMS tool of  claim 1 , wherein the at least one tool surface is a planar tool surface arranged orthogonal to the longitudinal axis of the shaft, the multi-axis drive mechanism is a 5-axis drive mechanism, and the longditudinal axis of the shaft is aligned normal to the working surface of the 3D part at the line or plane of contact by operation of the 5-axis drive mechanism. 
     
     
         8 . A system for use in an Incremental Sheet Forming (ISF) process during which a three-dimensional (3D) part is progressively fabricated from a sheet, the system comprising:
 a multi-axis drive mechanism; and   a slope-matched stylus (SMS) tool, including:
 a shaft having a longitudinal axis, a first distal end connected to the multi-axis drive mechanism, and a second distal end; and 
 a stylus body connected to the second distal end of the shaft, wherein the stylus body includes at least one tool surface defining, relative to the longitudinal axis of the shaft, a corresponding tool wall angle that matches a part wall angle of the 3D part such that the corresponding tool wall angle and the part wall angle form complemementary angles, and wherein a flat line of contact is provided between the stylus body and a working surface of the sheet during the ISF process. 
   
     
     
         9 . The system of  claim 8 , wherein the stylus body is conical and includes a base surface connected to the second distal end of the shaft, and a side wall extending axially from the base surface toward a rounded tip of the stylus body, and wherein the at least one tool surface defines the corresponding tool wall angle. 
     
     
         10 . The system of  claim 9 , wherein the corresponding tool wall angle includes a single slope of less than about 20°. 
     
     
         11 . The system of  claim 9 , wherein the 3D part defines multiple different part wall angles, the corresponding tool wall angle includes multiple corresponding tool wall angles defining a sweep angle range, and the multiple corresponding tool wall angles form a subset of the sweep angle range, and wherein the multi-axis drive mechanism is a 4-axis drive mechanism. 
     
     
         12 . The system of  claim 11 , wherein the sweep angle range has a minimum tool wall angle in a range of about 5° to 20°, and a maximum tool wall angle in a range of about 55° to 70°. 
     
     
         13 . The system of  claim 12 , wherein the minimum tool wall angle is about 10° and the maximum tool wall angle is about 60°. 
     
     
         14 . The system of  claim 8 , wherein the multi-axis drive mechanism includes a CNC machine. 
     
     
         15 . The system of  claim 8 , wherein the at least one tool surface is a planar tool surface arranged orthogonal to the longitudinal axis of the shaft, the multi-axis drive mechanism is a 5-axis drive mechanism, and the longitudinal axis of the shaft is aligned approximately normal to the working surface of the 3D part at the line or plane of contact by the 5-axis drive mechanism during the ISF process. 
     
     
         16 . An Incremental Sheet Forming (ISF) method during which a three-dimensional (3D) part is progressively fabricated from a sheet, comprising:
 securing the sheet to a fixture;   connecting a first distal end of a shaft of a slope-matched stylus (SMS) tool to a multi-axis drive mechanism, the SMS tool having a stylus body connected to a second distal end of the shaft, wherein a tool surface of the SMS tool has a corresponding tool wall angle of less than about 20° that matches a part wall angle of the 3D part such that the corresponding tool wall angle and the part wall angle form complemementary angles, and such that a flat line of contact is provided between the stylus body and the sheet; and   progressively pressing a tool surface of the stylus body into or against the sheet using the multi-axis drive mechanism to thereby form the 3D part.   
     
     
         17 . The method of  claim 16 , wherein the corresponding tool wall angle is a single tool wall angle of less than about 20°, and progressively pressing the working surface of the stylus body into or against the sheet includes using a 3-axis CNC machine as the multi-axis drive mechanism to control translation of the SMS tool in a three-dimensional space. 
     
     
         18 . The method of  claim 16 , wherein the 3D part has multiple different part wall angles, the stylus body defines a sweep angle range inclusive of multiple corresponding tool wall angles, and progressively pressing the working surface of the stylus body into or against the sheet includes using a 4-axis drive mechanism as the multi-axis drive mechanism to control translation of the SMS tool in the three-dimensional space and rotation of the SMS tool about a longitudinal axis of the shaft, to match the tool wall angle to one of the multiple different part wall angles. 
     
     
         19 . The method of  claim 16 , wherein the working surface of the stylus body is arranged orthogonally with respect to the longitudinal axis of the shaft, the multi-axis drive mechanism is a 5-axis drive mechanism, and the pressing the working surface of the stylus body into or against the sheet includes using a 5-axis drive mechanism to align the longitudinal axis of the tool shaft approximately normal to the surface of the 3D part along the flat line or plane of contact to maintain alignment of the planar bottom tool surface with a local tangent plane of the 3D part. 
     
     
         20 . The ISF method of  claim 16 , wherein the SMS tool has a sweep range having a shallow tool wall angle in the range of about 5-25 degrees and a steep tool wall angle in the range of about 70-90 degrees, and progressively pressing the tool surface of the stylus body into or against the sheet includes progressively pressing the tool into or against the sheet.