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
  • B21D26/06—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 by shock waves
  • B21D26/12—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 by shock waves initiated by spark discharge
• • 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
• • 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
  • B21D26/06—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 by shock waves
• • 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
  • B21D26/021—Deforming sheet bodies
  • B21D26/027—Means for controlling fluid parameters, e.g. pressure or temperature

Definitions

• the present invention relates to a chamber for electro-hydroforming device.
• Electro-hydroforming devices are increasingly used for the production of mechanical parts. Indeed, this forming technology makes it possible to obtain pieces of relatively complex appearance while controlling production costs. For example, the automotive and aerospace industries use such technologies.
• a hydroforming process is a process of manufacture by deformation. It allows the plastic deformation of a metal part of a relatively small thickness. To achieve this deformation, a fluid is used which, when pressurized, allows the deformation of said piece on a mold. Several techniques are used to pressurize the fluid.
• electro-hydroforming process One of the processes used is a so-called electro-hydroforming process. This process is based on the principle of an electric discharge in the fluid stored in a tank. The amount of electric energy released generates a pressure wave whose propagation in the fluid allows the plastic deformation of the mechanical part against the mold. To do this, electrodes positioned in the fluid are adapted to release an electrical charge stored in energy storage capacities.
• US-6,591,649 discloses an electro-hydroforming device comprising a substantially elliptical shaped vessel closed by a mold, a workpiece and a set of electrodes coupled to an electrical energy storage device adapted to generate a pressure wave.
• This pressure wave of relatively high power, strikes both the workpiece and the tank of the electro-hydroforming device.
• repeated shocks can, on the one hand, cause wear premature tank and on the other hand generate problems of weld failure on some parts of the electroforming device.
• US2010 / 0154502 discloses a method and apparatus for rapidly producing medical housings.
• the rapid formation of these housings is achieved by creating a pressure wave in a liquid contained in an enclosure.
• An impression and a part to be deformed are arranged on the path of the pressure wave in the chamber and the pressure wave comes to marry the piece to deform the contours of the impression.
• stiffeners can be installed outside the walls which increases their rigidity while controlling the thickness thereof.
• this technological solution does not offer satisfactory results.
• the object of the present invention is therefore to provide an electro-hydroforming device comprising a vessel whose reliability is improved compared to the devices of the prior art while reducing the mass thereof and maintaining a very good efficiency of forming.
• the present invention will advantageously provide an electro-hydroforming device having a controlled manufacturing cost.
• the present invention provides an electro-hydroforming device having a vessel with an inner vessel wall and within which are positioned a mold, a first electrode and a second electrode.
• a first free reflector is placed in the vessel and surrounds the mold, the first electrode and the second electrode.
• the reflector is free because it is not rigidly connected to the tank and / or to the elements integral with the tank. It is mounted in the tank so to be able to move in relation to this one. Of course, these trips must be limited and controlled.
• the tank is less stressed by pressure waves caused by the triggering of an electric arc between the first electrode and the second electrode. Indeed, the pressure waves are reflected in large part by the first reflector, which limits the bias of the inner vessel wall.
• the first reflector is for example of cylindrical shape.
• the section of this cylindrical shape then depends for example on the part to be formed.
• this first reflector will be circular cylindrical.
• the first reflector is positioned concentrically with respect to the mold, the shape of which generally corresponds to that of the part to be formed.
• the first reflector is preferably composed of a metal or a metal alloy.
• a second reflector is preferably placed substantially parallel to a cover between the first electrode and said cover.
• the second reflector has for example a disc shape for better confinement of the pressure waves when the first reflector is of circular cylindrical shape.
• the second reflector is connected to the cover for example by connecting means in the form of dampers.
• the second reflector can move in at least one degree of freedom with respect to the cover.
• a space separates the inner wall of the tank from an outer reflector wall of the first reflector and is filled with the same fluid as the tank, which allows the tank to be exposed less to the pressure waves during a forming process.
• FIG. 1 is a schematic cross-sectional schematic view of an electro-hydroforming device according to the present invention
• FIG. 2 is a partial schematic view of another embodiment of the invention.
• Figure 3 is a partial perspective view of an electro-hydroforming device according to another embodiment.
• FIG. 1 shows an electro-hydroforming device 2 comprising a frame 4, a tank 6, a mold 10, a first electrode 11, a second electrode 12 and a first reflector 14.
• the frame 4 is adapted to support and hold the tank 6 on a base 16 which may be for example metal or concrete.
• the frame 4 meanwhile can be made of a metal or a metal alloy such as hardened steel.
• the tank 6 is adapted to receive and contain a fluid 8 which is in our example water.
• a lid 30 is placed on the tank 6 and is fixed by means of suitable fastening means (not shown in the figures) to hold the lid 30 on the tank 6 during the execution of a forming process. Also, a seal 32 between an edge of the tank 6 and an edge of the lid 30 is used.
• the mold 10 is preferably centered on the vertical axis of symmetry AA 'of the tank 6. It has an indentation 24 fixed to a mold support 22 by means of screws for example.
• the mold 10 comprises an internal pipe 27 coupled to a pumping device (not visible in the figures) making it possible to obtain a desired vacuum under a workpiece 26.
• a pumping device not visible in the figures
• a fastening device 28 is positioned facing the mold 10 and allows holding in a desired position of the workpiece 26.
• the first electrode 1 1 and the second electrode 12 are positioned in the tank 6, preferably on the vertical axis of symmetry A-A '. They are adapted to generate at least one electric arc in the fluid 8.
• the first electrode 1 1 and the second electrode 12 are spaced apart by an adjustable interelectrode space (FIG. 1).
• the first electrode 11 and the second electrode 12 are held in the tank 6 by means of a rod 29 (FIG. 1) fixed to the cover 30.
• the rod 29 has an adjustable length making it possible to control a distance between the mold 10 and the second electrode 12.
• the generation of an electric arc between the first electrode 1 1 and the second electrode 12 allows the creation in the fluid 8 of pressure waves called direct pressure waves to deform the workpiece 26.
• the direct pressure waves are propagate concentrically with respect to the inter-electrode space (represented by continuous line arrows in FIG. 1).
• the first reflector 14 is positioned in the tank 6 and is preferably of cylindrical shape. It has a diameter adapted to surround the mold 10, as well as the first electrode 1 1 and the second electrode 12.
• the first reflector 14 has an inner reflector wall 34 and an outer reflector wall 36.
• the first reflector 14 is free to movements in the vessel 6 and can move in a controlled manner therein in at least one degree of freedom. In addition, it must be rigid enough to withstand pressure waves and reflect them. It is made for example of a metal or a metal alloy and it has for example a thickness of about 3cm.
• the diameter of the first reflector 14 is such that a space 38 (FIG. 1) is present between the inner vessel wall 18 and the outer reflector wall 36 of the first reflector 14.
• This space 38 in the embodiments of FIGS. and 2, contains the same fluid 8 as that contained in the tank 6.
• the inner vessel wall 18 is less stressed during a forming process, to reduce its thickness.
• shims (not shown in the figures) positioned between the inner vessel wall 18 and the outer reflector wall 36 can be used to hold the first reflector 14 in the vessel 6. They are positioned on a portion and / or an upper part of the first reflector 14 by means of holding means (not shown in the figures).
• the wedges make it possible to maintain the first reflector 14 before, during and after the forming process of the workpiece 26 in an optimal position.
• the diameter of the first reflector 14 is substantially larger than the diameter of the mold 10 containing the workpiece 26.
• the pressure waves are confined to a useful surface corresponding to the surface of the workpiece. form 26, optimizing the forming process.
• the use of such a first reflector 14 makes it possible to minimize the exposure of the bottom of the tank 20, and in particular the zone of connection between the inside wall of the tank 18 and the bottom of the tank 20, to the pressure waves during a forming process, thus improving the service life of the tank 6.
• the surface of the workpiece 26 is applied in addition to direct pressure waves pressure waves called indirect pressure waves.
• the indirect pressure waves are the result of the reflection of a portion of the direct pressure waves on the inner reflector wall 34 and on the cover 30.
• the pushing time on the workpiece 26 is increased allowing improve the forming process.
• FIG. 2 has the same geometry as that disclosed in FIG.
• an air cushion 45 filled with pressurized air is positioned in the space 38 between the inner vessel wall 18 and the outer wall of the vessel.
• Reflector 36 The air cushion 45 of synthetic material is of toric shape for example (FIG. 2) can be positioned indifferently over the entire height of the first reflector 14.
• two air cushions 45 positioned respectively on a part high of the first reflector 14 and on a lower part of the first reflector 14 can be used to reduce the impact of the pressure waves on the tank 6 while maintaining the first reflector 14 in an optimal position, as shown in Figure 2.
• a second disk-shaped reflector 15 having a diameter adapted to the diameter of the first reflector 14 is also noted.
• This second reflector 15 substantially close the top of the first reflector 14 and is also immersed in the tank 6 ( Figure 2).
• the second reflector 15 is positioned between the first electrode 1 1 and the cover 30. It is spaced from the cover 30 and is substantially parallel to the latter. It is free of movement relative to the tank 6 according to at least one degree of freedom.
• it makes it possible to increase the inertia of the first reflector 14.
• the space between the second reflector 15 and the lid 30 is filled with the fluid 8 of the tank 6 but may also possibly have a cushion of air maintained under pressure. Thus, damping or absorption of pressure waves by the device is improved.
• the second reflector 15 is preferably connected to the cover 30 by suitable connecting means 44, such as for example pneumatic or elastomeric dampers. They may be arranged in an exemplary embodiment, over the entire periphery of the lid 30.
• the space 38 between the inner vessel wall 18 and the outer reflector wall 36 is filled with air that can be pressurized.
• a circular envelope of synthetic material can store the air at a predetermined pressure and thus provide a seal between the air (contained in the circular envelope) and the water contained in the tank 6.
• the transmission of pressure waves to the tank 6 is attenuated.
• the tank 6 is less stressed to reduce the thickness of the tank 6 and thereby its mass.
• supports 42 are positioned between the vessel 6 and the frame 4. They are preferably positioned on a periphery of the The thickness of the supports 42 and the material used are adapted to distribute the force of the tank 6 on the frame 4 during the forming process.
• the present invention therefore proposes an electro-hydroforming device with at least one reflector positioned in the tank making it possible to reduce the impact of the pressure waves on the tank and thus increase its service life.
• the presence of at least one reflector in the tank makes it possible to reduce the thickness thereof and hence its mass.

Landscapes

• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Shaping Metal By Deep-Drawing, Or The Like (AREA)
• Supply Devices, Intensifiers, Converters, And Telemotors (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=53200043

Family Applications (1)

Country Status (6)

Family Cites Families (23)

• 2014
  • 2014-12-29 FR FR1463410A patent/FR3031053B1/fr not_active Expired - Fee Related
• 2015
  • 2015-12-29 CN CN201580074203.8A patent/CN107206456B/zh active Active
  • 2015-12-29 US US15/540,938 patent/US10758960B2/en active Active
  • 2015-12-29 EP EP15820177.2A patent/EP3240647B1/de active Active
  • 2015-12-29 WO PCT/EP2015/081372 patent/WO2016107881A1/fr active Application Filing
  • 2015-12-29 JP JP2017552236A patent/JP6678186B2/ja active Active

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