JP2003048027A - Method for forming laminated aluminum foil container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foil forming machine and a press working method in which forming limit is improved using a sure and simple device and in which no or very little wrinkles are generated in a flange part. SOLUTION: In the entire press forming process of a laminated aluminum foil for which a resin film is laminated on one or both sides of an aluminum foil, a wrinkle pressure pad surface pressure is controlled in the manner that a punching load becomes 50-95% of the breaking load of the laminated foil in the initial stage of forming and that, in the latter stage of forming, the pressure is reduced to the limit at which wrinkles are generated, thus, the press forming is performed while the ratio of the vertical surface pressure of a breaking risk area over the breaking strength of the laminated aluminum foil is constantly maintained nearly at a specific value between 0.15 and 0.50, as the characteristic of the method. The invention includes the device for this method as well as formed products of the laminated aluminum foil manufactured by this method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite material such as an aluminum foil and a resin sheet or film (in the present invention, these are all referred to as "film") (in the present invention, these are collectively referred to as "laminated aluminum foil"). The method for forming a laminated aluminum foil, which is free from material breakage and wrinkles in the molded product, and which has improved molding limits when molding while controlling the wrinkle holding surface pressure, and a molding machine used for the method. The present invention relates to an aluminum molded product molded by the method.

[0002]

2. Description of the Related Art In the drawing process, the central part of the material is punched, the flange is compressed in the circumferential direction at the corners where breakage is expected, the radial method is pulled, and the part in contact with the shoulder of the die is bent and bent. Receive power such as backlash. At this time, the flange buckles the blank due to the compressive force in the circumferential direction to generate wrinkles, so that an appropriate wrinkle pressing force is applied to the blank holder to suppress wrinkles. This wrinkle holding force has a great influence on the success or failure of processing. The punching force is transferred to the material in the form of tension through the portion that contacts the punch head. Therefore, the success or failure of deep drawing depends on the maximum punching force and the breaking load of the side wall portion (load pulling portion). As the deep-drawing material, the ideal material is preferably one in which the required maximum punching force is smaller than the breaking load of the side wall portion and the extension of the side wall portion is large.

On the other hand, the following means is effective from the drawing surface. (1) Alleviate the localized concentrated load on the fracture risk area. (2) The deformation resistance of the flange portion is reduced. (Shape of tools, improvement of processing conditions, lubrication, etc. are mentioned.) In order to achieve the above-mentioned objects, in the die (punch, die), the shoulder radius of the die, the punch head angular radius, the punch and die Although it is not a simple matter because the gap, punch diameter, etc. each independently or related affect complicatedly, the wrinkle pressing surface pressure is changed during molding, and the flow amount of the molded product in the blank holder (wrinkle pressing) surface, A processing process that controls the drawing conditions such as the amount of overhang can be considered. As specific methods, there are some proposals using a divided blank holder, for example, a method of adjusting the wrinkle holding pressure using a variable bead (JP-A-8-29349).

In addition, in most cases, the wrinkle holding surface pressure of the blank holder is increased in the latter stage of molding to correct the wrinkles once generated (JP-A-63-104729, etc.). Based on the fact that the breakage during draw forming is a mechanism that breaks when the punch load exceeds the withstand load of the side wall of the material in the risk of fracture such as the die shoulder, the punch load is constantly monitored, The punching load is controlled so that the punching load does not exceed the breaking load of the side wall portion.

Therefore, in the constant wrinkle pressing method as shown in FIG. 3, in the molding in which the maximum punch load is reached in the middle of the molding process, the wrinkle pressing force is large in the first half of the molding, small in the middle half of the molding, and needs to be large in the latter half of the molding. There is. Therefore, it is inevitable that the control method becomes complicated. In addition, in the previous example, in order to suppress the thinning of the die shoulder, which is a risk area for fracture, we have proposed a method of reducing the wrinkle holding force in the former period of molding, but depending on the material, the wrinkles that have occurred once are stabilized and corrected. There are problems such as not being able to.

[0006]

DISCLOSURE OF THE INVENTION The present invention uses a reliable and simple apparatus for forming a laminated aluminum foil,
The object of the present invention is to improve the forming limit and to develop a foil forming machine and a pressing method in which wrinkles do not occur in the flange part or the amount of the wrinkles is extremely small.

[0007]

According to the present invention, in the case of an aluminum laminated foil or the like, the higher the adhesion between the aluminum foil as the core material and the resin layer on one side or the front and back sides, the higher the molding limit of the laminated aluminum foil. Focusing on the above, we propose a molding method that constantly increases the vertical surface pressure in the fracture risk area and its vicinity during press molding. That is, [1] In all the steps of press molding of a laminated aluminum foil in which a resin film is laminated on one side or both sides of an aluminum foil, the ratio of the vertical surface pressure of the fracture risk zone to the fracture strength of the laminated aluminum foil is always 0.15. A method for forming a laminated aluminum foil, which comprises performing a press working while maintaining a substantially constant value between 0.50 and 0.50,

[2] In the press molding of a laminate foil in which a resin film is laminated on one side or both sides of an aluminum foil, the punch load is adjusted to 50 to 95% of the breaking load of the laminate foil at the initial stage of the molding, and the surface pressure is reduced. And a method for forming a laminated aluminum foil according to the above [1], in which the wrinkle pressing surface pressure is controlled to a limit surface pressure at which wrinkles are generated in the latter stage of molding.

[3] The method for forming a laminated aluminum foil according to the above [1] or [2], wherein the forming speed of the laminated aluminum foil is 5 to 300 spm (stroke / minute), [4] A method for forming a laminated aluminum foil according to any one of [1] to [3] above, which is a laminated aluminum foil obtained by laminating a resin film on an aluminum foil or an aluminum alloy foil.

[5] In the initial stage of forming, a wrinkle pressing surface pressure is applied so that the punch load is 50 to 95% of the breaking load of the laminated aluminum foil, and thereafter, the wrinkle pressing surface pressure is gradually reduced to make the vertical direction of the breaking risk part. In press working that maintains the ratio of the directional surface pressure / the breaking strength of the laminated aluminum foil at a substantially constant value between 0.15 and 0.50, the timing control of the wrinkle holding surface pressure is controlled by a press cam, limit switch, timer, The method for forming a laminated aluminum foil according to any one of the above [1] to [4] using electrical control of a personal computer or a sequence, [6] Wrinkle holding surface pressure is applied by using air pressure, hydraulic pressure or an elastic body. The method for forming a laminated aluminum foil according to [5] above,

[7] As a molding machine for use in the method for molding a laminated aluminum foil material according to any one of the above [1] to [6], the timing control of the wrinkle pressing surface pressure is performed by a press cam and a limit switch. , A timer, a personal computer or a sequencer electrical control, and a die set part that uses pneumatic pressure, hydraulic pressure or an elastic body to apply pressure to the wrinkle holding surface, forming machine for laminated aluminum foil, [8] Aluminum foil and A laminated aluminum foil made of a resin film is pressed in the entire molding process while maintaining the ratio of the vertical surface pressure of the fracture risk zone / the fracture strength of the laminated aluminum foil to be substantially constant between 0.15 and 0.50. The above problems have been solved by developing a laminated aluminum foil molded product that

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In foil forming of laminated aluminum foil, it is natural that the punch load is formed below the breaking stress of the side wall, but the stress in the forming direction generated on the side wall changes depending on the wrinkle pressing surface pressure. To do. However, in the conventional method, in order to obtain a desired forming height, it is usual to set the highest constant wrinkle pressing surface pressure that is safe and does not exceed the breaking limit in the entire processing process. In the present invention, the range of the punch stroke for reducing the wrinkle holding force varies depending on the shape of the target product in the first stage of molding. For example, since it is different between the cylindrical deep drawing and the rectangular cylindrical drawing, it is impossible to define the absolute value. About 2/3 of the first half of all punch strokes), an excessive wrinkle holding force is applied compared to the conventional method. However, in the present invention, it is necessary to check the breaking load of the side wall portion against the punch load in advance.

Specifically, in the first half of the forming process, the stress in the forming direction of the side wall portion is the breaking limit of the material so that the punching force can surely avoid the breakage of the blank and suppress the generation of wrinkles almost completely. However, by adding a wrinkle holding surface pressure close to it, it is preferably in the range of 50 to 95% of the breaking limit, more preferably 75 to 95%.
The wrinkle pressing surface pressure is applied in the range of%, and the punch force that naturally increases with the progress of the drawing or overhanging process in the latter half of the forming causes the corner R of the punch, the punch shoulder R, or the vicinity of the risk of fracture to occur. A foil forming machine and a method for forming the same while reducing the wrinkle pressing force correspondingly so that the surface pressure in the vertical direction is equal to or less than the breaking limit.

The laminated aluminum foil to which the present invention is applied is a laminated aluminum foil composite material obtained by laminating a resin film on an aluminum foil or an aluminum alloy foil. To do. Suitable for aluminum or aluminum alloy foil is a laminated aluminum foil with polymers such as polyethylene terephthalate and polyamide, low density polyethylene, linear low density polyethylene or polyolefin such as high density polyethylene or polypropylene and other unstretched plastic films. Can be used. As these laminated aluminum foils, those obtained by laminating aluminum foil with a conventional method such as extrusion lamination, sand lamination, or biaxially stretched film by dry lamination can be used.

The vertical surface pressure of the breakable portion is generated by two forces, a wrinkle pressing force and a punch load. In the middle of molding, the punching force increases even if the wrinkle holding force is reduced.
In the present invention, the wrinkle pressing force is correspondingly reduced to form the vertical surface pressure while maintaining a value close to a constant value. The high wrinkle pressing surface pressure applied in the initial stage of molding in the method of the present invention imparts an excessive wrinkle pressing force in the former period of molding as compared with the conventional constant wrinkle pressing surface pressure method, so that the initial stage of wrinkle generation is generated. There is an advantage that swell does not easily occur and the wrinkle height of the molded product can be kept low.

First, the molding limit in the conventional method for comparison will be described. As a typical example, biaxially stretched polyamide (25
When a three-layer aluminum foil composite material of (micron) / aluminum foil (40 micron) / unstretched polypropylene (30 micron) is processed, a molding limit diagram with a constant wrinkle holding pressure by the conventional method is shown in FIG. In this case, the wrinkle region and the fracture region intersect at the position where the molding height is 5.5 mm, and it can be seen that this is the critical height of molding. In addition,
Although this example is a rectangular tube diaphragm, there is no shape restriction in the present invention, and it can be applied to a cylinder or a cross section of a complicated shape without any problem.

FIG. 3 shows typical stroke displacement-punch load at constant wrinkle pressing pressure, which is one of the conventional methods, and wrinkle pressing surface pressure diagram, and stroak displacement-punch load in the variable wrinkle pressing method. The wrinkle pressure line diagram is shown. In the present invention, this is processed while adjusting the ratio of the vertical surface pressure of the fracture risk part / the fracture strength of the laminated aluminum foil so as to maintain a substantially constant value, thereby reliably preventing the fracture of the fracture risk part. At the same time, we succeeded in improving the molding limit and reducing the wrinkle height of the flange.

On the other hand, in the method of the present invention, FIG.
As shown in (1), in the early stage of forming when the punch load is low, the wrinkle pressing force is excessively applied, so that a large vertical surface pressure is applied to the laminated aluminum foil present in the break risk portion near the punch shoulder R. As the punch progresses, the punch load increases, and the vertical surface pressure at the risk of breakage inevitably increases, which reduces the need for wrinkle pressing. To the minimum wrinkle holding force required to prevent). In particular, in drawing forming, most of the forming has a corner R, not to mention the straight portion, so that as the molding progresses, the compressive stress in the circumferential direction of the corner R increases and the inflow resistance of the flange increases.

As a result, the punch load gradually increases. An exception is draw forming, which is based on the assumption that drawing will be omitted.In the initial stage of forming, the punch load increases due to the circumferential compressive stress at the corners of the flange, but in the latter stage of the forming, the punching area is reduced due to pulling in, resulting in punching. The load gradually increases and becomes zero at the same time as passing through the aperture. In this case, the punch load is also small and the wrinkle pressing surface pressure in the latter half of the molding is low,
Although the vertical surface pressure of the fracture risk part is also small, the wrinkle pressing surface pressure is increased in the initial stage of molding, so that local deformation of the fracture risk part is suppressed to some extent in the initial stage, and the molding limit is slightly improved. In FIG. 1, the ratio (H) of the vertical surface pressure of the fracture risk part / the fracture strength of the laminated aluminum foil predicted by the finite element method (numerical analysis) is also shown. In this molding example, the wrinkle holding force was controlled so that the ratio (H) was 0.35 to 0.45 in all steps.

FIG. 4 shows the effect of [ratio of vertical surface pressure / breaking strength of laminated aluminum foil] (H) given to the breaking risk part with respect to the forming height. In the three-layer aluminum foil composite material (breaking strength 89 MPa),
[Ratio of vertical surface pressure / breaking strength of laminated aluminum foil]
When (H) is 0.15 or less, the effect of improving the adhesion strength between the aluminum foil of the laminated aluminum foil and the resin film cannot be obtained, and the molding limit cannot be improved. On the contrary, [ratio of vertical surface pressure / breaking strength of laminated aluminum foil] (H) 0.5
If it is 0 or more, the side wall of the molded body exceeds the breaking stress, and the molding cannot be completed. Therefore, the target [ratio of vertical surface pressure / breaking strength of laminated aluminum foil] (H) is 0.15
0.50, preferably 0.20 to 0.40 is good.

As a result, as shown in FIG. 5, in the processing of the three-layer laminated aluminum foil composite material using this method, the molding limit is 1. The molding limit is controlled by controlling the crease holding force.
Not only 4mm (25%) improvement, but also the height of wrinkle is 5
It can be seen that it has decreased by 0%. In this way, by controlling the wrinkle pressing surface pressure and keeping the ratio (H) of the average vertical surface pressure of the fracture risk area / the breaking strength of the laminated aluminum foil with the progress of processing within a certain constant range, the conventional constant wrinkling can be achieved. It was found that excellent results can be obtained as compared with the processing method performed by the pressing surface pressure.

FIG. 6 shows a schematic view of a foil forming machine for controlling and processing the wrinkle pressing surface pressure of the present invention. The present invention is not limited to this method as long as it is a foil forming machine capable of controlling the wrinkle pressing surface pressure during processing as the processing progresses. This control is
This can be controlled by preparing a molding limit diagram of the material in advance and based on this, adopting a control method in which a solenoid valve for air adjustment is electrically connected to a known press machine cam.

The foil forming machine of FIG. 6 is a conventional foil forming machine such as a die 1, a blank holder (wrinkle retainer) 3, a punch 4, a lower die upper plate 6 and a lower die 8 for controlling the surface pressure of the blank holder 3. Therefore, it is composed of a pin 5, a piston 7 and the like, which are pressure transmitting means such as water pressure, oil pressure or air pressure. In this case, as the pressure control means,
1 shows a pneumatic control device. This device is composed of a solenoid valve 10, an intake valve 11, an air supply port 12, an exhaust valve 13 and the like which are controlled by a device (not shown) that electrically processes signals from a press cam, and controls the pressure of the piston 7. The blank holder 3 is used to control the wrinkle pressing surface pressure, and the material to be molded 2 is processed. The control of the wrinkle pressing surface pressure of the blank holder 3 can be performed by using a personal computer, a sequence limit switch, a timer or the like in addition to the method using the press cam.

[0024]

According to the foil forming method of the present invention, the ratio of the vertical surface pressure / breaking strength of the laminated aluminum foil to the vertical surface pressure of the break risk part of the material and its periphery is always 0.15.
The wrinkle pressing force during molding is controlled so as to be 0.55. Specifically, it is a forming method in which the wrinkle holding force in the first half of the forming is high, and the wrinkle holding surface pressure is controlled so that it falls below the fracture limit of the material as the punch load increases with the progress of forming. A molding machine having a control device suitable for the method. As a result, even if the same material is used, it is possible to reliably prevent breakage of the breakable portion, significantly improve the molding limit, and prevent the occurrence of wrinkles in the flange portion. In particular, when controlling the wrinkle holding surface pressure of the present invention, it becomes possible to reduce the wrinkle height as compared with the conventional method in which the wrinkle holding surface pressure is constant, and it is an off-spec product due to wrinkling of the flange portion. It was possible to reduce significantly, and succeeded in reducing the cost.

[Brief description of drawings]

FIG. 1 is a diagram showing a ratio of stroke displacement-punch load to wrinkle pressing surface pressure, vertical surface pressure / breaking strength of laminated aluminum foil according to the method of the present invention.

FIG. 2 is a molding limit diagram of a conventional laminated foil composite material composed of ON / Al / CPP.

FIG. 3 is a typical stroke displacement-punch load and wrinkle holding surface pressure diagram according to the conventional method.

FIG. 4 is a diagram showing the influence of the ratio of the vertical surface pressure of the fracture risk zone / the fracture strength of the laminated aluminum foil on the forming height according to the method of the present invention.

FIG. 5 is a comparison diagram of the molding height and the wrinkle height in the present invention and the conventional method.

FIG. 6 is a sectional view of an embodiment of a molding machine used for deep drawing of the present invention.

[Explanation of symbols]

1 die 2 Object to be molded 3 Blank holder (wrinkle holder) 4 punch 5 pin 6 Lower mold upper plate 7 pistons 8 Lower mold 9 punch cradle 10 Solenoid valve 11 Air supply valve 12 Air supply port 13 Discharge valve

Claims (8)

[Claims] 1. The ratio of the vertical surface pressure of the fracture risk zone to the fracture strength of the laminated aluminum foil is always 0.15 in all the steps of press forming of the laminated aluminum foil in which a resin film is laminated on one side or both sides of the aluminum foil. ~ 0.50
A method for forming a laminated aluminum foil, which comprises performing press working while maintaining a substantially constant value between the two. 2. In press molding of a laminated aluminum foil in which a resin film is laminated on one side or both sides of an aluminum foil, the punching load is set to 50 to 95% of the breaking load of the laminated aluminum foil in the initial stage of molding in the press molding. The method for forming a laminated aluminum foil according to claim 1, wherein the pressure is controlled so that the wrinkle pressing surface pressure is reduced to a limit surface pressure at which wrinkles are generated in the latter half of the forming. 3. The forming speed of the laminated aluminum foil is 5 to 3
The method for forming a laminated aluminum foil according to claim 1 or 2, which is processed at 00 spm (stroke / minute). 4. The method for forming a laminated aluminum foil according to claim 1, wherein the laminated aluminum foil is a laminated aluminum foil obtained by laminating a resin film on an aluminum foil or an aluminum alloy foil. 5. A vertical direction of a fracture risk part is provided by applying a wrinkle pressing surface pressure at which the punch load is 50 to 95% of the breaking load of the laminated aluminum foil in the initial stage of molding, and gradually decreasing thereafter. In press processing that maintains the surface pressure / laminated aluminum foil rupture strength ratio at a substantially constant value between 0.15 and 0.50, the presser cam, limit switch, timer, and PC are used to control the timing of the crease presser surface pressure. Alternatively, the method for forming a laminated aluminum foil according to any one of claims 1 to 4, wherein electrical control of a sequence is used. 6. The method for forming a laminated aluminum foil according to claim 5, wherein the wrinkle holding surface pressure is applied by using pneumatic pressure, hydraulic pressure or an elastic body. 7. A molding machine for use in the method for molding a laminated aluminum foil according to claim 1, wherein the timing control of wrinkle pressing surface pressure is performed by a press cam,
A laminating aluminum foil molding machine that uses limit switches, timers, electric control of a personal computer or a sequence, and is equipped with a die set part that uses air pressure, hydraulic pressure, or an elastic body to apply pressure to the wrinkle holding surface. 8. A laminated aluminum foil composed of an aluminum foil and a resin film is used in all the steps of molding so that the ratio of the vertical surface pressure at the risk of fracture / the fracture strength of the laminated aluminum foil is 0.15 to 0.50. Laminated aluminum foil molded product that has been pressed while keeping the interval almost constant.