US20220040747A1

US20220040747A1 - Flat top metal gainer

Info

Publication number: US20220040747A1
Application number: US16/986,449
Authority: US
Inventors: Dajun Zhou; Chunlei Wang; Robert D Miller
Original assignee: Individual
Current assignee: FCA US LLC
Priority date: 2020-08-06
Filing date: 2020-08-06
Publication date: 2022-02-10

Abstract

A method of forming a metal part that includes placing a metal blank in a stamping apparatus having a first die including a plurality of metal gainers and a second die including a plurality of recesses that correspond to the plurality of metal gainers, and compressing the metal blank such that the metal gainers and the corresponding recesses provide the metal blank with regions of localized stretching. Each of the metal gainers and recesses includes a flat surface such that during the compressing of the metal blank to provide the metal blank with the regions of localized stretching, a strain exerted on the metal blank by the metal gainers and recesses is less than a strain exerted on the metal blank by metal gainers and recesses that do not include the flat surface.

Description

FIELD

The present disclosure relates to a stamping method and system that uses a metal gainer having a flat top for providing additional material before a flanging operation is conducted.

BACKGROUND

Many manufacturing processes are available to form sheet metal blanks into parts in a wide variety of industries. For example, drawing and deep drawing of sheet metal blanks is a process in which the metal blank is drawn between an upper die and a lower die to take a shape that initially resembles the shape of the finished part. Additional manufacturing process might also take place after the drawings. For example, flanging can bend an end region of the metal blank to form a flange. When these flanges are formed, however, there may be residual stress in regions of the flange that can distort the final shape of the part due to the stretching and bending of the metal to form the flange.
In addition, when the metal blank is formed from an advanced high strength metal such as an ultra-high strength steel or a 7000 series aluminum alloy, the metal blank may have poor ductility and/or formability. The reduced formability of these newer materials may result in cracks, necking, or other imperfections during the flanging process. Any of these imperfections may compromise the integrity of the finished part, and are simply not acceptable in commercial products, including automotive applications.

SUMMARY

The present disclosure provides a method of forming a metal part that includes placing a metal blank in a stamping apparatus having a first die including a plurality of metal gainers and a second die including a plurality of recesses that correspond to the plurality of metal gainers, and stretching the metal blank such that the metal gainers and the corresponding recesses provide the metal blank with regions of localized stretching; and subjecting the metal blank including the regions of localized stretching to a stretch-flanging process; wherein each of the metal gainers and recesses includes a flat surface surrounded by a side surface such that during the stretching of the metal blank to provide the metal blank with the regions of localized stretching, a combined strain exerted on the metal blank by the metal gainers and recesses that include the flat surface in combination with the stretch-flanging process is less than a combined strain exerted on the metal blank by traditional metal gainers and recesses that do not include the flat surface in combination with the stretch-flanging process.
The present disclosure also provides a method of forming a metal part that includes placing a metal blank in a stamping apparatus having a first die including a plurality of metal gainers and a second die including a plurality of recesses that correspond to the plurality of metal gainers, and stretching the metal blank such that the metal gainers and the corresponding recesses provide the metal blank with regions of localized stretching; and subjecting the metal blank including the regions of localized stretching to a stretch-flanging process; wherein each of the metal gainers and recesses includes a flat surface surrounded by a side surface such that during the stretching of the metal blank to provide the metal blank with the regions of localized stretching, a curve that graphically represents the strains exerted on the metal blank at the regions of localized stretching exhibits a pair of peaks at different locations rather than a single peak when the metal blank is stretched between metal gainers and recesses that do not have the flat surface.
Lastly, the present disclosure provides a stamping press that includes a first die including a plurality of protrusions; and a second die including a plurality of recesses that correspond to the plurality of protrusions, wherein the plurality of protrusions in combination with the plurality of protrusions are configured to provide a metal blank with regions of localized stretching when the metal blank is stretched between the plurality of protrusions and the plurality of recesses, and wherein each of the protrusions and each of the recesses includes a flat surface surrounded by a side surface such that during the stretching of the metal blank to provide the metal blank with the regions of localized stretching, a curve that graphically represents the strains exerted on the metal blank at the regions of localized stretching exhibits a pair of peaks at different locations rather than a single peak when the metal blank is compressed between metal gainers and recesses that do not have the flat surface.
Further areas of applicability of the teachings of the present disclosure will become apparent from the detailed description, claims and the drawings provided hereinafter, wherein like reference numerals refer to like features throughout the several views of the drawings. It should be understood that the detailed description, including disclosed embodiments and drawings referenced therein, are merely exemplary in nature intended for purposes of illustration only and are not intended to limit the scope of the present disclosure, its application or uses. Thus, variations that do not depart from the gist of the present disclosure are intended to be within the scope of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a body panel or fender manufactured using the teachings of the present disclosure;

FIG. 2 is a cross-sectional view of the body panel or fender illustrated in FIG. 1 along line 2-2 of FIG. 1;

FIG. 3 is a perspective view of a metal blank used to form the body panel or fender illustrated in FIG. 1;

FIG. 4 is a perspective view of the metal blank illustrated in FIG. 3 after being subjected to a metal-gaining (bubble) process to form regions of localized stretching in the metal blank;

FIG. 5 is a perspective view of the metal blank illustrated in FIG. 4, after undergoing a material removal process (trimming);

FIG. 6 is a perspective view of the metal blank illustrated in FIG. 5, after undergoing a flanging process;

FIG. 7 is a cross-sectional view of a stamping press including metal gainers according to a principle of the present disclosure;

FIGS. 8a to 8c are graphic representations of the strain distribution exerted on the metal blank during the metal-gaining process (FIG. 8a ) using a metal gainer that does not include a flat surface, the strain exerted on the metal blank during a stretch-flanging process (FIG. 8b ), and the combined (overlapped) total strain exerted on the metal blank during the metal-gaining process and the stretch-flanging process (FIG. 8c );

FIGS. 9a to 9c are graphic representations of the strain exerted on the metal blank during the metal-gaining process (FIG. 9a ) using a metal gainer that includes a flat surface, the strain exerted on the metal blank during the stretch-flanging process (FIG. 9b ), and the combined (overlapped) total strain exerted on the metal blank during the metal-gaining process and the stretch-flanging process (FIG. 9c ); and

FIGS. 10a to 10e are perspective views of example metal gainers having engineered shapes that result in optimized strain distributions when forming regions of localized stretching in a metal blank according to a principle of the present disclosure.

DETAILED DESCRIPTION

A stamped metal part may become dimensionally unstable or undesirable for later use in a vehicle assembly due to stresses that can be a byproduct of the metal stamping process. Depending on the function of the metal part and its location in the vehicle, the dimensional defect can cause vehicle build issues and can be visibly undesirable to the driver or customer. This undesirability may occur in a flange of a stamped part. Stretch-flanging is an operation in which a part of the metal part, such as an edge of the metal part, is bent with respect to the body. Some example regions of the vehicle body with a flanged edge include a fender door line, a roof line, a fender wheel opening, a cowling, and a liftgate outer roof line.
FIG. 1 illustrates an example body panel or fender 10 that is formed from a metal blank. In the illustrated example, fender 10 includes a main body 12 that includes a wheel opening 14. At wheel opening 14, as best shown in FIG. 2, an edge 16 of wheel opening 14 is bent using the aforementioned stretch-flanging operation to form a flange 18. Although flange 18 is illustrated as being oriented at about ninety degrees relative to main body 12, it should be understood that flange 18 can be oriented at other angles greater or lesser than ninety degrees without departing from the scope of the present disclosure. Regardless, during formation of flange 18, the material of fender 10 can be formed during the flanging process. When fender 10 is formed of an advanced high strength metal such as an ultra-high strength steel or a 7000 series aluminum alloy, which generally have poor ductility and/or formability, the flange 18 may crack during the stretch-flanging process due to the stretching of the metal material. The cracking or splitting of flange 18 is typically a result of the material of the metal blank not being able to stretch enough during the stretch-flanging process (poor edge formability).
In order to suppress cracking or splitting of the metal blank during formation of flange 18, a metal blank 20 is subjected to a stamping process where the metal material of the metal blank 20 is stretched before conducting the flanging process. FIG. 3 illustrates metal blank 20 before it has been subjected to trimming to form wheel opening 14. In this regard, the broken line 22 represents the location where wheel opening 14 will be cut during a trimming process of metal blank 20. It should be understood that metal blank 20 may have already been subjected to a drawing or deep drawing process to impart a designed contour to metal blank 20 that will correspond to that of fender 10.
Now referring to FIG. 4, it can be seen that prior to trimming of metal blank 20 to form wheel opening 14, metal blank 20 has been subjected to a stretching process. Specifically, metal blank 20 has been stamped to impart regions or bubbles 24 of localized stretching (areas of increased material) of metal blank 20 at locations along line 22 in order to reserve some additional material for a later-conducted stretch-flanging process, or to make the to-be-stretched edge line longer after trimming. Bubbles 24 are formed along line 22 because after trimming metal blank 20 to form wheel opening 14, edge 16 of wheel opening 14 will be bent to form flange 18 during the stretch-flanging process. Due to the localized stretching of metal blank 20 at bubbles 24, the material of metal blank 20 is less prone during stretch-flanging to stretch to an extent that causes the material of metal blank 20 to crack or split.
Now referring to FIG. 5, after metal blank 20 has been imparted with bubbles 24, metal blank 20 has been subjected to a trimming process where metal blank 20 is trimmed by stamping or subjected to laser cutting to remove portions of metal blank 20 to form wheel opening 14. As can be seen in FIG. 5, portions 26 of bubbles 24 remain along edge 16 of wheel opening 14. Thereafter, as shown in FIG. 6, metal blank 20 is subjected to stretch-flanging to form flange 18 along edge 16 of wheel opening 14. As can be seen in FIG. 6, the stretch-flanging process also flattens bubbles 24 such that fender 10 is formed.
The regions or bubbles 24 of localized stretching of metal blank 20 are provided by placing metal blank 20 in a stamping apparatus or stamping press die 28. An example stamping press die 28 is illustrated in FIG. 7. Stamping press die 28 includes an upper die 30 and a lower die 32. Lower die 32 includes a plurality of protrusions or metal gainers 34 formed therein. Upper 30 includes a plurality of recesses 36 that are shaped for receipt of metal gainers 34 therein. After blank 20 is placed between upper and lower dies 30, 32, blank 20 is pressed to form bubbles 24. Blank 20 is then free to be removed from stamping press 28 by an operator or robot and placed in an apparatus (not shown) configured to form wheel opening 14. Alternatively, formation of wheel opening 14 may occur at the same time as formation of bubbles 24. After formation of wheel opening 14 by trimming, the blank 20 can be placed in another apparatus (not shown) by an operator or robot to form flange 18 to complete formation of fender 10.
As noted above, due to the localized stretching of metal blank 20 at bubbles 24 that are formed by metal gainers 34, the material of metal blank 20 is less prone during stretch-flanging to stretch to an extent that causes the material of metal blank 20 to crack or split. As shown in FIG. 7, metal gainers 34 include a first flat surface 38 and recesses 36 include a corresponding second flat surface 40. The first and second flat surfaces 38 and 40 are important when stretching the material of metal blank 20 before conducting the stretch-flanging process of forming flange 18, especially when the material of metal blank 20 is an advanced high strength metal such as an ultra-high strength steel or an aluminum alloy.
More specifically, FIG. 8a graphically illustrates the strain that is exerted on metal blank during formation of the regions or bubbles 24 of localized stretching using a metal gainer 34 and recess 36 that do not have first flat surface 38 and second flat surface 40, respectively. FIG. 8b graphically illustrates the strain that is exerted on metal blank 20 during formation of the flange 18 itself. FIG. 8c graphically illustrates the combined (total) strain distribution from forming bubbles 24 using metal gainers 34 and recesses 36 that do not have first flat surface 38 and second flat surface 40, respectively, and the strain exerted on metal blank 20 during the formation of flange 18.
As can be seen in FIG. 8c , because the peaks (strains) of each process overlap, the combined final or total strain (amplitude) exerted on metal blank 20 is much greater in comparison to the strains exerted on metal blank 20 by either the metal gainer stretching process (FIG. 8a ) or flanging process (FIG. 8b ) alone. The combined strain exerted on metal blank 20, especially when metal blank 20 is formed of an advanced high strength metal, therefore, may be too great for metal blank 20 (i.e., beyond the edge stretch limit of the material), which may result in the material cracking or splitting during the stretch-flanging process.
FIG. 9a illustrates the strain that is exerted on metal blank 20 during formation of the regions or bubbles 24 of localized stretching using a metal gainer 34 and recess 36 having the first flat surface 38 and second flat surface 40, respectively, according to the present disclosure. As can be seen in FIG. 9a , when the metal gainers 34 and recesses include the first flat surface 38 and second flat surface 40, respectively, the strain exerted on metal blank 20 exhibits a curve having a pair of peaks separated by a valley. The pair of peaks result from the strain being exerted on metal blank 20 by side surfaces 42 of metal gainers 34 being greater than the strain exerted on metal blank 20 by first flat surface 38 and second flat surface 40, which are represented by the valley. FIG. 9b graphically illustrates the strain that is exerted on metal blank 20 during formation of flange 18 itself. FIG. 9b is the same as FIG. 8b because the strains exerted on metal blank 20 are the same during the stretch-flanging process. FIG. 9c graphically illustrates the combined final or total strain from forming bubbles 24 using metal gainers 34 and recesses 36 that have first flat surface 38 and second flat surface 40, respectively, and the strain exerted on metal blank 20 during the formation of flange 18.
As can be seen in FIG. 9c , because the peaks (strains) of each process (bubble making and flanging) do not overlap, the combined final or total strain (amplitude) exerted on metal blank 20 is much less in comparison to the combined strain illustrated in FIG. 8c , and is safely less than the edge stretch limit of the material. The combined strain exerted on metal blank 20, especially when metal blank 20 is formed of an advanced high strength metal, therefore, can be reduced when using metal gainers 34 and recesses 36 having first flat surface 38 and second flat surface 40, respectively, which prevents or at least substantially minimizes the risk of material cracking or tearing during the flanging process. In other words, the use of flat surfaces 38 and 40 allows for engineering the strain peak locations to avoid overlap with the strain peak that results during the stretch-flanging process such that the combined final or total strain exerted on metal blank 20 during the metal gaining and stretch-flanging processes is much less in comparison to instances when traditional metal gainers 34 and recesses 36 do not include flat surfaces 38 and 40, respectively.
Metal gainers 34 do not necessarily need to be oval-shaped, as shown in FIGS. 4 and 10 a. In contrast, metal gainers 34 can have any shape desired by one skilled in the art provided that metal gainers 34 includes a first flat surface 38, and the correspondingly shaped recesses 36 have a second flat surface 40. The shape of metal gainers 34 and recesses 36 can be engineered using a numerical forming simulation tool. For example, as shown in FIGS. 10b to 10 d, metal gainers 34 and recesses 36 may be triangular-shaped (FIG. 10b ), diamond- or square-shaped (FIG. 10c ), or round (FIG. 10d ) without departing from the scope of the present disclosure. Moreover, it should be understood that metal gainers 34 do not need to be oriented as shown in FIG. 4. In contrast, metal gainers 34 may be slightly rotated to the left or right, especially when metal gainers 34 are formed to have the shapes illustrated in FIG. 4, FIG. 10a , and FIG. 10 b.
Regardless of the shape of metal gainer 34, the important aspect of the present disclosure is to provide metal gainer 34 and recesses 36 with first flat surface 38 and second flat surface 40. First and second flat surfaces 38 and 40 may have a similar shape as that of metal gainer 34 and recess 36 as shown in FIGS. 10a to 10d , or a flat surface having a shape that is different from that of metal gainer 34 and recess 36. For example, if metal gainer 34 and recess 36 are oval-shaped, first and second flat surfaces 38 and 40 may be round, square (FIG. 10e ), or triangular if desired.
The surface area of first and second flat surfaces 38 and 40 may also be variable. For example, the surface area of flat surfaces 38 and 40 of metal gainers 34 and recesses 36 can range between 40% to 90% of the surface area of metal gainers 34 and recesses 36, more preferably between 50% to 75% of the surface area, and most preferably 60% to 70% of the surface area.
Lastly, first and second flat surfaces 38 and 40 are not necessarily planar surfaces. In contrast, as noted above, the important aspect to keep in mind is that first and second flat surfaces 38 and 40 can be designed or engineered such that metal gainers 34 and recesses 36 allow for management of the locations of the strain peaks that indicate the locations of the strains exerted on metal blank 20 in the manner shown in FIG. 9a where a pair of peaks of strain are exhibited rather than the curve illustrated in FIG. 8a . Thus, the first and second “flat surfaces” 38 and 40 may be slightly curved or slightly hemispherical so long as the management of the location of the strain peaks is similar to that shown in FIG. 9 a.

Claims

1. A method of forming a metal part, comprising:

placing a metal blank in a stamping apparatus having a first die including a plurality of metal gainers and a second die including a plurality of recesses that correspond to the plurality of metal gainers, and forming the metal blank such that the metal gainers and the corresponding recesses provide the metal blank with regions of localized stretching, the regions of localized stretching being located along a trim line of the metal blank that corresponds to a region of the metal blank that will be trimmed from the metal blank;

after providing the metal blank with the regions of localized stretching, trimming the metal blank along the trim line such that portions of regions of localized stretching remain along the trim line; and

after trimming the metal blank along the trim line, subjecting the metal blank including the regions of localized stretching to a stretch-flanging process that forms a flange at the trim line;

wherein each of the metal gainers and recesses includes a flat surface surrounded by a side surface such that during the forming of the metal blank to provide the metal blank with the regions of localized stretching, a combined strain exerted on the metal blank by the metal gainers and recesses that include the flat surface in combination with the stretch-flanging process is less than a stretch limit of a material of the metal blank.

2. The method according to claim 1, wherein a surface area of the flat surfaces of the metal gainers and the recesses ranges between 40% to 90% of a total surface area of the metal gainers and the recesses.

3. The method according to claim 1, wherein the metal gainers and recesses are at least one of oval-shaped, triangular-shaped, diamond- or square-shaped, or round.

4. The method according to claim 3, wherein a shape of the flat surface of each of the metal gainers and recesses is the same as an overall shape of the metal gainer and recess.

5. The method according to claim 3, wherein a shape of the flat surface of each of the metal gainers and recesses is different from an overall shape of the metal gainer and recess.

6. The method according to claim 1, wherein the metal blank is formed of an advanced high strength metal.

7. A method of forming a metal part, comprising:

wherein each of the metal gainers and recesses includes a flat surface surrounded by a side surface such that during the forming of the metal blank to provide the metal blank with the regions of localized stretching.

8.-9. (canceled)

10. The method according to claim 7, wherein a surface area of the flat surfaces of the metal gainers and the recesses ranges between 40% to 90% of a total surface area of the metal gainers and the recesses.

11. The method according to claim 7, wherein the metal gainers and recesses are at least one of oval-shaped, triangular-shaped, diamond- or square-shaped, or round.

12. The method according to claim 11, wherein a shape of the flat surface of each of the metal gainers and recesses is the same as an overall shape of the metal gainer and recess.

13. The method according to claim 11, wherein a shape of the flat surface of each of the metal gainers and recesses is different from an overall shape of the metal gainer and recess.

14. The method according to claim 7, wherein the metal blank is formed of an advanced high strength metal.

15. A stamping press comprising:

a first die including a plurality of protrusions; and

a second die including a plurality of recesses that correspond to the plurality of protrusions,

wherein the plurality of protrusions in combination with the plurality of protrusions are configured to provide a metal blank with regions of localized stretching when the metal blank is formed between the plurality of protrusions and the plurality of recesses, and

wherein each of the protrusions and each of the recesses includes a flat surface surrounded by a side surface such that during the forming of the metal blank to provide the metal blank with the regions of localized stretching; and

wherein a shape of the flat surface of each of the protrusions and recesses is the same as an overall shape of the protrusions and recesses.

16. The stamping press according to claim 15, wherein a surface area of the flat surfaces of the protrusions and the recesses ranges between 40% to 90% of a total surface area of the protrusions and the recesses.

17. The stamping press according to claim 15, wherein the protrusions and recesses are at least one of oval-shaped, triangular-shaped, diamond-or square-shaped, or round.

18.-19. (canceled)