EP2595770A1

EP2595770A1 - Forming tool and method for hot forming and partially press hardening a workpiece made of sheet steel

Info

Publication number: EP2595770A1
Application number: EP11729634.3A
Authority: EP
Inventors: Siegfried Lösch
Original assignee: GMF Umformtechnik GmbH
Current assignee: Gestamp Umformtechnik GmbH
Priority date: 2010-07-19
Filing date: 2011-07-06
Publication date: 2013-05-29
Anticipated expiration: 2031-07-06
Also published as: US9687898B2; WO2012010418A1; CN103003003B; DE102010027554A1; US20170252791A1; CN103003003A; KR101530367B1; WO2012010418A9; US10166589B2; US20130205863A1; KR20130054994A; PL2595770T3; ES2495997T3; EP2595770B1

Abstract

The invention relates to a forming tool and to a method for hot forming and partially press hardening a workpiece made of sheet steel, wherein the workpiece is heated prior to forming and is subsequently hot formed in a forming tool comprising a die (3) and a punch (5), wherein the forming tool comprises a cooling device (8). The method is characterized in that, in the closed state of the forming tool (1, 1'), the contact between the workpiece (2) and the contact surfaces of the die (3) and the punch (5) of the forming tool is interrupted in regions by moving apart a movable die section (3.2) and a movable punch section (5.2) from a closed position to an opened position. The die (3) is made of a first die part (3.1) and at least one second die part (3.2) movable relative to the first die part, while the punch (5) is made of a first punch part (5.1) and at least one second punch part (5.2) movable relative to the first punch part, wherein the at least one movable second die part (3.2) and the at least one movable second punch part (5.2) interact with an opening device (17, 18) causing the at least one second die part (3.2) and the at least one second punch part (5.2) to contact the workpiece for a shorter closing time than the first die part (3.1) and the first punch part (5.1).

Description

Forming tool and method for hot forming and partial press hardening of a steel sheet workpiece

The invention relates to a Ümformwerkzeug for hot forming and partial press hardening of a workpiece made of sheet steel, with a die, an insertable for forming the workpiece in a recess of the die and a punch

Cooling device. In particular, the invention relates to a method for hot forming and partial press hardening of a workpiece made of sheet steel, in which the workpiece is heated prior to forming and then hot formed in a mold and a die insertable into a recess of the die Ümformwerkzeug, wherein the Ümformwerkzeug a Cooling device has.

The hot forming of blanks made of high-strength and ultra-high-strength steels for the production of press-hardened components has been established in vehicle construction in recent years. Among other things, numerous concepts for the production of partially hardened components with different structures have been developed. A concept known from DE 10 2006 019 395 A1 is the heating of a suitable steel

existing board to a temperature above the

Austenitizing and the immediately subsequent forming in a hot forming tool, which is equipped in at least one area with a heater for local adjustment of a softer microstructure. However, this known concept has the disadvantage that at least one

Heating device must be provided, the significant

Operating costs caused. In addition, the permanent affects Heat application of the corresponding effective area of

Forming tool negative on its life (lifetime) off. The present invention is based on the object

Specify method or forming tool for hot forming and partial press hardening of sheet steel, which allows in a simple manufacturing technology, with the metal component to be produced adjacent zones with

different structures and thus different

To produce material properties.

According to the invention this object is achieved by the forming tool with the features of claim 1 and by the method with the features of claim 9.

The inventive method in which the workpiece is heated before forming and then hot formed in a forming tool, wherein the forming tool a

Cooling device is essentially by

characterized in that in the closed state of the

Umformwerkzeuges the contact between the workpiece and the

Contact surfaces of the die and the punch through

Moving apart a movable die part and a movable die part from a closed position to an open position is partially interrupted.

Accordingly, the forming tool according to the invention comprises a die, one in a recess of the die

insertable punch and a cooling device.

According to the invention, the die is made of a first die part and at least one relative to the first die part movable second mold part formed while the punch of a first stamp member and at least one movable relative to the first stamp member second stamp member is formed, wherein the at least one movable second female part and the at least one movable second

Stamping part cooperate with an opening device, which causes the at least one second female part and the at least one second stamp member contact the workpiece with a shorter closing time than the first female part and the first stamp part.

The method according to the invention and the forming tool according to the invention thus make it possible, in a simple manufacturing technique, to produce adjacent zones with different structures and correspondingly different material characteristics, such as strength and elongation, on the metal component to be produced.

An advantageous embodiment of the invention

Umformwerkzeuges is that the mold parts are movably connected to a Matrizenträger and the punch parts movable with a punch carrier, wherein the Matrizenträger and the punch carrier are each provided with a plunger, and wherein the plunger in the closed state of the first female part and the first stamp member by a further approach of die carrier and punch carrier moving apart of the at least one second

Matrices and the at least one second stamp member cause. This configuration can be compared to conventional forming tools for hot forming and

partial press hardening of steel blanks without significant additional energy consumption. Especially this embodiment does not require expensive

additional drive means for the moving apart of the tool parts, which serve to generate at least one zone with a relatively soft structure in the component. Rather, the already existing press ram can be used for this purpose, the closing of the forming tool, i. to move the stamp. When the plunger of the die carrier and the punch carrier are moved back, the at least one second die part and the at least one second die part close again before opening the die and punch, whereby the area of the workpiece (component) in which the

Contact between workpiece and tool acting surface

was interrupted, looked up. Another advantageous embodiment of the forming tool according to the invention is characterized in that the first mold part rigid and the at least one second

Matrizenenteil are movably connected to a Matrizenträger, while the first stamp member rigid and the at least one second stamp member are movably connected to a punch carrier, wherein the Matrizenträger and the

Stamp carrier are each provided with a forward and backward movement causing drive means, and wherein in the closed state of the first female part and the first stamp part, the drive means a

Move apart of the at least one second female part and the at least one second stamp member cause. This variant of the forming tool according to the invention can be operated so that, as desired, with and without

Looking up the workpiece, ie with and without re-closing of the Matrizenträger movably connected to the female part and the movable with the punch carrier - - Connected stamp part, can be manufactured. Of the

Time in which the Matrizenträger movably connected to the female part and the die carrier

movably connected stamp part can be moved apart, can be controlled variably and in dependence on the to be set in the contact area of these tool parts in the workpiece elongation. The drive means for moving apart the at least one second die part and the at least one second die part are preferably made

hydraulic, pneumatic or hydropneumatic

Working cylinders formed.

Another preferred embodiment of the forming tool according to the invention provides that the at least one second die part and / or the at least one second die part, which are moved apart in the closed state of the forming tool, have a controllable tempering device, preferably a heater. This not only ensures with high reliability that at the

Workpiece targeted one or more non-hardened areas are generated; This embodiment also creates the possibility of variably setting its material properties, such as strength and elongation, in a specific region of the workpiece, depending on the requirements imposed on the component to be produced.

In an advantageous manner, the at least one second die part and / or the at least one second die part can be made of a material or have a surface coating which conducts heat poorly in order to specifically prevent the removal of heat in the areas of the workpiece which are not hardened to counteract. For example - - Ceramics could be used as a material with low thermal conductivity.

An advantageous embodiment of the invention

Method is characterized in that the contact between the workpiece and the contact surfaces of the die and the punch of the forming tool partially by repeated or multiple moving apart of the movable die part and the movable die part of the

Closed position in the open position and then moving back the movable mold part and the

movable stamp member is interrupted clocked from the open position to the closed position. The cooling rate of the hot-formed workpiece can be arbitrarily reduced or varied in this way in a wide range. For example, if a continuous, i. interrupted contact between cooled forming tool and

Workpiece or component, the cooling rate of the component is 100 ° C / s, so at a clocked contact time of 0.2 seconds per second (ie, 0.8 seconds per second there is no contact), the average cooling rate of the component to about 20 ° C. / s be reduced.

Preferably, the clocked contact break is adjusted so that the sum of the contact times is less than the sum of the break contact times. Alternatively, the clocked contact interruption can also be set so that the sum of the contact times is equal to the sum or greater than the sum of the contact interruption times. - -

Further preferred and advantageous embodiments of the device according to the invention and of the method according to the invention are specified in the subclaims.

Hereinafter, the invention will be described with reference to a plurality

Exemplary embodiments illustrative drawing explained in more detail. Each show schematically:

Fig. 1 is a sectional view of a forming tool in

completely closed state;

FIG. 2 shows a sectional view of the forming tool of FIG. 1 in the partially closed state; FIG.

Fig. 3 shows a further forming tool completely

closed state, in a sectional view;

Fig. 4, the forming tool of Fig. 3 in partial

closed state, in a sectional view;

5 shows a hydropneumatic device for driving and controlling the partial opening of the forming tool of FIGS. 3 and 4; and

Fig. 6 is a path-time diagram showing a clocked

Illustrated interruption of the contact of forming tool and workpiece or molded component.

In the drawing, various embodiments of a forming tool according to the invention 1, \ 'for hot forming and partial press hardening of a board from higher or

Highest strength steel shown. In the case of the board Component 2 to be produced is, for example, a bumper, a B pillar or another crash-relevant body component of a motor vehicle. The

Board (workpiece) consists for example of a manganese-boron steel, in particular a manganese-boron steel from

Alloy type 22MnB5.

Portions of the component (workpiece) 2 to be hardened must be rapidly cooled from the austenitizing temperature, while portions of the component 2 that are not to be hardened may not undergo rapid cooling.

The forming tools 1, 1 'shown in the drawing offer the possibility of partially interrupting the contact between the component and the tool acting surfaces.

The forming tool 1, 1 'is designed in the manner of a deep-drawing device and has a die 3. In the die 3, a recess (recess) 4 is formed, which images the outer shape of the produced, three-dimensionally shaped component 2.

In addition, the forming tool 1, 1 'comprises a punch 5, which determines the inner shape of the component 2 to be produced. The punch 5 can by means of a not shown

Setting device (press ram) are moved from a remote from the die 3 starting position in a closed position in which it is fully retracted into the recess 4 of the die 3. The adjusting device comprises a control device which controls the speed with which the _ _

Stamp 5 enters the recess 4 of the die 3, controls.

The die 3 is subdivided into at least two die parts 3.1, 3.2, which are movable relative to each other on a

fixed support, e.g. a plate 6 of a press table are held. Accordingly, the stamp 5 is subdivided into a corresponding number of stamp parts 5.1, 5.2, wherein a respective mold part 3.1, 3.2 a so

cooperating stamp part 5.1 or 5.2 is assigned. The stamp parts 5.1, 5.2 are also held relative to each other movable on a punch carrier 7, which is formed for example from a plate. The punch carrier or the plate 7 is mounted on the adjusting device, not shown here, by means of which the punch 5 can be retracted from a starting position remote from the die 3 into the recess 4 of the die 3.

In FIGS. 1 to 4, the component 2 is to be partially hardened in each case with the tool parts 3.1, 5.1 shown on the left side, whereas the tool parts 3.2, 5.2 shown on the right side undergo hardening of the component 2

Interruption of the contact of component 2 and the

To prevent tool active surfaces 3.21, 5.21.

The active surface of the punch side 5.1 shown on the left side and / or the active surface of the associated female part 3.1 are cooled, while the active surfaces 3.21, 5.21 of

On the right side shown tool parts 3.2, 5.2, where another or relatively soft structure to be adjusted, cooled and / or preferably heated and / or from a poorly heat-conducting material or a bad - - be performed thermally conductive surface coating. For this purpose, cooling channels 8 are introduced into the stamp part 5.1 and the die part 3.1 near the active surfaces. The

Cooling channels 8 are part of a cooling device, not shown further. Depending on the required

Cooling degree, the cooling channels of water, ice water, a frozen salt solution, liquid nitrogen or other cooling medium flows through, which is suitable for the rapid removal of large amounts of heat.

Likewise, in the second stamp part 5.2 and the female part 3.2 near their active surfaces 3.21, 5.21 fluid channels 9 a tempering introduced, which is also not shown here in detail. Through the channels 9 of the tempering a cooling medium, for example, a cooling oil is passed, which causes a moderate cooling of the tool parts 3.2, 5.2 in this area. Alternatively, at least through a part of the channels 9, in particular through the channels 9.1 arranged adjacent to the first or left-hand tool parts 3.2, 5.2, a heating fluid, e.g. Hot steam to be passed. Instead of fluid channels 9 and 9.1, heating cartridges, heating spirals or heating wires can also be integrated in the tool parts 3.2, 5.2, at which a different or relatively soft structure is to be set.

To produce the component 2, a board made of high-strength or very high-strength steel (for example made of 22MnB5) is first heated to austenitizing temperature in an oven, not shown here. Subsequently, the workpiece (board) is placed in the opened forming tool 1, 1 ', so that it lies with its edge on the upper side of the die 3. Then be - -

Hold-down 10 attached, which hold down the workpiece in its edge region during the subsequent forming. The hold-down force exerted by the hold-down device 10 can be adjusted as a function of the respective deformation rate in order to optimize the flow of the

Workpiece 2 in the recess 4 of the die 3 to

enable .

Then the punch 5 is placed on the steel sheet at high speed, so that the highly cooled

End face of the stamping part 5.1, at which a press hardening of the steel sheet 2 is to take place, quickly comes into intensive contact with the associated surface portion of the steel sheet 2.

Den the right side in the figures 1 to 4

Tool parts 3.2, 5.2 is an opening device

associated, which causes the second punch part 5.2 and second die part 3.2, the workpiece 2 with shorter

Contact closing time as the first stamp part 5.1 and the first mold part 3.1. The steel sheet 2 is quenched in this way in its section 2.1 so fast that there forms a microstructure or area with a hardness that is higher than the hardness of the adjacent to the section 2.1 section 2.2 of the steel sheet.

In the exemplary embodiment illustrated in FIGS. 1 and 2, the die parts 3.1, 3.2 and the stamp parts 5.1, 5.2 are spring-supported against the associated plate 6 of the press table or the stamp plate 7. For this purpose, between the respective plate 6 or 7 and the die parts held thereon 3.1, 3.2 or stamp parts 5.1, _ -

5.2 spring elements 11, e.g. Coiled springs or the like arranged. Further, the plates 6 and 7 are provided with brackets 12 which form the matrices 3.1, 3.2 and stamp parts 5.1, 5.2 associated stops 13. By the spring elements 11, the movable die and stamp parts 3.1, 3.2, 5.1, 5.2 are stretched against the stops 13. The stamp parts 5.1, 5.2 and the plate-shaped punch carrier 7 in this case have recesses (apertures) 14, 15 for the hold-10 supporting push rods 16. The pressure rods 16 penetrate the recesses 14, 15 with play.

Furthermore, the sprung supported Matrizen- and

Stamp parts 3.1, 3.2, 5.1, 5.2 each provided with guides (not shown), the direction of movement of the die and stamp parts 3.1, 3.2, 5.1, 5.2 at

Close and open the forming tool 1 pretend.

Furthermore, serving as Matrizenträger plate 6 and the plate-shaped punch carrier 7 with tappets 17, 18 are provided. The respective plunger 17, 18 penetrates an opening formed in the stamp part 5.2 or die part 3.2 (through hole) 19, 20. The plunger 17, 18 and

Accordingly, the openings 19, 20 are arranged axially offset from one another.

In addition, the plate-shaped Matrizenträger 6 and

Stamp carrier 7 with further stops 21, 22 which face the backs of the linearly displaceable punch parts 5.1, 5.2 and die parts 3.1, 3.2. The the

Tool parts 3.1, 5.1 facing end faces of the stops 21 have in the closed position of the forming tool 1 shown in FIG. 1, a distance AI from the back of the - -

Tool parts 3.1, 5.1, which is less than the distance A2, the rear sides of the tool parts 3.2, 5.2 facing end faces of the stops 22 of the tool parts 3.2, 5.2 have.

When the forming tool 1 is completely closed, the plungers 17, 18 cause a further approach of

Die carrier 6 and punch carrier 7 a moving apart of stamp part 5.2 and die part 3.2, i. a partial opening of the forming tool 1, so that the contact between the component 2 and tool acting surface is partially interrupted (see Figures 1 and 2). The interruption of the contact of the tooling surface 3.21, 5.21 and component 2, i. the partial opening of the forming tool 1, takes place here before and after the press ram with the punch 5 has reached its bottom dead center with respect to the stationary press table 6.

About the ram speed, i. the speed with which the punch 5 is moved in the direction of the plate 6, as well as the distance of the stops 21, 22, the closing time of the punch member 5.2 and the female part 3.2 can be adjusted.

When moving back the plunger 18 close before opening

Matrizenteil 3.1 and stamp part 5.1, the female part 3.2 and the stamp part 5.2 again, creating the area 2.2 of

Component 2, in which a relatively soft structure was produced, is looked up again.

In the exemplary embodiment of the forming tool 1 'according to the invention shown in FIGS. 3 and 4

Die part 3.1 and stamp part 5.1, where the component is to be partially cured, with the die carrier - -

(Press table) 6 or punch carrier 7 rigidly connected.

Die part 3.2 and stamp part 5.2, on which a relatively soft structure in the component 2 is to be set, are on the other hand via cylinder (working cylinder) 23 movably supported against the die carrier 6 and die carrier 7.

The stamp parts 5.1, 5.2 and the plate-shaped punch carrier 7 in turn have recesses (through holes) 14, 15 which are supported by the hold-down 10

Push rods 16 are permeated with play.

Also, the die carrier 6 and the punch carrier 7 with stops 13, 22 are provided which limit the range of movement of female part 3.2 and stamping part 5.2. The stops are formed on brackets 12, where the

Die part 3.2 or stamp part 5.2 also about

Spring elements 11 is supported. The spring elements 11, which are preferably designed as coil springs, engage on the side opposite to the working cylinder 23 of the stamping part 5.2 or die part 3.2.

By means of the working cylinder 23, which can be operated pneumatically, hydraulically or hydropneumatically, the

Interruption of the contact of tool effective area 3.21, 5.21 and component 2 realized in the bottom dead center of the press.

The forming tool 1 'according to Figures 3 and 4 can be operated so that the forming and partial press hardening as desired with or without looking up the workpiece 2, ie with or without re-closing of movable die part 3.2 and movable stamping part 5.2 before opening the firmly on the press table (die carrier 6) or - -

Stamp carrier 7 mounted die part 3.1 and die part 5.1, can be done.

FIG. 5 shows a device for driving and controlling the movable tool elements 3.2, 5.2 of the forming tool 1 'shown in FIGS. 3 and 4. The device comprises a hydraulic cylinder 24 operating in the manner of a pump, which is driven by the press ram of the forming press during each press stroke. Of the

Hydraulic cylinder 24 is preferably filled with oil and connected via a hydraulic line 25 to the working cylinder 23 coupled to the movable die part 5.2 or movable die part. The respective working cylinder 23 here consists of a hydropneumatic cylinder, on whose one piston side the oil flowing through the hydraulic line 25 acts, while on the other side of the piston a compressed gas acts. The gas pressure in the cylinder 23 may, for example, in the closed state of the movable die part 5.2 and the associated movable die part 3.2 be about 50 bar. With the reference numerals 13, 22, the stops of the movable punch member 5.2 are designated in Fig. 5.

In the hydraulic line 25, a valve 26, preferably a check valve is arranged. Further, on the hydraulic line 25 between the check valve 26 and the working cylinder 23, a hydropneumatic pressure accumulator 27th

connected. The gas pressure in the accumulator 27 is in the closed state of stamp part 5.2 and female part 3.2, for example, about 250 bar. The hydraulic line 25 is further provided with a 3/2-way valve 28, from the third port of a valve 26 bridging the return path - - line 29 is connected. In the return line 29, a valve 30 is also arranged, preferably a

Check valve, which acts opposite to the valve 26. Further, between the valve 30 and the 3/2-way valve 28 in turn a hydropneumatic pressure accumulator 31st

connected. The gas pressure in this pressure accumulator 31 is in the closed state of stamp part 5.2 and female part 3.2, for example, about 5 bar. Fig. 6 shows a path-time diagram, which shows an operation of a forming tool according to the invention or the

Forming tool 1 'illustrated in Figures 3 and 4, wherein the contact between the workpiece 2 and the

Contact surfaces of the die and the punch of Umformwerk- tool 1 'is interrupted clocked by the movable

Die part 3.2 and the movable punch part 5.2 several times from the closed position (Fig. 3) in the open position (Fig. 4) and vice versa from the open position to the closed position to be moved. In the example shown in FIG. 6, the clocked contact time is set to approximately 0.2 seconds per second. The contact between the workpiece 2 and the contact surfaces of the movable die part 3.2 and the movable die part 5.2 is thus interrupted in this case by about 0.8 seconds per second. If the Äbkühlrate of the hot-formed workpiece 2 in the region of the cooled die part 3.1 and the punch part 5.1 of the forming tool 1 ', for example, 100 ° C / s, so may clocked interruption of the contact of the workpiece 2 relative to the cooled movable mold part 3.2 and the cooled movable die part 5.2 to a contact time of about 0.2 seconds per second, the average cooling rate in _ _

Area of the female part 3.2 and the stamp part 5.2 can be reduced to about 20 ° C / s.

The measure of the average cooling rate reduction depends essentially on the ratio of the time at which (partially) there is no contact between forming tool 1 'and component 2 to the total cycle time. For the example given above, this means 0.8 s / l s = 0.8. The cooling rate thus drops by about 80% from 100 ° C / s to 20 ° C / s. However, since the cooling of the component does not depend exactly on the times at the same contact pressure, in which partial contact or partial contact between the component and cooled forming tool, the above formula describes only the basic tendency. The times of contact or interruption of contact can be arbitrarily varied within a wide range in the clocked mode of operation according to the invention as shown in FIG. Accordingly, with the described mode of operation, the average cooling rate over time can be reduced from 0 to approximately 100%.

The embodiment of the invention is not limited to the embodiments described above. On the contrary, further variants are conceivable which make use of the invention specified in the appended claims, even in the case of designs differing from those illustrated.

Claims

claims

Forming tool (1, 1 ') for hot forming and partial press hardening of a workpiece made of sheet steel, with a die (3), a for forming the workpiece in a recess (4) of the die (3) insertable punch (5) and a cooling device (8 ), characterized in that the die (3) consists of a first die part (3.1) and at least one second die part (3.2) movable relative to the first die part, while the die (5) consists of a first die part (5.1) and at least a second stamp part (5.2) which is movable relative to the first stamp part, wherein the at least one movable second die part (3.2) and the at least one movable second stamp part (5.2) cooperate with an opening device (17, 18; that the at least one second die part (3.2) and the at least one second stamp part (5.2) contact the workpiece with a shorter closing time than the first die part (3.1) and the first stamp part (5.1).

Forming tool according to claim 1, characterized in that the die parts (3.1, 3.2) are movably connected to a die carrier (6) and the punch parts (5.1, 5.2) are movably connected to a punch carrier (7), wherein the die carrier (6) and the punch carrier (7) each with a plunger (17, 18) are provided, and wherein the plunger (17, 18) in the closed state of the first female part (3.1) and the first stamp member at least one second die part (3.2) and the at least one second die part (5.2) cause.

3. Forming tool according to claim 1, characterized in that the first mold part (3.1) rigid and the at least one second mold part (3.2) movable with a

Matrizenträger (6) are connected while the first

Stamped part (5.1) rigid and the at least one second stamp part (5.2) are movably connected to a punch carrier (7), wherein the die carrier (6) and the

Stamp carrier (7) each having a forward and backward movement causing drive means (23) are provided, and wherein in the closed state of the first die part (3.1) and the first die part (5.1), the drive means (23) moving apart of the at least one second female part (3.2) and the at least one second stamp part (5.2) effect.

4. Forming tool according to claim 3, characterized in that the drive means (23) consists of hydraulic,

pneumatic or hydropneumatic working cylinders are formed.

5. Forming tool according to one of claims 1 to 4, characterized in that the first die part (3.1) and / or the first stamp part (5.1) a cooling device (8) on iron.

6. Forming tool according to one of claims 1 to 5, characterized in that the at least one second

Die part (3.2) and / or the at least one second Stamp part (5.2) a controllable tempering (9, 9.1) on iron.

Forming tool according to claim 6, characterized in that the tempering device (9, 9.1) is a heater.

Forming tool according to one of claims 1 to 7, characterized in that the at least one second die part (3.2) and / or the at least one second die part (5.2) is made of a material with low thermal conductivity or has a surface coating with low thermal conductivity.

Method for hot forming and partial press hardening of a work piece made of sheet steel, in which the

Workpiece is heated prior to forming and then hot formed in a forming tool having a die (3) and a punch (5), wherein the Umformwerk- convincing a cooling device (8), in particular using a forming tool (1, 1 ') after one of claims 1 to 7, characterized in that in

closed state of the forming tool (1, 1 ') of the contact between the workpiece (2) and the contact surfaces of the die (3) and the punch (5) of the forming partially from each other by moving apart a movable die part (3.2) and a movable die part (5.2) a closed position is interrupted in an open position. 10. The method according to claim 9, characterized in that prior to the opening of the forming tool (1, 1 '), the region (2.2) of the workpiece (2), in which the contact between Workpiece and the contact surfaces of the forming tool has been partially interrupted, by moving back the movable die part (3.2) and the punch member (5.2) from the open position to the closed position

is looked up.

11. The method according to claim 9, characterized in that the forming tool (1 ') after the partial press hardening of the formed workpiece (2) is opened without the area (2.2) of the workpiece (2), in which the contact between the workpiece (2) and the contact surfaces (3.21, 5.21) of the forming tool (1) was interrupted in some areas to look up.

12. The method according to claim 9 or 10, characterized in that the contact between the workpiece (2) and the

Contact surfaces of the die (3) and the punch (5) of the forming tool in areas by multiple

Moving apart of the movable die part (3.2) and the movable die part (5.2) from the closed position to the open position and then moving back the movable die part (3.2) and the movable die part (5.2) is interrupted clocked from the open position to the closed position.

13. The method according to claim 12, characterized in that the clocked contact interruption is adjusted so that the sum of the contact times is less than the sum of the contact interruption times.

14. The method according to claim 12, characterized in that the clocked contact interruption is adjusted so that the sum of the contact tents is equal to or greater than the sum of the contact interruption times.

Method according to one of claims 9 to 14, characterized in that the region (2.2) of the workpiece (2), in which the contact between the workpiece (2) and the contact surfaces (3.21, 5.21) of the forming tool (1, 1 ') in regions is interrupted earlier during the

Forming is heated.

16. The method according to any one of claims 9 to 15, characterized

characterized in that during the forming on an edge region of the workpiece (2) a controlled depending on the forming speed hold-down force is exerted.