Generate stylus tool design and toolpath generation modules for 3-axis CNC manufacturing processes

Abstract

A stylus tool design and tool path generation module for a 3-axis computer numerical control manufacturing process is provided. A tool path generation method is provided whereby the tool can be any smooth, convex, axisymmetric shape. The tool comprises a tool body extending between a shank and a head. The shank is configured to be mounted in a chuck, which is optionally rotatable. In the case of the stylus tool, the head has an axisymmetric forming surface for extruding metal. In the case of a router tool, the head has a cutting face enveloped by a smooth, convex, axisymmetric surface, and the tool is used to mill a part. In at least one embodiment, the tool is a stylus tool having a forming surface generated from a portion of a clothoid curve.

Description

Technical Field

[0001] The subject matter herein generally relates to stylus tools for forming parts and toolpath generation for 3-axis computer numerically controlled (CNC) manufacturing operations. Background Art

[0002] Stylus tools are used in part manufacturing processes to form parts from metal. For example, in a progressive sheet metal forming process, the stylus tool is pressed against a metal sheet as it moves in three-dimensional space to form the part. Known stylus tools are spherical stylus tools having a hemispherical forming surface that is semicircular in cross-section. However, known stylus tools are not without disadvantages. For example, due to the high forces at the point of contact with the metal sheet and the shape of the forming surface, known stylus tools can produce a significant "cast sheet sag" (a curled area adjacent to the point of contact).

[0003] Typically, standard methods for calculating the toolpath of a stylus tool are computationally expensive and time consuming to execute. For example, a discrete Minkowski sum can be used to generate an offset surface from which the toolpath is derived, which is computationally expensive and time consuming to execute. Summary of the Invention

[0004] A stylus tool for forming a part is described. The tool includes a tool body extending between a shank and a head. The shank is configured to be coupled to a collet. The head extends between a base and a tip of the shank. The head has a forming surface between the base and the tip. The forming surface is an axisymmetric surface generated by rotating a curved profile about an axis of the stylus shank, whereby the curved profile has a curvature that increases linearly with path length from the tip.

[0005] As further described, a router tool for milling a part is provided. The tool includes a tool body extending between a shank and a head. The shank is configured to be coupled to a collet. The head extends between a base and a tip at the shank. The head has a cutting face between the base and the tip. The cutting face is enclosed by an axisymmetric surface generated by rotating a curved profile about an axis of the tool shank, whereby the curved profile has a curvature that increases linearly with path length from the tip.

[0006] As further described, a tool path generation method using a tool path generation module of a part forming machine or milling machine is provided to generate a tool path for a stylus tool or router. The tool path generation method includes inputting a part shape of a part to be formed or milled. The method inputs a tool shape of the tool based on a forming face or cutting face of the tool head between the tip and the base of the head. The tool shape from the tip to the head is generated by rotating a smooth curved profile about the axis of the tool shank, thereby generating a convex tool head.

[0007] As further described, a tool path generation method generates a tool path using a tool path generation module of a part forming machine or milling machine for forming (using a stylus tool) or milling (using a router). The tool path generation method includes inputting a part shape of a part to be manufactured. The method inputs a tool shape of a tool based on a forming surface or a cutting surface of a head of a stylus or router tool defined by a curved profile between the tip of the head and the base of the head. The curved profile is differentiable and defines a convex area. The forming surface is axisymmetric for forming a part, or the cutting surface is axisymmetric for cutting a part. The method inputs a tool size of the base of the head of the stylus tool. The method determines a tool offset surface of the part shape based on the tool shape and the tool size, and generates a tool path for forming or cutting a part based on the tool offset surface and the part shape.

[0008] As further described, a 3-axis computer numerically controlled machine tool is provided. The machine tool can be programmed for milling or forming. The machine tool includes a chuck that moves in a three-dimensional workspace via a tool locator. A controller is operatively connected to the tool locator for controlling the position of the chuck in the workspace. The controller includes a tool path generation module for generating a tool path for forming or milling a part. The tool is connected to the chuck and moves with the chuck for forming or milling a part. The tool includes a tool body extending between a shank and a head. The shank is connected to the chuck. The head extends between a base and a tip of the shank. The head has a forming face or cutting face between the base and the tip. The forming face or cutting face is axisymmetric for forming or milling a part. The forming face or cutting face is defined by a curved profile that is differentiable and defines a convex region. The tool path generation module determines a tool path for the forming or milling tool based on the tool shape of the tool defined by the forming face or cutting face.

[0009] As further described, a 3-axis computer numerically controlled machine tool is provided. The machine tool includes a chuck that moves in a three-dimensional workspace via a tool locator. A controller is operatively connected to a motor for moving the tool locator for controlling the position of the chuck in the workspace. The controller includes a tool path generation module for generating a tool path for forming or milling a part. A stylus or cutting tool is mounted in the chuck and moves with the chuck for forming or milling a part. The tool includes a tool body extending between a shank and a head. The shank is mounted in the chuck. The head extends between a base and a tip at the shank. The head has a forming surface or cutting surface between the base and the tip. The forming surface or cutting surface is axisymmetric for forming or milling a part. The forming surface or cutting surface is defined by rotating a smooth curved profile about the axis of the tool shank so that the tool head defines a convex area. The tool path generation module determines a tool path for the tool based on the tool shape of the tool defined by the forming surface or cutting surface.

[0010] As further described, the shape of the forming or cutting face of the tool is defined by rotating a parameterized definition curve so that the radius (distance from the axis of rotation) and the height (distance from the tool tip along the axis) are smooth functions about an axis of a single parameter defining a convex area. For example, an elliptical head can be defined so that the radius is given by r(t) = sin(t) and the height is given by z(t) = 2cos(t), 0 <t<pi / 2。 BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A part forming machine for forming a part by forming using a stylus tool according to an embodiment is shown.

[0012] Figure 2 A portion of a part forming machine is shown, showing a stylus tool, according to an embodiment.

[0013] Figure 3 A portion of a part forming machine is shown, showing a stylus tool, according to an embodiment.

[0014] Figure 4 Shown is a collection of stylus knives according to an embodiment.

[0015] Figure 5 A portion of a stylus tool according to an embodiment is shown.

[0016] Figure 6 A portion of a stylus tool according to an embodiment is shown.

[0017] Figure 7 Shown is a collection of stylus knives according to an embodiment.

[0018] Figure 8 A method for generating a tool path using a tool path generation module of a part forming machine is shown.

[0019] Figure 9 Shown is a model of a tool path for a part, according to an embodiment.

[0020] Figure 10 is an enlarged view of a portion of a model of a tool path for a part, according to an embodiment.

[0021] Figure 11 Shown is a model of a tool path for a part, according to an embodiment.

[0022] Figure 12 is a graph illustrating a tool offset surface determined by a tool path generation module according to an embodiment. DETAILED DESCRIPTION

[0023] Figure 1A part forming machine 100 is shown for forming a part 102 by forming using a stylus tool 200, according to an embodiment. In various embodiments, the part forming machine 100 can be an incremental sheet metal forming machine that forms the part using an incremental sheet metal forming process; however, in alternative embodiments, other types of machines using other manufacturing processes (e.g., shear spinning or milling) can be provided. The part forming machine 100 includes a controller 104 that controls the operation of the other components of the part forming machine 100. The controller 104 includes a computer 106, including a user interface 108 coupled to the computer 106. The user interface 108 includes a display 110 and a user input 112, such as a keyboard, mouse, or other user input device. The controller 104 includes a tool path generation module 120 for generating a tool path for forming the part 102 during the forming process. In various embodiments, the part forming machine can be a CNC machine. The part forming machine 100 can use a backing support or die to support the part during forming. As in two-point incremental sheet metal forming, the backing support can be a concave or convex support die. In various other embodiments, the part forming machine 100 may not use a backing support die as in single incremental sheet forming. The part forming machine may be used for double-sided incremental sheet forming using two stylus cutters 200.

[0024] The part forming machine 100 includes a chuck 150 that holds a stylus tool 200. The chuck 150 can hold the stylus tool 200 in a vertical orientation; however, in alternative embodiments, the chuck can hold the stylus tool 200 in other orientations (e.g., horizontally). The chuck 150 can be positioned above the part for forming the part from above. However, in alternative embodiments, the chuck 150 can be positioned below the part for forming the part from below. In various embodiments, the chuck 150 can be rotatable. For example, the chuck 150 can be coupled to a spindle that is rotated by a motor 152. The motor 152 is operatively coupled to the controller 104 and can be controlled based on input from the controller 104, such as controlling on / off, rotation speed, rotation direction, etc. The motor 152 can be a stepper motor, a servo motor, or another type of motor. In alternative embodiments, the stylus tool 200 is a non-rotating stylus tool. In these embodiments, the part forming machine 100 may not be provided with the motor 152. In other embodiments, the stylus tool 200 may be a cutting tool, such as a router for milling.

[0025] The part forming machine 100 includes a tool positioner 160 that is operated to move the collet 150 and the stylus tool 200 in a three-dimensional workspace for forming the part 102. In an embodiment, the tool positioner 160 includes an X positioner 162, a Y positioner 164, and a Z positioner 166. For example, the X positioner 162 can be a saddle or bracket that slides on tracks to position the motor 152 and the collet 150 in the X direction, the Y positioner 164 can be a saddle or bracket that slides on tracks to position the motor 152 and the collet 150 in the Y direction, and the Z positioner 166 can be a saddle or bracket that slides on tracks to position the motor 152 and the collet 150 in the Z direction. In alternative embodiments, other types of tool positioners 160 can be used. For example, in various other embodiments, the tool positioner 160 can be a multi-axis positioner, such as a robotic arm. The tool positioner 160 is operatively coupled to the controller 104 and may be controlled based on the tool path generated by the tool path generation module 120 .

[0026] The stylus tool 200 includes a tool body 202 extending between a shank 204 and a head 206. The shank 204 and the head 206 can be a unitary structure. The shank 204 and the head 206 extend along a tool axis 208. The shank 204 is mounted in the collet 150. The shank 204 has a shank diameter configured to be loaded into the collet 150. The head 206 extends between a base 210 and a tip 212 of the shank 204. The tip 212 is disposed at the bottom of the tool body 202 along the tool axis 208. The shaft diameter of the base 210 can be equal to the shank diameter or can be larger or smaller than the shank diameter.

[0027] The head 206 has a forming surface 220 between the base 210 and the tip 212. As the stylus tool moves along the tool path, the forming surface 220 is pressed against the sheet material to form the part. The surface 220 can be a cutting surface for cutting the part, such as in a milling process. The cutting surface is enclosed by an axisymmetric surface generated by rotating a curved profile about the axis of the tool shank. The forming surface 220 is defined by a curved profile 222. For example, the forming surface 220 is a surface of revolution generated by rotating the curved profile 222 about the axis 208. The curved profile 222 is differentiable (e.g., smooth). The curved profile 222 can be continuous. The curved profile 222 can be uninterrupted. The curved profile 222 defines a convex region of the head 206. The forming surface 220 is axisymmetric about the tool axis 208. In an embodiment, the curvature of the curved profile 222 changes linearly with the length of the curve of the curved profile 222 of the forming surface 220. The curved profile 222 may have a radius of curvature that decreases from the tip 212 to the base 210. For example, the curved profile 222 may be part of a clothoid curve. The curved profile 222 may be defined by the formula R*L=A, where R is the radius of curvature, L is the length along the length of the curve, and A is a scale factor. In various embodiments, the curved profile 222 is non-circular. For example, the curved profile 222 may be part of a rounded rectangle, or may be generated by a parabola, an ellipse, a cycloid curve, or may be defined by other non-circular shapes such as a power law curve. Some non-hemispherical tools may improve the overall geometric accuracy of the formed part. In an embodiment, the part forming machine 100 uses a stylus tool defined by a shape having a parametric profile. The part forming machine 100 is configured to use different types of stylus tools 200 having forming surfaces 220 generated from different profile curves 222 (e.g., different shapes and different sizes). The part forming machine 100 is capable of generating tool paths for various different styles of stylus tools 200. In various embodiments, the curve can be delayed from the tool axis 208, for example, include a flat surface at the tip 212, and then transition to the curved profile 222. The curved profile 222 can extend between the flat surface and the base 210.

[0028] The toolpath generation module 120 generates a toolpath for forming the part 102 using the stylus tool 200. The toolpath is based on the shape of the part 102 being formed. The toolpath is based on the size and shape of the forming surface 220 of the stylus tool 200. The size and shape of the forming surface 220 may be selected to improve the part geometry of the part 102, for example, to reduce or minimize "cast plate sink" and springback effects commonly observed in incremental sheet metal forming processes. The size and shape of the forming surface 220 may be selected based on the shape of the part 102 (e.g., the slope of the surface of the part 102, the curvature of the surface of the part 102, etc.).

[0029] The toolpath generation module 120 includes a tool shape input 122, a tool size input 124, and a part shape input 126. The toolpath generation module 120 may include other inputs, such as a tip curve delay input 130, a plate thickness input 132, a feed rate input 134, a toolpath direction input 136, a toolpath step size input 138, or other inputs. The toolpath generation module 120 determines a tool offset surface for the stylus tool 200 based on the desired part shape. The tool offset surface may be affected by the tool shape, tool size, plate thickness, etc.

[0030] The tool shape input 122 is based on the shape of the curved profile 222 used to define the forming surface 220 of the stylus tool 200. The tool shape input 122 may include a menu of different tool shapes that can be selected by the user at the user interface 108, or may include input into a text box at the user interface 108. For example, the tool shape can be selected from a list of tool shapes including those generated by rotating a portion of a circle, a portion of a clothoid, a portion of a rounded rectangle, a portion of a parabola, a portion of a power law curve, a portion of an ellipse, or other smooth curves defining a convex area. The tool path generation module 120 includes a mathematical formula associated with the tool shape for generating the tool path. The mathematical formula may be implicit, explicit, parametric, etc.

[0031] The tool size input 124 is based on the size of the forming surface 220 of the stylus tool 200. The tool size input 124 may include a menu or input box for identifying the tool size of the stylus tool 200. For example, the tool size may be based on the diameter of the stylus tool 200 (e.g., at the base 210). In various embodiments, the base 210 may be cylindrical. The base 210 may be chamfered or otherwise shaped to transition to the shank 204. The base 210 may have a different shape than the tool shape (e.g., a surface of revolution generated from a curve tangent to the profile curve at the end of the forming surface 220), thereby defining a transition region between the forming surface 220 and the shank 204. The base 210 is not used for part forming. Mathematical formulas associated with the tool shape (e.g., variables, constants, equations, etc.) affect the tool size. For a given tool shape (e.g., spherical, clothoid, etc.), the tool size affects the curvature of the curved profile 222.

[0032] Part shape input 126 is based on the geometry of part 102 being formed. Part shape input 126 may be based on design specifications for part 102. The part shape may be a digital file of an object generated by a design program (e.g., a computer-aided design (CAD) program). Part shape input 126 may include a file selection, such as a file directory or browser, to select the part shape. Part shape input 126 may include an orientation selection, such as selecting the orientation of the part (e.g., relative to a horizontal plane). The orientation selection may define the top of the part, the bottom of the part, the side of the part, etc. The orientation selection may be based on the part being formed from the inside or the outside of part 102.

[0033] The tip curve delay input 130 is based on the tip 212 having a flat surface at the tip 212. Therefore, the curved profile 222 is delayed at the tip 212. The tip curve delay input 130 can be a distance (e.g., half the width of the handle 204) that is a selection from a menu or an entry into a text box at the user interface 108.

[0034] The sheet thickness input 132 affects the tool offset determined by the tool path generation module 120 to generate the tool path. The sheet thickness input 132 can be a distance. The sheet thickness input 132 can be a selection from a menu or an entry into a text box at the user interface 108.

[0035] The feed rate input 134 can affect the forming process. The feed rate input 134 is the speed at which the tool moves along the tool path. For example, the feed rate input 134 can be expressed in mm / minute. The feed rate input 134 can be a selection from a menu or an input into a text box at the user interface 108.

[0036] The tool path generation module 120 uses the tool path direction input 136 to generate the tool path. The forming process can be a continuous process for forming the part 102. The forming process can be performed in layers. The tool path direction input 136 can define the flow of the tool path from the beginning to the end of the part forming. The tool path direction input 136 can include different types of forming paths, such as discrete (e.g., step) type forming, spiral type forming, etc. In various embodiments, the tool path direction can be changed or varied for each step to offset the torsional effect caused by the forming process. The tool path direction input 136 can be a selection from a menu or an input into a text box at the user interface 108.

[0037] The tool path step input 138 may define the distance between steps or layers of part formation. The tool path step input 138 may be a distance. The tool path step input 138 may be a selection from a menu or an entry into a text box at the user interface 108 .

[0038] Figure 2A portion of a part forming machine 100 is shown, showing a stylus tool 200 , according to an embodiment. Figure 3 A portion of a part forming machine 100 is shown, showing a stylus tool 200 , according to an embodiment. Figure 2 and Figure 3 The stylus cutters 200 shown have the same cutter shape; however, the stylus cutters 200 have different cutter sizes. Figure 3 Compared to the shaft diameter of the base 210 of the stylus tool 200 shown, Figure 2 The base 210 of the stylus tool 200 shown has a larger shaft diameter. The shank 204 of the stylus tool 200 is shaped differently to transition to the collet 150. The curved profile 222 that creates the forming surface 220 has different curve lengths between the tip 212 and the base 210. The curve length depends on the tool shape and tool size.

[0039] Figure 4 A set 201 of stylus cutters 200 according to an embodiment is shown. In the embodiment shown, the set 201 includes four stylus cutters, including a first stylus cutter 200a, a second stylus cutter 200b, a third stylus cutter 200c, and a fourth stylus cutter 200d. The stylus cutters 200a, 200b, 200c, 200d have the same tool shape; however, the stylus cutters 200 have different tool sizes. The first stylus cutter 200a has a first shaft diameter 211a of the base 210a. The second stylus cutter 200b has a second shaft diameter 211b of the base 210b. The third stylus cutter 200c has a third shaft diameter 211c of the base 210c. The fourth stylus cutter 200d has a fourth shaft diameter 211d of the base 210d. The shank 204 of each stylus cutter 200 may have the same shank diameter for use with the chuck 150 (shown in FIG. 1 ). Figure 1 The curved profiles 222a, 222b, 222c, 222d for generating the forming surface have different curve lengths 214a, 214b, 214c, 214d between the tips 212a, 212b, 212c, 212d and the bases 210a, 210b, 210c, 210d of the stylus tools 200a, 200b, 200c, 200d, respectively.

[0040] Figure 5 A portion of a stylus tool 200 according to an embodiment is shown. Figure 5The forming surface 220 of the stylus tool 200 is shown. The forming surface 220 is defined by a curved profile 222 between the tip 212 and the base 210 (shown in dashed lines) at the tool axis 208. The curved profile 222 is a generated curve that is rotated about the tool axis 208 to define the shape of the forming surface 220. In an embodiment, the forming surface 220 is non-hemispherical. In an embodiment, the curved profile 222 is defined by a parametric equation having an X parameter component (radial component) and a Y parameter component (vertical component).

[0041] In the illustrated embodiment, the curved profile 222 is defined by a clothoid curve 224. The parametric equation of the curved profile 222 is given by a Fresnel integral. The curvature of the curved profile 222 varies linearly with the length of the curve of the curved profile 222 of the forming surface 220. The curved profile 222 has a radius of curvature that decreases from the tip 212 to the base 210. For example, the radius of curvature at the tip 212 (e.g., at point 230) is greater than the radius of curvature at the end of the curved profile 222 (e.g., at point 232). In the case of a clothoid curve, the radius of curvature of the curved profile 222 at the tip 212 can be considered to be infinite (e.g., flat) at the tip 212. The forming surface 220 formed by the clothoid curve profile is flatter at the base than a hemispherical stylus tool of the same axial diameter. In an embodiment, the curved profile 222 can be defined by the formula R*L=A, where R is the radius of curvature, L is the distance along the curve of the curved profile 222 from point 230, and A is a scaling factor.

[0042] Figure 6 A portion of a stylus tool 200 according to an embodiment is shown. Figure 6 The forming surface 220 of the stylus tool 200 according to an embodiment is shown. The forming surface 220 is defined by a curved profile 222 between the tip 212 and the base 210 (shown in dashed lines). In the illustrated embodiment, the tip 212 is flat. The tip 212 includes a flat surface 226. The curved profile 222 is delayed or spaced from the tool axis 208. For example, the curved profile 222 is translated radially outward a small distance to form the flat surface 226 at the bottom of the tool. In an embodiment, the curved profile 222 is defined by a clothoid curve 224, which is used to generate the forming surface 220 (e.g., a surface of revolution about the axis 208). The curved profile 222 extends between the flat surface 226 and the base 210. The curved profile 222 has a radius of curvature that decreases from the flat surface 226 to the base 210. For example, the radius of curvature of the curved profile 222 increases from a finite value at the base 210 to become infinite at the flat surface 226.

[0043] Figure 7 A set 201p of stylus cutters 200p according to an embodiment is shown having Figure 4The stylus tools 200 shown have different tool shapes. In the embodiment shown, the forming surface 220 of the stylus tool 200p has a parabolic shape. The forming surface 220 is defined by a curved profile 222 between the tip 212 and the base 210. The set 201p includes two stylus tools having parabolic curved profiles 222 with different axial diameters at the base 210. The curved profiles 222 have different curve lengths 214 depending on the tool shape and tool size. The parabolic stylus tools 200p have different focal lengths, which define different curved profiles 222 and, therefore, different forming surfaces 220.

[0044] Figure 8 A method is shown for generating a tool path using the tool path generation module 120 of the part forming machine 100. The tool path is used to form the part 102 using a manufacturing process (e.g., forming or milling) using a stylus tool 200. The tool path generation module 120 performs the various steps identified in the flow chart to generate a tool path for forming the part.

[0045] At 600, a part shape is input into the toolpath generation module 120. The part shape is the target geometry and orientation of the part 102 to determine the shape of the part being formed. The toolpath generation module 120 may receive a set of contact points (e.g., a partial geometry or an entire geometry). The set of contact points may be on a plane corresponding to a spiral or step used to form the part. The part shape may be input by uploading or selecting a digital file of an object generated by a design program (e.g., a computer-aided design (CAD) program).

[0046] At 602, the tool shape and dimensions are input into the toolpath generation module 120. The tool shape is based on the forming surface 220 of the curved profile 222 of the stylus tool 200. The forming surface 220 is axisymmetric. The curved profile 222 of the forming surface 220 is differentiable and defines a convex region. The toolpath generation module 120 determines the sheet offset surface by offsetting the part shape normal by a specified distance. In some embodiments, such as sheet forming operations, this distance may be equal to the thickness of the blank sheet. In other embodiments, such as milling, this distance may be zero, so that no offset from the part 102 occurs. The specific stylus tool 200 used in the part forming process may be selected to improve the geometric accuracy and / or surface finish of the part 102. For example, the stylus tool may be selected to provide a tool shape that reduces or minimizes the "cast plate sink" and springback effects commonly observed in incremental sheet forming processes. The tool shape may be selected based on the shape of the part 102 (e.g., the slope of the surface of the part 102, the curvature of the surface of the part 102, etc.). The tool shape may be based on the forming surface of the stylus tool 200. The tool shape may be based on the shape of a curved profile. The tool shape may be input into the tool shape input 122 of the tool path generation module 120. The tool shape may be input by selecting a tool shape from a menu of different tool shapes, which may be selected at the user interface 108. For example, the tool shape may be selected from a list of tool shapes including a portion of a circle, a portion of a clothoid, a portion of a rounded rectangle, a portion of a parabola, a portion of a power law curve, a portion of an ellipse, or other smooth curves defining a convex region. The tool shape may be input into a text box at the user interface 108. The tool shape may be input by entering a mathematical formula associated with the tool shape into the tool shape input 122. The tool size may be based on the diameter of a portion of the stylus tool 200 (e.g., the diameter of the base 210). The tool size may be based on the diameter of the head at the uppermost boundary of the forming surface 220. The tool size may be input into the tool size input 124 of the tool path generation module 120. The tool size may be input by selecting the tool size from a menu of different tool sizes, which may be selected at the user interface 108. For example, the tool size may be selected from a list (e.g., small, medium, large) or from a drop-down menu of sizes (e.g., 10 mm, 20 mm, etc.). The tool size may be entered into a text box at the user interface 108. The tool size may affect a mathematical formula associated with the tool shape (e.g., affect a constant used within the mathematical formula).

[0047] At 610, the tool path generation module 120 picks a new contact point 410 on the offset face of the sheet. At 612, the tool path generation module 120 calculates the slope of the face at the contact point 410 in the vertical plane 412 containing the normal to the part 102. The intersection of the face and the section plane defines a part curve 414, and the calculated slope is the slope of the part curve at the point of interest.

[0048] At 614, the toolpath generation module 120 determines a point on the curved profile 222 of the stylus tool 200 that has the same slope as the part curve 414 at the contact point 410. At 616, the toolpath generation module 120 calculates a tool offset vector within the perpendicular plane 412 that corresponds to aligning the calculated point on the curved profile 222 with the current contact point 410 on the sheet offset surface. Adding the tool offset vector to the contact point 410 defines a single point on the tool offset surface. This point is offset relative to the contact point in a direction normal to the part geometry by an amount equal to the radial offset component of the corresponding point on the curved profile 222 and vertically offset by an amount equal to the vertical offset of the corresponding point on the curved profile 222. The tool offset surface is defined by the set of all points calculated in this manner from all possible contact points 410 on the surface of the part 102. Since there are an infinite number of possible contact points on the part geometry, the tool offset surface is approximated by selecting multiple contact points 410, with the surface defined by interpolation through these points. In some embodiments, the contact points can be the entire set of points in a discrete grid representation of the geometry of the formed or milled surface of part 102. In alternative embodiments, the contact points can be spaced at predetermined intervals across the part (e.g., every 0.1 mm), thereby forming a grid of contact points along the surface of part 102. A tool offset surface defines offset locations for locating a reference point for a stylus tool 200 used to form or mill part 102. The reference point for stylus tool 200 can be a fixed point on stylus tool 200, such as the tip of stylus tool 200; however, in alternative embodiments, the reference point can be at other locations. In various embodiments, such as those related to incremental sheet forming, a tool offset surface can be first determined by adding a fixed normal offset at each contact point 410 based on the initial sheet thickness of the sheet used to form the part. This initial sheet thickness offset vector is then added to the tool offset vector to define a point on the tool offset surface.

[0049] At 620, the tool path generation module 120 determines whether all selected contact points 410 have been processed. At 622, when all contact points have not been processed, the tool path generation module 120 returns to step 610 to pick new contact points. At 624, when all contact points have been analyzed, the tool path generation module 120 outputs the tool offset position for each contact point as a data set defining a tool offset surface for forming the part. At 626, the tool path generation module 120 generates a tool path by defining a path on the tool offset surface. As in the case of the spiral tool path, the tool path generated by the tool path generation module 120 can be continuous from the beginning of the process to the end of the process. In an alternative embodiment, the tool path generated by the tool path generation module 120 can be a plurality of contour paths generated by taking slices of the tool offset surface at specific values ​​of the Z coordinate to generate a Z-level tool path. In another embodiment, the tool path generated by the tool path generation module 120 can be a plurality of contour paths generated by taking slices of the tool offset surface at specific values ​​of X or Y coordinate values ​​or any linear combination of these values ​​to generate a lace (zigzag) tool path.

[0050] In various embodiments, the toolpath generation module 120 is configured to generate a toolpath from the surface of the part 102 by generating appropriate offsets with reduced 3D processing compared to conventional toolpath generation algorithms. In various embodiments, the toolpath generation module 120 can operate using assumptions to simplify the calculation of tool offset points from the target surface of the part. For example, the toolpath generation module 120 can use the assumption that the forming surface 220 of the stylus tool 200 is axisymmetric, which allows the tool offset surface for a given point to be solved in two dimensions, thereby increasing the efficiency of toolpath generation while reducing algorithmic complexity. The toolpath generation module 120 can use the assumption that the curved profile 222 is differentiable and defines a convex region in a plane. In various embodiments, the toolpath generation module 120 can generate a toolpath for a discretely defined forming surface (e.g., using a discrete set of points to define a generating curve) and / or a parameterized forming surface.

[0051] Figure 9 A model of a stylus tool, according to an embodiment, is shown positioned with respect to a part 102. Dashed line 410 shows the trajectory of the contact point. Figure 10is an enlarged view of a portion of a model of a stylus tool positioned relative to part 102, according to an embodiment. A tool path 400 is used to form part 102 using stylus tool 200. Stylus tool 200 follows tool path 400. Tool path 400 is specific to part 102 being formed. Dashed line 410 illustrates the trajectory of contact points as tool 200 follows tool path 400. The tool path is located at a tool offset plane 402 from part 102. Tool offset plane 402 can be defined relative to tip 212 of stylus tool 200. Tool offset plane 402 is based on the shape of stylus tool 200. Tool offset plane 402 is based on the slope and surface normal of the part at the contact point. Tool offset plane 402 is also based on the sheet thickness of the sheet used to form part 102. Points on tool offset plane 402 can be displaced relative to contact point 410 in the X, Y, and Z directions.

[0052] Figure 11 A model of a tool path 400 for a part 102 is shown, according to an embodiment. The tool path generation module 120 identifies a plurality of contact points 410 on the part. At each contact point 410, the tool path generation module 120 defines a vertical plane 412 containing the normal of the part 102 at the contact point 410 to define a part curve 414 of the part within the vertical plane. The tool path generation module 120 may identify a plurality of contact points along the part curve 414.

[0053] Figure 12 is a graph illustrating a tool offset surface determined by the tool path generation module 120 according to an embodiment. Figure 12 A part curve 414 and the stylus tool 200 are shown at a tool offset position for forming a part. To determine a point on the tool offset surface, the tool path generation module 120 calculates the derivative of the part curve 414 at the contact point 410. The tool path generation module 120 determines a tool contact point 420 on the profile curve 222 of the stylus tool 200 such that a corresponding point on the part curve 414 has the same derivative value as the corresponding contact point 410. The stylus tool position for forming the part 102 at the contact point 410 is at the tool offset position. The tool offset position is based on a specific tool shape and specific tool dimensions. The tool offset position can be an offset of the tool contact point 410 relative to the tip 212 and can have an X offset, a Y offset, and / or a Z offset.

[0054] It will be understood that the above description is intended to be illustrative, not restrictive. For example, the above-described embodiments (and / or aspects thereof) may be used in combination with one another. Furthermore, many modifications may be made to the teachings of this invention to adapt to specific circumstances or materials without departing from its scope. The dimensions, material types, orientations of various components, and the number and position of various components described herein are intended to define parameters of certain embodiments and are in no way limiting, but rather are merely embodiments. Numerous other embodiments and modifications within the spirit and scope of the claims will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present invention should be determined by reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms "including" and "wherein" are used as colloquial synonyms for the respective terms "comprising" and "wherein." Furthermore, in the appended claims, the terms "first," "second," and "third," etc., are used merely as labels and are not intended to impose numerical requirements on their objects. Furthermore, limitations in the appended claims are not drafted in means-plus-function format unless such limitations explicitly use the phrase "means for..." before stating a function without additional structure.

[0055] Furthermore, the present disclosure includes implementations according to the following clauses:

[0056] 1. A stylus tool for forming a part, the stylus tool comprising:

[0057] a shank configured to be coupled to the collet for positioning the stylus tool; and

[0058] A head extends between a base and a tip at the shank, the head having a forming surface between the base and the tip, the forming surface being axisymmetric and defined by rotating a curved profile about the axis of the shank, the curvature of the curved profile varying linearly with the length of the curve of the curved profile of the forming surface.

[0059] 2. The stylus tool according to clause 1, wherein the curved profile of the profiled surface is non-circular.

[0060] 3. The stylus tool according to clause 1, wherein the curved profile of the profiled surface is a portion of a clothoid curve.

[0061] 4. The stylus tool of clause 1, wherein the curved profile has a radius of curvature that decreases from the tip to the base.

[0062] 5. The stylus tool of clause 1, wherein the curved profile is defined by the equation R*L=A, where R is the radius of curvature, L is the curvilinear distance from the tip along the curved profile, and A is a scaling factor.

[0063] 6. The stylus tool of clause 1 , wherein the head comprises a flat surface at the tip, the curved profile extending between the flat surface and the base.

[0064] 7. A tool path generation method for generating a tool path using a stylus tool using a tool path generation module of a part forming machine, the tool path generation method comprising the following steps:

[0065] Input the part shape of the part to be manufactured;

[0066] inputting a tool shape of the stylus tool based on a profiled surface of the tool head defined by a curved profile between a tip of the head and a base of the head, the curvature of the curved profile varying linearly with a curve length of the curved profile of the profiled surface;

[0067] determining a tool offset surface for the part shape based on the tool shape; and

[0068] Generates toolpaths for forming the part based on tool offset faces.

[0069] 8. The tool path generation method according to clause 7, wherein the step of inputting the tool shape comprises inputting the diameter of the base into the tool path generation module.

[0070] 9. The tool path generation method according to clause 7, wherein the step of determining the tool offset surface comprises determining the tool offset surface at a plurality of contact points of the part.

[0071] 10. The tool path generation method according to clause 9, wherein the step of determining the tool offset surface comprises:

[0072] defining a vertical plane through the part at each contact point, wherein the plane also contains a normal to the part at the each contact point to define a part curve of the part within the vertical plane;

[0073] Calculating the derivative of the part curve at each contact point; and

[0074] For each contact point, a point on the curved contour of the forming surface of the generating tool having the same derivative value as that of the respective contact point is determined.

[0075] 11. The tool path generation method according to clause 10, wherein the step of generating the tool path comprises generating a tool path between designated points on a tool offset surface corresponding to desired tool contact points to form the tool path.

[0076] 12. The tool path generation method according to clause 7, wherein the step of determining the sheet offset surface includes adding a fixed offset to each contact point based on a sheet thickness of a sheet used to form the part.

[0077] 13. A tool path generation method for generating a tool path using a stylus tool using a tool path generation module of a part forming machine, the tool path generation method comprising the following steps:

[0078] Input the part shape of the part to be manufactured;

[0079] inputting a tool shape of the stylus tool based on a forming surface of the head of the stylus tool defined by a curved profile between a tip of the head and a base of the head, the curved profile being differentiable and defining a convex region, the forming surface being axisymmetric for forming the part;

[0080] Enter the tool dimensions for the base of the stylus tool head;

[0081] determining a tool offset surface for the part shape based on the tool shape and the tool size; and

[0082] Generates toolpaths for forming the part based on the tool offset faces and the part geometry.

[0083] 14. The tool path generation method according to clause 13, wherein the step of inputting the tool shape comprises inputting the tool shape from a plurality of different tool shapes.

[0084] 15. The tool path generation method according to clause 13, wherein the step of determining the tool offset surface comprises determining the tool offset surface using a plurality of contact points of the part.

[0085] 16. The tool path generation method according to clause 13, wherein the step of inputting a tool shape comprises inputting an envelope shape of the cutting tool.

[0086] 17. The tool path generation method according to clause 13, wherein the step of inputting a tool shape comprises inputting a punching tool shape.

[0087] 18. The tool path generation method according to clause 13, wherein the step of determining the sheet offset surface includes adding a fixed offset to each contact point based on a sheet thickness of a sheet used to form the part.

[0088] 19. A parts forming machine, comprising:

[0089] chuck;

[0090] a tool positioner operatively coupled to the chuck to enable movement of the chuck in a three-dimensional workspace;

[0091] a controller operatively coupled to the tool positioner for controlling the position of the cartridge in the workspace, the controller including a tool path generation module for generating a tool path for forming the part; and

[0092] A stylus tool coupled to a cartridge for forming a part, the stylus tool comprising a tool body extending between a shank and a head, the shank coupled to the cartridge, the head extending between a base at the shank and a tip, the head having a forming surface between the base and the tip, the forming surface being axisymmetric for forming the part, the forming surface being defined by a curved profile having a curvature, the curved profile being differentiable and defining a convex region,

[0093] The tool path generation module determines the tool path of the stylus tool based on the tool shape of the stylus tool defined by the forming surface.

[0094] 20. The part forming machine of clause 19, wherein the tool shape can be any one of a plurality of different tool shapes.

[0095] 21. A part forming machine according to clause 19, wherein, in addition to the tool shape of the stylus tool defined by the forming surface, the tool path generation module also determines the tool path of the stylus tool based on the tool size, which can be any one of a plurality of different tool sizes for a given tool shape.

[0096] 22. The part forming machine of clause 19, wherein the curved profile generating the forming surface is non-circular.

[0097] 23. The part forming machine of clause 19, wherein the curvature of the curved profile generating the forming surface varies linearly with the length of the curve of the curved profile generating the forming surface.

[0098] 24. The part forming machine of clause 19, wherein the curved profile generating the forming surface is a portion of a clothoid curve.

[0099] 25. The part forming machine of clause 19, wherein the head comprises a flat surface at the tip, the curved profile extending between the flat surface and the base.

[0100] 26. A parts forming machine, comprising:

[0101] chuck;

[0102] a tool positioner operatively coupled to the chuck to enable movement of the chuck in a three-dimensional workspace;

[0103] a controller operatively coupled to the tool positioner for controlling the position of the cartridge in the workspace, the controller including a tool path generation module for generating a tool path for forming the part; and

[0104] A stylus tool coupled to a collet so as to be movable through the collet for forming a part, the stylus tool comprising a tool body extending between a shank and a head, the shank coupled to the collet, the head extending between a base and a tip at the shank, the head having a forming surface between the base and the tip, the forming surface being axisymmetric for forming the part, the forming surface being defined by a curved profile having a curvature that varies linearly with a length of the curve of the curved profile of the forming surface,

[0105] The tool path generation module determines the tool path of the stylus tool based on the tool shape of the stylus tool defined by the forming surface.

[0106] 27. A part forming machine according to clause 26, wherein the tool path generation module determines the tool path of the stylus tool based on a tool size of the stylus tool defined by a diameter of the base, the tool size being any one of a plurality of different tool sizes for a given tool shape.

[0107] 28. The part forming machine of clause 26, wherein the curved profile generating the forming surface is non-circular.

[0108] 29. The part forming machine of clause 26, wherein the curved profile of the forming surface is a portion of a clothoid curve.

[0109] 30. The part forming machine of clause 26, wherein the head includes a flat surface at the tip, the curved profile extending between the flat surface and the base.

Claims

1. A stylus tool (200) for forming a part (102), the stylus tool (200) comprising: a handle (204) configured to be coupled to the chuck (150) for positioning the stylus tool (200); as well as A head (206) extending between a base (210) and a tip (212) at the shank (204), the head (206) having a shaping surface (220) between the base (210) and the tip (212), the shaping surface (220) being axisymmetric and defined by rotating a curved profile (222) about an axis (208) of the shank (204), the curvature of the curved profile (222) varying linearly with the length of the curve of the curved profile (222) of the shaping surface (220), wherein the head (206) includes a flat surface (226) at the tip (212), the curved profile (222) extending between the flat surface (226) and the base (210).

2. The stylus tool (200) according to claim 1, wherein The curved profile (222) of the forming surface (220) is non-circular.

3. The stylus tool (200) according to any one of claims 1 to 2, wherein The curved profile (222) of the shaping surface (220) is a portion (102) of a clothoid curve.

4. The stylus tool (200) according to any one of claims 1 to 2, wherein The curved profile (222) has a radius of curvature that decreases from the tip (212) to the base (210).

5. The stylus tool (200) according to any one of claims 1 to 2, wherein The curved profile (222) is defined by the equation R*L=A, where R is the radius of curvature, L is the curvilinear distance from the tip (212) along the curved profile (222), and A is a scaling factor.

6. A tool path generation method for generating a tool path using a stylus tool (200) using a tool path generation module (12) of a part forming machine (100), the tool path generation method comprising the following steps: Inputting a part shape (126) of a part (102) to be manufactured; inputting a tool shape (122) of the stylus tool based on a profiled surface (220) defined by a curved profile (222) between a tip (212) of the head and a base (210) of the head of the tool, wherein the head (206) includes a flat surface (226) at the tip (212), and the curved profile (222) extends between the flat surface (226) and the base (210); determining a tool offset surface for the part shape based on the tool shape (402); and The tool path for forming the part is generated based on the tool offset surface.

7. The tool path generation method according to claim 6, wherein: The step of inputting the tool shape includes inputting the diameter of the base into the tool path generation module.

8. The tool path generation method according to any one of claims 6 to 7, wherein: The step of determining the tool offset surface includes determining the tool offset surface at a plurality of contact points (410) of the part.

9. The tool path generation method according to claim 8, wherein: The step of determining the tool offset surface comprises: defining a vertical plane (412) through the part at each of the plurality of contact points, wherein the plane also includes a normal to the part at the each contact point to define a part curve (414) of the part within the vertical plane; calculating a derivative of the part curve at each of the plurality of contact points; and For each of the plurality of contact points, a point on the curved profile of the forming surface of the tool having the same derivative value as that of the respective contact point is determined.

10. The tool path generation method according to claim 9, wherein: The step of generating the tool path includes generating a tool path between designated points on the tool offset surface corresponding to desired tool contact points to form the tool path.

11. The tool path generation method according to any one of claims 6 to 7, wherein: The plate offset surface is determined by offsetting the part shape (126) normal by a specified distance.

12. The tool path generation method according to claim 11, wherein: The step of determining the sheet offset surface includes adding a fixed offset to each contact point based on the sheet thickness of the sheet used to form the part.

13. A part forming machine (100), comprising: Chuck (150); a tool positioner (160) operatively coupled to the chuck to move the chuck in a three-dimensional workspace; a controller (104) operatively coupled to the tool positioner for controlling the position of the chuck in the workspace, the controller including a tool path generation module for generating a tool path for forming a part; as well as The stylus tool (200) according to any one of claims 1 to 5, The tool path generation module determines the tool path of the stylus tool based on a tool shape of the stylus tool defined by the forming surface.

14. The part forming machine according to claim 13, wherein: The tool shape is any one of a plurality of different tool shapes, wherein the tool path generation module determines the tool path of the stylus tool based on a tool size (124) in addition to the tool shape of the stylus tool defined by the forming surface, the tool size being any one of a plurality of different tool sizes for a given tool shape.

15. The part forming machine according to any one of claims 13 to 14, wherein: The curved profile generating the forming surface is non-circular, wherein the curved profile generating the forming surface is a portion of a clothoid curve.

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