JPH0796138B2 - Seamless can manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seamless can used for beer cans, carbonated drinks cans and the like, and a method for producing a seamless can having a bottom portion with improved pressure resistance.

[0002]

2. Description of the Related Art An outer wall portion that extends diagonally inward and downward in a radial direction,
Inner pressure resistance of the bottom portion of a seamless metal can, which has an annular protrusion consisting of an inner wall portion connected to the outer wall portion through a ground portion, and a bottom portion having a center panel inside thereof, that is, buckling resistance, is the lateral width of the ground portion. It is known that the smaller is the higher. In the present specification, the ground portion refers to a curved portion that connects the outer wall portion and the inner wall portion, and the lateral width of the ground portion,
The width w of the grounding portion 14 'cut by the plane 35 parallel to the grounding surface 34 (see FIG. 5) passing through the lowest position of the inner surface of the grounding portion. The lateral width w is proportional to the radius of curvature when the radius of curvature of the cross section of the ground contact portion is uniform.

As a method of forming such a bottom portion, it is conceivable to perform press molding using a punch having a small cross-sectional curvature radius of the nose portion which comes into contact with the inner surface of the ground portion, but in this case, the nose portion is damaged. Easy, especially when the bottom is thin (for example, about 60 to 170 μm), the grounding portion during molding,
Alternatively, the curved portion connecting the inner wall portion and the central panel may be broken, or the portion from the ground portion to the inner wall portion and the curved portion may be extended and deformed to be thin, and the organic film on the inner surface may be easily damaged. As a result, the inner wall portion is likely to protrude downward, and therefore, the problem that the internal pressure resistance is likely to be lowered easily occurs.

On the other hand, the width of the ground contact portion is relatively large,
In addition, a bottom portion having a relatively large angle with the axial center of the inner wall portion is formed in advance, the inner wall portion is held by a cylindrical body, and a roll having a truncated conical surface is applied to the outer wall portion to form a can and a roll. A so-called spinning method has been proposed, which causes rolling during the period (Japanese Patent Publication No. 1-50493). But this method
When the outer surface organic film of the outer wall portion is damaged due to friction during rolling, and when the body portion is thin (for example, about 60 to 170 μm), the body portion is likely to be deformed such as twisted.

[0005]

SUMMARY OF THE INVENTION According to the present invention, there is provided an inner wall portion having an outer wall portion directed obliquely downward inward in a radial direction and an annular projection portion having an inner wall portion connected to the outer wall portion through a grounding portion having a relatively small lateral width. A seamless can having a bottom with improved properties is used to break the punch, break the ground part, deform the body, damage the organic film on the inner surface from the ground part to the curved part, or the organic film on the outer surface of the outer wall. It is an object of the present invention to provide a method for producing a seamless can, which is particularly suitable for a case where the body or bottom of the can is thin and which can be produced without causing damage to the can.

[0006]

According to the invention of claim 1,
The manufacturing method of the seamless can whose width of the grounding part is narrowed,
A preform can having an outer wall portion that is concave inward in the radial direction and has a circular arc-shaped cross section, and an annular protrusion portion that has a frustoconical inner wall portion that connects to the outer wall portion through a ground portion, and a bottom portion that has a central panel. More, in the method of manufacturing a seamless can in which the lateral width of the grounding portion is narrowed, a closing tool is brought into contact with the end surface of the open end, and the lower end of the outer wall portion is attached to the supporting surface of the ring die having the inverted truncated cone-shaped supporting surface. While abutting and bringing the closure and the ring die close to each other, the pressurized fluid is introduced into the preform can through the guide hole of the closure to form the outer wall portion so as to extend along the supporting surface and the inner wall. It is characterized in that the portion is raised in a cylindrical shape.

According to a second aspect of the present invention, there is provided a method for manufacturing a seamless can in which a lateral width of a grounding portion is narrowed, the outer wall portion having a concave arc-shaped cross section, and a truncated cone shape connected to the outer wall portion through the grounding portion. An annular protrusion having an inner wall portion, and a preform can having a bottom portion having a central panel, in a method for producing a seamless can in which the width of the ground portion is narrowed,
The closure is brought into contact with the end face of the opening end, the outer wall is brought into contact with the support surface of the hold down ring having a support surface having a shape corresponding to the outer wall, and a truncated cone shape having a slightly larger inclination angle than the inner wall is formed. While bringing the core punch and the closure close to each other, the pressurized fluid is fed into the preform can through the guide hole of the closure to press the inner wall portion radially outward by the truncated cone shape of the core punch. It is characterized in that it is formed so that the inclination angle of the inner wall portion becomes large.

According to a third aspect of the present invention, there is provided a method for manufacturing a seamless can in which a lateral width of a grounding portion is narrowed, an outer wall portion which is directed radially inward and downward, extends linearly in cross section, or is concave in arcuate cross section, And a method for producing a seamless can in which the lateral width of the ground portion is narrowed from a preform can having an annular protrusion having an inner wall portion of a truncated cone shape connected to the outer wall portion via a ground portion, and a bottom portion having a central panel In, the abutment is brought into contact with the end face of the open end, the outer wall is brought into contact with the support face of the ring die having the support face having the shape corresponding to the outer wall, and the upper face having the shape corresponding to the cylindrical portion and the central panel is provided. With the upper surface of the hold-down core in contact with the central panel, the pressurized fluid is fed into the preform can through the guide hole of the closing tool, and the central panel is pushed down together with the inner wall to support the supporting surface. Characterized by fitting the lower end and hold down the core lower part near the material of the inner wall portion in the gap between the cylindrical portion of the.

According to a fourth aspect of the present invention, there is provided a method for manufacturing a seamless can in which the width of the ground contact portion is narrowed. In a method for producing a seamless can having a narrowed width of a grounding part from a preform can having an annular protrusion having a cylindrical inner wall portion connected to each other and a bottom having a central panel, the end face of the opening end is closed. Of the hold-down core having a cylindrical portion and an upper surface having at least a peripheral edge corresponding to the central panel, and an outer wall portion abutting on the supporting surface of the ring die having a supporting surface having a shape corresponding to the outer wall portion. While pressing the upper surface against the center panel and bringing the closure and the ring die close to each other, the pressurized fluid is fed into the preform can through the guide hole of the closure to push the center panel together with the inner wall. Gaité, characterized by fitting the lower portion near the material of the inner wall portion in the gap between the cylindrical portion of the lower end and hold down the core of the support surface.

The closure includes an outer cylinder and a core having a guide hole for feeding pressurized fluid, and the core has an outer body whose lower surface of an end edge portion is in contact with an end surface of the opening end portion, and an inside of the opening end portion. It preferably has an insertable inner body, the inner diameter of the outer cylinder is substantially equal to the outer diameter of the open end, and the outer cylinder is preferably slidable along the outer peripheral surface of the outer body.

[0011]

In the case of the invention according to claim 1, since the closing tool that abuts on the end face of the open end of the preform can and the ring die that abuts on the lower end of the outer wall portion come close to each other, the shaft is attached to the body of the preform can. Although a pressing force is applied in the direction, at the same time, since the pressurized fluid is sent into the can through the guide hole of the closing tool, even if the body is thin due to the internal pressure, deformation such as buckling does not easily occur. Then, due to the pressing and the internal pressure, the outer wall portion which is recessed in an arcuate cross section linearly extends along the inverted frustoconical support surface of the ring die, and the frustoconical inner wall portion rises in a short cylindrical shape. , The width of the ground contact part becomes narrower.

Also in the case of the invention according to claim 2, since the closing tool abutting against the end face of the open end of the preform can and the core punch are brought close to each other, a pressing force in the axial direction is applied to the body of the preform can. At the same time, since the pressurized fluid is fed into the can through the guide hole of the closure, the internal pressure prevents the deformation such as buckling even if the body is thin. Due to the above approach, the truncated cone-shaped portion of the core punch having the truncated cone-shaped portion having a slightly larger inclination angle than the truncated cone-shaped inner wall portion presses the inner wall portion outward in the radial direction, but the outer wall portion is the outer wall portion. Since it is in contact with the supporting surface of the hold-down ring having a supporting surface having a shape corresponding to, it is immovable in the radial direction. Therefore, the inner wall is shaped so that its inclination angle is slightly larger,
The width of the ground contact part is reduced.

In the case of the invention according to claim 3, since the axial pressing force is not applied to the body portion of the preform can, only the pressurized fluid is fed into the can through the guide hole of the closure. Even if the body is thin, it is difficult to cause deformation such as buckling. The outer wall portion is in contact with the support surface of the ring die having the support surface having the shape corresponding to the outer wall portion, and the upper surface of the cylindrical portion and the holddown core having the upper surface having the shape corresponding to the center panel are in contact with the center panel. At, the inner pressure of the pressurized fluid pushes down the central panel with the frustoconical inner wall. In this case, the inner wall portion becomes a cylindrical shape in close contact with the cylindrical portion, and the material near the lower portion of the cylindrical inner wall portion fits into the gap between the lower end of the support surface and the cylindrical portion of the holddown core. , A ground portion having a reduced width is formed.

Also in the case of the invention according to claim 4, since the closing die which abuts on the end face of the open end of the preform can and the ring die which abuts on the outer wall are brought close to each other, the pressing force is applied to the body of the preform can. However, since the pressurized fluid is sent into the can through the guide hole of the closing tool at the same time, even if the body is thin due to the internal pressure, deformation such as buckling is unlikely to occur. By the above pressure and internal pressure,
The center panel and the inner wall of the cylindrical shape are pushed down together with the hold-down core, while the outer wall which is recessed in an arc shape in cross section extends linearly in cross section along the inverted frustoconical support surface of the ring die and the lower end of the support surface. Since the material in the vicinity of the lower portion of the inner wall portion is inserted into the gap between the cylindrical portion of the hold-down core and the hold-down core, a grounding portion having a narrowed width is formed.

In each of the above inventions, the radius of curvature of the inner surface of the ground portion of the preform can may be relatively large, so that the reduction in the thickness of the material when forming the bottom is suppressed, and the organic film on the inner surface is also damaged. Hard to get up. Further, in the step of narrowing the ground contact portion, a punch that contacts the inner surface of the ground contact portion is not used. Therefore, there is no risk of damage to the punch during molding. Further, when the ground contact portion is narrowed, bending deformation is mainly applied to the ground contact portion, and extension deformation is not substantially applied. Therefore, there is no possibility of breaking the grounding portion during molding. Furthermore, the slippage between the outer surface of the outer wall portion and the tool is only once at most, and unlike the spinning method, rolling is not performed several times. Also, when the bottom is thin, the deformation resistance of the outer wall, and thus the friction resistance, is also small. Therefore, there is little risk of damage to the outer surface organic film of the outer wall portion.

Since the closing tool according to the fifth aspect comprises the outer cylinder and the core having the guiding hole for feeding the pressurized fluid, the pressurized fluid is passed through the guiding hole and inside the preform can during molding. Can be sent to. The core has an outer body whose lower surface of the end edge can contact the end surface of the opening end, the inner diameter of the outer cylinder is substantially equal to the outer diameter of the opening end, and the outer cylinder is the outer circumference of the outer body. Since it is slidable along the surface, if pressurized fluid is fed in with the outer cylinder lowered, the outer cylinder and the open end will come into close contact with each other over a relatively large area, so leakage of the pressurized fluid will occur. Can be prevented.
After molding, the seamless can can be easily fed from the tool by raising the outer cylinder.

[0017]

1 and 2, a body portion 12, an outer wall portion 13 'which is recessed inward with a relatively large radius of curvature in a circular arc-shaped cross section facing inward in the radial direction, and a ground portion 1 on the outer wall portion 13'.
Preform can 11 with an annular projection 16 'having a frustoconical inner wall 15' connecting via 4 ', and a bottom 18 having a central panel 17 recessed in an arcuate cross section.
3 illustrates an example of a method of forming (FIG. 2). In FIG. 1, reference numeral 1 denotes a cup-shaped body formed by drawing and redrawing a circular blank of a metal plate (usually coated on both sides with an organic film). The cup-shaped body is a cylindrical body portion 2 and a radius portion. 3 and a flat bottom 4. As the metal plate, tin-free steel, tin-plated steel plate, aluminum (alloy) thin plate or the like having a thickness of about 60 to 170 μm is preferably used.

Preform can 11 from cup-shaped body 1
Is formed by a bottom forming punch 5, a lower part of which is a ring-shaped part 6, a hold-down ring 7, and a doming die 8.
And a bottom forming tool consisting mainly of the retainer 9. The bottom molding punch 5 has an outer diameter that allows it to be fitted almost snugly into the body 2. On the lower portion of the ring-shaped portion 6, a sloped portion 6a having a shape corresponding to the inner surface of the outer wall portion 13 'and a nose portion 6b having a shape corresponding to the inner surface of the ground contact portion 14' are formed. The radius of curvature r ₁ of the nose portion 6b is relatively large (e.g., 0.3 to 3 mm) so as not to again damage to mold the grounding portion 14 'are defined.
An air guide hole 5a penetrates through the bottom molding punch 5.

The hold down ring 7 is urged upward by a spring (not shown) provided between the frame (not shown) and the shaft 7a so that the upper surface 7b thereof is always kept at its upper surface 7b as shown in FIG. It is in a position engaged with the fixed retainer 9. Inner surface 7 of holddown ring 7
c is composed of an upper short cylindrical portion 7c1 having an inner diameter slightly larger than the outer diameter of the body 2, a sloped portion 7c2 and a lower short cylindrical portion 7c3 below the upper short cylindrical portion 7c1. The inclined surface portion 7c2 has a shape corresponding to the outer surface of the outer wall portion 13 'to be formed. The inner diameter of the lower short cylindrical portion 7c3 is set to be slightly larger than the outer diameter of the tubular portion 8b of the doming die 8.

The doming die 8 is fixed to a frame (not shown), and the upper surface thereof is a molding surface 8a having a curved surface having a shape corresponding to the outer surface of the central panel 17, which is larger than the inner diameter of the ring-shaped portion 6. A cylindrical tube portion 8b having a slightly smaller diameter is connected to the upper surface 8a.

With the above tools, the preform can 11
Is formed as follows. As shown in FIG. 1, when the bottom molding punch 5 on which the cup-shaped body 1 is externally inserted is lowered by, for example, a crank mechanism (not shown), the radius portion 3 comes into contact with the hold down ring 7,
When pressing force is applied to the radius portion 3 and the hold down ring 7 descends to reach the bottom dead center, as shown in FIG. 2, the outer wall portion 13 ′ is cooperated with the ring portion 6 and the hold down ring 7. Is formed. At the same time, the bottom portion 4 is pushed in by the doming die 8 so that the radius of curvature of the inner surface is equal to the radius of curvature r ₁ of the nose portion 6b of the ring-shaped portion 6.
4 ', a frusto-conical inner wall portion 1 that slightly inclines upward inward
5'and a central panel 17 with an arcuate cross section is formed.
As described above, the annular protrusion 16 ′ and the central panel 17
The preform can 11 including the bottom portion 18 and the body portion 12 is formed.

In order to form the preform can 11 having the outer wall portion 13 "(FIG. 10) extending linearly in cross section, the sloped portion 6a of the ring-shaped portion and the slope portion 7c2 of the holddown ring are respectively formed on the outer wall portion 13. The shape may correspond to the inner and outer surfaces of ". Also, the cylindrical inner wall portion 15 "
In order to form the preform can 11 having (FIG. 13), the diameter of the tubular portion 8b of the doming die 8 is simply made equal to the inner diameter of the ring-shaped portion 6-2t (t is the plate thickness of the bottom portion 4). Good.

3 and 4 show steps of an embodiment of the invention according to claim 1. In FIG. 3, 20 is a closing tool for closing the open end 12a of the body 12 of the preform can 11, 26 is a ring die fixed to the frame 31, and 28 is urged upward by a spring 29. It is a hold-down core that supports the central panel 17. The closure 20 includes a core 21 and an outer cylinder 22. The core 21 includes an inner body 23 having a diameter slightly smaller than the inner diameter of the open end 12a, and an outer body 24 having a diameter substantially equal to the outer diameter of the open end 12a.

The core 21 has a guide hole 25 for introducing a pressurized fluid (usually pressurized air) into the preform can 11.
Has penetrated. The inner diameter of the outer cylinder 22 is substantially equal to the outer diameter of the opening end 12a, so that the opening end 12a can be fitted into the outer cylinder 22 exactly. Moreover, the outer cylinder 22 is slidable along the outer peripheral surface 24a of the outer body 24. In a state where the outer cylinder 22 is lowered (FIG. 3), a gap portion 19 having a gap width slightly larger than that of the opening end portion 12a is formed between the outer cylinder 22 and the inner body 23. The end face 12b of the opening end 12a inserted into the gap 19 is the bottom face 2 of the end edge of the outer body 24.
Contact 4b.

The inner surface 27 of the ring die 26 is connected to the upper short cylindrical portion 27a having an inner diameter slightly larger than the outer diameter of the body portion 12, a frustoconical support surface 27b therebelow, and a lower end 27b1 of the support surface 27b. Curved portion 27c and lower short cylindrical portion 2
Mainly from 7d. The inner diameter of the lower short cylindrical portion 27d is set to be slightly larger than the outer diameter of the holddown core 28. The diameter at the lower end 27b1 of the support surface is substantially equal to the diameter at the outer upper end 14'a of the grounding portion 14 '. The hold-down core 28 has a cylindrical portion 28b having a cylindrical side surface 28b1 and an upper surface 28a whose peripheral portion has a truncated arc shape in cross section corresponding to the outer surface of the central panel 17.
Is equipped with. The hold-down ring core 28 is always in the position shown in FIG. 3 with the bolt head 30 engaged with the frame 31, and the center panel 1 of the preform can 11 is held.
When 7 is placed on the hold-down core 28, the outer upper end 14'a of the ground contact portion comes into contact with the lower end 27b1 of the supporting surface.

As shown in FIG. 3, the center panel 17 of the preform can 11 is placed on the hold-down core 28, and the outer upper end 14'a of the grounding portion is brought into contact with the lower end 27b1 of the supporting surface to close it. With the bottom surface of the gap portion 19 of the tool 20, that is, the lower surface 24b of the outer edge of the outer body abutting the end surface 12b of the open end, the closing tool 20 is brought close to the ring die 26 to press the preform can 11. Meanwhile, the pressurized air 32 (usually about 5-6 atm) is sent through the guide hole 25. Grounding part 1
4'is pushed inward in the radial direction by the inner surface 27 of the ring die 26, and at the same time, the outer wall portion 13 'is depressed in an arcuate cross section.
Is pressed outward by the internal pressure. Therefore, the outer wall 1
As shown in FIGS. 4 and 5, 3'is a truncated cone-shaped support surface 2
7b extends linearly in cross section, the grounding portion 14 'moves slightly inward in the radial direction, and at the same time, the inner wall portion 15' closely contacts the slightly lowered cylindrical side surface 28b of the holddown core 28 to form a cylindrical shape. Become. As a result, the seamless can 10 having the grounding portion 14 whose width is narrowed is manufactured.

Since the opening end 12a is pushed outward in the radial direction by the pressurized air 32 and comes into close contact with the inner surface of the outer cylinder 22 in a relatively wide area, the pressurized air is unlikely to leak.
After the molding is completed, the pressurized air 32 is discharged to release the internal pressure, the closing tool 20 is raised, the seamless can 10 is pulled out from the holddown core 28, and the outer cylinder 22 is further pulled out.
After being lifted along with and pulled out from the open end 12a, the seamless can 10 is sent to the next step by a gripping tool (not shown). Note that, as shown in FIG. 6, the holddown core 28 does not necessarily have to be used. However, in this case, the degree of narrowing of the width of the ground portion 14 ′ is slightly smaller than that when the hold-down core 28 is used.

7 and 8 show steps of an embodiment of the invention according to claim 2. In FIG. 7, 41 is a disk-shaped closure having a guide hole 42 for blowing the pressurized air 32,
Reference numeral 43 is a core punch fixed to the frame 44, and 45 is a holddown ring. An annular groove 41 a for inserting the open end 12 of the preform can 11 is formed in the closing tool 41. The core punch 43 includes an upper surface 43a having a shape corresponding to the outer surface of the central panel 17 of the preform can 11, a truncated cone shape portion 43b having a side surface 43b1 having an inclination angle and height slightly larger than those of the inner wall portion 15 ', and a diameter. Has a cylindrical portion 43c slightly larger than the lower end diameter of the inner wall portion 15 '.

The inner surface of the hold-down ring 45 has an upper short cylindrical portion 45 having an inner diameter slightly larger than the outer diameter of the body portion 12.
a, a supporting surface 45b that is convexly curved inward toward the inner surface of the cross-sectional shape corresponding to the outer surface of the outer wall portion 13 'therebelow, and a lower short cylindrical portion 45c having an inner diameter slightly larger than the cylindrical portion 43c of the core punch. ing. The hold down ring 45 is normally urged upward by a spring 47, and its upper limit position is determined by the bolt head 46 engaging with the frame 44.

As shown in FIG. 7, the end face 12b of the body portion is brought into contact with the closing tool 41, and the outer wall portion 13 'is placed on the support surface 45b of the hold down ring 45 to guide the closing hole of the closing tool 41. When the closing tool 41 is brought close to the core punch 43 and the preform can 11 is pressed while blowing the pressurized air 32 from 42, the outer wall portion 13 ′ descends together with the hold down ring 45 as shown in FIG. 8. , Top 4 of core punch
3a and the central panel 17 are in contact with each other. Since the inclination angle of the side surface 43b1 of the truncated cone-shaped portion of the core punch is larger than that of each inner wall portion 15 ', the inner wall portion 15' is pressed inward in the radial direction, and the inner wall portion 15 'is substantially aligned with the inclination angle of the side surface 43b1. Although the vicinity of the lower end moves until the inclination angles become equal, the outer wall 1
3'is constrained by the hold down ring 45 and is immovable in the radial direction.

Therefore, as shown in FIGS. 8 and 9, the seamless can 10 is manufactured in which the width of the ground portion 14 is narrowed. The outer wall portion may have an inverted truncated cone shape extending linearly in cross section. Further, instead of the closure 41, the closure 20
Is more preferable from the viewpoint of preventing leakage of pressurized air.

FIGS. 10 and 11 show an embodiment of the invention according to claim 3. The closure 50 has an outer diameter substantially equal to the inner diameter of the open end 12a of the preform can 11,
A core 51 that can be fitted exactly into the open end 12a and an outer cylinder 52 that can slide along the core 51 are provided. Core 5
1 is provided with a guide hole 53 for feeding the pressurized air 32. Reference numeral 54 is a ring die fixed to a frame 55, the inner surface of which is an upper short cylindrical portion 54a having an inner diameter slightly larger than the outer diameter of the body portion 12, and the outer wall portion 1 below it.
A support surface 5 having a shape corresponding to an outer surface of 3 "and having an inverted truncated cone shape
4b, a recess 54c in the peripheral portion of the shallow plate connected to the lower end 54b1, and a lower short cylindrical portion 54d having an inner diameter slightly larger than the outer diameter of the central panel 17.

The lower end 54b1 of the support surface 54b extends almost below the lowest portion 14'b of the grounding portion when the preform can 11 is placed on the ring die 54. 5
Reference numeral 5 denotes a holddown core, which has an upper surface 55a and a cylindrical portion 55b each having a shape corresponding to the central panel 17. The hold-down core 55 always has a spring 56.
By the engagement of the bolt head 58 with the frame 55 so that the central panel 17 simultaneously contacts the upper surface 55a when the outer wall portion 13 "contacts the support surface 54b. The upper limit position is defined.

As shown in FIG. 10, the outer wall portion 13 "and the central panel 17 are provided with a support surface 54b and an upper surface 5 respectively.
5a, the end surface 12b of the opening end is brought into contact with the lower surface of the outer cylinder 52 of the closing tool, and the pressurized air 32 is blown from the guide hole 53 of the closing tool 50. As shown in FIG. 12, the central panel 17 holds the hold-down core 5 due to the internal pressure.
5, the truncated cone-shaped inner wall portion 15 'comes into close contact with the cylindrical side surface 55b1 of the hold-down core, and the inner wall portion 1'
A short cylindrical inner wall portion 15 is formed by the upper portion of 5 '. Also, the lower portion of the inner wall portion 15 'and the ground contact portion 14'
Is fitted into the gap 57 formed by the cylindrical portion 55b and the recessed portion 54c, and is formed in the grounding portion 14 having a reduced lateral width. Then, the seamless can 10 having the grounding portion 14 whose width is narrowed is manufactured.

The outer wall portion 13 "is an outer wall portion 13 'of a type recessed in an arcuate cross section, and the supporting surface may have a shape corresponding to the outer wall portion 13'. Further, a recess 54c is particularly provided. Alternatively, the lower short cylindrical portion 54d may hang directly from the lower end 54b1 of the supporting surface.After the molding is completed, the pressurized air 32 is discharged to release the internal pressure, and the core 51 is moved to the outer cylinder 5.
The seamless can 10 can be delivered from the tool by raising the closure 50 (not shown) while sliding along 2 and raising relative. It is more preferable to use the closing tool 20 instead of the closing tool 50 from the viewpoint of preventing leakage of the pressurized air.

13 and 14 show an embodiment of the invention according to claim 4. The closure 20 and the hold-down core 28 are shown in FIG.
It has the same structure as those of the above. The ring die 60 also
The ring die 26 except that the curved portion 26c on the inner surface of the ring die 26 is a recessed portion 61c in the peripheral portion of the shallow dish.
It has the same structure as. That is, the inner surface 61 of the ring die 60 includes an upper short cylindrical portion 61a having an inner diameter slightly larger than the outer diameter of the body portion 12, and a truncated cone-shaped support surface 6 therebelow.
1b, a depression 61 connected to the lower end 61b1 of the support surface 61b
c and the lower short cylindrical portion 61d.

As shown in FIG. 13, the center panel 17 of the preform can 11 having an inner wall portion 15 ″ having a short cylindrical shape is placed on the hold-down core 28, and the outer upper end 1 of the ground portion is placed.
4'a is brought into contact with the lower end 61b1 of the supporting surface, and the end face 12b of the opening end is brought into contact with the closing tool 20.
While pressing the preform can 11 with the guide hole 25
Through the compressed air 32.

As shown in FIGS. 14 and 15, the central panel 17 descends together with the holddown core 28 by the above-mentioned pressing and internal pressure, and the outer wall portion 13 'extends linearly in cross section along the support surface 61b, and the inner wall portion A short cylindrical inner wall portion 15 is formed by the upper portion of the 15 ". The lower portion of the inner wall portion 15" and the grounding portion 14 'are fitted into a gap 63 formed by the cylindrical portion 28b and the recessed portion 61c, It is formed on the grounding portion 14 having a narrowed width. Then, the seamless can 10 having the grounding portion 14 whose width is narrowed is manufactured. Also in this case, without providing the recess 61c,
The lower short cylindrical portion 61d may directly hang from the lower end 61b1 of the support surface.

The present invention is not limited to the above embodiment, and for example, the molding tools may be arranged so as to be horizontal to perform molding.

[0040]

According to the first, second, third, and fourth aspects of the present invention, the annular projection is composed of an outer wall portion directed obliquely downward inward in the radial direction, and an inner wall portion connected to the outer wall portion through a ground portion having a relatively small lateral width. A seamless can having a bottom portion with improved internal pressure resistance, especially when the body or bottom of the can is thin, suitable for breakage of the punch, breakage of the ground portion, deformation of the body portion, inner wall from the ground portion There is an effect that it is possible to manufacture without damaging the organic film on the inner surface over the curved portion between the inner wall portion and the central panel and the organic film on the outer surface of the outer wall portion.

According to the invention of claim 5, claim 1,
When the inventions 2, 3, and 4 are carried out, there is an effect that the pressurized air sent into the can through the closure is difficult to leak.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a state immediately before molding an example of a preform can used in the present invention.

FIG. 2 is a vertical cross-sectional view showing a state immediately after molding of an example of a preform can used in the present invention.

FIG. 3 is a vertical cross-sectional view showing the state of the embodiment of the invention according to claim 1 immediately before molding.

FIG. 4 is a vertical cross-sectional view showing the state of the embodiment of the invention according to claim 1 immediately after molding.

FIG. 5 is an enlarged vertical sectional view of an essential part showing the bottom portions of the embodiment shown in FIGS. 3 and 4 immediately before and after molding.

FIG. 6 is a longitudinal cross-sectional view of a main part showing a state immediately before molding of another embodiment of the invention according to claim 1;

FIG. 7 is a vertical cross-sectional view showing a state immediately before molding of an embodiment of the invention according to claim 2;

FIG. 8 is a vertical cross-sectional view showing a state immediately after molding of an embodiment of the invention according to claim 2;

FIG. 9 is an enlarged longitudinal sectional view of an essential part showing the bottom part of the embodiment shown in FIGS. 7 and 8 immediately before and immediately after molding.

FIG. 10 is a longitudinal sectional view showing a state of an embodiment of the invention according to claim 3 immediately before molding.

FIG. 11 is a vertical cross-sectional view showing a state immediately after molding of an embodiment of the invention according to claim 3;

FIG. 12 is an enlarged longitudinal sectional view of an essential part showing the bottom parts of the embodiment shown in FIGS. 10 and 11 immediately before and after molding.

FIG. 13 is a vertical cross-sectional view showing the state of the embodiment of the invention according to claim 4 immediately before molding.

FIG. 14 is a vertical cross-sectional view showing a state immediately after molding of an embodiment of the invention according to claim 4;

FIG. 15 is an enlarged longitudinal sectional view of an essential part showing the bottom part of the embodiment shown in FIGS.

[Explanation of symbols]

 10 Seamless Can 11 Preform Can 12b End Face 13 Outer Wall 13 'Outer Wall 13' Outer Wall 14 Grounding 14 'Grounding 15 Inner Wall 15' Inner Wall 15 '' Inner Wall 16 'Annular Projection 17 Center Panel 18 Bottom 20 Closing Tool 24b End edge lower surface 25 Guide hole 26 Ring die 27b Support surface 28 Holddown core 28b Cylindrical part 32 Pressurized air 41 Closure tool 42 Guide hole 43 Core punch 43b Frustum shape part 45 Holddown ring 45b Support surface 50 Closure tool 53 Guide hole 54 Ring die 54b Support surface 54b1 Lower end 55 Hold down core 55a Upper surface 55b Cylindrical part 57 Gap 60 Ring die 61b Support surface 61b1 Lower end 63 Gap

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Claims (5)

[Claims] 1. A bottom portion having a central panel and an annular projection having an outer wall portion that is recessed inward in the radial direction and having a circular arc shape in section, and a frustoconical inner wall portion that is connected to the outer wall portion through a grounding portion. In the method of manufacturing a seamless can in which the lateral width of the grounding portion is narrowed from a preform can including, a closure is brought into contact with the end surface of the opening end, and the support surface of the ring die having a support surface of an inverted truncated cone shape is provided. While abutting the lower end of the outer wall and bringing the closure and the ring die close to each other, the pressurized fluid is fed into the preform can through the guide hole of the closure,
A method for producing a seamless can in which the lateral width of a grounding portion is narrowed, wherein an outer wall portion is formed to extend along a support surface and an inner wall portion is raised in a cylindrical shape. 2. An annular projection having an outer wall portion that is directed obliquely downward inward in the radial direction, extends linearly in cross section, or is recessed in an arc shape in cross section, and has a truncated cone-shaped inner wall portion that is connected to the outer wall portion via a grounding portion. Part, and a method of manufacturing a seamless can in which the lateral width of the grounding part is narrowed from a preform can having a bottom part having a central panel, a closure is brought into contact with the end face of the open end, and the outer wall part corresponds to the outer wall part. A core punch having a truncated cone shape having an inclination angle slightly larger than the inner wall, and a closing tool are brought close to each other while abutting against the supporting surface of the hold-down ring having a supporting surface shaped like A characteristic feature is that the pressure fluid is fed into the preform can, and the inner wall portion is pressed outward in the radial direction by the truncated cone-shaped portion of the core punch, and the inclination angle of the inner wall portion is increased. Method of manufacturing a seamless cans narrowed the width of the ground portion. 3. An annular projection having an outer wall portion that is directed radially inward and downward, extends linearly in cross section, or is recessed in an arc shape in cross section, and has a truncated cone-shaped inner wall portion that is connected to the outer wall portion via a grounding portion. Part, and a method of manufacturing a seamless can in which the lateral width of the grounding part is narrowed from a preform can having a bottom part having a central panel, a closure is brought into contact with the end face of the open end, and the outer wall part corresponds to the outer wall part. With the support surface of the ring die having a support surface of the shape, and with the upper surface of the hold-down core having the upper surface of the shape corresponding to the cylindrical portion and the central panel in contact with the central panel, Through the pressurized fluid into the preform can, pushing down the central panel together with the inner wall, and fitting the material near the lower part of the inner wall into the gap between the lower end of the supporting surface and the cylindrical part of the holddown core. Seamless can manufacturing method of the narrowed characterized, the width of the ground portion to. 4. An annular projection having an outer wall portion that is recessed in an arcuate cross-section that is directed obliquely downward inward in the radial direction, a cylindrical inner wall portion that is connected to the outer wall portion through a ground portion, and a bottom portion that has a central panel. In a method for manufacturing a seamless can having a narrowed lateral width of a ground portion from a preform can, a ring die having a supporting surface having a shape in which an outer wall portion has a shape corresponding to the outer wall portion by abutting a closing tool on the end surface of the opening end portion. Of the hold-down core having a cylindrical portion and at least a peripheral edge of the hold-down core abutting against the supporting surface of the central panel, and at the same time bringing the closing tool and the ring die close to each other, the closing tool Pressurized fluid is fed into the preform can through the guide hole, and the central panel is pushed down together with the inner wall part, and the lower part of the inner wall part is inserted in the gap between the lower end of the supporting surface and the cylindrical part of the holddown core. Characterized by fitting the material beside method of seamless cans narrowed the width of the ground portion. 5. The closure includes a core having an outer cylinder and a guide hole for feeding pressurized fluid, the core has an outer body whose lower surface of an end edge portion is in contact with an end surface of the opening end, and an opening end. And an inner body that can be inserted into the outer cylinder, the inner diameter of the outer cylinder is substantially equal to the outer diameter of the open end, and the outer cylinder is slidable along the outer peripheral surface of the outer body. The method for producing a seamless can according to claim 1, 2, 3, or 4 in which the lateral width of the ground portion is narrowed.