Patent Grant
8511172
1. Field of the Disclosure
The disclosure relates to a stretch-bend-draw bead simulator (SBDS) apparatus as well as components and methods associated therewith. The SBDS simulator can be used to experimentally evaluate pulling and holding forces of a proposed draw bead design/geometry before the proposed draw bead design is implemented in a continuous manufacturing process. Moreover, the formation of skid lines and the associated forces that cause them can be studied.
2. Brief Description of Related Technology
Sheet metal products created through the use of stamping dies sometimes feature undesirable surface distortions near regions at which the sheet metal is pulled over a tool radius. The surface distortions resulting from the pulling of the metal specimen over the tool, often referred to as “skid lines” have little significant impact on the function of the sheet metal part, but are often harmful to the manufacturer from a quality perception perspective. Currently, there exists no full, comprehensive understanding of the mechanisms which lead to surface distortions in sheet metal. Therefore, engineers have resorted to trial-and-error methods for resolving surface distortion problems during stamping die development.
The objective of the present disclosure is to provide an experimental approach for obtaining force measurements associated with pulling of sheet metal strips over a rigid tool and further understanding the mechanisms triggering surface distortions in sheet metal products.
The disclosure relates to stretch bend draw simulator (SBDS) apparatus for approximating die stamping of a metal. The apparatus generally includes: (a) a fixed base defining a longitudinal direction; (b) a mounting plate mounted to the fixed base; (c) a sheet metal drawing tool (e.g., cylindrical or rectangular shape) mounted to the mounting plate (e.g., fixedly mounted thereto), the sheet metal drawing tool having a surface for contacting a sheet metal strip when the sheet metal strip is pulled across the sheet metal drawing tool surface to provide a pulling force measurement; and (d) a draw bead block holder mounted to the mounting plate and adapted to mount a male draw bead block and a corresponding female draw bead block, wherein: (i) the draw bead block holder comprises (A) a compressing means (e.g., threaded shaft or screw press) for compressing the male and female draw bead blocks together to clamp the sheet metal strip therebetween when present, and (B) a clamping force measuring means (e.g., a load cell) for measuring a clamping force resulting from the male and female draw bead blocks clamping on the sheet metal strip when present; (ii) the draw bead block holder defines a back force direction for the sheet metal strip being clamped by the male and female draw bead blocks when present; and (iii) the draw bead block holder is positionable at a plurality of locations relative to the fixed base so that an angle θ between the longitudinal direction of the fixed base and the back force direction of the draw bead block holder can be selected to have a plurality of values (e.g., a selected value spanning 180° or ranging from −90° to +90°).
Various embodiments of the SBDS apparatus are possible. For example, the mounting plate is rotatably mounted to the fixed base so that a rotation of the mounting plate relative to the fixed base defines a desired angle θ between the longitudinal direction and the back force direction. In this case, the draw bead block holder can be fixedly mounted to the mounting plate. Additionally, the mounting plate can include one or more translation tracks and the draw bead block holder can be translatably mounted on the translation tracks so that the draw bead block holder is translatable in the back force direction to a plurality of positions on the mounting plate. In another embodiment, the mounting plate is fixedly mounted to the fixed base, and the draw bead block holder is mountable in a plurality of positions on the mounting plate, each position defining a desired angle θ between the longitudinal direction and the back force direction (e.g., the mounting plate comprises a mounting means positioned along an arc and adapted to mount the draw bead block holder at a desired position, thereby defining the desired angle θ between the longitudinal direction and the back force direction). In another embodiment, the apparatus further comprises a tool holding and moving means for removably mounting, translating, and positioning the tool with respect to the sheet metal strip; wherein: (i) the sheet metal drawing tool is mounted to the mounting plate via the tool holding and moving means for removably mounting, translating, and positioning the tool with respect to the sheet metal strip, (ii) the sheet metal drawing tool is removably mounted on the tool holding and moving means at a distal end and the tool holding and moving means is positionable from a proximal end, and (iii) the tool holding and moving means is coupled to a contact force measuring means (e.g., load cell) for measuring the contact force on the sheet metal strip with the surface of the tool. In such a case, the holding and moving means can be adapted to (i) translate the sheet metal drawing tool with respect to the sheet metal strip along a translation axis defined by the holding and moving means, and (ii) position the sheet metal drawing tool by moving the holding and moving means about a rotation axis. The tool holding and moving means can comprise a threaded shaft defining a longitudinal shaft axis, the threaded shaft being adapted to translate the tool along the longitudinal shaft axis. In another embodiment, the apparatus further comprises a base clamping means for mounting the sheet metal strip at an opposite end from the pulling end of the sheet metal strip, wherein the base clamping means is positioned adjacent the draw bead block holder and coupled to a back force measuring means (e.g., load cell) for measuring a back force resulting from holding the sheet metal strip when pulling the sheet metal strip across the sheet metal drawing tool surface. The apparatus can further comprise a male draw bead block and a corresponding female draw bead block housed within the draw bead block holder, wherein a gap or interface between adjacent surfaces of the male and female draw bead blocks defines a direction corresponding to the back force direction.
The SBDS apparatus can be included in a simulator system for approximating die stamping of a metal. The system generally includes (a) a stretch bend draw simulator apparatus according to any of its various disclosed embodiments; (b) a clamping and pulling means for securing one end of a sheet metal strip and for pulling the sheet metal strip across the sheet metal drawing tool surface of the apparatus, the clamping and pulling means having a pulling direction that defines the longitudinal direction of the fixed base; (c) optionally a pulling force measuring means for measuring a pulling force resulting from clamping and pulling the sheet metal strip across the sheet metal drawing tool surface of the apparatus; and (d) optionally a computer for obtaining and recording force data, wherein the clamping force measuring means and the pulling force measuring means are electronically coupled to the computer to transmit measured force data. In an embodiment, (i) the stretch bend draw simulator apparatus is mounted to a tensile strength measuring apparatus comprising a jaw grip and a load cell coupled to the jaw grip; (ii) the clamping and pulling means of the system comprises the jaw grip of the tensile strength measuring apparatus; and (iii) the pulling force measuring means is present and comprises the load cell of the tensile strength measuring apparatus.
The disclosure also relates to a method for simulating and measuring stretch bend draw characteristics. The method comprises: (a) providing the stretch bend draw simulator apparatus or system according to any of the various disclosed embodiments; (b) providing a male draw bead block and a corresponding female draw bead block housed within the draw bead block holder, wherein a gap or interface between adjacent surfaces of the male and female draw bead blocks defines a direction corresponding to the back force direction; (c) providing a sheet metal strip (e.g., steel, aluminum, or aluminum alloy) having first and second opposed ends; (d) clamping the sheet metal strip into the draw bead block holder between the male and female draw bead blocks at a position proximate the second end of the sheet metal strip; (e) contacting the sheet metal strip against the sheet metal drawing tool surface at a point intermediate the first and second ends of the sheet metal strip; (f) positioning the draw bead block holder at a location relative to the fixed base to select a desired angle θ between the longitudinal direction and the back force direction (e.g., wherein the longitudinal direction and the back force direction are different); and (g) pulling the sheet metal strip in the longitudinal direction across the sheet metal drawing tool surface of the apparatus from a point proximate the first end of the sheet metal strip. Pulling the sheet metal strip in part (g) can comprise securing the first end of the sheet metal strip in a clamping and pulling means and then pulling the sheet metal strip in the longitudinal direction with the clamping and pulling means. The method can further include measuring and optionally electronically communicating to a computer at least one of (i) a clamping force resulting from the male and female draw bead blocks clamping on the sheet metal strip and (ii) a pulling force resulting from clamping and pulling the sheet metal strip across the sheet metal drawing tool surface of the apparatus while pulling the sheet metal strip. Additionally or alternatively, the method can further include examining the pulled sheet metal strip for surface distortions resulting from the pulling of the across the sheet metal drawing tool surface. The method can further comprise repeating the method steps at two or more different angles θ between the longitudinal direction and the back force direction to identify an optimum angle or range of angles that reduces or eliminates surface distortions on the sheet metal strip for a selected sheet metal strip and sheet metal drawing tool.
In a particular embodiment, the SDBS apparatus comprises: (a) a tool having a surface for contacting a sheet metal strip when the sheet metal strip is clamped in a jaw grip adapted to clamp and pull one end of the sheet metal strip to provide a pulling force measurement; (b) a tool holding and moving means for removably mounting, translating, and positioning the tool with respect to the sheet metal strip, wherein (i) the tool is removably mounted on the tool holding and moving means at a distal end and the tool holding and moving means is positionable from a proximal end, and (ii) the tool holding and moving means is coupled to a contact force measuring means for measuring the contact force on the sheet metal strip with the surface of the tool; (c) a draw bead block holder adapted to mount a corresponding male draw bead block and a female draw bead block, the draw bead block holder comprising a corn pressing means for compressing the male and female draw bead blocks together to clamp the sheet metal strip and a clamping force measuring means for measuring a clamping force resulting from the male and female draw bead blocks clamping on the sheet metal strip; and (d) a base clamping means for mounting the sheet metal strip at an opposite end from the one end of the sheet metal strip, wherein the base clamping means is positioned adjacent the draw bead block holder and coupled to a back force measuring means for measuring a back force resulting from holding the sheet metal strip while the jaw grip pulls the sheet metal strip. The apparatus is adapted to analyze skid marks on the sheet metal strip resulting from contact with the tool. In an exemplary embodiment, the holding and moving means is adapted to (i) translate the tool with respect to the sheet metal strip along a translation axis defined by the holding and moving means and (ii) position the tool by moving the holding and moving means about a rotation axis. In a further exemplary embodiment, the tool holding and moving means comprises a threaded shaft defining a longitudinal axis, the shaft being adapted to translate the tool along the longitudinal axis. In yet a further exemplary embodiment, the jaw grip is coupled to a pulling force measuring means for measuring the pulling force of the jaw grip on the sheet metal strip.
The pulling force measuring means can be a tensile strength measuring apparatus coupled to a pulling force load cell. The contact force measuring means can be a contact force load cell. The clamping force measuring means can be a clamping force load cell. The back force measuring means can be a back force load cell. In a particular embodiment according to the present disclosure, each load cell is coupled to a computer for obtaining force data. The draw bead block holder is typically mounted on a mounting panel. The mounting panel is typically rotatable about a rotation point and rotates along a rotation axis. In an exemplary embodiment, the mounting panel comprises a pair of translation tracks and the draw bead block holder is translatably mounted on the translation tracks. In a further exemplary embodiment, the present disclosure provides for a simulator apparatus further comprising a translation force means for translating the draw bead block holder along a translation axis defined by tracks, wherein the translation force means is mounted on the base clamping means. The translation force means can be a threaded shaft. The compression means can also be a threaded shaft. In a particular embodiment of the present disclosure, tool defines a cylindrical or rectangular surface.
The present disclosure provides for a stretch bend draw simulator system for approximating die stamping of a metal. The system comprises: (a) a jaw grip for clamping and pulling one end of a sheet metal strip, wherein the jaw grip is coupled to a pulling force measuring means adapted to measure a pulling force resulting from the clamping of the jaw grip on the sheet metal strip; (b) a tool having a surface positioned adjacent the jaw grip to allow the sheet metal strip to contact the surface of the tool when clamped in the jaw grip, wherein the tool is (i) removably mounted in a holding and moving means for translating and/or positioning the tool with respect to the sheet metal strip, and (ii) coupled to a tool contact force measuring means adapted to measure a contact force resulting from the sheet metal strip contacting the surface of the tool; (c) a draw bead block holder mounted on a rotatable mounting panel, the draw bead block set adapted to mount a corresponding male draw bead block and a female draw bead block, the draw bead block set comprising a comprising a compressing means for compressing the male and female draw bead blocks together to clamp a sheet metal strip and a clamping force measuring means for measuring a clamping force resulting from the male and female draw bead blocks clamping on the sheet metal strip; and (d) a base clamping means for mounting the sheet metal strip at an opposite end from the one end of the sheet metal strip positioned adjacent the draw bead block set and coupled to a back force measuring means for measuring a back force resulting from holding the sheet metal strip while the jaw grip pulls the sheet metal strip. The apparatus is adapted to analyze skid marks on the sheet metal strip resulting from contact with the tool.
The present disclosure provides for a method for simulating and measuring stretch bend draw characteristics comprising the steps of: (a) clamping one end of a sheet metal strip in a jaw grip coupled to a pulling force measuring means for measuring the pulling force of the jaw grip; (b) contacting the sheet metal strip against a surface of a tool positioned adjacent the jaw grip to allow the sheet metal strip to contact the surface of the tool when clamped in the jaw grip, wherein the tool is (i) removably mounted in a holding and moving means for translating and/or positioning the tool with respect to the sheet metal strip, and (ii) coupled to a tool contact force measuring means for measuring a contact force resulting from the sheet metal strip contacting the surface of the tool; (c) clamping the sheet metal strip into a draw bead block holder comprised of a male draw bead block and a female draw bead block, wherein the draw bead block holder comprises a compressing means for compressing the male draw bead block with the female draw bead block and is clamping force measuring means adapted to measure a clamping force resulting from the male and female draw bead blocks clamping on the sheet metal strip; (d) mounting the sheet metal strip in a base clamping means for mounting the sheet metal strip at an opposite end from the one end of the sheet metal strip, wherein the base clamping means is positioned adjacent the draw bead block holder and coupled to a back force measuring means adapted to measure a back force resulting from holding the sheet metal strip while the jaw grip pulls the sheet metal strip; and (e) pulling the sheet metal with the jaw grip. In a particular embodiment, the method further comprises the steps of measuring (i) the pulling force of the jaw grip using the pulling force measuring means, (ii) the contact force resulting from the sheet metal strip contacting the surface of the tool using the contact force measuring means, (iii) the clamping force of the draw bead block holder using the clamping force measuring means, and (iv) the back force resulting from the holding of the sheet metal strip while the jaw grip pulls the sheet metal strip by using the back force measuring means. The measurements obtained from the force measuring means are communicated and stored in a computer coupled to the measuring means.
All patents, patent applications, government publications, government regulations, and literature references cited in this specification are hereby incorporated herein by reference in their entirety. In case of conflict, the present description, including definitions, will control.
Additional features of the disclosure may become apparent to those skilled in the art from a review of the following detailed description, taken in conjunction with the drawings, examples, and appended claims.
For a more complete understanding of the disclosure, reference should be made to the following detailed description and accompanying drawings wherein:
While the disclosed apparatus and methods are susceptible of embodiments in various forms, specific embodiments of the disclosure are illustrated in the drawings (and will hereafter be described) with the understanding that the disclosure is intended to be illustrative, and is not intended to limit the claims to the specific embodiments described and illustrated herein.
The disclosed stretch-bead-draw simulator (SBDS) apparatus, associated components, and associated methods are modeled and experimentally characterized as follows.
The present disclosure provides for an apparatus for measuring directly various in-plane and contact normal forces acting upon a sheet metal specimen during a stretch-bead-draw process. A SBDS 100, 200, as shown in various embodiments illustrated in
Analysis of the force data in conjunction with visual and tactile observations of the actual pulled specimens allows researchers to ascertain the conditions under which certain surface defects arise. The SBDS is a useful electro-mechanical laboratory device for improving researchers' knowledge of the physical phenomena associated with surface distortion effects in sheet metal products created in stamping dies.
Sheet metal specimens 30 that have been pulled through the exemplary SBDS apparatus have a generally curved/deformed shape as illustrated in
The draw bead block holder 10 defines a back force direction B that corresponds to the direction of the induced back force B (shown in
In the embodiment of
The wall 12 of the block holder 10 generally includes an opening 12A through which the sheet metal strip 30 can pass from the block holder 10 exterior into the cavity 14 and between a gap or interface 49 between adjacent surfaces of the male and female draw bead blocks 42, 46. Suitably, the wall includes two openings 12A on opposing walls 12 of the block holder 10 such that the metal strip 30 can be threaded through the block holder 10. When housed in the block holder 10, the gap or interface 49 defines a direction (e.g., the path therethrough taken by the strip 30) that generally corresponds to the back force direction B. Although illustrated as a slit, the opening 12A can have any convenient shape that is sized to permit pass-through of the metal strip 30 but which provides sufficient structural support to retain the draw bead block set 40 fixedly positioned relative to the block holder 10 (e.g., within the cavity 14) during a stretch-bend-draw simulation.
The SBDS apparatus in any of its variously disclosed embodiments (e.g., the apparatus 100, 200 illustrated in the figures) can be incorporated more generally into a SBDS system 300 for approximating the die stamping of a metal. In addition to the apparatus with its attendant components, the system 300 includes a clamping and pulling means 50 for securing (e.g., clamping) one end of the sheet metal strip 30 and for pulling the sheet metal strip 30 across the sheet metal drawing tool surface 27 of the apparatus. The clamping and pulling means 50 has a pulling direction P that can define the longitudinal direction L of the fixed base 110. As illustrated, the pulling direction P is vertical (e.g., aligned or substantially aligned with gravity in use, such as within about 10° or 20° from the gravity direction), but the pulling direction P more generally can be any desired direction. For example, the longitudinal direction L and the pulling direction P can be substantially parallel (e.g., as illustrated in
The SBDS apparatus and systems according to the disclosure can be used in a method for simulating and measuring stretch-bend-draw characteristics in a given experimental system, for example specified by parameters such as drawing tool shape and size, sheet metal type and thickness, draw angle. The male draw bead block 42 and the corresponding female draw bead block 46 are mounted within the draw bead block holder 10 so that the gap/interface 49 defines a direction corresponding to the back force direction B. The sheet metal strip 30 is then clamped into the draw bead block holder 10 between the male and female draw bead blocks 42, 46 at or near the distal end 30b of the sheet metal strip 30. The sheet metal strip 30 is contacted against the sheet metal drawing tool surface 27 at a point generally between the draw bead block holder 10 and the proximal end 30a of the sheet metal strip 30. The draw bead block holder 10 is then positioned at a location relative to the fixed base 110 to select a desired angle θ between the longitudinal direction L and the back force direction B. The longitudinal direction L and the back force B direction are generally different/non-parallel such that the angle θ is non-zero. The foregoing pre-simulation preparation steps generally can be performed in any desired order, after which the sheet metal strip 30 is pulled in the longitudinal direction L across the sheet metal drawing tool surface 27 from a point at or near the proximal end 30a of the sheet metal strip 30. The pulling of the sheet metal strip 30 can be performed by the securing proximal end 30a of the sheet metal strip 30 in the clamping and pulling means 50 (e.g., the jaw grip of the tensile tester) and then pulling the sheet metal strip 30 in the longitudinal direction L with the clamping and pulling means 50. Suitably, one or more of the pulling force P, the normal force N, the back force B, and the clamping force C are measured and (optionally) electronically communicated to a computer while pulling the sheet metal strip 30. Typically, a constant pulling speed is selected (e.g., for the tensile tester jaw grip or other pulling means 50) and the resulting forces are measured for a selected simulation (e.g., pulling) time. The pulling speed can be at least 20 mm/min, 50 mm/min, or 100 mm/min and/or up to 200 mm/min, 500 mm/min, 1000 mm/min, or 5000 mm/min, and the simulation/pulling time can be at least 1 sec, 2 sec, or 4 sec and/or up to 10 sec, 30 sec, or 60 sec. Once the pulling step of a simulation run is completed, the pulled sheet metal strip 30 can be examined (e.g., visual and/or tactile examination) for surface distortions resulting from the simulation, and the presence or absence of undesirable surface distortions can be correlated with any other simulation properties (e.g., measured force data profiles and/or specific geometric or physical properties).
The foregoing process for a single stretch-bend-draw simulation can be repeated for a variety of different operating conditions to identify parameters that reduce or eliminate the formation of surface distortions. For example, the process can be performed at two or more different angles θ between the longitudinal direction L and the back force direction D to identify an optimum angle or range of angles that reduces or eliminates surface distortions on the sheet metal strip 30 for a selected sheet metal strip 30 and sheet metal drawing tool 20. Additional parameters that can be varied for the determination of optimum drawing conditions can include tool 20 geometry and material selection, sheet metal strip 30 geometry and material selection, draw bead block set 40 bead/recess geometry and material selection, for example.
Because other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, the disclosure is not considered limited to the examples chosen for purposes of illustration, and covers all changes and modifications which do not constitute departures from the true spirit and scope of this disclosure.
Accordingly, the foregoing description is given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications within the scope of the disclosure may be apparent to those having ordinary skill in the art.
Throughout the specification, where the processes/methods or apparatus are described as including components, steps, or materials, it is contemplated that the compositions, processes/methods, or apparatus can also comprise, consist essentially of, or consist of, any combination of the disclosed components or materials, unless described otherwise. Numerical values and ranges can represent the value/range as stated or an approximate value/range (e.g., modified by the term “about”).
Priority is claimed to U.S. Provisional Application No. 61/336,753, filed Jan. 26, 2010, the disclosure of which is incorporated herein in its entirety.
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| Number | Date | Country | |
|---|---|---|---|
| 20110271775 A1 | Nov 2011 | US |
| Number | Date | Country | |
|---|---|---|---|
| 61336753 | Jan 2010 | US |
