CA2221076A1 - Advanced forming techniques for superplastic forming - Google Patents
Advanced forming techniques for superplastic forming Download PDFInfo
- Publication number
- CA2221076A1 CA2221076A1 CA002221076A CA2221076A CA2221076A1 CA 2221076 A1 CA2221076 A1 CA 2221076A1 CA 002221076 A CA002221076 A CA 002221076A CA 2221076 A CA2221076 A CA 2221076A CA 2221076 A1 CA2221076 A1 CA 2221076A1
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- Canada
- Prior art keywords
- blank
- cutout
- die
- forming
- pressurized gas
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D26/00—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
- B21D26/02—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure
- B21D26/053—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure characterised by the material of the blanks
- B21D26/055—Blanks having super-plastic properties
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- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Shaping Metal By Deep-Drawing, Or The Like (AREA)
Abstract
This invention defines an improved method for superplastic forming (SPF) of metallic parts in which a cutout is formed in the blank from which the parts will be formed, and a secondary sheet is located between the blank and the pressurized gas. The cutout area of the blank becomes stretched so that there is minimal thinning in the air near the peripheryof the cutout(s) in the blank, the secondary sheet is required to carry the gas pressure and to form the parts.
Description
. CA 02221076 1997-11-14 Back~round of the In~ention 1. Field of ~e Invention The present invention relates to techniques for superplastic forming of parts, and more particularly, for control of thinout in such parts.
2. Background of the Invention Superplastic forming hereinafter (SPF) is a metal forming process used throughout the aerospace industry for manufacturing detailed parts and built-up structures. The design flexibility that is offered by SPF has resulted in substantial cost savings in the fabrication of detail parts and assemblies. Further savings have been apparent in the reduc~ion of weight in aircraft. The prior art SPF process for manufacturing parts consists of several steps. ~hese steps are illustrated in FIGIJRES lA to lD and can be ~ 7.e~ as follows: heating a die to an al~plopliate temperature for a particular metal alloy; placing a metal sheet, also referred to as a blank, in the die; closing a lid to the die; applying restrair~ing forces to hold the die and lid together, applying a forming gas pressure to the blank in order to push the blank into the die cavity; completing the time required in the forming cycle; and removing the fini~hed part from the die.
FIGURE 2 shows a sçhem~tic plan view of the die with the lid removed for illustration purposes. The blank or sheet 10 is supported in the regions 12 surrounding the sealed area 14 by the lower die 16, as shown in FIGURE lA. The double lines 18 outline the seal area, within which a part will be formed. The reason that the material does not thinout uniformly is that once the lid is closed on the SPF die, the periphery of the m~t~ri~l is restrained such that the m~t~ l is not allowed to "draw-in" the material outside of the seal area.
FIGURE 3 shows a schematic cross section view of a part formed by SPF. The dotted lines show where the part will be cut or trimmed. The run-out is in the die region outside of the net part area. A correctly designed die will optirnize the run-out configuration so that thinout is rni.nimized in the part area and maxirnized in the run-out material.
FIGURE 4 is a side elevation cross-section illustrating the thinout problem. For example, the part thicknesses at 20 and 22 are very tllin, and could potentially be below the thicknesses specified by the Engineering drawing.
Summary of the Invention The present invention defines a method of increasing part thickness in specific areas of SPF details by preferentially cutting out one or more areas of the starting material '~blank".
The cut-out area of the blank becomes stretched so that minimal thinning results in the area near the periphery of the cutout. The process utilizes a second sheet of material to push the cutout blank, with cutout(s), onto the die.
Brief Description of the Drawin~s The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
FIGURES lA to lD are a side elevation cross-section drawing of a prior art SPF in four consecutive modes of operation.
FIGURE 2 is a plan view of a die with lid removed.
FIGURF 3 shows a schematic cross section of a part formed by SPF.
FIGURE 4 is a schematic side elevation cross sectional view of a die and part manufactured by SPF.
, CA 02221076 1997-11-14 FIGURES SA to 5 ~show a cross section of a die and part in six consecutive stages of the SPF process of this invention.
FIGURES 6A and 6B show how the secondary sheet of this invention can entrap the blank after forming.
FIGURE 7 is a schematic showing the axial and biaxial stresses around the cutout of this invention.
~IGURE 8 compares thickness data at various locations on SPF parts made using prior art techniques and using the techniques of this ~nvention.
Figure 9A shows an orthogonal projection of one-half of a SPF part.
Figure 9B shows a method for manipulatingdie surfaces to arrive at the size of a cutout of this invention.
FIGURE 9C illustrates a plan view of the blank after manipulating and projecting the die surfaces of Figure 9B.
Description of the Preferred Embodiment One of the greatest chaUenges associated with Superplastic Forming is predicting m~t~,ri~l thinout and then achieving that thinout duling part f~hric~tion. The m~teri~l thinout challenge is inherent to the SPF process and stems from varying m~te,ri~l thickness across the part area after SPF. Engineering drawings typically call out a minimllm allowed m~t~ l thickness across the entire part or in specific regions of the part.
The reason that material does not thinout uniformly is that once the lid is closed on the SPF die, the periphery of the material is restrained such that the material is not allowed to "draw-in" from the edges. As a result, the m~t~ri~l that will become the part area must be stretched from the material inside of the seal area.
During forming, the stretching of the material within the seal area progresses until the m~t~ l eventually contacts the die sur~ace. Upon contact, the mz~t~ l sticks to the die sur~ace. The remaining m~teri~l that has not yet contacted the die continues to stretch until it too contacts the die surface and sticks. Once the material is completely formed, the thinnest regions are generally those that are the last to form. These regions equate to the deepest areas of the die and radii, in particular spherical radii (corners).
Since material thinout is dependent on the die geometry, the die design is ~ritical in achieving the proper material thinout. Of specific importance is the die "run-out", which - is the die region outside the net part area. A correctly designed die will optimize the "run-out" configuration so that thinout is minimi7~d in the part area and maximized in the "run-out" material.
Once the part area and "run-out" of the die have been machined and the first SPF part is formed, there are only a few options for recouTse if the part is too thin according to engineering drawing requirements. The two most common options are: (1) Start with a thicker gauge of blank m~t~,ri~l, (2) Preform the blank prior to forming it into the final part configuration.
The former option is the easier of the two options to irnplement and provides relatively quick results for thickness analysis. However, it is not a ~ua~ ee for achieving the correct minimnm thickness since adding thickness to the starting blank does not equate to a sufficient thickness increase in the thinnest areas of the part. Furthermore, an increase in the starting m~t~,ri7l1 gauge adversely effects the part weight.
. CA 02221076 1997-11-14 The latter option, designing a prefor n for the blank, carries a fair amount of risk.
Designing a successful preform geometry potentially requires several iterations, an expensive and tinne consuming process. As with increasing the material gauge, preforming will not guarantee a successful part.
With this invention a third option becomes available for selectively increasing the material thickness in specific regions of the part. This option too, does not guarantee that the minimum material thinout will be attained. However, through a combination of increasing the starting gauge and utilizing this third option, the odds of attaining a successful part are significantly increased.
Depending on the part configuration, it is possible to minimi7e the material thinout by placing a strategically located cutout(s) in the starting blank. The typical applicable part configuration is one that has an area of the net trim that is in~f~rn~l to the part itself (i.e. a pocket or "bowl"). A simplified example would be a pan-shaped part that has the bottom of the pan cut away, resulting in a ring-shaped part.
Cutting out a hole(s) in the material allows for the hole(s) to enlarge as the m~t~ ri~l is stretched onto the tool surface. This enlarging takes the place of stretching and thinning the material if the holes were not present. The basic concept is that the hole enables more axial stretching of the material and minimi7e~ the biaxial stretching (ref.Figure ~. The end result is minimi7ed material thinout in the axially stretched material. The thinout in areas of the hole that are stretched biaxially is also minimized (relative to not using the cutout(s), but to a lesser extent than the axially stretched regions (ref. Figure 6 and Data Table I).
Since the SPF process uses gas pressure to form the m~t~n~l, it is imperative that the sheet being formed does not have any holes through it. This requirement is in direct opposition to the process of this invention. Subsequently, a second sheet of material that does not contain any cutout locations, is required to form the blank (material with the cutout(s). This second sheet is placed between the blank and the die lid and becomes the membrane which can be pressurized and formed onto the tool geometry. While forming, this secondary sheet also forms the blank with the cutout(s). Once the blank is fully formed (die surface is in intimate contact with the entire blank), the blank and secondary sheet are separated and the secondary sheet is discarded There are three critical factors-that must be dealt with to successfully utilize the disclosed process. Those factors are: (1) l_ocation of cutout(s) on the blank, (2) Shape and Size of the cutout(s) on the blank, and (3) Indexing the blank to the tool.
Cutout Location: The location of the cutout(s) is op~ ized when the periphery of the cutout(s) is located as close as possible to the net trim of the part after forming. Locating the cutout(s) as such will maximize the m~t~ thickness at the trim line.
Shape and Size of the Cutout(s): The cutout(s) shape and size are critical in that an un~ler~i7ed cutout will result in unnecessary thinout. Conversely, an oversized cutout will result in undercutting the trim line of the part. While both sizing and locating the cutout(s), caution must be taken so that the formed blank does not become entrapped by the secondary sheet during the separation of the two sheets (ref. Figure 6B).
. CA 02221076 1997-11-14 There are several methods for deter~rlining the proper location and size of the cutout(s) on the blanks. Besides trial and error, a highly accurate "best guess" can be made utilizing a model of the die surface. Among the most easily manipulated mode is a Computer Aided Drafting (CAD) model. Once generated, the tool surfaces can be projected or rotated to one plane so that the trim line of the part can be seen on that plane - the equivalent of a forming blank (ref. Figure 9). ~his planar trim line de~lnes a preliminary location, si~, and shape of the cutout(s). The ~mal size and shape of the cutout can then be obtained by applying a reduction factor anad corner radii to the preliminary size and shape.
Indexing the Blanlc to the Tool: Once the size, shape, and location of the cutout(s) have been detennined, it is paramount that the blank be located to the die accurately. Without accurate, repeatable alignment, it is not possible to produce a consistent part. One method of locating the blank to the die is through the use of "pins~' or "posts" that extend from the die sealing surface. Holes can then be cut into the blank and secondary sheet tocorrespond to the pins in the die.
Description of Figures:
Figure 5: Illustrates the process steps for the Disclosed Invention Prior to Figure 5A, the region(s) of the blank that are to be cutout must be removed. The location, size and geometry of the cutout(s) is of critical importance for the successful forming of the part. In addition, it is also critical that the blank be indexed to the die surface so that the cutout area(s) form into the desired areas of the die.
Figure 5A: This figure illustrates the die, die lid, material blank and the secondary sheet. Once the die is heated to the forming temperature for the particular material . . CA 02221076 1997-11-14 alloy, the blank and secondaIy sheet are placed on the surface of the die. The location of the secondary sheet is between the die lid and the blank.
Figure 5B: The blank and secondary sheet are "sandwiched" between the die and lid by means of a force applied to the lid.
Figure 5C: As gas pressure is introduced to the top side of the secondary sheet,the secondary sheet and blank are formed into the die cavity.
Figure SD: Forming continues as the gas pressure is increased.
Figure 51~: Upon completion of the forrning cycle, the blank is in full contact with the die surfaces.
Figure 5F: The gas pressure is vented and the lid is removed. The blank and secondaly sheet are separated and removed from the die.
Figure 6A: This figure illustrates the result of correctly calculating and locating the cutout(s) on the blank. In this instance, the secondary sheet does not entrap the blank when the two are separated.
Figure 6B: This figure illustrates the potential problem of material entrapment caused by incorrectly calculating the size and location of the cutout(s) on the blank. In this instance after forming, the edge of the cutout(s) became located on a near-vertical surface, creating entrapment of the blank by the secondary sheet.
This entrapment does not allow for separation of the blank and secondary sheet without cutting the two apart~
. CA 02221076 1997-11-14 Figure 7: This figure illustrates the types of stretching of the cutout periphery that take place during forming of the blank. Any straight line regions of the cutout periphery will undergo stretching in one direction ~axial). (~urved segments of the cutout will stretch in two directions (biaxial). In general, the axial stretching that takes place will result in less thinout' than in the regions that are biaxially stretched.
Figure 8: This figure illustrates data obtained from fabricated test parts. All parts started with the same material thickness and were measured in the same locations.
From the data it is possible to see that by cutting hole(s) in the blank, it is possible to achieve a 69% increase in as-formed material thickness, in comparison to parts formed without the invention process.
Figure 9: This ~lgure illustrates how the basic geometry and location of the cutout(s) can be obtained. This key information be obtained through several methods. However, the easiest method is through the manipulation of Computer Aided Drafting (CAD) data of the die geometry. Use of such data is illustrated in this ~lgure.
Figure 9A: This figure illustrates half of a symmetrical part. The dashed lines indicate surfaces of the die.
Figure 9B. This figure shows the axis about which the surfaces are rotated. Oncethe surfaces are rotated to the starting plane, a preliminary outline of the cutout can be determined. The edge of the surface rotated is determined by the net trim of the part.
FIGURE 2 shows a sçhem~tic plan view of the die with the lid removed for illustration purposes. The blank or sheet 10 is supported in the regions 12 surrounding the sealed area 14 by the lower die 16, as shown in FIGURE lA. The double lines 18 outline the seal area, within which a part will be formed. The reason that the material does not thinout uniformly is that once the lid is closed on the SPF die, the periphery of the m~t~ri~l is restrained such that the m~t~ l is not allowed to "draw-in" the material outside of the seal area.
FIGURE 3 shows a schematic cross section view of a part formed by SPF. The dotted lines show where the part will be cut or trimmed. The run-out is in the die region outside of the net part area. A correctly designed die will optirnize the run-out configuration so that thinout is rni.nimized in the part area and maxirnized in the run-out material.
FIGURE 4 is a side elevation cross-section illustrating the thinout problem. For example, the part thicknesses at 20 and 22 are very tllin, and could potentially be below the thicknesses specified by the Engineering drawing.
Summary of the Invention The present invention defines a method of increasing part thickness in specific areas of SPF details by preferentially cutting out one or more areas of the starting material '~blank".
The cut-out area of the blank becomes stretched so that minimal thinning results in the area near the periphery of the cutout. The process utilizes a second sheet of material to push the cutout blank, with cutout(s), onto the die.
Brief Description of the Drawin~s The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
FIGURES lA to lD are a side elevation cross-section drawing of a prior art SPF in four consecutive modes of operation.
FIGURE 2 is a plan view of a die with lid removed.
FIGURF 3 shows a schematic cross section of a part formed by SPF.
FIGURE 4 is a schematic side elevation cross sectional view of a die and part manufactured by SPF.
, CA 02221076 1997-11-14 FIGURES SA to 5 ~show a cross section of a die and part in six consecutive stages of the SPF process of this invention.
FIGURES 6A and 6B show how the secondary sheet of this invention can entrap the blank after forming.
FIGURE 7 is a schematic showing the axial and biaxial stresses around the cutout of this invention.
~IGURE 8 compares thickness data at various locations on SPF parts made using prior art techniques and using the techniques of this ~nvention.
Figure 9A shows an orthogonal projection of one-half of a SPF part.
Figure 9B shows a method for manipulatingdie surfaces to arrive at the size of a cutout of this invention.
FIGURE 9C illustrates a plan view of the blank after manipulating and projecting the die surfaces of Figure 9B.
Description of the Preferred Embodiment One of the greatest chaUenges associated with Superplastic Forming is predicting m~t~,ri~l thinout and then achieving that thinout duling part f~hric~tion. The m~teri~l thinout challenge is inherent to the SPF process and stems from varying m~te,ri~l thickness across the part area after SPF. Engineering drawings typically call out a minimllm allowed m~t~ l thickness across the entire part or in specific regions of the part.
The reason that material does not thinout uniformly is that once the lid is closed on the SPF die, the periphery of the material is restrained such that the material is not allowed to "draw-in" from the edges. As a result, the m~t~ri~l that will become the part area must be stretched from the material inside of the seal area.
During forming, the stretching of the material within the seal area progresses until the m~t~ l eventually contacts the die sur~ace. Upon contact, the mz~t~ l sticks to the die sur~ace. The remaining m~teri~l that has not yet contacted the die continues to stretch until it too contacts the die surface and sticks. Once the material is completely formed, the thinnest regions are generally those that are the last to form. These regions equate to the deepest areas of the die and radii, in particular spherical radii (corners).
Since material thinout is dependent on the die geometry, the die design is ~ritical in achieving the proper material thinout. Of specific importance is the die "run-out", which - is the die region outside the net part area. A correctly designed die will optimize the "run-out" configuration so that thinout is minimi7~d in the part area and maximized in the "run-out" material.
Once the part area and "run-out" of the die have been machined and the first SPF part is formed, there are only a few options for recouTse if the part is too thin according to engineering drawing requirements. The two most common options are: (1) Start with a thicker gauge of blank m~t~,ri~l, (2) Preform the blank prior to forming it into the final part configuration.
The former option is the easier of the two options to irnplement and provides relatively quick results for thickness analysis. However, it is not a ~ua~ ee for achieving the correct minimnm thickness since adding thickness to the starting blank does not equate to a sufficient thickness increase in the thinnest areas of the part. Furthermore, an increase in the starting m~t~,ri7l1 gauge adversely effects the part weight.
. CA 02221076 1997-11-14 The latter option, designing a prefor n for the blank, carries a fair amount of risk.
Designing a successful preform geometry potentially requires several iterations, an expensive and tinne consuming process. As with increasing the material gauge, preforming will not guarantee a successful part.
With this invention a third option becomes available for selectively increasing the material thickness in specific regions of the part. This option too, does not guarantee that the minimum material thinout will be attained. However, through a combination of increasing the starting gauge and utilizing this third option, the odds of attaining a successful part are significantly increased.
Depending on the part configuration, it is possible to minimi7e the material thinout by placing a strategically located cutout(s) in the starting blank. The typical applicable part configuration is one that has an area of the net trim that is in~f~rn~l to the part itself (i.e. a pocket or "bowl"). A simplified example would be a pan-shaped part that has the bottom of the pan cut away, resulting in a ring-shaped part.
Cutting out a hole(s) in the material allows for the hole(s) to enlarge as the m~t~ ri~l is stretched onto the tool surface. This enlarging takes the place of stretching and thinning the material if the holes were not present. The basic concept is that the hole enables more axial stretching of the material and minimi7e~ the biaxial stretching (ref.Figure ~. The end result is minimi7ed material thinout in the axially stretched material. The thinout in areas of the hole that are stretched biaxially is also minimized (relative to not using the cutout(s), but to a lesser extent than the axially stretched regions (ref. Figure 6 and Data Table I).
Since the SPF process uses gas pressure to form the m~t~n~l, it is imperative that the sheet being formed does not have any holes through it. This requirement is in direct opposition to the process of this invention. Subsequently, a second sheet of material that does not contain any cutout locations, is required to form the blank (material with the cutout(s). This second sheet is placed between the blank and the die lid and becomes the membrane which can be pressurized and formed onto the tool geometry. While forming, this secondary sheet also forms the blank with the cutout(s). Once the blank is fully formed (die surface is in intimate contact with the entire blank), the blank and secondary sheet are separated and the secondary sheet is discarded There are three critical factors-that must be dealt with to successfully utilize the disclosed process. Those factors are: (1) l_ocation of cutout(s) on the blank, (2) Shape and Size of the cutout(s) on the blank, and (3) Indexing the blank to the tool.
Cutout Location: The location of the cutout(s) is op~ ized when the periphery of the cutout(s) is located as close as possible to the net trim of the part after forming. Locating the cutout(s) as such will maximize the m~t~ thickness at the trim line.
Shape and Size of the Cutout(s): The cutout(s) shape and size are critical in that an un~ler~i7ed cutout will result in unnecessary thinout. Conversely, an oversized cutout will result in undercutting the trim line of the part. While both sizing and locating the cutout(s), caution must be taken so that the formed blank does not become entrapped by the secondary sheet during the separation of the two sheets (ref. Figure 6B).
. CA 02221076 1997-11-14 There are several methods for deter~rlining the proper location and size of the cutout(s) on the blanks. Besides trial and error, a highly accurate "best guess" can be made utilizing a model of the die surface. Among the most easily manipulated mode is a Computer Aided Drafting (CAD) model. Once generated, the tool surfaces can be projected or rotated to one plane so that the trim line of the part can be seen on that plane - the equivalent of a forming blank (ref. Figure 9). ~his planar trim line de~lnes a preliminary location, si~, and shape of the cutout(s). The ~mal size and shape of the cutout can then be obtained by applying a reduction factor anad corner radii to the preliminary size and shape.
Indexing the Blanlc to the Tool: Once the size, shape, and location of the cutout(s) have been detennined, it is paramount that the blank be located to the die accurately. Without accurate, repeatable alignment, it is not possible to produce a consistent part. One method of locating the blank to the die is through the use of "pins~' or "posts" that extend from the die sealing surface. Holes can then be cut into the blank and secondary sheet tocorrespond to the pins in the die.
Description of Figures:
Figure 5: Illustrates the process steps for the Disclosed Invention Prior to Figure 5A, the region(s) of the blank that are to be cutout must be removed. The location, size and geometry of the cutout(s) is of critical importance for the successful forming of the part. In addition, it is also critical that the blank be indexed to the die surface so that the cutout area(s) form into the desired areas of the die.
Figure 5A: This figure illustrates the die, die lid, material blank and the secondary sheet. Once the die is heated to the forming temperature for the particular material . . CA 02221076 1997-11-14 alloy, the blank and secondaIy sheet are placed on the surface of the die. The location of the secondary sheet is between the die lid and the blank.
Figure 5B: The blank and secondary sheet are "sandwiched" between the die and lid by means of a force applied to the lid.
Figure 5C: As gas pressure is introduced to the top side of the secondary sheet,the secondary sheet and blank are formed into the die cavity.
Figure SD: Forming continues as the gas pressure is increased.
Figure 51~: Upon completion of the forrning cycle, the blank is in full contact with the die surfaces.
Figure 5F: The gas pressure is vented and the lid is removed. The blank and secondaly sheet are separated and removed from the die.
Figure 6A: This figure illustrates the result of correctly calculating and locating the cutout(s) on the blank. In this instance, the secondary sheet does not entrap the blank when the two are separated.
Figure 6B: This figure illustrates the potential problem of material entrapment caused by incorrectly calculating the size and location of the cutout(s) on the blank. In this instance after forming, the edge of the cutout(s) became located on a near-vertical surface, creating entrapment of the blank by the secondary sheet.
This entrapment does not allow for separation of the blank and secondary sheet without cutting the two apart~
. CA 02221076 1997-11-14 Figure 7: This figure illustrates the types of stretching of the cutout periphery that take place during forming of the blank. Any straight line regions of the cutout periphery will undergo stretching in one direction ~axial). (~urved segments of the cutout will stretch in two directions (biaxial). In general, the axial stretching that takes place will result in less thinout' than in the regions that are biaxially stretched.
Figure 8: This figure illustrates data obtained from fabricated test parts. All parts started with the same material thickness and were measured in the same locations.
From the data it is possible to see that by cutting hole(s) in the blank, it is possible to achieve a 69% increase in as-formed material thickness, in comparison to parts formed without the invention process.
Figure 9: This ~lgure illustrates how the basic geometry and location of the cutout(s) can be obtained. This key information be obtained through several methods. However, the easiest method is through the manipulation of Computer Aided Drafting (CAD) data of the die geometry. Use of such data is illustrated in this ~lgure.
Figure 9A: This figure illustrates half of a symmetrical part. The dashed lines indicate surfaces of the die.
Figure 9B. This figure shows the axis about which the surfaces are rotated. Oncethe surfaces are rotated to the starting plane, a preliminary outline of the cutout can be determined. The edge of the surface rotated is determined by the net trim of the part.
Claims (7)
1. An improved method of forming a metal part by superplastic forming using a die, a pressurized gas, and a blank sheet of metal from which said part is made; said improvement comprising locating a secondary sheet in contact with said blank and also in contact with said pressurized gas: making a cutout in said blank to obtain thicker part material in specific locations when the pressurized gas is applied for an appropriate cycle time.
2. The method of claim 1 wherein said cutout is sized and located to minimize material thinout.
3. The method of claim 2 wherein said cutout is sized and located to increase in size when pressurized gas is applied for an appropriate cycle time.
4. An improved method of forming a metal part by superplastic forming in which die surfaces 1,2, and 3 outline the apaproximate location and size of cutouts by manipulation of Computer Aided Drafting (CAD) data of the die geometry.
5. An improved method of achieving thicker part material in predetermined regions of the Superplastic formed detail through the use of a blank with preselected cutout areas and is then formed onto the die surface by the secondary sheet, which does not contain any cutouts.
6. The method of claims wherein the part blank is aligned to die and other associated apparatus such that the periphery of the cut-away aarea of the blank falls into a specific location of the tool surface.
7. The method of claim 5 determines that cutout geometry and cutout location on the blank material, wherein the surfaces are rotated into the starting plane.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US77372896A | 1996-12-21 | 1996-12-21 | |
| US08/773,728 | 1996-12-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2221076A1 true CA2221076A1 (en) | 1998-06-21 |
Family
ID=25099138
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002221076A Abandoned CA2221076A1 (en) | 1996-12-21 | 1997-11-14 | Advanced forming techniques for superplastic forming |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0849013B1 (en) |
| CA (1) | CA2221076A1 (en) |
| DE (1) | DE69704541T2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108372250B (en) * | 2016-12-20 | 2019-12-06 | 中国航空制造技术研究院 | control method for superplastic forming process |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4748837A (en) * | 1985-12-11 | 1988-06-07 | Hitachi, Ltd. | Method of forming spherical shells |
| US4984348A (en) * | 1989-01-17 | 1991-01-15 | Rohr Industries, Inc. | Superplastic drape forming |
| US5419170A (en) * | 1993-10-15 | 1995-05-30 | The Boeing Company | Gas control for superplastic forming |
-
1997
- 1997-11-14 DE DE69704541T patent/DE69704541T2/en not_active Expired - Fee Related
- 1997-11-14 EP EP97203563A patent/EP0849013B1/en not_active Expired - Lifetime
- 1997-11-14 CA CA002221076A patent/CA2221076A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| EP0849013A1 (en) | 1998-06-24 |
| EP0849013B1 (en) | 2001-04-11 |
| DE69704541D1 (en) | 2001-05-17 |
| DE69704541T2 (en) | 2001-08-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |