JP2008023566A - Press forming method for metallic can and forming apparatus therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a press forming apparatus where even in complicated working for the object to be worked such as folding and curved bending, its structure can be made simple and compact, and further, sufficient forming accuracy can be obtained. <P>SOLUTION: The press forming method for a metallic can includes sequentially operating: a first seat pressing step A where an annular projecting strip 3 is beforehand seat-pressed to the surface of a metallic sheet; a primary bending step B where the circumferential edge of the flat sheet 1a with the projecting strip formed by the primary seat pressing stage is bent to the lower part; a secondary bending step C where a part of the circumferential side wall part of the metallic can body 1b with the circumferential side wall part 4 formed by the primary bending step is left, and the whole circumferential tip part thereof is bent to the inside at a right angle as a tongue piece 5; a nose bending step D where the tongue piece of the metallic can body 1c with the tongue piece formed by the secondary bending step is bent to the inside at an acute angle; a third bending step E where the circumferential side wall part 4 of the metallic can body 1d with the acute-angled tongue piece formed by the nose bending step is curvedly bent together with the tongue piece 5; and a secondary seat pressing step F where the projecting strip 3 of the metallic can body 1e with the curved circumferential side wall part formed by the third bending step is seat-pressed in the vertically reversed direction so as to form the metallic can 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a press forming method of a metal can (metal can body or metal can lid) formed by pressing a metal thin plate and a forming apparatus thereof.

Conventionally, as a method and a press mold for forming a metal thin plate by pressing, the metal thin plate is previously formed into a flat top plate portion by a press machine, and from the peripheral edge of the formed top plate portion. A work material having a right-angle bent portion bent at a right angle downward is provided, and the work material is placed on a lower die having a pad, and the upper die is lowered to further surround the peripheral edge of the right-angle bent portion. There is a method of bending inside and a press mold thereof as Japanese Patent Laid-Open No. 9-323124 (see Patent Document 1, FIGS. 1 and 7).

Japanese Patent Laid-Open No. 9-323124 (see FIGS. 1 and 7)

Hereinafter, a conventional press molding method and a press mold will be described with reference to FIGS.
The press molding method and the press mold of Patent Document 1 are provided with a workpiece 20 having a right-angle bent portion 22 that is bent downward at a right angle from a peripheral edge of a flat top plate portion 21 in advance by a press machine. In addition, after placing the workpiece 20 on the lower mold 11 having the pad 14, the upper mold 12 is lowered and the peripheral edge of the right-angle bent portion 22 is provided on the inclined curved blade 16 provided on the lower mold 11. The bent portion 23 is further bent inward along the peripheral edge of the right-angle bent portion 22 to form a negative angle bent portion 23.

However, in this kind of press molding method and press mold, the pad that supports the top plate portion of the workpiece, the upper die, and the peripheral edge of the right-angle bent portion of the workpiece are aligned to form a negative corner bent portion. In the lower mold, there is always a large space between the top plate and the right-angle bent portion of the workpiece and the pad, and pressure is applied to the top plate and the right-angle bent portion of the workpiece during pressing. However, there is a problem that the predetermined accuracy cannot be improved.

Further, in this press molding method and press mold, it is not technically easy to fold the negative edge of the work piece or the peripheral edge of the negative turn part inside, and the work piece is folded at right angles. There was a problem that the curved portion could not be bent at all.

The present invention bends the peripheral edge of the flat plate 1a with the convex band formed by the primary counter pressing process A and the primary counter pressing process A in which the annular convex band 3 is pressed against the surface of the metal thin plate in advance. Bending the interior of the metal can 1b with the peripheral side wall 4 formed by the primary bending process B and the primary bending process 1b at a right angle with the entire peripheral tip as a tongue piece 5 while leaving a part of the peripheral side wall. Next bending step C, nose bending step D for bending the tongue of the metal can body 1c with the tongue formed by the second bending step acutely inward, and the sharp tongue formed by the nose bending step A third folding step E in which the peripheral side wall 4 of the metal can body 1d with a piece is bent in a curved shape together with the tongue piece 5, and a convex band of the metal can body 1e with a curved peripheral side wall portion formed by the third bending step. The secondary seat pressing process F in which the metal can 1 is formed by seating 3 in the upside down direction is sequentially operated. It is a press molding method of metal cans.

Further, a molding apparatus 11 for bending the distal end portion of the peripheral side wall 4 of the metal can 1b at a right angle to the inside includes a lower base 12 that can be vertically expanded and contracted on the die 8 and a split mold 14 that can be slid right and left on the lower base. And an upper mold 10 provided with an upper base 17, a fixed frame 18 under the upper base, and a slidable expansion / contraction split mold 19 below the fixed frame, and a left / right / up / down movement of the split mold A movable split type expansion mechanism that expands the split mold and follows the outer shape of the fixed split mold, a fixed frame holding mechanism that allows the inner wall of the fixed frame to run along the upper outer surface of the peripheral side wall of the metal can body, and an upper mold expansion and contraction A mechanism that shrinks the mold and bends the tip of the entire circumference of the metal can body to the inside at a substantially right angle, a stretchable split type expansion mechanism that expands the stretchable split mold after being bent at a right angle, and a movable split mold by raising the lower base The moving split type contraction mechanism that contracts is sequentially operated.

Furthermore, the molding device 24 for bending the peripheral side wall 4 of the metal can 1d into a curved shape includes a folding lower base 25 on the pedestal 21 that can be expanded and contracted vertically and a slidable folding on the left and right sides on the folding lower base. A folding lower mold 22 provided with a dividing mold 27 and a folding upper mold 23 provided with a folding upper base 30 and a folding fixing frame 31 under the folding upper base. Folding split type expansion mechanism that expands the left and right, upper and lower folding split type for folding along the outer shape of the fixed split type for folding, and the peripheral side wall of the metal can body is folded inward. A curved peripheral side wall forming mechanism for forming a curved peripheral side wall portion along the outer surface of the curved split mold and the outer surface of the upper base for bending and the inner surface of the fixing frame for bending, and the right The upper and lower folding movable split molds are contracted to sequentially operate the folding lower base returning mechanism for returning the folding lower base.

The present invention solves the conventional problems, and even if complicated processing such as folding or bending a workpiece, the structure can be simplified and the size can be reduced, and sufficient molding accuracy can be obtained. be able to.

Embodiments of the present invention will be described below with reference to the drawings.
A metal can formed by sequentially pressing a single metal thin plate indicates a metal can body or a metal can lid. In the embodiment of the present invention, a metal can lid will be described in particular.
As shown in FIG. 1, the metal can 1 is formed into a rectangular flat plate 1a having four large arc-shaped corners 2, 2, 2, 2 as shown in FIG. After cutting, as shown in FIG. 2, an annular convex band 3 is formed on the surface of the flat plate 1 a in the primary pressing process A.

Next, as shown in FIG. 3, the peripheral edge of the flat plate 1 a with the convex band 3 formed in the primary seat pushing step A is bent downward at a right angle, and the peripheral side wall portion 4 formed by bending is provided. A primary bending step B for forming the box-shaped metal can body 1b, and a part of the peripheral side wall portion 4 of the metal can body 1b formed in the primary bending step, with the entire peripheral tip portion substantially inward. A secondary folding step C for forming a metal can body 1c with a tongue piece provided with a tongue piece 5 by bending at a right angle, and a metal can body 1c with a tongue piece formed in this secondary bending step A nose bending step D in which the tongue piece 5 is further bent acutely toward the inside of the peripheral side wall portion 4;

The metal can body 1d formed by this nasal bending process is overlapped with the inner lower end of the remaining peripheral side wall portion 4 so as to be along the tongue piece 5, and the remaining peripheral side wall portion 4 is bent in a curved shape inward. A tertiary bending step E for forming the metal can body 1e with the curved peripheral side wall portion 6 by bending, and an annular convex band of the metal can body 1e with the curved peripheral side wall portion formed by the tertiary bending step. 3 is pressed in the upside down direction to form a ring-shaped concave band 7 and the secondary seat pressing step F for forming the metal can 1 which is a metal can lid body is sequentially formed.

As shown in FIG. 1, the single metal thin plate used in the primary counter-pressing step A is cut into a horizontally long rectangular plate 1 a having large arc-shaped corners 2 in four directions.
The shape of the flat plate 1a is not particularly limited, and the shape of the flat plate 1a is determined according to the shape of the metal can to be formed.

As shown in FIG. 3 (a), the primary seat-pressing process A simply forms an annular convex band 3 on the surface of the flat plate 1a, and the convex band formed in the primary seat-pressing process. As shown in FIG. 2, the flat plate 1 a with 3 is provided with a convex band 3 on the surface, thereby preventing deformation of the surface of the flat plate and increasing the deformation strength as compared with a normal flat plate.

In the primary bending step B, as shown in FIG. 3B, a box-shaped metal can body in which the entire peripheral edge of the flat plate 1a is bent downward at a right angle and this bent portion is used as the peripheral side wall portion 4. 1b is formed.

As shown in FIG. 3 (c), the secondary bending step C is performed by operating a secondary bending apparatus 11 including a lower die 9 and an upper die 10 attached on the die 8, and a metal can body 1b. A metal can body 1c with a tongue piece having a piece obtained by bending a peripheral tip portion inwardly at a substantially right angle while leaving a part of the peripheral side wall portion 4 as a tongue piece 5 is formed.

As shown in FIGS. 5 and 6, the lower mold 9 of the secondary bending device 11 supports the lower base 12 of the lower mold on the die 8 via base expansion and contraction springs 13, 13. A split mold 14 is provided at the center of 12 along the shape of the metal can 1b.

As shown in FIG. 5, the split mold 14 includes fixed split molds 14a, 14a, 14a, 14a on the long diameter side of four corners, movable split molds 14b, 14b on the left and right long diameter sides, and upper and lower short molds. It is composed of movable division molds 14c and 14c on the radial side, and the outer shape thereof is provided with a groove for bending the distal end portion of the peripheral side wall portion of the metal can body 1b and inserting the inner distal end of a telescopic division mold described later.

The left and right, upper and lower movable split dies 14b, 14b, 14c, and 14c extend along the cam portion 15 of the die 8 to be described later, along the outer shape of the fixed split mold 14a, and the left and right, upper and lower movable split dies 14b and 14c. The left and right and upper and lower moving split molds are shrunk by attached moving split springs (not shown).

The cam portion 15 of the die 8 protrudes toward the center of the die and is integrated with the die. The cam portion 15 is connected to the left and right, upper and lower movable split dies 14b, 14b, 14c, and 14c. The upper and lower movable division types are slidable.

As shown in FIG. 4 or FIG. 6, the upper mold 10 of the secondary bending apparatus 11 is provided with an upper base 17 having a recess 16 whose center is shaped along the upper surface of the metal can body 1b. On the lower side, a fixed frame 18 is provided around the outer periphery of the concave portion, and on the lower side of the fixed frame, expansion / contraction split dies 19, 19, 19, 19 are provided that extend inward and outward.

As shown in FIG. 4, the stretchable split mold 19 is divided into four parts, which are coupled to each other by stretchable split type springs 20, 20, 20, 20, and are normally expanded. Each stretchable split mold 19 is contracted when the outer sloped side of the stretchable split mold 19 slides down along the tilted side.

As shown in FIG. 6, the secondary bending apparatus 11 places the metal can body 1 b as a workpiece on the divided mold 14 with respect to the lower mold 9 attached on the die 8, and then the upper mold 10. And the upper die 10 is lowered.

The operation of the secondary bending device 11 is performed by lowering the upper die 10 (FIG. 6A) as shown in FIGS. 6A to 6C as the upper die 10 is lowered and raised. Lower the base 12 against the base expansion and contraction springs 13 and 13 (FIG. 6B), and expand the left and right and upper and lower movable split dies 14b, 14b, 14c and 14c,

Furthermore, a movable split type expansion mechanism that extends along the outer shape of the fixed split mold 14a, and a fixed frame holding mechanism that expands the movable split mold and extends the inner wall of the fixed frame 18 along the upper outer surface of the peripheral side wall 4 of the metal can body 1b. And a mechanism that shrinks the upper expansion / contraction split mold 19 to bend the entire peripheral tip of the metal can 1b inward at a substantially right angle; a telescopic split expansion mechanism that expands the expansion / contraction split mold after being bent at a right angle; After expanding the split mold, the lower base is raised and the movable split type contraction mechanism that shrinks the movable split mold is sequentially performed. All of these mechanisms are compact and easy to perform complicated operations only at one press. Will be done.

In the nasal bending process D, as shown in FIG. 3D, the tongue piece 5 that is bent at a substantially right angle of the metal can body 1 c is further bent at an acute angle toward the inside of the peripheral side wall portion 4.

As shown in FIG. 9, the third bending process E is performed by operating a third bending apparatus 24 including a lower bending mold 22 and a bending upper mold 23 that are mounted on a pedestal 21. The tongue pieces 5 of 1c are overlapped so as to be along the inner lower end of the peripheral side wall part 4, and are bent into a curved shape with the peripheral side wall part 4 facing inward.

The tertiary folding device 24 includes a folding lower mold 22 on a pedestal 21 and a folding upper mold 23 covering the folding lower mold. The folding lower mold 22 is shown in FIG. As shown, the folding lower base 25 is supported on the pedestal 21 through the folding lower base contracting springs 26, 26, and is bent along the shape of the metal can 1c at the center of the folding lower base. A split mold 27 is provided.

As shown in FIG. 8, the folding split mold 27 is composed of four fixed corner split molds 27 a, 27 a, 27 a, 27 a on the long diameter side and left and right long split side moving splits. It consists of dies 27b and 27b and upper and lower short-distance side bending dividing molds 27c and 27c, and is provided in an outer shape that can bend the peripheral side wall of the metal can 1c.

The left and right and upper and lower folding movable dividing dies 27b and 27c extend along the folding cam portion 28 of the base 21, and follow the outer shape of the folding fixed dividing mold 27a, and also for the left and right and upper and lower folding dies. The left and right and upper and lower folding moving split molds are contracted by folding splitting springs (not shown) attached to the movable split molds 27b and 27c.

As shown in FIG. 7 or FIG. 9, the upper mold 23 for tertiary folding of the apparatus for tertiary bending is a folding upper provided with a folding recess 29 whose center is shaped along the upper surface of the metal can 1c. A base 30 is provided, and a bending fixing frame 31 is provided around the outer periphery of the bending concave portion on the lower side of the bending upper base. The inner side of the bending fixing frame 31 is formed in a curved shape, and extends along the outer side of the bending concave portion 29 of the upper base for bending.

As shown in FIG. 9, the tertiary bending device 24 is configured such that the metal can 1d as a workpiece is placed on the folding split mold 27 with respect to the lower folding mold 22 attached on the pedestal 21. After (a) in FIG. 9 is mounted, an upper mold 23 for tertiary bending is attached, and the upper mold for tertiary bending is lowered.

The protrusion 32 at the lower end of the bending fixing frame 31 pushes down the lower folding base 25 due to the lowering of the upper mold for the tertiary bending, and the left and right and upper and lower bendings are made along the bending cam portion 28 of the base 21. A split split type expansion mechanism for expanding the movable split molds 27b and 27c for extending along the outer shape of the fixed split mold for folding 27a;

Further, the inner side of the peripheral side wall portion 4 of the metal can body 1d is along the outer surface of the folding split mold 27, and the outer side is along the inner surfaces of the upper base 30 for bending and the fixing frame 31 for bending. The bent lower base return for returning the bent lower base 25 by contracting the bent peripheral side wall forming mechanism for forming the bent peripheral side wall 6 and the right and upper bending movable split dies 27b and 27c. The mechanisms are sequentially performed, and all of the mechanisms can easily perform complicated operations only at one press.

In the secondary buckling step F, as shown in FIG. 3 (f), the annular convex band 3 of the metal can 1e is seated in the upside down direction to perform desired molding, and the annular concave band 7 is formed. The metal can 1 that is the metal can lid body can be processed.

The metal can body 1 which is a metal can lid body formed in this manner is formed by forming the peripheral side wall portion into the curved peripheral side wall portion 6 and bending the tip end portion of the peripheral side wall portion inward. When covering the can body with a metal can body that is a metal can lid, the tip is rounded, so the tip is sharp and does not damage the user's finger. The curved side wall portion of the metal can body is easy to enter the mouth and, after entering, easily closes.

Although the embodiments considered to be representative of the present invention have been described above, the present invention is not necessarily limited only to the structures of these embodiments, and the metal can body can be formed as described above. The present invention has the above-described constituent requirements, can achieve the object of the present invention, and can be appropriately modified and implemented within the scope of the effects of the present invention.

The top view which shows the metal thin plate of this invention Example. The top view which shows the flat plate of this invention Example. Explanatory drawing which shows the shaping | molding process of this invention Example. The top view which shows the lower mold | type of the secondary bending apparatus of this invention Example. The top view which shows the upper mold | type of the secondary bending apparatus of this invention Example. Explanatory drawing which shows the operation state of the secondary bending apparatus of this invention Example. The top view which shows the lower mold | type of the tertiary bending apparatus of an Example of this invention. The top view which shows the upper mold | type of the tertiary bending apparatus of this invention Example. Explanatory drawing which shows the operation state of the tertiary bending apparatus of this invention Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Metal can 2 ... Metal thin plate corner 3 ... Convex band 4 ... Peripheral side wall part 5 ... Tongue piece 6 ... Curved peripheral side wall part 7 ... Concave belt 8 ... Die 9 ... Lower mold | type 10 ... Upper mold | type 11 ... Two Next folding device 12 ... Lower base 13 ... Base expansion / contraction spring 14 ... Split mold 14a ... Fixed split mold 14b ... Left and right movable split mold 14c ... Up and down movable split mold 15 ... Cam part 16 ... Recess 17 ... Upper base 18 ... Fixed frame 19 ... Stretchable split mold 20 ... Stretchable split mold spring 21 ... Base 22 ... Bending lower mold 23 ... Bending upper mold 24 ... Third folding apparatus 25 ... Bending lower base 26 ... Bending Lower base telescopic spring 27 ... Folding split mold 27a ... Folding fixed split mold 27b ... Left and right folding moving split mold 27c ... Up / down folding moving split mold 28 ... Folding cam part 29 ... Bending Recess 30 ... Bending upper base 31 ... Bending frame 32 ... Projection A ... Primary seat pusher B ... primary folding step C ... secondary folding step D ... nose piece Step E ... tertiary folding step F ... secondary seat pressing step

Claims (3)

The method of forming a metal can by pressing one sheet of metal sheet includes a primary sheet pressing step (A) in which an annular convex band (3) is previously pressed against the surface of the metal sheet, and a primary sheet pressing. A primary bending step (B) of bending the peripheral edge of the flat plate (1a) with a convex band formed by the process downward, and a metal can body with a peripheral side wall (4) formed by the primary bending step ( 1b) a second bending step (C) in which a part of the peripheral side wall portion is left to be bent inward at a right angle with the entire peripheral tip portion as a tongue piece (5), and with a tongue piece formed by the secondary bending step A nasal bending step (D) of bending the tongue of the metal can body (1c) acutely inward, and a peripheral side wall portion (4) of the metal can body (1d) with an acute tongue formed by the nasal bending step A third bending step (E) of bending the tongue together with the tongue piece (5), and a curved periphery formed by the third bending step It is characterized by sequentially operating a secondary pressing process (F) in which the convex band (3) of the metal can body (1e) with a wall is pressed in the upside down direction to form the metal can (1). The metal can press forming method. The forming device (11) for bending the distal end of the peripheral side wall portion (4) of the metal can body (1b) to the inside at a right angle includes a lower base (12) that can be vertically expanded and contracted on the die (8) and a left and right slide on the lower base. A lower mold (9) having a movable split mold (14), an upper base (17), a fixed frame (18) under the upper base, and a telescopic split mold (19) that is slidable to the left and right under the fixed frame; An upper mold (10) provided with a movable split type expansion mechanism that expands the left and right, upper and lower movable split molds of the split mold and follows the outer shape of the fixed split mold, and the upper part of the peripheral side wall portion of the metal can body A fixed frame holding mechanism that keeps the inner wall of the fixed frame along the outer surface, a mechanism that retracts the upper expansion / contraction split mold and folds the entire front end of the metal can body inward at a substantially right angle, and a folding / expanding split after bending at a right angle Expansion and contraction type expansion mechanism that expands the mold, and moving division type yielding that raises the lower base and contracts the movement division type Molding apparatus, characterized in that to sequentially operate a mechanism. The forming device (24) for bending the peripheral side wall portion (4) of the metal can body (1d) into a curved shape includes a lower base (25) for folding up and down on the base (21) and a lower base for bending. A folding lower mold (22) having a left and right slidable folding mold (27), a folding upper base (30), and a folding fixing frame (31 below the folding upper base). And a folding upper mold (23) provided with a folding upper mold (23) to expand the left and right and upper and lower folding movable dividing molds so that they follow the outer shape of the fixed folding mold for folding. With the split type expansion mechanism, the outer side surface of the split type for folding along the peripheral side wall of the metal can body, along the inner surface of the upper base for folding and the fixed frame for folding, A curved peripheral side wall forming mechanism for forming the curved peripheral side wall, and a folding lower base returning mechanism for retracting the lower folding base by shrinking the right and the upper and lower folding movable dividing molds Molding apparatus, characterized in that is sequentially operated.

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