US20110061406A1

US20110061406A1 - Method of cooling stretch-formed-part

Info

Publication number: US20110061406A1
Application number: US12/559,540
Authority: US
Inventors: Richard M. Kleber; Nicholas M. Bosway
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2009-09-15
Filing date: 2009-09-15
Publication date: 2011-03-17

Abstract

One exemplary embodiment of a method includes removing an automotive part from a stretch forming machine. The method also includes spraying a coolant over at least a portion of an exterior surface of the automotive part in order to cool the automotive part to a lower temperature so that the automotive part is nonmalleable and is not as susceptible to the forces of gravity as it might otherwise be.

Description

TECHNICAL FIELD

The technical field generally relates to stretch forming processes and ways to cool parts made by stretch forming processes.

BACKGROUND

Stretch forming processes, such as quick plastic forming and super plastic forming, often include heating metal sheets and stretching the metal sheets by gas pressure into desired shapes. The automotive industry uses these processes to form parts such as body panels. After heating and stretching, the shaped metal sheets are commonly placed and rest on fixtures to cool. Some shaped metal sheets, such as those eventually forming relatively large automotive hood outer panels, might sag due to gravity or otherwise distort as they are resting and cooling from a high temperature malleable state to a lower temperature less malleable state.

SUMMARY OF EXEMPLARY EMBODIMENTS OF THE INVENTION

One exemplary embodiment includes a method which may include removing an automotive part from a stretch forming machine. The method may also include spraying a coolant over at least a portion of an exterior surface of the automotive part to cool the automotive part to a lower temperature nonmalleable state.
One exemplary embodiment includes a method which may include lifting an automotive part out of a first forming tool half of a stretch forming machine. The method may also include carrying the automotive part from the stretch forming machine to a conveyer. The method may further include placing the automotive part on the conveyer. And the method may include spraying a coolant over at least a portion of an exterior surface of the automotive part as the automotive part is being carried from the stretch forming machine to the conveyer and before the automotive part is placed on the conveyer.
One exemplary embodiment includes a method which may include stretch forming an automotive part using a stretch forming machine. The method may also include removing the automotive part from the stretch forming machine. The method may further include carrying the automotive part away from the stretch forming machine. The method may include spraying a coolant over at least a portion of an exterior surface of the automotive part as the automotive part is being carried away from the stretch forming machine.
Other exemplary embodiments of the invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while disclosing exemplary embodiments 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

Exemplary embodiments of the invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is a schematic view of an exemplary embodiment of a stretch forming process with an automotive part located in a stretch forming machine.

FIG. 2 is a schematic view of the stretch forming process of FIG. 1 with the automotive part being carried away from the stretch forming machine.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description of the embodiment(s) is merely exemplary (illustrative) in nature and is in no way intended to limit the invention, its application, or uses.
The figures illustrate an exemplary embodiment of a stretch forming process such as a quick plastic forming (QPF) process or a super plastic forming (SPF) process. In the automotive industry, for example, this process may be used to form an automotive part 10 such as a relatively large body panel like a hood outer panel. In the stretch forming process, a cooling process may be used that may prevent the automotive part 10 from sagging due to gravity or otherwise distorting.
In one exemplary stretch forming process, a sheet metal substrate or blank may be placed in a stretch forming machine 12 (e.g., quick plastic forming machine or super plastic forming machine) at a workstation or forming cell, and placed between an upper or first forming tool half 14 and a lower or second forming tool half 16. In select embodiments, this sheet metal blank may include magnesium alloys, aluminum alloys, a low carbon steel, or another suitable material. An exterior surface of the sheet metal blank, or a part thereof, may be coated with a dry lubricant. An upper or first forming press 18 and a lower or second forming press 20 may be brought together under force and may clamp and seal a periphery of the sheet metal blank via the first and second forming tool halves 14, 16. The first and second forming tool halves 14, 16 may then be heated and may in turn heat the sheet metal blank to a suitable forming temperature (e.g., in the case of magnesium-containing aluminum the temperature may range between 400° C.-510° C.). A continually increasing gas pressure may then be applied to one side of the sheet metal blank (e.g., 0 p.s.i. gauge to 250-500 p.s.i. or higher) and the sheet metal blank may be forced against and may take on the shape of the forming tool half located opposite the gas pressure application. Exemplary gases may include air, nitrogen, argon, and others. In the example of FIG. 1, the sheet metal blank may take on the female or somewhat concaved-shaped second forming tool half 16. In other embodiments the stretch forming process may have more, less, and/or different steps than shown and described. For example, pre-forming processes such as heating and bending may be performed to the sheet metal blank before the sheet metal blank is placed in the stretch forming machine 12. Illustrative examples of stretch forming processes may be found in U.S. Pat. Nos. 6,253,588 and 5,974,847.
After the sheet metal blank takes the general shape of the automotive part 10, the first and second forming tool halves 14, 16 may be brought apart (i.e., opened) and the automotive part may be removed out of the stretch forming machine 12. A part removal process and system may be used to take the automotive part 10 out of the stretch forming machine 12. The part removal system may have many forms and arrangements. In the example of FIGS. 1 and 2, a robotic gantry system 22 may be used and may include one or more rails 24, multiple wheels 26, a frame 28, and multiple clamps 30. In use, the frame 28 may move horizontally between the opened first and second forming tool halves 14, 16 via the wheels 26 rolling against the rails 24. The clamps 30 may then be lowered vertically to grip a periphery of the automotive part 10. Once gripped, the clamps 30 may be raised to lift the automotive part 10 out of the second forming tool half 16, and the frame 28 may then carry the automotive part to a conveyer 32 and may place the automotive part on the conveyer. In other embodiments, the part removal process and system may have more, less, and/or different steps than shown and described. For example, the conveyer 32 need not necessarily be provided whereby the gantry system 22 would set the automotive part 10 down at another location, the transit between the stretch forming machine 12 and the conveyer need not necessarily be a straight line, and other robotic automation equipment may be used in addition to or instead of the gantry system.
Before the automotive part 10 is placed on the conveyer 32, the cooling process may be performed to the automotive part via a cooling system 34. The cooling process may help prevent sagging and other distortion caused by gravity and other effects to the automotive part 10 when the automotive part is in a high temperature and malleable state upon exiting the stretch forming machine 12. The cooling process may begin cooling the automotive part 10 as soon as possible in order to bring the part to a lower temperature nonmalleable state. In one example, the lower temperature nonmalleable state may be a rigid state where the part is not susceptible to and resists deformation due to the forces of gravity. One example lower temperature nonmalleable state is room temperature; of course, other lower temperature nonmalleable states other than room temperature may exist. The exact lower temperature nonmalleable state may depend on, among other things, the material used for the sheet metal blank and the thickness and size of the sheet metal blank.
The cooling system 34 may have many forms and arrangements. In the example of FIGS. 1 and 2, the cooling system 34 may include a first hose 36 that communicates with a coolant supply tank (not shown) and with a first manifold 38. A coolant, such as CO₂, may be stored in the coolant supply tank. The cooling system 34 may also include a first and second nozzle 40, 42 communicating with the first manifold 38. In use, coolant flows from the coolant supply tank, through the first hose 36, through the first manifold 38, and out the first and second nozzles 40, 42. The cooling system 34 may be retrofitted to the part removal system. For example, the first manifold 38 and the first and second nozzles 40, 42 may be connected to the frame 28 of the gantry system 22, and may move with the frame. The first and second nozzles 40, 42 may be located horizontally between the clamps 30 and may be directed at the exterior of the automotive part 10. The first and second nozzles 40, 42 may constitute an initial and primary set of nozzles of the cooling system 34.
The cooling system 34 may also include a second hose 44 that may communicate with the same supply tank as the first hose 36, or may communicate with another coolant supply tank. The second hose 44 may also communicate with a second manifold 46 which itself may communicate with a third and fourth nozzle 48, 50. In use, coolant flows from the coolant supply tank through the second hose 44, through the second manifold 46, and out the third and fourth nozzles 48, 50. The second manifold 46 and the third and fourth nozzles 48, 50 may be connected to a stationary support 52. The stationary support 52 may be located away from the stretch forming machine 12 as shown in FIGS. 1 and 2, or may be located near and may even extend from the stretch forming machine. The third and fourth nozzles 48, 50 may be positioned and directed to spray coolant to the exterior of the automotive part 10 as the automotive part is in transit from the stretch forming machine 12 to the conveyer 32. The third and fourth nozzles 48, 50 may constitute a final or secondary set of nozzles.
In other embodiments, the cooling system 34 may have more, less, and/or different components than shown and described. For example, more nozzles may be provided for the cooling system 34 and at different locations such as on the stretch forming machine 12, the cooling system need not have the third and fourth nozzles 48, 50 whereby only the first and second nozzles 40, 42 would be provided, and mechanical devices and ways other than nozzles may be used to spray coolant to the automotive part 10.
In the cooling process, the cooling system 34 may cool the automotive part 10 as the part is exiting the stretch forming machine 12 and before the part is placed on the conveyer 32. The first and second nozzles 40, 42 may begin spraying a first or upper exterior surface 54, or a portion thereof, of the automotive part 10 before the third and fourth nozzles 48, 50 begin spraying a second or lower exterior surface 56 of the part, or a portion thereof. In the female-shaped second forming tool half 16 of FIGS. 1 and 2, the first and second nozzles 40, 42 may begin spraying the automotive part 10 as soon as the clamps 30 grip the automotive part and while the automotive part is still seated in the second forming tool half. In some cases, depending on the exact shape of the automotive part 10, spraying the automotive part while it is still in the second forming tool half 16 may facilitate lifting and removal of the automotive part out of the second forming tool half because of the resulting slight reduction in size of the automotive part as the part cools. In a male-shaped forming tool half (not shown), the first and second nozzles 40, 42 may begin spraying the automotive part 10 after the automotive part has been lifted out of the forming tool half. Of course, in a female-shaped forming tool half, the spraying may begin after the automotive part is lifted out of the forming tool half; and likewise, in a male-shaped forming tool half, the spraying may begin once the part is gripped and while it is still seated in the forming tool half.
After the automotive part 10 is lifted out of the second forming tool half 16, the gantry system 22 may move the part toward the conveyer 32 and toward the third and fourth nozzles 48, 50. Referring to FIG. 2, once the automotive part 10 is located in the vicinity of the third and fourth nozzles 48, 50, the third and fourth nozzles may begin spraying the part. In one embodiment, the fourth nozzle 50 may begin spraying before the third nozzle 48 because the automotive part 10 may be located in the vicinity of the fourth nozzle before the third nozzle. The first and second nozzles 40, 42 may stop spraying the automotive part 10 once the automotive part is located or placed on the conveyer 32, and the third and fourth nozzles 48, 50 may stop spraying the automotive part after it is carried out of the vicinity the third and fourth nozzles.
While in transit between the stretch forming machine 12 and the conveyer 32 (or another location), the first and second nozzles 40, 42 may continuously spray coolant to the automotive part, may intermittingly spray coolant, or may spray coolant another way. Likewise, while the automotive part 10 is in transit and within the vicinity of the third and fourth nozzles 48, 50, the third and fourth nozzles may continuously spray coolant to the automotive part, may intermittingly spray coolant, or may do so another way. In one embodiment, the gantry system 22 may continuously carry the automotive part 10 from the stretch forming machine 12 to the conveyer 32 (or another location) without the cooling system 34 causing delay or a stop in the movement of the gantry system. In another embodiment, the gantry system 22 may carry the automotive part 10 in the vicinity of the third and fourth nozzles 48, 50 and may pause over the third and fourth nozzles temporarily while the third and fourth nozzles spray coolant to the automotive part. Or the gantry system 22 may carry the automotive part 10 from the stretch forming machine 12 to the conveyer 32 (or another location) more slowly than it otherwise would so that the duration of spraying coolant may be prolonged. The exact coolant spraying process (e.g., beginning of spraying, continuous or intermittent spraying, continuous or pause in transit, and speed of transit) may depend on, among other things, the thickness of the automotive part 10, the material of the automotive part, the amount of coolant flowing out of the various nozzles, and the like. Once the automotive part 10 is sufficiently cooled, (i.e., lower temperature nonmalleable state), the gantry system 22 releases and places the automotive part onto the conveyer 32 (or another location) and the automotive part is taken away for further processing.
The cooling system 34 may provide a streamlined cooling process. The cooling system 34 may be integrated in the removal and transit process so that the automotive part 10 can be brought directly to the conveyer 32 (or another location) from the stretch forming machine 12. By cooling the automotive part 10 in concert with removal and transit, the structural integrity of the automotive part 10 may be unaffected by the forces of gravity or other effects. The cooling system 34 may reduce the amount of time that the forces of gravity can act on the automotive part 10 while the automotive part is in the higher temperature malleable state. The cooling system 34 may also expedite the overall stretch forming process.
The above description of embodiments of the invention is merely exemplary in nature and, thus, variations thereof are not to be regarded as a departure from the spirit and scope of the invention.

Claims

1. A method comprising:

removing an automotive part from a stretch forming machine; and

spraying a coolant to at least a portion of an exterior surface of the automotive part to cool the automotive part to a lower temperature nonmalleable state.

2. A method as set forth in claim 1 wherein removing further comprises clamping the automotive part, lifting the automotive part out of a first forming tool half of the stretch forming machine, and carrying the automotive part away from the forming tool half.

3. A method as set forth in claim 1 wherein spraying the coolant begins as the automotive part is being removed out of the stretch forming machine and before the automotive part is completely removed out of the stretch forming machine.

4. A method as set forth in claim 1 wherein spraying the coolant comprises spraying the coolant via at least a first nozzle to a first side of the automotive part, and spraying the coolant via at least a second nozzle to a second side of the automotive part opposite the first side.

5. A method as set forth in claim 4 wherein the first nozzle is connected to a part removal system that removes the automotive part from the stretch forming machine, and the second nozzle is connected to a stationary support that is located away from the stretch forming machine, wherein spraying the coolant via the first nozzle begins at least as soon as the part removal system lifts the automotive part out of a forming tool half of the stretch forming machine, and wherein spraying the coolant via the second nozzle begins as soon as the automotive part is carried by the part removal system in the proximity of the second nozzle.

6. A method as set forth in claim 5 wherein the part removal system is a gantry system.

7. A method as set forth in claim 1 further comprising placing the automotive part onto a conveyor immediately after spraying the coolant to the automotive part.

8. A method as set forth in claim 1 wherein the coolant is CO₂.

9. A method comprising:

lifting an automotive part out of a first forming tool half of a stretch forming machine;

carrying the automotive part from the stretch forming machine to a conveyor;

placing the automotive part on the conveyer; and

spraying a coolant to at least a portion of an exterior surface of the automotive part as the automotive part is being carried from the stretch forming machine to the conveyor and before the automotive part is placed on the conveyer.

10. A method as set forth in claim 9 wherein lifting and carrying the automotive part is performed via a part removal system, and spraying the coolant is performed via at least one first nozzle connected to the part removal system.

11. A method as set forth in claim 10 wherein spraying the coolant is performed via at least one second nozzle connected to a stationary support, the at least one second nozzle spraying the coolant to the exterior surface after the automotive part is lifted out of the first forming tool half and before the automotive part is placed on the conveyer.

12. A method as set forth in claim 11 wherein the at least one first nozzle begins spraying the coolant before the at least one second nozzle begins spraying the coolant.

13. A method as set forth in claim 12 wherein the at least one second nozzle sprays the coolant to the exterior surface as the automotive part is in transit between the stretch forming machine and the conveyer, the automotive part substantially continuously moving between the stretch forming machine and the conveyor.

14. A method comprising:

stretch forming an automotive part via a stretch forming machine;

removing the automotive part from the stretch forming machine;

carrying the automotive part away from the stretch forming machine; and

spraying a coolant to at least a portion of an exterior surface of the automotive part as the automotive part is being carried away from the stretch forming machine.

15. A method as set forth in claim 14 wherein stretch forming comprises quick plastic forming via a quick plastic forming machine.

16. A method as set forth in claim 14 wherein spraying the coolant is performed via at least one first nozzle connected to a part removal system and via at least one second nozzle connected to a stationary support.

17. A method as set forth in claim 16 wherein the at least one first nozzle begins spraying the coolant before the at least one second nozzle begins spraying the coolant.