JP2019013948A - Can bottom forming device - Google Patents

Abstract

To provide a can bottom forming device which can stabilize machining accuracy of a recessed part formed on a can bottom irrespective of an operation speed of the device.SOLUTION: A can bottom forming device 10 forms a recessed part by pressing at least one of an inner peripheral wall and outer peripheral wall of an annular protrusion part of a can bottom of a can W, and includes: a star wheel 13 for holding a can body of the can W; a can bottom forming unit 14 which has a spindle shaft C extending so as to coincide with a can axis of the can W held on the star wheel 13; a rotation shaft 12 on which the star wheel 13 and the can bottom forming unit 14 are mounted; a first drive source 41 which rotates the rotation shaft 12 around a center axis O of the rotation shaft 12; a press roller 20 which is included in the can bottom forming unit 14, reciprocates in a radial direction with respect to the can bottom of the can W, rotates around the spindle shaft C to form the recessed part, which extends in a circumferential direction, on the annular protrusion part; and a second drive source 42 which rotates the press roller 20 around the spindle shaft C.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a can bottom forming apparatus that performs a bottom reforming process on a can bottom of a can.

  In recent years, there has been a demand for weight reduction of cans such as aluminum cans, and it is effective to reduce the thickness (thickness) of the cans. However, if the thickness of the can is simply reduced, deformation such as bottom growth and buckling tends to occur on the bottom of the can. The bottom growth is a phenomenon in which the annular convex portion (rim) of the can bottom is deformed by an increase in the internal pressure of the can in which the contents are enclosed. When bottom growth occurs, the height of the can (the total length in the can axis direction) changes, causing problems in manufacturing and shipping. Buckling is a phenomenon in which the dome portion of the bottom of the can is inverted when the internal pressure of the can exceeds the pressure strength.

For the purpose of preventing such deformation of the bottom of the can, for example, bottom reforming (bottom profile reformer processing, BPR processing) using a can bottom forming apparatus has been proposed as shown in Patent Document 1 below.
A can bottom forming apparatus includes: a star wheel that holds a can body of a can; a can bottom forming unit having a spindle axis (spindle central axis) that extends to coincide with a can axis of a can held by the star wheel; And a rotating shaft to which the can bottom forming unit is attached, and a driving motor (driving source) for rotating the rotating shaft around its central axis.
Further, the can bottom forming unit is reciprocally moved in the radial direction with respect to the can bottom, a top support member that supports the open end of the can body of the can held by the star wheel, a bottom support member that supports the can bottom, and And a pressing roller that rotates around the spindle axis and presses the inner peripheral wall of the annular convex portion of the can bottom and forms a groove-shaped concave portion extending in the circumferential direction.

The drive motor rotates (revolves) the star wheel, the can held by the star wheel, and the can bottom forming unit (hereinafter abbreviated as the can bottom forming unit) around the central axis of the rotation shaft. In addition, a driving gear and a driven gear are connected to the pressing roller, and when the can bottom forming unit or the like revolves around the central axis of the rotating shaft, the pressing roller rotates around the spindle axis (can It can also be rotated (revolved). The pressure roller is rotatable around the central axis of the pressure roller.For this reason, when the pressure roller is revolved around the spindle axis as described above while being pressed against the inner peripheral wall of the annular convex portion, The pressing roller rolls on the inner peripheral wall while rotating (spinning) around its central axis.
In this way, the bottom reforming unit or the like revolves around the central axis of the rotating shaft, and the pressing roller revolves around the spindle axis of the can bottom forming unit, so that the bottom reforming is performed on the can bottom of the can held by the star wheel. Processing is performed to form a recess. Then, by forming the recess in the can bottom, the strength of the can bottom is increased, and deformation such as bottom growth and buckling is suppressed.

US Pat. No. 5,704,241

The conventional can bottom forming apparatus has the following problems.
For example, by increasing the number of rotations of the drive motor, it is possible to increase the speed at which the can bottom forming unit or the like is rotated about the central axis of the rotation shaft, thereby improving the production efficiency. However, when the rotational speed around the central axis of the rotating shaft of the can bottom forming unit or the like is increased, the rotational speed around the spindle axis of the pressing roller is increased accordingly. As a result, the pressing roller accompanying an increase in centrifugal force around the spindle axis Due to the extension of the link mechanism, the influence of speed dependency, etc., the depth (molding amount) of the recess formed in the can bottom becomes deep.

  In other words, since the depth of the recess also changes according to the speed at which the can bottom forming unit etc. is rotated around the central axis of the rotating shaft, the pressure resistance of the can bottom changes depending on the operating speed of the apparatus, and the quality of the can varies. Occurs. Specifically, the pressure resistance of the can bottom increases as the depth of the recess increases, and the pressure resistance of the can bottom decreases as the depth of the recess decreases. For example, when the amount of change in the depth of the recess is 0.5 mm (1.0 mm in the amount of change in the BPR inner diameter (diameter)), the pressure resistance of the can bottom changes by about 130 kPa.

  The present invention has been made in view of such circumstances, and is formed on the bottom of the can regardless of the operation speed of the apparatus (corresponding to the rotational speed around the central axis of the rotation axis of the can bottom forming unit or the like). An object of the present invention is to provide a can bottom forming apparatus that can stabilize the processing accuracy of the concave portion to be formed.

  One aspect of the present invention includes a dome portion that is recessed upward in the can axis direction, and a peripheral edge portion of the dome portion. And an annular convex portion that protrudes downward in the can axis direction and extends around the can axis, and is depressed by pressing at least one of the inner peripheral wall and the outer peripheral wall of the annular convex portion. A can bottom forming apparatus for forming a can bottom, wherein the can bottom forming unit has a star wheel for holding the can body of the can and a spindle shaft extending to coincide with the can axis of the can held by the star wheel. A rotating shaft to which the star wheel and the can bottom forming unit are attached, a first drive source for rotating the rotating shaft around a central axis of the rotating shaft, and the can bottom forming unit, Reciprocating in the radial direction with respect to the bottom of the can And a pressing roller that rotates around the spindle axis and forms the concave portion extending in the circumferential direction on the annular convex portion, and a second drive source that rotates the pressing roller around the spindle axis. Features.

  The can bottom forming apparatus of the present invention includes, as a drive source such as a drive motor, a first drive source that rotates a rotating shaft to which a star wheel and a can bottom forming unit are attached, and a can bottom forming unit. And a second drive source that rotates the provided pressure roller about the spindle axis (spindle center axis) of the can bottom forming unit. That is, two drive sources are provided, and the first drive source includes a star wheel, a can held by the star wheel, and a can bottom forming unit (hereinafter referred to as a can bottom forming unit, etc.) at the center of the rotation axis. Rotate (revolve) around the axis. The second drive source rotates (revolves) the pressing roller around the can axis (spindle axis) of the can held by the star wheel.

  For this reason, for example, in order to improve production efficiency, even when the speed at which the can bottom forming unit or the like is rotated around the central axis of the rotating shaft by the first drive source is increased, the speed at which the pressing roller is rotated around the spindle axis. Can be maintained within a predetermined range by the second drive source. On the other hand, even when the rotational speed around the central axis of the rotating shaft of the can bottom forming unit or the like is lowered by the first driving source, the rotational speed around the spindle axis of the pressing roller is reduced by the second driving source. It can be maintained within a predetermined range.

  In other words, the first drive source for rotating the can bottom forming unit or the like around the central axis of the rotating shaft and the second drive source for rotating the pressing roller around the spindle axis are independent from each other. Regardless of the rotational speed around the central axis of the rotating shaft, the rotational speed around the spindle axis of the pressing roller can be maintained within the expected range. Thereby, the depth (molding amount) of the recessed part shape | molded by a can bottom is stabilized, and the pressure resistance strength of a can bottom is improved stably. Therefore, deformations such as bottom growth and buckling at the bottom of the can are reliably suppressed.

  As described above, according to the present invention, it is possible to stabilize the processing accuracy of the recess formed in the can bottom regardless of the operation speed of the apparatus (corresponding to the rotation speed around the central axis of the rotation axis of the can bottom forming unit or the like). it can. That is, regardless of the operating speed, the quality of the bottom reforming process can be stabilized and a good quality can can be manufactured.

  The can bottom forming device can switch the connection between the pressure roller and the second drive source to the connection between the pressure roller and the first drive source, and the first drive source The roller is preferably rotatable about the spindle axis.

  In the above configuration, the first drive source can be selected instead of the second drive source as the drive source for rotating the pressing roller around the spindle axis. Therefore, for example, when the frequency of changing the operation speed of the apparatus is low, the pressure roller is connected to the first drive source via an appropriate gear mechanism or the like, and the can is driven by one drive source (first drive source). Running cost can be reduced by causing rotation (revolution) around the central axis of the rotation axis of the bottom molding unit and the like and rotation (revolution) around the spindle axis of the pressing roller. Further, when the frequency of changing the operation speed of the apparatus is high, the pressure roller is connected to the second drive source, and the rotation speed around the center axis of the rotation axis of the can bottom forming unit or the like (that is, the operation speed of the apparatus). Regardless of whether the rotational speed of the pressing roller around the spindle axis is within a predetermined range by the second drive source, the above-described operational effects of the present invention can be stably obtained.

  Further, the can bottom forming device is coaxially disposed on the central axis of the rotating shaft, meshes with the driving gear which is rotatable about the central axis with respect to the rotating shaft, and is coaxial with the spindle shaft. And a driven gear connected to the pressing roller, and the rotational direction around the central axis of the rotary shaft and the rotational direction around the central axis of the drive gear are set in opposite directions to each other It is preferable.

  In this case, when the can bottom forming unit or the like is rotated in the first rotation direction (for example, clockwise) out of the center axis of the rotation shaft, the drive gear is rotated in the second rotation direction (for example in the clockwise direction) It is rotated counterclockwise. Thus, unlike the above-described configuration, for example, the above-described configuration of the present invention is compared with the rotational speed around the spindle axis of the driven gear that meshes with the drive gear when the drive gear is non-rotatably fixed to the apparatus frame or the like. Then, since the rotational speed of the driven gear meshing with the drive gear increases around the spindle axis, the rotational speed of the pressure roller connected to the driven gear around the spindle axis can be increased. Therefore, it is possible to increase the molding speed of the concave portion on the can bottom, and to improve the production efficiency.

  According to the can bottom forming apparatus of the present invention, it is possible to stabilize the processing accuracy of the recess formed in the can bottom regardless of the operation speed of the apparatus.

It is a longitudinal cross-sectional view which shows the can bottom vicinity of a can. It is sectional drawing which shows the structure of a can bottom shaping | molding apparatus. It is a figure which expands and shows the X section of FIG. It is a figure which expands and shows the Y section of FIG. It is a figure which expands and shows the Z section of FIG. It is sectional drawing which expands and shows the bottom spindle vicinity of a can bottom shaping | molding apparatus. It is sectional drawing which expands and shows the bottom spindle vicinity of a can bottom shaping | molding apparatus. It is a top view which expands and shows the bottom spindle vicinity of a can bottom shaping | molding apparatus. It is sectional drawing which expands and shows the top spindle vicinity of a can bottom shaping | molding apparatus. It is sectional drawing which expands and shows the top spindle vicinity of a can bottom shaping | molding apparatus. It is a top view which expands and shows the top spindle vicinity of a can bottom shaping | molding apparatus. It is a graph showing the relationship between the operating speed and BPR inner diameter of the Example and comparative example of this invention. It is a graph showing the relationship between the operation speed in an Example of this invention, a BPR internal diameter, and pressure | voltage resistant strength.

  Hereinafter, a can bottom forming apparatus (bottom reforming apparatus) 10 according to an embodiment of the present invention will be described with reference to the drawings. Note that the drawings used for describing the embodiments of the present invention may show enlarged, emphasized, and excerpted parts that are essential parts in order to make the features of the present invention easier to understand. The ratio is not always the same as the actual one.

First, a description will be given of the can 50 subjected to a forming process by the can bottom forming apparatus 10 of the present embodiment.
As shown in FIGS. 1 and 10 (a) and 10 (b), the can 50 includes a can body (wall) 51 that is a peripheral wall of the can and a can bottom (bottom) 52 that is a bottom wall of the can. It has a bottomed cylindrical shape. The can 50 of the present embodiment is an aluminum can made of an aluminum alloy material or the like. The inside of the can 50 is filled with contents such as a beverage, and a can lid (not shown) is wound around the open end of the can body 51. To be sealed. That is, the can 50 is a can body used for a so-called two-piece can.

The central axis of the can body 51 and the central axis of the can bottom 52 are arranged coaxially with each other. In the present embodiment, these common axes are referred to as a can axis.
The direction in which the can shaft extends (the direction along the can shaft) is referred to as the can shaft direction. Of the can axis directions, a direction from the can bottom 52 toward the opening end of the can body 51 is referred to as “upward”, and a direction from the opening end of the can body 51 toward the can bottom 52 is referred to as “downward”.
The direction orthogonal to the can axis is referred to as the radial direction. Of the radial directions, the direction approaching the can axis is referred to as the inner side in the radial direction, and the direction away from the can axis is referred to as the outer side in the radial direction.
Further, a direction around the can axis is referred to as a circumferential direction.

Various shapes such as “concave”, “convex”, “depressed”, “projecting” and the like of the can 50 used in the present embodiment are unless otherwise specified. Various shapes on the surface).
In addition, in the longitudinal sectional view (longitudinal sectional view including the can axis) of the can 50 shown in FIG. 1 and FIGS. Line shapes such as “arc”, “curve”, “straight line”, and “tangent” represent various line shapes on the outer surface of the can 50 unless otherwise specified.

  Of the can 50, the upper end of the can body 51 is an open end that opens to the outside of the can 50. The contents are filled into the can 50 through this open end. At the opening end of the can body 51, a neck portion 53 that is reduced in diameter as it goes upward is formed.

The can bottom 52 is connected to the dome portion 55 that is recessed upward in the can axis direction, and the outer peripheral edge portion of the dome portion 55, protrudes downward in the can axis direction, and extends in the circumferential direction around the can axis. And an annular convex portion (rim) 56 extending.
The annular convex portion 56 includes a grounding portion (nose portion) 59 that protrudes most downward in the can bottom 52, an inner peripheral wall (counter portion) 57 that is adjacent to the inside in the radial direction of the grounding portion 59, and a diameter of the grounding portion 59. And an outer peripheral wall (heel portion, chime portion) 58 adjacent to the outside in the direction.

In the present embodiment, a groove-shaped recess 60 that is recessed outward in the radial direction and extends along the circumferential direction is formed on the inner peripheral wall 57 of the can bottom 52 of the can 50 by the can bottom forming apparatus 10 described later. As shown in FIG. 1, in a longitudinal sectional view including the can axis of the can 50, the recess 60 has a concave curve shape.
In the present embodiment, a can (work) before the recess 60 is formed is indicated by a symbol W, and a can after the recess 60 is formed is indicated by a symbol 50.

Next, the can bottom forming apparatus 10 shown in FIGS. 2 to 11 will be described.
The can bottom forming apparatus 10 forms the concave portion 60 as shown in FIG. 1 by pressing at least one of the inner peripheral wall 57 and the outer peripheral wall 58 among the annular convex portions 56 of the can bottom 52 of the can W. . In the example of the present embodiment, a recess 60 is formed in the inner peripheral wall 57 by performing a bottom reforming process on the inner peripheral wall 57 of the annular convex portion 56.

  As shown in FIG. 2, the can bottom forming apparatus 10 includes an apparatus frame 11 that is a base of the apparatus, a rotating shaft 12 that is rotatably supported by the apparatus frame 11 via a bearing, A star wheel (turret) 13 that is attached and has a plurality of pockets for holding a work can W on the outer periphery, and a plurality of can bottoms that are attached to the rotary shaft 12 and are provided corresponding to the pockets of the star wheel 13. A first drive source 41 that rotates the molding unit 14, the star wheel 13, the can bottom molding unit 14, and the rotary shaft 12 around the central axis O of the rotary shaft 12, and a press roller 20 of the can bottom molding unit 14, which will be described later. Is rotated around the spindle axis C of the can bottom forming unit 14 (around the can axis of the can W held by the star wheel 13).

  The first drive source 41 is, for example, a drive motor or the like, and is connected to the rotary shaft 12 via a drive force transmission member such as a gear. The first drive source 41 rotates the rotating shaft 12 around the central axis O with respect to the apparatus frame 11, whereby the star wheel 13 and the plurality of can bottom forming units 14 provided integrally with the rotating shaft 12. Is rotated (revolved) around the central axis O of the rotating shaft 12.

  The star wheel 13 has a disc shape or a column shape. The central axis of the star wheel 13 is arranged coaxially with the central axis O of the rotating shaft 12. On the outer periphery of the star wheel 13, a plurality of concave curved pockets corresponding to the outer peripheral surface (convex curved surface) shape of the can body 51 of the can W are formed at equal intervals in the circumferential direction around the central axis O. Yes. In each pocket of the star wheel 13, the can body 51 of the can W is held by air suction or the like by an air suction means (not shown).

  The can bottom forming unit 14 has a spindle axis (spindle central axis) C extending so as to coincide with the can axis of the can W held by the star wheel 13. The can bottom forming unit 14 is disposed above the can W held in the pocket of the star wheel 13 in the can axis direction and is provided integrally with the rotary shaft 12, and the can W of the can W in the can axis direction. A bottom spindle 17 that is disposed below and provided integrally with the rotary shaft 12. The top spindle 15 and the bottom spindle 17 are opposed to each other with a pocket of the star wheel 13 and a can W held in the pocket sandwiched therebetween and spaced apart from each other in the direction of the spindle axis C which is a common axis.

  The top spindle 15 has a top support member 16 that supports the open end of the can body 51 of the can W held in the pocket of the star wheel 13. The bottom spindle 17 reciprocates in the radial direction with respect to the bottom support member 18 that supports the bottom 52 of the can W held in the pocket of the star wheel 13 and rotates around the spindle axis C. And the pressing roller 20 that forms the concave portion 60 extending in the circumferential direction on the annular convex portion 56.

  The spindle axis C of the top spindle 15 and the center axis of the top support member 16, and the spindle axis C of the bottom spindle 17 and the center axis of the bottom support member 18 are the can axis of the can W held in each pocket of the star wheel 13. Are arranged coaxially. Each spindle axis C corresponding to each pocket of the star wheel 13 extends parallel to the central axis O of the rotating shaft 12.

  As shown in FIGS. 4 and 10 (a) and 10 (b), the top support member 16 has a top tube shape, and includes a peripheral wall and a top wall. The top support member 16 is in contact with the upper end (opening end) of the can body 51 of the can W and can support the open end of the can body 51. Specifically, the neck portion 53 of the can body 51 comes into contact with the peripheral wall of the top support member 16. In the illustrated example, a guide member is fitted in the open end of the can body 51, and the can body 51 is also supported from the inside in the radial direction. Note that, instead of bringing the neck portion 53 of the can body 51 into contact with the peripheral wall of the top support member 16 as described above, the upper end opening edge of the can body 51 is brought into contact with the top wall of the top support member 16. May be.

  As shown in FIGS. 4 and 7A and 7B, the bottom support member 18 has a bottomed cylindrical shape and includes a peripheral wall and a bottom wall. The bottom support member 18 can abut the can bottom 52 of the can W and the lower end of the can body 51 to support the vicinity of the can bottom 52. Specifically, the lower end portion of the can body 51 is fitted in the peripheral wall of the bottom support member 18. Further, the grounding portion 59 and the outer peripheral wall 58 of the can bottom 52 abut on the bottom wall of the bottom support member 18.

  As shown in FIGS. 2, 3, 6 (a), 6 (b) and FIG. 8, the bottom spindle 17 includes a bottom cam follower 19. The bottom cam follower 19 is engaged with a bottom cam 27 provided integrally with the apparatus frame 11. In the example of this embodiment, the bottom cam 27 is a cylindrical cam that is disposed on the radially outer side of the rotary shaft 12 and extends around the central axis O of the rotary shaft 12.

  That is, the can bottom forming apparatus 10 includes a bottom cam mechanism 28 including a bottom cam follower 19 and a bottom cam 27 that engages with the bottom cam follower 19. The bottom cam mechanism 28 reciprocates the bottom support member 18 with respect to the can W in the direction of the can axis (spindle axis C).

  Specifically, the bottom cam 27 of the bottom cam mechanism 28 forms a predetermined track whose position along the direction of the central axis O changes as it goes around the central axis O of the rotating shaft 12. By guiding the bottom cam follower 19 along this track, the bottom cam follower 19 reciprocates within a predetermined stroke L1 along the spindle axis C direction. Further, the bottom support member 18 coupled to the bottom cam follower 19 also reciprocates within a predetermined stroke L1 along the spindle axis C direction.

  As shown in FIGS. 2, 4, and 7 (a) and 7 (b), the bottom spindle 17 approaches and separates radially from the annular convex portion 56 of the can bottom 52, and the inner peripheral wall 57. And a pressing roller 20 that presses at least one of the outer peripheral wall 58 to form the recess 60. In the present embodiment, the pressing roller 20 can reciprocate in the radial direction with respect to the inner peripheral wall 57 of the can bottom 52, and the inner peripheral wall 57 is pressed from the inner side to the outer side in the radial direction. By rolling along the circumferential direction around the can axis, a groove-like recess 60 extending in the circumferential direction is formed in the inner circumferential wall 57. That is, the pressing roller 20 rotates around the central axis of the pressing roller 20 while revolving around the can axis (spindle axis C) while being pressed by the inner peripheral wall 57 of the can bottom 52.

  The pressing roller 20 is a molding die made of, for example, a cemented carbide. The pressing roller 20 has a disc shape, a cylindrical shape, or a columnar shape, and its central axis extends in parallel with the spindle axis C. The pressing roller 20 is provided in the bottom support member 18 of the bottom spindle 17 so as to be rotatable around its central axis and slidable in a radial direction perpendicular to the central axis.

The bottom spindle 17 is provided with a link mechanism including a link portion 22 for sliding the pressing roller 20 in the radial direction. The pressing roller 20 is connected to the forming cam follower 21 via a link portion 22 or the like.
As shown in FIGS. 3, 6 (a), and 6 (b), the molding cam follower 21 is engaged with a molding cam 29 provided integrally with the apparatus frame 11. In the example of the present embodiment, the forming cam 29 is a cylindrical cam that is disposed on the radially outer side of the rotary shaft 12 and extends around the central axis O of the rotary shaft 12.

  That is, the can bottom molding apparatus 10 includes a molding cam mechanism 30 including a molding cam follower 21 and a molding cam 29 that engages with the molding cam follower 21. The molding cam mechanism 30 reciprocates the pressing roller 20 in the radial direction perpendicular to the can axis (spindle axis C) with respect to the can W. In the illustrated example, the bottom cam 27 and the molding cam 29 are integrally formed on one cylindrical member.

Specifically, the molding cam 29 of the molding cam mechanism 30 forms a predetermined track whose position along the direction of the central axis O changes as it goes around the central axis O of the rotary shaft 12. By guiding the molding cam follower 21 along this track, the molding cam follower 21 reciprocates along the spindle axis C in a range of a predetermined stroke L2 larger than the stroke L1. The pressing roller 20 reciprocates within the range of the predetermined stroke L1 along the spindle axis C direction, and the difference between the stroke L2 and the stroke L1 (L2−L1) by the action of the link portion 22 or the like (link mechanism). ), The linear motion in the direction of the spindle axis C reciprocates in the radial direction within the range of the stroke converted into the sliding movement in the radial direction perpendicular to the spindle axis C.
Thereby, the pressing roller 20 can press the inner peripheral wall 57 of the annular convex portion 56 of the can bottom 52 held by the bottom support member 18 from the radial direction.

  As shown in FIGS. 2, 3, and 6 (a) and 6 (b), the can bottom forming apparatus 10 is disposed coaxially with the central axis O of the rotating shaft 12, and the central axis O with respect to the rotating shaft 12. A drive gear 23 that can rotate around, and a driven gear 24 that meshes with the drive gear 23 and is coaxially disposed on the spindle shaft C (can shaft of the can W held by the star wheel 13) and connected to the pressing roller 20. It is equipped with.

The drive gear 23 has a circular ring shape or a cylindrical shape, and the rotating shaft 12 is inserted through the drive gear 23. The drive gear 23 is rotatably mounted around the central axis O on the radially outer side of the rotary shaft 12 through a bearing provided on the outer periphery of the rotary shaft 12.
The driven gears 24 are provided on the respective bottom spindles 17, and all the driven gears 24 are meshed with one drive gear 23. That is, the driven gear 24 is a planetary gear that is arranged on the outer periphery of the drive gear 23 that is a sun gear at equal intervals, and rotates while revolving around the drive gear 23.

In FIG. 2, the second drive source 42 is, for example, a drive motor or the like, and is connected to the drive gear 23 via a drive force transmission member such as a pulley, a belt, a sprocket, and a gear.
In the example shown in FIG. 2, a connection gear 44 is provided which is integrated with the drive gear 23 and is rotatable about the central axis O around the rotary shaft 12. In detail, the drive gear 23 is arrange | positioned at the 1st edge part (one edge part) along the central-axis O direction of the cylindrical body in which the rotating shaft 12 was penetrated inside, and the 2nd edge part (other edge) The connecting gear 44 is arranged at the center part, and these are integrated with the central axis O as a common axis (that is, coaxially).

Further, between the connection gear 44 and the second drive source 42, a connection gear 45 meshing with the connection gear 44, a sprocket 47 integrated with the connection gear 45 via the shaft 46, the sprocket 47 and the second drive source 42. And a sprocket 48 provided between the drive source 42 (also between the sprocket 47 and the first drive source 41 as will be described later). The shaft 46 is supported by a bearing (not shown) of the apparatus frame 11, and a first end (one end; an end located inside the apparatus frame 11) along the central axis direction of the shaft 46. ) And a sprocket 47 is disposed at the second end (the other end, the end located outside the apparatus frame 11).
The rotational driving force of the second drive source 42 is transmitted to the drive gear 23 via the sprocket 48, sprocket 47, shaft 46, connection gear 45 and connection gear 44.

  When the drive gear 23 is rotated around the central axis O with respect to the apparatus frame 11 by the second drive source 42, the driven gear 24 meshing with the drive gear 23 is driven relative to the drive gear 23. It rotates around the spindle axis C while revolving around the outer periphery of the gear 23. Further, when the driven gear 24 is rotated around the spindle axis C, the pressing roller 20 connected to the driven gear 24 causes the bottom support member 18 that supports the can W held by the star wheel 13 and the can bottom 52 thereof. Rotate (revolve) around the spindle axis C.

  In the present embodiment, the rotation direction around the central axis O of the rotary shaft 12 with respect to the apparatus frame 11 and the rotation direction around the central axis O of the drive gear 23 with respect to the apparatus frame 11 are set in opposite directions. That is, the rotational direction of the rotary shaft 12 that is driven to rotate about the central axis O by the first drive source 41 and the rotational direction of the drive gear 23 that is driven to rotate about the central axis O by the second drive source 42 are mutually. The opposite is the case.

  Further, in this embodiment, the connection between the pressure roller 20 and the second drive source 42 can be switched to the connection between the pressure roller 20 and the first drive source 41, and the first drive source 41 causes the pressure roller 20 to be connected to the spindle. It can rotate around the axis C. Specifically, the can bottom forming apparatus 10 is provided with a shaft-like connecting member 43 capable of connecting the first drive source 41 and the drive gear 23. The rotational driving force of the first drive source 41 is transmitted to the drive gear 23 via the connection member 43, the sprocket 48, the sprocket 47, the shaft 46, the connection gear 45 and the connection gear 44.

As described above, when the second driving source 42 and the driving gear 23 are connected and the driving force of the second driving source 42 is transmitted to the pressing roller 20, the connecting member 43 is removed, for example. The connection state between the first drive source 41 and the drive gear 23 via the member 43 is released.
Further, when the first drive source 41 and the drive gear 23 are connected and the driving force of the first drive source 41 is transmitted to the pressing roller 20, the first drive source 41 is driven via the connecting member 43. The connection state between the second drive source 42 and the drive gear 23 is released by connecting the gear 23 and removing the belt member that connects the motor pulley of the second drive source 42 and the sprocket 48, for example.

  As shown in FIGS. 2, 5, 9 (a), 9 (b) and FIG. 11, the top spindle 15 includes a top cam follower 25. The top cam follower 25 is engaged with a top cam 31 provided integrally with the apparatus frame 11. In the example of the present embodiment, the top cam 31 is a cylindrical cam that is disposed on the outer side in the radial direction of the rotary shaft 12 and extends around the central axis O of the rotary shaft 12.

  That is, the can bottom forming apparatus 10 includes a top cam mechanism 32 including a top cam follower 25 and a top cam 31 engaged with the top cam follower 25. Then, the top cam mechanism 32 reciprocates the top support member 16 with respect to the can W in the direction of the can axis (spindle axis C).

Specifically, the top cam 31 of the top cam mechanism 32 forms a predetermined track whose position along the direction of the central axis O changes as it goes around the central axis O of the rotary shaft 12. As the top cam follower 25 is guided along this track, the top spindle 15 reciprocates within a predetermined stroke L3 along the spindle axis C direction. However, the top support member 16 of the top spindle 15 is brought into contact with the opening end of the can body 51 of the can W in the middle of the stroke L3, and after the contact, the action of the elastic member 26 (contraction due to elastic deformation). Thus, further forward movement toward the can W is stopped. For this reason, the stroke L4 of the top support member 16 shown in FIG.4 and FIG.10 (a), (b) is set smaller than the said stroke L3.
That is, in FIGS. 4 and 10A and 10B, the top spindle 15 includes the elastic member 26, and the elastic member 26 faces the top support member 16 toward the can W in the direction of the can axis (spindle axis C). Energize to.

Next, an example of operation | movement of the can bottom shaping | molding apparatus 10 is demonstrated.
The rotary shaft 12 is rotated around the central axis O by the rotational driving force transmitted from the first drive source 41. Along with this, the star wheel 13 and the can bottom forming unit 14 attached to the rotary shaft 12 are also rotated (revolved) around the central axis O.
Accordingly, the bottom spindle 17 and the bottom support member 18 are moved by the action of the bottom cam 27 and the molding cam 29 of the apparatus frame 11 and the bottom cam follower 19 and the molding cam follower 21 engaged therewith. It moves forward (approaching) in the direction of the spindle axis C toward the can W held in the pocket of the star wheel 13. That is, the bottom spindle 17 moves along the spindle axis C direction by the stroke L1 toward the top spindle 15 (upward in the can axis direction, the same applies hereinafter). Accordingly, the bottom support member 18 is brought into contact with the can bottom 52 of the can W.

  Specifically, the bottom wall of the bottom support member 18 abuts against the ground contact portion 59 and the outer peripheral wall 58 of the can bottom 52 of the can W from the spindle axis C direction, and the lower end portion of the can body 51 is the bottom support member. It fits in 18 peripheral walls. Further, the pressing roller 20 provided in the bottom support member 18 is in a state of being disposed close to the can bottom 52 of the can W. Specifically, the outer peripheral edge portion (saddle portion) of the pressing roller 20 is disposed to face the inner peripheral wall 57 of the annular convex portion 56 of the can bottom 52 from the inside in the radial direction.

  Further, the top spindle 15 and the top support member 16 are moved toward the can W held in the pocket of the star wheel 13 by the action of the top cam 31 of the apparatus frame 11 and the top cam follower 25 engaged therewith. Move forward (approach) in the direction of axis C. That is, the top spindle 15 moves by the stroke L3 along the spindle axis C direction toward the bottom spindle 17 (downward in the can axis direction, the same applies hereinafter). Thereby, the top support member 16 is brought into contact with the opening end portion of the can body 51 of the can W.

Specifically, in the middle of the stroke L3, the neck portion 53 at the opening end of the can body 51 comes into contact with the peripheral wall of the top support member 16. After the top support member 16 abuts on the opening end of the can body 51 in this way, the elastic member 26 is elastically deformed according to the amount of forward movement of the top spindle 15 thereafter, so that the top support member 16 Further forward movement toward the bottom spindle 17 along the spindle axis C direction is stopped. As a result, the top support member 16 moves toward the bottom spindle 17 side along the spindle axis C direction by a stroke L4 that is smaller than the stroke L3.
In the present embodiment, the bottom support member 18 is brought into contact with the can bottom 52 and the top support member 16 is brought into contact with the opening end of the can body 51 at substantially the same time. is there.

  As shown in FIG. 4 and the like, the can W is sandwiched between the bottom support member 18 and the top support member 16 from both sides in the spindle axis C direction. At this time, the can W is supported by the support members 16 and 18 while being pressurized in the can axis direction (spindle axis C direction) by the restoring deformation force of the elastic member 26.

  Next, the molding cam follower 21 moves forward toward the top spindle 15 along the spindle axis C direction according to the difference (L2−L1) between the stroke L2 and the stroke L1. At this time, the link portion 22 (link mechanism) connected to the forming cam follower 21 causes the linear movement of the forming cam follower 21 in the direction of the spindle axis C to slide in the radial direction perpendicular to the spindle axis C. Convert to As a result, the pressure roller 20 connected to the link portion 22 is moved outward in the radial direction, and the outer peripheral edge portion (the flange portion) of the pressure roller 20 is the inner peripheral wall 57 of the annular convex portion 56 of the can bottom 52. To press the inner peripheral wall 57.

  Further, the driving gear 23 is rotated around the central axis O by the rotational driving force transmitted from the second driving source 42 (or the rotational driving force transmitted from the first driving source 41 via the connecting member 43). A driven gear 24 meshing with the drive gear 23 is rotated around the spindle axis C. Accordingly, the link portion 22 and the pressing roller 20 connected to the driven gear 24 rotate (revolve) around the spindle axis C. As a result, the pressing roller 20 rolls on the inner peripheral wall 57 of the annular protrusion 56 around the can axis (rotates while revolving), and the inner peripheral wall 57 is a ring-shaped groove extending along the circumferential direction. A recess 60 is formed.

  From this point onward, the pressing roller 20 first retracts from the inner peripheral wall 57 toward the inside in the radial direction in the reverse procedure. Further, the top spindle 15 and the bottom spindle 17 move backward (separate) in the spindle axis C direction with respect to the can W, and the support state of the can W by the top support member 16 and the bottom support member 18 is released.

  In this way, the bottom reforming process is performed on the can bottom 52 of the can W by the can bottom forming apparatus 10, and the recess 60 is formed in the can bottom 52. The can 50 in which the recess 60 is formed is transferred to a subsequent process of the can bottom forming apparatus 10.

  The can bottom forming apparatus 10 of the present embodiment described above is a first drive that rotates the rotating shaft 12 to which the star wheel 13 and the can bottom forming unit 14 are attached as a drive source such as a drive motor around the central axis O. A source 41 and a second drive source 42 for rotating the pressing roller 20 provided in the can bottom forming unit 14 around the spindle axis C of the can bottom forming unit 14 are provided. That is, two drive sources are provided, of which the first drive source 41 includes the star wheel 13, the can W held by the star wheel 13, and the can bottom forming unit 14 (hereinafter referred to as the can bottom forming unit 14 or the like). Is rotated (revolved) around the central axis O of the rotating shaft 12. The second drive source 42 rotates (revolves) the pressing roller 20 around the can axis of the can W held by the star wheel 13 (around the spindle axis C).

  Therefore, for example, for the purpose of improving the production efficiency, even when the first drive source 41 increases the speed at which the can bottom forming unit 14 and the like are rotated around the central axis O of the rotary shaft 12, the pressing roller 20 is moved to the spindle axis C. The rotation speed can be maintained within a predetermined range by the second drive source 42. On the contrary, even when the first drive source 41 reduces the rotational speed around the central axis O of the rotary shaft 12 such as the can bottom forming unit 14, the spindle of the pressure roller 20 is driven by the second drive source 42. The rotational speed around the axis C can be maintained within a predetermined range.

  That is, the first drive source 41 that rotates the can bottom forming unit 14 and the like around the central axis O of the rotary shaft 12 and the second drive source 42 that rotates the pressing roller 20 around the spindle axis C are independent of each other. Therefore, regardless of the rotational speed around the central axis O of the rotary shaft 12 such as the can bottom forming unit 14, the rotational speed around the spindle axis C of the pressing roller 20 can be maintained within the expected range. Thereby, the depth (molding amount) of the recess 60 formed in the can bottom 52 is stabilized, and the pressure strength of the can bottom 52 is stably increased. Therefore, deformation such as bottom growth and buckling in the can bottom 52 is reliably suppressed.

  As described above, according to the present embodiment, the processing of the recess 60 formed in the can bottom 52 regardless of the operation speed of the apparatus (corresponding to the rotation speed around the central axis O of the rotation shaft 12 of the can bottom forming unit 14 or the like). Accuracy can be stabilized. That is, regardless of the operating speed, the quality of the bottom reforming process can be stabilized, and a good quality can 50 having a stable quality can be manufactured.

In the present embodiment, by using the connecting member 43, the connection between the pressing roller 20 and the second drive source 42 can be switched to the connection between the pressing roller 20 and the first drive source 41, and the first drive is performed. Since the source 41 can rotate the pressing roller 20 around the spindle axis C, the following effects can be obtained.
That is, in the above configuration, the first drive source 41 can be selected in place of the second drive source 42 as the drive source for rotating the pressing roller 20 around the spindle axis C. Therefore, for example, when the frequency of changing the operating speed of the apparatus is low, the pressing roller 20 is connected to the first driving source 41 via the connecting member 43 and an appropriate gear mechanism, etc. 1 drive source 41) reduces the running cost by rotating around the central axis O of the rotary shaft 12 such as the can bottom forming unit 14 (revolution) and rotating around the spindle axis C of the pressing roller 20 (revolution). it can. In addition, when the frequency of changing the operation speed of the apparatus is high, the pressure roller 20 is connected to the second drive source 42 and the rotation speed around the central axis O of the rotation shaft 12 of the can bottom forming unit 14 or the like ( In other words, regardless of the operation speed of the apparatus, the operational effect of the above-described embodiment can be stably obtained by keeping the rotational speed of the pressing roller 20 around the spindle axis C within the predetermined range by the second drive source 42. it can.

In this embodiment, the rotation direction around the central axis O of the rotary shaft 12 that rotates (revolves) the can bottom forming unit 14 and the like around the central axis O and the press roller 20 rotates (revolves) around the spindle axis C. Since the rotation directions of the drive gear 23 around the central axis O are set in opposite directions, the following effects are obtained.
That is, in this case, when the can bottom forming unit 14 or the like is rotated in the first rotation direction (for example, clockwise) around the central axis O of the rotary shaft 12, the drive gear 23 is the first around the central axis O. 2 in the direction of rotation (for example, counterclockwise). Thereby, unlike this embodiment, for example, when the drive gear 23 is fixed to the apparatus frame 11 so as not to rotate, the rotational speed of the driven gear 24 meshing with the drive gear 23 around the spindle axis C is In this embodiment, the rotational speed around the spindle axis C of the driven gear 24 that meshes with the drive gear 23 increases, so that the rotational speed around the spindle axis C of the pressing roller 20 connected to the driven gear 24 can be increased. Therefore, the molding speed of the recess 60 in the can bottom 52 can be increased, and the production efficiency can be improved.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention, for example, as described below.

  In the above-described embodiment, the pressing roller 20 presses the inner peripheral wall 57 of the annular convex portion 56 of the can bottom 52, and the groove-shaped concave portion extends along the circumferential direction while being recessed radially outward in the inner peripheral wall 57. Although 60 was formed and the bottom reforming process was performed, it is not limited to this. For example, the pressing roller 20 presses the outer peripheral wall 58 of the annular convex portion 56 of the can bottom 52 to form a groove-shaped concave portion 60 that is recessed inward in the radial direction and extends along the circumferential direction. A bottom reforming process may be performed. Alternatively, the pressing roller 20 may be pressed against both the inner peripheral wall 57 and the outer peripheral wall 58 of the annular convex portion 56 of the can bottom 52 to form the concave portions 60 on the inner peripheral wall 57 and the outer peripheral wall 58, respectively.

  Moreover, in the above-mentioned embodiment, although the can bottom shaping | molding apparatus 10 shape | molded the recessed part 60 with respect to the can bottom 52 of the can W used for the can main body of a 2 piece can, it is limited to this. It is not something. The can bottom forming apparatus 10 is for forming a recess 60 on the can bottom of a bottle can that has been necked or threaded at the opening end of the can body by, for example, a bottle necker (bottle can manufacturing apparatus). There may be. Or you may shape | mold the recessed part 60 with respect to the can bottom of DI (Drawing & Ironing) can produced in the manufacture process of a bottle can. The DI can is a can body in which the neck portion 53 is not formed at the opening end of the can body 51 of the can W described in the above-described embodiment (that is, the outer diameter of the can body 51 is different from that of the can bottom 52. A can body made constant from the connection portion to the opening end).

  In addition, in the range which does not deviate from the meaning of this invention, you may combine each structure (component) demonstrated by the above-mentioned embodiment, a modification, and a remark etc., addition of a structure, omission, substitution, others It can be changed. Further, the present invention is not limited by the above-described embodiments, and is limited only by the scope of the claims.

  Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to this embodiment.

[Confirmation test of BPR inner diameter by operating speed]
The operating speed of the can bottom forming apparatus 10 (corresponding to the rotating speed around the central axis O of the rotating shaft 12 of the can bottom forming unit 14 etc.) and the BPR inner diameter (inner peripheral wall 57 of the can bottom 52 of the can 50 subjected to the bottom reforming process. A confirmation test was conducted on the relationship between the maximum diameter of the ring-shaped convex portion 56, that is, the maximum inner diameter of the annular convex portion 56 in the concave portion 60).

  A plurality of operating speeds of the apparatus were set between 800 and 1800 cpm. “Cpm” represents the number of cans produced per minute (number of cans for bottom reforming) of the apparatus. Specifically, for example, when the number of pockets of the star wheel 13 is 12, the driving speed when the star wheel 13 rotates 100 times per minute is 1200 cpm.

  In the embodiment of the present invention, the first driving source 41 and the second driving source 42 are used as driving sources, and the first driving source 41 rotates (revolutions) around the central axis O of the rotating shaft 12 of the can bottom forming unit 14 or the like. And the second driving source 42 rotates (revolves) the pressing roller 20 around the spindle axis C. Then, according to the magnitude of the rotational speed around the central axis O of the rotary shaft 12 of the can bottom forming unit 14 or the like (operation speed of the apparatus: cpm), the rotational speed around the spindle axis C of the pressing roller 20 with respect to the rotational speed. The ratio (speed ratio:%) was changed.

Specifically, as shown in Table 1 to be described later, when the rotational speed (operation speed; hereinafter referred to as the first rotational speed) around the central axis O of the rotary shaft 12 of the can bottom forming unit 14 or the like is 1200 cpm. The speed ratio of the rotation speed of the pressing roller 20 around the spindle axis C (hereinafter referred to as the second rotation speed) to the first rotation speed was 100% (reference value). When the first rotational speed is reduced below 1200 cpm, the speed ratio of the second rotational speed is increased more than 100%, and when the first rotational speed is increased above 1200 cpm, The speed ratio of the second rotation speed was reduced to less than 100% so that the (actual) second rotation speed of the pressing roller 20 was within a predetermined range.
More specifically, each of the first drive source 41 and the second drive source 42 is a drive motor, and the motor rotation speed of the second drive source 42 with respect to the motor rotation speed of the first drive source 41 (the frequency of the motor power supply). The ratio of the motor power frequency) was the above ratio (speed ratio).

  On the other hand, in the comparative example, only the first drive source 41 is used as the drive source, and the first drive source 41 rotates (revolves) around the central axis O of the rotary shaft 12 such as the can bottom forming unit 14 and the pressure roller 20. Rotation around the spindle axis C (revolution). For this reason, the ratio (speed ratio:%) of the second rotation speed of the pressing roller 20 to the first rotation speed (operating speed: cpm) of the can bottom forming unit 14 or the like is the same as that of the can bottom forming unit 14 or the like. It is constant regardless of the magnitude of the first rotation speed.

  Specifically, as shown in Table 2 to be described later, the second rotational speed relative to the first rotational speed over the entire first rotational speed (operating speed) 800 to 1800 cpm of the can bottom forming unit 14 or the like. The speed ratio was fixed at 120%. That is, in the comparative example, the reduction ratio is made constant by a gear mechanism or the like interposed between the first drive source 41 and the pressing roller 20. For this reason, if the first rotation speed of the can bottom forming unit 14 or the like increases, the second rotation speed of the pressing roller 20 also increases in proportion thereto. Further, if the first rotation speed of the can bottom forming unit 14 or the like decreases, the second rotation speed of the pressing roller 20 also decreases in proportion thereto. The reason why the speed ratio is set to 120% is to maintain the pressure resistance strength of the can bottom 52 after BPR processing by securing the molding amount (depth) of the recess 60 even at the minimum operation speed of 800 cpm.

And in each of the Example and comparative example of this invention, the BPR internal diameter after carrying out the bottom reform process to the can bottom 52 and shape | molding the recessed part 60 was measured. At each operating speed, measurement of the BPR inner diameter was carried out by arbitrarily sampling 20 cans, and the average value, maximum value, minimum value, standard deviation (σ) and 3σ were confirmed.
The confirmation result of the Example of this invention is shown in Table 1, and the confirmation result of the comparative example is shown in Table 2. FIG. 12 shows the relationship between the operation speed and the BPR inner diameter.

From the results of Table 1 and FIG. 12, in the embodiment of the present invention, the BPR inner diameter of the can bottom 52 is made substantially constant regardless of the operation speed of the apparatus (the first rotation speed of the can bottom forming unit 14 and the like). Thus, it was confirmed that the variation in the BPR inner diameter was remarkably suppressed. That is, it has been found that the molding amount (depth) of the recess 60 formed in the can bottom 52 is constant regardless of the operation speed.
On the other hand, from the results of Table 2 and FIG. 12, it was found that in the comparative example, the BPR inner diameter of the can bottom 52 varies greatly depending on the operation speed of the apparatus. Specifically, for example, when the operation speed is 800 cpm and the operation speed is 1800 cpm, the BPR inner diameter is changed by about 0.3 mm.

[Confirmation test of BPR inner diameter and pressure strength by operating speed]
Next, using the examples of the present invention, a confirmation test was performed on the relationship between the operation speed, the BPR inner diameter, the pressure strength, and the like. Specifically, the bottom reforming process is performed on the can bottom 52 at each of the operation speeds of 800 cpm, 1300 cpm, and 1800 cpm under the same conditions as those of the embodiment of the present invention in the “BPR inner diameter confirmation test using the operation speed” described above. The BPR inner diameter, the bottom depth (dome portion depth), the pressure resistance and the bottom growth (can bottom elongation deformation amount) after forming the recess 60 were measured. The number of cans for each operating speed was 20 cans arbitrarily extracted, and the internal pressure at the time of bottom growth measurement was 618 kPa.
The confirmation results are shown in Tables 3 to 5 and FIG.

  From the results of Tables 3 to 5 and FIG. 13, it was found that the BPR inner diameter, the bottom depth, the pressure strength, and the bottom growth are substantially constant at each operation speed in the examples of the present invention. In other words, regardless of the operating speed of the apparatus, the processing accuracy of the recess 60 formed in the can bottom 52 can be stabilized, and a non-defective can 50 having a stable quality with no variation in the pressure strength of the can bottom 52 is manufactured. It was confirmed that it was possible.

  According to the can bottom forming apparatus of the present invention, it is possible to stabilize the processing accuracy of the recess formed in the can bottom regardless of the operation speed of the apparatus. Therefore, it has industrial applicability.

10 Can bottom molding equipment (bottom reforming equipment)
12 Rotating shaft 13 Star wheel (turret)
14 can bottom forming unit 16 top support member 18 bottom support member 20 pressure roller 23 drive gear 24 driven gear 41 first drive source 42 second drive source 43 connecting member 50 can 51 can body 52 can bottom 55 dome portion 56 annular convex portion (rim)
57 Inner wall (counter part)
58 Perimeter wall (heel, chime)
60 Concave part C Spindle shaft (can shaft)
O Center axis W Can (work)

Claims (3)

In the can bottom of a can having a can body and a can bottom and having a bottomed cylindrical shape,
A dome portion recessed upward in the can axis direction;
Continuing to the outer peripheral edge of the dome, and projecting downward in the can axis direction, an annular convex portion extending around the can axis is formed,
A can bottom forming device for forming a recess by pressing at least one of an inner peripheral wall and an outer peripheral wall of the annular convex part,
A star wheel for holding the can body of the can;
A can bottom forming unit having a spindle axis extending to coincide with the can axis of the can held by the star wheel;
A rotating shaft to which the star wheel and the can bottom forming unit are attached;
A first drive source for rotating the rotating shaft around a central axis of the rotating shaft;
A pressure roller, which is included in the can bottom forming unit, reciprocates in the radial direction with respect to the can bottom of the can and rotates around the spindle axis to form the concave portion extending in the circumferential direction on the annular convex portion. When,
A can bottom forming apparatus comprising: a second drive source that rotates the pressing roller about the spindle axis. The can bottom forming apparatus according to claim 1,
The connection between the pressure roller and the second drive source can be switched to the connection between the pressure roller and the first drive source, and the first drive source can rotate the pressure roller around the spindle axis. Can bottom molding equipment. It is a can bottom molding device according to claim 1 or 2,
A drive gear disposed coaxially with the central axis of the rotary shaft and rotatable about the central axis with respect to the rotary shaft;
A driven gear meshing with the drive gear, coaxially disposed on the spindle shaft and connected to the pressing roller,
A can bottom forming apparatus in which a rotation direction around a center axis of the rotation shaft and a rotation direction around a center axis of the drive gear are set in opposite directions.

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