Method for retrofitting a thermal treatment installation

Abstract

The invention relates to a method for retrofitting a heat treatment installation, having at least the following steps: a) dividing a continuous furnace (2) into a first furnace (3) and a second furnace (4), b) providing a temperature control station (5) in the heat treatment installation (1), wherein the temperature control station (5) is provided downstream of the first furnace (3) and upstream of the second furnace (4), and the temperature control station (5) is additionally provided and designed for setting a temperature difference between at least a first subregion and at least a second subregion of a metal component (6) to be treated, and c) adapting the operating mode of the heat treatment installation (1). The invention can be used in particular for retrofitting an existing press quench production line in which a press quench tool is arranged downstream of a continuous furnace, in particular a roller furnace. Preferably, the retrofitted heat treatment production line can perform a partial heat treatment of the metal component if required.

Description

[0001] This invention relates to a method for retrofitting heat treatment equipment. The invention is particularly applicable to retrofitting existing press quenching production lines where the press quenching tools are arranged downstream of a continuous furnace, especially a roller furnace. The advantage of the retrofitted heat treatment production line is that it allows for partial heat treatment of metal components when needed.

[0002] To manufacture safety-related body components made of sheet steel, it is typically necessary to harden the steel sheets during or after the formation of body components. For this purpose, a heat treatment method known as "press quenching" has been developed. In this process, the steel sheet, usually supplied in sheet form, is first heated in a furnace and then cooled while being formed in a press, thereby hardening it.

[0003] For many years, efforts have been made to produce vehicle body components, such as A-pillars and B-pillars, side impact protection components in doors, floor panels, frame components, bumpers, crossbeams of the floor and roof, and front and rear side beams, using a press-quenching process. These components have different strengths in sub-regions, allowing them to perform different functions in different parts. For example, the central region of the B-pillar should have high strength to protect occupants in the event of a side impact. Meanwhile, the upper and lower regions of the B-pillar should have relatively lower strength to absorb deformation energy during a side impact and facilitate connection with other body components during assembly.

[0004] To form such partially hardened body components, the hardened components must have different strength properties in their sub-regions. For this purpose, for example, in new equipment, one or more temperature control stations can be placed between the furnace and the press-quenching tool. In this case, the temperature control station is set and designed to set different temperatures in the sub-regions of the component (which are initially heated uniformly), thereby producing different strength properties in the sub-regions during the subsequent press-quenching process. Optimal cycle times can be achieved in this configuration, which plays a particularly important role in the automotive industry, especially if the furnace, temperature control station, and press-quenching tool components are arranged "in a straight line," i.e., directly and continuously.

[0005] If existing equipment is to be retrofitted with a temperature control station, it is often observed that there is insufficient space for a "tandem" arrangement, so the temperature control station is placed elsewhere; for example, it must be placed laterally offset relative to the furnace and / or quenching tools (viewed from the production volume direction). With such an arrangement, optimal cycle times can only be achieved under difficult conditions, or are simply impossible to achieve.

[0006] Even with modifications, and the necessary space for a “straight-line” arrangement, problems arise because conventional pressure quenching methods (optionally) can still generally be performed on the modified equipment. However, the issue here is that the arrangement of the temperature control station (which is normally shut down during operation) between the furnace outlet and the pressure quenching tool causes a transfer delay from the furnace to the pressure quenching tool, potentially leading to unwanted intense cooling before it enters the tool.

[0007] Based on this, the object of the present invention is to at least partially solve the problems described in the prior art. In particular, a method for modifying heat treatment equipment is provided, which allows for different heat treatments of metal components in parts as efficiently as possible on an industrial scale, and in particular, allows for conventional pressure quenching methods to be performed as efficiently as possible.

[0008] These objectives are achieved through the features of the independent claims. Further advantageous embodiments of the solution proposed herein are specifically described in the dependent claims. It should be noted that the features listed separately in the dependent claims can be combined with each other in any technically meaningful manner and define further embodiments of the invention. Furthermore, the features specified in the claims are described and explained in more detail in the specification, thereby demonstrating further preferred embodiments of the invention.

[0009] The method for modifying heat treatment equipment according to the present invention comprises at least the following steps:

[0010] a) Divide the continuous furnace into the first furnace and the second furnace.

[0011] b) A temperature control station is provided in the heat treatment equipment, wherein the temperature control station is located downstream of the first furnace and upstream of the second furnace, and wherein the temperature control station is further configured and designed to set the temperature difference between at least a first sub-region and at least a second sub-region of the metal assembly to be treated, and

[0012] c) Adjust the operating mode of the heat treatment equipment.

[0013] Performing the method in the conventional manner produces the method steps shown in sequence a), b), and c). Individual or multiple of the method steps can be performed simultaneously, sequentially, and / or at least partially in parallel.

[0014] The proposed method is preferably used to retrofit heat treatment equipment or heat treatment production lines with continuous furnaces and quenching tools. The quenching tools are positioned downstream of the (to be retrofitted) continuous furnace. Specifically, the quenching tools are configured and designed to simultaneously or at least partially in parallel form and (at least partially) quench the components. The continuous furnace may be a roller furnace. Preferably, the heat treatment equipment to be retrofitted and / or the retrofitted heat treatment equipment are arranged in a straight line. The continuous furnace and quenching tools of the heat treatment equipment to be retrofitted, i.e., the first furnace, the temperature control station, the second furnace, and the quenching tools (in the stated order), are preferably arranged directly in sequence.

[0015] The metal component (to be processed by heat treatment equipment) is preferably a metal sheet, steel sheet, or at least partially pre-formed semi-finished product. Preferably, the metal component is made of (hardenable) steel, such as boron (manganese) steel, like 22MnB5 steel. More preferably, the metal component is at least substantially provided with or pre-coated with a (metallic) coating. The metallic coating may be, for example, a (primarily) zinc-containing coating or a (primarily) aluminum-containing and / or silicon-containing coating, particularly a so-called aluminum / silicon (Al / Si) coating.

[0016] In step a), the (existing) continuous furnace, particularly a roller furnace, is divided into a first furnace and a second furnace. Preferably, the division is carried out in such a way that the first furnace and the second furnace each form a continuous furnace, particularly a roller furnace. Alternatively, the division can be carried out in such a way that the first furnace forms a continuous furnace and the second furnace forms a chamber furnace. The division can be carried out by mechanical and / or thermal splitting.

[0017] According to an advantageous embodiment, it is recommended to remove the area of ​​the continuous furnace in step a). This is specifically achieved in such a way that free space is created (in the continuous furnace) for the temperature control station.

[0018] In step b), a temperature control station is provided in the heat treatment equipment, wherein the temperature control station is (directly) located downstream of the first furnace and (directly) located upstream of the second furnace. The temperature control station is configured and designed to set a temperature difference between at least a first sub-region and at least a second sub-region of the metal component to be treated (by the heat treatment equipment). For this purpose, the temperature control station may have one or more nozzles configured and designed to discharge (cooling) fluid into the at least first sub-region of the component.

[0019] According to an advantageous embodiment, it is recommended that the temperature control station in step b) be located between the first furnace and the second furnace. Preferably, the temperature control station is arranged such that the first furnace, the temperature control station, and the second furnace (in the stated order) are arranged in a particularly direct and continuous manner. "Direct and continuous" means that, in this case, no other components for heat treatment are arranged between the temperature control station and the respective furnace. However, a minimum distance of 0.5 m can be provided between the temperature control station and the first furnace and / or the second furnace. In other words, preferably, in step b), the temperature control station is arranged in a straight line with the first furnace and the second furnace.

[0020] In step c), the operating mode of the heat treatment equipment is adjusted. If multiple operating modes are provided in the heat treatment equipment to be modified, one or more, or even all, of the operating modes of the heat treatment equipment may be adjusted or changed in step c).

[0021] According to an advantageous embodiment, it is recommended that in step c), the operating mode of the heat treatment equipment be adjusted so that the production rate of the first furnace is reduced compared to the production rate of the continuous furnace, especially if partial heat treatment, particularly quenching, is performed by the (modified) heat treatment equipment or the (modified) heat treatment equipment is operated in a first operating mode, wherein the temperature difference between a first sub-region and a second sub-region of at least one metal component is set in the component by the temperature control station. Preferably, the production rate of the first furnace is reduced to a speed in the range of 0.01 to 1 m / s, particularly a speed in the range of 0.08 to 0.3 m / s.

[0022] Preferably, the reduced production speed, when using (modified) heat treatment equipment for partial heat treatment, increases the cycle time that can be completed; however, if only a relatively small number of components are to be partially heat treated, it would be a very sensible solution if the process could be carried out "in a straight line".

[0023] According to another advantageous embodiment, it is recommended that in step c), the operating mode of the heat treatment equipment be adjusted such that the furnace temperature in the second furnace is higher than the (maximum or highest) furnace temperature of the (to be modified) continuous furnace, specifically, if no partial heat treatment is performed by the (modified) heat treatment equipment, or if the (modified) heat treatment equipment is operating in a second operating mode in which no temperature difference is established between the first and second sub-regions of the component. Preferably, the furnace temperature in the second furnace is increased by at least 10K, or even at least 20K, compared to the (maximum) furnace temperature of the (to be modified) continuous furnace.

[0024] Increasing the furnace temperature in the second furnace has a particular advantage: it allows the (modified) heat treatment equipment to continue the conventional press quenching process with minimal cycle time loss. Due to the temperature control station, a significant amount of usable furnace length is often lost. To compensate for this, increasing the temperature in the second furnace is a preferred method. In this way, the desired final temperature can still be achieved despite reducing the furnace length. Furthermore, increasing the temperature in the second furnace (only) has the advantage that, in the event of a shutdown, components in the elevated furnace may reach excessively high temperatures; only those components located in the second furnace must be discarded, thus limiting the damage. If the temperatures in both the first and second furnaces increase due to the overall reduction in furnace length, the entire furnace charge must be discarded. In addition to material loss, the downtime during the furnace "emptying" process must also be considered.

[0025] Optionally, in step c), the operating mode of the heat treatment equipment is preferably adjusted so that the furnace temperature in the second furnace is lower than or just equal to the (maximum) furnace temperature of the (to be modified) continuous furnace.

[0026] Preferably, it is assumed that if, in the (adjusted) operating mode, in the event of an (intentional) interruption, the end of the cycle is selected with the second furnace empty. Then, if necessary, no components need to be discarded. Particularly preferably, temperature measurement data from, for example, a pyrometer located downstream of the first furnace and / or the second furnace is used to determine the end of the cycle.

[0027] It is useful to establish a non-uniform temperature distribution or different temperature zones along the relevant furnace length in the first furnace and / or the second furnace, each of which can be designed as a continuous furnace. Preferably, different temperature zones are set in the first furnace (in the production direction), while a substantially uniform furnace temperature is set in the second furnace.

[0028] A method for operating a heat treatment apparatus modified according to the method proposed herein is also proposed, wherein, in a first operating mode of the heat treatment apparatus, a temperature difference between a first sub-region and a second sub-region of at least one metal component is set by the temperature control station in the assembly, and wherein, in a second operating mode of the heat treatment apparatus, there is no (intentionally or deliberately set) temperature difference between a first sub-region and a second sub-region of at least another metal component in the assembly by the temperature control station.

[0029] Typically, the temperature control station is equipped with component-specific inserts that allow for different temperature control of first and second regions of components with different strengths within the component. If the component to be produced does not have different first and second regions, but rather has approximately uniform strength throughout the component, a channel element can be used instead of a unit, which insulates the component from the surrounding environment. This reduces heat radiation from the component and thus reduces temperature loss of the component during its journey from the first furnace to the second furnace. Preferably, an additional heating device can be provided to maintain the interior of the channel element at an elevated temperature to significantly reduce heat loss due to the small temperature difference compared to the surrounding environment. Particularly preferably, the channel element can be heated such that its internal temperature approximately corresponds to the internal temperature of the first or second furnace. Therefore, temperature drops within the component can be largely avoided.

[0030] Optionally, it is recommended to set the internal temperature of the channel element slightly higher than the temperature in the first furnace to further shorten the cycle time. Similar to the potential temperature rise in the second furnace, appropriate component tracking in the controller should be used to monitor whether, in this case, the maximum permissible residence time of the components in the channel element is exceeded, which could lead to a temperature rise that the components themselves do not allow. According to this method, compared to the original equipment, it is not necessary to increase the production time of components in the first and second regions that do not require different temperature control. If necessary, the total production time can also be reduced compared to the original equipment by increasing the internal temperature of the channel element and / or the second furnace.

[0031] According to an advantageous embodiment, it is recommended that at least the following steps be performed during the first operating mode:

[0032] a1) Heating the (entire) component in the first furnace, particularly by radiant heat and / or convection, preferably at least 500 K [Kelvin], especially preferably at least 650 K or even at least 750 K.

[0033] b1) Move the component into the temperature control station.

[0034] c1) Cooling, particularly convective cooling, of at least a first sub-region of the components in the temperature control station, wherein the temperature difference between the at least first sub-region and the at least second sub-region of the components is preferably set to at least 50K or even at least 100K.

[0035] d1) Moving the component from the temperature control station to the second furnace, and

[0036] e1) In the second furnace, at least a first sub-region of the component is heated, preferably at least 100K, particularly at least 150K or even at least 200K, in particular by means of radiant heat and / or convection.

[0037] According to another advantageous embodiment, it is recommended (in step a1) that the component moves through the first furnace at a speed in the range of 0.01 to 1 m / s. Preferably, the component moves through the first furnace at a speed in the range of 0.08 to 0.3 m / s.

[0038] According to another advantageous embodiment, it is recommended that at least the following steps be performed during the second operating mode:

[0039] a2) Heating the components in the first furnace, particularly by radiant heat and / or convection, and

[0040] e2) Heating the component in the second furnace, particularly by radiant heat and / or convection. According to yet another advantageous embodiment, it is recommended that at least the following steps be performed between steps a2 and e2:

[0041] b2) Move the component into the temperature control station.

[0042] c2) Reduce the cooling rate of the component or heat the component in the temperature control station, particularly by means of radiant heat, and

[0043] d2) Move the component from the temperature control station to the second furnace.

[0044] The details, features, and advantageous embodiments discussed in connection with the method presented at the outset can also be derived from the method presented herein, and vice versa. In this regard, reference is made entirely to the statements herein for better characterization of the features.

[0045] The invention and technical environment will be explained in more detail with reference to the accompanying drawings. It should be noted that the invention should not be limited to the embodiments shown. In particular, unless explicitly stated otherwise, aspects may be extracted from the facts explained in the drawings and combined with other components and / or insights from other drawings and / or this specification. In the drawings, the following are schematically shown:

[0046] Figure 1: Shows known heat treatment equipment that can be modified using the method proposed in this paper, and

[0047] Figure 2 Figure 1 shows a heat treatment apparatus modified using the method proposed herein.

[0048] Figure 1 schematically illustrates a known heat treatment apparatus 1 that can be modified using the method proposed herein. The heat treatment apparatus 1 has a quenching tool 7, which is (directly) arranged downstream of a continuous furnace 2. Therefore, the heat treatment apparatus 1 here represents a quenching production line.

[0049] Figure 2 A heat treatment apparatus 1 according to Figure 1 is shown, which has been modified using the method proposed herein. For this purpose, the continuous furnace is divided into a first furnace 3 and a second furnace 4. A temperature control station 5 is then installed in the heat treatment apparatus 1, wherein the temperature control station 5 is (directly) located downstream of the first furnace 3 and upstream of the second furnace 4. The temperature control station 5 is configured and designed to set the temperature difference between at least a first sub-region and at least a second sub-region of the metal component 6 to be treated.

[0050] Therefore, a method for modifying heat treatment equipment is provided, which at least partially solves the problems outlined with reference to the prior art. In particular, the method allows for the modification of heat treatment equipment that enables different heat treatments of metal components in parts to be performed as efficiently as possible on an industrial scale, and especially enables conventional press quenching methods to be performed as efficiently as possible.

[0051] Reference Symbol List

[0052] 1. Heat treatment equipment

[0053] 2 continuous furnaces

[0054] 3 First Furnace

[0055] 4. Second furnace

[0056] 5 Temperature control stations

[0057] 6 components

[0058] 7. Press Quenching Tools

Claims

1. A method for modifying heat treatment equipment (1), characterized in that, It has at least the following steps: a) Divide the continuous furnace (2) into the first furnace (3) and the second furnace (4). b) A temperature control station (5) is provided in the heat treatment equipment (1), wherein the temperature control station (5) is located downstream of the first furnace (3) and upstream of the second furnace (4), and wherein the temperature control station (5) is additionally provided and designed to set the temperature difference between at least a first sub-region and at least a second sub-region of the component (6) of the metal to be treated, and c) Adjust the operating mode of the heat treatment equipment (1) so that the furnace temperature in the second furnace (4) is higher than the furnace temperature in the continuous furnace (2).

2. The method according to claim 1, characterized in that, In step a), the area of ​​the continuous furnace (2) is removed.

3. The method according to claim 1, characterized in that, In step b), the temperature control station (5) is located between the first furnace (3) and the second furnace (4).

4. The method according to any one of the preceding claims, characterized in that, In step c), the operating mode of the heat treatment equipment (1) is adjusted so that the production speed through the first furnace (3) is lower than the production speed through the continuous furnace (2).

5. A method for operating the heat treatment equipment (1) modified according to any one of the preceding claims, characterized in that, In the first operating mode of the heat treatment equipment (1), the temperature control station (5) sets a temperature difference between the first sub-region and the second sub-region of the component (6) of at least one metal, and wherein, in the second operating mode of the heat treatment equipment (1), the temperature control station (5) sets no temperature difference between the first sub-region and the second sub-region of the component (6) of at least one other metal.

6. The method according to claim 5, characterized in that, At least the following steps shall be performed during the first operating mode: a1) Heating the component (6) in the first furnace (3). b1) Move the component (6) into the temperature control station (5), c1) Cooling at least a first sub-region of the component (6) in the temperature control station (5), wherein a temperature difference is provided between at least a first sub-region and at least a second sub-region of the component (6). d1) Moving the component (6) from the temperature control station (5) into the second furnace (4), and e1) Heating at least the first sub-region of the component (6) in the second furnace (4).

7. The method according to claim 6, characterized in that, The component (6) moves through the first furnace (3) at a speed of 0.01 m / s to 1 m / s.

8. The method according to any one of claims 5 to 7, characterized in that, Perform at least the following steps during the second operating mode: a2) Heating the component (6) in the first furnace (3), and e2) The component (6) is heated in the second furnace (4).

9. The method according to claim 8, characterized in that, At least the following steps should be performed between steps a2 and e2: b2) Move the component (6) into the temperature control station (5). c2) In the temperature control station (5), reduce the cooling rate of the component (6) or heat the component (6), and d2) Move the component (6) from the temperature control station (5) into the second furnace (4).

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