JP6275521B2 - Method for manufacturing collision reinforcing material for vehicle - Google Patents

Description

  The present invention relates to a vehicle collision reinforcing material and a method for manufacturing the same.

  In the field of vehicle impact reinforcement materials such as door impact beams, hot press working methods (hot press working methods) tend to be used to improve the impact safety performance and weight of the reinforcing materials. is there. By the way, the hot press working method (hot press working method) starts with a hardenable metal plate material, heats the metal plate material to a predetermined high temperature, and heats the heated metal plate material at a relatively low temperature. This is a press working method that simultaneously achieves shaping and quenching by press molding with a press die.

  Conventionally, if you want to attach another part to a vehicle part made by hot press processing method (for example, if you want to attach an energy absorbing pad made of foamed resin to a door impact beam made by hot press processing method) Etc.), a nut for mounting another component (a mounting nut having an internal thread formed on the inner wall surface of the hole) was subsequently welded to the hot-pressed component (see FIG. 2). Incidentally, as a technique for projection welding a nut to a steel plate portion of an automotive structural material, there are, for example, Patent Documents 1, 2, and 3.

JP 2010-116592 A JP2012-082890A JP 2012-179646 A

However, there are various problems in nut welding for hot-pressed parts. For example, a): nut peeling due to lack of welding strength, b): screw failure due to spatter adhesion during welding (that is, splash of molten metal adheres to the screw groove or thread during welding and hinders the normal screw shape) B): Defects in screw pitch due to heat input during welding (deformation of screws); d) Delayed fracture of the weld due to residual stress generated during welding.
Patent Documents 2 and 3 consider the problem of delayed fracture, but do not solve all the problems of nut welding as described above.

The objective of this invention is providing the manufacturing method of the collision reinforcement material for vehicles in which the internal thread part for another component attachment was formed, not by nut welding.

The invention of claim 1 is a method of manufacturing a vehicle collision reinforcing material,
A heating step of heating a metal plate made of a quenchable metal to a high temperature of 800 ° C. or higher;
A pressing process for forming and quenching the metal plate material by press-molding the metal plate material in a high temperature state with a pair of relatively low temperature press dies and maintaining a clamping state with the pair of press dies; ,
When clamping with the pair of press dies and when the metal plate material is maintained at a temperature of 400 ° C. or higher, a part of the metal plate material is subjected to burring to protrude from the surface of the metal plate material. A burring step of forming a burring portion having a cylindrical flange portion;
When the mold is clamped by the pair of press dies and the metal plate is kept at a temperature of 400 ° C. or higher, tapping is performed subsequent to the burring, thereby forming an inner wall surface of the hole of the burring portion. A tapping process for forming the female screw part;
A mold opening step of separating the pair of press dies after the temperature of the metal plate is less than 400 ° C .;
It is a manufacturing method of the collision reinforcement material for vehicles characterized by comprising.

According to the method of the present invention, the plate-like portion is generally formed by performing a burring process on a part of the plate-like portion and a plate-like portion subjected to hot pressing without using nut welding. A vehicle collision reinforcing material comprising a burring portion having a cylindrical flange portion protruding from the surface of the rim and a female thread portion formed on the inner wall surface of the hole of the burring portion at an efficient and low cost. Can be manufactured. In particular, the burring process and the tapping process (formation of the internal thread portion) are performed in a state in which the metal plate material is maintained at a temperature of 400 ° C. or higher, that is, in an uncured state before the metal plate material is quenched. It can be performed smoothly and the residual stress can be suppressed as small as possible.

The invention of claim 2 is a method of manufacturing a vehicle collision reinforcing material according to claim 1 ,
In the burring step and the subsequent tapping step, a tapping punch is used, and the tapping punch has a tip portion formed as a punch portion for burring processing, and an intermediate portion following the tip portion is used for tapping processing. It is formed as a threaded part.

  By using a tapping punch in which a punching part for burring and a threaded part for tapping are continuously integrated, burring and subsequent tapping (formation of a female thread) can be performed efficiently in a short time. it can.

  ADVANTAGE OF THE INVENTION According to this invention, the collision reinforcement material for vehicles in which the internal thread part for another component attachment was formed can be prepared without using nut welding, and the various problems accompanying nut welding can be avoided. Moreover, component cost and manufacturing cost can be reduced.

The front view which shows an example of a door impact beam. Sectional drawing of the nut (conventional example) for another components attachment in the AA of FIG. Sectional drawing of the separate component attachment part (this invention) in the AA of FIG. The enlarged front view of the tapping punch used by this invention. The schematic sectional drawing which shows a series of processes of the manufacturing method according to this invention. The schematic sectional drawing which shows a series of processes of the manufacturing method according to this invention. The schematic sectional drawing which shows a series of processes of the manufacturing method according to this invention. The schematic sectional drawing which shows a series of processes of the manufacturing method according to this invention. The schematic sectional drawing which shows a series of processes of the manufacturing method according to this invention. The schematic sectional drawing which shows a series of processes of the manufacturing method according to this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an example of a door impact beam 10 which is a kind of vehicle collision reinforcing material. As will be apparent from FIGS. 5 to 10 described later, the door impact beam 10 has a so-called hat shape in cross-sectional shape, and is a long plate-like side that forms one of both hem portions of the hat shape. The part flange 11 is provided with at least one separate part mounting part 12. Conventionally, as shown in FIG. 2, the separate component mounting portion 12 is configured by a nut 14 welded to the surface of the side flange at a position above the hole 13 formed through the side flange 11. Incidentally, an internal thread portion 15 is formed on the inner wall surface of the central hole of the nut 14.

  On the other hand, in this embodiment, as shown in FIG. 3, the separate part mounting portion 12 in the long plate-like side flange 11 is formed by performing burring on the side flange 11. And a female screw portion 22 formed on the inner wall surface of the hole of the burring portion 21. Here, the burring portion 21 of the present embodiment includes a hole peripheral portion 23 that forms a hole (base hole 23a) having a depth corresponding to the plate thickness (T) of the side flange 11, and the hole peripheral portion 23. And a cylindrical flange portion 24 protruding from one surface of the side flange 11. The hole defined by the hole peripheral part 23 (base hole 23a) and the hole defined by the cylindrical flange part 24 (extension hole 24a) have the same inner diameter, and both holes (23a, 24a) A continuous series of through holes 25 is constructed. The through hole 25 is orthogonal to the side flange 11. And the internal thread part 22 is formed in the whole inner wall surface of this series of through-holes 25 by the tapping process.

  Next, with reference to FIGS. 4-10, one Embodiment of the manufacture procedure of the door impact beam 10 with the separate component attachment part 12 is described.

  In the present embodiment, a fixed lower die 31 and a movable upper die 32 are used as a pair of press dies. The upper die 32 is provided so as to be close (joined) and separated from the lower die 31 in the vertical direction. The lower mold 31 and the upper mold 32 have a concave / convex shape for cooperating to give a desired shape to the metal plate 40 (in FIG. 5, the central convex portion 32a is provided on the upper die and the central concave portion is provided on the lower die. 31a). As shown in FIG. 5, the upper die 32 is further provided with a tapping punch 34 and a drive mechanism 38 for the tapping punch 34.

  As shown in FIG. 4, the tapping punch 34 is a processing tool having a round bar shape as a whole. The tip portion (the lower end portion in FIG. 4) of the tapping punch 34 is configured as a burring punch portion 35. Further, an intermediate portion following the tip of the tapping punch 34 is configured as a tapping threaded portion 36 provided with a helical thread on its outer peripheral surface. The base end portion 37 (upper end portion in FIG. 4) of the tapping punch is operatively connected to the drive mechanism 38 (see FIG. 5).

  The drive mechanism 38 includes an electric motor and a gear transmission system (not shown), and is a mechanism for moving up and down in the vertical direction while rotating the tapping punch 34 around its central axis. By the action of the drive mechanism 38, the tapping punch 34 housed in the standby chamber 32b inside the upper mold can be moved in and out (projected and immersed) with respect to the lower mold 31. The lower die 31 is provided with a recess 31b as a receiving region for receiving the tip portion of the tapping punch 34 protruding from the upper die 32 at a position facing the tapping punch 34 attached to the upper die 32. Yes.

  Prior to hot pressing, a metal plate 40 as a starting material is prepared by blanking a material steel plate into a predetermined planar shape. The metal plate 40 is, for example, a high-tensile steel plate for hot pressing with a plate thickness of 1 to 2 mm.

  Subsequently, the blanked metal plate 40 is heated to a temperature of 800 ° C. or higher, preferably 800 to 1050 ° C. (about 900 ° C. in this example) by a heating device (not shown) such as an electric heating furnace. Then, the metal plate 40 in a high temperature state is conveyed at high speed toward the lower mold 31 in the mold open state as shown in FIG. 5 and set on the lower mold 31. At this time, the upper die 32 stands by above the lower die 31 and the tapping punch 34 is in a state of being immersed in the upper die 32.

  After the setting of the metal plate 40 is completed, the upper die 32 is moved downward toward the lower die 31, and when the upper die 32 reaches the bottom dead center position, the metal plate 40 is pressed by the upper and lower dies as shown in FIG. Molding (ie, shaping). FIG. 6 shows a state in which the metal plate 40 is press-molded into a cross-sectional hat shape, and in FIG. 6, the upper portion located on the left and right of the upper central projection 32 a (and the lower central depression 31 a). The side flange 11 of the door impact beam is formed by the lower surface portion of the mold 32 (and the upper surface portion of the lower mold 31). When the bottom dead center of the upper mold 32 shown in FIG. 6 is reached, the mold clamping is started (t = 0 seconds), and then this mold clamping state is maintained for a predetermined time (about 10 seconds in this example).

  Simultaneously with reaching the bottom dead center of the upper mold 32 (that is, starting mold clamping), the tapping punch 34 is lowered (projects downward) while rotating by the drive mechanism 38. Then, as shown in FIG. 7, the punch portion 35 at the tip of the tapping punch penetrates so as to push out a part of the right side flange 11 downward. As a result, the side flange 11 has a cylindrical flange. A burring portion 21 including the portion 24 is formed. This burring process is completed within about 1 second from the start of mold clamping (t = 0 second). For this reason, the metal plate 40 after press forming still maintains a temperature of 400 ° C. or higher, which is the temperature before starting martensitic transformation.

  Following the burring process of FIG. 7, the tapping punch 34 further descends while rotating. Then, as shown in FIG. 8, the threaded portion 36 of the tapping punch enters the through hole 25 of the burring portion 21 to form the female screw portion 22 in which a groove is spirally formed on the entire inner wall surface of the through hole 25. To do. This tapping process is completed in a time zone of 3 to 5 seconds from the start of mold clamping (t = 0 second). For this reason, the metal plate 40 after press forming still maintains a temperature of 400 ° C. or higher, which is the temperature before starting martensitic transformation. In addition, since the metal plate material 40 is maintaining the temperature of 400 degreeC or more, the plastic working (tapping process) by the threaded part 36 can be performed smoothly.

  When the tapping process on the entire through-hole 25 of the burring part 21 is completed, the drive mechanism 38 raises the tapping punch 34 while rotating it in the reverse direction, and removes the tapping punch 34 from the burring part 21 as shown in FIG. Then, it is immersed in the upper standby chamber 32b. It takes about 5 seconds for the tapping punch 34 to retreat. After about 5 seconds, that is, about 10 seconds after the start of mold clamping (t = about 10 seconds), the temperature of the metal plate material drops below 400 ° C. to about 200 to 250 ° C., and the martensitic transformation occurs. Occurs and quenching of the metal plate 40 is achieved.

  When quenching is completed after about 10 seconds have elapsed from the start of mold clamping, the upper mold 32 is separated from the lower mold 31 and the mold is opened as shown in FIG. The door impact beam 10 to which (the burring portion 21 and the internal thread portion 22) is provided can be obtained.

[Effect of the embodiment]
According to the present embodiment, the door impact beam 10 having the separate component mounting portion 12 can be obtained by a series of burring and tapping associated with hot pressing without using nut welding as in the conventional example. Accordingly, various problems associated with nut welding (refer to the above-mentioned items (a), (b), (c) and (d)) can be avoided. In addition, the cost of parts and the manufacturing cost can be reduced by not using the nut.

  According to the present embodiment, since a series of burring and tapping can be performed simultaneously or synchronously in the hot press process, the position accuracy of the processing location can be improved.

  Furthermore, even when the required depth of the internal thread portion 22 (shown as the internal thread stroke length L in FIG. 3) is obtained, according to the embodiment of FIG. The protrusion height h of the separate component mounting portion 12 can be reduced. That is, in the conventional example of FIG. 2, the female thread is not formed on the inner wall surface of the hole 13 formed through the side flange 11 but only on the inner wall surface of the center hole of the nut 14 welded to the surface of the side flange. 15 is formed. Therefore, the required female thread stroke length L is determined by the height h14 of the nut 14, and as a result, the protrusion height h of the mounting portion 12 in the conventional example of FIG. 2 is h = h14 = L.

  On the other hand, in the embodiment of FIG. 3, the internal thread portion 22 is formed on the inner wall surface of the series of through holes 25 constituted by the base hole 23 a formed through the side flange 11 and the extension hole 24 a of the cylindrical flange portion 24. Is done. Therefore, the required internal thread stroke length L is determined by the plate thickness T of the side flange 11 and the height h24 of the cylindrical flange portion 24 (L = T + h24). As a result, the protrusion height h of the attachment portion 12 in the embodiment of FIG. 3 is h = h24 = LT. Therefore, the protrusion height h (= h24) in FIG. 3 <the protrusion height h (= h14) in FIG. 2, and according to this embodiment, the separate part mounting portion 12 from the surface of the side flange 11 is compared with the conventional example. The protrusion height h can be reduced.

  Examples of the vehicle impact reinforcing material to which the present invention can be applied include bumper reinforcement, pillar materials (so-called A pillars, B pillars, and the like) that form a vehicle body skeleton, in addition to door impact beams.

10: Door impact beam (vehicle collision reinforcement),
11 ... side flange (plate-like part),
12 ... Separate component mounting part,
21 ... Burring processing part,
22 ... female thread,
23 ... peripheral part of hole,
23a ... Base hole,
24 ... cylindrical flange,
24a ... Extension hole,
25 ... A series of through holes (23a + 24a),
31 ... Lower mold (fixed press mold),
32 ... Upper mold (movable press mold),
34 ... Tapping punch,
35 ... Tapping punch part,
36 ... tapping punch threaded part,
40: Metal plate material.

Claims (2)

A method of manufacturing a vehicle impact reinforcement,
A heating step of heating a metal plate made of a quenchable metal to a high temperature of 800 ° C. or higher;
A pressing process for forming and quenching the metal plate material by press-molding the metal plate material in a high temperature state with a pair of relatively low temperature press dies and maintaining a clamping state with the pair of press dies; ,
When clamping with the pair of press dies and when the metal plate material is maintained at a temperature of 400 ° C. or higher, a part of the metal plate material is subjected to burring to protrude from the surface of the metal plate material. A burring step of forming a burring portion having a cylindrical flange portion;
When the mold is clamped by the pair of press dies and the metal plate is kept at a temperature of 400 ° C. or higher, tapping is performed subsequent to the burring, thereby forming an inner wall surface of the hole of the burring portion. A tapping process for forming the female screw part;
A mold opening step of separating the pair of press dies after the temperature of the metal plate is less than 400 ° C .;
The manufacturing method of the collision reinforcement material for vehicles characterized by comprising. In the burring step and the subsequent tapping step, a tapping punch is used, and the tapping punch has a tip portion formed as a punch portion for burring processing, and an intermediate portion following the tip portion is used for tapping processing. The method for manufacturing a vehicle collision reinforcing material according to claim 1 , wherein the method is formed as a threaded portion.

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