JPH08192233A - Piercing method - Google Patents

Abstract

PURPOSE: To prevent a pierce punch from being broken by piercing plate materials with different thickness after making the total piercing portion in the same thickness in a case of piercing with a pierce punch on a joining part of a step that the plate materials are butted and welded. CONSTITUTION: A piercing portion 6 of a joining part 4 of a thick metal plate part 2 and a thin metal plate part 3 of a door inner panel being formed with pressing and the vicinity thereof is set between an upper die 7 and a lower die 8 and the upper die 7 is lowered. The thick metal plate 2 and the joining part 4 among the piercing portion 6 forged and made in the same thickness with a thin metal plate part 3. Next, the piercing portion 6 formed flatly is mounted on a die 9, and a pierce punch 11 is lowered to the direction of arrow mark while holding the thick metal plate part 2 and the thin metal plate part 4 with a prescribed blank holding pressure by a blank holding plate 10. Therefore, even in the case of piercing from a side of the step being existed, an eccentric load is not applied on the pierce punch 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of piercing a joint formed by butting and welding plate materials having different thicknesses with a piercing punch.

[0002]

2. Description of the Related Art An automobile body is composed of a plurality of press panels, but in order to simultaneously achieve the strength, durability, and weight reduction required for improving fuel efficiency, which are required for the body,
As one method, press forming is performed after joining thin steel plates having different plate thicknesses by a welding method such as spot welding, laser welding or mash seam welding.

For example, as disclosed in Japanese Patent Publication No. Sho 49-12837, spot welding is performed by stacking materials having different plate thicknesses, and then compression molding is performed to form a substantially flat surface on one surface of the stacked portion. There is known a method for manufacturing a sheet metal part for a vehicle as described above.

Further, as described in Japanese Utility Model Laid-Open No. 62-82125, a pressing process for pressing and sandwiching unequal-thickness bonding materials is provided in the upper die and the lower mold to squeeze the unequal-thickness bonding materials. Press devices are known.

[0005]

According to the conventional technique, as shown in FIG.
As shown in FIG. 6, even after molding, the plate thickness is different on the joint part (weld part) 102 of the thick plate part (for example, thickness 1.4 mm) 100 and the thin plate part (for example, thickness 0.7 mm) 101 on one side. Since a step (difference in plate thickness) remains, when the piercing punch 103 has to be pierced from the side where the step exists, the step causes an eccentric load on the piercing punch 103 and breaks the piercing punch 103. There was a problem that problems such as the above occur.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to pierce a joint having a step formed by abutting and welding plate materials having different thicknesses. An object of the present invention is to provide a piercing method capable of performing piercing without breaking the piercing punch even when performing piercing with a punch.

[0007]

In order to solve the above-mentioned problems, the present invention provides a method of piercing with a piercing punch at a joint formed by abutting and welding plate materials having different thicknesses. The thick plate and the joint are forged to have the same plate thickness as the thin plate, and then the piercing portion is pierced with a piercing punch.

[0008]

In the pierced portion, the thick plate material and the joint are preformed by forging so that the entire pierced portion has the same plate thickness as the thin plate material and becomes flat. Then, the flattened piercing portion is pierced without applying an eccentric load to the piercing punch.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a perspective view of a door inner panel of an automobile body in which a piercing method according to the present invention is implemented,
FIG. 2 is a process explanatory view of the piercing method, and FIG. 3 is a perspective view of a side panel of an automobile body composed of a thick plate portion and a thin plate portion.

As shown in FIG. 1, a door inner panel 1 of an automobile body has a thick plate material (thick plate portion) 2 and a thin plate material (thin plate portion) 3 butted together, and the butted portion is laser welded. Then, it is pressed into a large piece of material.

At the joint portion (welded portion) 4 of the thick plate portion 2 and the thin plate portion 3 of the door inner panel 1 which is press-molded,
For example, when opening the hole 5 as the reference hole from the side where the step is present, first, as shown in FIG. 2A, the piercing portion 6 to be pierced, which is the joining portion 4 and the vicinity thereof, is raised. It is set between the mold 7 and the lower mold 8 and the upper mold 7 is lowered in the arrow direction.

Then, as shown in FIG. 2B, the thick plate material 2 and the joint portion 4 of the piercing portion 6 are press-formed to have the same plate thickness as the thin plate portion 3.

Next, as shown in FIG. 2 (c), the flatly formed piercing portion 6 is placed on the die 9, and the thick plate portion 2 and the thin plate portion are pressed by the wrinkle holding plate 10 at a predetermined wrinkle holding pressure. While holding down 3, the piercing punch 11 is lowered in the direction of the arrow to open the hole 5 shown in FIG. At this time, piercing punch 1
In the case of No. 1, since the pierced portion 6 formed flat is machined, the piercing punch 11 is not subjected to the eccentric load even when the piercing is performed from the side where the step exists.

Further, in addition to the door inner panel 1, as shown in FIG. 3, in the side panel 22 of the automobile body constituted by joining the thick plate portion 20 and the thin plate portion 21 by welding, the thick plate portion 20 and the thin plate portion are formed. Even when a hole such as a reference hole is formed in the joint 23 of the door 21, it is as effective as the door inner panel 1.

[0015]

As described above, according to the present invention, even when a piercing process is performed on a joint having a step formed by abutting and welding plate materials having different thicknesses, the entire piercing site is the same. Since the piercing is performed after the plate has been made thick, the piercing punch is not subjected to an eccentric load, and breakage of the piercing punch can be prevented.

[Brief description of drawings]

FIG. 1 is a perspective view of a door inner panel of an automobile body that is subjected to a piercing method according to the present invention.

FIG. 2 is a process explanatory view of a piercing method according to the present invention.

FIG. 3 is a perspective view of a side panel of an automobile body including a thick plate portion and a thin plate portion.

FIG. 4 is an explanatory view of a piercing method according to a conventional technique.

[Explanation of symbols]

1 ... Door inner panel, 2, 20 ... Thick plate material (thick plate part), 3, 21 ... Thin plate material (thin plate part), 4, 2
3 ... Joined portion (welded portion), 5 ... Hole, 6 ... Piercing portion,
7 ... upper mold, 8 ... lower mold, 9 ... die, 10 ... wrinkle retainer plate,
11 ... piercing punch, 22 ... side panel.

Claims (1)

[Claims] 1. A method of piercing a joint formed by abutting and welding plate materials having different thicknesses with a piercing punch. A piercing method, wherein the piercing portion is pierced with a piercing punch after the plate has the same thickness as a thin plate material.