The present disclosure relates generally to sheet metal forming tools and more particularly to manufacturing of metal-stamping dies using additive manufacturing processes.
Stamped metal parts are typically manufactured by pressing sheet metal between upper and lower machined steel dies to form a closed cavity in the net shape of a final part. Depending on part complexity, the desired net shape may be achieved in a single stage operation or through multiple stamping stages. Accordingly, a single tool having a complex profile or multiple sets of low complexity tools may alternately be used to produce the desired net shape for the stamped part. Exemplary stamping processes are disclosed in U.S. Pat. No. 2,372,516 entitled “Machine for Forming Material” which issued to Rechton et al. on Mar. 27, 1945 and U.S. Pat. No. 7,055,353 entitled “Progressive Stamping Die” which issued to Cowie on Jun. 6, 2006. These patents are incorporated by reference herein.
Typically for low volume part manufacturing, such as in prototype processing, parts are disadvantageously manufactured with multiple, low complexity tools due to the time and cost required for tool modification at each design stage. Various processes for reducing completion time for tooling have been contemplated, such as disclosed in U.S. Pat. No. 5,658,506 entitled “Methods of Making Spray Formed Rapid Tools” which issued to White et al. on Aug. 19, 1997 and U.S. Pat. No. 5,793,015 entitled “Apparatus for Rapidly Forming Laminated Dies” which issued to Walczyk on Aug. 11, 1998. While these patents provide methods for reducing cost and time for production tooling, further reductions in timing and costs need to be realized to be effective for prototype tooling.
In accordance with the present invention, a metal-stamping die or tool is provided. Another aspect, uses an additive manufacturing machine and material to create a die. A further aspect provides a method of making a die from an additive manufacturing process and/or using such a die to stamp a metal part, such as a fastener or clip.
The present apparatus and method for making a metal-stamping die is advantageous over traditional methods. For example, the present apparatus and method advantageously merges multiple die tools into a single die configuration that would otherwise be prohibitively expensive, if not impossible, to produce as a conventional die. Furthermore, reducing the number of die tools results in a savings of thousands of dollars and many weeks of die manufacturing time. In other aspects, the present method allows for quick and inexpensive design and part revisions from one manufacturing cycle to another. In yet another aspect, the present method provides a temporary tool for use while a production tool is being built or repaired. The additive manufacturing process also creates surfaces, internal voids and other die formations that would be very difficult, if not impossible, to manufacture with conventional milling machines, electrical discharge machines (EDM), and the like. Additional advantages or features of the present invention can be found in the following description and appended claims as well as in the accompanying drawings.
A metal-stamping die, in other words a die for stamping sheet metal parts, is made by an additive manufacturing process, such as three-dimensional printing (“3DP”). The die is preferably used to stamp sheet metal fasteners, such as, but not being limited to snap-in clips.
In a preferred embodiment, a part manufactured by the stamping process of the present invention is a trim fastener or clip 10, as illustrated in
Exemplary trim clip 10 has a generally U-shaped body 12 including a closed end 14, a pair of leg members 16 having an irregular polygonal configuration, and a pair of tabs 18 extending substantially perpendicular to the closed end 14. Closed end 14 includes a substantially flat lower wall 20 and a pair of parallel walls 22 extending perpendicularly to the lower wall 20. Parallel walls 22 are adjoined with leg members 16 and tabs 18 at a terminal end 24 opposite to the lower wall 20.
Each leg member 16 has a central slot 26 extending from the respective parallel wall 22 to an upper cross-member 28 arranged opposite closed end 14. Each leg member 16 extends from closed end 14 in an alternately divergent and convergent manner so as to form shoulders 30, which act as “snap-in wings” for interlocking a panel (not shown). Tabs 18 are sized to extend from the respective parallel wall 22 between respective leg members 16. In this way, leg members 16 are adjoined to parallel walls 22 at an outer periphery, while tabs 18 are adjoined centrally to parallel walls 22. Tabs 18 include a pair of protrusions 32 cut from tabs 18 (e.g., laser cut) and bent inwardly towards opposite tab 18.
A preferred manufacturing process for trim clip 10 will now be described with reference to
With reference now to
In operation, clamping blocks 56, 60 are chucked within jaws of press 48 so as to align die faces 58, 62. Laser cut blank 40 is placed on die face 62. Press 48 is then closed, so as to move upper die 52 towards lower die 54 and form a closed cavity for pressing laser cut blank 40 therebetween. This action of press 48 causes laser cut blank 40 to bend into the near-final configuration exhibited on die faces 58, 62 (e.g., first bend blank 64). In other words, flanges 44 and bridge members 46 are bent into their final configuration, but not yet bent into the final U-shape configuration.
Referring now to
In operation, second prototype tool 66 is secured within press 48 in place of first prototype tool 50 (e.g., second lower die 70 is secured at clamping block 74) so as to align die face 72 with central channel 78. First bend blank 64 is flipped and inserted between second upper die 68 and second lower die 70 so as to lie along die face 76. Press 48 is closed, so as to move second upper die 68 towards second lower die 70. Second upper die 68 is then brought into contact with first bend blank 64 at a central position, thereby causing flanges 44 and bridge members 46 to move upwardly and inwardly towards second upper die 68 (e.g., each to approximately 85° from the unbent position). In other words, flanges 44 and bridge members 46 are bent to within 10° of the final u-shape configuration (e.g., second bend blank 80).
With reference now to
In operation, third prototype tool 82 is secured within press 48 in place of second prototype tool 66. Second bend blank 80 is inserted between intermediate die 86 and third lower die 88 so as to lie within central channel 98. Press 48 is then closed, moving third upper die 84 into contact with intermediate die 86 and towards third lower die 88. Intermediate die 86 is brought into contact with second bend blank 80 at a central position, causing flanges 44 and bridge members 46 to continue inward movement to the final U-shaped configuration.
Upper die 52, lower die 54, and second lower die 70 are preferably three-dimensionally printed from a polymeric or metallic material or may alternately be formed from fused filament fabrication (FFF), selective laser sintering (SLS), electron beam melting (EBM), or direct metal laser sintered from a metallic material. The present method advantageously eliminates the traditional need for expensive progressive dies otherwise required to stamp sheet metal. A preferred 3DP machine 100 and process for forming upper die 52, lower die 54, and second lower die 70 are shown in
Machine 100 further includes at least one ink jet printer head 104, and preferably eight heads, which traverse side to side along one or more gantry rails 106 by an electric motor or other automatically controlled actuators. The gantry rail 106 also moves fore and aft above support surface 102 along outboard tracks 108, driven by an electric motor or other automatically controlled actuator. At least two storage tanks 110 or removable cartridges are connected to head 104 via supply hoses 112 in order to feed the same or different materials 114 contained within each tank 110 to multiple ink jet printer openings 116 in head 104. Openings 116 may constitute an array of 10×10 or even 100×100 nozzles, and more preferably 96 nozzles, arranged in a linear array such that multiple material flows are simultaneously emitted during a single head pass. The material is preferably an acrylic material having ultra-violet (UV) stabilizers (e.g., FULLCURE 720™ or VEROGRAY™ materials), but can alternately be a printed metallic material.
A computer controller 118, having an input keyboard 120, an output display screen 122, and a microprocessor (not shown), is connected to a central processing unit (CPU) 124 of machine 100 to control the feed of material from tanks 110 and the actuator movement of head 104 relative to support surface 102. The machine user downloads a CAD file containing design information for upper die 52 into non-transient computer memory, such as RAM, ROM, a hard drive, or removable storage, associated with computer controller 118. The user may then use software instructions stored in memory to digitally layout the desired quantity of upper dies 52 onto support surface 102. The user may also position the upper dies 52 in a manufacturing orientation; for example, by having clamping block 56 arranged to be created before more complex die face 58 or, in other words, having the die face 58 arranged in the +Z direction. Preferably, the user may indicate that the tooling (e.g., upper dies 52) be built in high quality mode with a glossy finish to provide a high resolution tool. The user also inputs the material(s) to be used in the manufacturing, whereafter the microprocessor in computer controller 118 and CPU 124 runs software to cause head 104 to begin its movement and material deposition in order to create upper dies 52.
During a first transverse pass of head 104, as shown in
As shown in
As should be understood, material 114 is deposited where computer controller 118 informs head 104 that each material formation is desired, but head 104 will not deposit any material 114 where a divet or other open area is present in the CAD drawing of the upper die 52. The material 114 is stacked in many layers, thereby creating the entire upper die 52 as an integral and single piece in a gaseous, particularly air, environment inside an enclosure of machine 100. In other words, each upper die 52 is surrounded by air on all sides, except for first layer 126, which contacts support surface 102 during the entire manufacturing cycle.
After the machine cycle is complete, the user manually removes the manufactured parts from support surface 102, such as by use of a putty knife or other removal tool. Any number of upper dies 52 can be made in a single machine cycle, which is preferably less than ninety minutes. As used herein, manufacturing or machine “cycle” refers to the time period from which head 104 begins depositing first layer 126 of material 114 until when head 104 deposits the final layer of material 114 for the completed part, inclusive of material 114 curing time. In one optional step, each upper die 52 can be further processed by dipping into a hardener, solvent, or final curing solution.
The present three-dimensional printing advantageously builds up multiple upper dies 52 and/or other tooling essentially simultaneously in the same pass, while providing the necessary detail for the die face 58 without machining. For example, all of the dies discussed herein above can be additively printed at the same time on the same 3DP machine. It is noteworthy that, due to the many ink jet printing openings 116 in head 104, each prototype tool or section thereof can be made of a different material deposited essentially simultaneously by head 104. For example, an elastomeric 3DP material can be used as a resilient, impact-absorbing layer between the more rigid stamping surface and the press, with the elastomeric and rigid layers being integrally created as a single, finished die.
Exemplary generic three-dimensional printing machines and materials that can be employed to make tools 52, 54, 70 as specified herein are disclosed in U.S. Patent Publication Nos. 2010/0217429 entitled “Rapid Production Apparatus” which published to Kritchman et al. on Aug. 26, 2010; 2011/0074065 entitled “Ribbon Liquefier for Use in Extrusion-Based Digital Manufacturing Systems” which published to Batchelder et al. on Mar. 31, 2011; and U.S. Pat. No. 7,851,122 entitled “Compositions and Methods for Use in Three Dimensional Model Printing” which issued to Napadensky on Dec. 14, 2010; U.S. Pat. No. 7,369,915 entitled “Device, System and Method for Accurate Printing of Three Dimensional Objects” which issued to Kritchman et al. on May 6, 2008; and U.S. Pat. No. 5,866,058 entitled “Method for Rapid Prototyping of Solid Models” which issued to Batchelder et al. on Feb. 2, 1999. These patent publications and patents are all incorporated by reference herein. A presently preferred machine is the Connex 500 model from Objet Geometries Inc., but may also be a Dimension Elite fused filament fabrication machine from Stratasys, Inc. Nevertheless, it should be appreciated that manufacturing the dies disclosed herein by the present three-dimensional printing steps also disclosed herein is a significant leap in technology.
In another embodiment, a direct metal laser sintering machine 200 is shown in
One suitable machine is the EOSINT M 280 Model which can be obtained from EOS GmbH of Munich. Exemplary generic machines, not known to produce any dies, are disclosed in U.S. Pat. No. 5,658,412 entitled “Method and Apparatus for Producing a Three-Dimensional Object” which issued to Retallick et al. on Aug. 19, 1997; U.S. Patent Publication No. 2009/0017219 entitled “Layer Application Device for an Electrostatic Layer Application of a Building Material in Powder Form and Device and Method for Manufacturing a Three-Dimensional Object” which published to Paasche et al. on Jan. 15, 2009; and U.S. Patent Publication No. 2009/0045553 entitled “Device and Method for a Layerwise Manufacturing of a Three-Dimensional Object from a Building Material in Powder Form” which published to Weidinger et al. on Feb. 19, 2009, all of which are incorporated by reference herein.
Referring now to
A sheet metal blank or workpiece 322 is placed between 3DP dies 302 and 304 after which clamping force is provided to close the dies and emboss an impression 324 onto workpiece 322 corresponding to formation 306 and recess 310. The 3DP tools advantageously create a very crisp and well defined embossed impression 324 due to metal bending, stretching and deformation of workpiece 322. For example, inner and outer radii R equal to half or more of the workpiece thickness, and a draw depth d of at least 1 mm, is achievable with the 3DP prototype dies. This is especially crisp in a workpiece of 0.3 mm (0.012 inch) thick. Moreover, each of the 3DP dies 302 and 304 are automatically manufactured in about 6 hours or less, which is half the time for a traditional steel die, and can be used to make at least 50 and more preferably up to 100 fastener or embossed parts. It should be appreciated that other embossed shapes may be employed, such as circles, ovals, rectangles or text.
While various embodiments have been disclosed herein, it should be appreciated that other variations may be employed. For example, tools may be manufactured having alternate die face configurations. It is also envisioned that one or more of the dies for each tool may be manufactured with the three-dimensional printing steps disclosed herein. It should also be realized that while the three step manufacturing process for the trim clip is advantageous, the trim clip may be stamped in more or less steps, although many of the present advantages may not be achieved. Additionally, entirely enclosed hollow voids can be designed and manufactured inside the clamping blocks 56, 60, 74 of the dies 52, 54, 70 in order to save material costs and weight. The number and size of these voids are die specific, in order to guarantee tool integrity. As should be understood, the tools and methods of the present disclosure can advantageously be employed in prototype processing or alternately as tools for bridging production tooling. In other words, the tools and methods of the present disclosure can be used in the interim as production tooling is being manufactured. Nevertheless, such changes, modifications or variations are not to be regarded as a departure from the spirit and scope of the invention.
This application claims the benefit and priority of U.S. Provisional Application Ser. No. 61/617,274 filed Mar. 29, 2012, which is incorporated by reference herein.
Number | Date | Country | |
---|---|---|---|
61617274 | Mar 2012 | US |