Method for producing a motor vehicle component, and a body component

Abstract

A method for producing a structural and/or safety-related motor vehicle component having at least one hot-formed and press-hardened part constructed from high-strength steel includes the steps of partially heat-treating a region of the motor vehicle component by heating the region to a heat-up temperature in a temperature range between 500 C. and 900 C.; maintaining the heat-up temperature for a duration of a holding time; and cooling down from the heat-up temperature in one or more phases. A body component constructed as a structural and/or safety-related motor vehicle component from a steel sheet blank that has been hot-formed and press-hardened includes joining flanges and/or coupling locations and/or safety-related parts, wherein the joining flanges, coupling locations and/or safety-related parts are partially heat-treated in several steps with the disclosed method.

Claims

1. A body component constructed as a structural component or as a safety-related component for a motor vehicle, said body component produced by hot-forming and press-hardening of a steel sheet blank, said body component having a first region which has been reheated to a heat-up temperature in a temperature range between 500 C. and 900 C., maintained at the heat-up temperature for a duration of a holding time, and cooled down from the heat-up temperature in at least one phase, said first region having a material structure of a ductility which is greater than a material structure of a hot-formed and press-hardened second region of the body component, said body component being produced by heat after treatment executed after the press-hardening, wherein a transition zone between the first region and the second region is less than 50 mm.

2. The body component of claim 1, further comprising a joining flange or a coupling location or a safety-related part or opening, said first region being part of the joining flange, coupling location, safety-related part or opening.

3. The body component of claim 1, for coupling with such body component at a coupling location, said first region being the coupling location.

4. The body component of claim 3, wherein the further body component is hot formed and press hardened and at least partially heat treated in the coupling location.

5. The body component of claim 3, wherein the further body component is produced by a sheet metal machining process.

6. The body component of claim 3, wherein the body component and the further body component are coupled in the coupling location by thermal joining, thereby producing a heat treatment zone which is heat treated.

7. The body component of claim 1, wherein the transition zone between the first region and the second region is less than 100 mm.

8. The body component of claim 1, wherein the body component is a part selected from the group consisting of an A-column, a B-column, a C-column, a D-column, a bumper, a crash box, a longitudinal front beam, a longitudinal rear beam, a tunnel, in form of a transmission tunnel, a rocker panel, a cross beam, a seat cross beam, a heel plate, a roof support beam, a floor panel, a sidewall, a vehicle door, a trunk lid, an engine lid, a roof area, and an instrument support with different added components.

9. The body component of claim 3, wherein the body component forms a bumper having a crash box formed by the further body component and coupled to the bumper at the coupling location by thermal joining, said first region being the coupling location.

10. The body component of claim 1, wherein the body component has an opening, said first region reducing a surface stress in an area of the opening.

11. The body component of claim 1, wherein the first region has a defined deformation in an event of a vehicle crash.

12. The body component of claim 11, wherein the defined deformation is wrinkling or folding.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Other features and advantages of the present invention will be more readily apparent upon reading the following description of currently preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which:

(2) FIGS. 1a), 1b), 1c) show different temperature curves of the individual steps of the heat treatment over time;

(3) FIG. 2 shows a perspective view of an A-column;

(4) FIG. 3 shows a perspective view of a frame tunnel;

(5) FIG. 4 shows a motor vehicle component consisting of two coupled components;

(6) FIG. 5 shows an instrument carrier made of several components; and

(7) FIG. 6 shows a bumper with various add-on components.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(8) Throughout all the figures, same or corresponding elements may generally be indicated by same reference numerals. These depicted embodiments are to be understood as illustrative of the invention and not as limiting in any way. It should also be understood that the figures are not necessarily to scale and that the embodiments are sometimes illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted.

(9) Turning now to the drawing, and in particular to FIG. 1a, there is shown a temperature curve as a function of time with the time intervals heat-up time (t1), holding time (t2), cooldown time first phase (t3) and cooldown time second phase (t4) according to the invention. In addition, the heat-up temperature (T1) and a first cooldown temperature (T2) are shown on the temperature axis.

(10) Starting with a hot-formed and press-hardened motor vehicle component which is essentially at a temperature below 200 C., this vehicle component is heated during the heat-up time to the heat-up temperature (T1). With a starting temperature of below 200 C., but still above room temperature, the residual thermal energy from the hot-forming and press-hardening process is used for the partial heat treatment within the context of the invention.

(11) Heat-up includes a linear temperature increase as a function of time. After the heat-up time (t1), the heat-up temperature (T1) is maintained during a holding time (t2). The heat-up temperature (T1) is held essentially constant during the entire holding time (t2). Temperature variations in form of a temperature increase or a temperature decrease are not illustrated, but may occur within the context of the invention during the holding time (t2) to affect the desired changes in the material structure, but also for cost reasons of the production process.

(12) At the end of the holding time (t2), a first cooldown to a cooldown temperature (T2) occurs. The temperature hereby decreases linearly during the cooldown time of the first phase (t3) to the cooldown temperature (T2). The cooldown temperature (T2) may be in a range between 100 C. and a heat-up temperature (T1).

(13) In a subsequent second cooldown phase, an additional linear temperature decrease takes place during the cooldown time of the second phase (t4). The temperature can hereby essentially be lowered to room temperature or to a desired (unillustrated) target temperature. It would also be feasible within the context of the invention to include additional cooldown phases, which are not illustrated.

(14) FIG. 1b shows a substantially similar temporal arrangement of the heat treatment, with the difference to FIG. 1a that the temperature increases progressively during the heat-up time (t1), whereas the cooldown during the first and second phase have each a decreasing temperature over time (t3, t4).

(15) FIG. 1c shows, in addition to FIGS. 1a and 1b, that the temperature curve has a diminishing temperature increase during the heat-up time (t1) and the functional dependence of the temperature decrease over time (t3, t4) is progressive during each of the various cooldown phases.

(16) In the context of the invention, it would also be feasible to combine the temperature dependence over time in mixed forms, such as progressive, linear and diminishing, during the holding time (t2).

(17) FIG. 2 shows a motor vehicle component 1 in form of an A-column 2 of an (unillustrated) motor vehicle body. Arranged on the respective sides 2a, 2b of the A-column 2 are joining flanges 3 which are heat-treated with the method of the invention. The A-column 2 then has high strength and hardness in its center profile sections 4 which guarantees protection of the passenger compartment in the event of a crash, whereas the joining flanges 3 have a rather ductile material characteristic relative to the center profile section, so that components attached to the joining flanges 3 (which are not illustrated here) remain connected with the A-column 2, without producing tears at the connecting locations characterized by the joining flanges 3.

(18) FIG. 3 shows a motor vehicle component 1 in form of a transmission tunnel 5. The transmission tunnel 5 has an opening 6, as well as joining flanges 3 disposed on both sides 5a, 5b, and a center profile segment 4. The end regions 7 of the opening 6 and the joining flanges 3 can here also be heat-treated with the method of the invention. In the event of the vehicle crash, the formation of tears, which would otherwise adversely affects the deformation characteristic of the motor vehicle component 1, here in form of the transmission tunnel 5, is intentionally prevented with the heat treatment of the end regions 7 of the opening 6.

(19) FIG. 4 shows a motor vehicle component 1 constructed of two coupled components 8, 9. In this illustrated embodiment, an upper (in relation to the image plane) component 8, a hot-formed and press-hardened component and a lower (in relation to the image plane) component 9 form a component produced with conventional forming methods. The two components 8, 9 are coupled together at coupling locations 10. The coupling locations 10 were heat-treated following the coupling process using a method according to the invention.

(20) FIG. 5 shows an instrument carrier 11 constructed of several individual components 12. The individual components 12 are here coupled with each other at coupling locations 10.

(21) FIG. 6 shows a bumper 13 with two crash boxes 14 and mounting plates 15 coupled to the crash boxes. The bumper 13 is coupled to the crash boxes 14 at coupling locations 10 through thermal joining.

(22) While the invention has been illustrated and described in connection with currently preferred embodiments shown and described in detail, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit and scope of the present invention. The embodiments were chosen and described in order to explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.