DE102016103668B3 - Soft and hard-cut motor vehicle component and method for its production - Google Patents

Abstract

The present invention relates to a motor vehicle component (1) and a method for its production. The motor vehicle component (1) is produced by means of hot forming and press hardening. A trimming or punching is done by combining hot cutting and cold cutting.

Description

From the prior art it is known to produce motor vehicle components made of hardenable steel alloys. In this case, starting materials, for example provided in platinum form, are first heated at least regionally, in particular completely to above austenitizing temperature. In this warm state, the board is then placed in a hot forming tool and hot formed. If the forming is completed, the tool is cooled by appropriate cooling devices so quickly that a structural transformation takes place, preferably in martensite and thus the hot-formed component is press-hardened. In the hard state, such components with high-strength or very high-strength properties have tensile strengths of more than 1000 MPa.

Consequently, it is only possible with increased effort, the so hard material structure further processed mechanically, especially for punching, punching or trimming.

When cutting or punching a corresponding cutting tool is moved substantially perpendicular to a respective component surface, so that a shear occurs. At the resulting cutting edge thus arises on the cutting direction from top to bottom, a Umrollkante, a smooth cut portion, a fraction of fracture and a cutting edge. In the case of a hot cut, the straight cut portion with respect to the cross-sectional direction of the cutting edge extends over a higher proportion. In the case of a cut in the cold state, the fraction of fracture in the cross section at the cutting edge is correspondingly higher.

However, at the same time there is the problem that circumferential cutting edges on the component require a discharge of the cut or cut material. Therefore, a complete circumferential cutting or punching process of the edge of the component can be performed only partially in a thermoforming tool.

From the DE 10 2014 216 225 A1 a structural component is known in which the outer shell is produced as a press-hardened component and after the press-hardening the connecting flanges for the striking plate are cut. From the DE 10 2014 014 458 A1 is a hot-formed, press-hardened component known, which is cut after press hardening using a laser cutting machine. From the DE 10 2010 011 368 A1 are known press-hardened components, which have provided after the press-hardening for cutting operations intended areas, which are heat-treated.

Furthermore, from the DE 10 2007 050 907 A1 in the case of a press-hardened sheet-metal profile, it is known to pre-impress a region for a hole before hot-forming with a limited depth and to press in the opposite direction after the press-hardening.

From the DE 10 2005 051 403 B3 It is also known, for the hard cutting after press hardening, to provide the regions to be cut with a material thickness reducing impression in order to allow trimming by means of hard cutting.

Object of the present invention is therefore to show a motor vehicle component having a correspondingly high precision and quality at a cutting edge and a method for its production.

The aforementioned object is achieved by a motor vehicle component having the features in claim 1.

The present invention is further achieved with a method for producing a motor vehicle component with the features in claim 7.

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

The motor vehicle component is hot formed and press-hardened. This means that initially a blanket was austenitized and then hot worked. Again, subsequently, the thermoformed component has been cooled so rapidly that it is press hardened. According to the invention, the component has a cut edge with a length. The cut edge may be a cut edge that partially or completely surrounds the component outside. However, it may also be a cut edge, which is formed inside the motor vehicle component, for example at a recess or a hole. Also, both inner and outer cut edges can be formed simultaneously on the motor vehicle component. The following benefits apply accordingly. The cut edge has over a hard cut length of less than 30% of the length in its cross-section, thus in cross-sectional height, a fraction greater than 50%. Over the remaining soft-cut length, thus over more than 70% of the length, the cut edge in cross-sectional height has a fractional fraction of less than 40% and a smooth cut portion greater than 50%.

The respective proportion of smooth cut portion and fracture fraction thus extends over the cutting edge over a respective percentage of the height. The cutting edge is also referred to as the section height of the cut edge.

According to the invention, the motor vehicle component is produced in that the high smooth cut portion of the soft cut length is produced in the warm state, in particular during or after the hot forming. The fraction of fracture in the hard cut length, however, is produced in the residual warm or cold state by a corresponding cold cut. The soft cut can be referred to as hot cutting or hot cutting in the context of this invention. The hard cut can also be referred to as cold cutting or cold cutting.

The motor vehicle component itself is made of a hardenable steel alloy, in particular a manganese-boron steel, for example 22 MnB5. However, the motor vehicle component may also have a coating, for example an anti-corrosion coating, in particular an aluminum-silicon coating. The motor vehicle component can also be formed from a composite panel steel, for example a CPH steel (corrosion proteced hot-forming steel). For this purpose, a stainless steel-plated hot-forming steel is used in particular. The motor vehicle component has a tensile strength greater than 1300 MPa, in particular greater than 1500 MPa and particularly preferably greater than 1600 MPa.

In a preferred embodiment variant, the soft-cut length extends over more than 75% of the length of the cut edge, in particular more than 80%, preferably more than 85%, particularly preferably more than 90% and very particularly preferably more than 95%. Alternatively or additionally, the straight-cut portion of the soft-cut length in cross-sectional height is formed over more than 60%, in particular more than 70%, preferably more than 80%, extending. Thus, it is possible to trim the motor vehicle component before, during or immediately after the hot deformation in the warm state. This cutting or punching process then extends over a large part of the length of the cut edge and can also be referred to as a soft cut length. In particular, the trimming process can be carried out completely, this means that the component is not only cut in cross-section, but is completely cut through the soft cut length. A correspondingly high proportion of the smooth cut is recorded at the cutting edge over the soft cut length. The corresponding hard cut length then has a fraction greater than 50% in cross section. This means that it can be cut partially warm, the final trimming in cross-section height, however, is performed in the hard cut or cold cut. However, the hard cut length is preferably completely cold cut. Correspondingly high is the fractional part, as this hard cut length is cut in the hard state. The terms hard cut length and soft cut length are thus not to be understood in terms of the temporal production process. The hard cut length and the partial cut length can also consist of individual lengths. The respective soft cut length or hard cut length is then a sum of the corresponding length sections.

Furthermore, a cutting edge preferably extends in cross-sectional height, or the cutting edge is oriented in cross-sectional height. A cut edge of the hard cut length with a higher fraction fraction furthermore preferably has an angle to a cut edge of the soft cut length with a higher proportion of smooth cut. This is due to the fact that unfavorable angular positions result in part on the hot-formed motor vehicle component with respect to the cutting tools entering the motor vehicle component in the cutting direction. Partly bulges, bends or the like are formed on the motor vehicle component. This is the case in particular for large-area components and structural components of the sidewall structure. Here is another significant advantage of the invention. The motor vehicle component is trimmed during or after the warm forming process in the warm state. In this case, a cutting tool which enters in the cutting direction is used as part of the hot forming and press hardening tool. Then, the motor vehicle component is either directly press-hardened in the same tool and transferred to a following tool and cut here in the hard or cold state. The angular position to the motor vehicle structural component, with which the cutting tool of the cold cutting process enters, is different from the angular position of the generated cut edge of the soft cut. By relocation of the component, the different angular positions are generated.

The present invention further relates to a method for producing a hot-formed press-hardened and cut or stamped motor vehicle component. The method is inventively characterized by the fact that the motor vehicle component to be produced is hot cut at a cut edge to be produced over a soft cut length or hot cut length of the length of the cut edge greater than or equal to 70% and that the remaining part length, also called hard cut length of the produced Cutting edge is cut in a hard-cut process, especially in the cold state, wherein the angular position of the motor vehicle component, in particular in the region of the cut edge to be produced to the cutting direction of the soft cut of the angular position of the motor vehicle component, in particular at the cut edge to be produced, is different from the cutting direction of the hard cut.

Furthermore, the method is characterized in that the soft cutting, during or after the hot forming is performed as a hot cutting. In particular, the hot cutting is carried out at a temperature greater than 450 ° C, in particular greater than 550 ° C, preferably greater than 600 ° C.

The method is further characterized in that the hard cut is carried out during or after the press-hardening. The hard cut is carried out either in the press-hardening tool or preferably in a tool that is different from the press-hardening tool. The press hardening tool itself can preferably be integrated into the hot forming tool. Hot forming tool and press hardening tool are the same tool in this case. However, the press hardening tool may also be a separate tool from the hot forming tool. This press hardening tool can in turn have a hard cutting device. However, the hard cutting device can also be a separate tool from the press hardening tool.

The method thus combines according to the invention the possibility that during hot cutting, preferably a complete cut is made through the component via the soft-cut length or hot-cut length, in particular thus a complete cut edge is produced. However, the cut parts remain on the component due to the still to be produced cut edge in the downstream hard cut or cold cut. This partial length of preferably less than 30% of the length of the entire cut edge to be produced can now be moved to a preferred angular position relative to the cutting direction of the cold cut due to the rearrangement of the component, in particular taking place therewith.

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

1 a motor vehicle component produced in accordance with the invention having a circumferential as well as an internal cutting edge,

2a and b is a partial cross-sectional view through a cut edge made by hot cutting and cold cutting,

3a to c from each other different angular positions in hot cutting and cold cutting and

4 a manufactured according to the invention motor vehicle component in cross section.

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

1 shows a motor vehicle component produced according to the invention 1 , This has an outside circumferential cut edge 2 on as well as an internally encircling cutting edge 3 at a recess 4 , The cutting edge 2 . 3 runs with a length L outside or inside respectively, shown here, completely. An exemplary drawn hard cut length 5 in the upper region of the motor vehicle component 1 extends over less than 30% of the total length L of the outer circumferential cut edge 3 , In this section of the hard cut length 5 has not shown section height of the cut edge 2 a fraction greater than 50%. The remaining soft cut length 12 the cutting edge 3 not from the hard cut length 5 is covered, has in cross-sectional height a fraction of less than 40% and a smooth cut portion greater than 50%. The hard cut length 5 can also be in several lengths 5a . 5b split. For example, located in the lower part of the motor vehicle component 1 , The sum of the lengths 5a . 5b and if necessary. 5 is then according to the invention less than 30% of the length L. The remaining cut-off length 12 is then the hot cut length.

In 2a and b is the cut edge 2 shown. This has a running on the image plane from top to bottom cutting edge 6 on. In 2a shown is the cutting edge 2 in the area of the hard cut length 5 , The cutting edge extending from top to bottom 6 has a smooth section at the top 7 and in the lower part a fractional part 8th on. The total section height H of the cutting edge 6 also extends to the image plane from top to bottom. The smooth cut portion 7 extends over less than 50% of the section height H and the fractional part 8th over more than 50% of the section height H. In 2 B is the cutting edge 6 in the area of the remaining soft cut length 12 , produced by a hot cut, shown. Again, the cutting edge extends 6 over the entire cross-sectional height H. It can be seen that the smooth cut portion 7 extends over more than 50%, in particular more than 60% and more preferably more than 75% of the cross-sectional height H, wherein the fraction fraction 8th extends over less than 40% of the section height H.

3a and Fig. b show an embodiment variant of the present invention, showing a cutting direction 9 of hot cutting. This creates at the circumferential cut edge 2 a cutting edge 6.12 , so that here shown a component surface 10 approximately at a right angle α to the cutting direction 9 the soft cutting is located. 3b shows the subsequently performed hard cut. Here is a cutting direction 11 hard cutting at an angle β to the component surface. The angles α of the soft cutting and β of the hard cutting are different from each other. This offers the particular advantage that the cutting direction 9 the soft cutting in a separate tool or after rearrangement of the motor vehicle component 1 separated from the cutting direction 11 the hard cutting oriented to the component runs.

3c shows the cut edges 6.5 and 6.12 superimposed. The cutting edge 6.5 lies at an angle γ to the cutting edge 6.12 ,

4 shows a cross section through an inventively manufactured motor vehicle component 1 , To a component surface 10 is a cutting edge on the left side of the picture 6.12 shown to the soft section. On the right side of the picture is a cut edge 6.5 shown to the hard cut. The cutting edge 6.12 and 6.5 run at an angle γ to each other. By rearrangement of the motor vehicle component, shown here in a large-scale outward curvature, it is possible in each case at vertically fitting cutting direction, the angular positions of the cut edges 6.5 and 6.12 to create each other.

LIST OF REFERENCE NUMBERS

1

Motor vehicle component

2

cutting edge

3

Cutting edge too 4

4

recess

5

Hart cut length

5a

 longitudinal section

5b

 longitudinal section

6

cutting edge

6.5

 Cut edge of hard cut

6.12

 Cut edge of soft cut

7

Flush-cut percentage

8th

fractional part

9

Cutting direction for soft cutting

10

 component surface

11

 Cutting direction to the hard cut

12

 Soft cutting length

α

 angle

β

 angle

γ

 angle

L

length

H

Section height

Claims (2)

Motor vehicle component ( 1 ), which is hot-formed and press-hardened and has a cut edge ( 2 . 3 ) having a length (L), characterized in that the cut edge ( 2 . 3 ) over a hard cut length ( 5 ) of less than 30% of the length (L) in cross-sectional height (H) has a fractional part ( 8th ) greater than 50% and over a remaining soft-cut length ( 12 ) in cross-sectional height (H) a fraction ( 8th ) of less than 40% and a 7 ) greater than 50%. Motor vehicle component according to claim 1, characterized in that it is coated, in particular with an AlSi coating or that it is formed from a hot-forming steel clad with stainless steel. Motor vehicle component according to claim 1 or 2, characterized in that a cut edge ( 2 ) is formed on an outer peripheral edge and / or that a cut edge ( 3 ) at an inner recess ( 4 ) is trained. Motor vehicle component according to one of claims 1 to 3, characterized in that it at least partially has a tensile strength greater than 1300 MPa, in particular greater than 1500 MPa, preferably greater than 1600 MPa. Motor vehicle component according to one of claims 1 to 4, characterized in that the remaining soft-cutting length ( 12 ) over more than 75%, in particular more than 80%, preferably more than 85% of the length (L) of the cut edge ( 2 ) and / or that the smooth-cut portion ( 7 ) of the remaining soft cut length ( 12 ) in cross-sectional height more than 60%, in particular more than 70%, preferably more than 80%. Motor vehicle component according to one of claims 1 to 5, characterized in that in cross-sectional height (H) a cutting edge ( 6 ) and a cut edge ( 6.5 ) of the hard cut length ( 5 ) at an angle (γ) to a cutting edge ( 6.12 ) of the soft-cut length ( 12 ) with a greater proportion of smooth sections ( 7 ) is oriented. Method for producing a motor vehicle component according to the features of at least claim 1 by means of hot forming and press hardening, characterized in that the motor vehicle component to be produced ( 1 ) in the warm state at a cut edge to be produced ( 2 . 3 ) over a soft-cut length ( 12 ) greater than or equal to 70% is hot cut and that the remaining hard cut length ( 5 ) of the cutting edge ( 2 . 3 ) is cut in a cold cutting step, wherein the angular position (α) of the motor vehicle component ( 1 ) to the cutting direction ( 9 ) of the soft section of the angular position (β) of the motor vehicle component ( 1 ) to the cutting direction ( 11 ) of the cold section is different. A method according to claim 7, characterized in that the soft cutting is carried out during or after hot working. A method according to claim 7 or 8, characterized in that the hard cut after the press hardening is performed. Method according to one of claims 7 to 9, characterized in that the hard cut is performed in a different tool from the press hardening tool.

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