WO2006085858A2

WO2006085858A2 - Flanged sheet material staking apparatus and method

Info

Publication number: WO2006085858A2
Application number: PCT/US2005/003651
Authority: WO
Inventors: Jonathon R. Campian
Original assignee: Modern Body Engineering Corp.
Priority date: 2005-02-07
Filing date: 2005-02-07
Publication date: 2006-08-17
Also published as: WO2006085858A3

Abstract

An apparatus and method is described to join a flange (F) on a periphery of a sheet material (A) supported in a nest (30). The apparatus includes an end effector (50) located on the end of a robotic arm (42). The end effector includes a hub (52) slidably supported in a cylinder (56). At least one forming stake (70) is located on an extension (68) from the hub. A biasing element (58) interposed between the cylinder and the hub enables precise control of the staking force by maintaining a relative relationship between the end of the robotic arm and the nest.

Description

FLANGED SHEET MATERIAL STAKING APPARATUS AND METHOD

FIELD OF THE INVENTION

[0001] The present invention relates to systems that form and join sheet material. More particularly, the present invention describes a tool and method of use in staking a flange on a first panel to capture an edge on a second panel.

DESCRIPTION OF THE RELEVANT ART [0002] One of the earliest operations required in the history of automobile assembly was the joining of an inner panel to an outer panel to form any of a variety of body parts, including doors, engine hoods, fuel tank doors and trunk lids, all referred to as "swing panels" which enclose the vehicle frame. One type of joining method includes forming a flange of the outer panel over an edge of the inner panel to form a joint therebetween. Such an operation may be accomplished with the use of a roller tool performing multiple rolling passes or nudges to push the flange over from a generally upright configuration to a folded configuration or seam. Another known method to form a flange is to use a forming steel selectively positioned by a linear slide mechanism to move the forming steel in a direction normal to the flange to be formed. [0003] It is often desirable to utilize an adhesive in the joint formed by the flange to further secure the panel assembly together. While rapid curing adhesives are generally known and used in this application, a certain amount of curing time is required before the panel assembly can be moved out of the panel assembly cell without the two panels sliding out of joined alignment. The end result being that the curing time in the assembly cell can limit the production capacity of a given cell.

[0004] Certain efforts have been made to reduce this idle time. One such effort is the use of an adhesive formulation that includes rigid beads within the mastic. The beads are intended to provide discrete clamping elements that are captured between the flange, thereby locally exerting a clamping pressure between the outer and inner panel. Such an adhesive formulation has proven to work to some degree of satisfaction; however not without drawbacks. Specifically, adhesive formulations of this nature tend to be more costly than formulations without rigid beads. In addition, specialized equipment for dispensing the adhesive may be required. Moreover, local spring back along the length of the flange generally yield little or no clamping pressure. [0005] Another such effort is to draw dimples about the pre-flanged areas of the outer panel during the preliminary draw die stamping. A secondary stamping operation flanges the panel periphery along with the dimples. Later, during the hemming operation, the flanges are hemmed over with the dimples, creating a point of high contact compression at each dimple. Such dimples have proven to work to some degree of satisfaction; however not without drawbacks. Draw die maintenance becomes problematic as the small form that makes the dimple wears at a rapid rate yielding inconsistent dimple height. Also, spring back reduces the dimple contact compression yielding little or no clamping pressure. [0006] Accordingly, prior approaches to address flanged sheet material forming and joining have failed to overcome all the aforementioned problems.

SUMMARY OF THE PRESENT INVENTION

[0007] It is thus a general object of the present invention to provide an apparatus and method that overcomes the problems of known techniques for forming flanges to join a first panel and a second panel of a swing panel assembly.

[0008] It is a particular object of the present invention to provide tooling to consistently and repeatable stake the flange formed on a first panel for securing the second panel thereto.

[0009] Another object of the present invention is to provide such tooling with sufficient flexibility to accommodate panels of various sizes, shapes, and contours.

[0010] A further object of the present invention is to provide tooling that may be used in conjunction with a robotic arm in operation with a variety of machine cells. [0011] Yet another object of the present invention is to provide a method of staking a flange seam joining a pair of panels.

[0012] In accordance with the present invention an apparatus to join a panel assembly with a flange includes a forming stake assembly operatively associated with a programmable positioning apparatus in the form of a robotic arm, and a machine cell which includes a holder for a first panel in the form of a lower nest, and a holder for a second panel in the form of an upper gate. As presently preferred, the forming stake is disposed on a robotic end effector which includes a biasing element to ensure consistent and repeatable staking of dimples in the flange. The end effector assembly includes a cylinder head with a captured reciprocating piston. A biasing element in the form of a compression spring is operably disposed within the cylinder and atop the piston. The biasing element urges the piston to an extended position. At least one staking element is located on an extension of the piston and is oriented generally parallel to the axis of reciprocation of the piston.

[0013] In accordance with the present invention a method of joining a set of panels includes supporting a first panel in a nest such that a periphery of the first panel is supported on a material contacting portion of the nest. A second panel is positioned adjacent to a back surface of the first panel. A portion of the first panel is formed over a periphery of the second panel to provide a flange such that the second panel is located between the flange and a show surface of the first panel. The flange is staked in a direction generally normal thereto for forming a series of dimples. The dimples engage the second panel for retaining its position with respect to the first panel without deforming the show surface of the first panel. An adhesive may be disposed within the flange to further secure the panel assembly.

[0014] These and other objectives are accomplished by the provision of an apparatus and method for the forming and joining of sheet material as set forth hereinafter. Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS [0015] The present invention will be more fully understood by reference to the following detailed description of the preferred embodiments when read in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout the views, and in which:

[0016] Figure 1 is a perspective view of a machine cell incorporating an end effector having a forming stake according to the preferred embodiment of the present invention;

[0017] Figure 2 is a sectional view of a first embodiment of the end effector of the present invention viewed from the side and illustrating a forming stake in its pounce position; [0018] Figure 3 is a sectional view of the end effector shown in Figure

2 but illustrating the forming stake in its engaged position;

[0019] Figure 4 is a sectional view of a second embodiment of the end effector of the present invention viewed from the side and illustrating a forming stake in its pounce position; [0020] Figure 5 is a sectional view of the end effector shown in Figure

4 but illustrating the forming stake in its engaged position;

[0021] Figure 6 is a sectional view similar to that of Figure 2 but illustrating a third embodiment of the end effector in accordance with the present invention; and [0022] Figure 7 is a flow chart showing the method of joining a pair of panels into a panel assembly in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The drawings disclose the preferred embodiments of the present invention. While the configurations according to the illustrated embodiments are preferred, it is envisioned that alternate configurations of the present invention may be adopted without deviating from the invention as portrayed. With this understanding, the preferred embodiments are discussed hereafter.

[0024] With reference first to Figure 1 , the preferred embodiment of a machine cell 10 is illustrated in a perspective view. The machine cell 10 includes an upper gate 20 and a lower nest 30 for precisely locating sheet materials or panels A and B in a proper relative position. The machine cell 10 holds panels A and B so that a forming process may be undertaken without the panels A and B being caused to shift or otherwise move out of position. As illustrated, first panel A and second panel B have a generally square configuration. In some instances, two panels may have a varied geometry. There may also be instances where more than two panels are joined to form the panel assembly. Thus, it is to be understood that the shape and number of sheet material being formed may vary without departing from the scope of the present invention. It should also be understood that the configuration of the machine cell 10 as illustrated is preferred, but is not to be interpreted as limiting as other configurations conceivable to those skilled in the art may also be suitable. However, a presently preferred nest and gate configuration is disclosed in PCT/US04/34238, which is expressly incorporated by reference herein.

[0025] An end effector 50 is operatively associated with a robotic arm 42. The end effector 50 rigidly mounts to a robotic arm faceplate 44 that is rotatably connected to the robotic arm 42. The robotic arm 42 is itself operatively associated with a computer 46 which executes a run-time program for moving the end effector 50 through a pre-defined tool path. The end effector 50 includes a forming stake 70 having a configuration (I.e., taper, point, radius, etc.) as dictated by the particular staking operation to be performed and material to be staked. The end effector 50 may be selectably rotated to perform a desired operation with a given forming stake.

[0026] A cross-section of the end effector 50 is shown in Figures 2 and 3. With respect to these figures, the end effector 50 includes a reciprocating hub 52 having a piston end 54 mounted in a cylinder 56. The cylinder 56 is fitted rigidly to the faceplate 44 (shown in Figure 1 ) of the robotic arm 42 as is known in the art. The piston end 54 is captured within the cylinder 56 such that the hub 52 slides or reciprocates along an axis relative to the cylinder 56. Hub 52 has an extension 68 extending outwardly therefrom on the end opposite piston end 54. Forming stake 70 is secured to the extensions 68 in a direction generally parallel to the longitudinal axis of cylinder 56. [0027] A biasing element or spring 58 is interposed between the cylinder 56 and the piston end 54 to biases the hub 52 away from the cylinder 56. As an alternative to the use of the illustrated spring biasing element 58, a gas-charged cylinder may be placed in the position of the spring 58 to provide the needed biasing. In this manner, the end effector 50 provides a positional pressure forming tool whereby the position of the robot arm faceplate 44 relative to the lower nest 30 dictates the applied pressure at the interface between the flange F and the forming stake 70.

[0028] The characteristics of the biasing element are such that the pressure applied at the forming stake 70 is linearly proportional to the position of the piston end 54 relative to the cylinder 56 and the faceplate 44. Each unit of linear distance the piston end 54 moves into cylinder 56 will increase the bias of element 58 in a linear proportion. In the event that a gas-filled cylinder is used in lieu of the spring 58, a charge is built up therein and the piston end 54 moves into cylinder 56. This relationship is the basis for the positional pressure variance programming that the robotic arm plays.

[0029] The number and configuration of the extension 68 and forming stake 70 will be dictated by the particular staking operation as mentioned above. For example, the end effector may incorporate multiple forming stakes or alternately incorporate other forming tools such as a forming steel and roller as presently illustrated in Figures 4-6. For example, a forming steel 72 and a flange roller mechanism 74 may be incorporated into the end effector 50 to provide a multi-functional end effector capable of performing the complete forming and joining operations of the panel assembly. Further details concerning the flange roller mechanism 74 are set forth in PCT Application No. PCT/US04/38993 entitled "Roller Tool and Positional Pressure Method of Use for the Forming and Joining of Sheet Metal" filed on November 19, 2004 by the applicant of the present invention, the disclosure of which is hereby incorporated by reference. Likewise, further details concerning the forming steel 72 are set forth in PCT

Application No. PCT/US04/ entitled "Short Flanged Sheet Material

Forming and Joining" filed on December 2nd, 2004 by the applicant of the present invention, the disclosure of which is hereby incorporated by reference. Thus, one skilled in the art will recognize that the present invention affords the ability to perform multiple flange forming and joining operations with a single end effector.

[0030] With reference now to Figure 6, an alternate embodiment of an end effector 150 in which the placement of the hub 152 and the cylinder 156 are reversed relative to the. robotic arm face plate 144. Specifically, hub 152 extends from faceplate 144. Cylinder 156 is slidably supported on the hub 152 by a bearing sleeve 154 interposed therebetween. A spring 158 is operably coupled between the hub 152 and the cylinder 156 to bias the cylinder 156 away from the hub 152. A support flange 164 extends from the sidewall of cylinder 156. The support flange 164 is adapted to retain the forming stake 170 in a manner similar to that described with reference to Figures 2-5. Support flange 164 is also adapted to retain a forming steel 168. A roller assembly 160 may also be configured on end effector 150. The configuration of the embodiment illustrated in Figure 6 yields a more compact design than that illustrated in Figures 2-5, thereby enabling the use of end effector 150 in staking operations performed in more confined spaces. Rod 166 extends through hub 152 and slots 172, 172' formed in cylinder 156. The rod 166 cooperates with slots 172 and 172' to provide a stop or limit on the range of motions of the cylinder 156 relative to the hub 152. It is to be understood that other aspects of the alternate embodiment of end effector 150 including its utilization in the forming operation are substantially similar to that of end effector 50.

[0031] With continued reference to the figures and in particular Figure 7, the operation of joining a pair of panels in the machine cell 10 will now be generally described. A first panel A is loaded into the machine cell 10 at block 200. The first panel is then approximated onto the lower nest 30 and precision positioned by means of crowders 34 at block 202. A second panel B is loaded into the machine cell 10 at block 204. At a point in time prior to the second panel being loaded into the machine cell 10, a bead of adhesive is deposited on at least a portion of the first panel A and/or the second panel B in the area where the two panels are to be joined. The second panel B is placed on top of the first panel A and aligned with an upper gate 20 at block 206. The first and second panels A and B are then securely held in place either by known means or by a vacuum system and upper gate such as disclosed in PCT/US04/34238. With the panels so fixed, a flange forming operation is performed at block 208 to form a portion of the first panel A over the periphery of the second panel B by suitable means, preferably using a positional pressure variance unit (PPVU) 50 such as disclosed in PCT/US04/38993.

[0032] Once the flange is formed, a staking operation is performed at block 210. In the staking operation, the robotic arm 42 orients the forming stake 70 to a pounce position which is normal to and above the associated flange F of interest. In other words, the forming stake 70 is adjacent to (but not in contact with) the flange F on sheet A as seen in Figure 2. The robotic arm 42 lowers the forming stake 70 onto the flange F to form a dimple in flange F as seen in Figure 2. Lowering the robotic arm 42 so that the forming stake 70 deforms the flange also loads the biasing element 58 of the end effector 50 to remove backlash from the robotic system 40 with enough static energy to precisely locate the forming stake 70 with the desired force to form a dimple with sufficient depth to retain the location of the second panel relative to the first panel without damaging the show surface (i.e. the surface opposite the flange F) of the first panel A. A computer 46 having a tool-driving program directs the robotic arm 42 to move the forming stake 70 through a tool path along the flange F and repeats the staking operation so that a sufficient number of dimples are formed to ensure retention of the first and second panels A and B. As presently preferred a minimum of two dimples are formed to retain the panel assembly in proper alignment. Once the staking operation is complete, the robotic arm 42 manipulates the end effector 50 away from the machine cell 10. The upper gate 20 is positioned away from the panel assembly which may be immediately unloaded and moved out of the machine cell 10, without the two panels sliding out of joined alignment, and placed into a curing station at block 212, thus providing sufficient time for the adhesive to cure without idling the machine cell 10.

[0033] Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. Therefore, while this invention has been described in connection with the particular examples thereof, the true scope of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification and following claims.

Claims

CLAIMS What is claimed is:

1. An apparatus for short flange forming, the apparatus comprising: a nest adapted to hold a first panel member, said nest having a material-contacting portion; a gate adapted to position a second panel member; and an end effector operatively associated with a robotic arm, said end effector having a forming stake extending therefrom, said robotic arm positioning said end effector relative to said nest such that said forming stake cooperates with said material-contacting portion to perform a staking operation.

2. The apparatus of Claim 1 wherein said end effector comprises a positional pressure forming tool operatively associated with said robotic arm.

3. The apparatus of Claim 2 wherein the positional pressure forming tool further comprises a cylinder and a hub supported within said cylinder for relative sliding movement.

4. The apparatus of Claim 3 further including a biasing element interposed between said cylinder and said hub.

5. The apparatus of Claim 4 wherein said biasing element is a spring.

6. The apparatus of Claim 1 wherein said end effector comprises an extension extending outwardly therefrom with said forming stake is disposed on said extension.

7. The apparatus of claim 6 wherein said end effector further comprises a second extension extending outwardly from said end effector with a forming steel disposed on said second extension.

8. The apparatus of Claim 7 wherein said end effector comprises a positional pressure forming tool operatively associated with said robotic arm.

9. The apparatus of Claim 1 wherein end effector further comprises a roller rotatably supported thereon.

10. The apparatus of claim 9 wherein said end effector further comprises: a first extension extending outwardly therefrom with said forming stake disposed on said extension; and a second extension extending outwardly from said end effector with a forming steel disposed on said second extension.

11. The apparatus of Claim 10 wherein said end effector comprises a positional pressure forming tool operatively associated with said robotic arm.

12. An apparatus for joining a first sheet material to a second sheet material, the apparatus comprising: a nest for holding a first sheet material such that a flange formed on said first sheet material is supported on a material-contacting portion of said nest; a gate for locating a second sheet material on said first sheet material such that an edge of said second sheet material is located within said flange of said first sheet material; a joining mechanism operatively associated with said nest, said joining mechanism including a robotic arm and an end effector having a forming stake extending therefrom to stake said flange in a direction generally perpendicular thereto; and a computer having a tool-driving program operatively associated with said joining mechanism to position said joining mechanism at a plurality of discrete locations along said flange.

13. The apparatus of Claim 12 wherein said end effector comprises a positional pressure forming tool operatively associated with said robotic arm.

14. The apparatus of Claim 13 wherein said end effector further comprises a cylinder and a hub supported within said cylinder for relative sliding movement.

15. The apparatus of Claim 14 further including a biasing element interposed between said cylinder and said hub.

16. The apparatus of Claim 15 wherein said biasing element is a spring.

17. The apparatus of Claim 21 wherein said end effector comprises an extension extending outwardly therefrom with said forming stake disposed on said extension.

18. The apparatus of claim 17 wherein said end effector further comprises a second extension extending outwardly from said end effector with a forming steel disposed on said second extension.

19. The apparatus of Claim 18 wherein said end effector comprises a positional pressure forming tool operatively associated with said robotic arm.

20. The apparatus of Claim 12 wherein end effector further comprises a roller rotatably supported thereon.

21. The apparatus of claim 20 wherein said end effector further comprises: a first extension extending outwardly therefrom with said forming stake disposed on said extension; and a second extension extending outwardly from said end effector with a forming steel disposed on said second extension.

22. The apparatus of Claim 21 wherein said end effector comprises a positional pressure forming tool operatively associated with said robotic arm.

23. A method for joining a first panel having a first periphery with a second panel, the method comprising: holding a first panel in a nest such that a first periphery of said first panel is supported on a material-contacting portion of said nest; positioning a second panel having a second periphery adjacent a back surface of said first panel; forming a portion of said first periphery over said second periphery to provide a flange, said second panel being located between said flange and a show surface of said first panel; and staking said flange in a direction generally normal thereto to form a dimple therein, said dimple engaging said second panel to retain said second panel in position with respect to said first panel without deforming said show surface thereof.

24. The method of Claim 23 further comprising executing a end effector-driving program in a controller to manipulate said robotic arm along said flange.

25. The method of Claim 24 further comprising repeating said staking operation to form a plurality of dimples in said flange without deforming said show surface thereof.

26. The method of Claim 23 further comprising manipulating a position of said robotic arm relative to said nest to apply a predetermined pressure between said forming stake and said material-contacting portion.