GB2168313A - Pull can having aluminium can ends - Google Patents
Pull can having aluminium can ends Download PDFInfo
- Publication number
- GB2168313A GB2168313A GB08431688A GB8431688A GB2168313A GB 2168313 A GB2168313 A GB 2168313A GB 08431688 A GB08431688 A GB 08431688A GB 8431688 A GB8431688 A GB 8431688A GB 2168313 A GB2168313 A GB 2168313A
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- GB
- United Kingdom
- Prior art keywords
- score
- tearable
- equal
- area
- aluminium alloy
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
- B65D17/00—Rigid or semi-rigid containers specially constructed to be opened by cutting or piercing, or by tearing of frangible members or portions
- B65D17/28—Rigid or semi-rigid containers specially constructed to be opened by cutting or piercing, or by tearing of frangible members or portions at lines or points of weakness
- B65D17/401—Rigid or semi-rigid containers specially constructed to be opened by cutting or piercing, or by tearing of frangible members or portions at lines or points of weakness characterised by having the line of weakness provided in an end wall
- B65D17/4012—Rigid or semi-rigid containers specially constructed to be opened by cutting or piercing, or by tearing of frangible members or portions at lines or points of weakness characterised by having the line of weakness provided in an end wall for opening partially by means of a tearing tab
Abstract
A can body is made of a thin aluminium alloy sheet and has a can end (2) made from a thin aluminium alloy sheet having a yield strength in the range of from 24 to 29 kgf/mm<2> and an elongation equal to or greater than 6%, while the aperture ratio defined by the ratio of the removable area (4) within score (3) with respect to the total area of the can end is equal to or greater than 60% so that the pressure-resisting strength is at least 5 kgf/cm<2>. The tearable score (3) is spaced inwardly from the inner periphery of the bottom of the frustoconical seamed portion of the can end by a distance equal to or greater than 1mm, the inner radius of curvature of the corner fillet at the bottom of the frustoconical portion is equal to or less than 0.5 mm, and the taper angle of the frustoconical portion of the can end is equal to or less than 10 DEG . An auxiliary score having a residual thickness greater than that of the tearable score may be formed outwardly or inwardly of the tearable score. The residual thickness of the tearable score (3) may be increased from the thinnest portion adjacent to the point where the tab (8) is secured and a plurality of elongate ridges or grooves may be formed within the removable area (4) substantially perpendicular to the line passing through the tab and the centre of the can end in order to avoid sudden tearing of the tearable score and sufficient spilling of the contents. <IMAGE>
Description
SPECIFICATION
Pull cans having aluminium can ends
The present invention relates to cans having aluminium alloy can ends which can end is formed with a tearable score defining a removable area which can be torn from the can end so as to provide an opening for removal of the content of the can.
In an aluminium alloy can for containing beer therein which is being commonly sold at present, the body of the can having a bottom integrally formed therewith has a shape similar to that of a conventional aluminium alloy can for containing juice therein and the body is made of an aluminium alloy sheet of Japanese Industrial Standards (referred to as JIS hereinafter) A-3004 P-H-19 having a thickness of about 0.35 mm and formed by a deep drawing and ironing process, while the can end of the can which is sealingly curled with its peripheral portion together with the peripheral upper open end of the body to form a chine is made of an aluminium alloy sheet of JIS A-5052 P-H-38 having a thickness of about 0.30 mm (in case of a can having the internal volume of 350 ml), for example.A teardrop-shaped tearable score is formed in the can end by a pressing process, and a manipulating or pull tab having a gripping hole formed therein is secured to the removable area defined by the score and of a relatively small aperture ratio, by means of a rivet located at a position near the tip of the teardrop shape of the removable area, whereby the removable area can be torn from the can end by pulling the tab so that the rivet first breaks off the tip portion of the teardrop-shape of the removable area at which the rivet is secured, along the score, thereby providing an opening for removal of the content of the can.
In general, beer is said to taste most delicious when one gulps down the beer or takes a long noisy drink of the beer when it has been cooled to a temperature of about 5 to 10"C.
The discharge rate of beer out of a prior art can through the opening formed in the can end is low, so that the good taste of the beer cannot be obtained by using the prior art can presently produced and sold. This tendency is enhanced as the volume of the can decreases, even though the relationship between the aperature ratio and the volume of the can containing the beer is taken into consideration.
In order to solve the above problem, efforts have been made to increase the aperture ratio of a can.
However, since beer contains carbon dioxide gas so that the internal pressure of a can containing therein beer will sometimes rise to about Skgf/cm2 (5 bar) or more in the summer season, for example, when the can directly receives the sunlight construction of a can end has not ever been developed which can satisfy the requirements, so as to resist sufficiently such a high internal pressure and yet to be easily opened while it has a large aperature ratio for achieving good taste of beer, and can be produced at a lower cost.
It is an object of the present invention to provide a novel and useful construction of an aluminium alloy can end of an aluminium alloy can for containing therein pressurized liquid or carbonated beverage, such as beer which can end avoids the above described disadvantages of the prior art can end.
Another object is to provide an aluminium alloy can end of an alumimium alloy can adapted to sealingly contain pressurized liquid or carbonated beverage such as beer, which can resist sufficiently a high internal pressure which can end is formed with a score for severing the area defined thereby from the can end so as to provide an opening of sufficiently large area for removal of the content from the can to afford a superior taste of the content, such as beer, while it can be manufactured at a lower cost.
in order to enhance the pressure-resisting strength of the can end and to render the removal of the area defined by the tearable score for providing the opening easier while a great aperture ratio is achieved, in accordance with the invention, the aperture ratio is equal to or greater than 60% and the pressure-resisting strength is at least 5 kgf/cm2 (4.9 bar), an aluminium alloy having a yield strength in the range of 24 to 29 kgf/mm2 (2360 to 2840 bar) and the elongation equal to or greater than 6% (JIS A 5052 H-38, for example) is used for making the can end and the following two conditions: that the distance between the score and the internal corner formed along the sealingly curled peripheral portion of the can end is made equal to or greater than 1 mm and that the inner fillet radius of curvature of the internal corner formed along the sealingly curled peripheral portion of the can end is equal to or less than 0.5 mm; are adopted as the indispensable requirements for constructing the can end of the present invention.
One or any combination of the following three conditions may be adopted for advantageously constructing the can end of the present invention, as the diameter of the can is increased: these three conditions being that the taper angle of the sealingly curled peripheral portion of the can end in the frustoconical shape is equal or less 10 degrees, that an auxiliary score or groove having a residual thickness greater than that of the tearable or main score is provided between the tearable score and the internal corner formed along the inner periphery of the frustoconical sealingly curled portion of the can end in order to afford an appropriate deformation of the can end for assisting the tearing action of the removable area along the tearable score, and that an auxiliary score or groove having a residual thickness greater than that of the tearable score is formed in the removable area inwardly of the tearable score in order to afford an appropriate deformation of the can end for assisting the tearing action of the removable area along the tearable score. Further, a plurality of parallel elongated ridges or recessed grooves is preferably provided in the removable area in a direction perpendicular to the direction of tearing the re movable area to enable the removable area to be bent easily around the ridges or the grooves, thereby preventing rapid or sudden removal of the removable area, tending to cause spilling of the content out of the can as the aperture ratio increases.
The present invention is equally applicable to cans both of the so-called flat-type can end and the countersink-type can end, and particularly to cans of the small countersink-type can end proposed in accordance with the present invention.
The above objects are, therefore, achieved in accordance with the characteristic feature of the present invention by the provision of an aluminium alloy can end of an aluminium alloy can consisting of a cylindrical body having a closed bottom and an upper open end and made of a thin aluminium alloy sheet and a can end made of a thin aluminium alloy sheet with the peripheral edge thereof being sealingly curled together with the peripheral of the upper open end of the body of the can so as to form an upwardly diverging frustoconical portion along the periphery of the can end, thereby forming a hermetically sealed vessel adapted to sealingly contain therein pressurized liquid, such as carbonated beverage or beer, the can end being formed with a circular tearable score within the area of the surface of the can end along the periphery thereof so as to form a removable portion, a manipulating tab being secured at its proximal end or an appropriate position thereof to the can end within the removable area and adjacent to the tearable score so as to permit the removable area to be torn from the can end by pulling the manipulating tab, the can end being characterized in that it is formed of an aluminium alloy sheet which is so chosen or treated that it has a yield strength in the range of 24 to 29 kgf/mm2 (2360 to 2940 bar) and an elongation equal to or greater than 6%, while the aperture ratio, as defined by the ratio of the area defined by the score with respect to the total area of the can end is equal to or greater than 60%, so that the pressure-resisting strength of the can end is at least 5 kgf/cm2 (4.9 bar), the score being located at a position spaced from the inner periphery of the bottom of the frustoconical portion of the can end by a distance equal to or greater than 1 mm inwardly of the chine of the can end, while the inner radius of the curvature of the filleted corner formed at the periphery of the bottom of the frustoconical portion is equal to or less than 0.5 mm and up to the minimum value capable of being achieved, the pressureresisting strength of the can constructed as described above being found to be remarkably increased in comparison with the prior art cans as the residual thickness of the tearable score increases.
In accordance with a further feature of the present invention, the taper angle of the frustoconical portion formed by the peripheral portion of the can end is equal to or less than 10 .
In accordance with a still further feature of the present invention, an auxiliary score or groove may be formed between the main score, i.e. the tearable score, and the periphery of the bottom of the frustoconical portion of the can end, the residual thickness of the auxiliary groove or score being greater than that of the main or tearable score for enabling the can end to deform in order to assist the tearing operation by the main score.
Alternatively, at least an auxiliary score or groove having a residual thickness greater than that of the main score may be formed within the removable area defined by the main score. In this case, the distance between the auxiliary score and the main score at the nearest position therebetween is in the range of 3.2 to 15 mm in order to obtain most advantageous condition for enhancing the pressure-resisting strength of the can end.
In place of the auxiliary score, an annular groove may be formed on the outer or inner surface of the can end in order to achieve similar results, the residual thickness at the groove being smaller than that of the main or tearable score.
In accordance with a further feature of the present invention, the residual thickness of the main or tearable score may be made the thinnest at the position adjacent to the portion to which the tab is secured, the amount of the residual thickness increased gradually or stepwise in both peripheral directions along the score towards the position most remote from the above described adjacent position, in order to prevent the rapid or sudden tearing of the removable area defined by the main score, from the can end, so as to avoid spilling of the content when the can end is being opened.
In accordance with a still further feature of the present invention, a plurality of elongated parallel ridges or recessed grooves may be formed in the removable area of the can end, preferably at about the centre of the can end, and the ridges or the grooves are oriented in the direction substantially perpendicular to the line passing through the sharpened tip of the tab and the gripping hole thereof or the centre of the can end so that the removable area can be bent easily about the ridges or grooves, so that the gradual tearing of the removable area is ensured, so as to avoid the spilling of the content out of the can which might occur were no such ridges or grooves provided.
The can end described above may have a flat surface over the entire area defined by the peripheral corner of the frustoconical portion of the can end, or the can end may be formed with a relatively large counter-sunk portion along the peripheral of the frustoconical portion of the can end recessed inwardly from the flat surface of the removable area defined by the tearable score.
Alternatively, a small annular counter-sunk portion is preferably formed along the peripheral corner of the frustoconical portion which is recessed inwardly of the can body from the flat surface of the removable area defined by the tearable score in order to enhance more effectively the pressure-resisting strength of the can end.
In this case, the inner radius of the counter-sunk portion in cross-section may be equal to or less than 0.6 mm and the depth thereof recessed inwardly of the can body from the flat surface of the removable area defined by the tearable score is equal to or less than 2 mm, while the height of the frustoconical portion of the can body is equal to or less than 10 mm and the angle of divergence of the frustoconical portion with respect to the vertical line may be equal to or less than 15O.
The invention is further described, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a side elevational view with a half portion in cross-section showing a prior art aluminium alloy can;
Figure 2 is a plan view of the can of Figure 1;
Figure 3 is a perspective view showing an aluminium alloy can incorporating a can end made in accordance with the present invention.
Figure 4 is a fragmentary enlarged cross-sectional view as seen in the direction IV-IV indicated in Figure 3.
Figure 5 is a fragmentary enlarged cross-sectional view showing the distance between the score and the corner formed around the bottom of the frustoconical or chine portion of the can end to be set in accordance with the present invention.
Figure 6 is a fragmentary cross-sectional view similar to Figure 5 but showing the deformed state of the can end when an increased internal pressure is applied thereto;
Figure 7 is a fragmentary enlarged cross-sectional view showing the inner radius of curvature formed at the inner corner of the periphery of the bottom of the frustoconical or chine portion of the can end of the present invention;
Figure 8 is a graph showing the relationship between the severing force of the severable area defined by the score as well as the pressure-resisting strength of the can end and the residual thickness of the tearable score when the distance between the score and the corner around the bottom of the frustoconical portion of the can end is chosen in accordance with the present invention;;
Figure 9 is a graph showing the relationship between the tearing force of the removable area defined by the score as well as the pressure-resisting strength of the can end and the residual score thickness when the inner radius of curvature of the filleted corner around the bottom of the frustoconical portion of the can end is chosen in accordance with the present invention.
Figure 10 is a fragmentary enlarged cross-sectional view showing the taper angle of the peripheral frustoconical portion or chine of the can end of the present invention;
Figure 11 is a graph showing the relationship between the tearing force of the removable area defined by the score as well as the pressure-resisting strength of the can end and the amount of the residual score thickness when the taper angle is chosen in accordance with the present invention;
Figure 12 is a fragmentary cross-sectional view showing the construction of a small countersink type can end;;
Figure 13 is a graph showing a relationship between the tearing force of the portion within the score as well as the pressure-resisting strength of the can end and the residual score thickness wherein the curve of the solid line indicates the data obtained by a can end having a small countersink whereas the broken line curve shows the data obtained by a flat can end;
Figure 14 is a fragmentary enlarged cross-sectional view showing the provision of an auxiliary score or groove between the tearable score and the corner around the bottom of the frustoconical portion of the can end;
Figure 15 is a cross-sectional view similar to Figure 14 but showing the state of the can end when the can is subjected to an increased internal pressure;;
Figure 16 is a cross-sectional view similar to Figure 14 but showing an annular groove having a semicircular cross-section provided in place of the auxiliary score shown in Figure 14;
Figure 17 is a cross-sectional view similar to Figure 16 but showing a modified embodiment of the auxiliary groove located in the inside surface of the can end;
Figure 18 is a cross-sectional view showing the can end wherein an auxiliary score is formed within the removable area defined by the tearable score;
Figure 19 is a cross-sectional view similar to Figure 18 but showing a relatively large countersink type can end instead of the can end shown in Figure 18;
Figure 20 is a cross-sectional view similar to Figure 18 but showing a plurality of auxiliary scores provided within the removable area defined by the tearable score;;
Figure 21 is a plan view showing an auxiliary score in the form of a broken line instead of the form of the continuous line shown in Figure 18.
Figure 22 is a plan view similar to Figure 21 but showing an auxiliary score wherein a part of the auxiliary score is made in the form of a broken line;
Figure 23 is a plan view similar to Figure 21 but showing the auxiliary score or groove in the form of a continuous line located eccentrically with respect to the tearable score;
Figure 24 is a plan view showing the tearable score of the can end wherein the residual score thickness is thinnest at a point A and increases towards a point B in both directions along the score; and
Figure 25 is a fragmentary perspective view showing the manner in which the removable area to be torn from the can end is bent about ridges formed in the removable area.
Figures 1 and 2 show an example of a conventional aluminium alloy can for containing therein pressurised liquid, such as beer. The can comprises a body 1 having a closed bottom integrally formed therewith and made of an aluminium alloy sheet of JIS A-3004 P=H-19 having a thickness of 0.35mm, for example, and a can end 2 made of an alumimium alloy sheet of JIS A-5052 P=H-38 having a thickness of 0.31 mm with the peripheral portion being sealingly curled together with the upper peripheral open end of the body 1 so as to form a hermetically sealed vessel.The can end 2 is formed with a tearing score 3 and a manipulating or pull tab 8 having a gripping hole 6 is attached to a teardrop-shaped area 4 defined by the score 3 by a rivet 9 at the tip of the teardrop-shaped area 4 so that the area 4 can be removed from the can end 2 by pulling the tab 8 from the can end 2, the tearing being commenced at the portion adjacent to the rivet along the score 3 and continuing along the entire length of the score 3, thereby forming an opening for removal of the content of the can. As previously described, the conventional can end 2 has a relatively small tearable area 4 for forming the opening, and, therefore, good tasting beer cannot be obtained.
Preferred embodiments of the present invention will now be described in detail hereinafter with reference to Figures 3 to 25.
With reference to Figures 3 and 4, the aluminium alloy can in accordance with the present invention includes a body 1 having a closed bottom and an upper open end similar to that shown in Figure 1 and a can 2 with its peripheral portion being sealingly curled together with the peripheral portion of the upper open end of the body 1 so as to form an upwardly diverging frustoconical portion or chine along the periphery of the can end 2, thereby forming a hermetically sealed vessel for sealingly storing therein pressurized liquid, such as carbonated beverage or beer.
In order to permit the content in the can to be removed therefrom so that one can drink the content of the can, a circular tearing score 3 is formed in the can end 2 along the periphery thereof for enabling tearing away of the removable area 4 defined by the score 3 from the can end 2 so as to leave a remaining annular portion 5 in the can end 2, which forms the opening for removal of the content.A manipulating or pull tab 8 provided with a sharpened tip 7 at its prnximal end and a gripping hole 6 at its opposite end is attached to the removable area 4 at a position adjacent to the sharpened tip 7 or an appropriate position thereof by means of a rivet 9 secured thereto at a position adjacent to the score 3 within the area 4, the sharpened tip 7 being adapted to pierce a portion of the area 4 adjacent to the score 3, thereby permitting the removable area 4 to be torn from the can end 2, beginning at a position in the score 3 adjacent to the rivet 9, along the score 3 by gripping the gripping hole 6 with a finger of the operator and pulling the tab 8 apart from the can end 2 to provide an opening defined by the score 3, permitting the content in the can to be easily removed and drunk by a person in the manner affording the most delicious taste of the content of the can, such as beer.
Numerous tests have been made with the thickness t of the aluminium alloy sheet from which the can end 2 is made being 0.30 to 0.32 mm and the residual score thickness (score residual) C of the can end 2 (Figure 4) being 0.10 mm so as to find out under what conditions in the relationship between the yield strength (TO2 kgfimm2 (0.2% elongation) and the elongation 3% of the aluminium alloy sheet the highest pressure-resisting strength of the can end can be achieved.
The results of the tests were as follows:
Thickness t Yield Strength *02 Elongation 3 Results (mum) (kgf/mm2) (O/O) 0.32 31.4 9.8 non-effective
0.32 29.4 11.4
0.32 27.4 13.6 effective
0.32 29.4 8.2
0.30 26.1 8.1 effective
0.32 26.1 8.1 effective
wherein '-' indicates either effective or non-effective.
From the above, it can be seen that, in order to ensure the easy tearing action of the area 4 from the can end 2 for providing the opening having the aperture rate greater than 60% for enabling drinking of the content in the can with good taste, the aluminium alloy sheet from which the can end 2 is made must have the yield strength i2 in the range of 24 to 29 kgfxmm2 (2360 to 2840 bar) and the elongation 3 equal to or higher than 6%, the severing score 3 being spaced from the corner 10 formed along the periphery of the bottom of the frustoconical portion of the can end 2 by a distance / (as shown in Figures 5 and 6) equal to or greater than 1 mm, contrary to the prior art cans having the distance I smaller than 1 mm, while the inner radius of curvature R at the corner 10 of the bottom of the frustoconical portion of the can end 2 (as shown in Figure 7) is equal to or less than 0.5 mm.
As is noted, Figure 6 shows the state of the can end 2 of Figure 5 after an increased internal pressure is applied thereto. As is clearly shown in Figure 6, the positioning of the score 3 away from the corner 10 by a distance I equal to or greater than 1 mm seems to cause the configuration of the can end to as sume the form like the countersink-type, thereby increasing the pressure-resisting strength.
The above range of the yield strength o is selected so as to ensure the safety of the pressure-resisting strength having regard to variations in the mechanical properties of the aluminium alloy sheet from which the can end is formed.
As described above, the present invention provides an aluminium alloy can enabling an aperture ratio greater than 60% to be obtained for enhancing the good taste of the content, such as beer and permitting the area within the score to be easily torn away while it can withstand an internal pressure of at least 5 kgf/cm2 (4.9 bar) which might occur when the can directly receives the sunlight in the summer season and the can can be manufactured at a low cost.
Figure 8 shows the results of the comparison tests wherein can ends of the present invention made of an aluminium alloy of JIS A-5052, H-38 and having the numerical properties or the data: t = 0.32 mm, a,, = 29 kgf/mm2 (2840 bar), 8 = 6%, the taper angle a of the frustoconical portion of the can end = 13 , the inner fillet radius R of the bottom of the frustoconical portion = 0.5 mm, the diameter of the score = 44.5 mm, the inner diameter of the can end = 47.57 mm, the distance between the bottom periphery of the frustoconical portion and the score f = 1.0 mm, were compared with prior art cans made of the same alumimiun alloy and having the same numerical properties or the data of the can end as those of the present invention except that e is selected to be 0.8 mm. The ordinate in Figure 8 shows the score residual of the can end and the abscissa shows towards the left the severing or tearing force and towards the right the pressure-resisting strength, while the solid line shows the data of the cans having t = 1.0 mm of the present invention and the broken line shows the data of the prior art cans having e = 0.8 mm. As seen from Figure 8, the tearing forces of cans of the present invention and the prior art cans are substantially the same as each other, but the pressure-resisting strength of the cans of the present invention is greatly increased in comparison with that of the prior art cans.The pressure-resisting strength is found to be slightly lowered as the diameter of the can end increases.
Figure 9 shows the results of the comparison tests wherein the cans of the present invention having the can end made of an aluminium alloy of JIS A-5052, H-38 and having the numerical properties or the data: crO2 = 29 kgf/mm2, b = 6%, t = 0.32mm, f = 1 mm, ff = 13 the diameter of the score = 44.5 mm, the inner diameter of the can end = 47.5 mm, and R = 0.5 mm were compared with prior art cans having the same numerical properties or the data as those of the present invention except that the inner fillet radius F is 0.8 mm.The ordinate shows the residual score thickness or residual and the abscissa shows towards the left the severing or tearing force of the removable area and towards the right the pressureresisting strength of the can end, while the solid line shows the cans of the present invention having the fillet radius of curvature R equal to 0.5 mm and the broken line shows the prior art cans having the fillet radius of curvature Ro of 0.8 mm. As shown in Figure 9, the tearing force of can ends of the present invention is reduced in comparison with that of the prior art cans and the pressure-resisting strength of the cans of the present invention is remarkably increased in comparison with the prior art cans. It is also found that the pressure-resisting strength of the can ends of the present invention increase as the fillet radius of curvature R is reduced.The pressure-resisting strength is found to be slightly lowered as the diameter of the can end increases.
Further, in accordance with another feature of the present invention, the taper angle a of the frustoconical portion or chine of the inner peripheral portion of the can end is preferably equal to or less than 10 , e.g., a = 10 , as shown in Figure 10 in order to increase more effectively the pressure-resisting strength of the can end 2.
Numerous comparison tests of the cans of the present invention having the same numerical properties or the data as given in Figure 9 but having the taper angle a of 10 with the prior art cans made of the same aluminium alloy and having the same thickness of the can end and the taper angle v of substantially 13 have been made. The results are shown in Figure 11. In Figure 11 the ordinate indicates the score residual of the can end and the abscissa shows towards the left the severing or tearing force of the area defined by the score and the pressure-resisting strength towards the right, while the solid line curve shows the data of the cans of the present invention and the broken line curve shows the data of the prior art cans.As shown in Figure 11, the tearing force of both the can ends of the present invention and the prior art cans has the sarne value of about 3.6 kgf when the thickness of the can end is 0.32 mm and the score residual is 0.08 mm, for example, whereas the pressure-resisting strength of the cans of the present invention is about 6.4 kgf/cm2 which is about 1.5 kgf/cm2 greater than the pressure-resisting strength of the prior art cans of about 3 kgf/cm2.
As previously described, the present invention described hereinbefore equally applies to both the flat type can end having the flat surface over the entire area of the can end and the so-called countersink type can end having a relatively large annular countersink around the periphery of the can end recessed in the can body from the plane of the area defined by the score.
The pressure-resisting strength of the can end can be increased remarkably in comparison with the flat type can end, when a small countersink is formed around the periphery of the can end as described below in connection with Figure 12.
To this end, an annular countersink 5' is formed in the annular area 5 along the periphery of the bottom of the frustoconical portion 2' of the can end. The countersink 5' has an internal radius R in crosssection equal to or less than 0.5 mm, i.e., R < 0.5 mm, and it extends inwardly of the can body from the plane of the removable area 4 by a depth 5 equal to or less than 2 mm, while the height h of the frustoconical or chine portion is equal to or less than 10 mm. In this case, the taper angle a of the frustoconical portion 2' may be equal to or less than 10 .
The can end of the above configuration was compared with the flat type can end of the same material and thickness and the results showed that, when the score residual is equal to or greater than 0.1 mm, the pressure-resisting strength is remarkably increased, while the tearing force remains substantially unaltered.
Figure 13 shows the results of the comparison tests of the above described small countersink type can end having the same numerical properties or the data as those of Figure 9 with the flat type can end of the same numerical properties or the data as above.
Figure 14 shows a modified form of the can end 2 wherein an auxiliary score or groove 3' is arranged between the corner 10 and the main or tearing score 3. The auxiliary score 3' has a thicker score residual than the main score 3. The auxiliary score 3' enables the can end 2 to be easily deformed into the form of the countersink type when an increased internal pressure is applied thereto as shown in Figure 15, wherein the inner annular portion 5a is deformed in the upwardly convex form, while the outer annular portion 5b remains undeformed, thereby permitting the pressure-resisting strength to be increased.
Figure 16 shows a further modified form of the can end 2, wherein the auxiliary score 3' of Figure 14 is replaced by an annular groove 11 having a cross-section of substantially semi-circular form, the residual thickness at the groove 11 being greater than the score residual of the main score 3. The function of the groove 11 is the same as that of the auxiliary score 3'.
Figure 17 shows an alternative form of the can end 2 shown in Figure 16, wherein the annular grove 11' is formed in the inner surface of the can end 2. The function of the groove 11' is the same as that of the groove 11.
Figure 18 shows a further embodiment of the can end 2, wherein an auxiliary score or groove 3" is formed within the area defined by the tearing score 3 so as to permit the annular portion defined by the main score 3 and the auxiliary score 3" to be deformed and prevent a high stress from being concentrated locally of the tearing score 3 when an increased internal pressure is applied to the can end 2.
Figure 19 shows a modified form of the can end 2 wherein the auxiliary score 3" is formed in a can end 2' of the countersink type.
Figure 20 shows another embodiment in which a plurality of auxiliary scores 3" (two scores 3" in the illustrated embodiment) formed within the area defined by the tearing score 3.
Figure 21 shows the auxiliary score 3"a which is in the form of broken line instead of the score 3" in the form of a continuous line.
Figure 22 shows a modification of the score 3"b wherein a portion thereof is in the form of a broken line while the remaining portion is in the form of the continuous line.
Figure 23 shows a further modification of the auxiliary score 3" which is located eccentrically with respect to the tearing score 3. The distance between the tearing score 3 and the auxiliary score 3" at the minimum distance therebetween is selected to be in the range of 3.2 to 15 mm as follows:
Numerous pressure-resisting tests (pressure-resisting strength of 5.0 kgf/cm2) have been made to ascertain the optimum conditions for forming the auxiliary score or groove 3", 3"a and 3"b in order to increase most effectively the pressure-resisting strength of the can end, wherein the score residual at the severing score 2 was 0.11 mm, the score residual at the auxiliary score was 0.16 mm and the material of the can end had the yield strength a02 greater than 27.4 kgf/mm2.
The results are as follows:
Distance between 1 2 3 3.2 4 5 6 7 .. 15 16
the scores (mum) Results N N N - G G G G G N
where: N indicates non-effective
- indicates sometimes effective but sometimes non-effective
G indicates effective.
From the above, it can be seen that the distance between the tearing score 3 and the auxiliary score 3", 3"a or 3"b should be in the range of 3.2 mm and 15 mm.
It has been found out that the score residual of the can end is preferably made the thinnest at a point
A as shown in Figure 24 which is located adjacent to the rivet 9 which secures the tab 8 to the can end 2 as shown in Figure 3 so that the score residual is increased gradually in both directions along the score 3 towards the point B most remote from the point A.
The score residual at the point A is preferably 0.12 mm and that at the point B is preferably 0.17mm.
The variation in the amount of the score residual may be made stepwise as indicated in Figure 24, in which the range of 70 to 120 on both sides from the point A is 0.12 mm, for example, and the score residual at the remaining portion is 0.17 mm, for example. By varying the score residual as described above, when the area 4 is being torn from the can end by pulling the tab 8 the force to be applied to the tab 8 is gradually increased as the tearing proceeds from the point A towards the point B, due to the increase in the score residual so that rapid opening of the can end is prevented to avoid spilling of the content out of the can.
Finally, as shown in Figure 25, a plurality of elongated parallel ridges or recessed grooves 12 may be formed within the area 4 preferably in the region of the centre thereof, perpendicular to the line passing through the sharpened tip 7 and the gripping hole 6 of the tab 8 when it is placed in contact with the can end. By providing such ridges or grooves 12, the area 4 can be gradually torn, starting from the point adjacent to the sharpened tip 7 of the tab 8 so that the area 4 is gradually bent about the ridges or grooves 12 to assume easily the outwardly concave form when the tab 8 is pulled apart from the can, thereby avoiding rapid opening of the can end to prevent the content from being spilled.
If no ridges or grooves 12 are formed in the can end, since the can end tends to be held in the outwardly convex form in order to enhance the internal pressure-resisting strength, the area 4 might be torn away rapidly at once as a whole from the can end, thereby causing spilling of the content out of the can, because the area 4 tends to be kept in the flat form or in the outwardly convex form until it is completely torn from the can end.
Claims (8)
1. A can having a can end made of a thin aluminium alloy sheet with the peripheral edge of the can end being sealingly curled together with the periphery of said upper open end of the can body so as to form a chine thereby forming a hermetically sealed vessel adapted to sealingly contain therein pressurized liquid, said can end being formed with a frusto-conically diverging portion at said chine and with a substantially circular tearable score within the area of said can end and adjacent the periphery thereof so as to define a removable portion of said can end, a manipulating tab being secured at an appropriate portion thereof to said removable portion at a point adjacent said circular tearable score to permit the removable portion to be torn from said can end by pulling said manipulating tab, said aluminium alloy sheet forming said can end having a yield strength in the range of 24 to 29 kgf/mm2 (2360 to 2840 bar) and an elongation equal to or greater than 6%, while the aperture ratio defined by the ratio of the removable area with respect to the total area of said can end is equal to or greater than 60%, so that the pressure-resisting strength of said can end is at least 5 kgf/cm2 (4.9 bar), said score being spaced inwardly from the corner formed between the bottom of said frusto-conical portion and the can end area by a distance equal to or greater than imam, the radius of curvature of a fillet at said corner being equal to or less than 0.5 mm.
2. A can according to Claim 1, wherein the taper angle of said diverging frustoconical portion is equal to or less than 10 .
3. A can according to Claim 1 or 2, in which an auxiliary score or groove is formed between said tearable score and said corner, the residual thickness of said auxiliary score or groove being greater than that of said tearable score.
4. A can according to Claim 1 or 2, in which an auxiliary score or groove is formed within the removable portion of the can end area, the distance between said auxiliary score or groove and said tearable score at a minimum distance therebetween being in the range of 3.2 to 15mm, the residual thickness of said auxiliary score or groove being greater than that of said tearable score.
5. A can according to Claim 1 or 2, in which a plurality of parallel elongated ridges or recessed grooves is provided in said removable portion, said ridges or grooves being oriented substantially perpendicular to the line passing through said sharpened tip and said gripping hole of said tab or the centre of said can end.
6. A can according to any of Claims 1 to 5, wherein the residual thickness of said tearable score varies along the length thereof so that it is smallest at a point or region adjacent to the point at which said tab is secured and increases continuously or stepwise in both peripheral directions along said tearable score towards the point most remote from its smallest thickness point or region.
7. A can according to any preceding claim, in which the can body has a closed bottom end and is made from thin aluminium alloy sheet.
8. A can having a can end, constructed and adapted to be used substantially as herein described with reference to and as illustrated in Figures 3 to 25 of the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08431688A GB2168313A (en) | 1984-12-14 | 1984-12-14 | Pull can having aluminium can ends |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08431688A GB2168313A (en) | 1984-12-14 | 1984-12-14 | Pull can having aluminium can ends |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8431688D0 GB8431688D0 (en) | 1985-01-30 |
| GB2168313A true GB2168313A (en) | 1986-06-18 |
Family
ID=10571233
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08431688A Withdrawn GB2168313A (en) | 1984-12-14 | 1984-12-14 | Pull can having aluminium can ends |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2168313A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0673844A2 (en) * | 1994-03-03 | 1995-09-27 | Schmalbach-Lubeca AG | Beverage can with tear-lid for pourable products |
| WO1998046488A1 (en) * | 1997-04-16 | 1998-10-22 | Crown Cork & Seal Technologies Corporation | Can end |
| US6666933B2 (en) | 1997-04-16 | 2003-12-23 | Crown Cork & Seal Technologies Corporation | Can end, and method of manufacture therefor |
| WO2011026900A1 (en) * | 2009-09-04 | 2011-03-10 | Crown Packaging Technology, Inc. | Full aperture beverage can end |
| US9714114B2 (en) | 2013-11-08 | 2017-07-25 | Crown Packaging Technology, Inc. | Full aperture can end |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1422648A (en) * | 1972-02-28 | 1976-01-28 | Dorn Co V | Metal can |
| US4044915A (en) * | 1976-07-22 | 1977-08-30 | American Can Company | Container end closure |
| GB1549261A (en) * | 1975-06-30 | 1979-08-01 | Aluminum Co Of America | Container including an aluminium panel having a portion removable by tearing |
| US4258859A (en) * | 1979-02-02 | 1981-03-31 | Boise Cascade Corporation | No-fin scored metal ends for containers |
-
1984
- 1984-12-14 GB GB08431688A patent/GB2168313A/en not_active Withdrawn
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1422648A (en) * | 1972-02-28 | 1976-01-28 | Dorn Co V | Metal can |
| GB1549261A (en) * | 1975-06-30 | 1979-08-01 | Aluminum Co Of America | Container including an aluminium panel having a portion removable by tearing |
| US4044915A (en) * | 1976-07-22 | 1977-08-30 | American Can Company | Container end closure |
| US4258859A (en) * | 1979-02-02 | 1981-03-31 | Boise Cascade Corporation | No-fin scored metal ends for containers |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0673844A2 (en) * | 1994-03-03 | 1995-09-27 | Schmalbach-Lubeca AG | Beverage can with tear-lid for pourable products |
| EP0673844A3 (en) * | 1994-03-03 | 1995-12-20 | Schmalbach Lubeca | Beverage can with tear-lid for pourable products. |
| WO1998046488A1 (en) * | 1997-04-16 | 1998-10-22 | Crown Cork & Seal Technologies Corporation | Can end |
| US6666933B2 (en) | 1997-04-16 | 2003-12-23 | Crown Cork & Seal Technologies Corporation | Can end, and method of manufacture therefor |
| WO2011026900A1 (en) * | 2009-09-04 | 2011-03-10 | Crown Packaging Technology, Inc. | Full aperture beverage can end |
| US8939308B2 (en) | 2009-09-04 | 2015-01-27 | Crown Packaging Technology, Inc. | Full aperture beverage end |
| EP2878547A1 (en) * | 2009-09-04 | 2015-06-03 | Crown Packaging Technology, Inc | Full aperture beverage can end |
| US10053260B2 (en) | 2009-09-04 | 2018-08-21 | Crown Packaging Technology, Inc. | Full aperture beverage end |
| US9714114B2 (en) | 2013-11-08 | 2017-07-25 | Crown Packaging Technology, Inc. | Full aperture can end |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8431688D0 (en) | 1985-01-30 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |