JP5289701B2 - Aluminum alloy plate for cap and method for producing the same - Google Patents

Description

  The present invention relates to an aluminum alloy plate for a cap of a bottle can and a method for producing the same.

  Threaded caps are widely used as caps for glass bottles and plastic containers. Recently, aluminum alloy bottle cans with threaded caps have also been developed. As a material for such a bottle can, for example, an Al—Mn-based aluminum alloy such as JIS3004 (AA3004) or JIS3104 (AA3104) is used. On the other hand, as a material for the cap, for example, an Al—Mg-based aluminum alloy such as JIS5154 is used (see, for example, Patent Documents 1 to 3).

  The quality characteristics required for bottle caps are diverse, including pressure resistance, corrosion resistance, low ear, sealing properties, explosion-proof properties, and deep drawability, and these properties must be stable. . Further, since this type of cap is mass-produced, it is desirable that no material is wasted during manufacture. For example, when forming a cap by deep drawing, how much ears are wasted of materials depending on the composition and manufacturing conditions of the aluminum alloy plate, and how good the workability is with a low ear rate An important issue is whether high tensile strength can be secured.

  By the way, since the bottle can provided with the screwed cap can be closed again after opening the cap, it is very convenient. However, when the bottle can is left with the contents remaining, the germs mixed in the bottle can grow to generate gas in the bottle can and increase the internal pressure of the bottle can. Therefore, in such a case, it is necessary that the screw portion of the cap has a strength that can withstand the increase in the internal pressure of the bottle can so that the cap does not come off and the content does not jump out. On the other hand, a structure in which a slit is formed in the knurl portion of the cap and gas is released from the slit has been proposed.

Recently, bottles for hot beverages have also been developed. In this hot beverage bottle can, the internal pressure of the bottle can rises due to the heated contents, so in this case as well, the cap should be heat resistant so that the cap will not deform and the contents will not pop out during heating. It is necessary to keep. In addition, when the content of the bottle can is a carbonated beverage or the like, the pressure in the bottle can is usually about 0.2 MPa, but there is also a knowledge that a higher pressure is generated depending on the use environment, temperature conditions, and the like. Therefore, it is important to produce a cap made of an aluminum alloy plate excellent in heat resistance for a cap used in such a hot beverage bottle can.
JP 2005-2464 A JP 2004-353079 A JP 2005-126664 A

  The present invention has been proposed in view of such conventional circumstances, and it is intended to improve heat resistance of caps used for bottles for hot beverages and the like, and has excellent mechanical properties and moldability. An object of the present invention is to provide an Al—Mn-based aluminum alloy plate for a cap that satisfies the requirements and a method for producing the same.

In order to achieve this object, the invention according to claim 1 is, in mass%, Mn: 0.5 to 1.3%, Mg: 0.5 to 0.8 %, Si: 0.01 to 0 .6%, Fe: 0.1-0.7%, Cu: 0.01-0.2%, Zn: 0.3-0.4% , Ti: 0.2% or less, Cr: 0.3 %, With a balance of Al and inevitable impurities, a tensile strength of 185 to 245 MPa, a proof stress of 150 to 180 MPa, an elongation of 4 to 7%, and an ear ratio at a drawing ratio of 1.97 Is obtained by hot rolling and cold rolling from a slab having the above composition, and the final cold rolling rate is 35 to 75%, and the final annealing is performed at 220 to 230 ° C. It is the aluminum alloy plate for caps characterized.

The invention as set forth in claim 2 is characterized in that, in the aluminum alloy plate for a cap according to claim 1 , the rate of change in tensile strength before and after baking is 5% or less.
The invention according to claim 3, in mass%, Mn: 0.5~1.3%, Mg : 0.5~0.8%, Si: 0.01~0.6%, Fe: 0. 1 to 0.7%, Cu: 0.01 to 0.2%, Zn: 0.3 to 0.4% , Ti: 0.2% or less, Cr: 0.3% or less, the balance Al And a composition consisting of inevitable impurities, a tensile strength of 185 to 245 MPa, a proof stress of 150 to 180 MPa, an elongation of 4 to 7%, and an ear ratio at a drawing ratio of 1.97 of 2% or less. A method for producing an aluminum alloy plate, in which a slab having the above composition is hot-rolled and cold-rolled to have a final cold rolling rate of 35 to 75% and subjected to stabilization annealing at 220 to 230 ° C. after the final cold rolling. It is characterized by that.
Invention of Claim 4 is a manufacturing method of the aluminum alloy plate for caps of Claim 3 , Comprising: As the aluminum alloy plate for caps, the aluminum alloy for caps of 5% or less of the change rate of the tensile strength before and behind baking It is characterized by obtaining a board.

  As described above, according to the present invention, since it has good mechanical strength as an Al-Mn cap material having excellent heat resistance, it can be used in bottles for hot beverages. It is possible to prevent the cap from being lifted or deformed due to an increase in the internal pressure of the can. In addition, because it has good elongation, it has excellent workability, and furthermore, the ear rate can be lowered while satisfying these mechanical properties, so that waste of materials at the time of production is reduced and low when mass-produced. Cost reduction can be realized.

  Hereinafter, an aluminum alloy plate for a cap to which the present invention is applied and a manufacturing method thereof will be described in detail.

First, an aluminum alloy plate for a cap to which the present invention is applied will be described.
The aluminum alloy plate for a cap to which the present invention is applied is in mass%, Mn: 0.5 to 1.3%, Mg: 0.3 to 1.0%, Si: 0.01 to 0.6%, Fe : 0.1 to 0.7%, Cu: 0.01 to 0.2%, Zn: 0.5% or less, Ti: 0.2% or less, Cr: 0.3% or less, the balance Al And a composition comprising inevitable impurities, a tensile strength of 185 to 245 MPa, an elongation of 4% or more, and an ear ratio at a drawing ratio of 1.97 of 2% or less.

  Hereinafter, the reasons for defining each composition element added to the aluminum alloy plate for a cap of the present invention and the amount of addition and the specific matters of the aluminum alloy of the present invention will be described.

(Mn: 0.5 to 1.3%)
Mn is an element necessary for improving the strength of the aluminum alloy. However, if it is less than 0.5%, the effect of improving the strength of the aluminum alloy becomes insufficient. Deteriorates. Therefore, it is preferable to contain Mn in the range of 0.5 to 1.3%, and more preferably in the range of 0.7 to 1.1%.

(Mg: 0.3-1.0%)
Mg is an element necessary for improving the strength of the aluminum alloy together with Mn, but if it is less than 0.3%, the effect of improving the strength of the aluminum alloy becomes insufficient, and if it exceeds 1.0% , Workability deteriorates. Therefore, Mg is preferably contained in the range of 0.3 to 1.0%, more preferably in the range of 0.5 to 0.8%.

(Si: 0.01-0.6%)
Si is an element that improves workability, but if it is less than 0.01%, the effect of improving workability is small, and if it exceeds 0.6%, workability deteriorates conversely. Therefore, Si is preferably added in the range of 0.01 to 0.6%, more preferably in the range of 0.25 to 0.45%.

(Fe: 0.1-0.7%)
Fe is an element that improves the strength of the aluminum alloy, but if it is less than 0.1%, the effect of improving the strength is small, and if it exceeds 0.7%, the workability deteriorates. Therefore, Fe is preferably added in the range of 0.1 to 0.7%, more preferably in the range of 0.3 to 0.5%.

(Cu: 0.01-0.2%)
Cu is an element that improves the strength of the aluminum alloy, but if it is less than 0.01%, the effect of improving the strength is small, and if it exceeds 0.2%, the corrosion resistance decreases. Therefore, Cu is preferably added in a range of 0.01 to 0.2%, more preferably in a range of 0.05 to 0.1%.

(Zn: 0.5% or less)
Zn is an element that refines crystal grains and improves formability. However, if it exceeds 0.5%, the strength of the aluminum alloy becomes too high and the formability deteriorates. Therefore, Zn is preferably added in the range of 0.5% or less, more preferably in the range of 0.3 to 0.4%.

(Ti: 0.2% or less)
Ti is an element that attempts to refine crystal grains and improve formability. However, if it exceeds 0.2%, the surface state of the aluminum alloy deteriorates due to rough skin. Therefore, Ti is preferably added in the range of 0.2% or less, more preferably in the range of 0.05 to 0.1%.

(Cr: 0.3% or less)
Cr is an element that reduces the ear ratio, but if it exceeds 0.3%, the strength of the aluminum alloy becomes too high, and the formability deteriorates. Therefore, Cr is preferably added in a range of 0.3% or less, more preferably in a range of 0.1 to 0.2%.

(mechanical nature)
The aluminum alloy plate for a cap of the present invention preferably has a tensile strength of 185 to 245 MPa and an elongation of 4% or more.
When the tensile strength is less than 185 MPa, the strength as a cap for a bottle can is insufficient, and when it exceeds 245 MPa, it is difficult to mold a screw portion formed on the cap. Therefore, the tensile strength is preferably in the range of 185 to 245 MPa, more preferably in the range of 190 to 220 MPa.
If the elongation is less than 4%, the moldability of the cap by deep drawing will deteriorate. Therefore, the elongation is preferably 4% or more, and more preferably in the range of 4.0 to 7.0%.

  Moreover, it is preferable that the proof stress of the aluminum alloy plate for caps of this invention is 140-210 MPa. When the proof stress is less than 140 MPa, appearance defects such as wrinkles are likely to occur during deep drawing, and when it exceeds 210 MPa, cracks are likely to occur during deep drawing. Therefore, the proof stress is preferably in the range of 140 to 210 MPa, more preferably in the range of 150 to 180 MPa.

(Deep drawing test)
The aluminum alloy plate of the present invention preferably has an ear ratio of 2% or less at a drawing ratio of 1.97. By making the ear rate 2% or less, it is possible to reduce the waste of materials during manufacturing. The ear rate was determined by performing a deep drawing test using a die having a die diameter of 33.7 mm, a punch diameter of 33 mm, and a punch shoulder R4 mm under the conditions of a blank diameter of 65 mm and a drawing ratio of 1.97. Calculated from the above.

Next, the manufacturing method of the aluminum alloy plate for caps which applied this invention is demonstrated.
The manufacturing method of the aluminum alloy plate for caps to which the present invention is applied can be manufactured by using an aluminum alloy having the above composition components and combining conventional methods applied when manufacturing this type of aluminum alloy. That is, after obtaining a slab from the molten metal, the slab is subjected to hot rolling and cold rolling a plurality of times, and before and after the rolling, homogenization treatment and intermediate annealing are performed as necessary, and further cooling is performed after the intermediate annealing. The rolling process is performed a plurality of times, and at that time, the cold rolling rate (referred to as the final cold rolling rate) from the last intermediate annealing is set to 35 to 75%, and stabilization annealing at 200 to 240 ° C. is performed after the final cold rolling. This is a feature of the present invention.

  Specifically, when the final cold rolling rate is less than 35%, the strength is insufficient, and when it exceeds 75%, the ear rate is increased. For example, the final cold rolling rate when processed from a thickness of 0.6 mm to 0.25 mm is 58%, and the final cold rolling rate when the thickness is changed from 0.8 mm to 0.25 mm is 69%. Even in the case, the tensile strength is improved when the ear rate is lower and the cold rolling rate is higher. Therefore, the final cold rolling rate is preferably in the range of 35 to 75%, and more preferably in the range of 60 to 70%. Thereby, tensile strength can be improved, maintaining a low ear rate.

  In many cases, caps for bottle cans are printed by baking (baking) a coating material for caps on the top surface of the cap. Therefore, in the aluminum alloy plate of the present invention, it is preferable to perform the stabilization annealing in the above-mentioned range of 200 to 240 ° C. so that the physical properties and the like do not change during baking. Specifically, if the stabilization annealing is less than 200 ° C., the physical properties and the like change during baking, and if it exceeds 240 ° C., the physical properties and the like change due to this heating. Therefore, the stabilization annealing is preferably performed in the range of 200 to 240 ° C, and more preferably in the range of 220 to 230 ° C. In addition, about a heating method, a batch type or a rapid heating system may be sufficient. The heating time is about 1 to 10 hours for the batch method and about 1 to 60 seconds for the rapid heating method.

  When the aluminum alloy plate of the present invention produced as described above has good mechanical strength as an Al-Mn-based cap material with excellent heat resistance, it is used for bottles for hot beverages, etc. In this case, it is possible to prevent the cap from being lifted or deformed due to an increase in the internal pressure of the bottle can. In addition, because it has good elongation, it has excellent workability, and furthermore, the ear rate can be lowered while satisfying these mechanical properties, so that waste of materials at the time of production is reduced and low when mass-produced. Cost reduction can be realized.

  In addition, the aluminum alloy plate of the present invention is not limited to the cap material of a bottle can for hot beverages, but can of course be used as an explosion-proof cap material that vents gas between the cap and the bottle mouth at high pressure. It can also be used for cap materials that do not require pressure resistance as the explosion-proof type, and the range of use as cap materials is very wide.

  Hereinafter, the effects of the present invention will be made clearer by examples. In addition, this invention is not limited to a following example, In the range which does not change the summary, it can change suitably and can implement.

  In this example, first, an aluminum alloy having each composition component shown in Table 1 was melted and cast into a slab. Next, homogenization treatment was performed at 560 ° C. for 4 hours, and the thickness was 6 mm by hot rolling. Next, cold rolling and intermediate annealing were performed in a continuous annealing furnace (460 ° C.), and cold rolling was performed at a final cold rolling rate shown in Table 2 to a final sheet thickness of 0.25 mm. And the stabilization annealing of 4 hours was performed at the temperature shown in Table 2, and No. 1-20 aluminum alloy plates were obtained.

And No. For the aluminum alloy plates of 1 to 20, the ear rate and the tensile strength, proof stress, and elongation before baking (AS) and after baking (AB) were measured. The measurement results are shown in Table 2.
The ear rate was determined by performing a deep drawing test using a die having a die diameter of 33.7 mm, a punch diameter of 33 mm, and a punch shoulder R4 mm under the conditions of a blank diameter of 65 mm and a drawing ratio of 1.97. Calculated from the above.

  As shown in Table 2, no. Each of the aluminum alloy sheets 1 to 4 (Examples) uses an aluminum alloy having the composition range of the present invention, the final cold rolling rate is 35 to 75%, and the final cold rolling is in the range of 200 to 240 ° C. Stabilized annealing is performed. These No. All of the aluminum alloy plates 1 to 4 exhibited good mechanical properties, with a tensile strength before baking of 185 to 245 MPa, a proof stress of 140 to 210 MPa, and an elongation of 4% or more. The rate of change in tensile strength before and after baking was also 5% or less. Moreover, the ear rate was 2% or less. On the other hand, no. 5-20 aluminum alloy plates (comparative examples) could not satisfy the mechanical properties of the present invention, and the ear rate could not be kept low.

Claims (4)

In mass%, Mn: 0.5 to 1.3%, Mg: 0.5 to 0.8 %, Si: 0.01 to 0.6%, Fe: 0.1 to 0.7%, Cu: 0.01-0.2%, Zn: 0.3-0.4% , Ti: 0.2% or less, Cr: 0.3% or less, and having a composition comprising the balance Al and inevitable impurities The tensile strength is 185 to 245 MPa, the proof stress is 150 to 180 MPa, the elongation is 4 to 7%, and the ear ratio at a drawing ratio of 1.97 is 2% or less.
An aluminum alloy for caps obtained from a slab having the above composition by hot rolling and cold rolling, and having a final cold rolling rate of 35 to 75% and subjected to stabilization annealing at 220 to 230 ° C. after the final cold rolling. Board. The aluminum alloy plate for a cap according to claim 1 , wherein the rate of change in tensile strength before and after baking is 5% or less. In mass%, Mn: 0.5 to 1.3%, Mg: 0.5 to 0.8 %, Si: 0.01 to 0.6%, Fe: 0.1 to 0.7%, Cu: 0.01-0.2%, Zn: 0.3-0.4% , Ti: 0.2% or less, Cr: 0.3% or less, and having a composition comprising the balance Al and inevitable impurities A method for producing an aluminum alloy plate for a cap having a tensile strength of 185 to 245 MPa, a proof stress of 150 to 180 MPa, an elongation of 4 to 7%, and an ear ratio of 2% or less at a drawing ratio of 1.97. ,
A slab having the above composition is hot-rolled and cold-rolled to have a final cold rolling rate of 35 to 75%, and subjected to stabilization annealing at 220 to 230 ° C. after the final cold rolling. Manufacturing method. The method for producing an aluminum alloy plate for a cap according to claim 3 , wherein an aluminum alloy plate for a cap having a tensile strength change rate of 5% or less before and after baking is obtained as the aluminum alloy plate for a cap.