Method of reducing tool marks in incremental forming

Abstract

Methods of reducing tool marks in incremental forming are disclosed. The disclosure provides a method of incrementally forming a workpiece. In one form, the method includes securing a sacrificial material layer to at least one surface of the workpiece, directly applying a force to the sacrificial material layer by at least one forming tool, and incrementally forming the workpiece into a desired geometry based on a tool path of the forming tool.

Description

Technical Field

[0001] This disclosure relates to a method for reducing tool marks when incrementally forming workpieces. Background Technology

[0002] The descriptions in this section provide only background information in connection with this disclosure and do not constitute prior art.

[0003] Incremental forming is a manufacturing technique used to form a workpiece without the need for an associated forming die. Typically, the workpiece is incrementally formed by two opposing forming tools, as described in, for example, U.S. Patents Nos. 8,302,442, 8,322,176, 8,733,143, and 8,783,078, which are commonly assigned to this application and whose contents are incorporated herein by reference in their entirety.

[0004] The forming tool often leaves hard marks along the surface of the workpiece being formed, which can lead to insufficient surface quality. This disclosure solves the surface quality problem in incremental forming. Summary of the Invention

[0005] A method for incrementally forming a workpiece is provided, comprising: securing a sacrificial material layer to at least one surface of the workpiece; applying force directly to the sacrificial material layer using at least one forming tool; and incrementally forming the workpiece to a desired geometry based on a toolpath of the forming tool. In another embodiment, the method further comprises: securing another sacrificial material layer to an opposing surface of the workpiece; and applying force directly to the sacrificial material layer and the other sacrificial material layer using opposing forming tools. In another variation, the method further comprises: securing an elastic material to the at least one surface of the workpiece; and securing the sacrificial material layer to the elastic material. In one embodiment, the method comprises: securing the sacrificial material layer around the periphery of the workpiece, and, with the additional sacrificial material layer and elastic material, all materials are secured around the periphery of the workpiece. This disclosure also includes adding a lubricant to the outer surface of the sacrificial material layer.

[0006] In one embodiment, the sacrificial material layer is a metal sheet. The metal sheet may be low-carbon steel with a thickness between about 0.1 mm and about 1.0 mm, and in another embodiment, the sacrificial material layer is a protective film. In yet another embodiment, an adhesive layer is applied between the protective film and the workpiece. This disclosure also includes workpieces formed according to the various methods disclosed herein.

[0007] According to the teachings of this disclosure, another method for incrementally forming a workpiece is also provided. This method includes: securing a first elastic material to a surface of the workpiece, securing a first sacrificial material layer to the first elastic material, securing a second elastic material to an opposite surface of the workpiece, securing a second sacrificial material layer to the second elastic material, and incrementally forming the workpiece by applying force directly to the sacrificial material layer. In a variation of this method, the sacrificial material layer is secured around the periphery of the workpiece, while in another variation, the elastic material is also secured around the periphery of the workpiece. A lubricant may be applied to at least one outer surface of the sacrificial material layer. In one embodiment, the sacrificial material layers are all sheet metal, and in a variation, they are low-carbon steel with a thickness between about 0.1 mm and about 1.0 mm. Workpieces formed according to these methods are also provided by the teachings of this disclosure.

[0008] In another embodiment, an apparatus for incrementally forming a workpiece is provided. The apparatus includes a frame and at least one sacrificial material layer, the frame being configured to receive the workpiece, the at least one sacrificial material layer being fixed to the frame and configured to conform to a working surface of the workpiece. In a variation of this apparatus, another sacrificial material layer is fixed to the frame and configured to conform to an opposing working surface of the workpiece, wherein a space for receiving the workpiece is formed between the sacrificial material layers. At least one resilient material may be disposed between the workpiece and the sacrificial material layers. In another variation, the sacrificial material layer is a metal sheet, and the metal sheet may be low-carbon steel with a thickness between approximately 0.1 mm and approximately 1.0 mm.

[0009] Other applicable areas will become apparent from the description provided herein. It should be understood that the descriptions and specific examples are intended for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0010] To better understand this disclosure, it will now be described in various forms by way of example, with reference to the accompanying drawings, wherein:

[0011] Figure 1 It is a side cross-sectional view of the workpiece and various sacrificial and elastic materials positioned before incremental forming;

[0012] Figure 2 yes Figure 1 The workpiece and material are being incrementally formed in the side cross-sectional view;

[0013] Figure 3 From Figure 1 Detail 3-3 is a detailed view showing an exemplary material layer used in incremental forming of a workpiece;

[0014] Figure 4 These are photographs of workpieces with hard tool marks, based on existing technology;

[0015] Figure 5 A flowchart is shown of a method for incrementally forming a workpiece according to the teachings of this disclosure;

[0016] Figure 6 A flowchart of another method for incrementally forming a workpiece according to the teachings of this disclosure is shown.

[0017] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure in any way. Detailed Implementation

[0018] The following description is exemplary in nature and is not intended to limit the scope of this disclosure, its application, or its use. It should be understood that throughout the drawings, corresponding reference numerals denote similar or corresponding parts and features.

[0019] Reference Figure 1 and Figure 2 A system for incremental forming of a workpiece is shown and is generally indicated by reference numeral 10. The workpiece 12 may be made of any suitable material or a combination of materials (such as metals, metal alloys, polymeric materials, or combinations thereof) having desired forming properties. In at least one form, the workpiece 12 is a sheet metal. The workpiece 12 has at least one surface 14 and may be configured with an initial shape that is generally planar or, in one or more forms of this disclosure, at least partially pre-formed into a non-planar geometry.

[0020] Generally, in incremental forming, workpiece 12 is shaped into a desired configuration through a series of small incremental deformations. These small incremental deformations can be provided by moving one or more tools 32 and 32' along and against one or more surfaces 14 of workpiece 12. The movement of the tools can occur along a predetermined or programmed path. Furthermore, the tool movement path can be adaptively programmed in real time based on measured feedback (such as from sensors, for example, force sensors). Thus, incremental forming can occur incrementally as at least one tool (e.g., 32, 32') moves without removing material from workpiece 12. Further details of this system 10 are described in U.S. Patents Nos. 8,302,442, 8,322,176, 8,733,143, and 8,783,078, which are incorporated herein by reference in their entirety.

[0021] System 10 may include multiple components to facilitate the forming of workpiece 12, such as frame 20, multiple clamps 30 configured to surround the periphery of workpiece 12, forming tools 32 and 32', at least one sacrificial material layer 70 and optionally at least one elastic material 72 and other layers, as described in more detail below. Throughout this specification, forming tools 32 and 32' should be construed as generally synonymous with the first forming tool and the second forming tool.

[0022] The frame 20 and the clamp 30 are configured to support the workpiece 12. The frame 20 is constructed to at least partially define an opening in which the workpiece 12 is placed (partially shown in...). Figure 1 The "graphic frame" of the (in the middle). When the workpiece 12 is mounted in the frame 20 and fixed by the clamp 30, the workpiece 12 is positioned in the opening or at least partially covers the opening.

[0023] The fixture 30 is configured to engage the workpiece 12 and apply a clamping or holding force to it, such that the periphery of the workpiece 12 remains stationary during incremental forming. The fixture 30 may be disposed along multiple sides of the frame 20 and may have any suitable configuration and associated geometry for keeping the workpiece 12 stationary. For example, the fixture 30 may be manually, pneumatically, hydraulically, and / or electrically actuated. Furthermore, the fixture 30 may be configured to provide a fixed or adjustable amount of force on the workpiece 12. In another embodiment, mechanical fasteners (not shown) may be used instead of the fixture 30 and other means for securing the workpiece 12 during incremental forming.

[0024] The first forming tool 32 and the second forming tool 32' have multiple degrees of freedom and are positioned according to the design specifications of the workpiece 12. The forming tools 32, 32' are configured to move along multiple axes (such as axes extending in different orthogonal directions like the X, Y, and Z axes). Note that the forming tools 32, 32' can be positioned according to coordinate systems including Cartesian coordinates (X, Y, Z), cylindrical coordinates (ρ, ρ...). z) and spherical coordinate system (ρ, θ, ... The forming tool 32, 32' can be positioned in any coordinate system. In one or more forms of this disclosure, the forming tool 32, 32' may be disposed on the spindle and configured to rotate about an associated axis of rotation.

[0025] Forming tools 32, 32' apply force to incrementally form workpiece 12 without removing material. Forming tools 32, 32' can have any suitable geometry, including but not limited to planar, curved, spherical, conical, or combinations thereof. For simplicity, a spherical tool is depicted in the accompanying drawings and context. Figure 4As shown, when forming tools 32 and 32' incrementally form workpiece 12, tool marks are sometimes left on the surface of workpiece 12. These tool marks may be unacceptable when the part has specific surface finish requirements and / or tight tolerances for its contour. Therefore, this disclosure addresses this problem as described in more detail below.

[0026] like Figures 1 to 3 As shown, the sacrificial layer 70 is configured to reduce tooling marks from the incremental forming process. In one embodiment, the sacrificial layer 70 is attached to at least one surface of the workpiece 12, and at least one of the forming tools 32, 32' applies force directly to the sacrificial layer 70 rather than directly to the workpiece 12. During the incremental forming process, the applied force is transmitted to the workpiece 12 through the sacrificial layer 70. Therefore, any tooling marks from the forming tools 32, 32' are mostly generated on the sacrificial layer 70 rather than on the workpiece 12. As a result, the formed workpiece 12 has an improved surface quality more suitable for a particular application.

[0027] The sacrificial layer 70 should have a low coefficient of friction to reduce friction between the forming tools 32, 32' and the sacrificial layer 70. The sacrificial layer 70 should have sufficient rigidity and stiffness to resist buckling caused by friction. Since it is difficult to obtain the desired combination of properties from only one sacrificial layer 70, more than one sacrificial layer 70 may be included, as described in more detail below. The sacrificial layer 70 is called "sacrificial" because it is not included in the formed workpiece 12 and is discarded or recycled after the workpiece 12 is formed. If recycled, the sacrificial layer 70 can be reused multiple times to incrementally form more than one workpiece 12, depending on the stringency of the incremental forming process forming the given workpiece 12. The sacrificial layer 70 has sufficient thickness to redistribute force or pressure to the workpiece 12. However, as the thickness of the sacrificial layer 70 increases, the level of protection for the workpiece 12 increases, while forming becomes more difficult and less precise.

[0028] In various forms, the sacrificial layer 70 fixes at least one surface 14 of the workpiece 12, multiple sacrificial layers 70 are fixed to at least one surface 14 of the workpiece 12, and multiple sacrificial layers 70 are fixed to opposite sides of the workpiece 12, wherein the sacrificial layers 70 among the multiple sacrificial layers 70 may have different thicknesses and may be made of different materials. For example, in one form, for a workpiece 12 with a thickness between 0.5 mm and 4 mm, the sacrificial layer 70 is low-carbon steel with a thickness between 0.1 mm and 1.0 mm.

[0029] In such Figure 3In one of the best variations shown, a first elastic material 72 is fixed to the surface 14 of the workpiece 12, a first sacrificial material layer (e.g., 70) is fixed to the first elastic material 70, a second elastic material 72' is fixed to the opposite surface 14' of the workpiece 12, and a second sacrificial material layer 70' is fixed to the second elastic material 72'.

[0030] The elastic materials 72 and 72' are similarly operable to transfer force from the forming tools 32, 32' through the first sacrificial material layer 70 and the second sacrificial material layer 70' to the workpiece 12. The elastic material 72 is fixed to at least one surface of the workpiece 12, therefore the description of the second elastic material 72' is merely exemplary. Similarly, while remaining within the scope of this disclosure, the sacrificial layer 70 and the elastic material 72 may be used only on one side of the workpiece 12. Furthermore, it should be understood that, while remaining within the scope of this disclosure, any number of materials and layers may be used depending on the material and geometry of the specific workpiece 12 being incrementally formed.

[0031] Because forming tools 32, 32' apply force to sacrificial layers 70 / 70' and elastic materials 72 / 72', the formed workpiece 12 has an improved surface quality more suitable for a specific application. Since obtaining the desired combination of properties from a single elastic material 72 can be difficult, the elastic material 72 may comprise more than one layer. The elastic material 72 should be compressible and have a Young's modulus sufficient to redistribute compressive forces and associated contact pressures over a larger area. The elastic material 72 has sufficient thickness to redistribute forces or pressures from forming tools 32 and 32' to the workpiece 12. However, as the thickness of the elastic material 72 increases, the level of protection for the workpiece 12 increases, but forming becomes more difficult and less precise. In various forms, the elastic material 72 is fixed to at least one surface of the workpiece, multiple elastic materials 72 are fixed to at least one surface of the workpiece, and multiple elastic materials 72 / 72' are fixed to two opposite surfaces of the workpiece, wherein the elastic materials 72 may have different thicknesses, and the multiple elastic materials may be different materials. For example, in one form, the elastic material 72 is a rubber with a thickness between about 0.2 mm and about 5 mm.

[0032] Lubricants can be applied to workpiece 12, forming tools 32 and 32', sacrificial layer 70, and elastic material 72, and combinations thereof, to improve slippage, reduce friction, and lower shear stress, among other benefits. Therefore, lubricants are applied to improve the incremental forming of workpiece 12 and the surface quality of workpiece 12.

[0033] In another form, a polymeric material may be used as the sacrificial layer 70; in yet another form, a protective film is the sacrificial layer 70. Furthermore, an adhesive (not shown) may be applied to the workpiece 12, the sacrificial layer 70, or the elastic material 72 to prevent slippage / movement between the workpiece 12, the sacrificial layer 70, and / or the elastic material 72. In one form, the adhesive is a low-tack pressure-sensitive adhesive.

[0034] Reference Figure 5 A method for incrementally forming a workpiece is illustrated and is generally indicated by reference numeral 100. At step 102, the method includes attaching a sacrificial material layer to at least one surface of the workpiece. At step 104, force is applied directly to the sacrificial material layer via at least one forming tool. The applied force is transmitted through the sacrificial material layer and applied to the workpiece. Tool marks from the forming tool are applied to the sacrificial layer, not the workpiece. At step 106, based on the tool path of the forming tool, the workpiece is incrementally formed into a desired geometry.

[0035] Reference Figure 6 Another method for incrementally forming a workpiece is illustrated and is generally indicated by reference numeral 110. At step 112, the method includes securing a first elastic material to the surface of the workpiece, and then, in step 114, securing a first sacrificial material layer to the first elastic material. Next, in step 116, securing a second elastic material to the opposite surface of the workpiece, and then, in step 118, securing a second sacrificial material layer to the second elastic material. In step 120, the workpiece is incrementally formed by applying force directly to the sacrificial material layer.

[0036] These methods can be implemented in any order of steps, and are not limited to the methods shown herein. Furthermore, using references... Figures 1 to 3 The method is carried out using a variety of materials and components as described herein (e.g., sacrificial material layers, elastic materials, lubricants, adhesives). Different combinations of these materials and components, the materials used in their construction, the order of their arrangement on the workpiece 12, the method steps for incrementally forming the workpiece 12, and other features should be interpreted within the scope of this disclosure.

[0037] The description in this disclosure is exemplary in nature only, and therefore, variations without departing from the spirit and scope of this disclosure are intended to be within its scope. Such variations are not considered to depart from the spirit and scope of this disclosure.

Claims

1. A method for incremental forming of more than one workpiece, comprising: The first elastic material is fixed to at least one surface of the first workpiece; A sacrificial material layer is fixed to the first elastic material, the sacrificial material layer comprising a metal plate; A first force is applied directly to the sacrificial material layer using a forming tool to incrementally shape the first workpiece into the desired geometry based on the tool path of the forming tool; Remove the sacrificial material layer from the first elastic material; The second elastic material is fixed to at least one surface of the second workpiece; The sacrificial material layer is fixed to the second elastic material; as well as The second force is applied directly to the sacrificial material layer using the forming tool to incrementally shape the second workpiece into another desired geometry based on another tool path of the forming tool.

2. The method according to claim 1, wherein, Each of the first elastic material and the second elastic material is rubber with a thickness between 0.2 mm and 5 mm.

3. The method according to claim 1, wherein, When the sacrificial material layer and the first elastic material are fixed to at least one surface of the first workpiece, the sacrificial material layer and the first elastic material are fixed around the periphery of the first workpiece, and When the sacrificial material layer and the second elastic material are fixed to at least one surface of the second workpiece, the sacrificial material layer and the second elastic material are fixed around the periphery of the second workpiece.

4. The method according to any one of claims 1 to 3, further comprising: Lubricant is applied to the outer surface of the sacrificial material layer.

5. The method according to claim 1, wherein, The metal plate is low-carbon steel with a thickness between 0.1 mm and 1.0 mm.

6. The method according to claim 1, wherein, The sacrificial material layer also includes a protective film.

7. The method according to claim 1, further comprising: An adhesive layer is applied between the sacrificial material layer and the first workpiece; as well as An adhesive layer is applied between the sacrificial material layer and the second workpiece.

8. A workpiece formed by the method according to claim 1.

9. An apparatus for incremental forming of more than one workpiece, comprising: The frame is configured to receive the workpiece; The fixture is configured to hold the workpiece to the frame; An elastic material is fixed to the frame and configured to be fixed to at least one surface of the workpiece; A sacrificial material layer, fixed to the frame and configured to be fixed to the resilient material, the sacrificial material layer comprising a metal plate; A forming tool is configured to apply force directly to the sacrificial material layer when the sacrificial material layer, the elastic material, and the workpiece are fixed to the frame, to incrementally shape the workpiece into a desired geometry based on the toolpath of the forming tool. The frame, the fixture, the sacrificial material layer, and the forming tool are configured to cooperate such that: when the sacrificial material layer is fixed to an elastic material fixed to at least one surface of a first workpiece, the forming tool applies a first force directly to the sacrificial material layer to incrementally shape the first workpiece into a desired geometry based on a tool path of the forming tool; the sacrificial material layer is configured to be removed from the elastic material and fixed to an elastic material fixed to at least one surface of a second workpiece; when the sacrificial material layer is fixed to the elastic material fixed to at least one surface of the second workpiece, the forming tool applies a second force directly to the sacrificial material layer to incrementally shape the second workpiece into another desired geometry based on another tool path of the forming tool.

10. The apparatus according to claim 9, wherein, The metal plate is low-carbon steel with a thickness between 0.1 mm and 1.0 mm.

11. The apparatus according to claim 9, wherein, The elastic material is rubber with a thickness between 0.2 mm and 5 mm.

12. The apparatus according to claim 9, further comprising: A lubricant is applied to the outer surface of the sacrificial material layer.

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