EP2989220B1 - Device for press hardening components - Google Patents

Description

Press hardening, which is also known as "thermoforming", is a process for hot forming components, in particular sheet metal materials. In this case, a combination of heat treatment, shaping and optionally controlled cooling takes place.

A common area of application for press hardening processes is, inter alia, in the field of automobile production, for example in connection with automotive lightweight construction concepts. Here it is often used for forming coated metallic components, so on the one hand, the components do not scale during the heat treatment and on the other hand increases the durability of the tools or corrosion protection is guaranteed in subsequent use.

The components fed to the press-hardening are, for example, coated with an aluminum-silicon alloy. With the use of such coatings, common devices during the heat treatment in the oven often lead to a thermochemical impairment of individual components of the furnace. Particularly affected are components of a transport device, which serves to convey the components through the furnace and thus come into direct contact with the components. This leads to high costs for maintenance and servicing.

If the components to be formed have a contact-sensitive coating, such as a zinc coating, contact with, for example, the transport device of the furnace may damage the coating. A contact of a zinc coating with another, for example, rough, surface, z. B. with rolls of a roller hearth furnace or with shelves of a chamber furnace can be damaged as a result of the friction occurring.

In the known method for press hardening, the components are first heated in the oven to a temperature of, for example, about 950 ° C and then transported in a press. There occurs during the shaping in the press usually a controlled cooling. The furnace is usually designed as a roller hearth furnace or a chamber furnace, wherein the roller hearth furnace, the components are passed through a roller conveyor through the oven and placed in the chamber furnace with a manipulator in the oven. Other types of furnaces, such as walking beam ovens and chain-carrier ovens, have not been successful so far.

DE 10 2009 050 879 B3 discloses a method and apparatus for board heating. The blanks are heated in a pusher furnace in several process steps to effect certain material properties for subsequent process steps. Here, an induction method is used to transfer heat energy to the boards. The process steps provide that the boards are heated in several stages and are supplied to the further process step, such as a press or mold hardening after heating. For this purpose, the device has a conveyor system, which consists of several chains of ceramic, on which the boards are positioned.

According to WO 2014/053 550 a transport device has a tempering chamber in which a component is moved vertically with a displacement device. The component is picked up for removal from a furnace by the shuttle when it is in a pickup position. For passing on to the further processing device, the traversing device is in a dispensing position. From this dispensing position, the component is conveyed by means of a conveying device from the temperature-control chamber or the displacement device to the further-processing device.

So that the components reach the press with the least possible loss of temperature, the components should be transferred as quickly as possible from the furnace to the press. This is usually by means of a manipulator, such as a robot, which removes the components directly from the oven or grips the components passed through the oven with a transport device, such as the roller conveyor, and transfers them to the press. The manipulator then also serves to bring the component before insertion into the press, for example by turning in the correct position.

Both the transport between the oven and the press as well as making the manipulations are associated with a process-related difficult to reduce time and thus have the consequence that the component cools before the beginning of the molding process or additionally scaled in the case of uncoated components. Accordingly, the components in the oven must be brought to a higher temperature than would actually be necessary for the subsequent molding process in the press. This degrades the energy efficiency of the process. In addition, by reacting the components with the manipulator increases the risk that the coating will be damaged by mechanical contact.

In the known methods, therefore, a high degree of automation is required. Due to the necessary manipulations, not only can the coating be damaged, but it is also scarcely possible to reduce the cycle times, as is advantageous for efficient operation.

The invention is therefore based on the object to overcome these and other disadvantages of the prior art and to provide a device for the press-hardening of components, which allows rapid, non-destructive, energy and cost-efficient machining of the components. In particular, a thermochemical attack of the coating of the components on the means of a transport device should be excluded as far as possible and a contact damage of the coating should be avoided as far as possible. In this case, an implementation of the components from the oven in the press should be done as quickly as possible in order to prevent unnecessary cooling. Furthermore, a method for press hardening of components using an apparatus according to the invention is to be made available.

Main features of the invention are set forth in the characterizing part of claim 1 and claim 12. Embodiments are the subject of claims 2 to 11.

In a device for press-hardening of components with at least one furnace, a furnace downstream of the press and a transport device is inventively provided that means for transporting the components are slidably mounted in the transport device, wherein the means with the components along the transport device through the furnace and are movable in the press, wherein the transport device between the furnace and the press is continuous and wherein the transport of the components from the oven to the press is tamper-free feasible.

According to the invention is therefore intended to bring the components by the same means not only in the oven, but also to pass through the oven and to proceed in the press. Additional manipulators for converting the components between the oven and the press are therefore not required. Accordingly, not only a manufacturing cost of the device is reduced, but also shortens possible cycle times, since the components can be transported faster from the oven to the press. The components can be contacted by the means in areas which either have no coating or lie outside a later range of use of the component. These areas can be removed, for example, in the press or after the pressing process. The area of use of the components is thus passed through the furnace and into the press without contact, so that even contact-sensitive coatings can be processed without difficulty.

In this case, the transport device may have sections of different transport speed. For example, a lower transport speed is desired in carrying out the means with the components through the furnace, as for example when transporting from the furnace to the press. This can be done, for example, by appropriate mechanisms.

To increase the productivity of several ovens can be used in parallel, which feed a common press. It is exploited that the heating process in the oven usually requires significantly more time than the downstream pressing process.

Preferably, the transport device from a loading station in the direction of movement in front of the furnace at least until a pressing position in the press continuously. This is a relatively simple design to guide the components tamper-free not only in the oven, but also from the oven in the press.

In a preferred embodiment, the press is designed as a press with a horizontal pressing direction. Turning or pivoting of the components, which are usually performed in a vertical orientation through the furnace is then not required. Accordingly, low cycle times can be realized.

The transport device can be guided outside the furnace and / or the press. Thus, the temperature load of the transport device is kept low. The guided on the transport device means are then passed through a breakthrough of the furnace, so that the components are completely heated in the oven. The breakthrough runs in the transport direction or in the furnace longitudinal direction and is in particular formed in a floor or a ceiling of the furnace.

In an alternative embodiment it is provided that the transport device is guided within the furnace and / or the press. The oven can then be gas-tight and operated under a protective gas atmosphere.

In a preferred embodiment, the means for transporting the components each have at least one receiving element, to which one of the components can be attached in a suspended manner. The receiving element may be formed in the simplest case as a hook or eye and cooperate with a corresponding eyelet or a corresponding hook of the component. But it is also an active embodiment of the receiving element possible, which is designed for example as a gripper. In order to realize a plurality of coupling points between the means and the component, a plurality of receiving elements may be provided on a means or provide each receiving element a plurality of coupling points available. This allows a stable transport of the components. In any case, a contact of the receiving element or elements of the means takes place in an area with the component, which lies outside of a utilization area. A hanging arrangement of the components on the means has the advantage that the components are guided in a stable position. In particular, a drop or buckling of the components is then hardly to be feared.

An alternative embodiment provides that the means for transporting the components each have at least one receiving element, to which one of the components can be fastened upright. The receiving element or the receiving elements may in turn be designed as hooks, eyes, grippers or the like, wherein one or more receiving elements are assigned to a means to provide one or more coupling points. Depending on the shape of the components, a stationary transport may be cheaper than a hanging one. Especially with heavy components, a lighter absorption of weight forces can be done.

Preferably, the means for transporting the components cover means, with which the components are at least partially covered. Each agent can each have a cover. With these cover devices, it is possible to temper individual areas of the components differently. By covering a region of the components by means of a covering device, this area in the furnace is usually subjected to less heat and thus less heated. This can be used to achieve areas of different ductility or with different degrees of hardness.

In a preferred development it is provided that a tempering device is arranged in the furnace and / or between the furnace and the press and / or in the press, with the individual regions of the components are actively tempered. The tempering device can, for example, have infrared radiators in order to additionally heat individual areas of the components. It is also possible to specifically cool individual areas of the components, so that they are pressed at a lower temperature. In any case, an active temperature control of individual areas or at least a single area of a component, which can be used to adjust the strength.

Advantageously, the transport device is designed as a guide rail, in which the means for transporting the components are guided. This is a relatively simple embodiment to transport the funds out. In this case, a central drive for all means may be provided, but it is also conceivable to provide the means with their own drives.

1. a) Befestigen der Bauteile an Mitteln zum Transportieren der Bauteile, welche in einer Transportvorrichtung verschiebbar gelagert sind und Transport der Bauteile entlang der Transportvorrichtung zu einem Ofen,
2. b) Einbringen der an den Mitteln zum Transportieren der Bauteile befestigten Bauteile in den Ofen,
3. c) Transport der an den Mitteln zum Transportieren der Bauteile befestigten Bauteile durch den Ofen entlang der Transportvorrichtung, wobei die Bauteile erwärmt werden,
4. d) Fortlaufender Transport der an den Mitteln zum Transportieren der Bauteile befestigten Bauteile entlang der Transportvorrichtung zu einer Presse und
5. e) Formgebung der Bauteile in der Presse.

The above-mentioned object is achieved in a method for pressing components using a device according to one of claims 1 to 11 according to the invention in that the following steps are provided:

1. a) securing the components to means for transporting the components which are displaceably mounted in a transport device and transporting the components along the transport device to a furnace,
2. b) introducing the components attached to the means for transporting the components into the furnace,
3. c) transporting the components attached to the means for transporting the components through the furnace along the transport device, wherein the components are heated,
4. d) Continuous transport of the components attached to the means for transporting the components along the transport device to a press and
5. e) Shaping the components in the press.

The components are therefore not introduced with different manipulators first in the oven and then in the press. Rather, there is a continuous transport of the components with a continuous transport device, which is at least from a loading station in the direction of movement in front of the furnace to a pressing position in the press continuously. The components can be contacted only in areas of the means that are outside of a later range of use. A coating applied there can thus neither damage the means, nor can be effected by the means an impairment of the coating.

Overall, not only a shorter cycle time is obtained, but also increases the variability, especially in terms of usable coatings.

Figur 1

einen Längsschnitt einer erfindungsgemäßen Vorrichtung,

Figur 2

einen Durchlaufofen im Querschnitt und

Figur 3

eine Weiterbildung der Vorrichtung nach Figur 1.

The invention will be described in more detail below with reference to preferred embodiments in conjunction with the drawings. Hierin show in a schematic view:

FIG. 1

a longitudinal section of a device according to the invention,

FIG. 2

a continuous furnace in cross section and

FIG. 3

a development of the device according to FIG. 1 ,

In FIG. 1 a device 1 for press hardening of components 2 is shown in longitudinal section. The device 1 has an oven 3, which is designed as a continuous furnace. Above the furnace 3 runs a transport device 4, which has means 5, on which the components 2 can be attached via receiving elements 6 hanging.

With the help of the transport device 4, the components 2 of a loading station 7, in which the means 5 are loaded with the components, through the oven 3 through to a pressing position in a press 8 can be transported without a further manipulation is required in between. The furnace 3 has for this purpose an entrance door 9 and on the exit side an exit door 10, which are each designed as sliding doors. About the front door 9 and the exit door 10, the oven 3 can be closed or opened to achieve a better heat distribution in the closed state and in particular to keep the heat losses low.

The transport device 4 is formed as a kind of guide rail, in which the means 5 are guided. In the area of the loading station 7, a first drive mechanism 11 is provided, which causes a slowed movement of the means 5 and thus simplifies the loading. In the region of an exit of the furnace 3, the transport device 4 is assigned a second drive mechanism 12, which serves as an emergency discharge and bridges the distance to the press. The means 5 with the components 2 heated in the oven are thereby moved at a higher speed from the outlet of the furnace into the press 8. The time in which the components cool down 2 is thus kept low.

The components 2 thus come with very little loss of temperature in the press 8 and can be converted directly there.

The press 8 is formed in this embodiment as a horizontal press, so has a horizontal pressing direction, so that the hanging or vertically aligned components 2 can be pressed directly without having to be rotated or pivoted before. Rather, the components 2 can be easily brought to the means 5 hanging tamper-free in the press.

The receiving elements 6 of the means 5 contact the components 2 in connection regions 13, which lie outside a use region 14 of the components 2. In particular, the connection regions 13, as shown in the exemplary embodiments, are formed in the shape of tabs on the use region 14. As a result, a coating which is present in the use region 14 does not come into contact with the receiving elements 6 of the means 5, so that more aggressive coatings which lead to corrosion on the means 5 or on the receiving elements 6 could be easily handled by the connection areas 13 can be carried out uncoated.

The use of contact-sensitive coatings is possible without any problems, since no contact with the means 5 takes place in the use region 14. Rather, the use areas 14 are guided without contact through the oven 3 into the press 8.

A release of the components 2 from the means 5, for example, take place during the pressing operation by the terminal portions 13 are separated in the press 8. However, it is also conceivable to move the components 2 out of the press again via the means 5 and only then to separate them from the means 5.

In the illustrated embodiment, the components 2 via two coupling points 15, 16 are held on the receiving elements 6 of the means 5. The coupling points 15, 16 are formed as protruding pins, which engage in eyelets, which are formed in the connection areas 13 of the components 2. The components 2 are thus held in a form-fitting manner by being pushed onto the pins of the coupling points 15, 16. A separate embodiment of the receiving elements 6 but is easily possible. For example, the receiving elements 6 may also be designed as active grippers, so that lower demands are placed on the shape of the connecting regions 13 of the components 2. Optionally, a separate embodiment of the connection regions can also be dispensed with.

In FIG. 2 is a cross section through the furnace 3 and the transport device 4 is shown. The means 5 are movably guided via wheels 17 in the transport device 4 designed as a guide rail. The components 2 are attached via the receiving elements 6 hanging on the means 5 and thus to the transport device 4, so that the components 2 can be passed through the furnace 3 without contact with the use region 14 of the components 2.

In side walls 18, 19 of the furnace 3, gas burners 20 are introduced, for example. By an appropriate number of gas burners 20 an optimal temperature distribution in the oven 3 can be achieved. The gas burners 20 serve, for example, for introducing heat energy into the furnace. In this case, 3 temperatures of up to 1200 ° C can be generated in the oven.

It is also possible to divide the furnace 3 into different temperature zones in order to meet different process requirements.

In FIG. 3 the device 1 is shown with an additional, arranged between the oven 3 and press 8 tempering device 21. In the tempering device 21, an active partial temperature control of the components, ie an active heating or cooling of partial areas can take place. For heating, the tempering device 21 may, for example, infrared radiators to produce a local heating of the components 2 via radiant heat. Cooling can be carried out, for example, with the aid of air nozzles, which are formed in the temperature control device 21.

Alternatively or in addition to an active tempering device 21 can also be provided to provide the means 5 with cover devices to partially cover the components 2 before transport through the furnace 3 and thus allow less heating in these areas. As a result, individual regions of the components 2 can be kept cooler.

Due to the partial temperature differences, a ductility or a degree of hardness or a strength adjustment in individual areas of the finished components can be influenced.

The invention is not limited to the exemplary embodiments shown, but can be modified in many ways. Instead of forming the furnace as a hanging furnace, that is, with a transport device arranged above the furnace, at which the components are suspended, a design as a holding furnace is also conceivable in which the components are transported standing on the means. The components, which are shown in the embodiment as simple sheets, may also have more complicated shapes and be formed, for example, as profiles or tubes or by a combination of several elements, which are welded together, for example.

By means of the device according to the invention, coated components, in particular coated metal sheets, can be heat-treated and deformed, optionally with simultaneous controlled cooling, without the transport device being thermochemically stressed by the coating or damage to the coating due to contact with the transport device being feared. By dispensing with additional manipulators by the Transport device, the components transported continuously from a loading station through the oven to the press, cycle times, especially the time from the exit from the oven until the beginning of the pressing process, significantly reduced. The components are thus introduced by the same means in the oven, passed through the oven and transported in the press.

All of the claims, the description and the drawings resulting features and advantages, including design details, spatial arrangements and method steps may be essential to the invention both in itself and in various combinations.

Claims (12)

1. Apparatus for the press-hardening of components (2), having at least one furnace (3), a press (8) arranged downstream of the at least one furnace (3), and a transport apparatus (4), wherein means (5) for transportation of the components (2) are moveably mounted in the transport apparatus (4), characterised in that the means (5) are moveable with the components (2) along the transport apparatus (4), through the furnace (3) and into the press (8), wherein the transport apparatus (4) is continuous between the furnace (3) and the press (8), and wherein transport of the components (2) from the furnace (3) to the press (8) can be carried out without manipulation.
2. Apparatus according to claim 1, characterised in that the transport apparatus (4) is continuous from a loading station (7) located, in the movement direction, before the furnace (3) at least as far as a pressing position in the press (8).
3. Apparatus according to claim 1 or 2, characterised in that the furnace (3) is formed as a continuous furnace.
4. Apparatus according to any of the preceding claims, characterised in that the press (8) is formed as a press with a horizontal pressing direction.
5. Apparatus according to any of the preceding claims, characterised in that the transport apparatus (4) is guided externally to the furnace (3) and/or the press (8).
6. Apparatus according to any of the preceding claims, characterised in that the transport apparatus (4) is guided within the furnace (3) and/or the press (8).
7. Apparatus according to any of the preceding claims, characterised in that the means (5) for transportation of the components (2) have receiving elements (6), on which the components (2) can be fastened in a suspended state.
8. Apparatus according to any of claims 1 to 6, characterised in that the means (5) for transportation of the components (2) have receiving elements (6), on which the components (2) can be fastened in a standing state.
9. Apparatus according to any of the preceding claims, characterised in that the means (5) for transportation of the components (2) are provided with cover devices, with which the components (2) can be at least partially covered.
10. Apparatus according to any of the preceding claims, characterised in that a tempering apparatus (21) is arranged in the furnace (3) and/or between the furnace (3) and the press (8) and/or in the press (8), with which individual regions of the components (2) can be actively tempered.
11. Apparatus according to any of the preceding claims, characterised in that the transport apparatus (4) is formed as a guide rail, in which the means (5) for transportation of the components (2) are guided.
12. Method for the press-hardening of components using an apparatus according to any of claims 1 to 11, comprising the following steps:

    a) fastening the components (2) on means (5) for transportation of the components (2), which are mounted in a displaceable manner in a transport apparatus (4), and transport of the components (2) along the transport apparatus (4) to a furnace (3),

    b) introducing the components (2) fastened on the means (5) for transportation of the components into the furnace (3),

    c) transporting the components (2) fastened on the means (5) for transportation of the components through the furnace (3) along the transport apparatus (4), wherein the components (2) are heated,

    d) further transporting the components (2) fastened on the means (5) for transportation of the components along the transport apparatus (4) to a press (8),

    e) forming of the components (2) in the press (8).

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