阅读说明：本技术 钢板构件的制造方法 (Method for manufacturing steel plate member ) 是由 扬科·巴尼克 德克·罗森斯托克 于 2019-01-08 设计创作，主要内容包括：本发明涉及一种用于制造钢板构件(1)的方法,该方法包括步骤：-钢板构件(1)的加热,其中在钢板构件(1)的第一区域中进行第一温度控制,使得在第一区域中实现完全奥氏体化,并且在钢板构件(1)的第二区域(3)中进行第二温度控制,使得在第二区域(3)中实现部分奥氏体化,-钢板构件的(1)的第一部分修整和成型,其中,第一部分修整沿着预定切割轮廓的第一部分长度(2)进行,并且第一部分长度(2)在钢板构件(1)的第一区域中延伸,-钢板构件(1)的冷却,-钢板构件(1)的第二部分修整,其中,第二部分修整沿着预定切割轮廓的第二部分长度(4)进行,并且第二部分长度(4)在钢板构件的第二区域(3)中延伸。本发明还涉及另一种方法,其中,通过加热实现了钢板构件(1)的完全奥氏体化,并且通过在成型和第一部分修整之后进行并且在第二部分修整之前进行冷却,在第一区域中实现了奥氏体向马氏体和/或贝氏体的至少部分转变,而在第二区域中实现了没有或部分奥氏体向马氏体和/或贝氏体的转变。(The invention relates to a method for producing a steel sheet component (1), comprising the steps of: -heating of the steel sheet component (1), wherein a first temperature control is performed in a first region of the steel sheet component (1) such that complete austenitization is achieved in the first region, and a second temperature control is performed in a second region (3) of the steel sheet member (1), so that a partial austenitization is achieved in the second region (3), trimming and shaping a first portion of the steel sheet component (1), wherein the first partial trimming is carried out along a first partial length (2) of the predetermined cutting contour, and the first partial length (2) extends in a first region of the steel sheet component (1), cooling of the steel sheet component (1), second partial trimming of the steel sheet component (1), wherein the second partial trimming is carried out along a second partial length (4) of the predetermined cutting contour, and the second partial length (4) extends in a second region (3) of the steel sheet component. The invention also relates to a further method, wherein a complete austenitization of the steel sheet component (1) is achieved by heating, and by cooling after forming and first partial trimming and before second partial trimming, an at least partial transformation of austenite into martensite and/or bainite is achieved in the first region, while no or partial transformation of austenite into martensite and/or bainite is achieved in the second region.)

1. Method for manufacturing a steel sheet component (1), characterized by the steps of:

-heating of the steel sheet component (1), wherein a first temperature control is carried out in a first region of the steel sheet component (1) such that complete austenitization is achieved in the first region, and a second temperature control is carried out in a second region (3) of the steel sheet component (1) such that no or partial austenitization is carried out in the second region (3),

-shaping and first partial trimming of the steel plate component (1), wherein the first partial trimming is performed along a first partial length (2) of the predetermined cutting profile and the first partial length (2) extends in a first region of the steel plate component (1),

-cooling of the steel sheet member (1),

-second partial trimming of the steel plate member (1), wherein the second partial trimming is performed along a second partial length (4) of the predetermined cutting profile, and the second partial length (4) extends in a second area (3) of the steel plate member.

2. Method for manufacturing a steel sheet component (1), characterized by the steps of:

-heating of the steel sheet component (1), wherein a third temperature control of the steel sheet component (1) as a whole is carried out in such a way that a complete austenitization is achieved,

-shaping and first partial trimming of the steel plate member (1), wherein the first partial trimming is performed along a first partial length (2) of the predetermined cutting profile and the first partial length (2) extends in a first region of the steel plate member,

-cooling of the steel sheet component (1), wherein in a first region of the steel sheet component a fourth temperature control is performed such that in the first region austenite is at least partially converted into martensite and/or bainite, and in a second region (3) of the steel sheet component a fifth temperature control is performed such that in the second region (3) no or partially austenite-to-martensite and/or bainite transformation takes place,

-second partial trimming of the steel plate member (1), wherein the second partial trimming is performed along a second partial length (4) of the predetermined cutting profile, and the second partial length (4) extends in a second area (3) of the steel plate member (1).

3. The method of claim 1 or 2, wherein the forming and the first portion trimming are performed substantially simultaneously.

4. Method according to any of the preceding claims, wherein the steel plate component (1) is straightened and/or calibrated during and/or after the second partial trimming.

5. A method according to any of the preceding claims, wherein shaping, first partial trimming and cooling are performed in a first tool, and second partial trimming is performed in a second tool.

6. Method according to any one of the preceding claims, wherein the trimmed remainder is removed from the steel plate member (1) after the second portion trimming.

7. Method according to any of the preceding claims, wherein a coating or cladding is applied onto the steel sheet member (1) before heating, and the heating of the steel sheet member (1) comprises a first stage in which a sixth temperature control of the steel sheet member (1) is performed such that a partial or complete alloying of the coating or cladding is achieved.

8. A method according to claim 7, wherein the coating consists of a zinc compound or an aluminium compound, in particular an aluminium silicon coating.

9. Method according to any one of the preceding claims, wherein the steel sheet member (1) is used as a structural member in a vehicle, in particular as a pillar, a longitudinal beam, a sill, a pillar, a tunnel, or as a chassis member, in particular as a suspension arm, a composite steering axle.

Technical Field

The present invention relates to a method for manufacturing a steel plate member.

Background

Methods for hot forming and finishing components made of sheet steel are known from the prior art. Here, due to the high cost, especially the refurbishment of components is one of the main challenges in processing. Dressing in the cold state (hard dressing) can lead to high wear of the cutting tool and may lead to edge cracking of the component. In contrast, if the sheet material is trimmed directly in the forming tool in the hot state during the press hardening process, the wear of the tool can be reduced, but more complicated structures, for example for removing scrap, need to be implemented in the manufacturing equipment. In addition, there are problems in that it is practically impossible to remove the separated residual material from the integrated tool, and the member is warped during the thermal finishing.

For these reasons, laser cutting has become a preferred cutting technique. This method is limited by the cutting speed since the laser beam moves over the entire cutting edge and is therefore very costly also due to the high investment costs of the laser trimming system. Here, the components are also subject to warping and special safety requirements must also be met when using lasers in manufacture. The economics of press hardening therefore depend on the possibility of replacing laser cutting or abandoning laser cutting.

For example, DE 102016103668B 3 describes a method for finishing components, in which the cutting length is divided into two regions, the larger region being cut in the hot state, while the remaining finishing is carried out in a separate tool with cold finishing. In this way, cold-finishing, which causes high tool wear, is applied only for a part of the total cutting length. However, there is still the disadvantage of cold finishing, in particular increased wear of the cutting tools. In addition, due to trimming in a hard state, cracks may be formed starting from the edges of the member, resulting in damage to the member.

Disclosure of Invention

Against this background, it is an object of the present invention to provide a method in which low wear finishing can be integrated into a thermoforming process.

This object is achieved by a method for manufacturing a steel sheet component, characterized by the steps of:

heating of the steel sheet component, wherein a first temperature control is carried out in a first region of the steel sheet component such that complete austenitization is achieved in the first region and a second temperature control is carried out in a second region of the steel sheet component such that no or partial austenitization is carried out in the second region,

-shaping of the sheet steel member and first partial trimming, wherein the first partial trimming is performed along a first partial length of the predetermined cutting profile and the first partial length extends in a first region of the sheet steel member,

-cooling of the steel sheet component,

-a second partial trimming of the steel plate member, wherein the second partial trimming is performed along a second partial length of the predetermined cutting profile, and the second partial length extends in a second region of the steel plate member.

According to the invention, the first partial trimming, also referred to as thermal trimming in the following, is carried out in a heated state. Due to the elevated temperature, the heated member has a lower shear strength, so that wear of the cutting tool can be advantageously reduced. The separating surface formed during cutting usually consists of relatively smooth regions, in which the material is cleanly separated by the shearing movement, and fracture regions, in which the already partially divided material yields in the form of a fracture under shear stress. The (partial) finishing on the heated component advantageously results in less pronounced fracture areas and correspondingly smoother parting surfaces. Furthermore, the material surrounding the cutting edge is also deformed to a lesser extent during hot trimming. The choice of temperature at which the first partial trimming is carried out preferably depends on the hardness or the temperature dependence of the material texture. It may be a criterion here that the vickers hardness should be below a predetermined value or that the transformation to martensite and/or bainite is accomplished in a certain percentage by austenite.

In the method according to the invention, the shaping of the steel sheet is likewise carried out in the heated state, whereby materials with a higher deformability are advantageously used for this production step as well. For this purpose, the heated steel sheet is transferred into a hot forming tool and brought to the desired shape by closing the tool, thereby generating tensile and compressive stresses. Alternatively, it is also conceivable that both heating and shaping take place in the thermoforming tool.

Preferably, the first partial finishing comprises a major portion of the cutting profile, while the second partial finishing comprises only a minor portion, thereby completing the separation of the steel plate members. Accordingly, the second region of the steel plate member preferably comprises a relatively narrowly confined region, while the first region preferably comprises the remainder of the steel plate member. In order to achieve a lower shear strength of the material and accordingly also a lower wear on the cutting tool for the second partial finishing, the method according to the invention aims to obtain a lower hardness in the second region of the steel sheet component than in the first region by means of heat treatment. According to the invention, this is achieved by heating with local temperature control and subsequent cooling in the first and second regions. The hardness of the heat-treated steel depends to a large extent on the martensite and/or bainite content in the microstructure and is greater than 400 HV. The hardness shown relates to the composite counterpart with a higher hardness, as long as it is a steel composite material. This is in turn given by the amount of austenite produced on heating and the transformation of austenite to martensite and/or bainite that occurs on cooling. In the above method, the hardness of the first region and the second region is mainly affected by temperature control at the time of heating, and is thus affected by austenite formation.

The hardness in the second region is at most 400HV, in particular at most 350HV, preferably at most 300HV, particularly preferably at most 250 HV. HV corresponds to Vickers hardness according to DIN EN ISO 6507-1: 2005 to-4: 2005.

According to the invention, the temperature control, i.e. the selection of the temperatures at which the individual process steps are carried out and the temperature profile of the heating and cooling process as a function of time, is controlled by a time-temperature-austenitization diagram (ZTA diagram) or a time-temperature-transformation diagram (ZTU diagram) of the steel used. With the aid of the ZTU diagram, the expected structure can be estimated from the cooling rate for the cooling process, while the kinetics of austenite formation can be understood on the basis of the ZTA diagram. When applied to the heating step of the method according to the invention, the temperature and duration of the heating process may be adjusted, for example, such that no austenitization or partial or complete austenitization is achieved. Full austenitization is understood to mean that the temperature and heating time are chosen such that austenite formation is completely complete and the steel is present in heterogeneous or homogeneous austenite form according to the ZTA diagram. In contrast, partial austenitization is understood to mean that the process parameters are selected such that the material is transformed only incompletely into austenite and is present, for example, in the form of a mixture of ferrite and austenite. Without austenitizingAustenite is of course absent after the heat treatment. In the ZTA diagram of hypoeutectoid steel, the transformation line Ac_1b(start of austenite formation) and Ac₃(ferrite transformation end) is important. Thus, partial austenitization may be understood as being at the temperature Ac_1bAnd Ac₃With complete austenitization corresponding to a temperature higher than Ac₃The temperature of (2). At Ac_1bHereinafter, austenitization does not occur.

During cooling, the volume fraction or the area fraction of the different tissue structure components, or the hardness of the resulting tissue structure, can be estimated from the ZTU map. In the case of a complete transformation of austenite into martensite and/or bainite, almost all of the austenite portion present after heating is transformed, wherein the martensite and/or bainite is present in particular in an amount of more than 95 area%, preferably more than 97 area%, whereas in the case of a partial transformation, in addition to the formation of martensite and/or bainite, a further structural transformation takes place, so that only a part of the initial austenite portion is transformed into martensite and/or bainite.

In order to achieve different temperature control in the first and second regions, several possibilities are known to the person skilled in the art, which possibilities, together with other methods of achieving different treatments of different regions of the component, fall under the concept of "tailored properties". For example, the heating may be performed in a two-stage process, wherein after the first stage the second region is locally cooled by a fluid or by contact cooling or the like. In this way, in the subsequent second heating phase, a lower temperature is produced in the precooled second region than in the first region, so that austenitization is substantially suppressed. According to the invention, the cooling after the first partial trimming is carried out at a high cooling rate (quenching). As a result, the austenite formed during heating is transformed into martensite and/or bainite substantially without diffusion. Since there is less or even no austenite in the second region after heating, a correspondingly lower amount of or absence of martensite and/or bainite is obtained upon cooling, and thus the desired lower hardness according to the invention. Subsequently, a second partial trimming of the steel plate component is performed along a second partial length of the cutting contour extending in the second area. The second portion trim is advantageously associated with less wear due to the lower hardness of the second region. The second partial finishing, also referred to as cold finishing, is carried out in one or more areas that are more flexible than the rest of the component. Furthermore, edge cracks or microcracks at the edge can be reduced in this way, since there is a lower strength or susceptibility to edge cracks or a higher toughness in these regions.

In one aspect, the lengths of the first and second portions of the predetermined cutting profile are selected so as to separate as large a portion of the cutting profile as possible in the first partial trimming. On the other hand, however, the length and position of the partial cuts should also be such that there is no or only slight warping of the metal sheet, or such warping can easily be compensated for in a further processing step, possibly integrated in the case of second partial trimming. Preferably, the first partial trimming should also not lead to a complete separation of a part of the component, so that the mechanical bond with the rest of the sheet metal component is maintained first. In this way, the steel sheet component can be removed from the tool as a whole without separate remnants remaining therein. Complete separation can then advantageously be carried out in the second partial trimming.

The object mentioned at the outset is further achieved by a method for producing a steel sheet component, characterized by the following steps:

-heating of the steel sheet component, wherein a third temperature control of the steel sheet component as a whole is carried out in such a way that a complete austenitization is achieved,

-shaping and first partial trimming of the steel plate member, wherein the first partial trimming is performed along a first partial length of the predetermined cutting profile and the first partial length extends in a first region of the steel plate member,

cooling of the steel sheet component, wherein in a first region of the steel sheet component a fourth temperature control is carried out such that in the first region austenite is at least partially converted into martensite and/or bainite, and in a second region of the steel sheet component a fifth temperature control is carried out such that in the second region no or partial transformation of austenite into martensite and/or bainite takes place,

-a second partial trimming of the steel plate member, wherein the second partial trimming is performed along a second partial length of the predetermined cutting profile, and the second partial length extends in a second region of the steel plate member.

Also in this method, the thermal finishing is performed in a heated state, thereby obtaining the above-described advantages of the thermal finishing. The different hardness of the first and second regions is, however, influenced here primarily by the temperature control during cooling and thus by the partial transformation of austenite into martensite and/or bainite or by the absence of a corresponding transformation. During heating, both zones are treated in the same way, so that austenitization (temperature controlled at Ac) occurs as completely as possible throughout the component₃Above). Similar to the first method, both the shaping and the first partial trimming are carried out in a heated state, so that the first partial trimming advantageously brings about low wear of the cutting tool and, in addition, a smaller fracture area and a low deformation of the material around the cut. On cooling, the different hardness of the two regions according to the invention is achieved due to the different temperature control of the first region and the second region. The temperature control is in turn controlled by the characteristic curve of the ZTU map, so that the temperature profile can be adjusted according to the desired tissue structure or stiffness associated therewith. The fourth temperature control is selected such that the austenite present is at least partially, in particular completely, transformed into martensite and/or bainite, as a result of which the greatest hardness is achieved in the first region. The fifth temperature control is such that the existing austenite does not transform or only partially transforms into martensite and/or bainite, so that a reduced hardness is obtained in the second region compared to the first region. The forming and cooling are preferably carried out in the same tool, whereby the steel sheet component in the heated state is pressed into a mould and its temperature is reduced during pressing by cooling the forming tool, for example in the form of a water cooling or capillary cooling system. Then, a second partial finishing is carried out in the second region on the completely cooled steel sheet component or in the cold state, so that the second partial finishing advantageously leads toLess wear and reduced edge cracks or microcracks at the edges.

The preferred embodiments described below can be implemented based on the first method and the second method. A common feature of both methods is that due to the temperature control of the heating or cooling process in the first and second regions, a different hardening of the two regions occurs, whereby the second region in the cooled or cold state has a reduced hardness compared to the first region.

According to a preferred design, the shaping and the first partial trimming are carried out substantially simultaneously. Preferably, both processing steps are performed in the same tool. Thereby, it is advantageously possible to combine two process steps performed with a heated member in a single process step. By performing these steps simultaneously, temperature losses that may occur between the forming and the first part trimming can advantageously be avoided. By performing the combined process of both shaping and trimming in one tool, the production can be accelerated and advantageously no transfer of components is required. The combination of thermoforming and thermal trimming may be performed, for example, by a forming tool having a cutting edge along the first portion length, such that upon pressing the members, separation occurs simultaneously along the first portion length.

According to a further preferred embodiment, the steel sheet component is straightened and/or calibrated during and/or after the trimming of the second part. Since the steel sheet component is warped in the second partial trimming due to the forces applied during cutting or due to internal stresses occurring during the phase transformation, the deformation during and/or directly after the second partial trimming can advantageously be corrected in this way. Preferably, according to the invention, the second partial trimming and the subsequent correction are carried out in a single tool, so that the trimming and calibration and/or straightening operations are integrated in this way in a single processing step.

According to a further preferred embodiment, the shaping takes place in a first tool, the first part is trimmed and cooled, and the second part is trimmed in a second tool. Advantageously, in this way, on the one hand, thermoforming is carried out in an integral manner by a single tool simultaneously with partial trimming, while subsequent partial trimming is carried out in another tool.

According to a further preferred embodiment, the trimmed remainder is removed from the sheet metal component after trimming of the second part. According to the invention, it is preferably provided that the mechanical connection of the sheet metal component is first completely retained in the first partial finishing and the final separation of the individual parts is only carried out by the second partial finishing. The separated trimmed residual portion may thereafter be removed from the steel sheet member in an additional step.

According to a further preferred embodiment, the coating or cladding is applied to the steel sheet component before heating, and the heating of the steel sheet component comprises a first phase in which a sixth temperature control of the steel sheet component is carried out such that a partial or complete alloying of the coating or cladding is achieved. The coating or cladding may be, for example, a zinc compound or an aluminum compound, especially an aluminum silicon coating. In a first stage of heating, the component is heated to below Ac₃And is kept at this temperature so that, in particular, austenitization has not yet taken place, but the AlSi-cladding, for example, is partially or completely alloyed to a sufficient extent. In a subsequent second heating stage, the component is then at least partially heated above Ac₃Until the material is at least partially austenitized to a sufficient degree for subsequent press quenching.

According to a further preferred embodiment, the coating consists of a zinc compound or an aluminum compound, in particular an aluminum silicon coating.

In addition to the first and second regions, a steel sheet component can be produced which can have one or more first regions which represent at least 30% by volume of the steel sheet component, wherein at least 95% by area of martensite and/or bainite, and possibly other microstructure constituents, are present. In particular, the steel sheet component can be substantially completely hardened, with the exception of the region adjacent to the second region, wherein the microstructure of the entire component consists of at least 95 area% martensite and/or bainite, possibly with further microstructure constituents. In addition to one or more first regions, one or more second regions may also extend over the steel plate member, the one or more second regions having a lower hardness than the first regions, if the member functions as needed to provide tailored properties on the steel plate member, particularly different mechanical properties during tailored tempering. The cutting profile does not necessarily have to extend in the second region. The sheet steel component may have a substantially constant material thickness or may also have a different material thickness (tailored rolling slab).

According to a further preferred embodiment, the steel sheet component is used as a structural component in a vehicle, in particular as a pillar, a longitudinal beam, a rocker, a pillar, a tunnel, or as a chassis component, in particular as a suspension arm, a composite steering axle.

Further details, features and advantages of the invention are given in the accompanying drawings and in the following description of preferred embodiments with reference to the drawings. The drawings show only exemplary embodiments of the invention, which do not limit the inventive concept.

Drawings

Fig. 1 shows a sheet steel component with a first and a second partial length of a cutting contour for trimming according to one embodiment of the method according to the invention.

Detailed Description

In fig. 1, a sheet steel component 1 is schematically shown in order to show a configuration of the method according to the invention. The manufacture of the steel sheet member 1 comprises shaping in a heated state, schematically represented by the form of the steel sheet member 1, the hardening process and the trimming along the dotted line causing the front part of the steel sheet member 1 to be completely separated from the rest. According to the invention, the trimming is carried out in two steps, wherein in a first partial trimming in the heated state the first partial length 2 of the steel plate component 1 is separated, and in a second partial trimming in the cooled or cold state the second partial length 4 is separated. The first partial length 2 preferably comprises the majority of the contour to be cut, so that the second partial length remaining after the first partial trimming only ensures mechanical joining of the workpiece, but can be separated with relatively little force in the second partial trimming. Thus, a lower hardness and a higher deformability of the component 1 in the heated state can be used for the first part finishing, so that, in addition to a reduction in the wear of the cutting tool, a smoother cutting surface is achieved and, in addition, crack formation during cutting is also reduced.

In order to also minimize the wear of the cutting tool during the second partial dressing, it is provided according to the invention that the temperature control of the steel sheet component 1 during heating and/or cooling is carried out in such a way that a first region with the greatest hardness and a second region 3 with a reduced hardness compared to the greatest hardness are formed. This is achieved by adjusting the local temperature profile in the first region such that a microstructure with a high martensite and/or bainite content is formed, while a further local temperature control in the second region 3 results in a lower or even no martensite and/or bainite content. In this illustration, the second region 3 consists of a relatively small region at the edge of the component 1, while the first region with the greatest stiffness comprises the entire rest of the component 1. In this way, advantageously only a small part of the entire component 1 has a reduced hardness. The high hardness of the first region does not adversely affect the finishing according to the invention, since the first partial finishing extending in the first region is carried out in a still unhardened state.

Description of the reference numerals

1 Steel plate Member

2 first part length

3 second region

4 second part length