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
  • B21D5/00—Bending sheet metal along straight lines, e.g. to form simple curves
  • B21D5/02—Bending sheet metal along straight lines, e.g. to form simple curves on press brakes without making use of clamping means
  • B21D5/0209—Tools therefor

Definitions

• the invention relates to a method for bending flat metal workpieces, in particular sheet steel, by bending freely, also referred to as free-bending or air-bending, over edges along a bending line with a straight linear movement of the tool.
• the shaping is performed according to the invention by
• the invention also relates to a device for performing the method according to the above paragraph, consisting of a forming die with two parallel die assemblies for holding the bending edges and a punch arranged above the forming die, wherein the die assemblies can be interchanged for setting different die widths and underneath the punch a tool carriage is arranged which can be moved in the direction of the bending line and comprises a nip roller which is aligned and adjustable against the workpiece to be bent.
• the present invention relates to bending methods standardised by DIN 8586 and in particular to the free bending of flat metal workpieces.
• bending methods such as for example according to EP 0 341 211 A2
• metal sheets are bent by means of a bending device, which comprises a punch as well as a forming die with an adjustable base.
• the punch penetrates according to the desired bending angle up to a previously defined penetration depth while simultaneously pushing the die base along the bending line.
• a simple method has been sought in which the bending angle can be adjusted precisely and which with high precision makes it possible to obtain reproducible values for the geometry of the bent workpiece.
• the bending angle should be variable locally in relation to the width of the metal sheet and thus also the springing back behaviour should be adjustable locally.
• a bending device suitable for the new method should be structured to be simpler and should be able to be used more flexibly.
• the device according to the invention therefore provides a pressure roller, in particular a steel roller with a preferably V-shaped groove, annular groove or with an elastomer coating underneath the punch.
• a pressure roller in particular a steel roller with a preferably V-shaped groove, annular groove or with an elastomer coating underneath the punch.
• DE 196 08 985 A1 shows a pulling method with a divided pressure cushion in which the hold-down plate can be driven in the manner of a counter-pulling process during the shaping.
• specific steps for compensating the springing back during sheet bending cannot be derived therefrom.
• the initial basis of the invention is the already mentioned free bending, in which according to FIG. 1 a punch is pushed from above onto a metal sheet.
• the metal sheet lies horizontally on a forming die, which is provided with two parallel die assemblies for the bending edges. If the punch is pushed with its punch tip into the forming die the metal sheet is bent downwards into the forming die, being supported laterally on the radii of the forming die edges.
• ⁇ 1 On the inner side of the metal sheet in the region of the shaping zone compressive stresses are created, whilst on the outside of the metal sheet in the region of the shaping zone there are tensile stresses.
• the metal sheet now has in the loaded state a bending angle ⁇ 1 . It consists of the lateral bending sides, which run towards the lower punch bending edge.
• the nip roller can also have different forms, such as for example that of a combination of an annular and V-groove or can have a spherical surface such as for example with a barrel. It is also possible to provide the nip roller with an elastomer coating.
• a bending angle sensor is inserted between the bending edges. Then the advance of the nip roller can be pressure controlled depending on the measurement of the sensor signal but also on the compressive force to be set. However, it is also possible to move the sensor from the outside up to the bending edges, if this is expedient in consideration of the local conditions.
• the geometry of the V-groove is such that the shaping zone is reached in the bending sides. In this case it is important that there is contact between the surface in the region of the groove and the bending part even outside the radius area.
• the groove width should preferably be greater than 2 ⁇ the bending radius or curve shape of the punch, so that with a V-shape the contact surface is as large as possible with the pressure roller along the bending line.
• the method according to the invention can be performed with a variable application of pressure. This is a great advantage mainly in the case of metal sheets with different material properties or thicknesses.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Bending Of Plates, Rods, And Pipes (AREA)

Applications Claiming Priority (3)

Publications (1)

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Family Applications (1)

Country Status (5)

Families Citing this family (5)

Citations (3)

Family Cites Families (2)

• 2006
  • 2006-03-24 DE DE102006014093A patent/DE102006014093A1/de not_active Withdrawn
• 2007
  • 2007-03-23 US US12/294,350 patent/US20110036136A1/en not_active Abandoned
  • 2007-03-23 WO PCT/AT2007/000142 patent/WO2007109819A1/de active Application Filing
  • 2007-03-23 AT AT07710531T patent/ATE453464T1/de active
  • 2007-03-23 DE DE502007002488T patent/DE502007002488D1/de active Active
  • 2007-03-23 EP EP07710531A patent/EP2001615B1/de not_active Not-in-force

Patent Citations (3)

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