EP3088092B1 - Hot forming and press hardening tool and method for operating the hot forming and press hardening tool - Google Patents

Description

The present invention relates to a hot forming and press hardening tool according to the features in the preamble of claim 1.

The present invention further relates to a method for operating the hot-forming and press-hardening tool according to the features in claim 9.

For the production of components, in particular motor vehicle components, it is known to machine sheet metal blanks by means of forming processes, in particular by means of press forming in a tool. As a result Blechumformbauteile be prepared for the body shop, structural components or even sheet metal skin components. The Blechumformbauteile are preferably made of steel materials, but also made of light metal materials.

In recent years, in particular, the hot forming and press-hardening technology has become established, by means of which hardenable steel alloys are processed. In this case, the degree of shaping freedom of a sheet metal blank can be increased by a previous heating, in particular to above AC3 temperature, whereby highly complex, three-dimensionally shaped components are produced. So then the component remains in the tool and is cured under at least partially martensite by rapid cooling, so that a component with at least partial high-strength, especially very high-strength material properties is produced. As a result, components are produced that are lighter but also harder than components made from a conventional steel alloy that have been cold worked.

For this purpose, however, it is particularly necessary that when using a press forming the resulting at bottom dead center, thus at complete closing of the press forming mold cavity has a sufficient contact with the sheet metal circuit-formed sheet to a good heat transfer from the still warm formed in the cooling to be performed for quenching Sheet metal to enable the forming tool. The heat is then removed by, for example, a cooling medium flowing through cooling passages of the forming tool.

In the production and design of a hot forming and press hardening tool this is taken into account, so that in principle the greatest possible contact with the system is ensured. However, then occur during operation of the hot forming and press hardening tool thermal expansion and shrinkage of the tools themselves. Furthermore, the provided batches of boards to be processed on production fluctuations, so that even here a few tenths of a millimeter can cause that in some areas a no longer sufficient contact with the plant is made. In addition, the molding surfaces are subject during operation to produce several thousand components, a mechanical wear, which can also lead to a Nichtanlagenkontakt.

This is for example from the DE 10 2013 011 419 A1 a forming tool is known, wherein a forming tool is formed in two parts and is moved by a second pressing force, applied by means of an active medium transversely to the press direction. However, a disadvantage is the much more expensive construction and increased effort to operate such a hot forming and press hardening tool. The document DE 10 2010 027 554 A1 discloses a hot forming and press hardening tool according to the preamble of claim 1. It is therefore an object of the present invention to provide a hot working and press hardening tool which is simple to manufacture and inexpensive and mechanically easy to operate, but which ensures that as much as possible in press hardening extensive system contact is provided especially in the area of vertically extending contact surfaces.

The above object is achieved with a hot forming and press hardening tool according to the features in claim 1.

The procedural part of the object is further achieved according to the invention with the features in claim 9.

Advantageous embodiments of the present invention are described in the dependent claims.

The hot-forming and press-hardening tool for producing sheet-metal forming components from a steel alloy is suitable for producing at least partially high-strength properties on the sheet-metal forming component, preferably for shaping and then hardening the entire sheet-metal component. It has for this purpose an upper tool with at least one mold segment and a lower tool with at least one mold segment, wherein the upper tool and the lower tool are movable towards each other to form a mold cavity in a Pressenhubrichtung. Upon reaching the bottom dead center of the hot forming and press hardening tool of the mold cavity between the upper tool and lower tool or between the mold segments of upper tool and lower tool is thus formed. According to the invention, the hot-forming and press-hardening tool is characterized in that the mold segment of the upper tool and / or the mold segment of The lower tool is divided into two parts and is movable transversely to the press stroke direction by means of a spreader device coupled to the upper tool and / or lower tool in at least one movement direction.

According to the invention, in particular, the spreading device itself acts exclusively on the mold segment, in particular by means of an expanding wedge, also referred to below as an expanding die. As a result, a structurally simple, robust and at the same time effective construction is realized, which keeps the operating costs of the hot-forming and press-hardening tool according to the invention low.

It is thus possible with the hot forming and press hardening tool according to the invention during the closing movement and / or reaching the bottom dead center of the hot forming and press hardening tool to allow a displacement of a mold segment transversely to the Pressenhubrichtung, so that even with vertically oriented contact surfaces sufficient plant contact or Surface pressure between shaping inner lateral surface and outer lateral surface of the mold segments of the formed sheet metal blank is made. With passage of a cooling medium and execution of the press hardening, a high cooling rate can thus be produced in a production-safe manner, which is why the rejects are minimized while shortening the cycle time for press hardening. In particular, the tool according to the invention is suitable for the production of thermoformed and press-hardened components which have a forming angle of 90 ° to 110 °, preferably 90 ° to 100 ° and particularly preferably 90 ° to 95 °.

Particularly preferably, the spreading device itself is designed as a spreading die, wherein the expanding die is fixed in position either on the upper tool or on the lower tool. Also, in each case a spreading punch can be arranged formed both on the upper tool and on the lower tool. These are then fixed in position and thus rigidly coupled in the press lifting direction and transversely to the press lifting direction with the upper tool or the lower tool. Alternatively, it is advantageously possible for the spreading punch to be mounted in a relatively movable manner on the upper tool and / or on the lower tool. By an actuator, for example by an additional hydraulic actuator, a kinematic coupling with the Pressenhubvorrichtung or by another actuator, for example, an electromechanical actuator then the spreading can be moved again relative to the upper tool and / or the lower tool. In particular, it is possible here, for example, after reaching the bottom dead center in the movement in Pressenhubrichtung the spreader again minimal to move, so as to build a higher contact pressure across the Presshubrichtung.

Furthermore, the at least two mold segments on the upper tool and / or the at least two mold segments can be mounted on the lower tool relatively displaceable in the press lifting direction. It is also possible to store the at least two mold segments in the press stroke direction in a slide-rigid manner on the upper tool or the lower tool. It is important, however, that the at least two mold segments are mounted in a direction of movement transversely to the Pressenhubrichtung relatively displaceable, which form on their side facing away from the forming mold cavity a Spreizhohlraum and the Spreizstempel moves into the Spreizhohlraum, so that move the mold segments of the Spreizstempel outward , in a direction of movement transverse to the Pressenhubrichtung. Thus, by closing in the press lifting direction, contact with the system and / or surface pressure on the unformed sheet metal blank is ensured in the sections which are essentially horizontal and, due to the relative movement of the forming segments transversely to the press lifting direction, also a sufficient contact surface or surface pressure in the sections which essentially run vertically.

Furthermore, particularly preferably, the mold segments of the lower tool and / or the mold segments of the upper tool are mounted on the upper tool and / or the lower tool via return means. When the hot forming and press hardening tool is opened, the mold segments are returned to a starting position. The restoring means each couple the mold segments of the upper tool with each other or the two mold segments of the lower tool with each other. The restoring means can be oriented both in the press lifting direction, which is necessary in particular in the case of press sections that are relatively displaceable in the press lifting direction. However, the return means are preferred in particular Horizontal direction acting, so that two in the horizontal direction, thus spread apart across the press stroke and spread apart mold segments are contracted by a return means, for example in the form of a return spring and here in particular a tension spring when moving out of the expansion.

Furthermore, particularly preferably, the molding segments have tempering channels for the passage of a cooling medium, wherein the tempering channels are coupled to the upper tool and / or the lower tool via elastic and / or displaceable connections. In particular, these are elastic hose connections which are, for example, compressed or stretched or bent in order to carry out the relative movement, in particular transversely to the press stroke direction. In the context of the invention, however, may also be sliding connections, for example in the form of a sliding seat or for example a sliding sleeve, so that when performing a relative movement in an axial direction transverse to the Pressenhubrichtung the sliding sleeve compensates the relative change in length, but at the same time gives the possibility, a fluid-tight Cooling medium supply the temperature control channels in the respective mold segment. In addition, it is possible to provide isolation in addition to a cooled by coolant mold segment and adjacent to the insulation, a heated mold segment to produce components with locally targeted uncured areas.

The hot-forming and press-hardening tool is characterized in particular by the fact that the mold segments of the upper tool are formed as a two-part die, which are coupled to each other via a return means to the Pressenhubrichtung and that the mold segment of the lower tool is formed as retracting into the die punch, wherein laterally on the punch wedge slide are arranged and the wedge slide are displaceable in the execution of the press stroke through the die transverse to the Pressenhubrichtung outwards.

Further particularly preferably, stop means and / or spacer means are provided on the upper tool and / or on the lower tool. As a result, in particular the relative movement is limited transversely to the Pressenhubrichtung. In particular, a relative movement transversely to the Pressenhubrichtung up to 1 mm, in particular up to 0.5 mm possible. Further preferably, stop means are provided such that in a possible relative movement in Pressenhubrichtung when reaching the bottom dead center and the die segment pushes in the press stroke on the stop means, so that at the latest at bottom dead center in Pressenhubrichtung the complete shaping is completed.

The present invention further relates to a method for operating the aforementioned hot-forming and press-hardening tool, wherein the method is characterized in that during movement and / or at bottom dead center, the at least one mold segment of the upper tool or the lower tool is moved transversely to the Pressenhubrichtung so in that a respective +/- 20 °, preferably between +/- 10 ° and particularly preferably +/- 5 ° oriented to Pressenhubrichtung oriented portion extending in the mold cavity, thus having a substantially vertically oriented extending portion of the mold cavity has a system contact with a formed sheet metal blank which has at least 80%, preferably 90%, in particular 95% of the surface pressure with respect to a section of the formed sheet metal blank which is formed in the mold cavity, which extends substantially horizontally, thus transversely to the press stroke direction. Thus, it is ensured that preferably a plant contact with substantially uniform surface pressure is present on the entire component, whereby the press hardening can be carried out with high precision.

Particularly preferably, with the hot forming and press hardening tool according to the invention, motor vehicle pillars, transmission tunnels, bumpers, motor vehicle rockers or even reinforcing components for motor vehicles can be produced. In particular, the hot-forming and press-hardening tool is suitable for components having an elongated section which is U-shaped in cross-section, so that the web of the U-shape experiences system contact with the molding segments by a surface pressure in the press stroke direction and the leg protruding from the web to form the U-shape by the direction of movement transverse to the Pressenhubrichtung experiences sufficient contact with the mold segments. In particular, a hardness or tensile strength of web and legs can thus be at an approximately the same level with particularly short cycle times for press hardening be achieved. These are less than 20 s, preferably less than 10 s, for insertion, shaping, holding and removal.

Figur 1a und b

die Problemstellen sowie einen aus dem Stand der Technik bekannten Lösungsvorschlag,

Figur 2

eine erste erfindungsgemäße Ausgestaltungsvariante mit Spreizstempel am Oberwerkzeug,

Figur 3

eine zweite Ausgestaltungsvariante mit relativbeweglichem Spreizstempel am Oberwerkzeug,

Figur 4

eine vierte erfindungsgemäße Ausgestaltungsvariante mit geteilter Matrize am Oberwerkzeug und in diese einfahrenden Stempel am Unterwerkzeug,

Figur 5

einen Querschnitt durch eine mit dem erfindungsgemäßen Umformwerkzeug hergestellte Kraftfahrzeugsäule mit hutförmigem Profil und

Figur 6

einen Querschnitt durch mit dem erfindungsgemäßen Warmumform- und Presshärtewerkzeug hergestellte Kraftfahrzeuge mit W-förmigen Profil.

Further advantages, features, characteristics and aspects of the present invention will be discussed in the following description. Preferred embodiments are shown in the schematic figures. These are for easy understanding of the invention. Show it:

FIGS. 1a and b

the problem areas and a proposed solution known from the prior art,

FIG. 2

a first embodiment variant according to the invention with spreading punch on the upper tool,

FIG. 3

a second embodiment variant with a relatively movable spreader on the upper tool,

FIG. 4

a fourth embodiment variant according to the invention with a split die on the upper tool and in these inward-moving punches on the lower tool,

FIG. 5

a cross section through a manufactured with the forming tool according to the invention motor vehicle pillar with hat-shaped profile and

FIG. 6

a cross section through manufactured with the hot stamping and press-hardening tool according to the invention vehicles with W-shaped profile.

In the figures, the same reference numerals are used for the same or similar components, even if a repeated description is omitted for reasons of simplicity.

FIG. 1a shows a known from the prior art forming tool 1 comprising an upper tool 2 and a lower tool 3, which retract one another while forming a mold cavity 4 in Pressenhubrichtung 5. For this purpose is a sheet metal plate 6 is inserted into the open mold, which is formed into the sheet metal forming component 7. The remaining after completion of the molding sections of the component, which run in Pressenhubrichtung 5, thus vertically oriented, thereby may have a lower plant contact or a lower surface pressures even up to an air gap 8, which is why here a lower cooling rate when performing a press hardening and / or a lower forming accuracy is recorded. From the prior art is so far according to FIG. 1b a solution is known in which a movable additional segment 9 is provided by applying an external second pressing force 10 across the Pressenhubrichtung 5 for a system contact.

The solution according to the invention looks according to this FIG. 2 a hot forming and press-hardening tool 11, in which two mold segments 13.1, 13.2 are mounted on an upper tool 12 relatively movable to the upper tool 12 and on a lower tool 14, a mold segment 15 is mounted in parallel. When carrying out the deformation in the press lifting direction 5, the upper tool 12 is thus lowered onto the lower tool 14 and the mold segments 13.1, 13.2, 15 are moved toward each other in the press lifting direction 5 such that they reach the bottom dead center (right image plane of FIG FIG. 2 ) form a mold cavity 4. In this case, both mold segments 13.1, 13.2 of the upper tool 12 are mounted relatively movably in the press lifting direction 5, but also additionally mounted in a direction of movement 16 transversely to the press lifting direction 5. For this purpose, a fixed to the upper tool 12 Spreizstempel 17 moves into a Spreizhohlraum 18 on the back of the mold segments 13.1, 13.2 of the upper tool 12 and ensures due to a conical or tapered course by mechanical contact system and consequent spread or displacement for a spreading apart or Moving apart of the mold segments 13.1, 13.2 of the upper tool 12 in the direction of movement 16 transversely to the Pressenhubrichtung 5. So that the full press force 10 is transmitted in Pressenhubrichtung 5, stop elements 19 between the upper die 12 and mold segment 13.1, 13.2 are incorporated, which at bottom dead center to a positive plant contact to lead. Thus, the mold segments 13.1, 13.2 are returned to the initial state, return means 20 are provided, which shown here a relative movement in Execute Pressenhubrichtung 5 and not shown return means 20 which the shape segments 13.1, 13.2 contract each other, as soon as the spreading 17 is moved out of these.

A second embodiment variant is in FIG. 3 represented, wherein also here two mold segments 13.1, 13.2 are mounted relatively movable in a direction of movement 16 transversely to the Pressenhubrichtung 5. However, the mold segments 13.1, 13.2 are fixed in parallel to the upper tool 12 in the press lifting direction 5. In this case, the spreader 17 can perform a relative movement to the upper tool 12 and in particular in Pressenhubrichtung 5, so that at any time during the closing movement or when reaching the bottom dead center of the spreading 17 relative to the upper tool 12 by an actuator 21, for example a hydraulic ram , is movable. The spreader 17 then calls again at its oblique contact surfaces 22 with the Spreizhohlraum 18 of the mold segments 13.1, 13.2 the movement of the mold segments 13.1, 13.2 in the direction of movement 16 transversely to the Pressenhubrichtung 5, so that even in the vertically oriented sections between mold segment and formed sheet metal plate. 6 a sufficient contact with the system and / or a sufficient surface pressure is achieved.

FIG. 4 shows an alternative embodiment variant of the present invention. Here, a two-part die 23.1, 23.2 is formed on the upper tool 12, which moves in a slide-rigid with the lower tool 14 connected punch 24. On the punch 24 edge-mounted wedge slide 25 are arranged, which are moved when retracting the die 23.1, 23.2 in the direction of movement 16 transversely to the Pressenhubrichtung 5 to the outside. The wedge sliders 25 are bounded on the outside by stop elements 19 and controllable with them via a force means 26, in particular in the form of a compression spring and / or a hydraulic system such that, on the one hand, a restoring force is provided, and, on the other hand, if the stop element 19 is not in a form-locking manner Surface pressure is achieved at the outer contact surfaces. The die parts 23.1, 23.2 can also be moved relative to each other in the direction of movement 16. They are pressed together by a spreading spring 27.

In the FIGS. 2 to 4 are each indicated in the die 24, die 23.1, 23.2 or mold segment 13.1, 13.2, 15 tempering 28 for the passage of a tempering, in particular a cooling medium. These can be evenly distributed, but also be arranged only partially, so that a targeted temperature control of the formed component can be performed.

FIG. 5 shows a cross section through a motor vehicle pillar according to the invention manufactured comprising a web 29 and extending from the web 29 leg 30 and a again projecting from the legs 30 flange 31. Between the web 29 and the legs 30 is an angle α of preferably 90 ° to 100 °, in particular 90 ° to 95 ° and particularly preferably formed by about 90 °. The strength of the web 29 and / or the flanges 31 in Pressenhubrichtung 5, characterized in that they are made in Pressenhubrichtung, preferably have a full-surface contact with the system and thus achieve optimal heat transfer when carrying out the press hardening. The legs 30 are made by preferably a plant contact with a direction of movement 16 transversely to the Pressenhubrichtung 5. According to the invention, it is possible that the tensile strength of the legs 30 has at least 90% of the tensile strength of the web 29 due to the press-hardening with the hot-forming and press-hardening tool 11 according to the invention. Preferably more than 95% of the tensile strength. In particular, the tensile strength of the legs 30 is greater than or equal to 98% of the tensile strength of the web 29th

FIG. 6 shows a second embodiment variant of a sheet metal forming component 7 produced according to the invention, which is produced with the hot forming and press-hardening tool 11 according to the invention. This has a W-shaped cross section, which is why the web 29 is formed in two parts and thus four legs 30 are formed. In particular, the sheet metal forming component 7 is according to FIG. 6 on a forming tool 1 according to FIG. 4 produced, in turn, the above-mentioned ratios of the set with the press hardening tensile strength of web 29 to leg 30 are formed.

Reference numerals:

1 -

forming tool

2 -

upper tool

3 -

lower tool

4 -

mold cavity

5 -

Press stroke direction

6 -

sheet metal blank

7 -

Blechumformbauteil

8th -

air gap

9 -

additional segment

10 -

Pressing force across to 5

11 -

Hot forming and press hardening tool

12 -

upper tool

13.1 -

Shape segment to 12

13.2 -

Shape segment to 12

14 -

lower tool

15 -

Form segment to 14

16 -

Direction of movement across 5

17 -

Spreizstempel

18 -

Spreizhohlraum

19 -

stop element

20 -

Return means

21 -

actuator

22 -

contact area

23.1 -

1st part of the matrix

23.2 -

2nd part of the matrix

24 -

stamp

25 -

wedge slide

26 -

power means

27 -

splay

28 -

tempering

29 -

web

29.1 -

partial web

29.2 -

partial web

30 -

leg

31 -

flange

α -

angle

Claims (9)

1. Hot forming and press hardening tool (11) for producing formed sheet components (7) with at least partially high-strength properties, comprising an upper tool (12) with at least one mould segment (13.1, 13.2) and a lower tool (14) with at least one mould segment (15) wherein the upper tool (2) and the lower tool (3) are movable towards each other forming a mould cavity (4) in a pressing stroke direction (5) wherein tempering channels (28) for conducting a cooling medium are provided in at least one mould segment (13.1, 13.2, 15) wherein the mould segment (13.1, 13.2) of the upper tool (12) and/or the mould segment (15) of the lower tool (14) is at least partially divided into two, characterised in that the mould segment (13.1, 13.2) is movable in at least one movement direction (16) transverse to the pressing stroke direction (5) with an expansion device coupled to the upper tool (12) and/or the lower tool (14).
2. Hot forming and press hardening tool according to claim 1, characterised in that the expansion device is an expansion punch (17) wherein the expansion punch (17) is fixed in position on the upper tool (12) and/or the lower tool (14) or the expansion punch (17) is mounted so as to be relatively movable on the upper tool (12) and/or the lower tool (14).
3. Hot forming and press hardening tool according to claim 2, characterised in that the at least two mould segments (13.1, 13.2) on the upper tool (12) and/or the at least two mould segments on the lower tool (14) are mounted so as to be displaceable relative to each other in at least one movement direction (16) transverse to the pressing stroke direction (5) and form an expansion cavity (18) wherein the mould segments (13.1, 13.2, 15) are moved outwards from the expansion punch (17) when the expansion punch (17) is moved into the expansion cavity (18).
4. Hot forming and press hardening tool according to any one of claims 1 to 3, characterised in that the mould segments (13.1, 13.2) are mounted on the upper tool (12) and/or the lower tool (14) via restoring means (20) and/or in that the mould segments (13.1, 13.2, 15) are coupled to each other via a restoring means (20) such that mould segments (13.1,13.2,15) are returned into a starting position when the hot reforming and press hardening tool (11) is opened.
5. Hot forming and press hardening tool according to any one of claims 2 to 4, characterised in that the expansion punch (17) is movable relative to the upper tool (12) and/or the lower tool (14) via an actuator (21).
6. Hot forming and press hardening tool according to any one of claims 1 to 5, characterised in that tempering channels (28) for conducting the cooling medium are coupled to the upper tool (12) and/or the lower tool (14) via elastic and/or movable connections and/or in that a heating segment is provided in a mould segment (13.1, 13.2, 15).
7. Hot forming and press hardening tool according to any one of claims 1 to 6, characterised in that the mould segments (13.1, 13.2) of the upper tool (12) are formed as a die (23.1, 23.2) divided into two via which a restoring means (20) and/or an expansion spring (27) are coupled transverse to the pressing stroke direction (5) and in that the mould segment (15) of the lower tool (14) is formed as a punch (24) moving into the die (23.1, 23.2) wherein gate valves (25) are arranged laterally on the punch (24) and the gate valves (25) are displaceable outwards transverse to the pressing stroke direction (5) when the pressing stroke is performed by the die (23.1, 23.2).
8. Hot forming and press hardening tool according to any one of claims 1 to 7, characterised in that stop means and/or spacing means are provided and/or in that the mould segments (13.1, 13.2, 15) are mounted in the pressing stroke direction (5) so as to be moveable relative to the upper tool (12) and/or to the lower tool (14).
9. Method for operating a hot forming and press hardening tool according to at least claim 1, characterised in that the at least one mould segment (13.1, 13.2, 15) is moved transverse to the pressing stroke direction (5) during the closing movement and/or in the lower dead centre of the hot reforming tool such that a section of the mould cavity (4) running orientated to the pressing stroke direction (5) at plus/minus 20°, preferably plus/minus 10° comprises a bearing contact with a formed sheet blank (6) which corresponds to at least 80%, preferably 90% and in particular 95% of the surface pressure of the substantially horizontally-orientated sections of the mould cavity (4).

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