Abstract:
A metal container with thread capable of preventing such a defect that the strength of a lower end of a mouth part and an upper end of a shoulder part of a container main body is non-resistant to a pressing force in radial and axial directions, and a part of the container may be collapsed or buckled during a capping operation where content is filled into the container and cap is fitted to the container automatically by a machine, characterized in that at least one or more inwardly curving smooth annular recessed parts ( 4 ) and at least one or more outwardly curving smooth annular projected parts ( 5 ) are formed in an area ranging from the lower end ( 2   a ) of the mouth part ( 2 ) of the container main body to around the upper end ( 3   a ) of a tapered shoulder part increasing gradually in radial direction.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to a metal container with thread in which a mouth part including a threaded part and an upper end of a shoulder part have an improved strength. The present invention further relates to a metal container with thread capable of maintaining a highly airtight condition.  
       BACKGROUND ART  
       [0002]     Conventionally, a metal container with thread, as shown in  FIG. 19 , is manufactured by drawing, drawing-and-ironing or impact forming from a metallic material such as aluminium. An open mouth part of such a metal container is closed airtight, as a cap is screwed on a threaded part formed in a periphery of the cylindrical mouth part.  FIG. 19  is a cross sectional view of a conventional metal container with thread. Denoted at  50  is a container main body, and the container main body  50  is formed by a curled part  51 , a mouth part  52  with a threaded part, a tapered shoulder part  53 , a trunk part  54  and a bottom part  55 , shown in this order from the top. A female screw of a cap  56  and a male screw of the mouth part  52  are fitted with each other, whereby the mouth part  52  of the container main body  50  is sealed up. The symbol  57  denotes packing. In such a container main body  50 , as shown in  FIG. 20 , the shoulder part  53  is formed to have a linear cross sectional shape up to its upper end  53   a,  and the upper end  53   a  of the shoulder part  53  is continuous up to a lower end  52   a  of the mouth part.  
         [0003]     Meanwhile, a metal container with thread as shown in  FIG. 21  is known and commercially available, where plurality of protruded parts  62  (three in  FIG. 21 ) are formed at schematic equal intervals entirely over a shoulder part  61  of a container main body  60 .  
         [0004]     However, as shown in  FIG. 20 , the container main body  50  shown in  FIG. 19  has a problem that the strength of the lower end  52   a  of the mouth part  52  and the upper end  53   a  (area W) of the shoulder part  53  is weak against pressure forces in a radial direction and an axial direction (pressing forces P, Q) therefore, the area W may be collapsed or buckled during a capping operation to fill content into the container and fit a cap to the container automatically using a machine.  
         [0005]     With respect to the container main body  60  shown in  FIG. 21 , a purpose of forming the plurality of protruded parts  62  entirely over the shoulder part  61  is to mainly achieve a design effect of the metal container with thread and to prevent the shoulder part  61  from getting wrinkled during a necking operation of manufacturing steps. Thus, an improvement in strength at the mouth part and the upper edge of the shoulder part is not intended here, accordingly no actual enhancement of strength is expected.  
         [0006]     On the other hand, as shown in  FIG. 22 , the curled part  51  is formed at the upper end of the mouth part  52  in the conventional metal container with thread to thereby ensure a better strength, safety for a user and sealable effect. In other words, by means of an axial clamping force developed as the female screw of the cap  56  is fitted to the male screw of the mouth part  52 , the packing  57  laid on an inner ceiling surface of the cap  56  abuts on a top surface of the curled part  51  formed at the upper end of the mouth part  52 , whereby an opening at the mouth part  52  is sealed up. A lower end  56   a  of the cap  56  is bent along a bead part (annular groove)  52   b  formed in the mouth part  52  and fitted with the upper area of the bead part to its end.  
         [0007]     However, since the packing  57  and the ceiling surface of the curled part  51  are in surface contact, such a closing structure has a problem with a sealing capability if the curled part  51  has a slight dimensional error and the surface contact is accordingly weak. In short, when content develops an internal pressure, the content may leak out between the packing  57  and the ceiling surface of the curled part  51 . Particularly, as for a metal container containing, a carbonated beverage such as beer and cola, it is required that the metal container is sealed up without fail again after opened once, do that the quality and the internal pressure of the remaining contained drink are maintained, so that an insufficient sealing capability becomes a problem.  
         [0008]     An attempt to improve a sealing capability by strongly tightening the cap  56  and increasing applied pressure between the packing  57  and the curled part  51  to one another invites the area W at the upper end of the shoulder part  53  shown in  FIG. 20  to twist more, and therefore, makes it easier for the area W to be buckled. If the tightening force is reduced to prevent such buckling, leakage tends to occur.  
         [0009]     On the other hand, in a conventional metal container, an area of the bead part  52   b  easily collapses when lower end  56   a  of the cap  56  is plastically deformed along the bead part  52   b  in the manner as shown in  FIG. 22 . Further, the cap  56  may be a screw cap with preformed thread or a roll-on type cap put on the mouth part  52  to be pressurized along the male screw of the mouth part to thereby form threads. In the latter case, a side wall of the cap  56  is pressed strongly in the radial direction toward inside, and therefore, the threaded part may easily collapse.  
         [0010]     In addition, where the metal container shown in  FIG. 19  uses a cap such as a Pilfer Proof cap (PP cap) and a similar Alten cap (also known as a flavor cap or a high-lock cap), to be fractured as opened in order to clearly indicate a user that the container has been unopened, the threaded part, the bead part and the like collapse more easily and the upper end of the shoulder part buckles more easily, since the strength of the cap is high.  
         [0011]     The present invention was made in view of the conventional problems described above, and accordingly, a first object of the present invention is to provide a metal container with the threaded part  52  and the lower end  52   a  of the mouth part as well as the upper end  53   a  (area W) of the shoulder part  53  having an improved strength in a radial direction and an axial direction. Further, a second object of the present invention is to provide a metal container with thread capable of maintaining a highly airtight condition.  
       DISCLOSURE OF THE INVENTION  
       [0012]     A metal container with thread according to the present invention is manufactured by drawing, drawing-and-ironing or impact forming from a metallic material with container main body consisting of a mouth part including a threaded part, a tapered shoulder part, a trunk part and a bottom part and maintaining a highly airtight condition with a cap screwed on, and is characterized in that at least one or more inwardly curving smooth annular recessed parts or at least one or more outwardly curving smooth annular protruded parts are formed around an upper end of said tapered shoulder part widening in a radial direction toward below from a lower end of said mouth part. According to a preferred embodiment, both said annular protruded parts and annular recessed parts are formed. Further, a bead part for bending a lower end of said cap for engagement may be formed in the vicinity of said lower end of said mouth part.  
         [0013]     A metal container with thread according to a second aspect of the present invention is manufactured by drawing, drawing-and-ironing or impact forming from a metallic material with container main body consisting of a mouth part including a threaded part, a tapered shoulder part, a trunk part and a bottom part and maintaining a highly airtight condition with a cap screwed on, and is characterized in that an annular slightly rounded projection is formed at an upper end of the mouth part so that when the cap is screwed on, the annular projection bites into packing laid on an inner surface of a ceiling surface of the cap and an air tight condition is realized.  
         [0014]     In such a metal container with thread, it is preferable that a curled part is formed at the upper end of the mouth part and a bent line is created along an upper end of the curled part of the upper end.  
         [0015]     The container main body may be formed by integral forming so that the mouth part including the threaded part, the tapered shoulder part, the trunk part and the bottom part are integral with each other, or alternatively, the mouth part including the threaded part and a tapered neck part may be formed integral with each other to thereby form an upper container body, the side wall part and the bottom part may be formed integral with each other to thereby form a lower container body, and the upper container body and the lower container body may be joined to each other. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a front cross sectional view showing a first preferred embodiment of the present invention;  
         [0017]      FIG. 2  is a cross sectional view showing a mouth part and an upper end of a shoulder part according to the first preferred embodiment of the present invention;  
         [0018]      FIG. 3  is an enlarged cross sectional view showing an area A according to the first preferred embodiment of the present invention;  
         [0019]      FIG. 4  is a cross sectional view showing a mouth part and an upper end of a shoulder part according to a second preferred embodiment of the present invention;  
         [0020]      FIG. 5  is a cross sectional view showing a mouth part and an upper end of a shoulder part according to a third preferred embodiment of the present invention;  
         [0021]      FIG. 6  is a cross sectional view showing a mouth part and an upper end of a shoulder part according to a fourth preferred embodiment of the present invention;  
         [0022]      FIG. 7  is an elevational view showing a crush strength test on a bead part of a metal container with thread according to the present invention;  
         [0023]      FIG. 8  is an elevational view showing a crush strength test on a threaded part of a metal container with thread according to the present invention;  
         [0024]      FIG. 9  is an elevational view showing a buckling strength test on a shoulder part of a metal container with thread according to the present invention;  
         [0025]      FIG. 10  is an elevational view showing a metal container with thread according to the present invention forming a mouth part, a shoulder part, a side wall part and a bottom part integrally with each other;  
         [0026]      FIG. 11  is an enlarged cross sectional view showing a mouth part having a threaded part of a metal container with thread according to a fifth preferred embodiment of the present invention;  
         [0027]      FIG. 12  is a cross sectional view showing a condition that a cap is screwed on the mouth part of the metal container with thread according to the fifth preferred embodiment of the present invention;  
         [0028]      FIG. 13  is a flow chart showing a method of attaching the cap to the mouth part of the metal container with thread according to the fifth preferred embodiment of the present invention;  
         [0029]      FIG. 14  is a cross sectional view showing a condition that a cap is screwed on a mouth part of a metal container with thread according to a sixth preferred embodiment of the present invention;  
         [0030]      FIG. 15  is a cross sectional view showing a condition that a cap is screwed on a mouth part of a metal container with thread according to a seventh preferred embodiment of the present invention;  
         [0031]      FIG. 16  is a cross sectional view showing a condition that a cap is screwed on a mouth part of a metal container with thread according to an eighth preferred embodiment of the present invention;  
         [0032]      FIG. 17  is a elevational view showing manufacturing of the metal container with thread according to the fifth preferred embodiment shown in  FIG. 10 ;  
         [0033]      FIG. 18  is a partial cross sectional elevational view showing a metal container with thread according to other embodiment of the present invention which is obtained by bonding an upper container body to a lower container body;  
         [0034]      FIG. 19  is a cross sectional view showing an example of a conventional metal container with thread;  
         [0035]      FIG. 20  is a cross sectional view showing a mouth part and an upper end of a shoulder part of the metal container with thread which is shown in  FIG. 19 ;  
         [0036]      FIG. 21  is a elevational view showing other example of a conventional metal container with thread;  
         [0037]      FIG. 22  is an enlarged cross sectional view showing a condition that a cap is screwed on a mouth part of a conventional metal container with thread. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0038]      FIGS. 1 through 3  show a metal container with thread according to a first preferred embodiment of the present invention. A container main body  1  of this container with thread is basically approximately the same as the conventional one, and as shown in  FIG. 1 , comprises a cylindrical mouth part  2 , a tapered shoulder part  3  downwardly contiguous from a lower end  2   a  of the mouth part  2 , a trunk part  11  contiguous from a lower end of the shoulder part, and a bottom part  12  closing a lower end of the trunk part  11 . As clearly shown in  FIG. 2 , a characteristic is that an inwardly curving smooth annular recessed part  4  is formed in an area around an upper end  3   a  of the shoulder part  3  (area A) and below this an outwardly curving smooth annular protruded part  5  is formed contiguously. A lower portion of the protruded part  5  is linearly continuous, like conventional ones. A portion in the vicinity of an upper end of the mouth part  2  has a slightly smaller diameter, and a curled part  13  curled up outwardly is formed at this upper end.  FIG. 3  is a cross sectional view further enlarging the area A according to the first preferred embodiment.  
         [0039]     The container main body  1  is obtained by drawing, drawing-and-ironing or impact forming a metallic material, such as aluminium for instance, into a cylindrical shape with bottom, thereafter forming the shoulder part and the mouth part by shoulder-drawing, a bead part  2   b  by rolling, then a threaded part, and further the curled part  13  at the upper end of the mouth part by curling part. In this embodiment, an upper portion of the container main body  1  including the mouth part  2  with the shoulder part  3  and a lower portion including the bottom part  12  are formed integral with each other.  
         [0040]     The diameter of the mouth part  2  is approximately 35 to 40 mm, for instance, preferably about 37.8 mm, while the diameter of the trunk part  11  is approximately 60 to 70 mm, preferably about 66.0 to 66.4 mm. The thickness of a material plate is approximately 0.2 to 0.3 mm, for example, preferably about 0.21 to 0.25 mm. The plate thickness of the mouth part  2  after forming is approximately 0.3 to 0.4 mm, preferably about 0.31 to 0.35 mm. The angle of the shoulder part  3  is approximately 25 to 30 degrees with respect to a perpendicular line. The plate thickness of the shoulder part  3  is around 0.30 to 0.34 mm in the vicinity of the upper end  3   a.  Meanwhile, the plate thickness of the trunk part  11  is about 0.11 to 0.15 mm, for instance. The plate thickness of the curled part  13  is approximately 0.33 to 0.37 mm.  
         [0041]     As shown in  FIG. 2 , a corrugated male screw  14  is formed by rolling and otherwise at the mouth part  2 . The thread diameter of the male screw  14  is about 36.9 to 37.5 mm. A skirt part  16  with somewhat larger diameter is formed in a lower part of the mouth part  2 , and the bead part  2   b  is formed below continuously. The bead part  2   b  is an annular groove and almost trapezoidal in cross section. The skirt part  16  and an upper wall  17   a  of the bead part  2   b  are, as described later, for caulking a lower end of a cap to be fractured to open, such as a Pilfer Proof cap and an Alten cap (See  FIG. 13 ).  
         [0042]     As shown in  FIG. 3 , a lower wall  17   b  of the bead part  2   b  is smoothly curved to be contiguous to the lower end  2   a  of the cylindrical mouth part, and the annular recessed part  4  is downwardly contiguous from the upper end  3   a  of the contiguous shoulder part to the lower end  2   a.  The recessed part  4 , in its cross section, preferably has a radius of curvature R of about 0.5 to 5 mm, and more preferably, approximately 2 to 4 mm. The angle of inclination (i.e., the degree of curve) θ of a common tangent line K of the recessed part  4  and the protruded part  5  is preferably about 35 to 60 degrees, and more preferably, approximately 40 to 50 degrees.  
         [0043]      FIG. 4  shows a metal container with thread according to a second preferred embodiment of the present invention. The container main body  1  of this metal container is characterized in that one inwardly curving smooth recessed part  6  is formed in a portion around the upper end  3   a  of the shoulder part (area B). The protruded part  5  of  FIG. 3  is not formed. The lower wall  17   b  of the bead part  2   b  is contiguous to the upper end of the shoulder part  3  while remaining inclined, and the recessed part  6  is formed somewhat below this. The recessed part  6  preferably has approximately the same radius of curvature, width and depth as the recessed part  4  according to the first preferred embodiment shown in  FIG. 3 .  
         [0044]      FIG. 5  shows a metal container with thread according to a third preferred embodiment of the present invention. The container main body  1  of this metal container is characterized in that one outwardly curving smooth protruded part  7  is formed in a portion around the upper end  3   a  of the shoulder part  3  (area C) continuous to the lower end  2   a  of the mouth part. No recessed part is formed. The protruded part  7  preferably has approximately the same cross sectional shape and angle of gradient (i.e., the degree of curve) as the protruded part  5  according to the first preferred embodiment.  
         [0045]      FIG. 6  shows a metal container with thread according to a fourth preferred embodiment of the present invention. The container main body  1  of this metal container is characterized in that an inwardly curving smooth recessed part  8  is formed in a portion around the upper end  3   a  of the shoulder part  3  (area D) continuing to the lower end  2   a  of the mouth part, and continuously an outwardly curving smooth protruded part  9  is formed, and further continuously an inwardly curving smooth recessed part  10  is formed. In other words, the two recessed parts  8  and  10  and one protruded part  9  are formed alternately in the area D. As another preferred embodiment, two recessed parts and two protruded parts may be formed alternately (not shown).  
         [0046]     Next, an effect of the metal containers with thread above is described. In the metal containers with thread according to the first to the fourth preferred embodiments, since the areas A, B, C and D are each bent to form the recessed parts and/or the protruded parts, the strength against pressing forces P and Q respectively in a radial direction and an axial direction improves. The radius of curvature R and the angle of inclination θ of the recessed parts and/or the protruded parts may be larger than the ranges described above. In the case that these values are larger, however, the strength against the pressing force P in the radial direction is stronger, while the strength against the pressing force Q in the axial direction is weaker. Hence, to improve in strength against both the pressing forces P and Q, the recessed parts described above preferably have the radius of curvature R of about 0.5 to 5 mm and the angle of θ of about 35 to 60 degrees.  
       Embodiment  
       [0047]     The following describes test results comparing the strength of the mouth part and the upper end of the shoulder part between the metal container with thread comprising the recessed part  4  and the protruded part  5  (Embodiment) according to the first preferred embodiment of the present invention and a conventional metal container with thread not comprising a recessed part or a protruded part (Comparison).  FIG. 7  shows a test for measuring a crush condition of the bead part  2   b  of the mouth part  2  when pressurized with a pressing force F 1  from above,  FIG. 8  shows a test for measuring a crush condition of the threaded part when pressurized the mouth part  2  from above with a pressing force F 2 , and  FIG. 9  shows a test for measuring a buckling strength when pressurized the upper end of the mouth  2  from above in the axial direction with a pressing force F 3 .  
         [0048]     [Test Condition] 
         [0049]     The outer diameter of the container: 66 mmø. The height of the container: 166 mm. The outer diameter of the mouth part: 37.8 mmø. The thickness of the threaded part and the bead part: 0.32 mm. The thickness of the lower end of the shoulder part: 0.2 mm. The thickness of the trunk of the container: 0.15 mm. The test results are as shown in Table 1.  
                                                   TABLE 1                           The number of testing n = 2                Crush                   Strength of   Crush Strength of   Buckling Strength of           Bead Part (N)   Threaded Part (N)   Shoulder Part (N)                        Comparison   113   137   1451       Embodiment   167   142   1657                  
 
         [0050]     From the test results above, it is found that with respect to the metal containers with thread according to the present invention, the crush strength of the bead part improves 47.8%, the crush strength of the threaded part improves 3.6% and the buckling strength of the shoulder part improves 14.2%.  
         [0051]     As described above, the present invention has an effect to improve the strength in an area around the mouth part of the metal container with thread, and particularly in an area from the lower end of the threaded part to the upper end of the shoulder part.  
         [0052]     Next, a second aspect of the present invention is described with reference to the associated drawings. FIGS.  10  to  12  show a fifth preferred embodiment of the present invention, and a cap  18  to cover the mouth part  2  is illustrated in an upper portion of the container main body  1  therein. The cap  18  has a cylindrical shape with bottom, and a female screw  19  to engage with the threaded part of the mouth part  2  is formed in a peripheral wall. The cap  18  is a so-called Pilfer Proof cap. Other caps to be broken as opened, such as an Alten cap, may be used instead.  
         [0053]     A characteristic of the fifth preferred embodiment is that an annular projection  13   a  is formed at the upper end of the mouth part  2  of the container main body  1  as shown in  FIGS. 11 and 12 . Other configurations are substantially the same as those shown in  FIG. 1 , and therefore, the same portions is denoted at the same reference symbols and is not described. In order to form the projection  13   a  at the outer upper end of the mouth part  2 , first, the curled part  13  in circular-shaped cross section is formed by a normal method, such as press work using a curling die, at the upper end of the mouth part  2 , a core  22  is inserted inside the container main body  1  as shown in  FIG. 17 , and then an outer circumferential surface of the curled part  13  is crushed with a roll  23  abutting on the curled part  13  from the outward side to thereby form a flat surface part  13   b  on the cylindrical surface approximately in parallel to the central axis of the container main body  1 . As a result, as shown in  FIG. 11 , the projection  13   a  is created at an intersection of an inner circumferential surface  13   c  and the flat surface part  13   b  of the curled part  13  as it originally has a circular shape in cross section, i.e., along a bent line outside the upper end. The projection  13   a  is loosely curved (over about 0.2 to 0.8 mm).  
         [0054]     In order to attach the cap  18  of the Pilfer Proof type to the container main body  1  manufactured in this manner, first, as denoted at a capping step S 1  shown in  FIG. 13 , the cap  18  is screwed on the mouth part  2  of the container main body  1 . In this condition, the upper end at the outer periphery of the cap  18  is cylindrical without any stepped area created. Meanwhile, the lower end remains directly downward. Further, in this condition, there is a gap between the flat surface part  13   b  of the curled part  13  and the inner circumferential surface of the cap  18 , and an outer circumferential part  24   a  of packing  24  fit inside a ceiling surface of the cap  18  expands sidewise. This however realizes a high sealable effect, since the projection  13   a  bites into the packing  24 .  
         [0055]     Following this, as denoted at a caulking step S 2  shown in  FIG. 13 , an upper end  18   a  at the outer periphery of the cap  18  is pressurized inwardly in the radial direction, to thereby form an annular stepped part. This makes the outer circumferential part  24   a  of packing  24  bent downward and held between the flat surface part  13   b  and an inner surface of the annular stepped part. This further enhances the sealable effect. Further, a lower end  18   b  of the cap is bent inwardly and pressed against the upper wall  17   a  of the bead part  2   b.  The cap  18  is consequently fit so as not to be removed unless broken.  
         [0056]     According to a sixth preferred embodiment shown in  FIG. 14 , a curled part  15  is applied crushing so as to be inclined at a certain angle with respect to the central axis of the container main body  1 , and a flat surface part  15   b  is accordingly created. At an intersection of the flat surface part  15   b  and the curled part  15 , approximately right above the curled part  15 , a projection  15   a  is formed. The projection  15   a  is loosely curved (with a radius of about 0.2 to 0.8 mm).  
         [0057]     According to a seventh preferred embodiment shown in  FIG. 15 , after forming a flat surface part  25   b  with a cylindrical surface at an outer periphery of the curled part  25  to be approximately parallel to the central axis of the container main body  1 , a flat surface part  25   c  inclined at a certain angle is further formed on the flat surface part  25   b.  Due to this, a projection  25   a  is created at an intersection of the flat surface part  25   c  and the curled part  25 , approximately right above the curled part  25 . The projection  25   a  is loosely curved (with a radius of about 0.2 to 0.8 mm). The inclined flat surface part  25   c  described above has a three-dimensional conical shape in reality.  
         [0058]     Further, according to an eighth preferred embodiment shown in  FIG. 16 , crushing applied to a curled part  35  is executed on the opposite side of the first preferred embodiment, namely, the inward side of the container main body  1 , so that a flat surface part  35   b  is formed on the inward side of the curled part  35 . Hence, a projection  35   a  is created at an inward upper end. The projection  35   a  is loosely curved (with a radius of about 0.2 to 0.8 mm).  
         [0059]     In any one of the preferred embodiments described above, the container main body  1  is formed as integrated one unit. However, the present invention is not limited to this. The container main body can be created by joining two or more components. The container main body  1  of the metal container with thread shown in  FIG. 18  is manufactured as separate units, an upper container body  1   a  comprising the mouth part  2  and the shoulder part  3  formed integral with each other and a lower container body  1   b  comprising the trunk part  11  and the bottom part  12  formed integral with each other. A cylindrical joint part  3   b  for capping an upper end of the trunk part  11  extends at the lower end of the shoulder part  3 . After forming the respective components, the joint part  3   b  is put on the upper end of the trunk part  11  and adhered with an adhesive or the like, whereby the container main body  1  is manufactured as one integrated unit. As for the upper container body  1   a,  typically, after forming the upper container body  1   a  into an upside-down cylindrical shape with bottom, the shoulder part  3  and the mouth part  2  are drawn, the upper end of the mouth part is then punched through to create an opening, and the bead part, the threaded part and the curled part  13  are thereafter formed in a manner similar to the above described. Hence, the mouth part  2  is relatively thick and has a high strength. Forming of the annular projection at the upper end of the curled part  13  and a method of the forming, etc. are the same as in the preferred embodiments described above.  
         [0060]     Next, an effect of the seal structure above is described. In the metal containers with thread described above, since the curled parts  13 ,  15 ,  25  and  35  are created and processed to form the respective flat surface parts  13   b,    15   b,    25   b,    25   c  and  35   b  as well as the projections  13   a,    15   a,    25   a  and  35   a  at the intersections of the curled parts and the flat surface parts, when the cap  18  is screwed on the threaded part of the mouth part  2  of the container main body  1 , the projections  13   a,    15   a,    25   a  and  35   a  bite and fit into the packing  24  laid inside the ceiling surface of the cap  18 . As a result, the opening of the mouth part  2  of the container main body  1  is sealed up without fail. In other words, at the positions where the projections  13   a,    15   a,    25   a  and  35   a  bite into the packing  24 , the projections  13   a,    15   a,    25   a,    35   a  reliably serve as annular seal points. As the cap  18  is screwed and clamps, the mouth part  2  of the container main body  1  is sealed up tightly. Hence, even if content is a beverage with an internal pressure, such as beer and cola, etc. it is possible to maintain the quality and the internal pressure of the leftover.  
         [0061]     As described above, the present invention has an effect to prevent leakage of content at the mouth part and maintain the quality and the internal pressure of a leftover beverage without fail. In addition, since a highly airtight condition is ensured, the cap need not be tightened too strong during a capping operation, so that it is possible to prevent the shoulder part and the like of the container main body from buckling and deformation.