JPH0576968A - Device for forming square can - Google Patents

Abstract

PURPOSE:To completely eliminate defective work due to the deviation of inward bent line of a corner wall by correctly bending the corner wall along its diagonal line, with respect to a square shaped can which is provided with side walls facing front and rear and left and right in continuation of a bottom wall and whose each square corner wall between the two side wall is bent inwardly in a triangle shape along the inner face of an adjacent side wall. CONSTITUTION:On both ends of a first bending die 13 by which one pair of facing side walls 4 is bent ahead of the other pair, a regulating part 21 is provided by which corner walls 10 are bent concurrently with the side walls 4 and their outer faces are caught. A pressurizing body 22, by which the inward bending of the corner walls 10 is prompted, is retractably supported on this regulating part 21 and advanced and energized by a spring 23 in the direction of the inward bending of the corner walls 10. By the pressurizing body 22, the corner walls 10 are pressed to the inward bending direction and their buckling and deformation are prevented when the remaining corner walls are bent concurrently with the other pair of side walls.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forming device for a rectangular can formed only by bending.

[0002]

2. Description of the Related Art An apparatus for forming a rectangular can of this type is known, for example, from Japanese Patent Publication No. 61-37019. Where,
A rectangular can is formed through a step of forming a punch blank, a step of forming a temporary folding line on the punch blank, a step of folding up the peripheral side wall of the can, and a step of curling the edge of the peripheral side wall. In other words, a square can is completed only after going through four types of processing equipment.

The Applicant has simplified the above-mentioned processing steps,
An improved manufacturing apparatus that can complete a square can in two steps was previously proposed (Japanese Patent Application No. 2-268763). In this method, a temporary folding line is formed at the same time as blanking is performed, the peripheral side wall of the can is folded, and then curling or edging is performed all at once.

[0004]

In the rectangular can to which the present invention is directed, a rectangular corner wall between adjacent peripheral side walls is folded into a triangular shape on the inner surface of one peripheral side wall. There was a problem in that the wall could not be bent reliably. In a rectangular rectangular can, for example, after folding up the short side portion of the peripheral side wall, folding up the long side portion of the peripheral side wall,
Using this folding operation, the corner wall is folded inward along its diagonal line so that it runs along the inner surface of the long side.However, since the corner wall is not bent directly with a mold, the inner bent line is It is easy to shift. For this reason, processing defects such as wrinkles occurring at the corners folded in a triangular shape and partial bending of the bending line between the corner wall and the long side portion or the short side portion have frequently occurred. By the way, in the previous proposal, by providing a reinforcing portion along the outer edge of the corner wall and increasing the buckling strength of the outer edge, the inner polygonal line is made to follow the diagonal line.
Even this may still cause the above-mentioned processing failure, which has been an obstacle in reducing the manufacturing cost of the rectangular can.

An object of the present invention is to improve the productivity and reduce the manufacturing cost of this type of rectangular can by making it possible to accurately bend the corner wall on a diagonal line and to almost completely eliminate defective products. It is in.

[0006]

The molding apparatus of the present invention comprises:
Having a folding die 16 and a pressing die 12 for sandwiching and fixing the unfolding blank 9 from the upper and lower surfaces, a pair of side walls 4 facing each other by moving relatively close to the pressing die 12 and both ends of this side wall 4. Having a first bending die 13 for bending the corner wall 10 along the outer side surface of the folding die 16 so that the corner wall 10 moves relatively close to the pressing die 12 and the remaining pair of side walls 3 adjacent to the side wall 4 is provided. Having a second bending die 14 for folding the corner wall 1 along both sides of the first bending die 13.
The restriction member 21 that receives the outer surface of 0 is provided, and the pressing member 2 that promotes inward bending of the corner wall 10 is provided in the restriction member 21.
2 is supported so that it can be retracted and retracted, and the spring 23 urges the corner wall 10 to advance in the direction of inward bending. Specifically, the bending line of the first bending die 13 is used as the reference line Q,
The contact portion of the pressing body 22 with the corner wall 10 and the bottom wall 2 of the corner wall 10
Assuming an action part line P connecting the base end of the diagonal line on the side, the reference line Q
It is a requirement that the angle θ sandwiched by the action line P is set within the range of 15 to 30 °.

[0007]

When the corner wall 10 is folded inward by the second bending die 14 using the folding operation of the remaining pair of side walls 3, the side wall 4 and the corner wall 10 folded by the first bending die 13 are folded. The side polygonal line of the is correctly defined by the folding mold 16, but
The side fold lines of the remaining pair of the side wall 3 and the corner wall 10 which are folded up by the bending die 14 of FIG. 3 do not define anything, and this causes the position of the inner fold line to deviate from the diagonal line. Therefore, if the pressing body 22 is provided on the restriction portion 21 and the bending of the side bent line of the latter is assisted by the urging force,
It is possible to bend each side polygonal line evenly, and as a result, it is possible to position the inner polygonal line at the correct position on the diagonal line.

[0008]

According to the present invention, the pressing member 22 is urged to move forward by the springs 23 to the regulating portions 21 at both ends of the first bending die 13.
And the second set of side walls 3 is folded up by the second bending die 14, the corner wall 10 is pushed inward by the pressing body 22 so that the remaining side wall 3 and the corner wall 10 are I made it possible to bend the side polygonal line properly. Thereby, the inner fold line of the corner wall 10 can be positioned at the center position of the pair of side part fold lines, that is, on the diagonal line, and the folding can be appropriately performed.
It has become possible to reduce the manufacturing cost by stably molding a rectangular can with good finish inside and outside the corner.

[0009]

1 to 9 show an embodiment of the present invention. FIG. 8 shows an example of a rectangular can obtained by the device of the present invention. This rectangular can 1 is used as a can of sweets or a packaging box for dried foods, and front and rear side walls 3 and left and right side walls 4 are erected from each side of a horizontally long rectangular bottom wall 2, and the front and rear side walls 3 are provided. With the corner portion 5 folded along the inner surface of the side wall and the edge-folded side portion 6 (see FIG. 9) of the front and rear side walls 3 which sandwich and fix the corner portion 5, the adjacent side walls 3 and 4 are prevented from falling outward from each other. It has a structure to be retained. Edge folding side portions 7 are also formed on the opening side portions of the left and right side walls 4.

In FIG. 7, the rectangular can 1 is formed by using a plated steel plate having a thickness of 0.2 mm as a raw material to form the expansion blank 9 shown in FIG. 7A, and sandwiching and fixing the expansion blank 9 at a bending position. After that, the step of bending the left and right side walls 4 shown in FIG. 7B, the step of bending the front and rear side walls 3 and the corners 5 shown in FIG. 7C, and the edge fold side portion 6
-It is molded through the process of bending 7.

The expansion blank 9 is formed by punching out a standard length steel plate or a coil plate and simultaneously bending it. Specifically, the bottom wall 2, the front, rear, left and right side walls 3 and 4 continuous with each side of the bottom wall 2, and the corner wall 10 provided between the adjacent peripheral side walls have a sheet shape that is substantially similar to the bottom wall 2 as a whole. Formed on the outer edges of the front and rear side walls 3 and the left and right side walls 4,
Each up. The outer corners of each corner wall 10 are cut into a chamfer. When the corner wall 10 is folded to form the corner portion 5, the cutout portion prevents the tip from being sharply pointed, and further ensures that the fold line is correctly formed along the diagonal line.

The unfolded blank 9 is subjected to a bending process one after another in the subsequent steps, and this series of bending processes is continuously performed by one molding apparatus. 4 to 6, the forming device is configured as a multi-stage pressing device, and includes a blank guide 11 for positioning the expansion blank 9, an upper mold provided above the expansion blank 9, and a permanent expansion in cooperation with the upper mold. A pressing die 12 for sandwiching and fixing the blank 9, a first bending die 13 for folding up and operating the left and right side walls 4, a second bending die 14 for folding up and operating the front and rear side walls 3, and a lowering limit of the pressing die 12. The lower limit stopper 15 and the like are provided.

The upper mold includes a lower folding mold 16 and an edge folding side portion 6.
An edge folding mold 17 for bending 7 toward the bottom wall 2 is used, and the bending work is sequentially performed by moving the entire structure downward. In addition, the edge folding mold 17 is
It is further lowered to bend the edge folding side portions 6 and 7.

The presser die 12 is supported by a lift shaft 19 so as to be able to move up and down.
A second bending die 14 for use is supported via a shaft 20 so as to be swingable upward only. As shown in FIG. 1, the first bending die 13 is arranged in a machine frame (not shown), and its front-rear length is set to the dimension of the left and right side walls 4 plus the lengths of both corner walls 10. There is. A restricting portion 21 that holds each corner wall 10 from the outer surface and restrains the bulging to the outer surface is provided at a portion protruding from the left and right side walls 4 to the front and rear.

As shown in FIGS. 2 and 3, the regulating portion 21
A pressing body 22 for urging the inner wall of the corner wall 10 to be bent is provided in a retractable manner, and a spring 23 urges the pressing body 22 to move toward the inner wall of the corner wall 10. The pressing body 22 has a pressing piece 24 made of a metal block whose tip is pointed in a triangular shape, and as shown in FIG. 2, the angle θ between the action line P passing through the ridge and the reference line Q is set to 15 °. .. The reference line Q is a bending line of the left and right side walls 4 by the first bending die 13, and the action portion line P is a diagonal base end of the corner wall 10 on the bottom wall 2 side and the corner wall 1 of the pressing piece 24.
It is an imaginary straight line connecting the contact portion with 0. In FIG.
Reference numeral 25 denotes a roller for operating the second bending die 14 to stand upright, which is fixedly supported by a machine frame (not shown) so as to be rotatable only.

The molding apparatus is in a standby state in which the presser die 12 is lifted and the upper die is positioned above the presser die 12 so as to be in a standby state. In this state, the blank guide 11 of the unfolding blank 9 is guided to the blank guide 11. The loading and the taking out of the rectangular can 1 that has been molded are performed. When the developing blank 9 is loaded into the blank guide 11 in this state and the upper die is lowered, the portion corresponding to the bottom wall 2 is sandwiched and fixed between the folding die 16 and the pressing die 12 from above and below. At this time, the folding mold 16 expands in all directions as shown by an imaginary line to have the same shape as the bottom wall 2. This is to facilitate mold release after can formation.

When the upper die is further lowered in this state,
As shown in FIG. 5, the presser die 12 moves together and moves downward, the portions corresponding to the left and right side walls 4 of the unfolding blank 9 contact the first bending die 13 and are bent along the outer surface of the folding die 16. .. At this time, the corner walls 10 located at the front and rear ends of the left and right side walls 4
Also bends continuously on the left and right side walls 4 (see FIG. 7).
(See (b)). When the left and right side walls 4 are completely upright,
The edge folding side portion 7 is inserted between the upper and lower sides of the folding die 16 and the edge folding die 17. At this time, the pressing body 22 retreats into the inside of the regulation portion 21 against the spring 23.

When the upper die is further lowered, as shown in FIG. 6, the second bending die 14 is brought into contact with the roller 25 to perform an upright operation, and the portions corresponding to the front and rear side walls 3 of the developing blank 9 are bent upward. .. At this time, the first bending die 13 holds the left and right side walls 4 between it and the folding die 16,
The restriction portions 21 at the front and rear ends hold down the outer surface of the bent corner wall 10 and hold it to restrict outward bulging deformation. Therefore, the corner wall 1 that receives the bending force by the second bending die 14
No. 0 cannot bend outward, but bends along the inner surface of the front and rear side walls 3 as shown in FIG. 7C.

During this folding process, a buckling load acts on the corner wall 10 and is further pushed inward by the pressing body 22 provided on the regulating portion 21. Therefore, the front and rear side walls 3
And the side wall 4 between the left and right side walls 4 and the corner wall 1.
It can be surely bent like the polygonal line between 0 and. By properly bending the pair of side bent lines in this way, an inner bent line can be correctly formed at an intermediate position between the two bent lines, that is, on a diagonal line of the corner wall 10, and the shape and folding position of the corner portion 5 can be optimized. Therefore, it has occurred frequently in the conventional device. Wrinkles on the inner and outer surfaces of the corner portion 5, the front and rear side walls 3
It is possible to eliminate machining defects such as ridges on both ends of the. By the way, the angle θ between the action line P and the reference line Q is 1
If the angle is less than 5 °, the fold line portion passes through the outer surface of the pressing body 22 before the side line fold line between the corner wall 10 and the front and rear side walls 3 is sufficiently formed, and the side line fold line is reliably formed. become unable. Further, when the angle θ exceeds 30 °, the pressing force by the pressing body 22 becomes effective only after the pair of side part broken lines are bent unevenly, and thus the side part broken line cannot be reliably formed also in this case. ..

The presser die 12 contacts the lower limit stopper 15,
In the state where the front and rear side walls 3 are completely erected, as shown in FIG. 9, a triangular corner portion 5 is formed along the inner surface thereof, and the upper edge of the corner portion 5 faces the bending base end of the edge folding side portion 6. .. Edge folding type 1
7 further descends from the above state, and the front, rear, left and right side walls 3,
Bend the edge fold sides 6 and 7 of 4 along the inner surface of the wall. As a result, in the front and rear side walls 3, the corner portions 5 are sandwiched and fixed by the edge folding side portions 6, and the adjacent wall surfaces are connected and fixed so as not to fall outward. After that, the upper die and the pressing die 12 are raised to return to the standby state, and the completed rectangular can 1 is taken out.

FIG. 10 shows a modification of the pressing body 22. In this case, the pressing piece 24 is formed in a hemispherical shape, and this is applied to the acting portion line P.
3 were arranged along the above to form the pressing body 22. Each pressing piece 24
The spring 23 urged the advance individually. In this way, the pressing body 22 can be formed by being divided into a plurality of pressing pieces 24, and when the height of the front and rear side walls 3 and 4 is small,
Only one pressing piece 24 may be provided.

In addition to the above, the edge-folded side portions 6 and 7 may be entirely formed as an inner curl. In this case, a curl groove that opens downward is formed in the edge folding die 17. Since the corner portion 5 is folded along the side wall that is bent in a later step, it can be arranged along the left and right side walls 4 as necessary. Any one of the upper mold and the lower mold may be used as long as one or both of them cooperate with each other, and a driving form other than the embodiment may be adopted.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part of a molding apparatus.

FIG. 2 is a side view of the inside of a bending die showing a pressing body and its peripheral structure.

3 is a cross-sectional view taken along the line AA in FIG.

FIG. 4 is a front view showing a schematic structure of a molding apparatus.

FIG. 5 is a front view showing an operating state of the molding apparatus.

FIG. 6 is a side view showing an operating state of the molding apparatus.

FIG. 7 is a perspective view showing a process of forming a rectangular can.

FIG. 8 is a perspective view of a rectangular can.

9 is a view on arrow B in FIG.

FIG. 10 is a side view of an essential part showing another embodiment of the pressing body.

[Explanation of symbols]

 1 Square Can 2 Bottom Wall 3 Front and Back Side Walls 4 Left and Right Side Walls 5 Corners 9 Deployment Blank 10 Corner Wall 12 Presser Type 13 First Bending Die 14 Second Bending Die 16 Folding Type 21 Restriction Part 22 Pressing Body 23 Spring

Claims (2)

[Claims] 1. A quadrangular bottom wall 2, two sets of side walls 3 and 4 folded from the bottom wall 2 and facing each other, and a corner portion 5 folded along one inner surface of both side walls 3 and 4. And a pressing die 12 for sandwiching and fixing the expansion blank 9 from the upper and lower surfaces, and a relatively close movement to the pressing die 12 to face it. A set of side walls 4 and corner walls 10 at both ends of the side walls 4 are folded into a folding mold 16
Has a first bending die 13 that bends along the outer side surface of the
Has a second bending die 14 that bends the remaining set of side walls 3 adjacent to each other along a folding die 16, and a regulation portion 21 that receives the outer surface of the corner wall 10 is provided at both ends of the first bending die 13. In addition, a pressing device 22 that promotes inward bending of the corner wall 10 is supported by the restricting portion 21 so that the pressing member 22 can be retracted and retracted, and a spring 23 biases the pressing member 22 to advance in the inward bending direction of the corner wall 10. 2. The contact portion of the pressing body 22 with the corner wall 10 and the corner wall 1 with the bending line of the first bending die 13 as a reference line Q.
Assuming an action portion line P connecting the diagonal base end on the bottom wall 2 side of 0, the angle θ between the reference line Q and the action portion line P is 15 to 30 °.
The apparatus for forming a rectangular can according to claim 1, wherein the setting is made within the range.