JP6875824B2 - Squeezing blank can - Google Patents

Description

The present invention relates to a squeezed and squeezed blank can. More specifically, the aluminum can is made of aluminum as a main raw material and has an appearance excellent in gloss, and is subjected to post-processing such as neck-in processing. With respect to squeezed and squeezed aluminum blank cans that can be obtained.

Metal cans, especially aluminum cans, which are widely used for beverage cans and the like, are generally manufactured by squeezing and ironing. Examples of the type of squeezing processing include wet molding using a coolant (mixed liquid of water and lubricating oil) and dry molding using an aluminum plate coated with a resin such as polyester resin such as polyethylene terephthalate. (See, for example, Patent Documents 1 and 2).

However, since the outer surface of the resin-coated aluminum can is coated with resin, it is excellent in scratch resistance and corrosion resistance, but its metallic luster is not sufficient.

Further, although the aluminum can obtained by directly drawing and ironing the aluminum plate shows a high metallic luster as compared with the resin-coated can, the metallic luster of the material aluminum is not sufficiently drawn out.
For example, the molding process for manufacturing a metal can is performed by wet molding using a coolant (mixed liquid of water and lubricating oil) or dry molding using no coolant as described above. Even when the aluminum plate is directly squeezed and ironed, the metallic luster is not sufficient. In wet molding, the molding process is performed in the mixed lubrication region where coolant is interposed on the surface of the molding process, so it is not possible to sufficiently bring out the metallic luster. In dry molding, the surface of the molding process and the molding jig (for ironing) Not only does it have low slipperiness with the die) and the surface becomes rough, but in many cases, the can is broken and cannot be molded in the first place.

Patent No. 3440688 Patent No. 5609036

An object of the present invention is to provide a squeezed and squeezed blank can which is not resin-coated and has an appearance excellent in metallic luster.

As a result of examining the metallic luster of aluminum cans, the present inventors have examined the metallic luster of aluminum cans. It has been found that the surface roughness of the above-mentioned material is effectively suppressed and an appearance having an excellent metallic luster is exhibited, and the present invention has been completed.

According to the present invention, in a squeezed and ironed blank can
The maximum height roughness Rz1 in the circumferential direction on the outer surface of the thinnest part of the body is 0.5 μm or less, and
Seen from the side, the ratio Ra1 / Ra2 of the circumferential average surface roughness Ra1 on the outer surface of the thinnest part of the body and the circumferential average surface roughness Ra2 on the outer surface of the lower end of the body is 0.8 to 1. A squeezed and squeezed blank can characterized by being .2 is provided.
In the present invention, the squeezed and squeezed blank can means a molded product obtained by squeezing and squeezing before being subjected to neck-in processing or the like.

In the squeezed and ironed blank can of the present invention,
(1) The main raw material of the squeezed and ironed blank can is aluminum.
Is preferable.

In the squeezed iron blank can of the present invention, the maximum height in the circumferential direction and the surface roughness Rz1 on the outer surface of the thinnest part of the body show an extremely small value of 0.5 μm or less. It also shows that the surface roughness generated during processing is effectively suppressed.
That is, the squeezed iron blank can of the present invention exhibits excellent metallic luster because surface roughness is effectively suppressed. Therefore, an aluminum can obtained by performing post-processing such as neck-in processing on such a blank can has a high metallic luster exhibited by the blank can as it is in its body, and has an extremely high commercial value. It becomes.
Further, in the squeezed ironing blank can (blank can) of the present invention, the maximum height surface roughness Rz1 is 0.5 μm or less, which is excellent in metallic luster, and at the same time, the average surface roughness is as described above. The ratio (Ra1 / Ra2) is 0.8 to 1.2, which is close to 1. That is, both the thinnest portion and the lower end portion of the body portion have smooth surfaces, and excellent metallic luster is exhibited on the entire outer surface thereof.

Schematic side sectional view of the blank can of the present invention. The figure which shows the outline of the punching and drawing process for manufacturing the blank can of this invention. The figure which shows the outline of the ironing process performed after the drawing process of FIG. The figure which shows the micrograph (700 times) which shows the outer surface of the blank can of this invention obtained by ironing under the dry condition using the ironing die provided with the smoothed diamond film on the processed surface. Yes, (a) is the outer surface of a blank can obtained by molding under wet conditions using a cemented carbide ironing die, and (b) is the processed surface of a smoothed diamond film. The outer surface of a blank can obtained under dry conditions (low lubrication method) using the ironing die formed in (c) is ironed with a smoothed diamond film formed on the processed surface. The outer surface of a blank can obtained under dry conditions (non-smoothing method) using a die is shown.

<Form of squeezed blank can>
The squeezed ironing blank can (hereinafter, simply referred to as a blank can) of the present invention is a molded product obtained by ironing processing described later and before post-processing such as neck-in processing, and therefore, as shown in FIG. In addition, it has an extremely simple form.

That is, with reference to FIG. 1, the blank can shown by 10 as a whole has a bottomed tubular shape as a whole, and has a straight body 1 extending downward from the upper end and a lower end of the body 1. It consists of a bottom 3 connected to the bottom 3.

The blank can 10 of the present invention having the above-described form has an excellent metallic luster on its outer surface, and is manufactured as follows.
<Manufacturing of blank cans>
The blank can of the present invention having the above-described form is mainly produced by molding using a metal plate known per se.
The metal plate provided by the molding process, for example, an aluminum plate, may be pure aluminum, or may be an alloy of aluminum and another metal, for example, an aluminum alloy containing magnesium, manganese, or the like. Further, the plate material may be another metal such as iron, titanium or magnesium, or an alloy containing another metal as a main raw material, or a plated plate such as tinplate.

Further, in the present invention, in order to impart excellent metallic luster to the outer surface of the blank can, it is preferable that at least the surface of the metal plate located on the outer surface side of the can is not coated with 100 nm or more. This is because if a material having a coating having a certain thickness or more on the outer surface is subjected to a molding process, the metallic luster of the metal material is impaired.
Therefore, as long as the surface located on the outer surface side of the can is not covered, the above metal plate may be coated on the surface located on the inner surface side of the can, for example, a polyester resin typified by polyethylene terephthalate. A thermoplastic resin film may be laminated, whereby the corrosion resistance on the inner surface side of the can may be enhanced.

Further, the above-mentioned metal plate exhibits metallic luster even if the surface is coated with an ultra-thin film of several tens of nm or less by an oxide film, resin or the like by anodizing, chemical conversion treatment, etc., but exhibits higher metallic luster. In some cases, it is desirable that the metal material is exposed on the surface without an ultra-thin coating.

The molding process using the metal plate as described above is performed by punching process, drawing process, and ironing process. FIG. 2 shows an outline of a punching process and a drawing process, and FIG. 3 shows an outline of a re-drawing-squeezing process.

With reference to FIG. 2, the above-mentioned base plate 11 made of a metal material (the side corresponding to the inner surface of the can may be coated) is first subjected to a punching process, whereby a disk for a can is formed. 13 is obtained (see FIG. 2 (a)).
In such punching, a punching punch 15 having an outer diameter corresponding to the diameter of the disk 13 and a die 17 holding the base plate 11 and having an opening corresponding to the diameter of the disk 13 are used. That is, a disk 13 having a predetermined size can be obtained by punching the base plate 11 held on the die 13 by the punch 15.

The disk 13 obtained as described above is subjected to drawing processing, whereby a drawing can (bottomed tubular body) 19 having a low height can be obtained (see FIG. 2B).
In such drawing processing, the punched disk 13 is held on the die 21, and the periphery of the disk 13 is held by the wrinkle pressing jig 23. An opening is formed in the die 21, and the drawing can 19 can be obtained by pushing the disk 13 into the opening of the die 21 using the drawing punch 25.

A radius (curvature portion) is formed at the upper end corner portion (the side holding the disk 13) of the opening of the die 21 so that the disk 13 does not break quickly and inside the opening of the die 21. The outer diameter of the punch 25 is set to be smaller than the diameter of the opening of the die 21 by a portion corresponding to approximately the thickness of the disk 13. That is, in this drawing process, thinning is hardly performed. The drawing process may be performed a plurality of times depending on the shape of the molded product.

Next, the squeezed can 19 obtained above is subjected to the re-squeezing-squeezing process shown in FIG. 3, whereby a blank can 10 having a high height and a small diameter and a thin wall can be obtained.

In this redrawing-ironing process, a ring-shaped redraw die 31 and a plurality of ironing dies 33a to 33c are arranged in this order, respectively, and are located on the most downstream side in the processing direction for ironing. A guide ring 35 is arranged on the downstream side of the die 33c, and a holding ring 37 and a holding rod 37a for forming the bottom are provided on the downstream side in this order.
The ironing dies 33a to 33c have a smaller diameter as they go toward the dies 33a to 33c (as they go downstream in the machining direction), and the wall thickness is reduced.

During re-squeezing-squeezing, the above-mentioned drawing can 19 is held on the redraw die 31 by a holder 41, and in this state, a punch 43 for ironing is inserted inside the drawing can 19, and the dies 31, 33a to By moving the punch 43 in the processing direction while pressing the outer surface of the drawing can 19 against the inner surface (processed surface) of 33c, re-squeezing and ironing are performed, and the side wall of the drawing can 19 is thinned. It becomes. As a result, the blank can 10 having the form shown in FIG. 1, that is, the blank can 10 which is thinned and whose height is increased according to the degree of thinning can be obtained.

In the present invention, the ironing process is performed under dry conditions and without lubrication without using a coolant.

Further, the tip portion of the punch 43 for ironing processing has a tapered shape corresponding to the bottom portion 3 of the blank can 10 described above. Further, the holding ring 37 is provided so as to be slidable along the machining direction, and the holding rod 37a is inserted into the central portion of the ring, and the inner peripheral surface of the holding ring 37 and the upper end of the holding rod 37a are , Has a shape corresponding to the bottom 3 of the blank can 10 of FIG.
That is, the squeezing can 19 is extruded through the dies 31, 33a to 33c described above by the squeezing punch 43, and the bottom of the processed product of the squeezed can 19 is further attached to the holding ring 37 and the holding rod 37a. It is pressed and thereby shaped into the form of the bottom 3 described above, resulting in a blank can 10. When the blank can 10 is formed in this way, the ironing punch 43 moves upstream in the processing direction, and the obtained blank can 10 is held by the guide ring 35 and pulled out from the ironing punch 43. , The blank can 10 is taken out.
The blank can 10 thus obtained is subjected to a post-process such as neck-in processing and further winding and tightening in the next post-process, and is used as a metal can.

In the ironing process as described above, in FIG. 3, three ironing dies are arranged and ironing is performed in three stages, but the number of the ironing dies is three. The number is not limited to the above, and can be adjusted to an appropriate number according to the desired thinning and the height of the can, and can be squeezed in one stage with one die, or 2 or. More dies can be arranged for ironing in multiple stages. Of course, when a plurality of ironing dies are arranged along the processing direction and the ironing is performed in multiple stages, as described above, the inner diameter (machining diameter) thereof is increased as it goes downstream in the machining direction. Is getting smaller.
For example, the above-mentioned ironing process is usually performed using an ironing die having an appropriate diameter and number so that the ironing rate defined by the following formula is 50% or less.
Ironing rate (%) = (ironing amount / thickness before ironing) x 100

Further, in the above-mentioned ironing process, in order to obtain the blank can 10 of the present invention, diamond is used as the ironing dies 33a to 33c on the processed surface (the surface in contact with the outer surface of the squeezed can 19 to be ironed). It is necessary to use a diamond film provided with a film and to have a surface with high smoothness by surface polishing. Of course, even when ironing is performed by arranging a number of dies other than three, it is necessary that all the ironing dies used are provided with a diamond film on the processed surface.
By using a squeezing die provided with such a diamond film, an excellent metallic luster can be exhibited on the outer surface of the obtained blank can.

In the present invention, the above-mentioned diamond film is provided on at least the processed surface (the surface in contact with the outer surface of the drawing can 19 which is the material to be processed) of the ironing die made of a rigid base material which is usually used. As the base material, a material having rigidity that can withstand harsh ironing with high surface pressure and heat resistance that can withstand high-temperature heating during film formation of a diamond film is used.
Examples of such a material include a so-called superhard alloy obtained by sintering a mixture of tungsten carbide (WC) and a metal binder such as cobalt, a metal carbide such as titanium carbide (TiC), and titanium carbonitride (Titanium carbonitride). Cermet obtained by sintering a mixture of a titanium compound such as TiCN) and a metal binder such as nickel or cobalt, or silicon carbide (SiC), silicon nitride (Si ₃ N ₄ ), alumina (Al ₂ O ₃ ), Hard ceramics such as zirconia (ZrO ₂ ) can be mentioned.

The diamond film as described above is produced by forming a film on the surface of the rigid base material 31 by a known method such as a CVD method, for example, a thermal filament CVD method, a microwave plasma CVD, or a high frequency plasma CVD.

When forming a film, a gas obtained by diluting a hydrocarbon gas such as methane, ethane, propane, or acetylene with hydrogen gas to about 1% is generally used as the raw material gas, and the raw material gas has a film quality and a film forming rate. For preparation, a small amount of gas such as oxygen, carbon monoxide, and carbon dioxide may be mixed as appropriate.
Using the above raw material gas, the rigid base material is heated to a high temperature of 700 to 1000 ° C., the raw material gas is decomposed to generate active species, and diamond crystals are grown on the rigid base material to form a film. Will be done. In such a film formation, the dissociated hydrogen atoms selectively etch graphite or amorphous carbon generated on the rigid substrate, whereby a large amount of diamond component can be formed.

In the present invention, the surface of the diamond film formed as described above is polished.
Since the diamond film formed by means such as CVD has a polycrystalline structure, the surface is rough. Therefore, it is necessary to make the surface of the diamond film a smooth surface by surface polishing.
For example, in order to obtain the above-mentioned aluminum can having an outer surface having excellent brilliance, the surface roughness Ra (JIS B-0601-1994) is polished to 0.1 μm or less, particularly 0.05 μm or less. Is done.

The surface polishing of the diamond film can be performed by a method known per se.
For example, it may be a mechanical polishing method in which a diamond film is co-polished using diamond abrasive grains (grinding stones), or a polishing method using a chemical action. A polishing method that combines these mechanical and chemical methods may be used.

Excellent metallic luster by performing ironing using a ironing die provided with a diamond film having a smooth surface as described above under dry conditions without using coolant. A blank can of the present invention having an outer surface can be obtained.

<Metallic luster of blank cans>
Returning to FIG. 1 again, the blank can 10 of the present invention obtained by the above-mentioned ironing process has at least an outer surface not coated with resin, and has a maximum circumferential direction of the outer surface at the thinnest portion X of the body portion 1. Height Surface roughness Rz1 (JIS-B-0601-2001) is 0.5 μm or less, which means that surface roughness during ironing is suppressed, the outer surface is smoothed, and high metallic luster is exhibited. Show that you are doing.
As shown in FIG. 1, the thinnest portion X of the body portion is a region having a thickness of ± 5 um, which is the thinnest portion of the body portion 1.

That is, in squeezing and ironing under wet conditions using a base plate not coated with resin, an oil film enters the interface between the ironing die and the metal surface, so that the transfer rate of the die surface to the blank can decreases. The surface is roughened, resulting in impaired metallic luster.
However, when ironing is performed using the ironing die having the smoothed diamond film on the processed surface, the coefficient of friction between the smoothed diamond film and the metal surface is extremely small, and the die Since the slipperiness between the machined surface and the metal surface is remarkably improved, it is possible to mold under dry conditions where the amount of lubricant used is extremely small or not used at all, and as a result, the above-mentioned surface roughness becomes effective. The surface roughness Rz1 which is suppressed and the maximum height in the circumferential direction at the thinnest portion X of the body portion shows a low value as described above, and a high metallic luster is exhibited on the outer surface thereof.
For example, in the ironing process under wet conditions using a normal superalloy ironing die in which a diamond film is not formed on the processed surface, the above-mentioned peripheral maximum height surface roughness Rz1 is surface roughness. The higher the value, the lower the metallic luster.

Further, when the above-mentioned ironing process is performed under wet conditions using a coolant (a mixture of a lubricant such as wax and water), the maximum height in the circumferential direction at the thinnest portion X of the body X and the surface roughness Rz1 Is larger and is not much different from ironing under wet conditions using a normal superalloy ironing die.
That is, in the ironing process in the wet process, the ironing process is performed with the lubricating film (coolant) interposed between the processed surface of the ironing die and the metal surface, so that the metallic luster of the material is sufficiently brought out. It can not be said. However, in the ironing process using the die in which the smoothed diamond film is formed on the processed surface as described above, the surface pressure of the hard diamond film is directly high on the metal surface while showing high slipperiness to the metal surface. The metal surface is smoothed more effectively as compared with the case where the lubricating film is interposed, the above-mentioned maximum height in the circumferential direction surface roughness Rz1 becomes a lower value, and a higher metallic luster is exhibited. Will be done.

As described above, the outer surface of the blank can 10 of the present invention exhibits an excellent metallic luster.
For example, FIG. 4 shows a photomicrograph (700) of the outer surface of the blank can of the present invention obtained by ironing under dry conditions using an ironing die having a smoothed diamond film on the processed surface. Double) is shown. FIG. 4A shows the outer surface of a blank can obtained by molding under wet conditions using a cemented carbide ironing die, and FIG. 4B shows the processed surface of a smoothed diamond film. The outer surface of the blank can obtained under dry conditions (low lubrication method) using the die formed in (c) is dried using a die having a smoothed diamond film formed on the processed surface. This is the outer surface of a blank can obtained under conditions (non-lubricated method).
As shown in this figure, it can be seen that the surface roughness of the outer surface of the blank can of the present invention is effectively suppressed.

Further, since the blank can of the present invention is obtained by ironing under dry conditions and in a non-lubricating method, the average surface roughness Ra1 in the circumferential direction at the thinnest portion X of the body portion and the circumference at the lower end portion Y of the body portion Y. The ratio (Ra1 / Ra2) to the direction average surface roughness Ra2 is in the range of 0.8 to 1.2 and shows a value close to 1.
As shown in FIG. 1, the lower end portion Y of the body portion is a region between the lower end portion 1a of the body portion and the lower end portion 1a of the body portion, which is 3 mm higher.

That is, according to the research by the present inventors, in the ironing process using a low lubrication method using a solid lubricant even under wet conditions using a coolant or dry conditions, the smoothed diamond film described above is processed on the processed surface. Even by the ironing process using the ironing die provided in the above, the lower portion of the obtained Al blank can, particularly the lower end portion Y to the bottom portion 3 of the body portion 1 is not sufficiently smoothed, for example, the thinnest portion of the body portion. It has been confirmed that the circumferential average surface roughness Ra2 at the lower end portion Y is considerably larger than the circumferential average surface roughness Ra1 at X. This is because in ironing, the lubrication required for processing is achieved by bringing a lubricant to the interface between the ironing die and the material due to the pressure change due to the processing, but due to the contact between the die and the material at the initial stage of ironing. A sudden pressure change occurs with the impact load, and more lubricant is brought in, which reduces the transfer rate of the mold surface to the blank can and impairs smoothing near the lower end 1a of the body 1. Because it is. Therefore, by using the above-mentioned ironing die having a diamond film on the processed surface and at the same time performing ironing by a non-lubricating method under dry conditions, smoothing is hindered at the bottom and the lower end Y of the body by the lubricant. Is effectively prevented, and the average surface roughness Ra2 of the lower end portion Y of the body portion is also low as in the case of the thinnest portion X of the body portion, and the surface roughness ratio (Ra1 / Ra2) is close to 1. I think it shows.
As described above, the fact that the surface roughness ratio (Ra1 / Ra2) shows a value close to 1 means that both the thinnest portion X of the body portion and the lower end portion Y of the body portion have high metallic luster, and as a result, the entire body portion 1 is exhibited. It shows that excellent metallic luster is uniformly exhibited over the entire period.

As described above, the blank can of the present invention has an excellent metallic luster, and has an extremely high commercial value as a metal can in which the metallic luster is maximized by subjecting it to post-processing such as neck-in processing. ..
Moreover, it can be manufactured by ironing under dry conditions, does not require cleaning equipment or chemicals for removing coolant, and is extremely advantageous in terms of manufacturing cost.

The present invention will be described with reference to the following experimental examples.
In the following experimental example, the surface roughness was measured by the following method.
Surface roughness:
Using a surface roughness meter manufactured by Tokyo Seimitsu Co., Ltd. (Surfcom 2000SD3), the arithmetic mean roughness Ra and the maximum height surface roughness Rz were measured in accordance with JIS-B-0601.

<Experimental example 1>
Cemented carbide die for ironing + coolant lubrication (wet condition), diamond coat die + solid lubricant (dry condition low lubrication method), diamond coat die + no lubricant (dry condition non-lubrication method) The aluminum plate was squeezed. The aluminum plate was made by rolling A3104 material to a plate thickness of 0.27 mm, punching it, and drawing it to form a bottomed tubular body of Φ95 mm, which was used in the molding test. In the molding test, a punch with an outer diameter of Φ66 mm was moved at a speed of 1 m / s using a hydraulic press, and first drawing was performed to form a tubular body with a diameter of Φ66 mm, which was then subjected to three ironing processes as it was. .. Table 1 shows the maximum height surface roughness Rz1 of the outer circumference of the can of the thinnest part X of the body at that time.

According to Table 1, the surface roughness under dry conditions is smaller than that under wet conditions. Further, in the processing under dry conditions using a cemented carbide ironing die, the aluminum is broken and cannot be formed. These are in agreement with the enlarged photographs and visual results of the outer surface of the blank can shown in FIG. 4, and the less lubricant used for molding, the higher the transfer rate of the die surface to the blank can, and it is possible to bring out the metallic luster. Is.

<Experimental example 2>
Next, Table 2 shows a comparison of the surface roughness between the thinnest part of the body and the lower end of the body.

According to Table 2, the low-lubrication method using solid lubricant and the non-lubrication method without lubricant are in the middle of processing, and the surface roughness Ra1 of the thinnest part of the body, which is difficult to process, is almost the same, but ironing. The surface roughness Ra2 of the lower end of the body portion at the initial stage of processing is remarkably different, and the ratio Ra2 / Ra1 is around 1.0 in the non-lubricated method, whereas the value is large in the low lubricated method. That is, even if the total amount of the lubricant is small, a large amount of oil is brought in at the start of processing, so that the surface roughness increases and the metallic luster becomes uneven. On the other hand, it is possible to achieve a uniform metallic luster from the start of processing to the end of processing by performing processing by a non-lubricating method in which oil cannot be brought in.

From the above experimental example, in order to obtain a blank can that shows high metallic luster in the thinnest part of the blank can body that occupies most of the product and has high commercial value, it is necessary to iron it under dry conditions. It is necessary to have a smooth diamond film on at least the surface of the ironing die that comes into contact with the material. In addition, in order to obtain a uniform metallic luster from the lower end to the upper end of the blank can, it is necessary to perform a non-lubricating ironing process that does not use any lubricant even under dry conditions.

The technical scope of the present invention is not limited to the above embodiments and examples, and various modifications can be made without departing from the spirit of the present invention.

1: Body 3: Bottom 10: Squeezed and squeezed blank can (blank can)

Claims (2)

In a squeezed iron blank can whose outer surface is not coated with resin
The maximum height roughness Rz1 in the circumferential direction on the outer surface of the thinnest part of the body, which is the region of the thickness of ± 5 um, which is the thinnest part of the body, is 0.5 μm or less.
When viewed from the side, the circumferential average surface roughness Ra1 on the outer surface of the thinnest part of the body and the circumferential average on the outer surface of the lower end of the body, which is the area between the lower end of the body and 3 mm higher than the lower end of the body. A squeezed and squeezed blank can characterized in that the ratio Ra1 / Ra2 to the surface roughness Ra2 is 0.8 to 1.2. The squeezed iron blank can according to claim 1, wherein the main raw material of the squeezed iron blank can is aluminum.

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