EP3720625A1

EP3720625A1 - Device for incremental stamping by magnetic forming and associated method

Info

Publication number: EP3720625A1
Application number: EP18814897.7A
Authority: EP
Inventors: Gilles Avrillaud
Original assignee: ADM28 SARL
Current assignee: ADM28 SARL
Priority date: 2017-12-07
Filing date: 2018-12-06
Publication date: 2020-10-14
Also published as: CN111511479A; FR3074704B1; US20210187578A1; JP2021505400A; FR3074704A1; WO2019110760A1

Abstract

The invention relates to a device for stamping a blank (50) in order to produce a stamped part. The device includes a punch (40) comprising a bearing surface (41), an anvil (70), a die (80) and means for generating a magnetic field (60), provided in the punch, level with the bearing surface. The device is configured, in an initial position, so that: - the bearing surface of the punch receives a portion of a first face of the blank, - the anvil and the means for generating a magnetic field are placed on either side of the same portion of the blank, the means for generating a magnetic field (60) being opposite the first face (51), and the anvil (70) opposite a second face (52) of the blank, at a distance from the second face, - the die (80) is placed opposite the second face (52), level with another portion of the blank. The means for generating a magnetic field are configured to apply pressure on the blank in the direction of the anvil, in a direction Z'Z. The device includes first means (43) for moving the punch in the direction Z'Z and second means (72) for moving the anvil in the same direction.

Description

INCREMENTAL MAGNETEFORMING PADDING DEVICE

AND ASSOCIATED METHOD

Field of the invention

The present invention relates to the field of forming, more particularly to stamping.

The present invention relates to a device and a process for stamping blanks by magnetic pulse for the production of stamped parts, in particular so-called deep-drawn parts.

State of the art

In the field of forming, in particular metal, stamping is a method very often chosen because robust and well controlled.

Embossing is commonly used in industry, especially in the automotive industry to form including trim panels, such as a hood or a door of a motor vehicle, because of high production rates eligible.

Embossing is a forming process consisting in obtaining by plastic deformation of a blank, under the action of a pressure, a piece of more or less complex shape.

The stamping device for implementing this method is essentially composed of a matrix and a punch of quasi-complementary shape, between which the blank is positioned. Obtaining the shape is done by driving the blank under the action of the punch in the matrix. The movement of the blank is generally controlled by a blank holder, imposing a retaining pressure, in order to reduce the appearance of wrinkles or tears on the final stamped part.

However, in the presence of a difficult to form part, including a deep drawn part, the choice of the clamping force to be printed at the blank holder is difficult. If the blanking force is too high, the folds are removed but the risk of tearing is high. If the blanking force is too weak, the risk of wrinkling is high. To make deep-drawn parts, alternatives to the stamping process are known.

Among them, there may be mentioned the hydroforming process. In this process, the blanks are shaped by the action of a fluid under pressure.

The associated hydroforming device consists of a hermetically sealed enclosure formed in two parts, a hollow mold having a cavity complementary to the shape of the part that is desired. The blank is placed inside the enclosure. Hydraulic pressure is exerted on the latter to press against the mold cavity. This quasi-static shaping process has the major advantage of dispensing with punching and making complex shapes, particularly undercut. However, high pressures are essential for forming which tends to require large presses for large parts. As a result, this method is mainly used for forming tubular pieces. One of the disadvantages of the process is the cycle time, often several tens of seconds because of the filling and pressurization times.

Among the existing hydroforming processes, there may be mentioned the electro-hydroforming process, said process EHF (Anglo-Saxon Electro Hydraulic Forming), which is, in turn, a high-speed deformation process. Such a method has many advantages, including a significant reduction in the springback and increased formability of the metals. However, the major drawbacks lie in the need to put the part to be in contact with water (possible corrosion and necessary drying) and the management of the water.

There may also be mentioned hot forming processes, such as the superplastic forming process, known as the SPF (Superplastic Forming Anglo-Saxon) process. This process is based on the ability of certain alloys, for example titanium, to withstand significant deformation. These alloys, hereafter called superplastic alloys, can reach elongations sometimes going beyond 1000% under certain conditions. temperature, pressure and deformation whereas conventional alloys generally deform only in a typical range of a few% to 50%.

The associated SPF forming device consists of a closed chamber hermetically formed in two parts, including a hollow mold having a footprint complementary to the final external geometry of the part that is desired. The blank is placed inside the enclosure and held firmly between the two parts. A gas under pressure is injected into the chamber and comes to press the blank, by deforming it, against the impression. The pressure and the temperature, of the order of 900 ° C for titanium alloys, must be perfectly controlled.

The obvious disadvantages associated with this SPF forming device and the associated method lie in the cycle time, the cost and the fact that only certain materials are usable.

Presentation of the invention

The present invention aims in particular to overcome all or part of the limitations of prior art solutions, including those described above, by providing a solution that allows to obtain stamped parts, including deep-drawn parts .

For this purpose, the invention is aimed primarily at a device for stamping a blank for the production of a stamped part comprising:

a punch having a bearing surface,

- an anvil,

- a matrix,

means for generating a magnetic field, disposed in the punch, at the level of the bearing surface.

By the term "blank" is meant a thin plate, in particular of metallic material. A plate is said to be thin when one of its dimensions is significantly smaller than the other two, typically at least an order of magnitude. In an initial position, that is to say before the stamping phase, the stamping device is configured such that:

the bearing surface of the punch is intended to receive part of a first face of the blank,

the anvil and the means for generating a magnetic field are intended to be arranged on either side of the same part of the blank.

The means for generating a magnetic field are vis-à-vis the first face. The anvil is opposite a second face of the blank, opposite the first face, at a distance from said second face. The die is intended to be disposed opposite the second face, at another portion of the blank.

The means for generating a magnetic field are designed and configured to print the blank a pressure in the direction of the anvil, in a Z'Z direction.

The stamping device comprises first displacement means arranged to move the punch relative to the die in the Z'Z direction. The punch is advantageously moved in translation.

The stamping device comprises second displacement means arranged to move the anvil, relative to the matrix, in the Z'Z direction.

The punch, the anvil and the matrix are preferably made of a metallic material to contain the high pressures generated by the means for generating a magnetic field.

The stamping device according to the invention differs from conventional stamping devices in that stamping is not performed by the punch itself, but by the means for generating a magnetic field.

Similarly, the means for generating a magnetic field are used differently from the conventional frame of a magneto-forming process which forms the entire blank at one time. The means for generating a magnetic field are arranged so as to generate pulses magnetic than on a portion of the blank. The relative displacement of the punch with respect to the generating means makes it possible to move the area of the blank that will be touched by the magnetic pulses.

Such a device thus advantageously makes it possible to work at high speed of expansion deformation, with the advantages that magnetoforming can bring, such as obtaining radii of curvature of less than 2 mm, fine engravings, or tight tolerances, as well as the avoidance of cracking or tearing of the material in areas of high elongation, especially for aluminum.

Such a stamping device is thus particularly suitable for the production of stamped parts, particularly deep-drawn parts, without generating tearing parts.

It is also adapted to the realization of fallen edges, with the advantages of the magnetoforming mentioned above.

According to preferred embodiments, the invention also satisfies the following characteristics, implemented separately or in each of their technically operating combinations.

According to preferred embodiments, the first displacement means comprise a linear actuator.

According to preferred embodiments, in order to obtain good efficiency of the method, the means for generating a magnetic field are in the form of a flat coil, for example a spiral coil. The coil is disposed substantially in a plane parallel to the bearing surface of the punch.

According to preferred embodiments, the stamping device comprises a blank holder configured to hold the other part of the blank against the die, to impose a retaining pressure on the movement of the blank, against the die in order to limit the formation of the blank. folds.

The invention also relates to a method for magnetic pulse stamping of a blank for the production of a stamped part, from a stamping device according to at least one of its embodiments. The method comprises the steps of: a) positioning the blank in the stamping device, b) subjecting the blank to a magnetic field caused by the means for generating a magnetic field so that pressure is exerted on the first face of the blank in the direction Z'Z and comes to press said blank against the anvil,

c) displacement of the punch by the first displacement means and the anvil by the second displacement means, relative to the matrix, in the direction Z'Z,

steps b) and c) being repeated, preferably in a synchronized manner, until the desired shape is obtained for the finished stamped part.

By synchronized means that the steps are performed either successively, one after the other, or simultaneously.

As the punch moves, a magnetic pulse is generated by the means for generating a magnetic field, exerting, on the one hand, an axial pressure on the blank in the direction of the anvil, coming to press said blank on said anvil, and on the other hand, a radial pressure on the blank in the direction of the die, coming to press said blank on said die.

This double pressure, axial and radial, advantageously allows to deform the blank, without the risk of generating tear to the piece that is desired and with excellent precision shaping.

Presentation of figures

The invention will be better understood on reading the following description, given by way of non-limiting example, and with reference to the figures which represent:

1 to 4 are diagrammatic sectional views of an embodiment of a stamping device according to the invention showing the successive steps of stamping a blank,

Figure 5, a schematic view equivalent to Figure 1 illustrating a particular embodiment of the stamping device with a blank holder. In these figures, identical references from one figure to another designate identical or similar elements. For the sake of clarity, the elements shown are not to scale, unless otherwise stated.

Detailed description of an embodiment of the invention

A stamping device 10, as illustrated in FIGS. 1 to 4, is intended for stamping blanks 50 in order to produce stamped parts, in particular deep-drawn parts.

In an exemplary embodiment, the blanks 50 are made of a metallic material, such as steel.

The blank 50 has a first face 51 and a second face 52, opposite to the first.

In a preferred embodiment, not limiting of the invention, the stamping device 10, as shown in section in FIGS. 1 to 4, is suitable for producing cups. By bucket is meant a stamped part having a hollow cylindrical shape, with or without flange flange.

Man will readily understand that the teaching of the present invention is transposable to other embodiments.

In the present description, terms such as upper, lower, upper, lower, left, right are used for the sake of simplicity, with reference to the orientation of the various elements shown in Figures 1 to 4. However, unless otherwise indicated these terms only characterize the relative arrangement of these elements, after an imaginary possible rotation with respect to the effective orientation of the set in space.

The stamping device 10 comprises a first frame 20 and a second frame 30. The first frame 20 may represent a lower part of the drawing device and the second frame 30, an upper part, as illustrated in the figures. Alternatively, and without departing from the scope of the invention, the first frame 20 may represent an upper left or right part of the stamping device and the second frame 30, respectively a lower part, right or left. First build

The first frame 20 is in the form of a first hollow body defining a first open cavity 23, preferably central.

In a particular embodiment, the first open cavity 23 has a cylindrical shape, preferably of circular cross section.

As illustrated in FIGS. 1 to 4, the first hollow body is formed of a lower part 21 and of a lateral part 22 whose internal wall 221 delimits the first open cavity 23.

A punch 40 is disposed in the first open cavity 23.

In the particular example where the final desired pressed piece is a bucket, the punch 40 is in the form of a cylindrical body, preferably of circular cross section, and longitudinal axis Z'Z.

In the example of FIGS. 1 to 4, the longitudinal axis of the punch 40 is a vertical axis, preferably coinciding with a longitudinal axis of the first open cavity 23.

The punch 40 is preferably solid and made of material capable of containing the high pressures generated by the means for generating a magnetic field, for example a metallic material.

The punch has a bearing surface 41 and a lateral surface

42. The bearing surface 41 is intended to receive a portion of the blank to be stamped. The lateral surface 42 is intended to face the inner wall 221 of the lateral portion 22 of the first hollow body, when the said punch is positioned in the first open cavity 23.

The punch 40 is movable in the first open cavity 23. The punch 40 is movable in translation along its longitudinal axis Z'Z between:

a retracted position, in which said punch is located in the first open cavity 23, and

an extended position, in which said punch is located outside the first open cavity 23. The punch 40 moves in a Z'Z direction towards its deployed position. The punch 40 moves in a direction ZZ 'towards its retracted position.

In the example of Figure 4, the punch 40 is shown in the deployed position.

First moving means 43 are configured to move the punch 40 between the retracted position and the extended position. The first moving means 43 are actuated manually or automatically.

In an exemplary embodiment, the first displacement means 43 comprise at least one linear, hydraulic or pneumatic actuator, such as a jack operating between the first frame 20 and the punch 40. In this embodiment, preferably, the fixed part of the linear actuator - for example the body of the jack - is housed in the first open cavity 23 formed in the first frame 20. The movable part of the linear actuator, for example the piston of the jack, is able to move out of the first open cavity 23 to deploy the punch 40 in the direction Z'Z and able to move towards the first open cavity 23 in the direction ZZ 'to return the punch 40 in its retracted position. Particularly advantageously, control means control the first displacement means 43 of the punch.

In an alternative embodiment, the first displacement means 43 are in the form of a support carrying a thrust screw capable of cooperating with the punch 40 to move it in translation along the longitudinal axis Z'Z.

The drawing device 10 further comprises means for generating a magnetic field 60.

The means for generating a magnetic field 60 are arranged, at the bearing surface 41 of the punch 40, inside said punch.

The means for generating a magnetic field 60 are configured to create a concentrated magnetic field in a delimited space and over a very short period, as will be described later. In a preferred embodiment, the means for generating a magnetic field 60 are in the form of a flat coil, for example spiral. The flat coil is preferably arranged in a plane substantially parallel to the bearing surface 41 of the punch 40.

The means for generating a magnetic field 60 are preferably part of an assembly which further comprises an electrical energy storage unit and one or more switches (not shown).

The electrical energy storage unit is configured for and intended to store a moderate energy, for example of the order of a few kilojoules to a few tens of kilojoules (kJ).

In a preferred embodiment, the storage unit is a discharge capacitor bank.

Second frame

The second frame 30 is in the form of a second hollow body delimiting a second open cavity 33.

In a particular embodiment, the second open cavity 33 has a cylindrical shape, preferably of circular cross section.

As illustrated in FIGS. 1 to 4, the second hollow body is formed of an upper portion 31 and of a lateral portion 32 whose inner wall 321 delimits the second open cavity 33.

The second frame 30 is arranged relative to the first frame 20 so that the second open cavity 33 is intended to receive the punch 40, when the latter moves along its longitudinal axis Z'Z, in the direction Z'Z, to its deployed position. A free end 322 of the lateral portion 32 of the hollow body of the second frame 30 is substantially vis-à-vis a free end 222 of the lateral portion 22 of the first hollow body of the first frame 20.

The second hollow body and the punch 40 have dimensions such that the punch 40 can move, in translation, freely in the second open cavity 33 and allow the passage of the blank 50, in its thickness, between the inner wall 321 of the second open cavity 33 and the lateral surface 42 of the punch 40.

In a preferred embodiment, the side surface 42 of the punch 40 and the side wall 32 of the second hollow cavity 33 are of substantially complementary shape, the thickness of the final stamped piece and a set of operation.

In a nonlimiting embodiment, when the punch 40 is in the form of a cylindrical body, of circular cross section, the second open cavity 33 is cylindrical, of circular cross section, with a diameter greater than the outside diameter of the punch. .

In the example of FIGS. 1 to 4, and preferably, a longitudinal axis of the second open cavity 33 coincides with the longitudinal axis of the punch 40.

The stamping device further comprises an anvil 70.

The anvil 70 is housed in the second open cavity 33. Said anvil is movable in the second open cavity 33. The anvil is movable in translation along the longitudinal axis Z'Z, second displacement means 72 are configured to move the anvil 70 in translation in the second open cavity 33.

The second moving means 72 are actuated manually or automatically.

In an exemplary embodiment, the second displacement means 72 comprise at least one linear, hydraulic or pneumatic actuator, such as a jack operating between the second frame 20 and the anvil 70. In this embodiment, preferably, the part fixed linear actuator - for example the body of the jack - is housed in the second open cavity 33. The moving part of the linear actuator, for example the piston of the jack, is able to move in the second open cavity 33 for moving the anvil 70 into said second cavity. So particularly advantageous, control means control the second displacement means 72 of the anvil 70.

In an alternative embodiment, the second displacement means 72 are in the form of a support carrying a thrust screw capable of cooperating with the anvil 70 to move it in translation along the axis ZZ '.

In a preferred embodiment, the first 43 and second 72 moving means are similar.

The stamping device further comprises a matrix 80.

The matrix 80 is disposed at the free end 322 of the lateral portion 32 of the second frame 30. The free end 322 of the lateral portion 32 of the second frame 30 forms a lower surface 81 of the matrix 80.

In a preferred embodiment, the lateral portion 32 of the second hollow body of the second frame 30 forms the die 80.

The anvil 70 and the matrix 80 are preferably made of a metallic material, for example steel, having a sufficient structural strength to contain the high pressures generated by the impact of the blank 50 on said anvil and said matrix, when of the stamping process which will be described later.

The punch 40, the anvil 70, the matrix 80 and the means for generating a magnetic field 60 are arranged relative to each other so that, in an initial position of the stamping device 10 (FIG. 1) , that is to say before the start of the stamping process, the blank 50 is positioned flat between said various elements.

More specifically, the punch 40 is positioned so that its bearing surface 41, in a retracted or intermediate position of said punch, is intended to receive a portion of the first face 51 of the blank 50. In the example illustrated by FIG. 1, the bearing surface 41 of the blank is intended to receive a central portion of the first face 51 of the blank 50. The anvil 70 and the means for generating a magnetic field 60 are arranged on either side of the blank. the same part of the blank 50. The means for generating a field 60 are facing the first face 51 of the blank 50. A lower surface 71 of the anvil 70 is vis-à-vis the second face 52 of the blank 50.

The lower surface 71 of the anvil 70 is disposed opposite the second face 52 of the blank 50, at another portion of the blank. In the example illustrated in Figure 1, the lower surface 81 of the die 80 is disposed opposite the second face 52 of the blank 50, at a peripheral portion of said blank.

The lower surface 71 of the anvil 70 is disposed at a distance from the second face 52 of the blank 50.

Preferably, as illustrated in FIG. 1, the means for generating a magnetic field 60, as positioned, are thus able and intended to print on the blank 50 a pressure mainly in the direction of the lower surface 71 of the anvil 70, according to the direction Z'Z.

In one embodiment, illustrated in FIG. 5, the stamping device 10 comprises a blank holder 90. The blank holder 90 is housed between the free ends 222, 322 of the lateral portions 22, 32 of the first and second bodies hollow. It is configured so that the blank is compressed between the blank clamp and the die, at the free end 322 of the lateral portion 32 of the second hollow body, when said blank is in position on the punch 40. the blank greenhouse force and / or the clearance between the blank and the matrix will condition the swallowing of the blank during its shaping by preventing or limiting the formation of folds.

In an exemplary embodiment, the blank holder 90 is held pressed against the free end 322 of the lateral portion 32 of the second frame 30 by compression means such as for example gas springs.

An example of a stamping process is now described.

The blank 50 is intended to conform to the shape of the lower surface 71 of the anvil 70 and the inner wall 321 of the side portion 32 of the second frame 30 to form a deep bucket-type deep draw. The bucket obtained may or may not have a flange flange. In a prior step, the blank 50 is cut to the desired dimensions (length and width, or diameter, and thickness) in a sheet.

In a first step, called step a), the blank 50 is positioned in the drawing device 10.

The blank 50, of substantially flat shape, is positioned between the first frame 20 and the second frame 30, as illustrated in FIG.

In one embodiment, the blank 50 is disposed on the one hand, at its central portion, on the punch 40. The blank 50 is arranged so that its first face 51 bears against the surface of the blank. support 41 of the punch.

The blank 50 is arranged so that its second face 52 is opposite the lower surface 71 of the anvil 70. The lower surface 71 of the anvil 70 is positioned at a distance e from the second face 52 of the blank 50.

The distance e defines the desired depth for the deformation of the blank at each discharge (described below). The distance e is maximized so as to reduce the number of discharges and consequently the forming time.

The blank 50 is disposed on the other hand, at its peripheral portion, between the lower surface 81 of the matrix 80, therefore the free end 322 of the lateral portion 32 of the second pack 30i, and the free end 222 of the side portion 22 of the first frame 20. The second face 52 of the blank 50 is disposed opposite the die 80, at a distance therefrom. The first face 51 of the blank 50 is disposed facing the free end 222 of the lateral portion 22 of the first frame 20.

In an exemplary implementation, when the blank 50 has been deposited on the punch 40, said punch is moved, from its retracted position, in translation in the direction Z'Z, to shift the blank 50 so that the second side 52 of said blank, at the peripheral portion of the blank, is placed in the immediate vicinity, for example of the order of a millimeter, the free end 322 of the side portion 32 of the second frame 30, so the surface lower 81 of the matrix 80. When the stamping device 10 comprises a blank holder 90, the blank 50 is held in abutment against the free end 322 of the side portion 32 of the second frame 30 by said blank holder.

The method then comprises a second step, called step b), of deformation of the blank 50 by magneto-forming.

The central portion of the blank 50, located near the means for generating a magnetic field 60, is subjected to a magnetic field coming from said means for generating a magnetic field 60 so that an axial pressure is exerted against the first face 51 of the blank 50, and tightly press said blank against the lower surface 71 of the anvil 70. The arrow illustrated in Figure 2 shows the direction of the axial pressure exerted on the blank 50.

The blank 50 is deformed accordingly to come to bear against the lower surface 71 of the anvil 70.

During this step b) shown in FIG. 2, the means for generating a magnetic field 60 progressively deforms the central portion of the blank 50 so as to obtain a first depth stamp P1, less than a depth P of the stamping final sought. The peripheral portion is pressed against the free end 322 of the lateral portion 32 of the second frame 30, thus against the lower surface 81 of the die 80.

The anvil 70 advantageously makes it possible to limit the impact of the discharge on the blank and to avoid a tear in it.

At the end of this step b), the blank 50 is deformed and has a first stamp.

In a third step, said step c), the punch 40 and the anvil 70 are moved.

The punch 40 is moved by the first moving means 43, in the direction Z'Z, until the bearing surface 41 of the punch is pressed again against the first face 51 of the blank 50, so that the central portion of the blank 50 returns in the immediate vicinity of the means for generating a magnetic field 60. The peripheral portion of the blank 50 is kept at a distance from the die 80, as illustrated in FIG. The displacement of the punch 40 is made in the same direction as the direction of displacement of the central portion of the blank 50 during step b).

The anvil 70 is moved by the second moving means 72, in the Z'Z direction.

In an exemplary implementation, the relative displacement of the punch 40 and the anvil 70 relative to the matrix 80 is performed incrementally, preferably simultaneously.

The displacement of the punch 40 and that of the anvil 70 is not necessarily the same amount.

The anvil 70 is moved in the Z'Z direction by a sufficient distance so as to define the desired depth for the incremental deformation of the blank.

In an exemplary implementation, the relative movement of the punch 40 and the anvil 70 is made continuously. The shaping of the blank 50 by the means for generating a magnetic field 60 can be regarded as instantaneous with respect to the displacement of the punch 40 and that of the anvil 70. Indeed, the duration of the displacement of the punch 40, and that of the displacement of the anvil 70, is generally very slow (of the order of one second) with respect to the duration of the magnetic pulse generated by the means for generating a magnetic field 60 (of the order a few micro seconds). In the particular case of this embodiment, the second and third steps are performed simultaneously without modifying the result of said steps.

In a fourth step, steps b) and c) are reproduced sequentially.

Steps b) and c) are reproduced until the depth P of the final stamped part desired is obtained.

As the relative displacement of the punch 40 and the anvil 70 relative to the matrix 80 increases, said means for generating a magnetic field 60 advantageously exert an axial pressure on the central portion of the blank 50 in the direction of the anvil 70, coming off the board central of said blank on said anvil. Said means for generating a magnetic field 60 also exert a radial pressure on the blank 50 in the direction of the die 80, against the inner wall 321 of the lateral portion 32 of the second frame 30, coming to press said blank against said inner wall. The horizontal arrows illustrated in FIGS. 3 and 4 represent the direction of the radial pressure exerted on the blank 50. This radial pressure of the blank 50 against the inner wall 321 of the lateral portion 32 of the second frame 30 advantageously allows said blank to come perfectly fit the shape of said inner wall.

The number of iterations of steps b) and c) depends in particular on the material constituting the blank, the desired depth of the stamped part.

At the end of the stamping process, the blank became a deep-drawn piece, of the bucket type, with or without flange flange.

In the example of FIG. 4, the bucket is of the bucket type with no flange flange.

The present invention is not limited to the preferred embodiments described above by way of non-limiting examples and the variants mentioned. It also relates to the embodiments within the scope of the skilled person.

The above description clearly illustrates that by its different characteristics and advantages, the present invention achieves the objectives it has set for itself. In particular, it proposes a stamping device adapted to the production of stamped parts, particularly deep-drawn parts, without generating folds or tearing parts. Such a stamping device and the associated stamping process makes it possible to work the part at high speeds, and advantageously to deform the blank without the risk of generating tears to the part that it is desired to obtain and with an excellent accuracy of setting in shape.

The invention also advantageously makes it possible to produce dropped edges.

Claims

1. Device for stamping (10) a blank (50) for producing a stamped part comprising:

a punch (40) comprising a bearing surface (41),

an anvil (70),

a matrix (80),

means for generating a magnetic field (60) arranged in the punch (40) at the bearing surface (41), said stamping device being configured, in an initial position, so that than :

the bearing surface (41) of the punch (40) is intended to receive part of a first face (51) of the blank (50),

the anvil (70) and the means for generating a magnetic field (60) are intended to be arranged on either side of the same part of the blank (50),

the means for generating a magnetic field (60) facing the first face (51), and the anvil (70) facing a second face (52) of the blank (50), opposite to the first face (51), away from said second face,

the matrix (80) is intended to be disposed opposite the second face (52), at another portion of the blank (50), said means for generating a magnetic field (60) being intended for and configured to print to the blank (50) a pressure towards the anvil (70) in a Z'Z direction,

the stamping device comprising first moving means (43) arranged to move the punch (40) relative to the die (80) in the direction Z'Z,

and second moving means (72) arranged to move the anvil (70) relative to the die (80) in the Z'Z direction.

2. Stamping device (10) according to claim 1 wherein the first moving means (43) comprise a linear actuator.

3. Stamping device (10) according to one of the preceding claims wherein the means for generating a magnetic field (60) are in the form of a flat coil.

4. Stamping device (10) according to one of the preceding claims comprising a blank holder (90) configured to hold the other portion of the blank (50) against the matrix.

5. A process for magnetic pulse depressing a blank (50) for producing a stamped part, from a stamping device (10) according to one of claims 1 to 4, comprising the steps of:

a) positioning the blank (50) in the stamping device

(10)

b) subjecting the blank (50) to a magnetic field caused by the means for generating a magnetic field (60) so that pressure is exerted on the first face (52) of the blank (50) in the direction Z'Z and comes to press said blank against the anvil (70),

c) displacement of the punch (40) by the first displacement means (43) and the anvil (70) by the second displacement means (72) relative to the matrix (80), in the direction Z'Z,

steps b) and c) being repeated until the desired shape is obtained for the finished stamped part.