Method for producing a press-hardened door ring and at least one additional press-hardened component for a motor vehicle

Abstract

The invention relates to a method for producing a press-hardened door ring (210) and at least one additional press-hardened component (220) for a motor vehicle, comprising: - providing a shaped blank, comprising a first region having a door opening cutout, from which the door ring (210) is formed, and a second region, from which the additional component (220) is formed, the second region being located within the door opening cutout; - heating the shaped blank; - inserting the heated shaped blank into a press-hardening tool and carrying out a press-hardening operation in which both the door ring (210) and the additional component are shaped into their respective intended final geometries and hardened. A severing cut which severs the door ring (210) and the additional component (220) is carried out yet in the press-hardening tool.

Description

[0001] Description Method for producing a press-hardened door ring and at least one further press-hardened component for a motor vehicle. The invention relates to a method for producing a press-hardened door ring and at least one further press-hardened component for a motor vehicle. In so-called press hardening, steel sheet material suitable for press hardening is heated to austenitizing temperature and formed in a cooled tool (press-hardening tool) and simultaneously cooled, whereby a martensitic hardening effect results in an increase in hardness or strength (hardness and strength typically correlate). Press hardening as such is known from the prior art, for which reference is made below to corresponding patent and specialist literature. A so-called door ring is a sidewall body component that completely surrounds at least one door opening, i.e., the front door opening and / or the rear door opening.Such a door ring can be assembled from several sheet metal parts. Furthermore, such a door ring can also be manufactured as a single-piece sheet metal part, which offers many advantages, such as eliminating tolerance-sensitive joining processes, reducing production time, reducing weight (by eliminating joining flanges), and improving dimensional accuracy. DE 112017003027 T5 describes a method for manufacturing a door ring that includes a plurality of columns and pillars surrounding at least one door opening. The method initially includes providing a door ring blank that defines at least one door opening section. The door ring blank further includes at least one reinforcement section that extends through the at least one door opening section. The method is continued by heating the door ring blank and placing the heated door ring blank in a stamping die.The process then continues by hot-stamping the door ring blank in the mold to form the door ring and the at least one reinforcement. During the hot-stamping step, the at least one reinforcement is located in a free space between the column and spar sections of the door ring blank. After the hot-stamping step, the process continues by removing the stamped door ring and reinforcement from the stamping mold and transferring the formed components to a separate station for removing the at least one reinforcement, for example, by laser or cutting, from the door ring. After removing the at least one stamped reinforcement, the process continues by attaching the at least one reinforcement to the door ring at a desired location. In the process known from DE 112017003027 T5, a reinforcement part is formed in the area of ​​a door cutout that would otherwise be disposed of as sheet metal waste.This entails several advantages, as explained in DE 112017003027T5. Furthermore, the material utilization rate is also improved, or increased. Based on the previously explained prior art, the invention is based on the object of specifying an improved and, in particular, economically optimized method for producing a press-hardened door ring and at least one further press-hardened component. This object is achieved by the inventive method of the patent claim. Advantageous developments and refinements of the invention emerge from the dependent patent claims, the following description of the invention (this expressly includes features described as examples and optionally) and the figures. The inventive method for producing, ieFor the joint production of a press-hardened door ring for a motor vehicle and at least one further press-hardened component for a motor vehicle, the method comprises at least the following steps: providing a molded blank having a first region with a door opening cutout, from which the door ring is formed, and a second region from which the (at least one) further component is formed, wherein the second region is arranged within the door opening cutout; heating the molded blank; placing the heated molded blank in a press-hardening tool and performing a press-hardening process in which both the door ring and the (at least one) further component are formed into their respective intended final geometry (so that no further forming is required thereafter and they are also hardened or press-hardened), wherein a separating cut separating the door ring and the further component is carried out or introduced in the press-hardening tool.The door ring produced in this way and the additional component produced almost simultaneously (by which at least one additional component is meant) can be removed from the press-hardening tool as separate components and immediately processed independently of one another. A station specifically designed for separating the components is therefore no longer required. This reduces production time and equipment costs. Furthermore, energy savings also result. The process according to the invention is therefore particularly economical and has many other advantages. According to the invention, the door ring and the additional component are produced almost simultaneously from the same blank (form blank; see). The door ring is a one-piece (i.e., produced in one piece), press-hardened sheet metal part that has at least one completely bordered or circumferentially closed door opening, which is in particular a front door opening. The door ring can also have two completely bordered orhave circumferentially closed door openings (front door opening and rear door opening) (double door ring). The additional component is also a single-piece press-hardened sheet metal part, which is in particular a body or chassis component. The additional component can also be a supplementary component for the door ring. The blank is a so-called formed blank, which is formed in one piece and has an outline geometry determined by the components or sheet metal parts to be manufactured. The formed blank is made of a press-hardenable sheet steel material (e.g., 22MnB5 or CR1500), which can also have a scale and / or corrosion protection coating (e.g., an AISi or Zn coating). The formed blank is preferably flat. The formed blank is preferably monolithic (i.e., consisting of a single piece of sheet metal without joints) and, in particular, also has a homogeneous or uniform sheet quality and sheet thickness.(Sheet quality refers in particular to the mechanical properties of the steel sheet material, such as strength and elongation values. Thus, the door ring and the other component are not only one-piece, but also monolithic sheet metal parts. The disadvantages associated with welded blanks (tailored welded blanks or TWBs) therefore do not occur in the invention. The formed blank can also have different sheet thicknesses in some areas, so that the door ring and / or the other component produced from it have corresponding areas with different sheet thicknesses, which on the one hand enables particularly advantageous adaptation to locally different strength and / or crash requirements and on the other hand allows weight optimization. Such a formed blank can be formed by so-called flexible rolling. Flexible rolling and flexibly rolled sheet material are known from the prior art, for example.Reference is made to DE 102012110972 B3 (as well as to the prior art further cited therein). A blank or formed blank produced by flexible rolling can also be referred to as a tailored rolled blank (TRB). The formed blank has a first region from which the door ring is formed or produced, wherein this first region comprises at least a door opening cutout corresponding to a completely enclosed door opening of the door ring. D. This door opening cutout is provided for the formation of a completely enclosed or circumferentially closed door opening of the door ring and is therefore also completely enclosed or self-contained. Preferably, the outline geometry of the first region, i.e., the outer outline as well as the inner outline of the door opening cutout, corresponds at least approximately to the outline geometry of a flat development of the door ring to be produced. The molded board also has a second area from which the further component is formed oris produced, wherein this second region is arranged completely within the door opening cutout (of the first region) or is located within the door opening cutout. Preferably, the outline geometry of the second region corresponds at least approximately to the outline geometry of a flat development of the further component to be produced. The first region and the second region of the shaped blank are connected to one another. Preferably, the shaped blank has a plurality of connecting webs or the like which connect the first region and the second region, wherein in particular at least four or at least five connecting webs are provided. Preferably, the shaped blank is produced in a preceding manufacturing or production step by cutting out of a sheet metal semi-finished product (e.g. a sheet metal panel or a sheet metal strip), in particular a flexibly rolled sheet metal semi-finished product. The cutting out can be carried out by mechanical cutting, e.g.in a cutting or punching press with appropriately designed tools, or by means of a laser, e.g., in a laser cutting station. The preformed blank is first heated, which means heating to austenitizing temperature, which can be done, for example, in a furnace. Subsequently, the heated and still undeformed or flat blank is placed in the press-hardening tool, where the forming (hot forming) and hardening then take place as part of the press-hardening process. This preferred procedure is also referred to as direct press hardening. However, the invention is also applicable to indirect press hardening, where the blank is initially preformed. The method according to the invention is preferably carried out such that both the door ring and the other component are completely press-hardened and thus have a substantially martensitic structure.The method according to the invention can, however, also be carried out in such a way that different material structures or microstructure compositions are produced by locally different heating (of the mold blank) and / or by locally different cooling in the press-hardening tool and / or by other measures, so that different mechanical properties (in particular strength and elongation properties) are established in certain areas of the manufactured door ring and / or other component. The method according to the invention can also be carried out in such a way that only partial or partial press hardening is carried out, in particular with the aim of the manufactured door ring and / or the other component having at least one sub-area that is soft and ductile (so-called soft area). In particular, it is provided that the strength or hardness in such a soft area corresponds to the initial strength or hardness of the steel sheet material of the mold blank, so that no hardening or press hardening is necessary. This can, for example,by heating the press-hardening tool in the relevant tool area. According to the invention, a separating cut is made in the press-hardening tool, i.e., a separating operation is carried out, whereby the door ring and the further component are separated from one another and thus separated. The separating cut can comprise several separating points, in particular connecting webs, wherein the connecting webs are preferably severed in such a way that they remain on the door ring or the further component and can then possibly be severed during a later contour trimming. Furthermore, it can be provided that the connecting webs on both the door ring and the further component are severed or severed and then disposed of as waste pieces via chutes or the like from the press-hardening tool. The separating cut is preferably carried out before the sheet material (steel sheet material) has completely cooled or cooled down at at least one separation point(s).as long as the sheet material (or at least one separation point) is still warm and in particular still has a temperature of 100°C to 200°C, so that the strength is lower than when cooled. This can be achieved, for example, by not cooling the press-hardening tool locally in the area of ​​the at least one separation point or the separation webs, or even by heating it. The separation cut can be carried out after the door ring and the other component have been formed. However, the separation cut can also be carried out before the door ring and / or the other component have been formed or completely formed, which particularly means that the separation cut is carried out during the forming process, preferably towards the end of the forming process, especially when more than 90% and less than 100% of the forming has been achieved. This can be used to specifically influence the further or remaining forming process, for example bythe material flow at a specific point is promoted by the separating process. It is then preferably also provided that after the separating cut has been made or executed, at least the further component is held in the press-hardening tool in order to prevent slipping during further forming. This can be achieved, for example, using a spring-loaded hold-down device, e.g., in the form of a pressure stamp or the like. Furthermore, it is preferably provided that a contour cut, in particular an outer contour cut, of the door ring and / or the further component is carried out in the press-hardening tool. is carried out, whereby a contour cut (inner contour cut) of at least one door opening on the door ring can also be provided. Likewise, punching (to create holes) can also be carried out in the press-hardening tool. This is done in particular with the aim of ensuring that no further cutting operations are required on the door ring or other component after removal from the press-hardening tool.Analogous to the preceding explanations, the contour trimming and / or punching can be carried out before the sheet material at the cutting or punching line has completely cooled down, or while the sheet material (at the cutting or punching line) is still warm and in particular still has a temperature of 100°C to 200°C. This can also be referred to as hot trimming or hot punching. The press-hardening tool used to carry out the method according to the invention has at least a first cutting device with which the separating cut is carried out. The press-hardening tool can optionally have a second cutting device with which contour trimming and / or punching is carried out. The cutting devices of the press-hardening tool can each comprise at least one conventional cutting blade and an associated cutting die. The press-hardening tool preferably has a lower tool part and a relatively movable upper tool part and is installed in a press.The cutting devices can be controlled by means of gas pressure springs depending on the closing path. Preferably, the separation point(s) (at which the separation cut during forming (of the sheet steel material) in the press-hardening tool) are aligned such that the sheet steel material at the separation points is perpendicular or substantially perpendicular (e.g., 90° + / - 10°) to the tool closing direction (of the press-hardening tool), which means a local surface alignment of the sheet steel material at the separation points. This also applies in particular to the fact that the connection, in particular the connecting webs, between the first region and the second region (the formed blank) are at least partially formed during forming. This perpendicular alignment enables a comparatively simple construction of the first cutting device without a slide and promotes a long service life of the cutting device as well as optimal cutting results.Optionally, the door ring and / or the further component can be locally reinforced by at least one reinforcing element, as described in DE 112017003027T5. Such a reinforcing element can be applied to the mold plate before press hardening or even after press hardening to the press-hardened door ring or the press-hardened further component and secured by a material bond. This is also referred to as "patching." Within the scope of the invention, both the features described above and those explained below are applicable not only in the respective specified feature combination, but also in other feature combinations or on their own. This also applies to the features shown in the figures. The invention is explained in more detail below with reference to schematic (not to scale) figures.The features shown in the figures and / or explained below can, even independently of specific feature combinations, be general features of the invention and develop the invention accordingly. Figure 1 shows a molded blank for the inventive production of a press-hardened door ring and another press-hardened component. Figure 2 shows the door ring and the other component produced from the molded blank in Figure 1. The flat molded blank 100 shown in Figure 1 is made of a steel sheet material S in one piece and monolithically, with a homogeneous sheet thickness (B, 7 mm) and a homogeneous sheet quality. The molded blank 100 has a first region 110 from which the door ring 210 shown in Figure 1 is produced. The door ring 210 is a crash-relevant body structural component that is not visible when installed. The door ring 210 has a completely bordered or circumferentially closed front door opening 215.The first region 110 of the preformed blank 100 has a (front) door opening cutout 115 corresponding to the front door opening 215 on the door ring 210, as illustrated by a dashed line. The door opening cutout 115 is virtually completely surrounded or enclosed by the first region 110. The preformed blank 100 further has a hatched second region 120, from which the further component 220 shown in Fig. 2 is produced. The second region 120 is arranged within the door opening cutout 115 and connected to the first region 110 by means of several connecting webs 130. The preformed blank 100 has an outline geometry adapted to the components or sheet metal parts 210, 220 to be produced. To produce the components 210, 220, the provided molded blank 100 is first heated and, in the heated state, inserted into a press-hardening tool.A press hardening process is then performed in the press-hardening tool, in which both the door ring 210 and the additional component 220 are formed into their respective intended final geometry and hardened or press-hardened almost simultaneously (i.e., typically within one press stroke). Due to the relative position of the two components 210, 220, this simultaneous production can also be referred to as part-in-part production. A separating cut is then also performed in the press-hardening tool, in which the connecting webs 130 are severed or severed, thereby separating the door ring 210 and the additional component 220. Fig. 2 shows the press-hardened door ring 210 and the further press-hardened component 220 of their tool layers after press-hardening. (The severed or separated connecting webs 130 are not Both the door ring 210 and the further component 220 are formed in one piece and monolithically and have approximately the same sheet thickness as the formed blank 100, e.g. 7 mm).The two separate components 210, 220 can be easily removed from the press-hardening tool. This can be done using a gripper that picks up both components 210, 220 separately. Instead of just one additional component 220, several additional components can be manufactured simultaneously in the manner explained above. The door ring 210 further has a partially enclosed rear door opening 217, wherein the mold plate 100 is formed with a corresponding partially enclosed (rear) door opening cutout 117. This door opening cutout 117 can also be used, analogously to the previous explanations, to produce at least one additional press-hardened component. The rear door opening 217 can also be completely enclosed or closed all the way around (double-door ring). In this case, at least one further component 220 can be produced both in the corresponding front door opening cutout and in the corresponding rear door opening cutout.The one-piece and monolithic door ring 210 can also have at least one soft region W, within which the sheet steel material S is soft and at least softer and ductile than in adjacent regions. In the embodiment shown, the soft region W is located in the transition between the B-pillar and the sill and simultaneously forms a partial section of the border of the front door opening 215 and also the rear door opening 217, which entails many advantages. The press-hardened door ring 210 can have further soft regions. The further component 220 can also have at least one such soft region.

[0002] List of reference symbols 100 Form plate 110 First area 115 Door opening cutout 117 Door opening cutout 120 Second area 130 Connecting web(s) 210 Door ring (first component) 215 Door opening 217 Door opening 220 Further component (second component) S Sheet steel material W Soft area

Claims

Claims: Method for manufacturing a press-hardened door ring (210) and at least one further press-hardened component (220) for a motor vehicle, comprising the steps: providing a mold blank (100) having a first area (110) with a door opening cutout (115) from which the door ring (210) is formed, and a second area (120) from which the further component (220) is formed, wherein the second area (120) is arranged within the door opening cutout (115); heating the mold blank (100); 1. The heated form sheet (100) is placed in a press hardening tool and a press hardening process is carried out in which both the door ring (210) and the other component (220) are formed and hardened into their respective intended final geometries, whereby a separating cut is also made in the press hardening tool into the door ring (210) and the other component (220). 2.A method according to claim 1, characterized in that the parting cut is made before the sheet metal material (S) has cooled. A method according to any of the preceding claims, characterized in that the parting cut is made before the door ring (210) and / or the further component (220) have been formed. A method according to claim 1, characterized in that the further component (220) is formed in the press hardening tool after the parting cut has been made. A method according to any of the preceding claims, characterized in that contour trimming of the door ring (210) and / or the further component (220) is carried out in the press hardening tool. A method according to any one of the preceding claims, characterized in that the mold plate (100) has a homogeneous sheet metal grade and thickness. A method according to any one of the preceding claims, characterized in that the mold plate (100) is produced in a preceding step by cutting it from a sheet metal semi-finished product. A method according to any one of the preceding claims, characterized in that the restored press-hardened door ring (210) has at least one soft zone (W).

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