JPH05131220A - Method for bending composite metal sheet - Google Patents

Abstract

PURPOSE:To suppress the occurrence of slippage between two layered steel sheets, and obtain a sharp bending line even by using bending dies with general purpose constitution, in bending a composite metal sheet interposed with a resin layer or an air layer between the two facings of metal sheets. CONSTITUTION:A method is adopted in that one side of the composite metal sheet 1 is crimped by a plane punch 2 and a plane pad 4 with a prescribed pad pressure P, and it is lowered towards a die 3 to bend the other side; a clearance C between the plane punch 2 and the die 3 is set at a value within the range of 80% to 110% of the thickness of the composite metal sheet 1; and the forming stroke L of the plane punch 2 is set at 10mm or more. Also, the above pad pressure P is a value determined by P>=(C/3XWXtXsigmaB)/4, wherein C is a constant being an integer of 1 or 2, W is the crimped width (mm) of the composite metal sheet, (t) is the thickness (mm) of the facing of metal sheet, and sigmaB is the tensile strength (N/mm<2>) of the facing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for bending a composite metal plate in which a resin layer or an air layer is interposed between two skin metal plates.

[0002]

2. Description of the Related Art In recent years, in order to prevent vibrations and noises generated from structural members of various machines and appliances such as furniture, electric parts and automobile parts, or other sources, they have been used as vibration damping members.
Starting with a damping steel plate with a viscoelastic resin layer with a vibration damping function in the middle, a composite metal plate with a soft metal layer with a vibration damping function in the middle and an air layer between the metal plates are formed. Composite metal plates and the like that have been laminated are developed and put to practical use. From the viewpoint of weight reduction, a composite metal plate using a lightweight material such as a resin or a light metal as an intermediate layer has been developed and is being put into practical use.

Because of their structure, these composite metal plates are inferior in formability such as deep drawing to single-layer metal plates, and are therefore mainly used for bending. But,
As shown in FIG. 5, these composite metal plates are press-bent using a punch (11) and a V-shaped die (12) that are conventionally applied to the bending of a normal single-layer metal plate. The composite metal plate (10) has a problem in that a so-called “seagull” phenomenon is likely to occur in the flange portion, which should be originally flat, is bent at an angle θ to the side opposite to the bending direction.

Therefore, in order to prevent the occurrence of the defective shape of the composite metal sheet due to the "seagull" phenomenon, various studies have been conventionally made on various aspects of the press bending method and bending die, and various proposals have been made. Has been done. A typical example of these proposals is, for example, a method of forming a difference in plate thickness between two front and back vibration-damping steel plates, and performing V-bending with the thinner steel plate being the bending outer side (JP-A-60- No. 72724) or a method of forming a notch or groove on either the front or back skin metal plate of the bending target part and performing V-bending along the notch or groove, etc. Some kind of treatment or pre-processing: As shown in [Fig. 6] and [Fig. 7], punch (21),
A steel plate receiver that changes the angle in a V shape in response to the descending of (31).
(23), (33) and the like are provided in the dies (22), (32) for a V-bending die (Japanese Patent Laid-Open No. 62-127125, 62-127127), and as shown in FIG. A method of arranging a steel plate (41) thicker than the composite metal plate (40) between the die (42) and the composite metal plate (40) and performing V-bending (JP-A-62-127126) For restricting the movement of the skin metal plate on the outer side of the bending of the composite metal plate during bending, such as: In response to the lowering of the punch (51), as shown in FIG.
When bending, such as a V-bending die (Japanese Patent Laid-Open No. 63-13620) provided with a pair of dies (52) that move to both sides under constant back pressure, a composite metal plate (50) Which gives "ironing" near the flange part of the outer metal plate on the outside of bending: As shown in Fig. 10 (a), composite metal plate (60)
A ridge (61) along the part to be bent, and then
(b) As shown in the figure, as in the method of bending in the direction opposite to the projecting direction of this ridge (61) (Japanese Patent Publication No. 63-43618),
For example, there is one in which the central portion of the portion to be bent is bent in a direction different from the original bending direction.

[0005]

However, the above-mentioned conventional techniques have the following problems, respectively. That is,
Although a method of making a difference in thickness of the skin metal plate or providing a notch or groove can suppress the occurrence of the "seagull" phenomenon and obtain a sharp bending line, the process is complicated and the productivity is increased. Not only inferior, but also due to the uneven thickness of the skin metal plate and the notches / grooves that affect the structural strength, the application range is greatly restricted. In addition, although the effect of suppressing the "seagull" phenomenon is recognized by the mold and method for restricting the movement of the outer skin metal plate on the outside of the bending, there is a limit to the suppressing effect, and further, [Fig. 6] and [Fig. The die shown in FIG. 7] has a complicated structure, and the method shown in FIG. 8 requires a steel plate for backup every time bending is performed, which is not economical. Further, in a die for imparting "ironing" to the skin metal plate on the outside of bending, in addition to the complicated structure, there is a problem that the "ironing" tends to cause flaws on the product surface.
Further, although the method shown in FIG. 10 can suppress the occurrence of the "seagull" phenomenon, in order to obtain the effect, the peeling of the front and back skin metal plates at the bent portion is inevitable, which causes a corrosion problem. In addition, the bending process is performed in two steps, resulting in poor productivity. Furthermore, in the conventional bending method adopting these butt-bending (V-bending) methods, there is a problem that it is difficult to obtain a sharp bending line, except for a method of making a difference in plate thickness on the skin metal plate or providing a notch or a groove. It has been desired to solve these problems.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and it is possible to suppress the occurrence of the "seagull" phenomenon under a bending die having a general-purpose structure, and yet it is sharp. It is an object of the present invention to provide a method for bending a composite metal plate that can obtain a bending line.

[0007]

In order to achieve the above object, the present invention has the following constitution. That is, the method for bending a composite metal plate according to the present invention is such that one side of the composite metal plate in which a resin layer or an air layer is interposed between two skin metal plates is subjected to a predetermined pad pressure by a flat punch and a flat pad. A method for bending a composite metal plate, which is sandwiched by P and is pressed down toward a die to bend the other side,
The clearance between the flat punch and the die is set to a value within the range of 80% to 110% of the plate thickness of the composite metal plate, the forming stroke of the punch is 10 mm or more, and the pad pressure P
Is a value satisfying the following formula. P ≧ (C / 3 × W × t × σ _B ) / 4 where C is a constant that takes an integer value of 1 or 2, W is a sandwiching width (mm) between the plane punch and the plane pad of the composite metal plate,
t is the thickness of the skin metal plate (mm), σ _B is the tensile strength of the skin metal plate (N / mm ² ).

[0008]

[Function] The "seagull" phenomenon that occurs when bending a composite metal plate is caused by the gap between the front and back skin metal plates at the flange portion due to the difference in the line lengths of the inner and outer surfaces that occur at the bent portion. In order to suppress the occurrence of the "seagull" phenomenon, during the bending process, the gap between the front and back skin metal plates on both sides of the bent part is regulated so that the outer skin metal plate at the bent part has a greater displacement than the inner skin metal plate. It is effective to cause a large amount of plastic deformation.

As a result of a comparative examination of various bending methods from this viewpoint, the present inventor clamps one side of a composite metal plate with a flat punch and a flat pad, and presses it down toward a die to push the other side. Focusing on the so-called L bending method of bending, bending processing under various processing conditions was performed under this method, and the following findings were obtained from the process and the result.

That is, in this method, "gull"
The occurrence of the phenomenon is greatly affected by the clearance of the mold and the molding stroke of the punch. This is one side
While the pad pressure between the flat punch and the flat pad suppresses the occurrence of misalignment between the front and back skin metal plates, the other side is drawn between the die and the flat punch and bent. , There is a gap between the front and back skin metal plates, but in the process, the contact between the die and the flat punch causes a difference in surface resistance between the front and back, and the difference in surface resistance causes the amount of deviation to change. Also, this is greatly influenced by the clearance between the die and the plane punch and the forming stroke. Therefore, when the clearance between the die and the plane punch and the punch forming stroke are set to appropriate values, the force in the bending direction applied to the skin metal plate on the die side (bending outside) is set to the punch side (bending inside). It is possible to control the deviation between the front and back skin metal plates by making it larger than the skin metal plate of), and consequently suppress the occurrence of the "seagull" phenomenon.

Based on this finding, further detailed examinations were made and the following conclusions were obtained. That is, as shown in the graph of [Fig. 4], the clearance of the mold is less than 110% (+ 0.1 mm) of the thickness (1.0 mm) of the composite metal sheet to be molded, which causes the "seagull" phenomenon. Can suppress the occurrence, but 110%
If it exceeds, even if the punch forming stroke is increased, the "seagull" phenomenon cannot be suppressed. In addition, the smaller the mold clearance, the higher the suppression effect, but if it is less than 80% of the plate thickness of the composite metal plate to be molded, mold galling is likely to occur and the stability and productivity of product quality will be hindered. It is not preferable.

On the other hand, the larger the punch forming stroke is, the more effective it is in suppressing the "seagull" phenomenon, but as shown in the graph of FIG. 4, the suppressing effect becomes saturated in the region of more than 10 mm. As it becomes more and more, in terms of productivity and press capacity, it is efficient to set it as small as possible at 10 mm or more.

Further, the pad pressure may be a pressure which can prevent the displacement between the front and back skin metal plates of the composite metal plate sandwiched between the flat punch and the flat pad, which is the upper and lower surfaces of the composite metal plate. Equal to or more than the minimum load required to bring the flat plate punch and the flat pad into close contact, that is, P ≧
The pad pressure P obtained by the mathematical expression represented by (C / 3 × W × t × σ _B ) / 4 is sufficient. [However, C is 1 or 2
, W is the sandwiching width (mm) between the plane punch and the plane pad of the composite metal plate, and t is the thickness of the skin metal plate (m
m) and σ _B are the tensile strength (N / mm ² ) of the skin metal plate. The value of the constant C is 1 when the rp (R of the punch shoulder) and rd (R of the die shoulder) are small, and 2 when they are large. ]

The method of the present invention has been completed on the basis of the various conditions grasped from the above-mentioned examination results, and the one side of the composite metal plate to be formed is quantified by a plane punch and a plane pad. While sandwiching the pad pressure P to regulate the deviation between the front and back skin metal plates in the flange portion on this one side, the other side of the composite metal plate is placed between the quantified flat punch and the die. By bending under the clearance and the forming stroke of the punch, the deviation between the front and back skin metal plates at the flange part on the other side is regulated, and the outer skin metal plate at the bent part is made to be more than the inner skin metal plate. Can also cause a large amount of plastic deformation and thus suppress the occurrence of the "seagull" phenomenon.

The punch forming stroke in the present invention means the distance from the lower surface of the punch to the rolling stop point from the upper surface of the die.

[0016]

EXAMPLE An example of the present invention will be described below with reference to FIG. [FIG. 1] is a conceptual explanatory view of a bending method according to an embodiment of the present invention, in which (a) is an explanatory view showing a state at the start of bending, and (b) is an initial stage of bending. FIG. 4 (c) is an explanatory diagram showing a state, and FIG. 6 (c) is an explanatory diagram showing a state at the end of bending.

In FIG. 1, (1) is a composite metal plate, and this composite metal plate (1) is a material to be molded, for example, two skin metal plates (1a), (1c). ) Between the viscoelastic resin layer (1
It is a vibration-damping composite metal plate with b) interposed.

(2) is a plane punch, which has a flat pressure surface (2a) at its lower end, and one side of which has a pressure surface (2a) at an angle of 90 degrees. Orthogonal forming surface (2
b), which is attached to a pressure ram of a press (not shown).

(3) is a die, and this die (3)
Is one side facing the molding surface (2b) of the flat punch (2),
A molding surface (3a) that has a vertical molding surface (3a).
, Is arranged at a fixed position below the plane punch (2) which is parallel to the molding surface (2b) of the plane punch (2) with a predetermined clearance C therebetween.

Here, in this embodiment, the dice (3)
The clearance C between the flat punch (2) and the flat metal punch
Set a value selected from the range of 80% to 110% of the plate thickness of (1) and set the forming stroke L of the flat punch (2) to 10 mm or more.

Reference numeral (4) is a flat pad, and the flat pad (4) has an upper end formed in a flat surface having the same outer shape as the pressing surface (2a) of the flat punch (2), and an upper surface of the flat pad (4). While facing the pressure surface (2a) of (2), it is supported by the cushion pin (5) and is arranged below the plane punch (2) so that it can move up and down under a predetermined back pressure. .. Also this flat pad
The upper limit of (4) is the height position where the upper surface is slightly higher than the upper surface of the die (3). Also this flat pad (4)
The cushion pin (5) for supporting is connected to a hydraulic mechanism of a press (not shown). This flat pad (4) is a flat punch (2) capable of pressing down the composite metal plate (1) set on the flat pad (4) under the above-mentioned structure.
It is sandwiched by and while the pad pressure P is being applied, the pad punch P is moved down in response to the pressure of the plane punch (2). The pad pressure P is obtained by bringing the front and back surfaces of the sandwiched composite metal plate (1) into close contact with the flat punch and the flat pad, and then the front and back skin metal plates.
A pressure that can suppress the occurrence of the deviation between (1a) and (1c) is sufficient, and the value is obtained by a mathematical expression represented by P ≧ (C / 3 × W × t × σ _B ) / 4. [Where C is a constant that takes an integer value of 1 or 2, W is the sandwiching width (mm) of the composite metal plate, t is the thickness of the skin metal plate (mm), and σ _B is the tensile strength of the skin metal plate (N
/ mm ² ), and the value of the constant C is 1 when rp (R of the punch shoulder) and rd (R of the die shoulder) are small, and 2 when they are large. ]

In this embodiment, first, a composite metal plate (1) as a material to be molded is formed into a die from the side of the flat punch (2), which has a desired flange length, on the side of the die (2b). (3)
Set out on the flat pad (4), facing out, ie with its intended bend line aligned with the shoulder of the flat punch (2).

Then, the flat punch (2) is pressed down,
As shown in the figure (a), the pressing surface (2a) of the flat punch (2) is brought into contact with the composite metal plate (1) on the flat pad (4). At this time, the pad pressure P is applied to the composite metal plate (1) by being sandwiched between the flat punch (2) which is pressed down and the flat pad (4) which is supported under a predetermined back pressure. It

Subsequently, when the flat punch (2) is pressed down with the composite metal plate (1) thus sandwiched, the die
The flange of the composite metal plate (1) exposed to the (3) side is
It contacts (3) and is bent and raised by the shoulder of this die (3) as shown in Figure (b).

Then, in the initial stage of this bending, a deviation between the front and back skin metal plates (1a), (1c) which causes the "seagull" phenomenon occurs near the bending line of the composite metal plate (1). However, since the pad pressure is applied to the side sandwiched between the flat punch (2) and the flat pad (4), no displacement occurs, and only the side of the flange that is bent and raised by the die (3). The gap will occur.

However, in this embodiment, since the flat punch (2) is further pressed from this state, that is, the forming stroke L thereof is set to 10 mm or more, the flange portion bent and raised by the die (3) continues. By pressing down the flat punch (2), as shown in (c), the forming surface (2) of the flat punch (2) is
It is drawn between b) and the molding surface (3a) of the die (3).

Then, in this process, the composite metal plate
The skin metal plate (1a) on the flat punch (2) side (bending outer side) of the flange portion of (1) is pressed against the forming surface (2b) of the flat punch (2), and the forming surface (2b While the bending movement ends with a small amount of relative movement to the), the skin metal plate (1c) on the die (3) side (bending outside) of the flange part
Since the relative movement of the die (3) with the forming surface (3a) is large,
Due to the contact with the molding surface (3a), a large surface resistance in a direction (bending direction) opposite to the drawing direction is received, and then the molding is completed. That is, skin metal plates on the front and back of the flange
For (1a) and (1c), the bending process ends after the surface resistances differing from each other are applied.

In this embodiment, since the surface resistance applied to the front and back surfaces of the flange portion bent and bent in this process is controlled by setting the clearance of the mold and the molding stroke to appropriate values, bending and bending is performed. Restricting the gap between the front and back skin metal plates in the flange portion, thereby causing plastic deformation with a larger amount of elongation than the bend inner skin metal plate in the bend outer skin metal plate in the bent portion and its vicinity, The occurrence of the "seagull" phenomenon can be reliably suppressed. Further, in this embodiment, since the gap between the front and back skin metal plates is regulated by setting the clearance and the molding stroke of the mold to appropriate values, the mold used is a general-purpose one with a very ordinary configuration. Can be dealt with.

It should be noted that, for example, a composite metal plate in which a "seagull" phenomenon is likely to occur, such as a composite vibration-damping metal plate in which a viscoelastic resin having a low adhesive strength is interposed in order to enhance vibration damping characteristics, is bent. When processing, set the mold clearance to a value smaller than the plate thickness of this composite metal plate (however, 80% or more of the plate thickness) and set the outer skin metal plate of the bending portion of the flange to be bent and raised. It is effective to add a light ironing to.

Finally, a concrete example of the method of the present invention will be described. A thickness of 0.05 between two thin steel plates with a thickness of 0.8 mm
Using a 1.65 mm thick resin composite type vibration damping steel sheet with a viscoelastic resin layer of mm in between, multiple test pieces with a width of 40 mm and a length of 200 mm were created. Under the bending mold and procedure, the flange was bent to a length of 60 mm.

In this embodiment, the shoulder R (rp) of the plane punch is
Is 1.0 mm, clearance C is 1.65 mm, pad pressure P is set to 800 (N) obtained with constant C = 1, while molding stroke L is 10 mm, 20 mm, 30 mm and 40 mmm.
The setting was changed to 5 mm as a comparative example. The cross-sectional shapes of the respective test pieces bent by these different forming strokes L are collectively shown in FIG.

As shown in FIG. 2, the forming stroke L
In the comparative example having a diameter of 5 mm, a "seagull" phenomenon occurred in the bent and bent flange portion, whereas in the example having a forming stroke L of 10 mm or more, a sharp bending R Nonetheless, the "seagull" phenomenon did not occur at all. Further, when the vicinity of the bent portion of each test piece after bending was examined, it was found that in the present embodiment, the bending outside and the vicinity of the bending outside skin metal plate had a larger elongation amount than the bending inside skin metal plate. Plastic deformation was recognized, and the excellent effect of the method of the present invention could be confirmed.

The embodiment described above is for so-called end bending (L bending), but as shown in FIG. 3 which is an explanatory view of another embodiment of the present invention, this L
By repeating the bending process, "U-shaped bending" without "seagull" phenomenon is possible.

[0034]

As described above, according to the method for bending a composite metal sheet of the present invention, the "seagull" phenomenon does not occur in a bending die having a general structure. Bending can be performed, and a sharp bending line can be obtained.

[Brief description of drawings]

1A and 1B are conceptual explanatory views of a bending method according to an embodiment of the present invention, in which FIG. 1A is an explanatory view showing a state at the start of bending, and FIG. 1B is a state in an initial stage of bending. An explanatory diagram showing
(c) is an explanatory view showing a state at the end of bending.

FIG. 2 is a diagram showing a vertical cross-sectional shape of a vibration damping steel plate according to an example of the present invention after bending.

FIG. 3 is an explanatory diagram of another embodiment of the present invention.

FIG. 4 is a graph showing the relationship between the clearance of the die and the punch forming stroke according to the present invention and the “seagull” angle of the composite metal plate.

FIG. 5 is an explanatory diagram of a “seagull” phenomenon of a composite metal plate that occurs in the composite metal plate in the conventional V-bending process.

FIG. 6 is an explanatory view of a conventional V-bending die.

FIG. 7 is an explanatory view of another conventional V-bending mold.

FIG. 8 is an explanatory diagram of a conventional V bending method.

FIG. 9 is an explanatory view of another conventional V-bending mold.

FIG. 10 is an explanatory view of another conventional bending method.

[Explanation of symbols]

 (1) --Composite metal plate (2) --Plane punch (3) --Die (4) --Plane pad (5) --Cushion pin C --Clearance L --Molding stroke

Claims (1)

[Claims] 1. One side of a composite metal plate having a resin layer or an air layer interposed between two skin metal plates is clamped by a plane punch and a plane pad at a predetermined pad pressure P, and this is directed to a die. A method for bending a composite metal plate, in which the other side is bent by pressing it down, and the clearance between the plane punch and the die is 80% to 110% of the plate thickness of the composite metal plate.
Within the range, the punch forming stroke is 10 mm or more, and the pad pressure P is a value satisfying the following formula. P ≧ (C / 3 × W × t × σ _B ) / 4 where C is a constant that takes an integer value of 1 or 2, W is a sandwiching width (mm) between the plane punch and the plane pad of the composite metal plate,
t is the thickness of the skin metal plate (mm), σ _B is the tensile strength of the skin metal plate (N / mm ² ).