JP2005021955A - Method and device for bending metal plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To propose a bending method for a metal sheet component by which a bent part with a projected corner part without roundness can be formed. <P>SOLUTION: A projecting plate part 12 with a specific width, which is projected from the end face 11 of the metal sheet component 10, is made as a bent plate part 12A by bending it at a shallower angle than a target angle (a bending process). The bent root at the bent plate part 12A is located at a position outside from the end face 11. Cut faces 13, 14 formed in-between the end face 11 are made so as not to be exposed in a bent state. The length at the bent plate part 12A is made longer than that of at the bent part 12B which can be finally obtained. Next, pressing 15 is applied to the bent root part 12a inside the bent plate part 12A. The outer face 12c of the bent plate part 12A is pushed into the end face 11 while compressing the bent plate part 12A from its tip face 12b to the length direction in that state (a compressing process). The bent part 12B with the projected corner part without the roundness can be formed without increasing the number of the processes. Accordingly, the reduction of its plate thickness can be suppressed. A cutting process is not required. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal sheet bending method and apparatus suitable for forming a bent portion having no roundness at an end portion of an exterior sheet metal part.
[0002]
The present invention also relates to a press drawing apparatus that can form a rounded corner at a radius of curvature smaller than the plate thickness.
[0003]
[Prior art]
In exterior sheet metal parts such as an electronic device, a hook portion bent in an L shape may be formed at an end portion exposed to the outside. Such a hook part is used for hooking and using a counterpart part. Since the end portion where the hook portion is formed is exposed to the outside, it is processed so that the protruding corner portion is not rounded so that it is not known that there is a bend. For example, as shown in FIG. 6, the surface of the exterior sheet metal part 1 is a body surface 2, and a protruding plate portion protruding from the end surface (outside cutout) 3 is bent at a right angle to the back surface 4 side. The formed hook 5 may be formed. In this case, the bent surface 6 of the hook 5 is the same surface as the end surface 3, and the protruding corner portion 7 is not rounded and has a right-angle cross-sectional shape continuous to the ridge line portion 3 a on the surface side of the end surface 3.
[0004]
Here, even if the protruding plate portion protruding from the end surface 3 of the exterior sheet metal part 1 is simply bent, the hook 5 cannot be formed so that the protruding corner portion is not rounded. That is, as shown in FIG. 7, when the protruding plate portion 5A indicated by the imaginary line is bent at a right angle, the protruding corner portion 7A is rounded with a radius of curvature larger than the plate thickness t. As a result, the corner portions of the cut surfaces 3 b and 3 c are exposed on both sides of the formed hook 5.
[0005]
Therefore, conventionally, the following corners of the hook 5 are prevented from being rounded by the following molding methods 1 to 3.
[0006]
Method 1: A method comprising two steps of bending and shaving. In the bending step, as shown in FIG. 8 (a), the protrusion 5b protrudes so that the bending surface 5a is positioned outside the end surface 3 of the exterior sheet metal part 1. The plate portion 5A is bent at a right angle. Next, in the shaving process, as shown in FIG. 8B, the protruding plate portion 5 </ b> A protruding from the end surface 3 (the portion indicated by hatching) is scraped to form a hook 5.
[0007]
Method 2: An improved method of the above-mentioned method 1, which consists of three steps of bending, molding, and shaving. The protruding plate portion 5A is formed slightly longer, and the bending step is as shown in FIG. 9 (a). The protruding plate portion 5A is bent at a right angle so that the bent surface 5a is positioned outside the end surface 3. Next, in the molding process, as shown in FIG. 9B, the protruding plate portion 5A is compression-molded in the length direction from the tip surface 5c, and is thickened by the cutting allowance. In the next shaving process, as shown in FIG. 9C, the portion protruding from the end surface 3 is scraped off to form the hook 5.
[0008]
Method 3: This method consists of one step of squeezing bending. As shown in FIG. 10, a pressing is applied to the back side of the bent portion of the protruding plate portion 5A, and the protruding portion 5A is bent at a right angle in this state. Then, the sheet is ironed from the side of the bent surface 5a and molded.
[0009]
[Problems to be solved by the invention]
However, the conventional method has the following problems. In the above method 1, since the protruding portion is cut, the thickness of the formed hook is reduced, and the strength is reduced. Further, the cut surface may be exposed on both sides of the hook. Furthermore, since chips are produced, it becomes a cause of defects.
[0010]
On the other hand, in the above method 2, although the plate thickness is increased by the amount of cutting by compression molding, it is possible to prevent the strength of the formed hook from being lowered, but the production efficiency is lowered because the number of steps is increased by one. In addition, chipping is a cause of defects.
[0011]
On the other hand, although the above method 3 includes only one step, it is impossible to form a corner portion that is completely rounded. Moreover, the thickness of the formed hook part becomes thin, and strength falls. Furthermore, there is a problem that the tip surface of the hook portion is deformed.
[0012]
On the other hand, the shape of exterior parts such as electronic equipment formed by press drawing is determined from the design, so it may be inconvenient for the rounded shape that is obtained by press processing at the corner of the exterior part. is there. In other words, in ordinary drawing, the corner of the protruding corner is rounded with a radius of curvature greater than the thickness of the pressed product, so a corner with a radius of curvature smaller than the plate thickness is formed. Can not.
[0013]
In view of these points, the object of the present invention is to suppress an increase in the number of processes, suppress a decrease in strength of a formed bent portion (hook), and form a non-rounded corner portion, and a cutting process It is to propose a method and apparatus for bending a metal plate that does not require the use of a metal plate.
[0014]
Another object of the present invention is to propose a press drawing apparatus capable of forming a protruding corner portion with a radius of curvature smaller than the plate thickness.
[0015]
[Means for Solving the Problems]
In order to solve the above problems, the present invention is a metal plate bending method for bending a protruding plate portion protruding from an end face of a metal plate main body to a predetermined angle in a state where the metal plate cannot be rounded,
A bending step of bending the projecting plate portion at a smaller angle than a target angle at a position outside the end surface so that a cut surface formed between the end surface and the end surface is not exposed. When,
A compression molding step of pressing the outer surface of the curved plate portion to the end while compressing the curved plate portion in the length direction from the distal end surface of the curved plate portion with a press inside the bending root portion. It is characterized by.
[0016]
Here, as a compression molding apparatus used for the compression molding step in the above bending molding method,
A die having a work placement surface on which the presser is formed at the end;
A stripper that presses the metal plate body against the workpiece placement surface;
A movable punch for pushing the outer surface of the curved plate portion protruding from the sides of the die and the stripper to the end surface;
The thing of the structure provided with the die insert provided with the press surface which presses the said front end surface of the said curved plate part pushed in by the said movable punch in a length direction can be used.
[0017]
Next, the present invention is a press drawing apparatus for forming a metal molded product having a predetermined rounded corner portion,
With a rounded shape that targets a corner portion for forming the protruding corner portion of the metal molded product in the die,
A build-up portion for pressing the metal molded product material into the entering corner portion of the die is formed at a portion of the punch that corresponds to the back surface of the protruding corner portion of the metal molded product.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
A method for forming a sheet metal part to which the present invention is applied will be described below with reference to the drawings.
[0019]
(Method and apparatus for bending sheet metal parts)
FIG. 1 is an explanatory view showing a method of bending a sheet metal part to which the present invention is applied. The bending method of this example is a bending method in which a protruding plate portion protruding from the end face of a sheet metal part is bent at a predetermined angle without being rounded, and includes two steps of a bending step and a compression forming step. It is out. In the bending process, as shown in FIG. 1 (a), the protruding plate portion 12 having a constant width protruding from the end face 11 of the sheet metal part 10 is bent by an angle smaller than a target angle (in this example, a right angle). The curved plate portion 12A is assumed. Here, the bending base of the protruding plate portion 12 is positioned outside the end surface 11 so that the cut surfaces 13 and 14 formed between the protruding plate portion 12 and the end surface 11 are not exposed on both sides of the protruding plate portion 12 in a bent state. To. Further, the length of the protruding portion 12 is made longer than the length of the bent portion 12B finally obtained.
[0020]
In the next compression molding step, as shown in FIGS. 1B and 1C, a presser 15 as shown by an imaginary line is inserted into the curved portion 12a inside the curved plate portion 12A, and in this state, the curved plate portion While compressing 12A from its front end surface 12b in the length direction, the outer surface 12c of the curved plate portion 12A is pushed into the end surface 11 to form a bent portion 12B. Here, when pushing the outer surface 12c of the curved plate portion 12A to the end surface 11, it is necessary to securely hold the sheet metal part 10 from above and below so that the sheet metal product 10 does not escape. In addition, it is necessary to hold down the bending base portion of the curved plate portion 12A so that the surface (the surface of the sheet metal part) 10a does not leave a mark. Further, when the curved plate portion 12A is compressed in the length direction, it is necessary to prevent the meat from escaping in the width direction. Furthermore, the mold used for such compression molding needs to be free from gaps in the molded portion with a minimum of play, as in forging.
[0021]
According to the method of this example, after the protruding portion 12 is bent at a shallow angle to form the curved plate portion 12A, the press plate 15 is inserted to prevent escape of meat when the curved plate portion 12A is compressed, The curved plate portion 12A is compressed in the length direction and pushed to the end surface 11 so as to be perpendicular. As a result, the protruding corner portion 12d in the formed bent portion 12B is not rounded but becomes a right angle.
[0022]
Thus, according to the method of this example, it is possible to form the bent portion 12B in which the protruding corner portion is not rounded without increasing the number of steps. In addition, a bent portion can be formed with little reduction in wall thickness. Furthermore, since a cutting process is not required, the processing time can be shortened and no adverse effects caused by the generation of chips will occur.
[0023]
Next, an example of a compression molding apparatus for performing the compression molding step in the method of this example will be described. 2A and 2B are schematic configuration diagrams showing a compression molding apparatus, in which FIG. 2A shows a state where the sheet metal part 10 after the bending process is set, and FIG. 2B shows a state after compression molding.
[0024]
Referring to these drawings, the compression molding apparatus 20 of the present example includes a die 22 having a work placement surface 21 with a presser 15 formed at an end thereof, and a stripper 23, and is moved up and down. The sheet metal part 10 is pressed and fixed to the workpiece placement surface 21 by the stripper 23 that performs the above operation. Movable to push the outer surface 12c of the curved plate portion 12A after the bending process projecting from the end surface 11 of the sheet metal part 10 sandwiched between the die 22 and the stripper 23 to the end surface 11. A punch 24 is arranged. Further, a die insert 25 having a pressing surface 25a that is compressed in the length direction while sliding the tip surface 12b of the curved plate portion 12A pushed by the movable punch 24 is disposed.
[0025]
The die 22 and the die insert 25 are fixedly disposed on the upper surface of the backing plate 26. The movable punch 24 can be reciprocated left and right by a cam mechanism (not shown) or the like, and its vertical front end surface 24a is a pushing surface for pushing the outer surface 12a of the curved plate portion 12A, and a horizontal surface 24b extending continuously from the lower end edge thereof. However, it slides along the horizontal pressing surface 25a of the die insert 25.
[0026]
Here, the level | step difference of the workpiece | work mounting surface 21 of the die | dye 22 and the press surface 25a of the die insert 25 respond | corresponds to the length of the bending part 12B finally formed. Further, the vertical side surface 22a of the die 22 is set back more than the vertical side surface 23a of the stripper 23, and the set back amount corresponds to the thickness of the bent portion 12c to be finally formed. The movable punch 24 is movable to a position where its pushing surface 24 a comes into contact with the vertical side surface 23 a of the stripper 23.
[0027]
In the compression molding apparatus 20 having this configuration, the sheet metal part 10 is placed on the work placing surface 21 as shown in FIG. Thereafter, the stripper 23 is lowered, and the sheet metal part 10 is pressed against the workpiece placement surface 21 and fixed. Next, the movable punch 24 is slid to push the curved plate portion 12A in the lateral direction. The curved plate portion 12A is gradually bent to a large angle by being pushed by the pushing surface 24a of the movable punch 24. At the same time, the tip surface 12b of the curved plate portion 12A is pushed upward by the pressing surface 25a of the die insert 25 and gradually compressed in the length direction. As a result, the bending of the curved plate portion 12A proceeds while the meat is brought close to the bending root portion of the curved plate portion 12A. Therefore, at the end of the compression molding shown in FIG. 2B, the horizontal lower surface 23b of the stripper 23 defining the protruding corner portion 12d of the formed bent portion 12B and the vertical pressing surface 25a of the movable punch 25 are perpendicular to each other. Meat is pushed into the entering corner portion, and a bent portion 12B having a protruding corner portion 16a having a right-angled cross section without roundness is obtained. Further, the protruding plate portion 12 is longer than the finally obtained bent portion 12B and is compressed in the length direction in the compression molding process, so that the thickness of the formed bent portion 12B is not reduced and sufficient. Strength is given.
[0028]
In addition, the bending method of the sheet metal part of the present invention can be used to form a bent portion that is bent at an angle other than a right angle so that the protruding corner portion is not rounded. It can also be used for processing such as step bending of sheet metal parts.
[0029]
(Press drawing machine for sheet metal parts)
Next, a press drawing apparatus for forming a metal molded product having a predetermined rounded corner portion to which the present invention is applied will be described.
[0030]
For example, in the box-shaped press-drawn molded product 30 shown in FIG. 3A, as described above, the radius of curvature of the rounded corner portion is larger than the plate thickness. For this reason, it is impossible to form the rounded corner portion 31 having a radius of curvature R smaller than the plate thickness t as shown in FIG. 3B by press drawing.
[0031]
In order to form such a small rounded corner portion 31, as shown in FIG. 4A, the rounded corner portion 31 A obtained by normal press drawing is indicated by hatching. It is sufficient that the volume 32 can be added.
[0032]
In view of this point, the press drawing apparatus of the present example collects the meat corresponding to the volume 32 in the protruding corner portion 31A at the time of press drawing by applying a special shape to the press drawing mold. . In general, since the die side is a product appearance surface, a special shape is applied to the punch side.
[0033]
That is, as shown in FIG. 4 (b), in the press draw forming die 41 of the press draw forming apparatus 40 of this example, there is an entering corner portion 41a for forming the protruding corner portion 31 of the press draw formed product 30. The target is a rounded shape. Further, a built-up portion 42b for pushing a metal material into the entering corner portion 41a of the die 41 is formed at a portion of the tip surface portion 42a of the punch 42 for press drawing forming that corresponds to the back surface of the protruding corner portion 31. In this example, a trapezoidal shaped part 42b having a special shape protruding upward is formed.
[0034]
If the press drawing apparatus 40 having this configuration is used, a portion on the back surface side of the press drawn molded product 30 is pushed up by the build-up portion 42b of the punch 42 during drawing, and the material is pushed into the insufficient volume portion of the protruding corner portion 31. It is. As a result, the press-drawn molded product 30 having the protruding corner portion 31 having a shape corresponding to the entering corner portion 41a of the die 41 is obtained.
[0035]
The shape of the built-up portion 42b has a property that should be appropriately set according to the width, height, bending angle, and the like of the protruding corner portion of the press-formed product. An example of the cross-sectional shape of the built-up portion is shown in FIG.
[0036]
If the press drawing apparatus 40 of this example is used, the molded product provided with the target rounded corner part can be obtained.
[0037]
【The invention's effect】
As described above, in the method and apparatus for bending a sheet metal part according to the present invention, the bent portion is bent shallowly, and then the bent portion is pressed with the back side of the bent portion. Is compression-molded in the length and thickness directions. According to the method and apparatus of the present invention, it is possible to form a bent portion having a non-rounded corner portion without increasing the number of steps. Moreover, since the reduction | decrease in the plate | board thickness of a bending part can also be suppressed, it can also prevent that the intensity | strength of the said part falls. Furthermore, since a cutting process is not required, the processing time can be shortened, and adverse effects caused by chips can be avoided.
[0038]
Next, in the press drawing apparatus of the present invention, a built-up portion having a special shape is formed on the punch side, and the material is extruded to the protruding corner portion side of the molded product during press drawing. Therefore, according to the present invention, by appropriately setting the shape of the built-up portion, it is possible to easily obtain a molded product having a rounded protruding corner portion having a predetermined curvature radius.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a method of bending a sheet metal part to which the present invention is applied.
FIG. 2 is a schematic configuration diagram showing a compression molding apparatus to which the present invention is applied.
FIG. 3 is a perspective view and a partial cross-sectional view showing an example of a press-drawn product.
FIG. 4 is an explanatory view showing a drawing operation by a press drawing apparatus according to the present invention.
FIG. 5 is an explanatory diagram showing the shape of a built-up portion formed on a punch.
FIG. 6 is an explanatory view showing an example of an exterior sheet metal part on which a hook is formed.
FIG. 7 is an explanatory view showing a state in which an exterior sheet metal part is bent.
FIG. 8 is an explanatory view showing a conventional molding method.
FIG. 9 is an explanatory view showing a conventional molding method.
FIG. 10 is an explanatory view showing a conventional molding method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Sheet metal part 11 End surface 12 Protruding plate part 12a Bending base part 12b End surface 12c Outer surface 12d Outer corner part 12A Curved plate part 12B Bending part 15 Holding part 20 Compression molding apparatus 21 Workpiece mounting surface 22 Die 23 Stripper 24 Movable punch 25 Nesting die 25a Pressing surface 40 Press drawing apparatus 41 Die 41a Entering corner portion 42 Punch 42a Tip surface portion 42b Overlaying portion

Claims (3)

A metal plate bending method for bending a protruding plate portion protruding from an end surface of a metal plate main body to a predetermined angle in a state where the metal plate body cannot be rounded,
A bending step of bending the projecting plate portion at a smaller angle than a target angle at a position outside the end surface so that a cut surface formed between the end surface and the end surface is not exposed. When,
A compression molding step of pressing the outer surface to the end portion while compressing the curved plate portion in the length direction from the distal end surface in a state where a press is inserted inside the bending root portion of the curved plate portion,
A method of bending a metal plate including: A compression molding apparatus used for the compression molding step in the metal sheet bending method according to claim 1,
A die having a work placement surface on which the presser is formed at the end;
A stripper that presses the metal plate body against the workpiece placement surface;
A movable punch for pushing the outer surface of the curved plate portion protruding from the sides of the die and the stripper to the end surface;
A die insert provided with a pressing surface that presses the distal end surface of the curved plate portion pressed by the movable punch in the length direction;
A compression molding apparatus. A press drawing apparatus for forming a metal molded product having a predetermined rounded corner portion,
With a rounded shape that targets a corner portion for forming the protruding corner portion of the metal molded product in the die,
A press drawing apparatus in which a built-up portion for pressing a metal molded product material into the entering corner portion of the die is formed at a portion of the punch that corresponds to the back surface of the protruding corner portion of the metal molded product.

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