JP2007153376A - Small-capacity threaded can made of aluminium alloy - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light weight and small-capacity threaded can made of an aluminium alloy which causes no problem in manufacturing. <P>SOLUTION: In forming the small-capacity threaded can, a roughly circular disk panel punched out from an aluminium alloy panel is at least processed for spinning and ironing for forming a tubular can with a bottom whose can bottom center 2 and can body 3 are integrally formed, an inclining shoulder 16 and a small-diameter tubular opening neck 17 are formed by reducing the diameter of the opening end side of the tubular can body 3 of the thinned tubular can with a bottom, and a threaded part 18 and a curl part 19 are formed on the part 17. The small-capacity threaded can is characterized in that the ratio (V/d) of a can internal volume V(ml) relative to the can body internal diameter d(mm) is 2.0-3.6, the relation (t1/t2) between the panel thickness t1 of the bottle can shaped can bottom center and the smallest wall thickness t2 of the bottle can shaped can body 3 is 1.5-2.0 and t2 is 0.17 mm or less. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention integrally forms the bottom of the can and the body of the can by drawing ironing, forms an inclined shoulder and a small-diameter cylindrical mouth and neck on the opening end side of the body, and a screw and a neck and neck on the mouth and neck. The present invention relates to a threaded can having a curled portion. In particular, the present invention relates to a small-capacity threaded can made of an aluminum alloy having a total internal volume of about 70 ml to 190 ml.

  Conventionally, small glass bottles have been used as containers used for the purpose of selling beverages whose contents are about 50 ml to 160 ml, such as drinks and health drinks. In such a glass bottle for selling small-volume beverages, the container is heavy when the content is small, and there is a problem that the container is easily damaged if dropped in the distribution process. Container was sought. As a container that meets such a purpose, there is an aluminum screw can formed by impact molding or the like (see Patent Document 1).

JP 2001-315745 A JP 2005-96843 A Japanese Patent Laid-Open No. 10-300653

  However, in the manufacture of a small-capacity threaded can, there is a problem that buckling or the like is more likely to occur than a large-capacity threaded can due to a molding load or a plugging load. In other words, in order to form a mouth neck and a shoulder having a diameter smaller than the can body diameter, when a diameter reduction process is performed by neck forming, a forming load is applied to the can body, and roll-on When the pilfer proof cap is wound around the mouth and neck by capping, a stoppering load is applied to press the cap against the container. These loads are applied to the can body, neck and neck. It concentrates on the part where the diameter of the can body changes between the shoulders and causes the depression of the shoulder and the buckling of the mouth and neck. In the case of an impact-molded screw can as described above, a relatively soft JIS1000 series aluminum alloy is used as the material. Since such an aluminum alloy is soft, the processability in impact molding is good, but the depression of the shoulder and the buckling of the mouth and neck are particularly likely to occur. Therefore, in order to secure a strength that does not cause problems such as buckling in the process of forming the threaded can, it is necessary to cope with it by increasing the wall thickness of the can body. For such a can body, thinning the can body for the purpose of reducing production costs may lead to a decrease in the buckling strength of the container and poor molding of the screw, making it difficult to reduce the weight and making it economical. There was an inferior problem.

  In contrast, a bottomed cylindrical can formed by drawing ironing is reduced in diameter to form a conical or dome-shaped inclined shoulder portion and a small-diameter cylindrical mouth-and-neck portion. There is a threaded can having a relatively large capacity by DI molding in which a thread part and a curl part are formed on the part (see Patent Document 2). However, manufacturing a small-capacity threaded can with a small can body diameter by applying such a DI-molded threaded can technique has not been performed for the following reasons. .

  In other words, a small-capacity threaded can requires a certain height of the can body when considering the ease of gripping and handling when opening and closing the cap. In comparison, the can body diameter is set smaller. In this case, if the outer diameter of the can body is reduced with the same wall thickness, the cross-sectional area of the can body wall in the cross section of the can body is correspondingly reduced, so the same load as that of the large capacity can is applied. In some cases, the acting stress increases and buckling is likely to occur. For this reason, it is necessary to increase the wall thickness to maintain the strength, and the can body cannot be reduced in weight by reducing the wall thickness of the can body.

  On the other hand, when a small-capacity screwed can is applied to a beverage container, the can body is clamped from both sides and the side wall of the can body is pushed in to check the sealing performance after filling the contents. There is a case where a contact pressure type internal pressure inspection is performed to inspect the internal pressure of the can body from the relationship between the amount of pressing of the body and the can body (Patent Document 3). In this case, if the wall thickness of the can body is thick, there is a problem that the measurement accuracy is deteriorated. In addition to the threaded can by impact molding, even if the threaded can by DI molding is thick, The contact pressure test could not be performed with high accuracy. Therefore, it has been difficult to adopt a small-capacity screwed can as a beverage container.

  The present invention has been made paying attention to the above technical problems, and in a small-capacity threaded can by squeezing and ironing, the dimensional configuration of the mouth and neck of the container, the shoulder, the can body, etc. By defining the thickness, even if the wall thickness of the can body is made thinner than before, buckling does not occur due to molding load or plugging load, and it is possible to perform contact pressure type internal pressure inspection with high accuracy. An object of the present invention is to provide a light weight small-capacity aluminum alloy threaded can that can easily hold a can body even when it is opened and closed.

  In order to achieve the above object, the invention of claim 1 is characterized in that a circular plate obtained by punching an aluminum alloy plate or a resin-coated aluminum alloy plate into a substantially circular shape is subjected to at least drawing and ironing, A bottomed cylindrical can formed integrally with the can body is molded, and the opening end side of the cylindrical can body of the bottomed cylindrical can that has been thinned is reduced in diameter to form an inclined shoulder and a small diameter. The ratio of the outer diameter D (mm) of the mouth and neck to the inner diameter d (mm) of the can body in a threaded can having a cylindrical mouth and neck formed with a threaded portion and a curled portion formed on the mouth and neck (D / d) is in the range of 0.53 to 0.80, the shoulder portion is in the form of a dome whose longitudinal section is an outwardly convex arc shape, and the can body height h is 50 mm to 100 mm. The ratio (V / d) of the total internal volume V (ml) to the inner diameter d (mm) of the can body is 2 0 to 3.6, the ratio (t1 / t2) of the thickness t1 of the center of the bottom of the can to the minimum wall thickness t2 of the can body is in the range of 1.5 to 2.0, and t2 Is a small-capacity screw can made of aluminum alloy, characterized by being 0.17 mm or less.

  The invention of claim 2 is the invention of claim 1, wherein the mouth and neck portion has an outer diameter of 28 mm or more, and a mouth from the connecting portion between the shoulder portion and the mouth and neck portion to the opening end of the mouth and neck portion. It is a can with a small capacity screw made of aluminum alloy characterized by having a neck height of 20 to 26 mm.

  The invention of claim 3 is the invention of claim 1 or 2, wherein the shoulder portion has a dome shape whose cross section is an outwardly convex arc shape, and the mouth neck portion and the shoulder portion are A tangential angle formed by a vertical line and a tangent line that is connected by a bent portion having a predetermined radius of curvature in a longitudinal section and that passes through a contact point between the shoulder portion and the bent portion and is in contact with an arc of the shoulder section is a screw. An aluminum alloy small-capacity screw-attached can characterized by having a shoulder shape of 30 ° to 60 ° with the attached can upright.

  According to a fourth aspect of the present invention, in the first to third aspects of the present invention, the can bottom portion of the threaded can includes a grounding portion whose diameter is smaller than the can body diameter, and an inclined portion that connects the grounding portion and the can body portion. The can body portion and the can bottom portion are connected by a connecting portion having a predetermined radius of curvature in the longitudinal section thereof, and an inclination angle formed between a tangent line connecting the grounding portion and the connecting portion in the can bottom section and a horizontal line is A can with an aluminum alloy small-capacity screw, which is 40 ° to 50 ° in a state where the can is upright.

  In Claim 1, the ratio V / d of the total internal volume V (ml) to the can body inner diameter d (mm) in a small-capacity threaded can is in the range of 2.0 to 3.6, and the internal volume The balance between the inner diameter of the can body and the height of the can was defined. Here, the total internal volume V is the internal volume (full capacity) when the contents are filled up to the open end of the screwed can. If V / d exceeds 3.6, the inner diameter of the can body becomes too thin with respect to the total internal volume, and there is a problem that the buckling strength of the can body decreases. Further, if V / d is less than 2.0, the inner diameter of the can body becomes too thick with respect to the total internal volume, so that the height of the can body portion is reduced, and the can body is opened when the consumer opens and closes the can body. It becomes difficult to hold the part by hand. By setting the value of V / d within the range of 2.0 to 3.6, the necessary buckling strength of the can body is secured, and the can body can be easily held and easily handled when opened and closed. It can be a body. Further, the ratio (D / d) of the outer diameter D (mm) of the mouth and neck with respect to the inner diameter d (mm) of the can body was defined to be in the range of 0.53 to 0.80. By setting D / d within this range, the total drawing amount from the can body diameter to the neck diameter at the time of forming the shoulder portion becomes small. Therefore, the number of drawing forming steps is increased to increase the number of drawing steps per step. By reducing the amount of drawing, it is possible to reduce the molding force applied to the can for each process. Therefore, in the present invention, even if the thickness t2 of the can barrel side wall is set to 0.17 mm or less, the can barrel does not buckle, the can body is reduced in weight, and the contact pressure type internal pressure inspection can be accurately performed. In addition, when D / d is less than 0.53, the total drawing amount from the can body diameter to the neck diameter becomes too large, so in the case of the same number of steps, the molding force per step becomes large, It becomes easy to produce buckling in a can body part. On the other hand, it is also conceivable to increase the number of processes to reduce the molding force per process. However, since the number of processes that can be molded by one molding machine is fixed and cannot be increased any further, it is necessary to increase the number of molding machines in order to reduce the molding force per process by increasing the number of processes. This increases the installation area, making it difficult to arrange and lay out the production equipment, increasing the equipment cost and increasing the production cost. Further, when the D / d exceeds 0.80, the total drawing amount is reduced, so that the increase in the wall thickness due to the reduced diameter is reduced, and the thick wall portion having the wall thickness necessary for good screw forming is obtained. This is not preferable because it cannot be formed on the mouth and neck. Furthermore, the height of the can body was defined to be in the range of 50 mm to 100 mm. By setting the height of the can body within this range, the can body can be easily held at the time of opening and closing. Moreover, the shape of the shoulder part was made into the dome shape which becomes a circular arc shape with a longitudinal section projecting outward. The dome shape is a shape that is not easily deformed even when an external force such as a molding load or a plugging load is applied in curl molding, so that even if the wall thickness of the shoulder portion is reduced, the depression of the shoulder portion can be prevented. . In addition, in order to reduce the weight of the can body by setting the thickness of the can bottom to an appropriate range with respect to the wall thickness of the can body, the thickness t1 of the center of the can bottom and the minimum wall thickness t2 of the can body (T1 / t2) was defined. By defining the ratio of the plate thickness t1 at the center of the bottom of the can and the wall thickness t2 of the thin portion of the side wall as 1.5 to 2.0, the strength is reduced and the weight is reduced by thinning the bottom of the can and the side wall. Thus, the weighted can can be obtained while maintaining the strength of the can body. That is, when t1 / t2 is smaller than 1.5, the strength of the bottom of the can is lowered because t1 becomes too thin, and buckling is likely to occur at the bottom of the can due to a molding load or a plugging load. On the other hand, when t1 / t2 is larger than 2.0, since the aluminum alloy plate having a thick original plate is used, t1 becomes too thick and the material cost increases. The problem of increasing costs arises.

  These effects are particularly high in a small-capacity screw can having a total internal volume of 190 ml or less. That is, as described above, in consideration of ease of gripping and ease of handling, a certain height of the can body is required. Although it depends on the shape of the can body, in order to make it easy to open and close the screwed can, the height of the can body part is at least about 50 mm in order to hold the can body part firmly by hand. is required. Therefore, the overall height of the can with a screw is generally required to be 100 mm or more. When the total content is 190 ml or less, the outer diameter of the can body is 300 ml. Compared to the above-mentioned large-capacity screwed can, it must be significantly smaller. When the wall thickness of the can body is the same, when the outer diameter of the can body decreases, the cross-sectional area of the can body wall in the cross section of the can body decreases accordingly. Therefore, even if the same load is applied to the can body, the smaller the outer diameter of the can body, the greater the stress and the more likely to buckle. That is, in a can with a small-capacity screw having a total inner volume of 190 ml or less in which the outer diameter of the can body must be reduced, the buckling strength is significantly reduced. Therefore, for such a small-capacity threaded can, by making the shape of the can body as defined in the present invention, a significant weight reduction of the can body can be achieved while preventing a decrease in strength. .

  In the present invention, a resin-coated aluminum alloy slope in which a resin is coated on one side or both sides of an aluminum alloy plate can be used. The resin used in the present invention is not particularly limited as long as it is usually used in the production of cans, and known thermoplastic resins and thermosetting resins such as polyester resins and polypropylene resins are used.

  When a resin layer is provided on the aluminum alloy plate, the metal plate and punch are formed on the inner surface of the can during drawing ironing or ironing even when the lubricant is not sufficiently applied to the surface of the resin-coated metal plate. Are not in direct contact with each other, and the aluminum alloy plate is scraped to generate metal powder, which eliminates the inconvenience of premature punch and die deterioration. In addition, when a resin layer is formed on the surface of the aluminum alloy plate that becomes the inner surface of the can. It is possible to reduce the coating amount in the step of applying the inner surface coating applied in the subsequent step, or to eliminate the step of applying the inner surface coating itself.

  When a thermoplastic resin is used as the resin for forming the resin layer on the aluminum alloy plate, a thermoplastic polyester resin is preferably used particularly from the viewpoint of heat resistance and content resistance. As a method of forming a thermoplastic resin layer on an aluminum alloy plate, a method of forming a resin layer by extruding molten resin onto the surface of an aluminum alloy plate, or forming a resin film in advance and then bonding the film to an adhesive or heat fusion A known method such as a method of forming a resin layer by sticking to an aluminum alloy plate can be appropriately used. When a resin film prepared in advance is bonded to an aluminum alloy plate with an adhesive, a polyester resin, an epoxy resin, or the like can be appropriately selected as the adhesive.

  When a thermosetting resin is used as the resin for forming the resin layer on the aluminum alloy plate, a thermosetting polyester resin is preferably used. As the thermosetting polyester resin, modified polyester resins such as epoxy-modified and urethane-modified can also be suitably used. As the curing agent to be added to the thermosetting resin, a known one can be used, but it is preferable to use an amino resin or a melamine resin because of excellent workability. In particular, when used as a food container, it is preferable to use a phenol resin for the inner surface. By using a phenol resin, elution of formalin into the contents can be prevented.

  According to a second aspect of the present invention, in the aluminum alloy small capacity screw can according to the first aspect, the height from the connecting portion between the shoulder and the mouth and neck to the open end of the mouth and neck is 20 to 26 mm. By setting the length shorter than the conventional one, the range of the thick portion formed in the vicinity of the mouth portion for forming the screw portion becomes narrow, so that the screwed can can be reduced in weight. In other words, in conventional cans with large-capacity screws, the height of the can is relatively high, so when filling the contents, the can body may become unstable and fall down. There was a need to do. At this time, the can body portion in a state where the contents are not filled is weak in strength, and if held, the can body portion may be damaged. Therefore, it was necessary to fill the region of the mouth / neck portion having a high wall thickness and a relatively high strength without a threaded portion connected to the shoulder portion. Here, the reason why the screw part is not held is that the screw part may be damaged by the holding. Therefore, conventionally, in the mouth and neck, it is necessary to set the height of the region where the screw portion is not formed to a height that can be held during filling, and the height of the entire mouth and neck may be 26 mm or less. I couldn't. However, a small-capacity threaded can has a lower can body height than a large-capacity threaded can, so the can body is relatively stable during filling. It is not necessary to hold the part, and the height of the mouth and neck can be 20 to 26 mm. In addition, when the height of the mouth-and-neck part is larger than 26 mm, the range of the thick part formed in the mouth-and-neck part for screw formation is increased, and the weight of the can body is increased, which is not preferable. Further, if the height of the mouth and neck is less than 20 mm, it is not preferable because the height necessary for forming the screw portion cannot be ensured and the screw cannot be formed.

  The invention of claim 3 is the aluminum alloy small capacity screw can according to claim 1 or 2, wherein the arc of the shoulder section and the neck of the mouth are connected via a bent portion having a predetermined radius of curvature. In addition, by defining the tangent angle α formed between the tangent line of the shoulder cross-section arc and the vertical line at the connection point between the shoulder portion and the bent portion as 30 ° to 60 °, the effect of further preventing the depression of the shoulder portion The shoulder structure with high strength can be obtained, and the weight of the threaded can can be further reduced.

  According to a fourth aspect of the present invention, in the aluminum alloy small capacity screw can according to any one of the first to third aspects, a grounding portion having a diameter smaller than a can body diameter at the bottom of the can, the grounding portion and the bottom of the can By forming a slanted part that connects aluminum, a can with a screw can be formed using an aluminum alloy plate with a thin original plate thickness and the plate thickness at the bottom of the can is made thinner than before. Bending and deformation are less likely to occur. That is, by adopting such a configuration, at the time of neck formation, it becomes possible to form the neck while holding the inclined portion by the can bottom holder that contacts the grounding portion and the inclined portion and holds the can bottom portion. It is possible to prevent the inclined portion due to the load, the buckling of the grounding portion, and the deformation of the central portion of the can bottom. In addition, by connecting the can body portion and the inclined portion via a connection portion having a predetermined radius of curvature, buckling in the vicinity of the connection portion between the can body portion and the inclined portion can be prevented.

  Further, in a state where the can body is in an upright state, the inclination angle β formed by the common tangent line connecting the connecting portion of the can body portion and the inclined portion and the grounding portion and the horizontal line is set to 40 ° to 50 °. The load applied to the bottom of the can is reduced with respect to the applied stoppering load, and deformation of the bottom of the can is prevented, so that further effective weight reduction is achieved. That is, since the can bottom cannot be held by the can bottom holding tool at the time of filling, it is not preferable because, when a stoppering load is applied, if the inclination angle becomes smaller than 40 °, the inclined portion tends to buckle. If it exceeds 50 °, the vertical load component applied to the bottom of the can increases when the can is subjected to a load. Is not preferable.

  When the inclination angle β exceeds 50 °, the length of the can barrel side wall is shortened, and the area of a region where printing can be performed on the can barrel side wall is reduced and the appearance characteristics are deteriorated. By setting the angle to 50 °, it is possible to secure the length of the side wall of the can body by suppressing the decrease in the area of the printing region, maintaining the strength of the bottom of the can without impairing the appearance as a container, It is possible to reduce the weight of the can.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a view showing a reduced weight small capacity screw can according to the present invention, and FIG. 2 is a view showing a manufacturing process of a light weight small capacity screw can according to the present invention. FIG. 3 is a view showing the bottom of a small-capacity screw can according to claim 4 of the present invention.

  The can 1 with a small capacity screw shown in FIG. 1 uses 3104-H19 material as an aluminum alloy material, and is formed from a material having a plate thickness of 0.28 mm by a manufacturing process as described later. 106 mm, the can body height h is about 64 mm, the total internal volume V is about 130 ml, the can body inner diameter d is 45 mm, and the ratio of the can volume to the can body inner diameter (V / d) is about 2.89. It is a small capacity screw can.

  The thickness t1 near the center of the bottom portion 2 is 0.28 mm, the minimum wall thickness t2 of the side wall of the can body 3 is 0.15 mm, and the value of t1 / t2 is 1.87. Further, in the can with a small capacity screw shown in FIG. 1, the outer diameter D of the mouth-and-neck portion 17 is 28 mm, and the ratio of the outer diameter D (mm) of the mouth-and-neck portion to the inner diameter d (mm) of the can body (D / d ) Is 0.62. The height H from the connection part of the shoulder part 16 and the mouth neck part 17 to the opening end of the mouth part is formed to 22 mm, and the can weight is 10.6 g. By reducing the diameter of the neck portion 17 from the can body diameter, a thick portion having an appropriate thickness necessary for forming the screw portion is formed, and the range in which the thick portion is formed is minimized. Therefore, the weight reduction of the threaded can is achieved without impairing the moldability of the screw part and the strength of the screw part. Further, in the can with a small capacity screw shown in FIG. 1, the shape of the shoulder portion 16 is formed so that the radius of curvature r1 of the arc of the cross section is 25 mm, and is in a dome shape that protrudes outward. . Thereby, even when the wall thickness of a shoulder part is made thin and a can with a screw is formed, the strength required for the shoulder part 16 can be maintained. This r1 is preferably in the range of 20 mm to 30 mm. When r1 is 20 mm or less, the tangent angle α may be 60 ° or more in relation to the outer diameter of the mouth and neck, and when r1 is 30 mm or more, the tangent angle α may be 30 ° or less. However, there is a problem that buckling is likely to occur. Further, the shoulder portion 16 and the mouth-and-neck portion 17 are connected via the bent portion 4 having a radius of curvature r2 of about 3 mm, and the tangent angle α between the tangent line and the vertical line at the connection point is about 45 °. Yes. The curvature radius r2 of the bent portion is preferably in the range of 1 to 5 mm. Outside this range, it may be difficult to make the tangent angle α in the range of 30 ° to 60 ° in relation to the outer diameter of the mouth and neck and the radius of curvature r1 of the shoulder, resulting in depression of the shoulder, etc. Since it becomes easy, it is not preferable. The small-capacity threaded can according to the present invention configured as described above is a conventional can in which a can having the same external dimensions is produced by using 3104 one H19 material having a plate thickness of 0.33 mm as an aluminum alloy material. Compared to the body, a weight reduction of about 0.7 g has been achieved.

  Next, a manufacturing process of the small capacity screw can according to the present invention will be described. In the present invention, the diameter D of the circular plate 10 obtained by punching an aluminum alloy plate into a circle is set to 2.5 times or more the inner diameter d of the can body, and the drawing is performed three times or more, so that a thinner aluminum alloy material is used than before. By doing so, a can with a small capacity | capacitance screw can be reduced in weight by thinning a can bottom part and reducing a ratio with the minimum thin part of a can body side wall part. That is, the wall thickness on the opening side of the cup 11 formed by drawing by using a circular plate 10 having a larger diameter than before and making the drawing three or more times to increase the total drawing ratio in the can body forming. Due to the effect of increasing the thickness, it is possible to suitably form a thick portion necessary for screw molding. When drawing molding is performed twice or less, if a can with a small-capacity screw having a can volume / can barrel inner diameter ratio (V / d) of more than 3.6 is manufactured, the drawing ratio in each drawing step Therefore, defects such as wrinkles and breakage of the can body occur and productivity is lowered, which is not preferable.

  FIG. 2 shows an example of a method for producing a small capacity screw can according to the present invention. First, an aluminum alloy plate is punched twice into a circular plate 10 having a diameter D obtained by punching an aluminum alloy plate into a circular shape that is 2.5 times the inner diameter d of the final product. Drawing and ironing, in which ironing is performed in the same process with a single punch stroke, is performed. In the present invention, the drawing may be performed in the same process as the ironing by a single punch stroke, or may be performed as a single drawing process.

  The can body 12 thus obtained is ironed to form a thin portion 15 in the can body, and a thick portion 14 for forming a screw is provided near the opening of the side wall portion 13. In the present embodiment, the maximum wall thickness t3 of the thick portion 14 is 0.24 mm, the minimum wall thickness t2 of the thin portion 15 is 0.15 mm, and the difference is 0.09 mm. If this difference exceeds 0.10 mm, the inner surface of the can body 12 is damaged when a punch (not shown) is pulled out from the can body 12 after ironing, so that the side wall portion can be made sufficiently thin. Can not. Therefore, in the present embodiment, the above difference is set to 0.10 mm or less.

  Next, after trimming a predetermined amount of the opening end side of the can body 12 obtained by ironing, the can body surface is subjected to processes such as chemical conversion treatment of the can body, printing of the outer surface, clear coating, inner surface coating, etc. Neck forming is performed to form the drawing multiple times. The opening end side of the can body is reduced in diameter by a predetermined amount by the neck forming process, and the mouth-and-neck portion 17 following the inclined shoulder portion 16 and the inclined shoulder portion 16 is formed. At this time, the wall thickness of the mouth-and-neck part increases, and a thick part necessary for screw molding can be formed. In order to obtain such an effect, the outer diameter D of the mouth and neck is preferably in the range of 28 mm to 33 mm. Thereafter, screw forming and curling are performed to form a threaded portion 18 on the outer periphery of the mouth and neck portion 17, a curled portion 19 at the open end of the mouth and neck portion 17, and the mouth and neck portion 17 following the inclined shoulder portion 16. By forming the bead 20 for engaging the lower end portion of the pilfer loop cap, a can with a small-capacity screw that is lighter than before can be obtained as a product. Note that the cap wound around the screw portion 18 may be made of metal or resin.

  FIG. 3 shows a longitudinal section of the bottom of the can in the threaded can according to the fourth aspect of the present invention. In this threaded can, a grounding portion 30 and an inclined portion 31 having a smaller diameter than the outer diameter of the can body are formed at the bottom of the can. The longitudinal section of the ground contact portion 30 is configured as a curved surface having a curvature radius r3 of 1 mm. The radius of curvature r3 of the ground contact portion 30 is preferably 0.5 to 2.0 mm. Outside this range, it is easy to cause buckling in the ground contact portion when receiving a large load from above. The connecting portion 33 between the inclined portion 31 and the can body portion 32 is connected by a curved surface portion having a longitudinal radius of curvature r4 of about 2.4 mm. The curvature radius r4 of the connecting portion 33 is preferably 2.0 mm or more. This is because in the range of less than 2.0 mm, buckling is likely to occur at the connection portion. And it forms so that the inclination | tilt angle (beta) which the tangent which connects the connection part 33 of this inclination part 31 and the can body part 32 and the earthing | grounding part 30 and a horizontal line may be set to about 45 degrees. This makes it possible to reduce buckling by reducing the load acting on the bottom of the can even if the thickness of the bottom of the can is reduced by using an aluminum alloy plate having a thin original thickness. Therefore, it is possible to make the container excellent in appearance.

  Hereinafter, in order to verify the effect of the present invention, examples and comparative examples will be described. In this example and comparative example, a JIS 3104-H19 material was used as the aluminum alloy plate, and a can with a small-capacity screw having the following dimensions was prepared by the above-described forming method.

  In all Examples and Comparative Examples, the outer diameter D of the neck and neck was 28 mm, the height H of the neck and neck was 22 mm, the tangent angle α was 45 °, and the curvature radius r2 of the bent portion was 3 mm. The bottom of the can has a shape including a grounding portion and an inclined portion, the radius of curvature r3 of the grounding portion is 1 mm, the radius of curvature r4 of the connecting portion between the can body and the bottom of the can is 2.4 mm, and the inclination angle β is 45 °. did. Other dimensions were as shown in Table 1.

  In addition, about the value of D / d, it is outside the numerical value range prescribed | regulated by this invention in Comparative Examples 1-3. Further, V / d is in Comparative Example 1 and Comparative Example 3, and t1 / t2 is in Comparative Example 1 and Comparative Example 2, which are outside the numerical ranges defined in the present invention.

  The cans with small capacities of the examples and comparative examples were each formed with 10 cans with the above dimensions, the weight and buckling strength of the cans were measured, and the average values were calculated for each of the examples and comparative examples. . Moreover, after filling each can body with 100 ml of water, filling a predetermined amount of liquid nitrogen, and winding a metal pilfer proof cap, an internal pressure test sample having an internal pressure of about 196 kPa was prepared. Ten cans were produced. And the internal pressure test | inspection of these cans was performed using the contact pressure type | formula internal pressure test | inspection apparatus of the structure described in patent document 3. FIG. After performing the pressure-type internal pressure test, the internal pressure was directly measured by breaking the can, and the measured values of the pressure-type internal pressure test were in the range of 5 kPa above and below the measured values by direct measurement for all samples. Goods were found to have good internal pressure test results, and even one can outside the range was considered bad. As a comprehensive evaluation, the object of the present invention can be achieved when the weight of the can body is 11.3 g or less, the buckling strength exceeds 1471N which is the minimum value required for the product, and the internal pressure inspection is good. As a result, the overall evaluation was evaluated as “good”, and the overall evaluation was evaluated as “poor” because otherwise the object of the present invention could not be achieved. The results are shown in Table 1.

  In Examples 1 to 3, since the can body satisfied the conditions of the present invention, the weight of the can body was light, the buckling strength was sufficient, and the results of the contact pressure test were also good. On the other hand, in Comparative Example 1, V / d is 1.90, which is lower than the lower limit value of 2.00, so that the inner diameter of the can body becomes too large with respect to the total inner volume, and the height of the can body portion is 28 mm. The can became difficult to hold when opening and closing. In addition, the weight of the can body is light, t2 is as thin as 0.164 mm, and the result of the contact pressure type internal pressure test is also good, but t1 / t2 is 1.40, which is below the lower limit of 1.50, The buckling strength with the bottom of the can was weak and the buckling strength was as low as 1401N. In Comparative Example 1, the value of D / d was less than the lower limit of 0.53, and the total drawing amount was large, so that a can that buckled in the can body occurred in the shoulder forming step. In Comparative Example 2, V / d was 2.41, which was within the numerical range defined by the present invention, but t2 was as thick as 0.190 mm, and the result of the contact pressure type internal pressure test was poor. Moreover, since the value of D / d was less than the lower limit of 0.53 and the total drawing amount was large, a can that buckled in the can body occurred in the shoulder forming step. In Comparative Example 3, the value of D / d exceeds the upper limit of 0.80, the total drawing amount is small, the amount of diameter reduction is small, and the thick wall portion necessary for screw forming is not formed. In the screw forming process, a can that caused buckling of the mouth and neck occurred. Further, t1 / t2 is 2.09, which exceeds the numerical range defined in the present invention, and since t1 is thick, the weight of the can is increased, and the weight reduction of the can cannot be achieved. Moreover, since V / d exceeded the upper limit of 3.76, 3.76, the buckling strength was as low as 1447N.

  In this example, 3104-H19 material was used as the aluminum alloy material, but other aluminum alloys such as 3004 material can be used as appropriate, and one or both sides of the plate material is coated with resin. A laminate material may be used.

It is a figure which shows the can with a small capacity | capacitance screw reduced in weight concerning this invention. It is a schematic diagram which shows the manufacturing process of the can with a small capacity | capacitance screw reduced in weight concerning this invention. It is a figure which shows the bottom part of the can with a small capacity | capacitance screw concerning Claim 4 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Can with a small capacity screw | thread, 2 ... Center part of can bottom, 3 ... Can trunk, 4 ... Bending part, 10 ... Circular plate, 11 ... Cup, 12 ... Can body, 13 ... Side wall part, 14 ... Thick part, DESCRIPTION OF SYMBOLS 15 ... Thin part, 16 ... Shoulder part, 17 ... Mouth and neck part, 18 ... Screw part, 19 ... Curl part, 20 ... Bead, 30 ... Grounding part, 31 ... Inclined part, 32 ... Can trunk part, 33 ... Connection part .

Claims (4)

Forming a bottomed cylindrical can in which the can bottom and can body are integrally formed by applying at least drawing and ironing to a circular plate obtained by punching an aluminum alloy plate or a resin-coated aluminum alloy plate into a substantially circular shape. The opening end side of the cylindrical can body portion of the bottomed cylindrical can that has been thinned is reduced in diameter to form an inclined shoulder portion and a small-diameter cylindrical mouth-and-neck portion. In a threaded can in which a thread part and a curl part are formed,
The ratio (D / d) of the outer diameter D (mm) of the mouth and neck to the inner diameter d (mm) of the can body is in the range of 0.53 to 0.80, and the shoulder has a longitudinal section protruding outward. The can body height h is in the range of 50 mm to 100 mm, and the ratio (V / d) of the total internal volume V (ml) to the can body inner diameter d (mm) is 2. 0 to 3.6, the ratio (t1 / t2) of the thickness t1 of the center of the bottom of the can to the minimum wall thickness t2 of the can body is in the range of 1.5 to 2.0, and t2 A can with a small capacity screw made of aluminum alloy, characterized in that is 0.17 mm or less.   The outer diameter of the mouth-and-neck part is 28 mm or more, and the mouth-and-neck part height from the connecting part of the shoulder part and the mouth-and-neck part to the opening end of the mouth-and-neck part is 20 to 26 mm. Item 2. An aluminum alloy can with a small capacity screw according to item 1.   The mouth and neck portion and the shoulder portion are connected by a bent portion having a predetermined radius of curvature in the cross section thereof, and contact the arc of the shoulder vertical section through a contact point between the shoulder portion and the bent portion. The small capacity made of aluminum alloy according to claim 1 or 2, wherein the tangent angle formed by the tangent and the vertical line has a shoulder shape of 30 ° to 60 ° in a state where the threaded can is upright. Screwed can.   The can bottom portion of the screwed can includes a grounding portion having a diameter smaller than the can body diameter, and an inclined portion that connects the grounding portion and the can body portion, and the can body portion and the can bottom portion have a predetermined curvature radius in a longitudinal section thereof. The inclination angle formed between the tangent line connecting the grounding portion and the connection portion in the cross section of the bottom of the can and the horizontal line is 40 ° to 50 ° with the can upright. The aluminum alloy small capacity screw can according to any one of claims 1 to 3.

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