JP2017177841A - Vehicle door - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a door which is light-weight and has high strength.SOLUTION: A door includes: a door inner panel 1; and a door impact beam 9. The door inner panel is formed by a metal plate. Both end parts 17 of the door impact beam 9 are joined to the door inner panel 1. The door inner panel 1 includes a linear recessed part 3 intersecting with the door impact beam 9. The recessed part 3 protrudes toward the door impact beam 9.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vehicle door. More particularly, the present invention relates to an automobile door.

  An automobile door is mainly manufactured by combining a door inner panel and a door outer panel. Automobile doors have the role of ensuring passenger safety. Therefore, high strength is required for automobile doors.

  The door inner panel constituting the door is formed by pressing a metal plate such as a steel plate. Generally, since the shape of a door inner panel is complicated, a metal plate may be greatly deformed. In this case, the molded door inner panel may be cracked or wrinkled. Therefore, a highly workable metal plate is used as the material for the door inner panel. A highly workable metal plate has low strength. Therefore, a reinforcing member such as a door impact beam is attached to the door inner panel.

  The structure of an automobile door is disclosed in Japanese Unexamined Patent Application Publication No. 2015-113053 (Patent Document 1), Japanese Unexamined Patent Application Publication No. 2005-212598 (Patent Document 2), and Japanese Unexamined Patent Application Publication No. 2006-96205 (Patent Document 3).

  The door disclosed in Patent Document 1 includes a door inner panel and two door impact beams attached to the door inner panel. In the door of Patent Document 1, two door impact beams bear a collision load from the side of the vehicle. Therefore, the collision load applied to one door impact beam is reduced. Thus, Patent Document 1 describes that the strength of the door is improved.

  The door disclosed in Patent Document 2 includes a door inner panel and two door impact beams (guard bars) attached to the door inner panel. One door impact beam is curved and the other door impact beam is straight. When a collision load is applied to the door of Patent Document 2 from the side of the vehicle, a compressive force is generated in the curved door impact beam, and a tensile force is generated in the linear door impact beam. Thus, Patent Document 2 describes that the strength of the door can be maintained high from the start of the collision load to the end of the load.

  The door disclosed in Patent Document 3 includes a door inner panel, two door impact beams, and a reaction force generation mechanism that connects the two door impact beams. In the door of Patent Document 3, the collision load from the side of the vehicle is applied to the reaction force generation mechanism. The reaction force generation mechanism changes the direction of the collision load in the vehicle left-right direction to the vehicle vertical direction. The two door impact beams bear the load in the vertical direction. Accordingly, Patent Document 3 describes that the strength of the door is improved.

JP 2015-113053 A JP 2005-212598 A JP 2006-96205 A

  However, each of the doors of Patent Documents 1 to 3 includes two door impact beams in order to increase the strength of the door. For this reason, the doors of Patent Documents 1 to 3 are heavy and expensive. Moreover, since the doors of Patent Documents 1 to 3 each have two door impact beams attached to the door inner panel, the production efficiency is low.

  An object of the present invention is to provide a door that is light and strong.

  A door according to an embodiment of the present invention includes a door inner panel and one door impact beam. The door inner panel is made of a metal plate. The tensile strength of the door inner panel is 1200 MPa or more. Both ends of the door impact beam are joined to the door inner panel. The door inner panel includes a linear recess that intersects the door impact beam. The recess protrudes toward the door impact beam.

  The door according to the present invention is light and strong.

FIG. 1 is a perspective view of a door inner panel and a door impact beam according to the present embodiment. FIG. 2 is a sectional view of the door of the present embodiment. FIG. 3 is a cross-sectional view of the door inner panel and the door impact beam of the present embodiment at the time of a side collision. FIG. 4 is a perspective view of a door inner panel having a door impact beam different from that in FIG. 1 and the door impact beam. FIG. 5 is a cross-sectional view schematically showing a hot stamping device for manufacturing the door inner panel of the present embodiment. FIG. 6 is a cross-sectional view showing a stage in which the blank material S is sandwiched between the blank holders. FIG. 7 is a cross-sectional view showing a state when the pressing by the second punch is completed. FIG. 8 is a cross-sectional view showing a state when the pressing by the first punch is completed. FIG. 9 is a cross-sectional view showing a state during press working by a general hot stamping apparatus.

  The door according to this embodiment includes a door inner panel and one door impact beam. The door inner panel is made of a metal plate. The tensile strength of the door inner panel is 1200 MPa or more. Both ends of the door impact beam are joined to the door inner panel. The door inner panel includes a linear recess that intersects the door impact beam. The recess protrudes toward the door impact beam.

  When a collision load is applied to the door of this embodiment from the side of the vehicle, the door impact beam is deformed toward the door inner panel. A recess provided in the door inner panel intersects the door impact beam. Therefore, when the deformation of the door impact beam proceeds, the door impact beam hits the recess of the door inner panel. As a result, the door inner panel absorbs a part of the collision energy given to the door impact beam. The recess increases the moment of inertia of the cross section of the door inner panel. Therefore, even if the door inner panel bears a part of the collision energy, the door inner panel is hardly damaged. Further, such a high-strength door inner panel is formed by, for example, hot stamping. The tensile strength of the door inner panel is 1200 MPa or more. Since the strength of the door inner panel is sufficiently high, even if the door impact beam, which is a separate part, has a simple shape and low strength material, the strength of the door is high. Thereby, the strength of the door of this embodiment is high even if there is one door impact beam. Therefore, the door can be reduced in weight and the cost of the door can be reduced.

  Both ends of the door impact beam are attached to the door inner panel. Therefore, the center of the door impact beam is most easily deformed and easily damaged. Therefore, in order to increase the strength of the door, it is efficient to suppress deformation at the center of the door impact beam. Accordingly, the recesses preferably intersect at the center of the door impact beam.

  The intersection angle between the recess and the door impact beam is preferably 10 ° or more and 90 ° or less. This is because if the crossing angle is less than 10 °, the contact area between the recess and the door impact beam is difficult to stabilize.

  When the bending strength of the door impact beam is stronger than the bending strength of the door inner panel, the door inner panel may be greatly deformed following the deformation of the door impact beam. In this case, the door impact beam is difficult to hit the concave portion of the door inner panel. Therefore, deformation of the door impact beam may not be sufficiently suppressed. Therefore, the total plastic bending moment of the door impact beam is preferably smaller than the total plastic bending moment of the door inner panel.

  The door impact beam preferably includes a ridge or depression extending in the longitudinal direction. The raised portion and the depressed portion increase the moment of inertia of the cross section of the door impact beam. Therefore, the cost of the door impact beam can be further reduced. As a result, the cost of the door can be reduced.

  The door inner panel preferably has a top plate portion, an opening portion, and a vertical wall portion. The top plate is polygonal. The opening is formed in the top plate. The vertical wall portion extends from at least two or more adjacent sides of the top plate portion. Among the vertical wall portions, at least one set of the vertical wall portions adjacent to each other includes a stepped portion. The door inner panel faces the vehicle body parts such as pillars and seals the inside of the vehicle. When the adjacent vertical wall portion has a stepped portion, the airtightness in the vehicle can be enhanced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated. Hereinafter, the case where the door of this embodiment is a side door of an automobile will be described as an example.

  FIG. 1 is a perspective view of a door inner panel and a door impact beam according to the present embodiment. Referring to FIG. 1, the door inner panel 1 includes a top plate portion 2, a vertical wall portion 5, a step portion 6, and a flange portion 7. The door impact beam 9 includes both end portions 17. Both end portions 17 of the door impact beam 9 are joined to the door inner panel 1. The joining method is, for example, spot welding. Moreover, the both ends 17 of the door impact beam 9 may be joined to the door inner panel 1 via a bracket. FIG. 1 shows a case where both end portions 17 of the door impact beam 9 are joined to the step portion 6 of the door inner panel 1. However, the joining position of the both ends 17 of the door impact beam 9 is not limited to this case. Both end portions 17 of the door impact beam 9 may be joined to the flange portion 7, for example.

  The door inner panel 1 includes a linear recess 3 that intersects the door impact beam 9. More specifically, the concave portion 3 is provided in the top plate portion 2. The recess 3 protrudes from the top plate 2 toward the door impact beam 9. When a collision load is applied from the side of the vehicle (hereinafter also referred to as a side collision), the door impact beam 9 hits the recess 3 of the door inner panel 1. Thereby, since a part of collision energy given to the door impact beam 9 bears a door inner panel, the collision energy which the door impact beam 9 bears reduces. This point will be described in detail with reference to FIGS.

  FIG. 2 is a sectional view of the door of the present embodiment. FIG. 2 is a cross-sectional view seen from the vehicle front-rear direction. The door of this embodiment includes a door inner panel 1, a door impact beam 9, and a door outer panel 16. As shown in FIG. 2, the door impact beam 9 is disposed between the door outer panel 16 and the door inner panel 1. The storage position of the door glass in the door may be between the door impact beam 9 and the door outer panel 16 or between the door impact beam 9 and the recess 3 of the door inner panel 1. Moreover, the recessed part 3 of the door impact beam 9 and the door inner panel 1 may contact, and these may be joined by the adhesive agent or welding.

  In a side collision, the collision load P is first applied to the door outer panel 16. The door outer panel 16 is deformed and enters the vehicle inside (door inner panel 1 side). Next, the door outer panel 16 hits the door impact beam 9. As a result, a collision load is applied to the door impact beam 9 and the door impact beam 9 is deformed toward the door inner panel 1.

  FIG. 3 is a cross-sectional view of the door inner panel and the door impact beam of the present embodiment at the time of a side collision. Referring to FIG. 3, door impact beam 9 hits recess 3 of door inner panel 1. This is because the recess 3 protrudes toward the door impact beam 9. Thereby, the deformation of the door impact beam 9 is suppressed by the recess 3. Further, a part of the collision energy caused by the collision load P loaded on the door impact beam 9 is given to the door inner panel 1. Thereby, the collision energy given to the door impact beam 9 is reduced.

  In short, since a part of the collision energy is given to the door inner panel 1, even if the strength of the door impact beam 9 is lowered, the door impact beam 9 is hardly damaged. Therefore, in the door of this embodiment, the shape of the door impact beam 9 can be simplified, and a material having low strength can be used for the door impact beam. Thereby, it is possible to reduce the weight of the door while maintaining the strength of the door, and to further reduce the cost of the door. For example, as shown in FIG. 1, in the door of the present embodiment, even one door impact beam 9 can maintain the strength of the door.

  Further, by providing the recessed portion 3 in the top plate portion 2 of the door inner panel 1, the sectional secondary moment of the top plate portion 2 is increased. Furthermore, the tensile strength of the door inner panel 1 is 1200 MPa or more. Even if collision energy is given to the door inner panel 1 from the door impact beam 9, the door inner panel 1 is hardly damaged. Therefore, the safety of the passenger is ensured.

  As shown in FIG. 1, both end portions 17 of the door impact beam 9 are joined to the door inner panel 1. Therefore, the amount of deformation at the intermediate position of the both ends 17 of the door impact beam 9 (hereinafter also referred to as the center of the door impact beam) is the largest. In other words, the center of the door impact beam 9 is most easily damaged. As described above, when the door impact beam 9 hits the recess 3, the deformation of the door impact beam 9 is suppressed. Therefore, the recess 3 preferably intersects at the center of the door impact beam 9. Here, an acute angle among the angles formed by the recess 3 and the door impact beam 9 on the horizontal plane is referred to as an intersection angle θ.

  In reality, the load applied to the door impact beam 9 is not uniformly distributed in the width direction of the door impact beam 9. Therefore, if the crossing angle θ is less than 10 °, when the door impact beam 9 hits the recess 3, the contact area between the recess 3 and the door impact beam 9 is easy to move and is not stable. For example, it is assumed that the crossing angle θ = 0 °. In this case, even if the door impact beam 9 hits the recess 3, the door impact beam 9 slips and it is difficult to maintain contact with the recess 3. Therefore, the intersection angle θ between the recess 3 and the door impact beam 9 is preferably 10 ° or more and 90 ° or less.

  Further, when the strength of the door impact beam 9 is higher than the strength of the door inner panel 1, the door inner panel 1 may be deformed when the door impact beam 9 is deformed. In this case, the recess 3 of the door inner panel 1 is deformed in a direction away from the door impact beam 9. Therefore, the door impact beam 9 is unlikely to contact the recess 3. Therefore, the strength of the door impact beam 9 is preferably lower than the strength of the door inner panel 1. More specifically, the total plastic bending moment of the door impact beam 9 is preferably smaller than the total plastic bending moment of the door inner panel 1. Here, the total plastic bending moment refers to a bending moment applied when a cross section reaches a fully plastic state in an arbitrary cross section of the part.

  Hereinafter, the door impact beam and the door inner panel of this embodiment will be described in detail.

[Door Impact Beam]
FIG. 1 shows a case where the door impact beam 9 is made of a metal plate. In this case, the door impact beam 9 can be easily obtained by pressing a metal plate. FIG. 1 shows a case where the door impact beam 9 has a depression 18. The depression 18 extends in the longitudinal direction of the door impact beam 9. The depression 18 increases the moment of inertia of the cross section of the door impact beam 9. The door impact beam 9 may have a raised portion instead of the depressed portion 18. The raised portion also increases the sectional moment of the door impact beam 9. Thereby, the intensity | strength of the door impact beam 9 improves. Further, when the strength of the door impact beam 9 is sufficient, the door impact beam 9 may not have the depressed portion 18 or the raised portion.

  FIG. 4 is a perspective view of a door inner panel having a door impact beam different from that in FIG. 1 and the door impact beam. FIG. 4 shows a case where the door impact beam 9 is made of a metal tube. In this case, the door impact beam 9 is joined to the door inner panel 1 via the bracket 8. The joining method is, for example, arc welding.

  Whether the door impact beam 9 is a metal plate or a metal tube, the material of the door impact beam 9 is preferably steel. This is from the viewpoint of adjustment of strength and the like, cost, and the like. However, the material of the door impact beam 9 is not limited to steel and may be other metals. The other metal is, for example, aluminum, aluminum alloy, multilayer steel, titanium, magnesium or the like. Other than metals, there are CFRP (carbon fiber reinforced plastic) and resins. Moreover, it is preferable that the tensile strength of the door impact beam 9 is 1200 MPa or more. This is to absorb the collision energy at the time of a side collision and to ensure the safety of the passenger.

[Door inner panel]
With reference to FIG. 4, the door inner panel 1 of this embodiment consists of a metal plate. The metal plate that is the material of the door inner panel 1 is, for example, a steel plate, an aluminum plate, an aluminum alloy plate, a multilayer steel plate, a titanium plate, a magnesium plate, or the like. In the present embodiment, a case where the thickness of the metal plate is constant will be described. Therefore, the plate thickness of the door inner panel 1 is also constant over the entire area. Strictly speaking, however, a slight increase or decrease in sheet thickness occurs due to press molding.

  The planar shape of the top plate 2 is a polygon. The polygon may be, for example, a square or a pentagon. The corners of the polygon may be R-shaped. In FIG. 4, the case where the planar shape of the top plate part 2 is a pentagon is shown as an example. In the door inner panel 1, the vehicle upper side of the top plate portion 2 forms a belt line BL. The belt line BL is on the entrance / exit side of a window (not shown). Therefore, the vertical wall portion 5 does not exist in the belt line BL.

  The vertical wall portion 5 extends from at least two sides of the outer side of the top plate portion 2. In FIG. 4, as an example, the case where the vertical wall 5 extends from four sides 2A, 2B, 2C, and 2D excluding the vehicle upper side (belt line BL) among the five sides outside the top plate 2. Show. The vertical wall portion 5 faces the main body parts (pillars, side sills, etc.) of the automobile and enhances the inside sealing performance. Therefore, it is preferable that the vertical wall portion 5 extends from each side of two or more adjacent sides of the top plate portion 2. When the vertical wall portion 5 extends from two or more adjacent sides of the top plate 2, the vertical wall portions extending from each side are also adjacent. In FIG. 4, the case where the vertical wall part 5 extends perpendicularly | vertically with respect to the top-plate part 2 is shown as an example. However, the vertical wall portion 5 may not be strictly perpendicular to the top plate portion 2.

  The step portion 6 extends outward from the vertical wall portion 5A connected to the top plate portion 2. The outer edge of the stepped portion 6 is connected to the vertical wall portion 5B connected to the flange portion 7. In FIG. 4, the case where the level | step-difference part 6 is parallel to the top-plate part 2 is shown as an example. However, the step portion 6 may not be strictly parallel to the top plate portion 2. In FIG. 4, the case where the four adjacent vertical wall parts 5 have the level | step-difference part 6 is shown as an example. That is, the case where there are three sets of adjacent vertical wall portions 5 and the three sets both have a stepped portion 6 is shown. Further, FIG. 4 shows a case where one stepped portion 6 is provided on the vertical wall portion 5. However, the number of step portions 6 is not limited to one step, and may be a plurality of steps. The step portion 6 faces the pillar B of the vehicle body and seals the inside of the vehicle. In order to improve the sealing inside the vehicle, a seal member is disposed between the stepped portion 6 and the pillar.

  FIG. 4 shows a case where the door inner panel 1 has a stepped portion 6. However, the door inner panel 1 may not have the step portion 6. Even if the door inner panel 1 does not have the stepped portion 6, the stepped portion 6 is not necessary when the inside of the vehicle is sufficiently sealed. When the door inner panel 1 does not have the step portion 6, the door impact beam 9 is joined to the flange portion 7 of the door inner panel 1.

  The door inner panel 1 may have an opening 4. A part such as a speaker is attached to the opening 4.

  Moreover, when the door inner panel 1 consists of a steel plate, a tailored blank may be sufficient as a steel plate. Tailored blanks are roughly classified into tailored welding blanks (hereinafter also referred to as “TWB”) and tailored rolled blanks (hereinafter also referred to as “TRB”). TWB is obtained by integrating a plurality of types of steel plates having different thicknesses, tensile strengths, and the like by welding (for example, butt welding). On the other hand, TRB has a plate thickness changed by changing the interval between rolling rolls when manufacturing a steel plate. When a tailored blank is used, the strength can be strengthened by limiting to a necessary portion, and the plate thickness can also be reduced. A door inner panel using a tailored blank can also be applied to a door inner panel for an automobile. Thereby, a collision characteristic can be improved and weight reduction can be expected.

  As described above, the door inner panel of this embodiment bears a part of the collision energy given to the door impact beam. For this reason, the strength of the door inner panel is preferably higher. Specifically, the tensile strength of the door inner panel is 1200 MPa or more. This is because the door inner panel can absorb more collision energy as the tensile strength increases. However, a door inner panel having a high tensile strength and a complicated shape is usually difficult to mold. Specifically, the door inner panel having a complicated shape is likely to be wrinkled or broken during processing. The complicated shape includes, for example, a shape in which adjacent vertical wall portions 5 have stepped portions 6 such as the door inner panel 1 shown in FIG. Hereinafter, an example of a method for manufacturing a door inner panel having a complicated shape made of a steel plate and having a tensile strength of 1200 MPa or more will be described.

[Production method]
The manufacturing method of the door inner panel of this embodiment includes a preparation process, a heating process, and a press molding process by hot stamping. In the preparation process, a blank made of a steel plate is prepared. In the heating process, the blank is heated. In the press molding process, the heated blank is pressed and simultaneously the molded door inner panel is quenched. In the press molding process of the present embodiment, a hot stamping device is used as a press working device.

[Hot stamping device 10]
FIG. 5 is a cross-sectional view schematically showing a hot stamping device for manufacturing the door inner panel of the present embodiment. Referring to FIG. 5, the hot stamping apparatus 10 includes a punch 11 and a blank holder 14 as an upper die, and a die 15 as a lower die.

  The punch 11 includes a first punch 12 and a second punch 13. The first punch 12 is formed with the shape of the top plate portion of the door inner panel. The second punch 13 is formed with a stepped portion of the door inner panel. The punch 11 pushes the blank material S into the die 15 and forms the door inner panel.

  The blank holder 14 is disposed outside the second punch 13. The blank holder 14 faces the die 15. The blank holder 14 sandwiches the blank material S between the die 15 and the blank holder 14.

  The die 15 faces the first punch 12 and the second punch 13.

  The die 15 and the first punch 12 form the top plate portion 2 of the door inner panel 1 shown in FIG. The die 15 and the second punch 13 form the stepped portion 6 of the door inner panel 1 shown in FIG. The die 15 and the blank holder 14 form the flange portion 7 of the door inner panel 1 shown in FIG. Hereinafter, each process of the manufacturing method of this embodiment is demonstrated.

[Preparation process]
In the preparation step, a blank material made of a steel plate is prepared. The steel plate of the door inner panel of the present embodiment is preferably contained by mass% and carbon (C): 0.11% or more. When the steel plate contains 0.11% or more of carbon, the strength of the door inner panel after hot stamping can be increased.

[Heating process]
In the heating process, the blank is heated by a heating device (not shown). The blank material is preferably heated to the A1 transformation point or higher of the material. It is more preferable that the blank is heated to the A3 transformation point or higher. In hot stamping, the molded door inner panel is quenched at the same time as the blank material is press-molded. If the blank is heated to a point A1 or higher, the metal structure of the door inner panel after quenching becomes martensite and the strength is increased. The heating temperature is, for example, 700 to 900 ° C. The heating temperature is appropriately set depending on the material, the difficulty of molding, and the like. In hot stamping, the blank material is heated and softened, so that a complicated shape can be formed.

[Press forming process]
6-8 is sectional drawing which shows typically the press molding process of this embodiment. FIG. 6 shows a stage in which the blank material S is sandwiched by the blank holder 14. FIG. 7 shows a state when the pressing by the second punch 13 is completed. FIG. 8 shows a state when the pressing by the first punch 12 is completed.

  With reference to FIG. 6, the heated blank S is placed in the hot stamping apparatus 10. After the blank material S is arranged, the slide of the hot stamping device is lowered. Thus, the blank material S is sandwiched between the blank holder 14 and the die 15. However, the distance between the blank holder 14 and the die 15 is preferably larger than the thickness of the blank material S. That is, a gap is provided between the blank material S and the blank holder 14. The size of the gap is, for example, 0.1 mm. When the blank material S is brought into contact with the blank holder 14, the portion of the blank material S that contacts the blank holder 14 is cooled before the blank material S is press-molded. Therefore, since the cooling rate of the blank S is partially different, the strength of the molded product is different depending on the part. Therefore, it is preferable that a slight gap is provided between the blank holder 14 and the blank material S.

  Referring to FIG. 7, when the slide is further lowered, blank material S is drawn by punch 11 and die 15. FIG. 7 shows a case where the first punch 12 is at the same height as the second punch 13 when the blank material S is pushed by the second punch 13. That is, the case where the blank material S is pushed by the first punch 12 at the same time when the blank material S is pushed by the second punch 13 is shown.

  However, when the pressing of the blank material S by the second punch 13 is completed, the height position of the first punch 12 is not limited to the same height position as the second punch 13. At this time, the height of the first punch 12 may be higher than the second punch 13 or may be lower. That is, after the blank material S is pushed by the second punch 13, the blank material S may be pushed by the first punch 12. In addition, before the blank material S is pushed by the second punch 13, the blank material S may be pushed by the first punch 12. In any case, the pressing by the first punch 12 is not completed before the pressing by the second punch 13. It should be noted that the blank material is suppressed by the blank holder and the die until the second punch is formed.

  Referring to FIG. 8, after the pressing by the second punch 13 is completed, the first punch 12 is lowered and the blank material S is drawn. At this time, the portion of the blank S that is pushed in by the second punch 13 is restrained by the second punch 13. Thereby, the wrinkles etc. which generate | occur | produce near the level | step-difference part of a door inner panel can be suppressed. Hereinafter, this point will be described in detail.

[Suppression of cracks and wrinkles]
FIG. 9 is a cross-sectional view showing a state during press working by a general hot stamping apparatus. FIG. 9 shows an enlarged part of a die of a general hot stamping apparatus. Referring to FIG. 9, punch 210 is not divided in hot stamping apparatus 200. Therefore, when the punch 210 is lowered, a part S <b> 1 of the blank material S is not restrained by the punch 210 and the die 220. That is, a part S 1 of the blank S does not contact the punch 210 and the die 220.

  In hot stamping, the blank is cooled by contact between the blank and a punch, die, or the like. Therefore, in the stage shown in FIG. 9 during the press working, a part S1 of the blank S is not cooled. A part S1 of the blank S is cooled when the punch 210 is pushed further than the position shown in FIG. In short, when the door inner panel having the stepped portion provided on the vertical wall portion is formed by the punch 210 in which the top plate portion and the stepped portion of the door inner panel are integrally formed, a part S1 of the blank material S is Cooling later than other parts.

  If the cooling of the blank material S is partially delayed, the strength and ductility of the blank material S may be partially different. In this case, wrinkles and the like are likely to occur on the molded door inner panel. As shown in FIG.1 and FIG.4, when the adjacent vertical wall part 5 of the door inner panel 1 has the level | step-difference part 6, wrinkles etc. are easy to generate | occur | produce especially. When the strength of the molded door inner panel is high, wrinkles and the like are more likely to occur.

  The door inner panel manufacturing method of this embodiment uses a hot stamping apparatus 10 having a first punch 12 and a second punch 13 as shown in FIG. Thereby, the top-plate part 2 and the level | step-difference part 6 of the door inner panel 1 as shown in FIG.1 and FIG.4 are shape | molded by a separate punch. In addition, the pressing by the second punch 13 is completed before the pressing by the first punch 12. Thereby, when one punch forms the top plate portion 2, the other punch suppresses the step portion 6 of the door inner panel 1. Therefore, when the top plate portion 2 is molded, the portion of the blank material that is not restrained is reduced, and wrinkles of the door inner panel can be suppressed.

  In the above description, the case where the door of the present embodiment is a side door for an automobile has been described. However, the door of this embodiment is not limited to the side door for motor vehicles. The door of this embodiment can also be applied to a rear door or the like.

  The embodiments of the present invention have been described above. However, the above-described embodiment is merely an example for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and can be carried out by appropriately changing the above-described embodiment without departing from the spirit thereof.

DESCRIPTION OF SYMBOLS 1 Door inner panel 2 Top plate part 3 Recessed part 4 Opening part 5 Vertical wall part 6 Step part 7 Flange part 8 Bracket 9 Door impact beam 10 Hot stamping device 12 1st punch 13 2nd punch 14 Blank holder 15 Die 16 Door outer panel 17 Both ends of door impact beam 18 Depressed part BL Belt line S Blank material P Impact load θ Crossing angle

Claims (6)

A door inner panel made of a metal plate and having a tensile strength of 1200 MPa or more;
One door impact beam having both ends joined to the door inner panel,
The door inner panel includes a linear recess that intersects the door impact beam,
The recess is a door protruding toward the door impact beam. The door according to claim 1,
The recess intersects at the center of the door impact beam. The door according to claim 1 or 2,
The intersection angle of the said recessed part and the said door impact beam is a door which is 10 degrees or more and 90 degrees or less. The door according to any one of claims 1 to 3,
A door having a total plastic bending moment of the door impact beam smaller than a total plastic bending moment of the door inner panel. The door according to any one of claims 1 to 4,
The door, wherein the door impact beam includes a ridge or depression extending in the longitudinal direction. The door according to any one of claims 1 to 5,
The door inner panel has a polygonal top plate, an opening formed in the top plate, and a vertical wall extending from at least two adjacent sides of the top plate. The door in which at least one of the vertical wall portions of the vertical wall portions includes a step portion.

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