KR20020086557A - Hydroforming flush system - Google Patents

Abstract

The hydraulic molding assembly 10 has a plurality of die structures 20, 21 mountable on the press for reciprocating motion between open and closed conditions. The die structures have a cooperating die surface 22 defining the die cavity 23 when in the closed condition and receive the metal tube blank 24 when in the open condition. The hydraulically molded fluid supply system has a tube-end coupling structure 25 that is movable to selectively and sealably engage opposite ends of the tube blank. The hydraulic molding fluid supply system provides pressurized fluid into the tube blank 24 to expand the tube blank outward in conformity with the die cavity 23. The punch 52 extends in the passage 51 of at least one of the die structures. The punch 52 is movable between the retracted position and the extended position. The punch drive assembly 54 drives the punch between the retracted position and the extended position to drill a hole in the expanded tube blank. The flushing system 30 is in communication with the die cavity 23 to provide a flushing fluid flow through the interior of the tube blank.

Description

Hydraulic Molding Flush System {HYDROFORMING FLUSH SYSTEM}

In recent years, hydraulic molding technology has become increasingly important in the manufacturing industry, especially in the automobile industry. In one application of hydraulic forming, a tubular metal blank (usually steel) is located in the die cavity. Opposite ends of the tube are sealed by a pair of hydraulic rams having a center port through which a very high pressure fluid is injected into the tube. The high pressure fluid expands the tube against the surface defining the cavity. As a result of this hydroforming process, high strength parts can be produced in complex tubular shapes that could not be achieved in any practical and economic way. Such hydroforming processes are disclosed in US Pat. Nos. 4,567,743, 5,070,717, 5,107,693, 5,233,854, 5,239,852, 5,333,755 and 5,339,667.

Even in advanced forms of hydroforming, hydraulic rams are forced inwards toward each other to produce metal flow in the tubes as the tubes expand to maintain the wall thickness of the tubes within a predetermined range throughout the expansion process. Such hydroforming processes are disclosed in US Pat. Nos. 5,718,048, 5,855,394, 5,899,498, 5,979,201 and 5,987,950.

For some applications, it is desirable to manufacture a finished part having a plurality of holes that can be used to mount other components. For example, it is known to hydroform tubular blanks to form engine cradle assemblies used to mount automotive engines in the automotive industry. The finished tubular part shall be provided with a hole through which the fastener can pass in order to mount an engine mounting bracket or the like. In order to facilitate providing a hole in the part, it is known to perform a hole piercing operation within the hydraulic die itself. Typically, a hole is drilled through the tube under pressure. In one method, a portion of the tube cut by the punch (often referred to as "slug") has an edge portion connected to the tube and suspended in the tube. This is a problem because it adds unnecessary weight to the components, which is always a concern in the automotive industry. In another method, the punch is retracted from the tube after the hole is formed, and the hole formed by the punch remains engaged with the punch at the force of the fluid pressure when the punch is retracted from the tube. The slug then flows to the debris collector by the fluid. One such conventional work is disclosed in US Pat. No. 5,816,089. One problem associated with the techniques described above is that slugs are often not aligned correctly in the holes resulting therefrom when the punch is retracted and can fall into the tube. It must then be recovered by other means.

The present invention relates to a system for removing fluid from the inside of a part by flowing a fluid through a hydraulically molded part.

1 is a schematic cross-sectional view of a hydraulic molding apparatus having a slug separation system and in-die hydraulic piercing in accordance with the principles of the present invention, showing a tubular metal blank inserted into the hydraulic molding apparatus in preparation for hydraulic molding; do.

Figure 2 is similar to Figure 1 but shows the expanded metal tube after hydroforming.

FIG. 3 is a partially enlarged view of the hydroforming apparatus shown in FIG. 2 providing a detailed view of the hydraulic piercing punch assembly in a position where the punch is retracted.

FIG. 4 is similar to FIG. 2 but shows the punch in the extended position after punching in the expanded metal tube.

FIG. 5 is a partial enlarged view similar to FIG. 3 but showing the punch in the extended position after punching in the expanded metal tube; FIG.

FIG. 6 is similar to FIG. 4 but shows the perforated slug flows out of the expanded metal tube.

It is an object of the present invention to provide a means for removing debris from the interior of a hydraulically molded part.

Accordingly, the present invention provides a hydroforming assembly having a plurality of die structures mountable on a press for reciprocating motion between open and closed conditions. The die structures have a cooperating die surface that defines the die cavity when in the closed condition and receive the metal tube blank when in the open condition. The hydraulically molded fluid supply system has a tube-end coupling structure that is movable to selectively and sealably engage opposite ends of the tube blank. The hydraulic molding fluid supply system provides fluid pressurized into the tube blank to expand the tube blank outward in conformity with the die cavity. The punch extends in the passage of at least one of the die structures. The punch is movable between the retracted position and the extended position. The punch drive assembly drives the punch between the retracted position and the extended position to drill a hole in the expanded tube blank. The flushing system is in communication with the die cavity to provide a flushing fluid flow through the interior of the tube blank.

In accordance with another aspect of the present invention, a method is provided for forming a hole in a hydraulically molded metal tube blank and removing perforated debris therefrom. A plurality of die structures are provided on the press for reciprocating motion between open and closed conditions. Die structures have a cooperating die surface that defines the die cavity when in closed condition. Die structures are provided in open conditions. The metal tube blank is placed into the die cavity. The die structures are closed. The interior of the tube blank is pressurized to allow the tube blank to expand in conformity with the die cavity and thus form an expanded tube blank. The punch is forced through the expanded tube blank to drill holes in the tube blank. The interior of the expanded tube blank is depressurized. The fluid flows through the expanded tube blank to cause the perforated portion of the expanded tube blank to flow out of the interior of the expanded tube blank.

Referring now to the drawings in particular, a schematic cross-sectional view of a hydroforming apparatus, indicated generally at 10, embodies the principles of the invention. The hydraulic forming apparatus 10 comprises a hydraulic press, typically designated 12, having an upper support structure 14, a lower support structure 16 and a vertical support structure 18. The hydraulic forming apparatus 10 is provided with a cooperative die structure, which may include an upper die structure 20 and a lower die structure 21. The upper die structure 20 may be raised and lowered such that the die structures 20, 21 are movable between the open and closed positions. Die structures 20, 21 are shown in the closed position in FIG. 1. Dies 20, 21 provide a die surface 22 that defines a sealed die cavity 23 when the dies 20, 21 are in the closed position. The shape and dimensions of the die cavity 23 are configured to form the desired shape and dimensions of the part to be hydroformed. 1 shows a tubular metal blank 24 positioned within a die cavity 23 to be hydraulically molded. Opposite ends of the tubular metal blank 24 are sealingly engaged by a pair of hydraulic tube-end coupling structures or “hydraulic rams” 25 that are driven by the hydraulic actuator 26 and moveable to the changed position. Each of the rams 25 has a central port 27 through which very high pressure hydraulic fluid (eg, about 10,000 atmospheres) is injected into the tubular metal blank 24.

A reciprocating hydraulic piercing punch assembly, designated generally 50 in detail in FIG. 3, is incorporated into at least one of the die assemblies 20, 21.

The hydraulic molding apparatus 10 is equipped with a flushing fluid system, generally designated 30, in communication with the die cavity 23. The flushing fluid system 30 is used to remove at least one perforated portion or “slug” 86 of the expanded metal tube 24 (as shown in FIG. 4). The flushing fluid system 30 includes a flushing fluid inlet port 32 located at one end of the die cavity 23 and a flushing fluid outlet port 33 located at an opposite end of the die cavity 23. Preferably, both of these ports 32, 33 are formed in the lower die structure 21 as shown. Flushing fluid system 30 preferably includes a debris separator, typically designated 34 with a mesh or screen 36. The flushing fluid system also preferably includes a fluid reservoir 38 that can be used to store and / or recycle the flushing fluid, if desired. The flushing fluid system 30 also includes a circulator 40 and a connecting tubing line 42 for circulating the flushing fluid through the flushing fluid system 30.

Referring now to FIG. 3, a hydraulic piercing punch assembly 50 is shown in more detail. Punch assembly 50 is used to drill holes 84 (as shown in FIG. 4) in expanded metal tube 24. Any number of similarly designed punch assemblies 50 can be incorporated into one or more die structure (s) 20, 21. The punch assembly 50 includes a punch receiving passage 51, which is incorporated into the die structure (s) through which the punch 52 can be moved between a retracted and extended position. The punch 52 is movable in a slidable and sealed relationship with respect to the passage 51 by the annular sealing member 53. Punch assembly 50 includes a punch driver assembly, generally designated 54, used to drive punch 52 between a retracted position and an extended position. In the retracted position, the distal surface 55 of the punch 52 is flush with the die surface 22 and helps to define the die cavity 23. Punch driver assembly 54 includes punch driver 56 connected to punch piston 58, which may be a hydraulic cylinder. The base end 59 of the punch 52 is fixed to and connected to the punch piston 58. The punch piston 58 is movable between the retracted position and the extended position. The punch 52 traverses through the opening 62 in the punch driver housing 60 in a slidable relationship with respect to the opening 62.

The flushing fluid system 30 may include a slug separation system, generally designated 70, which may provide a means for separating the slug 86 from the end working surface 55 of the punch 52. At least one of the die structures 20, 21 is mounted to the slug separating fluid septum 72. The peripheral seal 74 between the die structures 20, 21 and the partition wall 72 surrounds the slug separation system 70 so that the slug separation system 70 can be sealed from the atmosphere and pressurized by the slug separation fluid. All. The slug separation system 70 includes a slug separation fluid input port 76 located on the slug separation fluid partition 72. The slug separation fluid input port 76 may be connected to any suitable high pressure pump that provides pressurized slug separation fluid to the slug separation system 70. The slug separating fluid input port 76 is connected to a slug separating fluid passage 78, which may be common with some punch assemblies 50. The passageway 78 may be a groove of any suitable dimension formed in the die structure (s) 20, 21. Passage 78 communicates with a slug separating fluid pressure chamber 79 that may be formed in die structure (s) 20, 21. The punch 52 includes a slug separating fluid port 80 that traverses longitudinally through the punch 52. The slug separating fluid port 80 begins at the slug separating fluid inlet 82 located on the side of the punch 52 and ends at the outlet 83 at the punch working surface 55. The slug separation fluid inlet 82 may be positioned to communicate with the slug separation fluid pressure chamber 79 when the punch 52 is in an extended position such that the slug separation fluid port 80 may be pressurized with the slug separation fluid. .

The operation of the hydraulic molding apparatus 10 will now be described. Referring to FIG. 2, the metal tube 24 corresponds to the inner surface 22 of the die cavity 23 and engages the working surface 55 of the punch 52 in the retracted position at hydraulic fluid pressure. Swell. In order to maintain the desired wall thickness of the expanded metal tube 24, as the tube 24 is inflated, the hydraulic rams 25 are forced inwards toward each other to produce metal flow in the tube 24.

In Fig. 4, the punch driver or cylinder 56 is actuated to drive the punch piston 58 to the extended position. This operation drives the punch 52 into the extended position from the retracted position after the metal tube 24 has expanded in correspondence with the die surface 22, thus openings 84 in the expanded metal tube 24. The punch 52 is forced through the expanded metal tube 24 to drill through and form the slug 86. The hydraulic fluid is expanded to support the interior of the tube 24 during the drilling operation to prevent deformation of the expanded metal tube 24 by the punch 52 in the region adjacent the perforated hole 84. High pressure is maintained in the metal tube 24. The die structures 20, 21 remain in the closed position, and the expanded metal tube 24 maintains engagement with the surface 22 of the die cavity 23. In the extended position, the punch 52 serves to seal the perforated holes 84 in the tube 24, thus restraining fluid from the tube 24 during subsequent slug flushing operations. To help maintain fluid within

5 shows the punch 52 in the extended position in detail. The slug separation fluid inlet 82 communicates with the slug separation fluid pressure chamber 79, thereby allowing the slug separation fluid to flow through the slug separation fluid port 80.

Referring now to FIG. 6, at least one of the hydraulic rams 25, ie at least the ram adjacent to the outlet port 33, but preferably all of the rams, is hermetically engaged with the end (s) of the expanded metal tube 24. Is movable from, thereby causing the hydraulic fluid in the tube 24 to be depressurized. The hydraulic ram 25 is now positioned to facilitate the flow of flushing fluid and to remove the slug 86 from the tube 24. The die structures 20, 21 are maintained in a closed position and the flushing fluid system 30 is in communication with the die cavity 23 to allow the flushing fluid to flow into the expanded metal tube 24.

Typically, the slug 86 will remain engaged to the end working surface 55 of the punch 52. If this is the case, the present invention provides various means to separate the slug 86 from the end working surface 55 of the punch 52.

In one embodiment, the slug 86 forces the fluid through the fluid port 80 and presses the slug separation system 70 by forcing the slug separation system 70 to separate the slug 86 from the working surface 55 of the punch 52. 52 may be forcibly separated from the end surface 55 of 52. Alternatively, punch driver 56 may be used to rapidly reciprocate punch 52 to separate slug 86 from working surface 55 of punch 52.

In another embodiment, the slug 86 may be forced off the end working surface 55 of the punch 52 only by the rapid flow of the flushing fluid through the tube 24 as provided by the flushing fluid system 30. Can be.

Flushing fluid circulator 40 and connecting tubing line 42 allow the separated metal slug 86 to flow through the expanded metal tube 24 and at a sufficiently high flow rate to remove the slug 86 from the tube 24. Provide a flushing fluid. The flushing fluid flows through the inlet port 32 and passes through the tube 24 to carry the slug 86 outward through the opposite end and the outlet port 33 of the tube 24. The outlet port 33 and the connecting tubing line 42 are of appropriate dimensions with a sufficiently large inner diameter so as not to block the flow of the slug 86 and the flushing fluid from the die 21. Once the metal slug 86 is removed from the die 21, the slug 86 can be separated from the flushing fluid by a mesh or screen 36 in the debris separator 34, and the fluid is withdrawn into the fluid reservoir 38. Can be. During the flushing fluid operation, the punch 52 is maintained in an extended position to prevent leakage of the flushing fluid through the apertures 84 drilled in the tube 24.

Although the invention has been shown and described in detail in the drawings and foregoing description, it is to be understood that the invention is illustrative and not restrictive in nature, that the preferred embodiments are shown and described, and that all modifications and variations are within the scope of the appended claims. It is understood that.

Claims (16)

A plurality of die structures that are mountable on the press for reciprocating motion between open and closed conditions, have a cooperative die surface defining a die cavity when in closed condition, and receive metal tube blanks when in open condition; A tube-end mating structure that is movable to selectively and sealingly engage opposite ends of the tube blank and is pressurized into the interior of the tube blank to inflate the tube blank outward with expanded conditions in accordance with the die cavity A hydraulic molding fluid supply system for providing a fluid, A punch extending within the passageway of at least one of the die structures and movable between the retracted position and the extended position; A punch drive assembly operatively connected with the punch to drive the punch between a retracted position and an extended position to drill a hole in the tube blank after the tube blank is expanded in an expanded condition; And a flushing system in communication with the die cavity to provide a flushing fluid flow through the interior of the tube blank. 2. The punch of claim 1 wherein the punch has a work surface that is coplanar with the die surface of the die cavity when the punch is in the retracted position and the work surface into the die cavity when in the extended position. Hydraulic molding assembly, characterized in that extending. 3. The press of claim 2, wherein the punch has a fluid passageway in communication with the working surface of the punch, the fluid passage being pressurized which can be discharged through the fluid passageway to press the perforated portion of the tube blank away from the working surface of the punch. A hydraulic molding assembly in communication with a source of fluid. 4. The hydraulic molding assembly of claim 3 wherein the fluid passageway communicates with a source of pressurized fluid when the punch is in the extended position. 5. The hydraulic molding assembly of claim 4, wherein the punch drive assembly includes a housing having an opening, wherein the punch extends through the opening. 6. The interior of the housing of claim 5 wherein the interior of the housing is isolated from a source of pressurized fluid, the fluid passageway communicating with the interior of the housing when the punch is in the retracted position and the exterior of the housing when the punch is in the extended position. Hydraulic molding assembly having an inlet positioned to be positioned. 7. The hydraulic molding assembly of claim 6 wherein the pressurized fluid is a gas. 2. The hydraulic molding assembly of claim 1, wherein the punch is maintained in an extended position during the flow of flushing fluid. The hydraulic molding assembly of claim 1, wherein the punch reciprocates during the flow of flushing fluid. The hydraulic molding assembly of claim 1, wherein the tube-end coupling structure retracts from engagement with the ends of the tube blank to initiate communication of the interior of the tube blank with the flushing system. 2. The flushing system of claim 1, wherein the flushing system comprises a debris separator for receiving flushing fluid flow from the die cavity, a fluid reservoir providing a source of fluid for the flushing fluid flow, and a circulator for performing the flushing flow. Hydraulic molding assembly. A method of forming a hole in a hydraulically molded metal tube blank and removing perforated debris therefrom, Providing a plurality of die structures that are mountable on a press to provide reciprocating motion between open and closed conditions, have a cooperative die surface defining a die cavity when in a closed condition, and in open conditions; Positioning a metal tube blank into the die cavity; Closing the die structure, Pressurizing the interior of the tube blank such that the tube blank expands in conformity with the die cavity and thus forms an expanded tube blank; Forcing a punch through the tube blank to drill a hole in the expanded tube blank; Depressurizing the interior of the expanded tube blank; Flowing fluid through the expanded tube blank to cause the perforated portion of the expanded tube blank to flow out of the interior of the expanded tube blank. The method of claim 12, wherein the punch has a fluid passageway in communication with the working surface of the punch, and the method provides pressurized fluid through the fluid passageway to press the perforated portion of the expanded tube blank away from the working surface of the punch. The method comprising the step of. 13. The method of claim 12, wherein the method comprises reciprocating the punch during the flowing of the fluid. 13. The method of claim 12, wherein depressurizing comprises initiating communication of the flushing system with the interior of the expanded tube blank. 13. The method of claim 12, wherein the punch is maintained in an extended position extending into the expanded tubular blank during the step of flowing the fluid.