Patent Application
20150114063
The present disclosure relates to hydroforming process of a hollow blank, and more particularly to a system and a method of forming a hole in the hollow blank during the hydroforming process.
Conventional method of cold forming metal tubes to create structural members, for example, for the automotive industry, is hydroforming. In a typical hydroforming process, a metallic sheet and/or metal hollow tube is partially deformed by stamping it in a hydroforming die element. Then, internal hydraulic pressure exceeding the yield strength of the tube wall is applied to force the tube to expand and conform to the die cavity.
After either the hydroforming process or the liquid impact forming process, holes are typically pierced or punched into the structural tube, for example, to provide points of attachment. Typically, punching holes deforms the metal surrounding the hole.
U.S. Pat. No. 7,552,535 relates to a method for manufacturing a hydroforming member includes the step of providing a blank. The blank is defined by blank wall. The blank is placed in a die assembly having a die cavity defined by a die surface. The blank is expanded so that the blank wall is forced against the die surface to form the hydroformed member. A portion of the blank wall conforms against a wall-thinning element positioned along the die surface to form a removable wall section in a portion of the blank wall. The removable wall section is then removed from the blank wall to form an opening in the hydroformed member in a separate die and process.
In one aspect of the present disclosure, A method of forming a hole in a hollow blank during a hydroforming process is provided. The method includes placing a blank in a cavity of a hydroforming die, the hydroforming die being configured to permit a punch to engage the blank. An interior of the blank is pressurized with a fluid. Further, a cutting end of a punch is applied through a wall portion of the blank and into the interior of the blank to form a hole. Furthermore, the cutting end of the punch is removed from the interior of the blank such that the cutting end of the punch is configured to allow material of the blank surrounding the formed hole to move away from the interior of the blank.
In another aspect of the present disclosure, a method of piercing a hole in a wall of a tube during a hydroforming process is provided. A blank is placed in a cavity of a hydroforming die. The hydroforming die is configured to permit a punch to engage the blank. An interior of the blank is pressurized with a fluid. Further, a cutting end of a punch is applied through a wall portion of the blank and into the interior of the blank to form a hole. A portion of the cutting end of the punch has a groove circumferentially disposed about the punch, material surrounding the hole being displaced from its original position by an initial displacement and then allowed to be displaced within the groove to an intermediate displacement closer to its original position. Further, the cutting end of the punch is removed from the interior of the blank, wherein a first surface forming the groove is capable of engaging the material surrounding the hole away from the intermediate displacement to a final displacement.
In a yet another aspect of the present disclosure, a punch for piercing a hole in a blank during a hydroforming process is provided. The punch includes a shank portion and a cutting end provided on the shank portion. The cutting end is configured to form a hole in the blank. Further, the punch includes a reduced cross-sectional area disposed about an outer surface of the punch and adjacent to the cutting end. The reduced cross-sectional area is configured to allow material of the blank surrounding the formed hole to move away from the interior of the blank.
Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.
The present disclosure relates to a system and method of forming a hole in a hollow blank during a hydroforming process.
The system 100 may include multiple die elements, such as, an upper hydroforming die element 104 and a lower hydroforming die element 106 having a cavity 108. The blank 102 is placed between the hydroforming die elements 104 and 106 of the system 100. The blank 102 may have open ends (not shown) such that one of the open ends of the blank 102 may be selectively sealed, while the other end remains selectively open to facilitate filling of a fluid 112 within the blank 102 to pressurize an interior of the blank 102. In an exemplary embodiment of the present disclosure, the fluid 112 may be a readily available, inexpensive and non-harmful fluid such as water. In various alternate embodiments, the fluid 112 may include additives such as lubricants, bactericides, rust preventives, or other additives known in the art. Once the blank 102 is filled with the pressurized fluid 112, the other end of the blank 102 may be also sealed. In an exemplary aspect of the present disclosure, the blank 102 is sealed at both the ends by attaching caps (not shown) to both the open ends of the blank 102 such that the caps form a pressure tight seal that can withstand elevated pressures to which the interior of the blank 102 is subjected to during the hydroforming process.
As shown in
In an aspect of the present disclosure, the system 100 includes a hydroforming punch 114 configured to engage the blank 102, and stamp and/or form a hole 116 in the blank 102, as shown in
Subsequently, the hydroforming punch 114 is removed from the blank 102 after the stamping and/or piercing process during the hydroforming process performed by the system 100, as shown in
In an aspect of the present disclosure, the punch 114, as illustrated in
In an exemplary aspect of the present disclosure, the cutting end 508 of the punch 114 may include a reduced cross-sectional portion 510. For example, the reduced cross sectional portion 510 may be formed by a groove, hereinafter referred to as the groove 510, circumferentially disposed about the cutting end 508 of the punch 114. The groove 510 may include at least one of a first surface 512 and a second surface 514, as shown in
When the hole 116 is formed on the blank 102 by the punch 114, then the material surrounding the formed hole 116 tends to move towards the inner surface 502 of the blank 102 to an initial displacement away towards the cavity 108 and away from the original position. In an aspect of the present disclosure, the groove 510 disposed on the cutting end 508 allows the material surrounding the formed hole 116 to rest within the groove 510. For example, pressure of the fluid 112 filled within the blank 102 displaces the material of the blank 102 away from the initial displacement into the reduced cross-sectional area 510 to an intermediate displacement. In an alternative embodiment, a spring back performance of the material, may cause the material of the blank 102 surrounding the hole 116 to spring back from the cavity 108 into the reduced cross-sectional area 510 to the intermediate displacement. The intermediate displacement may be closer to the original position than the initial displacement. Further, the first surface 512 may face away from the inner surface 502 of the blank 102. Therefore, while removing the punch 114 from the blank cavity 108 in a withdrawal direction (opposite than the arrow shown in
Moreover, in an alternative aspect of the present disclosure, the groove 510 may cause the material of the blank 102 surrounding the hole 116 to be pulled back further from the final displacement and beyond the original position towards the cavity 108, as shown in
In an exemplary embodiment, the cutting end 704 of the punch 700 includes a stepped cross-sectional profile, such that a first diameter D1 of the cutting end 704 is less than a second diameter D2 of the shank portion 702. For example, the cutting end 704 is stepped to the larger diameter shank portion 702, as shown in
In an aspect of the present disclosure, the cutting end 804 of the punch 800 includes a scalloped top 806, having a plurality of curved projections 808, as shown in
In an aspect of the present disclosure, the punch 1000 includes an engagement end 1002 provided on a shank portion 1004, such that the engagement end 1002 engages with the outer surface 504 of the blank 102 while the blank 102 is under pressure during the hydroforming process. The punch 1000 then creates a coined impression on the wall portion 501 of the blank 102. In this case, the punch 1000 does not penetrate through the wall portion 501 of the blank 102 to form the hole 116, but it simply creates a coined impression on the blank 102. Subsequently, the punch 1000 is extracted out of the cavity 108.
The industrial applicability of the system 100 having the punches 114, 500, 700, 800, 1000 and 1100, described herein will be readily appreciated from the foregoing discussion.
The present disclosure discloses a punch 114 which is used in forming a hole 116 in the hollow blank 102. The groove 510 disposed on the cutting end 508 of the punch 114 allows the material around the formed hole 116 to be pulled back to the original position. Additionally, maintaining the gap 113 between the lower hydroforming die element 106 and the blank 102 allows the material of the blank 102 to deform towards the cavity 108 prior to punch 114 engaging. As the punch 114 would deform the material of the blank 102 around the hole 116 towards the centre of the blank 102, the deformation of the material that was done prior to the punch 114 engagement may neutralize the deformation of the material around the hole 116 after the punch 114 engagement in an opposite direction. Therefore, there may be zero or minimum deformation of the material of the blank 102. Further, the punch 114 of the present disclosure prevents the permanent deformation of the material of the blank 102 surrounding the formed hole 116. The punch and method may be particularly useful for tubes having a thickness of greater than or equal to 3 mm. At such thicknesses, material may be difficult to punch and often results in permanent deformation of the material of the tube surrounding the formed hole. The punch and method may minimize the severity of the deformation surrounding the holes to make punching in heavy wall tubes possible with minimal permanent deformation. Such holes may be used to mount other components or parts to the tubes when employed as structural ROPS tubes or for fixturing the part for further assembly processing.
Further, the cutting end 704 of the punch 700 provides a controlled desired deformation, such as coining of the material of the blank 102 around the formed hole 116. Furthermore, the cutting end 804 of the punch 800 of the present disclosure provides a clean formation of the hole 116 and minimizes the permanent deformation of the material of the blank 102 around the formed hole 116.
In an aspect of the present disclosure, the punches 1000 and 1100 provide stamping of the blank 102. The engagement end 1002 of the punch 1000 creates the coined surface on the blank 102 which allows flush mounting of assembled components such as rivets, nut heads, hinge flanges etc. Further, the engagement end 1102 of the punch 1100 creates a conical protrusion on the inner surface 502 of the blank 102. This conical protrusion allows locating features near that area of the blank 102 or locating a part in a larger assembly to which the blank 102 is a part.
With additional reference to
Further, at step 1204, the engagement end such as the cutting end 508 of the punch 114 may be applied through the wall portion 501 of the blank 102 and into the inner surface 502 of the blank 102. For example, the punch 114 may be moved at a sufficient force, speed, and distance to penetrate the wall portion of the tube, such as by a hydraulic press. The cutting end 508 of the punch 114 may pierce the wall portion 501 of the blank 102, such as shown in
Furthermore, at step 1206, the punch 114 may be withdrawn from the blank 102. In one example, the punch 114 may be withdrawn from the blank cavity 108, as shown in
While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.
