JP2018145466A - Manufacturing method of aluminum alloy sheet for beverage can excellent in bottom moldability and bottom part strength - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an aluminum alloy sheet for beverage can excellent in bottom moldability and bottom part strength.SOLUTION: An aluminum alloy sheet having sheet thickness of 0.210 to 0.470 mm and bearing force after coating galling of 230 to 320 N/mmis provided by conducting CAL annealing with holding temperature of 300 to 540°C for 5 to 60 sec. once or two times by using a continuous annealing device in a process of cold rolling, and a final stabilization annealing under a condition of temperature increase rate of 3°C/min. or more, holding temperature of 120 to 140°C, holding time of 1 to 2 hr. and cooling rate of 10°C/min. or more after final cold rolling when an aluminum alloy sheet is manufactured through a homogenization process, a soaking treatment on an ingot obtained by smelting an aluminum alloy containing, by mass%, Si:0.35% or less, Fe:0.35 to 0.55%, Cu:0.15 to 0.48%, Mn:0.8 to 1.15%, Mg:0.60 to 1.60%, and semi-continuously casting the same; hot rough rolling; hot finish rolling and cold rolling.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for producing an aluminum alloy plate for beverage cans having excellent bottom formability and bottom portion strength.

Al-Mn-Mg based alloy hard plates such as JIS3004 (AA3004) or JIS3104 alloy are used for the can body of aluminum beverage cans. The alloy hard plate is required to have strength and corrosion resistance necessary for use as a container, a beautiful appearance, and excellent formability.
The hard plate of the aluminum alloy is manufactured through processes such as melting, casting, homogenization, hot rolling, cold rolling and the like in the same manner as a general aluminum alloy plate.

  However, if the mechanical properties of the aluminum alloy rolled plate are anisotropic, the formability when forming the can body is hindered, the symmetry of the can body after forming is reduced, and the material usage yield is reduced. There are problems such as lowering. The anisotropy of the rolled sheet depends on the crystal grain orientation distribution (texture). Therefore, it is considered that the anisotropy of the rolled aluminum alloy sheet can be reduced by taking into account the change in texture due to cold rolling and controlling the texture that occurs during recrystallization before cold rolling.

From the above viewpoint, in order to control the anisotropy of the aluminum alloy rolled sheet, it is important how to control the recrystallization before cold rolling. From this viewpoint, the production of the aluminum alloy sheet for beverage cans Methods can be classified into the following three types.
(1) Hot rolling → Recrystallization → Final cold rolling In the first method, hot rolling is performed to a relatively thin aluminum alloy sheet of, for example, 3 mm or less, and after hot rolling, it is wound on a coil. This is a method in which recrystallization is performed as it is, or after artificial annealing and recrystallization, and then cold rolling.
(2) Hot rolling → low-pressure cold rolling → recrystallization → final cold rolling The second method is hot rolling to a relatively thin-walled aluminum alloy sheet of, for example, 3 mm or less, and then under a relatively low pressure. For example, as described in the following Patent Document 1, after performing cold rolling of 6 to 15% on an aluminum alloy sheet, annealing is performed, and finally the final cold rolling with a reduction rate of about 90% is performed. is there.
(3) Hot rolling → cold rolling → recrystallization using a continuous annealing furnace → final cold rolling at a relatively low pressure The third method is to perform first cold rolling after hot rolling of an aluminum alloy sheet. Thereafter, using a continuous annealing furnace, annealing is performed by rapid heating to a relatively high temperature, followed by rapid cooling, and finally cold rolling at a relatively low pressure reduction rate of, for example, about 60%.

  In addition, a technique for performing cold rolling after hot rolling and performing recrystallization annealing and then performing cold rolling again is described in Patent Document 2 below, and a technique for performing finish annealing after cold rolling is described in the following patent. It is described in Document 3.

Japanese Patent No. 3644819 Japanese Patent Laid-Open No. 4-13852 Japanese Patent Laid-Open No. 4-56743

By the way, there is a strict demand for lower prices for aluminum cans. For this reason, the cans are being made thinner and lighter, but with the thinner and lighter weights, the bottom formability and bottom strength of the can (particularly against stress in the axial direction of the can). Ensuring buckling strength is required.
As a means of ensuring the bottom formability and the bottom part strength, it is possible to consider a method of performing annealing after the final cold rolling, improving the deep drawing formability, and improving the stretch formability. If annealing is performed later, the mechanical properties of the material itself change and the microstructure also changes.

  The present invention has been made to solve the above-described problems, and is an aluminum alloy plate for beverage cans that has excellent bottom formability and bottom portion strength without causing changes in the mechanical strength and microstructure of the material itself. It aims at providing the method of manufacturing.

The manufacturing method of the aluminum alloy plate for can bodies of this invention is mass%, Si: 0.35% or less, Fe: 0.35-0.55%, Cu: 0.15-0.48%, Mn: An ingot obtained by melting an aluminum alloy having a composition containing 0.8 to 1.15%, Mg: 0.60 to 1.60%, the balance being Al and inevitable impurities, and semi-continuously casting After homogenization treatment, soaking treatment, hot rough rolling, hot finish rolling, and cold rolling to produce an aluminum alloy sheet for beverage cans, once using a continuous annealing device during the cold rolling. Or twice, continuous annealing is performed at a temperature of 300 to 540 ° C. for 5 to 60 seconds, and after the final cold rolling, a heating rate of 3 ° C./min or more, a holding temperature of 120 to 140 ° C., a holding time of 1 to 2 hours, Final stabilization annealing is performed at a cooling rate of 10 ° C./min or more, and the sheet thickness is 0 210～0.470Mm, characterized in that to obtain an aluminum alloy plate strength 230~320N / mm ² after baking.

In the present invention, the homogenization treatment performed on the ingot is performed under the condition of heating at 555 to 605 ° C. for 4 to 10 hours, and the soaking is performed at the temperature of heating at 500 to 555 ° C. for 1 hour or more. Is set to 400 to 460 ° C., hot rough rolling is performed, the finishing plate thickness is set to 2.0 to 3.6 mm, the finishing temperature is set to 240 to 360 ° C., and hot finishing rolling is performed. It is preferable to perform cold rolling with the cold rolling rate set to 76 to 95%.
In the present invention, aluminum containing at least one or more of Cr: 0.05% or less, Zn: 0.25% or less, Ti: 0.10% or less with respect to the composition. It is preferable to use an alloy.

The method for producing an aluminum alloy plate for a can body according to the present invention includes melting an aluminum alloy having a specific range of Si, Fe, Cu, Mn, and Mg, hot rough rolling, hot finish rolling, and cold rolling. During the cold rolling, continuous annealing is performed at a temperature of 300 to 540 ° C. for 5 to 60 seconds, and after the final cold rolling, the heating rate is 3 ° C./min or more, the holding temperature is 120 to 140 ° C. Since final stabilization annealing is performed for 1 to 2 hours at a cooling rate of 10 ° C./min or more, an aluminum alloy plate for beverage cans having excellent bottom formability and excellent bottom portion strength can be produced.
By performing final stabilization annealing on the above-mentioned conditions, the bottom buckling tolerance after can formation improves.

Explanatory drawing which shows the apparatus and process which are used in a hot rolling process, when implementing the manufacturing method which concerns on this invention. The schematic block diagram which shows an example of the continuous annealing apparatus used for implementation of the manufacturing method which concerns on this invention. Process drawing which shows an example of the manufacturing method of DI can. The fragmentary sectional view which shows an example of DI can.

Hereinafter, although each embodiment of the manufacturing method of the aluminum alloy plate for beverage cans which is excellent in bottom moldability and excellent in the bottom part strength according to the present invention will be described, the present invention is not limited to the embodiment described below. Absent.
First, the composition of the aluminum alloy plate for can bodies used in the present embodiment will be described.
The aluminum alloy plate for a can body according to the present embodiment is, by mass, Si: 0.35% or less (excluding 0%), Fe: 0.35 to 0.55%, Cu: 0.15 to 0.48. %, Mn: 0.80 to 1.15%, Mg: 0.60 to 1.60% or less, and the balance is made of an aluminum alloy having a composition of inevitable impurities and Al. Further, an aluminum alloy containing one or more of Cr: 0.05% or less, Zn: 0.25%, Ti: 0.10% or less in the aluminum alloy having the above composition ratio. It may be used.
Hereinafter, the reasons for limiting the composition of the aluminum alloy used in this embodiment will be described.
In addition, content of each element described in this specification is mass% unless otherwise specified, and includes an upper limit and a lower limit unless otherwise specified. For example, the notation of 0.35 to 0.55% means 0.35% or more and 0.55% or less. Moreover, when noting ranges, such as temperature and time, an upper limit and a lower limit are included unless otherwise specified. For example, 300 to 540 ° C. means 300 ° C. or more and 540 ° C. or less, and 1 to 2 hours means 1 hour or more and 2 hours or less.

"Si: 0.35% or less"
Si easily forms a compound with Mg contained at the same time, has a solid solution hardening action, a dispersion hardening action and a precipitation hardening action, and forms a compound with Al, Mn, Fe, etc., and seizes the die during molding. There is an effect to prevent. If the Si content exceeds 0.35% by mass, workability deteriorates, which is inconvenient.
"Fe: 0.35-0.55%"
Fe has the effect of preventing crystal fineness and seizure to a die during molding. If the Fe content is less than 0.35% by mass, the desired effect cannot be obtained, and if it exceeds 0.55% by mass, the workability deteriorates.

"Cu: 0.15-0.48%"
Cu easily forms a compound with Mg, and contributes to solid solution hardening, dispersion hardening, and precipitation hardening.
If the Cu content is less than 0.15% by mass, the desired effect cannot be obtained, and if it exceeds 0.48% by mass, the workability deteriorates.
“Mn: 0.8 to 1.15%”
Mn is easy to form a compound with Fe, Si, Al, etc., becomes a crystallization phase and a dispersed phase, exhibits a dispersion hardening action, and has an effect of preventing seizure to a die during molding. If the Mn content is less than 0.8% by mass, the desired effect cannot be obtained, and if it exceeds 1.15% by mass, the workability deteriorates.
“Mg: 0.60 to 1.60%”
Mg has a solid solution strengthening action, enhances work hardening by rolling, and exhibits dispersion hardening and precipitation hardening action by coexisting with Si and Cu. If the Mg content is less than 0.60% by mass, the desired effect cannot be obtained, and if it exceeds 1.60% by mass, the workability deteriorates.

In the aluminum alloy used in the present embodiment, in addition to the main components of Si, Fe, Cu, Mn, and Mg, one or more of the following Cr, Zn, and Ti may be contained.
"Cr: 0.05% or less"
Cr exhibits the effect of preventing seizure on the die during crystal refinement and molding. If the Cr content exceeds 0.05% by mass, it becomes brittle and the workability deteriorates, so 0.05% by mass or less is desirable.

“Zn: 0.25% or less”
Zn has the effect of refining Mg, Si and Cu precipitates. If the Zn content exceeds 0.25% by mass, the workability and corrosion resistance deteriorate, so when Zn is added, the content is preferably 0.25% by mass or less.
“Ti: 0.10% or less”
Ti has the effect of improving the workability by refining crystal grains. However, if the Ti content exceeds 0.10% by mass, a coarse compound is formed, and conversely, the workability is deteriorated. Therefore, the content is preferably 0.10% by mass or less.

<Method for producing aluminum alloy plate for beverage can excellent in bottom moldability and bottom portion strength>
Next, an embodiment of a method for producing an aluminum alloy plate for beverage cans excellent in bottom formability and bottom portion strength according to this embodiment will be described.
In the method for producing an aluminum alloy plate for beverage cans according to this embodiment, the aluminum alloy having the above composition is melted and subjected to homogenization treatment and soaking treatment on the ingot obtained by casting, followed by hot roughening. Hot rolling is performed by rolling and subsequent hot finish rolling, and cold rolling is performed to obtain an aluminum alloy plate for a beverage can having a desired plate thickness.
Furthermore, in the above-mentioned process, continuous annealing (CAL annealing) is performed at a temperature of 300 to 540 ° C. for 5 to 60 seconds once or twice using a continuous annealing apparatus during the cold rolling, and the final cold After rolling, it is important to perform final stabilization annealing under conditions of a heating rate of 3 ° C./min or more, a holding temperature of 120 to 140 ° C., a holding time of 1 to 2 hours, and a cooling rate of 10 ° C./min or more.
Hereafter, the manufacturing method of the aluminum alloy plate for drink cans which is excellent in the bottom moldability and bottom part intensity | strength of this embodiment is demonstrated in order of a process.

"casting"
After the aluminum alloy having the above composition is melted, an ingot is cast from the molten aluminum alloy according to a conventional method. When the aluminum alloy is melted prior to casting, inclusions such as hydrogen gas and oxide are removed, An ingot is obtained by a continuous casting method.
The solidification rate in this semi-continuous casting is usually 5 to 20 ° C./second. The thickness of the cast ingot can be about 500 to 600 mm, for example.
Next, chamfering of the ingot is performed, and the surface of the ingot is cut by about 1 to 25 mm to produce a face cut body. The chamfering may be performed after a homogenization process described later.

"Homogenization treatment"
Next, a homogenization process is performed on the manufactured face cut body. The homogenization treatment is generally performed for homogenization of microsegregation generated by solidification of the molten metal, precipitation of supersaturated solid solution elements, transition of a metastable phase formed by solidification to an equilibrium phase, and the like.
In the homogenization treatment, it is important that the homogenization temperature is in the range of 555 to 605 ° C. When the homogenization temperature is less than 555 ° C., the effect of continuous annealing described later cannot be obtained, cracks are easily generated in the hot rolling process and the cold rolling process described later, and the ear rate of the final plate material is increased. Further, if the homogenization temperature exceeds 605 ° C, the ingot may be melted.

In the homogenization treatment, it is preferable to heat the face milling body to a homogenization temperature at a heating rate of 100 ° C./hour or less. If the heating rate exceeds 100 ° C./hour, melting may occur partially.
In the homogenization treatment, the time for maintaining the homogenization temperature (homogenization time) is preferably 4 hours or more and 10 hours or less. If the homogenization time is less than 4 hours, the homogenization may not proceed sufficiently. However, if the homogenization time is too long, there is no effect and the production efficiency is lowered. From the above viewpoint, the preferable homogenization time is in the range of 4 to 10 hours. Since the homogenization time is relatively long, this homogenization treatment is usually performed by placing it in a batch type furnace.
"Soaking heat treatment"
In this embodiment, after the homogenization treatment, the face cut body is further cooled to 500 to 555 [deg.] C., and after soaking for a predetermined time, hot rolling is started. The holding time (soaking time) in the temperature range of 500 to 555 ° C. is desirably performed for 1 hour or more.

"Hot rolling"
The hot rolling includes hot rough rolling and subsequent hot finish rolling. In the present embodiment, it is preferable to perform hot finish rolling using a single-mill reverse hot finish rolling mill.
In the hot rolling process, as shown in FIG. 1, after hot rough rolling to a thickness of about 20 mm using a hot rough rolling machine 20, a thickness of 2 to 3 using a hot finish rolling mill 30. Hot-roll to 6 mm.

The hot roughing mill 20 shown in FIG. 1 includes, for example, upper and lower work rolls 21 and 22, backup rolls 23 and 24, and transport paths 4 and 6 in which a plurality of transport rollers are arranged, and has been transported aluminum. This is an apparatus for rolling an alloy plate 5 to a desired thickness by passing between work rolls 21 and 22.
In FIG. 1, a hot rough rolling machine 20 is obtained by repeatedly supplying aluminum sheet 5 between the work rolls 21 and 22 and sequentially rolling them from the conveying paths 4 and 6 on the left and right sides of the work rolls 21 and 22. Can roll the plate 5 to a required thickness to form a plate 7.

  The hot finish rolling mill 30 shown in FIG. 1 is a single-mill reverse hot finish rolling mill, for example, upper and lower work rolls 31 and 32 and backup rolls 33 and 34 and installed on the entrance side of these rolls. A reel-type delivery winding device 35 and a reel-type delivery winding device 36 installed on the outlet side are provided. The hot finish rolling mill 30 is configured to wind a sheet material that is hot-rolled from the feed winder 35 and passed between the work rolls 31 and 32 by the feed winder 36, and from the feed winder 36. The operation of winding the sheet material hot-rolled by passing between the work rolls 31 and 32 again with the feed winder 35 is repeated as many times as necessary, and the interval between the work rolls 31 and 32 is gradually adjusted for each rolling operation. By doing so, it is an apparatus that hot-rolls an aluminum alloy plate material to a target plate thickness.

After the soaking process, the slab taken out from the soaking furnace usually starts hot rough rolling immediately, but if the slab temperature does not become less than 500 ° C., the start of hot rough rolling may be delayed. The number of hot rough rolling passes depends on the ingot (slab) thickness, finished thickness, slab width, alloy composition, and the like, but is generally in the range of tens of passes to tens of passes.
In the hot rough rolling, while the rolled material is thick, rolling is usually performed using a one-stand type rough rolling mill (hot rough rolling mill 20 shown in FIG. 1) in which a conveyance table is installed before and after the rolling mill. However, if the plate is thinned, the necessary transfer table length is increased, the slack due to the weight of the plate is increased, and the plate is likely to be cooled.

  Therefore, in order to hold on the transfer table, the plate thickness needs to be more than 10 mm. Therefore, the minimum plate thickness when the plate is sent from the roughing mill to the finishing mill depends on the coil weight and the plate width, but in the case of the weight and width used industrially, it is about 16 mm or more. preferable. Moreover, when the plate | board thickness at the time of sending to a finishing mill from a rough mill is too thick, the increase in the number of rolling passes in a finishing mill will be caused, and productivity will be reduced. Therefore, it is preferable that the upper limit of the sheet thickness at the time of sending to a finishing mill is 40 mm or less. When the aluminum alloy sheet is thinned from the above upper limit to the lower limit, hot finish rolling is performed with a single mill reverse hot finish rolling mill having the configuration shown in FIG.

Hot finish rolling is performed using a single-mill reverse hot finish rolling mill.
By using a single-mill reverse hot finish rolling mill (hot finish rolling mill 30 shown in FIG. 1) having a winding device on both sides of the rolling mill, the hot finish plate thickness can be reduced.
Therefore, since the reduction ratio of the subsequent cold rolling can be reduced, the number of cold rolling passes can be reduced and the productivity can be improved. On the other hand, for example, when a hot finish rolling mill in which the winding device is installed only on one side is used, there is a minimum value for the plate thickness that can be held on the transfer table, so that it can be rolled by hot rolling. The minimum plate thickness will increase. For this reason, the cold rolling reduction after hot rolling increases.

  As described above, the reduction in the thickness of the finished sheet of hot rolling contributes to the improvement of productivity by reducing the number of cold rolling passes. Therefore, in this embodiment, it is preferable that the finishing plate thickness of the hot finish rolling is in the range of 2.0 to 3.6 mm. If the finished sheet thickness is less than 2.0 mm, the cold rolling reduction ratio is insufficient, and a low ear ratio cannot be obtained. If the finished plate thickness exceeds 3.6 mm, the number of cold rolling passes increases and productivity decreases.

"Cold rolling"
Next, cold rolling is performed on the plate material after hot rolling so that the final cold rolling reduction is within a range of 76 to 95%. By setting the reduction ratio of the final cold rolling within the range of 76 to 95%, the necessary mechanical properties, in particular, the proof stress after the coating baking process are within a suitable range, and anisotropy and neck forming in can molding. There is an effect that sex is obtained in a well-balanced manner.
When the reduction ratio of the final cold rolling is less than 76%, work hardening by can molding proceeds and neck formability deteriorates.
If the rolling reduction of cold rolling exceeds 95%, the processing rate becomes excessive and the anisotropy deteriorates, and the strength of the plate material becomes too high, and there is a possibility that the DI formability described later is impaired.
By cold rolling, an aluminum alloy plate for beverage cans having a plate thickness of 0.210 to 0.470 mm can be obtained. Moreover, it is preferable that this aluminum alloy plate has the yield strength after baking by coating in the range of 230 to 320 N / mm ² .

“One or two intermediate annealings during cold rolling”
In the intermediate annealing step, a continuous annealing apparatus having a basic configuration shown in FIG. 2 is used for the plate during the cold rolling, and the heating rate is in the range of 10 to 200 ° C./second (10 ° C./second or more, 200 ° C./second). The following range) is heated, held at a holding temperature of 300 to 540 ° C. (300 ° C. or higher and 540 ° C. or lower) for 5 to 60 seconds, and then cooled at a cooling rate of 10 to 200 ° C./second. To do.
This intermediate annealing step brings the aluminum alloy sheet material into a semi-softened state, and it is preferable that the yield strength after annealing; YS (Yield Strength) is in a suitable range.
When the annealing temperature is less than 300 ° C., the softening is insufficient and there is a problem that cold working is liable to occur. If the annealing temperature exceeds 540 ° C. or the holding time exceeds 60 seconds, the solid solubility of the solute element becomes excessive, the mechanical properties of the final product become high, and the neck moldability of the beverage can deteriorates. Further, when the holding time exceeds 60 seconds, the productivity is lowered.

  FIG. 2 shows an example of the basic configuration of a continuous annealing device (Continuous Annealing Line: CAL). The continuous annealing device 40 in this example draws a long aluminum alloy plate 42 from a supply roll 41 and cushions 43. Is supplied to a long furnace body 44 having a length of several tens to 100 m, and is annealed under the above-mentioned conditions while moving in the furnace body 44. It is an apparatus that can be wound around a roll 47. According to this continuous annealing apparatus 40, since the aluminum alloy plate 42 passing through the furnace body 44 can be continuously processed alone, the intermediate annealing process is performed under more accurate heating and cooling conditions than the batch type annealing furnace. Can do.

  And if it is the continuous annealing apparatus 40, even if the width | variety and diameter of the coil of the state which wound the aluminum alloy board | plate material 42 around the supply roll 41 differ, in other words, the width | variety and thickness of the aluminum alloy board | plate material 42, and the length which should be processed Even if the lengths are different, annealing can be performed in the order in which they are to be manufactured. Can be suppressed.

"Final stabilization annealing"
Final stabilization annealing is performed after final cold rolling. The final stabilization annealing is desirably performed under conditions of a temperature increase rate of 3 ° C./min or more, a holding temperature of 120 to 140 ° C., a holding time of 1 to 2 hours, and a cooling rate of 10 ° C./min or more after the final cold rolling.
If the rate of temperature increase is less than 3 ° C./min, trace elements may be precipitated at the grain boundaries, and the aluminum alloy plate may be locally defective in processing.
If the holding temperature is less than 120 ° C, a sufficient effect may not be obtained and the formability of the aluminum alloy plate may be poor. If the holding temperature exceeds 140 ° C, the precipitation becomes excessive and the formability of the aluminum alloy plate is poor. There is a risk.
If the holding temperature is less than 1 hour, the formability of the aluminum alloy plate may be poor, and if the holding temperature exceeds 2 hours, the productivity is lowered.
If the cooling rate is less than 10 ° C./min, trace elements may be precipitated at the crystal grain boundaries of the aluminum alloy plate, and there is a possibility that local processing defects may occur.
By performing final stabilization annealing, local moldability such as can bottom molding can be improved, and molding abnormalities can be effectively suppressed.

Below, the outline | summary of the process and DI can which manufacture a DI can using the above-mentioned aluminum alloy plate are demonstrated.
FIG. 3 is a process diagram of a method for manufacturing a DI can, and FIG. 4 is a partial cross-sectional view showing the DI can. In these drawings, reference numeral 10 indicates the DI can.
The DI can 10 is a bottomed cylindrical DI can made of an aluminum alloy, and an iron alloy plate material having a thickness of 0.210 mm or more and 0.470 mm or less has an ironing ratio of 54.2% or more and 64. For example, the size in the can axis direction, that is, the height is about 122.5 mm, and the outer diameter is 65 mm or more and 67 mm or less. The body portion has a wall thickness of 0.095 mm to 0.110 mm, a tensile strength of 340 MPa to 410 MPa, and a can body weight of 11.6 g or less.

Further, as shown in FIG. 4, the bottom portion 12 includes a dome portion 12 a that is recessed inward in the can axis direction of the trunk portion 11, and an outer peripheral edge portion of the dome portion 12 a is in the can axis direction of the trunk portion 11. It is set as the annular convex part 12c which protrudes toward the outer side. The top of the annular convex portion 12c in the can axis direction is a grounding portion 12b that contacts the grounding surface L when the DI can 10 is placed on the grounding surface L so that the DI can 10 is in an upright posture. .
In addition, the DI can 10 is made by printing and painting the outer surface of the body portion 11 including a printed portion such as character information using a polyester-based paint, and the DI can 10 subjected to the outer surface printing and the outer surface coating is 180 ° C. After forming a 50 mg / dm ² coating film by heating for 30 seconds, the inner surface of the DI can 10 was coated with an epoxy-based paint and heated to 200 ° C. for 60 seconds to be 40 mg / dm ² The outer surface printing, the outer surface coating, and the inner surface coating in which the above coating film is formed are performed.

This DI can is manufactured by the following processes, for example.
A disc-shaped plate material (0 blank) W shown in FIG. 3 having a diameter of about 150 mm is formed by punching the aluminum alloy plate obtained in the above-described process.
Next, the plate material W is drawn into a cup-shaped body W1 by drawing with a cupping press.
Subsequently, the DI processing apparatus performs redrawing and ironing on the cup-shaped body W1 to form a bottomed cylindrical body W2. In this case, the ironing rate is, for example, 60.4%, and the ironing process is performed until the thickness of the thinnest portion of the body portion 11 becomes 0.100 mm.

  The DI processing apparatus used for the redrawing ironing process includes a single redrawing die having a circular through hole for redrawing processing, and a plurality of sheets having circular through holes arranged coaxially with the redrawing die ( For example, three ironing dies (ironing dies) are coaxial with the ironing die, and can be fitted into the through holes of the respective ironing dies, and are movable in the axial direction. A cylindrical punch sleeve and a cylindrical cup holder sleeve fitted to the outside of the punch sleeve are provided.

  In the redrawing process by the DI processing apparatus, the cup W1 is disposed between the punch sleeve and the redrawing die, the cup holder sleeve and the punch sleeve are advanced, and the cup holder sleeve is moved to the end face of the redrawing die. The punch sleeve pushes the cup W1 into the through hole of the redraw die while pressing the bottom surface to perform the cup pressing operation. As a result, a redrawn cup having a predetermined inner diameter is formed. Subsequently, the redrawn cup is passed through a plurality of ironing dies one after another and gradually ironed, and the side wall of the cup-shaped body is squeezed to extend the side wall to increase the side wall height and wall thickness. To form a bottomed cylindrical body W2.

The bottomed cylindrical body W <b> 2 that has been subjected to the ironing process has its bottom formed, for example, in a dome shape by the punch sleeve further pushing forward and pressing the bottom against the bottom molding die.
The bottomed cylindrical body W2 is cold-worked and hardened by the side walls being squeezed to increase the strength.

Next, the open end W2a of the bottomed cylindrical body W2 is trimmed.
Since the opening end W2a of the bottomed cylindrical body W2 formed by the DI processing apparatus is uneven and has a concavo-convex shape that undulates in the can axis direction, the opening end W2a of the bottomed cylindrical body W2 is By cutting and trimming, the height of the side wall in the can axis direction is made uniform over the entire circumference.
In this way, the DI can 10 having a circular cross section having the body 11 and the bottom 12 can be formed.

If it is the aluminum alloy plate obtained by the above-mentioned manufacturing method, even when it is subjected to ironing in the above-mentioned DI can manufacturing method, it can be made excellent in neck formability, such as scratches and molding defects. An aluminum can that does not cause problems can be obtained.
Moreover, if it is the aluminum alloy plate obtained by the above-mentioned manufacturing method, the aluminum can which improved the intensity | strength in the can axial direction of a neck part, in other words bottom buckling tolerance, can be obtained.

EXAMPLES Hereinafter, although an Example is shown and it demonstrates further in detail about the manufacturing method of the aluminum alloy plate for drink cans concerning this invention, this invention is not limited to a following example.
Aluminum alloys having the compositions shown in Tables 1 and 2 were melted, degassed and filtered with molten metal, and then cast into a slab having a thickness of 600 mm, a width of 1100 mm, and a length of 4.5 m by semi-continuous casting.

Next, after chamfering the slab, using a homogenizing and soaking furnace, a homogenization treatment is performed at a holding temperature of 565 ° C. and a holding time of 6 hours, and then cooled in the furnace to a holding temperature of 520 ° C., A soaking treatment was performed at the holding temperature for a holding time of 1 hour.
Subsequently, hot rough rolling is performed at 430 ° C. up to a plate thickness of 20 mm using the hot rough rolling mill 20 having the configuration shown in FIG. 1, and then the single mill reverse hot finish rolling mill 30 shown in FIG. 1 is used. And the aluminum alloy sheet material of the finishing board thickness shown in Table 1 and Table 2 was obtained by hot finish rolling.
As shown in Tables 1 and 2, the outlet temperature of the hot rough rolling was set to 430 ° C.

Next, after subjecting the aluminum alloy sheet after hot rolling to first cold rolling with a reduction rate of 0 to 20%, holding temperatures shown in Tables 3 and 4 using a continuous annealing apparatus having the configuration shown in FIG. First intermediate annealing (CAL) was performed under the condition of holding time.
Next, the aluminum alloy sheet after the first intermediate annealing was subjected to final cold rolling at the rolling reductions (77 to 97%) shown in Tables 3 and 4, and beverage cans having the plate thickness (mm) shown in Tables 3 and 4 An aluminum alloy plate was obtained.
The samples No. 10 and 11 were subjected to the first cold rolling (reduction rate 61%), the second cold rolling (reduction rate 20%), and the final cold rolling (reduction rate 77%). In the meantime, intermediate CAL was applied twice to obtain an aluminum alloy sheet.

The obtained aluminum alloy plate for a can body was subjected to a heat treatment equivalent to painting baking under the conditions of 210 ° C. × 10 minutes, and the proof strength after baking (AB proof strength, 0.2% proof strength) was measured.
About the obtained blank material of the aluminum alloy plate for can bodies, it processed into the drink can of capacity 350cc by DI process demonstrated based on FIG.

"Anisotropy (ear rate)"
As anisotropy evaluation of the obtained aluminum alloy plate for can bodies, the ear rate in cup molding was measured.
The ear rate was calculated from the height of the side wall of the cup that was deep-drawn from the Eriksen testing machine. The processing conditions were punch diameter: 33 mm (flat head punch), drawing ratio: 1.75, wrinkle holding force: 3 kN. The side wall height of this cup was measured with a digital micrometer, and the ear rate was calculated by the following formula.
(Mountain average height-average valley height) ÷ average valley height x 100 = ear rate (%)
The average height of the 0 ° and 180 ° peaks and the average height of the 45 °, 135 °, 225 °, and 315 ° peaks were determined, and the higher one was defined as the average height of the above equation. In addition, the average valley heights of 90 ° and 270 ° were obtained and used as the average valley height of the above formula.
As an evaluation of anisotropy by the ear ratio, the average value of n = 3 is less than 2.5% as “◯”, 2.5 to 3.5% as “△”, and samples exceeding 3.5 as “×” Was determined.

"Neck formability"
The neck formability was evaluated by DI molding of 350cc beverage cans for all samples. After the DI molding, the mouth end of the can was removed by trim, washed and dried, and coated and printed on the inner and outer surfaces of the can, followed by die neck molding and spin flow molding to form a neck shape of a 350 cc beverage can having an inner diameter of approximately 55 mm. In addition, during the DI molding, the thickness of the portion subjected to the neck molding process was thinned to evaluate the generation of wrinkles at the flange tip in the neck molding process. 24 cans of each sample were made, the degree of wrinkles at the flange tip was visually evaluated, and “○” indicates that no wrinkles were observed or very slight wrinkles were observed, and many extremely small wrinkles were observed. Or the thing where wrinkles were recognized clearly was made into "x".

"Buckling strength"
The buckling strength is measured by measuring the strength of the can in the axial direction of the can, and “○” indicates that no buckling occurred when a load equivalent to 1.2 times the load when the cap was tightened was applied. The thing which generate | occur | produced was evaluated as "x".
"DI moldability"
The DI moldability was evaluated as “◯” when no can barrel breakage occurred at the time of continuous production of 1,000 cans, and “×” when one or more cans occurred.
"Bottom moldability"
The bottom moldability was evaluated as “◯” when no cracks or breakage of the bottom peripheral part occurred at the time of continuous production of 1,000 cans, and “×” when one or more cans occurred.
The above results are shown in Tables 1 to 4 below.

  As shown in Tables 1 and 3, the examples of Nos. 1 to 21 are alloy components, homogenization temperature, soaking temperature, hot rough rolling temperature, hot finish rolling temperature, hot finish rolled sheet thickness, Number of intermediate CALs, intermediate CAL temperature, intermediate CAL time, final cold rolling rate (final cold rolling rate), rate of temperature increase during stabilization annealing, holding temperature during stabilization annealing, holding time during stabilization annealing, stable This is an aluminum alloy plate manufactured with the cooling rate at the time of chemical annealing and the final plate thickness within the desired ranges, respectively. Examples Nos. 1 to 21 are aluminum alloy plates having excellent AB yield strength, little anisotropy, excellent neck formability, high buckling strength, and excellent DI formability and bottom formability. there were.

The comparative sample of No. 22 abbreviate | omitted implementation of intermediate | middle CAL, and other conditions are the samples manufactured on the conditions equivalent to an Example, but the anisotropy deteriorated.
The comparative sample of No. 23 was manufactured by setting the temperature of the intermediate CAL lower than the lower limit of 300 ° C., which is a desirable condition, but the anisotropy deteriorated.
The comparative sample of No. 24 is a sample manufactured by setting the temperature of the intermediate CAL higher than the upper limit of 540 ° C., which is a desirable condition, but the AB proof stress was too high. When AB yield strength is too high, DI moldability and neck moldability will fall.
The comparative sample of No. 25 is a sample manufactured by setting the intermediate CAL time to be longer than the upper limit of 60 seconds, which is a desirable condition. This sample had too high AB yield strength, and DI moldability and neck moldability deteriorated.

The comparative sample of No. 26 was a sample in which the rate of temperature increase during stabilization annealing was lower than the lower limit of 3 ° C./min, but the bottom moldability was lowered.
The comparative sample of No. 27 was a sample in which the cooling rate during the stabilization annealing was lower than the lower limit of 10 ° C./min, but the bottom moldability was lowered.
The comparative sample of No. 28 was a sample in which the holding temperature during the stabilization annealing was lower than the lower limit of 120 ° C., but the bottom moldability was lowered.
The comparative sample of No. 29 was a sample in which the holding temperature during the stabilization annealing was higher than the upper limit of 140 ° C., but the bottom moldability was lowered.

The comparative sample of No. 30 was a sample in which the holding time during the stabilization annealing was shorter than the lower limit of 1 hour, but the bottom moldability was lowered.
The comparative sample of No. 31 is a sample in which the hot rolled finish plate thickness is thicker than the upper limit of the desired plate thickness of 3.6 mm and the final cold rolling rate exceeds the upper limit of the desired range. And there was a problem with neck formability.
The comparative sample of No. 32 is a sample containing Si exceeding the upper limit of 0.35% by mass of the desired Si content of the aluminum alloy plate, but the AB yield strength becomes too high, and there is a problem in neck formability and DI formability. occured.
The comparative sample of No. 33 is a sample containing Fe that is less than the lower limit of 0.35% by mass of the desirable Fe content of the aluminum alloy plate, but has a problem in DI formability.

The comparative sample of No. 34 is a sample containing Fe that exceeds the upper limit of 0.55% by mass of the upper limit of the desirable Fe content of the aluminum alloy plate, but has a problem in neck formability and DI formability.
The comparative sample of No. 35 was a sample containing less Cu than the lower limit of 0.15% by mass of the desirable Cu content of the aluminum alloy plate, but the AB yield strength was insufficient, causing a problem in buckling strength.
The comparative sample of No. 36 was a sample containing more Cu than the upper limit of 0.48 mass% of the desirable Cu content of the aluminum alloy plate, but it caused problems in neck formability and DI formability.

The comparative sample of No. 37 was a sample containing less than 0.8% by mass of the lower limit of the desirable Mn content of the aluminum alloy plate, but it caused a problem in DI formability.
The comparative sample of No. 38 is a sample containing Mn that is higher than the upper limit of 1.15% by mass of the desirable Mn content of the aluminum alloy plate, but has a problem in neck formability.
The comparative sample of No. 39 was a sample containing less Mg than the lower limit of 0.6% by mass of the desirable Mg content of the aluminum alloy plate, but the AB yield strength was insufficient, causing a problem in buckling strength.
The comparative sample of No. 40 is a sample that contains more Mg than the upper limit of 1.6% by mass of the desirable Mg content of the aluminum alloy plate, but it caused problems in neck formability and DI formability.

  From the above results, in order to obtain an aluminum alloy plate for beverage cans having excellent AB yield strength, low anisotropy, excellent neck formability, high buckling strength, and excellent DI formability and bottom formability. Set the alloy composition, hot finish rolled sheet thickness, intermediate CAL count, intermediate CAL temperature, intermediate CAL time in the desired range, and set the heating rate, holding temperature, holding time, and cooling rate during stabilization annealing. It can be seen that it is important to set the respective desired ranges.

  W ... Blank material, W1 ... Cup, W2 ... Can body, W2a ... Open end, 4, 6 ... Conveyance path, 5, 7 ... Plate material, 10 ... DI can, 11 ... Body, 12 ... Bottom, 12a ... Dome Part, 12b ... grounding part, 12c ... annular convex part, 13 ... neck part, 14 ... flange part, 20 ... hot rough rolling mill, 21, 22 ... work roll, 23, 24 ... backup roll, 30 ... hot finish Rolling mills 31, 32 ... work rolls, 33, 34 ... backup rolls, 35, 36 ... delivery winding device, 40 ... continuous annealing device, 41 ... supply roll, 42 ... aluminum alloy sheet, 43, 46 ... shock absorber, 44 ... furnace body, 47 ... winding roll.

Claims (3)

In mass%, Si: 0.35% or less, Fe: 0.35-0.55%, Cu: 0.15-0.48%, Mn: 0.8-1.15%, Mg: 0.60 An ingot obtained by melting an aluminum alloy containing ˜1.60%, the balance consisting of Al and inevitable impurities, and semi-continuous casting is homogenized and then subjected to soaking and hot rough rolling. When producing aluminum alloy plates for beverage cans through hot finish rolling and cold rolling,
In the course of cold rolling, continuous annealing is performed once or twice using a continuous annealing apparatus and held at a temperature of 300 to 540 ° C. for 5 to 60 seconds,
After the final cold rolling, the final stabilization annealing is performed under the conditions of a heating rate of 3 ° C./min or more, a holding temperature of 120 to 140 ° C., a holding time of 1 to 2 hours, and a cooling rate of 10 ° C./min or more.
A method for producing an aluminum alloy plate for beverage cans having excellent bottom formability and bottom portion strength, characterized by obtaining an aluminum alloy plate having a plate thickness of 0.210 to 0.470 mm and a proof stress of 230 to 320 N / mm ² after painting and baking. .   The homogenization treatment performed on the ingot is performed under the condition of heating at 555 to 605 ° C. for 4 to 10 hours, the soaking is performed under the condition of heating at 500 to 555 ° C. for 1 hour or more, and the outlet temperature is set to 400 to 460. Hot rough rolling is performed at a temperature set to ℃, the finishing plate thickness is set to 2.0 to 3.6 mm, the finishing temperature is set to 240 to 360 ℃, the hot finish rolling is performed, and the final cold rolling rate The manufacturing method of the aluminum alloy plate for drink cans which is excellent in the bottom moldability and bottom part intensity | strength of Claim 1 characterized by performing cold rolling by setting 76 to 95%.   In addition to the above composition, an aluminum alloy containing at least one or more of Cr: 0.05% or less, Zn: 0.25% or less, Ti: 0.10% or less is used. The manufacturing method of the aluminum alloy plate for drink cans which is excellent in the bottom moldability and bottom part intensity | strength of Claim 1 or Claim 2 characterized by these.

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