JP2015205310A - can body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a can body excellent in design property and easy to grip, and achieving both of reduction of material cost of a trunk and high intensity.SOLUTION: In a can body 1, a predetermined position of a can trunk 2 is subjected to diameter expansion processing by expand-molding, a top cover 3 and a bottom cover 4 are tightened to vertical ends, and can height H is set to 80-110 mm. The can trunk 2 is configured so that, an upper largest diameter expansion part 13, a first taper wall part 18, a second taper wall part 19, and lower largest diameter expansion part 14 are formed by the diameter expansion processing, and an intermediate non-diameter expansion part 17 with not expanded diameter is provided on a boundary part between the first taper wall part 18 and second taper wall part 19. The can trunk 2 before subjected to the diameter expansion processing is formed so that outer diameter is in a range of 46.0-50.8 mm by a metallic plate whose thickness is 0.15-0.20 mm, and the upper largest diameter expansion part 13 and the lower largest diameter expansion part 14 are expanded so as to become outer diameter being 3-14%, with respect to the outer diameter of the can trunk 2 before subjected to diameter expansion processing.

Description

  The present invention relates to a can body including a can body subjected to a diameter expansion process by expanding molding.

  In can bodies, such as a drink can, what is provided with the can body which gave the diameter-expansion process by the expand molding is known (for example, refer patent document 1 and 2 below). This type of can body is a pressing surface provided on the outer surface of each split tool, in which a plurality of split tools inserted in a converged state inside the can body are moved radially outward within the can body. The surface is expanded to a predetermined outer diameter by pressing the surface outward.

  Expand molding can give the can body the desired unevenness depending on the shape of the pressing surface of the split tool, thereby giving the can body a high design or forming it into a shape that is easy to hold. Has been done.

Japanese Patent Publication No.54-6987 JP 2004-83095 A

  By the way, when obtaining a can body having high designability and ease of gripping by performing diameter expansion processing by expanding molding, the shape expanded by the diameter expansion processing becomes complicated. For this reason, there is a possibility that the thickness of the can body after the diameter expansion processing is stretched thin and the strength of the can body is lowered.

  Therefore, in the past, as the metal plate forming the can body, a relatively thick plate (specifically, a metal plate having a thickness of 0.22 mm as seen in Patent Document 2) is used. In this way, the strength reduction after the diameter expansion process is suppressed.

  However, if the plate thickness is increased as the metal plate forming the can body, the material cost of the can body increases, and an inexpensive can body cannot be provided. In this way, in a can body equipped with a can body subjected to diameter expansion processing by expanding molding, when considering design and ease of gripping, it is possible to achieve both reduction in material cost of the body portion and high strength. There was an inconvenience that became difficult.

  In view of the above points, an object of the present invention is to provide a can body that is excellent in design and easy to grip, and that achieves both a reduction in material cost of the body portion and high strength.

  The present invention comprises a cylindrical can body extending in the height direction, a canopy wound around the upper end of the can body, and a bottom lid wound around the lower end of the can body, In the can body having a can height of 80 mm to 110 mm, which is a dimension from the upper edge of the canopy to the lower edge of the bottom cover, the diameter of the can body is 80 mm to 110 mm. The upper maximum expanded portion expanded to the maximum outer diameter by the diameter expansion processing, the lower maximum expanded portion positioned at the lower portion and expanded to the maximum outer diameter by the diameter expansion processing, and the upper maximum expanded portion And an intermediate unexpanded portion that is not expanded and located between the lower maximum expanded portion and a shape that gradually increases in diameter from the intermediate unexpanded portion to the upper maximum expanded portion. The first taper wall portion by the diameter expansion process and the diameter gradually increases from the intermediate unexpanded portion to the lower maximum diameter expanded portion. A second taper wall portion formed by the diameter expansion process formed into a shape, and the can body before the diameter expansion process is formed by any metal plate having a plate thickness of 0.15 mm to 0.20 mm. The diameter is formed in any one of 46.0 mm to 50.8 mm, and the upper maximum diameter expansion portion and the lower maximum diameter expansion portion are 3% to the outer diameter of the can body before the diameter expansion processing It is characterized by being expanded to any outer diameter of 14%.

  The can body having a can height in the range of 80 mm to 110 mm is generally a size suitable for containing a beverage, and the outer diameter of the can body before diameter expansion processing is 46.0 mm to 50.8 mm. In general, existing can lid winding devices can be used.

  The can body of the present invention includes a can body that has been subjected to diameter expansion processing by expanding molding. That is, the upper maximum diameter expansion portion, the lower maximum diameter expansion portion, the intermediate non-diameter expansion portion, the first taper wall portion, and the second taper wall portion formed on the can body have an outer diameter of 46 before the diameter expansion processing. It is formed by subjecting any can body of 0 mm to 50.8 mm to diameter expansion processing.

  The outer diameter of the can body is the largest at the upper maximum diameter-expanded portion and the lower maximum diameter-expanded portion, and is the smallest at the intermediate unexpanded portion. And the 1st taper wall part is connected by the inclined surface from the upper largest diameter expansion part to the middle unexpanded part, and the 2nd taper wall part is an inclined surface from the lower largest diameter enlarged part to the middle unexpanded part. Are connected. By having the can body that is smoothly wrapped in this way, the can body is excellent in design and easy to grip.

  In the present invention, the upper maximum diameter expansion portion and the lower maximum diameter expansion portion of the can body are formed so as to have a diameter expansion amount of 3% to 14% with respect to the outer diameter of the can body before diameter expansion processing. Has been. By adopting such an amount of diameter expansion, excessive thinning of the can body diameter-enlarged portion accompanying diameter expansion processing is suppressed. And the thickness of the metal plate for forming the can body is 0 while maintaining sufficient strength, in combination with the can body structure in which the maximum diameter enlarged portion of the present invention is formed on a predetermined upper and lower portion of the can body. A thin metal plate of 15 mm to 0.20 mm can be used.

  As described above, the can body of the present invention uses any metal plate having a plate thickness of 0.15 mm to 0.20 mm, and the above configuration can suppress the thinning and maintain sufficient strength. Therefore, the material cost of the can body can be reduced, and an inexpensive can body can be provided.

  Further, in the present invention, an upper end non-expanded diameter portion that is not enlarged is provided between the upper maximum diameter enlarged portion and the canopy tightening portion, and an upper end from an upper edge of the canopy winding tightening portion is provided. The distance to the lower edge of the unexpanded portion is 4 mm to 9 mm, and the lower end unexpanded portion that has not been expanded is between the lower maximum diameter expanded portion and the bottom lid tightening portion. The distance from the lower edge of the tightening portion of the bottom lid to the upper edge of the lower diameter unexpanded portion is 4 mm to 9 mm.

  Since the canopy winding part and the bottom cover winding part are formed by folding by double winding of the can lid winding flange part and the can lid formed at the end of the can body, The strength is extremely high. On the other hand, the upper maximum diameter expanded portion and the lower maximum diameter expanded portion of the can body have the largest amount of diameter expansion processing, and may be thinner than the thickness of the can body before diameter expansion processing.

  In the present invention, the distance from the upper edge of the canopy tightening portion to the lower edge of the upper undiametered portion is set to 4 mm to 9 mm, and the lower edge of the bottom lid tightening portion to the upper edge of the lower undiametered portion. By setting the distance to 4 mm to 9 mm, the upper maximum diameter-expanded portion is located in the vicinity of the tightening portion of the canopy and the lower maximum diameter-expanding portion is located in the vicinity of the tightening portion of the bottom lid.

  According to this, since the upper maximum diameter expansion portion is reinforced by the tightening portion of the canopy and the lower maximum diameter expansion portion is reinforced by the tightening portion of the bottom lid, the strength is reduced by increasing the diameter of the thin can body. Can be suppressed sufficiently.

  Moreover, in this invention, it is preferable that the said can body is equipped with the cyclic | annular bead which gave the indentation process to the said intermediate | middle unexpanded diameter part along the circumferential direction of this can body. By providing the bead, the paneling strength (for example, deformation strength against the internal pressure change associated with the retort process) of the thin can barrel subjected to the diameter expansion process can be improved, and a higher strength can body can be provided. it can.

  Further, in the present invention, the can body is configured such that after the plurality of split tools are inserted into the can body in a converged state, each split tool is moved radially outward to press the split tool. The surface is expanded by pressing the inner peripheral surface of the can body, and extends in the height direction at a predetermined interval along the circumferential direction corresponding to the pressing surface of each split tool in the expanded molding. A plurality of diameter-expanded surfaces are formed, and the diameter-expanded surfaces include the upper largest diameter-expanded portion, the lower largest diameter-expanded portion, the intermediate undiametered portion, the first tapered wall portion, and the second tapered wall portion. It is characterized by forming.

  Further, in the split tool, the pressing surface is continuous with the upper pressing surface portion that forms the upper maximum diameter expanding portion, the lower pressing surface portion that forms the lower maximum diameter expanding portion, and the upper pressing surface portion. A first taper pressing surface portion forming a first taper wall portion; a second taper pressing surface portion forming the second taper wall portion continuously with the lower pressing surface portion; the first taper pressing surface portion and the second taper. A non-pressing portion that is positioned between the pressing surface portion and forms the intermediate unexpanded portion, and when the circumferential direction of the can body is defined as the width direction of the pressing surface, the upper pressing surface portion and the lower portion The pressing surface portion has a width smaller than the non-pressing portion and a shape extending in the vertical direction with the width dimension being constant, and the first taper pressing surface portion gradually has a width dimension from the upper pressing surface portion toward the non-pressing portion. The second shape is a large shape. The pad pressing surface portion has a shape in which the width dimension gradually increases from the lower pressing surface portion toward the non-pressing portion, and the expanded diameter surface of the can body is expanded by pressing the pressing surface. It is formed in the shape corresponding to the shape of this press surface at the time of a process.

  The upper maximum expanded portion, the lower maximum expanded portion, the intermediate unexpanded portion, the first tapered wall portion, and the second tapered wall portion of the can body are high at predetermined intervals along the circumferential direction of the can body. It is formed by a plurality of enlarged diameter surfaces extending in the vertical direction. The diameter-enlarging surface of the can body is formed by being pressed against the pressing surface of the split tool.

  The upper maximum expanded portion and the lower maximum expanded portion that are most expanded in the can body are formed by being pressed by the upper pressing surface portion and the lower pressing surface portion of the pressing surface of each split tool. The pressing force applied to the can body during the diameter expanding process gradually increases at the first taper pressing surface portion and the second taper pressing surface portion, and becomes maximum at the upper pressing surface portion and the lower pressing surface portion.

  At this time, since the upper pressing surface portion and the lower pressing surface portion of each split tool are the smallest surfaces among the pressing surfaces, the contact area with the inner surface of the can body is small. Since the upper maximum diameter expanded portion and the lower maximum diameter expanded portion of the can body are formed with a small contact area, it is advantageous that the diameter can be expanded with a relatively small pressing force with respect to the largest diameter expansion amount.

The side view which shows embodiment of the can of this invention. Explanatory drawing which shows each process of the diameter expansion process of a can body. It is a figure which shows the split-type tool and its operation | movement, (a) is the figure which looked at the half-section of the split-type tool of a convergence state, (b) is the figure which looked at the half-section of the split-type tool of a convergence state. Explanatory drawing which shows schematic structure and operation | movement of a recess molding apparatus. The side view which shows other embodiment of the can of this invention.

  Embodiments of the present invention will be described with reference to the drawings. The can body 1 of the present embodiment is generally called a three-piece can. As shown in FIG. 1, a cylindrical can body 2 and a canopy 3 wound around an upper end frenzy portion (not shown) of the can body 2. And a bottom lid 4 wound around a lower end flange portion (not shown) of the can body 2. A belt-like upper winding part 5 is formed at the upper end of the can body 2 by fastening the canopy 3, and a belt-like lower fastening part 6 is formed at the lower end of the can body 2 by fastening the bottom cover 4. Is formed.

  In such a can 1, for example, a canopy 3 is first wound around the upper end frenzy part of the can body 2, and a beverage such as coffee or tea is placed inside the can body 1 with the open side of the lower end of the can body 2 facing upward. Fill. Thereafter, the beverage is sealed inside the can body 1 by winding the bottom lid 4 around the lower end frenzy portion of the can body 2. And when drinking the drink inside the can 1, the drinking mouth is formed by breaking a break opening (not shown) provided in the canopy 3.

  The can body 1 has a can height H (a dimension from the upper edge of the canopy 3 to the lower edge of the bottom cover 4) of about 104 mm. The can height H is appropriately set in consideration of sales by a vending machine. In the configuration of the present invention, the can height H can be selected and set to any one of 80 mm to 110 mm.

  As shown in FIG. 1, the can body 2 has a plurality of diameter-enlarged surfaces that are formed by subjecting the diameter-enlargement process to the later-described expansion molding to extend in the height direction at predetermined intervals along the circumferential direction. 7 and a bead 8 formed by recessing the peripheral wall of the substantially central portion.

  Each enlarged-diameter surface 7 has a pair of rectangular surfaces 9 and 10 positioned at the upper end portion and the lower end portion, and a pair of heights that are vertically symmetrical via a bead 8 between the rectangular surfaces 9 and 10. The trapezoidal surfaces 11 and 12 are extremely long in the vertical direction.

  When the circumferential direction of the can body 2 is the width direction of the diameter-enlarged surface 7, the rectangular surfaces 9 and 10 have a shape extending in the vertical direction with a constant width dimension. Moreover, the width dimension of each rectangular surface 9 and 10 is smaller than the width dimension of the edge by the side of the bead 8 of the trapezoid surfaces 11 and 12. FIG. The trapezoidal surfaces 11 and 12 gradually increase in width from the rectangular surfaces 9 and 10 toward the bead 8 and incline toward the inside of the can body 2.

  Each rectangular surface 9 on the upper end side of the can body 1 has the largest protrusion amount toward the radially outer side of the can body 1. By arranging the rectangular surfaces 9 on the upper end side, the upper maximum diameter-expanded portion 13 having the largest diameter expansion processing amount is formed in the can body 2. Similarly, each rectangular surface 10 on the lower end side of the can body 1 has the largest amount of protrusion toward the radially outer side of the can body 1. And by arrange | positioning each rectangular surface 10 of a lower end side, the lower largest diameter expansion part 14 with the largest diameter expansion amount is formed in the can body 2 similarly to the upper largest diameter expansion part 13. Yes. The upper maximum diameter expanded portion 13 and the lower maximum diameter expanded portion 14 have an outer diameter of about 54 mm. Thereby, when the cans 1 come into contact with each other at the time of handling the cans 1 or when the cans 1 rotate and move in the vending machine, the outer peripheral surface of the can body 2 has the upper maximum diameter expanded portion 13 and the lower maximum portion. Since contact is made on the surface of the enlarged diameter portion 14 having the maximum diameter, damage to the can 1 is suppressed.

  A non-expanded upper end unexpanded portion 15 is provided between the upper maximum expanded portion 13 in the can body 2 and the upper tightening portion 5 of the canopy 3, and the lower maximum expanded portion in the can body 2. Between the portion 14 and the lower tightening portion 6 of the bottom lid 4, a lower end unexpanded portion 16 that is not expanded is provided. The upper end unexpanded portion 15 and the lower end unexpanded portion 16 have an outer diameter of about 50.8 mm, which is substantially equal to the outer diameter of the can body 2 before the diameter expanding process described later.

  As shown in FIG. 2A, the can body 2 before the diameter expansion process is formed in a cylinder having the same diameter (outer diameter is about 50.8 mm) from the upper end to the lower end. The can body 2 before the diameter expansion processing is formed by rounding a metal plate such as a rectangular tin-plated steel plate having a plate thickness of 0.17 mm into a cylindrical shape and welding the edges. Although not shown, the metal plate is provided with a protective coating layer made of a polyester film on the outer peripheral surface and the inner peripheral surface when the can body 2 is formed. Furthermore, printing such as product display is performed on the surface that becomes the outer peripheral surface when the can body 2 is formed.

  Conventionally, a can body subjected to diameter expansion processing by expansion molding has been formed by a metal plate having a wall thickness of 0.22 mm. Compared to this, a metal having a plate thickness of 0.17 mm as in this embodiment. The can body 2 using a plate is thin. In this way, by forming the can body 2 with a thin metal plate, the material cost of the can body 2 can be reduced, and an inexpensive can body 1 can be provided.

  Further, since a protective coating layer made of a polyester film is provided on the outer peripheral surface and the inner peripheral surface of the can body 2, the can body 2 can be used during diameter expansion processing and indentation processing, which will be described later, and at the time of sale. Damage such as scratches is prevented.

  Further, as shown in FIG. 1, the can 1 includes a distance L1 from the upper edge of the upper winding portion 5 of the canopy 3 to the lower edge of the upper undiametered portion 15 and the lower winding portion 6 of the bottom lid 4. The distance L2 from the lower edge to the upper edge of the lower end undiametered portion 16 is 5 mm. Accordingly, the upper maximum diameter expanded portion 13 is positioned in the vicinity of the upper winding tightening portion 5, and the lower maximum diameter expanding portion 14 is positioned in the vicinity of the lower winding tightening portion 6.

  Since the upper winding portion 5 and the lower winding portion 6 are formed by folding the peripheral portions of the lids 3 and 4 and the end portions of the can body 2, the strength against external force is extremely high. On the other hand, the upper maximum diameter expanded portion 13 and the lower maximum diameter expanded portion 14 are thinner than the thickness of the can body 2 before the diameter expansion processing because the amount of diameter expansion processing is the largest, as in this embodiment. In particular, when the can body 2 is thin, there is a concern that the strength may be lowered.

  However, in the can body 1 of the present embodiment, as will be described later, the upper largest diameter-expanded portion 13 and the lower largest diameter-expanded portion 14 have a diameter expansion amount of about 6.3% with respect to the outer diameter before diameter expansion. As a result, thinning due to diameter expansion processing is suppressed. Further, the upper maximum expanded portion 13 and the lower maximum expanded portion 14 are positioned in the vicinity of the upper winding portion 5 and the lower winding portion 6, respectively, so that the upper maximum expanded portion 13 is located at the upper portion. The lower maximum diameter enlarged portion 14 is reinforced by the lower tightening portion 6. Thus, in the can body 1 of this embodiment, the strength reduction by expanding the diameter of the thin can body 2 is sufficiently suppressed.

  According to the inventor's knowledge, the distances L1 and L2 are preferably set within a range of 4 mm to 9 mm. If the distances L1 and L2 are smaller than 4 mm, it is difficult to wind the lids 3 and 4 by a can lid winding device (not shown). If the distances L1 and L2 are larger than 9 mm, the upper maximum diameter expanded portion 13 and the lower maximum diameter expanded portion 14 cannot be sufficiently obtained by the upper winding portion 5 and the lower winding portion 6.

  The central portion of the can body 2 located between the upper maximum expanded portion 13 and the lower maximum expanded portion 14 becomes an intermediate unexpanded portion 17 that has not been expanded in diameter. A bead 8 is formed. The intermediate unexpanded portion 17 in the state where the bead 8 is not formed is approximately 50.8 mm which is substantially equal to the outer diameter of the can body 2 before the diameter expansion process described later. Therefore, the outer diameter of the can body 2 before the diameter expansion process is not maintained. The bead 8 has a depth of 0.3 mm and a height of 7 mm, and is continuously formed on the entire circumference of the can body 2.

  Each trapezoidal surface 11 on the upper half side of the can body 2 is disposed between the intermediate unexpanded portion 17 and the upper maximum expanded portion 13, and gradually increases in diameter toward the upper maximum expanded portion 13. A first taper wall portion 18 is formed. Similarly, each trapezoidal surface 12 on the lower half side of the can body 2 is disposed between the intermediate unexpanded portion 17 and the lower maximum expanded portion 14 toward the lower maximum expanded portion 14. A second tapered wall portion 19 having a gradually increasing diameter is formed.

  As described above, the can body 1 has an extremely high design by providing the can body 2 with the enlarged surface 7. Moreover, since the can body 1 has a shape constricted by the first taper wall portion 18 and the second taper wall portion 19 of the can body 2, it can be easily gripped, and the can body 1 can be prevented from sliding off from the hand. Further, the first tapered wall portion 18 and the second tapered wall portion 19 gradually decrease in diameter toward the intermediate unexpanded portion 17 of the can body 2, so that the thickness of the central portion of the can body 2 is increased. It becomes a relatively thick state. As a result, the can body 2 having an enlarged diameter can be obtained without causing a significant decrease in paneling strength (for example, deformation strength against changes in internal pressure associated with retort processing).

  The can body 2 of the can body 1 shown in FIG. 1 has a dimensional difference between the outer diameters of the upper maximum expanded portion 13 and the lower maximum expanded portion 14 and the outer diameters of the upper unexpanded portion 15 and the lower unexpanded portion 16. As can be seen from the above, the maximum outer diameter is expanded to about 6.3% with respect to the can body 2 before the diameter expansion process by the diameter expansion process by the expansion molding.

  As the can body 2 before the diameter expansion process, one having an outer diameter of 46.0 mm to 50.8 mm is selected and used. Thereby, the existing can lid winding device can be used, and the equipment change becomes unnecessary. And in the can body 2, it is necessary to set the diameter expansion amount after diameter expansion in the range of 3% to 14% with respect to the outer diameter before diameter expansion, and a more preferable diameter expansion amount is 3% to 7%. %. In the present embodiment, the upper maximum expanded portion 13 and the lower maximum expanded portion 14 are expanded by about 6.3% with respect to the outer diameter before the expansion.

  According to the inventor's knowledge, when the amount of expansion of the upper maximum expanded portion 13 and the lower maximum expanded portion 14 is less than 3%, the expanded surface 7 is hardly formed on the can body 2 and the design is high. You won't get easy grip. Moreover, if the amount of diameter expansion of the upper maximum diameter expansion part 13 and the lower maximum diameter expansion part 14 exceeds 14%, the upper maximum diameter expansion part 13 and the lower maximum diameter expansion part 14 are extremely thinned, resulting in a decrease in strength. Not only that, printing such as product display provided on the outer peripheral surface of the can body 2 is distorted and visibility is lowered.

  Further, by setting the amount of diameter expansion after expansion within the range of 3% to 14% with respect to the outer diameter before diameter expansion, the thickness of the metal plate forming the can body 2 is 0.15 mm to 0 mm. Any one of 20 mm can be used, and the can body 2 subjected to the diameter expansion process can be formed using a thin metal plate, so that the material cost can be reduced.

  Further, by providing the beads 8, the paneling strength of the thin can body 2 subjected to the diameter expansion process can be improved. The depth and width of the bead 8 are not limited to the above-described dimensions employed in the present embodiment. According to the knowledge of the inventors, the depth is set to 0.2 mm to 1.0 mm and the width is 2 mm to 10 mm. Is preferred. When the depth of the bead 8 is smaller than 0.2 mm, the paneling strength cannot be improved by the bead 8. When the depth is larger than 1.0 mm, the formation portion of the bead 8 becomes extremely thin and the paneling strength cannot be improved. . If the width of the bead 8 is less than 2 mm, it is difficult to indent, and if it is greater than 10 mm, the area overlapping with the expanded portion becomes large, so a burden is imposed on the processing of the can body 2, and the can body The strength of 2 is reduced. In addition, although not illustrated separately from the present embodiment, a plurality of beads 8 may be provided adjacent to each other in the height direction.

  Next, the formation of the enlarged diameter surface 7 by the diameter expansion process of the can body 2 and the formation of the bead 8 by the indentation process will be described. As shown in FIG. 2 (a), the can body 2 is subjected to a diameter expansion process by expansion molding on a cylindrical body having the same diameter from the upper end to the lower end. The can body 2 subjected to the diameter expansion process by the expansion molding has a shape shown in FIG. 2B, and the diameter expansion surface 7 is formed. Thereafter, the can body 2 having the enlarged diameter surface 7 is recessed. Thereby, as shown in FIG.2 (c), the bead 8 is formed.

  Thereafter, although not shown, a frenzy (upper end frenzy part and lower end frenzy part described above) is formed in each of the upper undiametered portion 15 and the lower undiametered portion 16 of the can body 2, and the canopy 3, The can 1 shown in FIG. 1 is obtained by double-clamping the bottom lid 4 using a winding device.

  The diameter expansion process is performed by an expanding apparatus 20 whose main part is shown in FIGS. 3 (a) and 3 (b). The expanding apparatus 20 includes twelve split tools 21 having the same shape and arranged circumferentially. Each split tool 21 has a length corresponding to the height dimension of the can body 2, and a pressing surface 22 that abuts against the inner peripheral surface of the can body 2 is formed on the outer surface thereof. Note that the number of the split tool 21 is not limited to 12, and can be changed according to the outer diameter of the can body 2 before the diameter expanding process. However, when the outer diameter of the can body 2 before the diameter expansion process is 46.0 mm to 50.8 mm, it is preferable that the range is 9 to 14 pieces.

  A columnar member 23 is provided inside each split tool 21. The columnar member 23 has a shape that gradually decreases in diameter toward the lower side, and a tapered surface 24 is formed on the outer periphery thereof. An inclined surface 25 corresponding to the tapered surface 24 of the columnar member 23 is formed inside each split tool 21.

  The split tool 21 is formed with a groove 26 at its upper end and lower end. Each groove 26 is provided with a ring-shaped spring member 27. As shown in FIG. 3A, the spring member 27 biases each split tool 21 in the direction of convergence.

  The columnar member 23 is moved up and down in the vertical direction by a lifting means (not shown). When the columnar member 23 moves downward, the tapered surface 24 moves along the inclined surface 25 of each split tool 21. Accordingly, each split tool 21 moves outward in the horizontal direction against the bias of the spring member 27.

  Thereby, each split-type tool 21 is moved radially outward, and the split-type tools 21 adjacent to each other are spread apart from each other in the circumferential direction as shown in FIG. On the contrary, when the columnar member 23 moves upward, the tapered surface 24 moves along the inclined surface 25 of each split tool 21, and is converged as shown in FIG. It becomes.

  The pressing surface 22 of the split tool 21 is curved in a shape along the circumferential direction of the can body 2, and includes an upper rising surface portion 22a, an upper pressing surface portion 22b, a first taper pressing surface portion 22c, a non-pressing portion 22d, and a second. It consists of seven surfaces: a taper pressing surface portion 22e, a lower pressing surface portion 22f, and a lower rising surface portion 22g.

  The upper pressing surface portion 22b and the lower pressing surface portion 22f are the smallest rectangular surfaces (surfaces extending in the vertical direction with a constant width dimension) among the pressing surfaces 22 and facing the expanding direction of each split tool 21. Is the most prominent. The upper pressing surface portion 22b and the lower pressing surface portion 22f form rectangular surfaces 9 and 10 (see FIG. 1) on the can body 2.

  The first taper pressing surface portion 22c and the second taper pressing surface portion 22e are surfaces having a shape in which the width dimension gradually increases toward the non-pressing portion 22d, and the direction becomes deeper toward the non-pressing portion 22d (columnar shape). It is inclined in a direction approaching the member 23). The first taper pressing surface portion 22c and the second taper pressing surface portion 22e form trapezoidal surfaces 11 and 12 (see FIG. 1) on the can body 2.

  The non-pressing portion 22d is a linear corner portion that is the longest in the circumferential direction in the pressing surface 22, and is located at the boundary between the first taper pressing surface portion 22c and the second taper pressing surface portion 22e. The non-pressing portion 22d forms an intermediate unexpanded portion 17 (see FIG. 2B) in the can body 2.

  When subjecting the can body 2 to diameter expansion using the expand forming apparatus 20, first, each split mold tool 21 in a converged state is inserted into the unprocessed can body 2 as shown in FIG. To do. Next, as shown in FIG. 3B, the columnar member 23 is moved downward, and each split tool 21 is moved radially. Thereby, each split type tool 21 spreads the can body 2 from the inside, and the can body 2 is diameter-expanded.

  The pressing force of each split mold tool 21 against the can body 2 is set in consideration of the spring back of the can body 2 when the pressing force is released. Further, the non-pressing portion 22d does not press the inner surface of the can body 2 at the time of expansion of each split tool 21, but is designed to return to an outer diameter at which the can body 2 is not pressed when the pressing is released. Therefore, in the present invention, substantially no pressing (non-pressing) is assumed.

  Then, the enlarged diameter surface 7 having a shape corresponding to the pressing surface 22 of each split tool 21 is formed on the can body 2 pressed from the inside by the pressing surface 22 of each split tool 21. That is, the can body 2 has a rectangular surface 9 (upper maximum diameter expanded portion 13), a trapezoid surface 11 (first taper wall portion 18), and a trapezoid surface 12 (second taper wall portion 19) constituting the diameter expansion surface 7. , And the rectangular surface 10 (lower maximum enlarged diameter portion 14).

  The upper maximum diameter expanded portion 13 and the lower maximum diameter expanded portion 14 that are most expanded in the can body 2 are pressing portions formed by the upper pressing surface portion 22b and the lower pressing surface portion 22f of the pressing surface 22 of each split tool 21. . Therefore, the pressing force applied to the can body 2 during the diameter expansion process gradually increases at the first taper pressing surface portion 22c and the second taper pressing surface portion 22e and becomes maximum at the upper pressing surface portion 22b and the lower pressing surface portion 22f.

  At this time, the upper pressing surface portion 22b and the lower pressing surface portion 22f are the smallest surfaces of the pressing surfaces 22, so that the contact area with the inner surface of the can body 2 is small. In this way, the upper maximum expanded portion 13 and the lower maximum expanded portion 14 that are most expanded in the can body 2 with a small contact area are formed, so that the diameter is expanded with a relatively small pressing force with respect to the expanded amount. This can facilitate the diameter expansion process.

  After the diameter-enlarged surface 7 is formed on the can body 2 by each split tool 21, each split mold is moved as shown in FIG. 3A by urging the spring member 27 by moving the columnar member 23 upward. The tool 21 is converged, and each split tool 21 in the converged state is extracted from the inside of the can body 2. Thereby, as shown in FIG.2 (b), the can body 2 provided with the enlarged diameter surface 7 is formed.

  Subsequently, the can body 2 provided with the bead 8 is formed as shown in FIG.

  The indenting process is performed by an indentation molding apparatus 28 whose main part is shown in FIG. The indentation molding apparatus 28 includes a first holding member 29 that comes into airtight contact with one end opening side of the can body 2, a second holding member 30 that comes into airtight contact with the other end opening side of the can body 2, and the can body 2. And a pressing roller 31 that presses a part of the outer peripheral surface.

  The first holding member 29 is provided so as to be rotatable about the same axis as the axis of the can body 2 and to be movable back and forth along the axial direction of the can body 2. The first holding member 29 is provided with an air introduction port 32 for introducing air toward the inside of the can body 2. Although not shown, the recess molding apparatus 28 includes an advancing / retreating drive unit that moves the first holding member 29 forward and backward, and an air supply unit that is connected to the air introduction port 32 and supplies air of a predetermined pressure.

  The second holding member 30 is connected to a rotation shaft 33 provided in a rotation driving means (not shown), and is rotated about the same axis as the axis of the can body 2 through the rotation shaft 33 by driving of the rotation driving means.

  The pressing roller 31 is provided so as to be movable up and down toward the can body 2, and presses against the can body 2 by being lowered so that the can body 2 is recessed. Although not shown, the indentation molding device 28 includes elevating means for elevating the pressing roller 31.

  When forming the bead 8 by recessing in the can body 2 using the indentation molding device 28, first, the can body 2 is sandwiched between the first holding member 29 and the second holding member 30. Next, air is introduced into the can body 2 through the air introduction port 32 of the first holding member 29. At this time, the pressure of the air introduced into the can body 2 is maintained by the air supply means until the bead 8 is formed.

  Subsequently, the second holding member 30 is rotated by the rotation driving means. At this time, the can body 2 rotates because the first holding member 29 is rotatably provided. In this state, the pressing roller 31 is lowered and the outer peripheral surface of the can body 2 is pressed to be deformed in a concave manner. The can body 2 rotates in a state where it is pressed by the pressing roller 31, whereby a recessed deformation portion extends over the entire circumference of the can body 2, and the can body 2 including the beads 8 as shown in FIG. Is formed.

  In this embodiment, the bead 8 is formed on the can body 2 using the indentation molding apparatus 28 having the above-described configuration, but an indentation molding apparatus having another configuration may be used. Moreover, in this embodiment, after forming the enlarged diameter surface 7 by the diameter expansion process with respect to the can body 2, the bead 8 by the indentation process was formed, but it is not restricted to this, For example, it does not illustrate However, the diameter-expanded surface 7 and the bead 8 may be simultaneously formed on the can body 2 by using an apparatus that can perform the diameter-expanding process and the recessing process simultaneously.

  Further, in the present embodiment, as shown in FIG. 1, the paneling strength of the can body 2 is improved by forming the bead 8 in the intermediate unexpanded portion 17 of the can body 2. In addition to this, a bead may not be formed in the intermediate unexpanded portion 17 of the can body 35 as in the can 34 shown in FIG. Also in this case, the can body 35 includes the enlarged surface 7 having the above-described configuration, and the intermediate unexpanded portion 17 is a portion having a relatively large thickness, so that a decrease in paneling strength is suppressed. . And according to this, the process of forming a bead in the can body 35 can be omitted, and the manufacturing cost can be reduced.

  Further, in the present embodiment, as shown in FIG. 1, the upper end unexpanded portion 15 and the lower end unexpanded portion 16 of the can body 2 are shown in which the outer diameter before the diameter expansion processing is maintained. However, the present invention is not limited thereto, and although not shown, neck-in processing may be performed on one or both of the upper end unexpanded portion 15 and the lower end unexpanded portion 16 of the can body 2.

  DESCRIPTION OF SYMBOLS 1,34 ... Can body, 2,35 ... Can body, 3 ... Canopy, 4 ... Bottom lid, 5 ... Upper winding part (clamping part), 6 ... Lower winding part (clamping part), 7 ... Expansion Diametrical surface, 8 ... bead, 13 ... upper maximum expanded portion, 14 ... lower maximum expanded portion, 15 ... upper end unexpanded portion, 16 ... lower end unexpanded portion, 17 ... intermediate unexpanded portion, 18 ... first DESCRIPTION OF SYMBOLS 1 taper wall part, 19 ... 2nd taper wall part, 21 ... Split tool, 22 ... Pressing surface, 22b ... Upper pressing surface part, 22c ... 1st taper pressing surface part, 22d ... Non-pressing part, 22e ... 2nd taper pressing Surface part, 22f ... Lower pressing surface part.

Claims (5)

A cylindrical can body extending in the height direction, a canopy wound around the upper end of the can body, and a bottom lid wound around the lower end of the can body, and expanded at a predetermined position of the can body In a can body having a can height of 80 mm to 110 mm, which is a dimension from the upper edge of the canopy to the lower edge of the bottom lid,
The can body is located at the upper part, the upper maximum diameter-expanded part expanded to the maximum outer diameter by the diameter-expanding process, and at the lower part, the maximum part of the lower part expanded to the maximum outer diameter by the diameter-expanding process An enlarged diameter portion, an intermediate unexpanded portion positioned between the upper largest enlarged portion and the lower largest enlarged portion and not enlarged, and the upper largest enlarged portion from the intermediate unexpanded portion The first taper wall portion formed by the diameter expansion process formed into a shape gradually increasing in diameter and the diameter expansion formed in a shape gradually increasing from the intermediate unexpanded portion to the lower maximum diameter expanded portion. A second tapered wall by machining,
The can body before the diameter expansion processing is formed to have an outer diameter of 46.0 mm to 50.8 mm by any metal plate having a thickness of 0.15 mm to 0.20 mm,
The upper maximum diameter expansion portion and the lower maximum diameter expansion portion are expanded to an outer diameter of 3% to 14% with respect to the outer diameter of the can body before the diameter expansion processing. Characteristic can body. A non-expanded upper end non-expanded portion is provided between the upper maximum enlarged portion and the canopy tightening portion, and the upper end unexpanded portion from the upper edge of the canopy tightening portion is provided below. The distance to the edge is 4mm-9mm,
A lower end unexpanded portion that is not expanded is provided between the lower maximum enlarged portion and the bottom lid winding portion, and a lower end unexpanded portion from a lower edge of the bottom lid winding portion. The can body according to claim 1, wherein the distance to the upper edge is 4 mm to 9 mm.   3. The can body according to claim 1, wherein the can body includes an annular bead that is recessed in the circumferential direction of the can body at the intermediate unexpanded portion. 4. The can body is inserted into the can body with a plurality of split mold tools in a converged state, and then each split tool is moved radially outward so that the pressing surface of each split tool is used to press the can body. Expanded molding that presses the inner peripheral surface is performed, and a plurality of diameter-enlarged surfaces that extend in the height direction with a predetermined interval along the circumferential direction correspond to the pressing surface of each split tool in the expanded molding. Formed,
The diameter-expanding surface forms the upper maximum diameter-expanded portion, the lower maximum diameter-expanded portion, the intermediate unexpanded portion, the first tapered wall portion, and the second tapered wall portion. Item 4. The can according to any one of Items 1 to 3. In the split tool, the first pressing surface includes the upper pressing surface portion that forms the upper maximum diameter expanding portion, the lower pressing surface portion that forms the lower maximum diameter expanding portion, and the upper pressing surface portion. A first taper pressing surface portion that forms a tapered wall portion; a second taper pressing surface portion that forms the second taper wall portion continuously with the lower pressing surface portion; and the first taper pressing surface portion and the second taper pressing surface portion. And the non-pressing portion that forms the intermediate unexpanded portion, and the upper pressing surface portion and the lower pressing surface portion when the circumferential direction of the can body is the width direction of the pressing surface Is a shape that is smaller in width than the non-pressing portion and extends in the vertical direction with the width dimension being constant, and the first taper pressing surface portion gradually increases in width from the upper pressing surface portion toward the non-pressing portion. The second taper push Surface portion which progressively width towards the non-pressing portion from said lower pressing surface is to become a large shape is used,
The can body according to claim 4, wherein the diameter-enlarging surface of the can body is formed in a shape corresponding to the shape of the pressing surface when the diameter-enlargement processing is performed by pressing the pressing surface.