EP3169462B1 - Moulding tool for producing hot-formed components - Google Patents

Description

The invention relates to a mold for the production of hot-formed components, according to the preamble of claim 1. In today's automotive industry, the comfort for the vehicle occupants increases increasingly through the use of special equipment. These include many electromechanical components such as sensors, motors, actuators, and serve the driver to facilitate the driving task. However, as the comfort increases, so does the vehicle weight. In order to counteract this, it is attempted in the prior art to design the structural components of the body in a weight-reduced manner.
The structural components of the body are not only significantly involved in the stability of the vehicle, but also play a crucial role in safety in the event of a crash. In order to resolve this conflict of interest between reduction of the component weight of structural components while maintaining or realizing high mechanical characteristics, it has proved useful in the past to produce structural components by means of hot forming. Hot forming processes are also described in the literature as mold hardening or press hardening.

For the production of form-hardened components, in particular for the production of body components, two principally different methods are known. In the direct hot forming process, a board is first heated in an oven to a temperature above the austenitizing temperature of the steel and then simultaneously formed and cooled in a tool, i.e., cooled. form-hardened. In the indirect hot forming process, a finished molded and trimmed steel component is first produced from a board by cold forming. This is then heated in a heating plant to a temperature above the austenitizing temperature of the steel and then mold hardened in a tool by rapid cooling. In either hot stamping process, the blank or an already finished and trimmed steel part is thermo-mechanically deformed following heating to the austenitizing temperature in the tool, with thermo-mechanical forming preferably at a temperature above the final austinitization temperature Ac3 (about 830 ° C) between 900 and 1100 ° C takes place. The cooling of the formed workpieces by means of a cooling unit, which is located in a closed tool body. As a result, components with particularly high mechanical properties, in particular with high strengths, can be produced.

The generic patent DE 19723655 B4 shows a method for producing steel sheet products by heating a measured steel sheet, hot working the steel sheet in a pair of tools, hardening the formed product by rapidly cooling from an austenitic temperature while still being held in the pair of tools, and then working the product.
Due to the thermal reaction between the furnace atmosphere and the material of the component, which may be coated or uncoated, scale formation occurs on the surface of the component. This scale formation can already occur in the oven or after the oven. Even a protective gas atmosphere in the oven can not prevent the scale formation but only curb within certain limits. In the hot forming tool, these scale deposits lead to massive wear of the tool, in particular the inserts with integrated cooling systems, which are involved in the shaping of the component. As a result, during the process, the hot forming plant has to be stopped again and again in order to remove the scale deposits from the tool cavities of the hot forming tool by means of compressed air or dry ice. There is a risk that this will lead to contamination of the entire system and to a health impairment of the employees.

Another disadvantage of contamination by scale deposits is seen in the sometimes highly abrasive wear of the mold inserts. In severe cases, the contamination may be so severe that the tools are subjected to cleaning after each pressing, for example by blasting with compressed air or dry ice. Depending on the degree of wear, the inserts are additionally milled or welded in order to restore the original shape contour. Since the cooling lines of the cooling system run a short distance below the effective surface, this repair work can not be repeated as often as desired. After a certain lifetime, these inserts must be completely replaced. This is on the one hand very expensive and on the other hand not sustainable.

Based on this prior art, it is the object of the present invention to provide a mold for the production of hot-formed components, in particular of vehicle components made of sheet metal, with a long service life.

This object is achieved with a mold according to independent claim 1. Advantageous embodiments of the method are specified in the subclaims.

To solve this problem, the invention teaches a mold for the production of hot-formed components, in particular sheet metal parts made of steel, aluminum, magnesium or a combination thereof, with a tool lower part and a tool shell, which are relatively movable to each other and formed with corresponding active surfaces for shaping the component are, wherein at least the active surface of a tool part is formed at least partially coolable. The molding tool may further comprise at least one descaling device. Due to the descaling device, scale and scale dust are removed from the heated sheet-metal part directly at the point of origin or immediately before hot-forming. This avoids the formation of deposits in the mold or on its active surfaces.

In a first embodiment, the descaling device can be designed as a suction and blow-out device. These specially designed blow-suction nozzles generate an air flow which is directed in the direction of the sheet-metal part. Upon impact of the air flow on the sheet metal part of the scale is whirled, or separated from the sheet metal part. By a second air flow, which is also generated by the descaling, the whirled scale is sucked. Optionally, the extracted scale can then be fed to reprocessing plants, big bags, briquetting presses, containers or the like. As a result, a particularly sustainable manufacturing process can be realized.

According to a second embodiment, the descaling device can be designed as an air curtain. Air curtains are also known as air curtains and work on the basis of a combination of blowing and suction.

According to a third embodiment, the descaling device can also be designed as a dry ice cleaning integrated in the tool. With the help of a robot or other mechanical suspension can the sheet metal part are radiated by means of dry ice, for the removal of scale.

In both embodiments, the descaling device can be arranged in the direction of insertion of the component in front of the molding tool. This offers the advantage that the scale is removed even before the introduction of the sheet metal part in the thermoforming mold and thus the risk of contamination of the mold is minimized.

Furthermore, the mold may also comprise a plurality of descaling devices, which are arranged around the active surface of the tool. According to this embodiment, a blowing and suction takes place at several points of the mold. The descaling devices are circumferentially positioned around the mold. As a result, the sheet metal part can be freed of scale formation from several sides at the same time. Furthermore, the descaling devices can also be directed directly onto the molding tool, so that the flows generated thereby also act directly on the active surface of the mold halves. If a transfer of scale from the sheet metal part has taken place on the mold, so that the scale can be removed again and thereby the mold to be cleaned.

In all described embodiments, the descaling device can be arranged on the upper tool part or on the lower tool part or on both tool parts.

In addition, the descaling device may be intermittently operable, being turned off at least in a fully closed state of the molding tool and turned on in a fully opened state of the molding tool. Thus, the blowing and suction is controlled such that only if the sheet metal part or the effective surface of the mold can be reached by the currents also an energy-consuming cleaning is performed. Advantageously, this increases the sustainability of the manufacturing process.
The descaling device can be switched on after each forming operation or after a predetermined number of forming operations. This offers the advantage that deposits can be counteracted by tinder preventive.
Alternatively, the descaling device can be activated as a function of the tool state. Blowing and suction of scale can be controlled by scale of tool contamination by scale. The degree of contamination can be detected by a camera system of the tool.
Furthermore, air ducts can be provided in at least one tool part, via which air can be applied to the active surface of the tool part. These fine air ducts can assist the blow-out process so that a particularly thorough scale removal can be ensured.
The invention is explained in more detail below with reference to the description of the figures.

Fig. 1

eine Schnittansicht durch ein Formwerkzeug, gemäß einer ersten bevorzugten Ausführungsform der Erfindung,

Fig. 2

eine Schnittansicht durch ein Formwerkzeug, gemäß einer ersten bevorzugten Ausführungsform der Erfindung, bei der Luftkanäle in den Werkzeughälften angeordnet sind, und

Fig. 3

eine Draufsicht auf ein Werkzeugunterteil.

It shows in a schematic representation

Fig. 1

a sectional view through a mold, according to a first preferred embodiment of the invention,

Fig. 2

a sectional view through a mold, according to a first preferred embodiment of the invention, are arranged in the air ducts in the mold halves, and

Fig. 3

a plan view of a tool base.

Fig. 1 shows a mold 10, which is used in presses for hot forming sheet metal blanks to sheet metal components 17. The mold 10 has a lower mold half 12u, which rests on a base plate 11. The lower mold half 12u cooperates with an upper mold half 12o. The mutually facing active surfaces of the upper mold half 12 o and the lower mold half 12 u are formed correspondingly, so that they act as a die and die of a press tool. At the in Fig. 1 illustrated example, the tool half 12o is designed as a punch and the tool half 12u as a die. Without departing from the scope of the invention, the upper and lower mold halves can be reversed in their arrangement, such that the upper tool acts as a die and the lower tool acts as a punch. The upper mold half 12o and the lower mold half 12u are movable relative to each other. In the Fig. 1 shown mold halves 12o, 12u can be moved apart and again together. When the mold halves move together, a piece of sheet metal or a sheet metal blank is inserted between the mold halves, and is encompassed and shaped by the active surfaces. The in Fig. 1 shown state corresponds to an open position of the tool halves 12u, 12o in a forming process in which the component 17 is completely reshaped and can be removed from the mold 10.

In the lower mold half 12u an insert 13 is provided, in which a cooling system having a plurality of cooling channels or cooling lines 14 is integrated. The use of such inserts 13 offers, on the one hand, the advantage that different component contours can be embossed with a lower forming tool 12u in that the insert 13 can be replaced in accordance with the desired component shape. The cooling lines 14 extend substantially parallel to the surface of the component 17 and thus also substantially parallel to the effective surface of the Mold halves 12u, 12o. The cooling lines 14 thus follow the component surface at a certain distance in the insert 13 of the lower mold half 12u. With the cooling channels a targeted cooling of the component 17 in the region of the cooling channels 14 is made possible, so that in this area a microstructure is realized in the component, with high mechanical strength.

At the tool halves 12u, 12o descaling devices 18, 18 'are provided, wherein in each case a descaling 18' on the upper die 12o and a descaling 18 is arranged on the lower tool part 12u. Both descaling devices are connected via a common line 19. Compressed air can be supplied via this line, which is then sprayed onto the component 17 or from the sheet metal part which has not yet been formed. At the same time, the dissolved zinc dust is collected via another air flow and extracted with the descaling device. The contaminated with Zunderstaub air is removed via the line 19 and optionally fed to a reprocessing plant. How out FIG. 1 it can be seen, the descaling device is in the direction of insertion of the sheet metal part in front of the mold. The sheet metal part is in FIG. 1 introduced from the left into the thermoforming mold and thus cleaned before introduction between the tool halves 12u, 12o of scale. If one of the descaling devices 18, 18 'is designed as an air curtain, it can extend over the entire length of the sheet metal part such that when the sheet metal part is introduced, it is completely cleaned of scale.

In FIG. 2 is a mold shown with a to the in FIG. 1 illustrated analog structure. In addition, the mold halves 12u, 12o have air ducts 15 that are fluidly connected to a manifold system 16. Compressed air is thus introduced via the connection system 16, and distributed to the air lines 15. At the in Fig. 1 upper end of the air channels 15 are outlets or openings provided, from which the compressed air flows into the area between the mold halves 12u and 12o. These air ducts 15 can be manufactured in any desired pitch and diameter and support the action of the descaling device 18, 18 '. FIG. 2 shows a closed position of the mold 10. In this state, the sheet metal part 17 is hardened. The descaling device 18 is switched off.

In the figures, only the lower mold half 12u is provided with cooling channels 14, wherein air channels 15 are provided in the tool upper part 12o and the tool lower part 12u. In other embodiments of the invention, alternatively, the arrangement of the cooling system, i. the connection system 16 and the cooling channels 15 may also be arranged only in one of the tool halves 12u, 12o. In a further alternative embodiment, cooling channels 14 may be provided both in the upper tool half 12o and in the lower tool half 12u.

FIG. 3 shows a plan view of a lower tool part 12u of the mold 10. Beispielshaft here is the effective surface formed as a B-pillar. Alternatively, the active surface may be formed in the form of other vehicle components or vehicle structural components. In FIG. 3 the descaling devices 18 according to a second embodiment of the invention are formed as individual suction and blow-out devices and arranged essentially around the effective surface of the tool lower part 12u. The descaling devices 18 are connected via a common supply and discharge system 19. With reference to in FIG. 2 shown air ducts 15 can also in the embodiment according to FIG. 3 be provided.

In summary, the advantages of the invention will be enumerated below. With the aid of the descaling device, optimal plant availability can be achieved by means of virtually scale-free and dust-free Working environment. In addition, an improvement in occupational safety is achieved and the health burden on workers is reduced. Time and cost savings result from the fact that scale residues do not have to be manually removed by workers. This is accompanied by an increase in system speed due to the integrated extraction of the scale residues. On the component side, a quality improvement can be realized through high quality assurance. By minimizing the internal dust load on the tool side, the service life of the processing tools can be considerably extended (cooling inserts). Due to the extraction system now installed directly inside the production line, the measuring instruments (thermographic camera systems) are no longer polluting and thus considerably more precise measurements can be carried out during production, which ultimately results in a significant improvement in quality. The machine downtimes can be significantly reduced due to the further apart cleaning cycles.

LIST OF REFERENCE NUMBERS

10

mold

11

Tool base plate

12u

Tool part

12o

Upper die

13

tool insert

14

cooling lines

15

air ducts

16

feed

17

component

18

descaling

19

line system

Claims (10)

1. A forming die (10) for producing hot-formed components (17), especially shaped sheet metal parts made of steel, aluminium, magnesium or a combination thereof, with a lower die part (12u) and an upper die part (12o) which are movable relative to each other and which are designed with corresponding effective surfaces for shaping the component (17), wherein at least the effective surface of a die part (12u, 12o) is designed to be coolable at least in portions,
   characterised by
   at least one descaling means (18, 18').
2. A forming die according to Claim 1, characterised in that
   the descaling means (18, 18') is designed as an extracting and blowing-out means.
3. A forming die according to Claim 1 or Claim 2, characterised in that
   the descaling means (18, 18') is designed as an air curtain.
4. A forming die according to one of Claims 1 to 3, characterised in that
   the descaling means (18, 18') is arranged ahead of the forming die in the direction of introduction of the component (17).
5. A forming die according to one of Claims 1 to 3, characterised in that
   the forming die (10) comprises a plurality of descaling means (18, 18') which are arranged around the effective surface of the die.
6. A forming die according to one of the preceding claims, characterised in that
   the descaling means (18, 18') is arranged on the upper die part (12o) or on the lower die part (12u) or on both die parts (12u, 12o).
7. A forming die according to one of the preceding claims, characterised in that
   the descaling means (18, 18') can be operated intermittently, being switched off at least in a completely closed state of the forming die and being switched on in a completely opened state of the forming die.
8. A forming die according to Claim 7, characterised in that
   the descaling means (18, 18') is switched on after each forming operation or after a predetermined number of forming operations.
9. A forming die according to Claim 8, characterised in that
   the descaling means (18, 18') is activated dependent on the die state.
10. A forming die according to one of the preceding claims, characterised in that
    air ducts are provided in at least one die part (12u, 12o), via which ducts air can be applied to the effective surface of the die part.

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