JP3758571B2 - Bottle can manufacturing method and bottle can manufacturing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bottle can manufacturing method and a bottle can manufacturing apparatus for forming an opening of a bottle can to which a cap is attached.
[0002]
[Prior art]
A so-called bottle can obtained by drawing a bottomed cylindrical can body made of an aluminum material has a screw portion 1 shown in FIG. 7A on the outer periphery of the opening serving as the upper end of the bottle neck portion. A cap 3 shown in FIG. 7B is attached to the screw portion 1 after the product is filled in the bottle can. As shown in FIG. 7C, the cap 3 includes a cap body 7 in which a cap screw portion 5 is formed following the screw portion 1 of the bottle can, and a breaking portion (so-called bridge) 9 at a lower end of the cap body 7. It consists of the opening peripheral part (what is called a skirt) 11 provided continuously through.
[0003]
The breaking portion 9 of the cap 3 is formed by alternately arranging a plurality of minute slits 13 and connecting portions 15 in the circumferential direction, and is caused by a moment in the relative rotational direction acting on the cap body 7 and the opening peripheral edge portion 11. The connecting portion 15 is broken so that the cap 3 can be separated into a cap body 7 that is detached from the bottle can and an opening peripheral portion 11 that is left in the neck portion. As shown in FIG. 7B, the cap 3 is attached to the lower surface side of the bulging portion 17 formed below the threaded portion 1 of the bottle can neck by bending the end of the opening peripheral edge portion 11.
[0004]
Conventionally, a bottle can having such a screw portion 1 and a bulging portion 17 has an opening of a bottomed cylindrical can body 19 made of an aluminum material as shown in FIG. As shown in FIG. 8 (b), once the diameter is reduced, the diameter is increased again by a predetermined distance h from the opening end as shown in FIG. 8 (c), and further from the opening end as shown in FIG. 8 (d). The threaded portion 1 and the bulged portion 17 are formed by leaving the expanded portion where the threaded portion 1 is not formed as the bulged portion 17 by forming the threaded portion 1 at a constant distance n.
[0005]
[Problems to be solved by the invention]
However, in the above-described conventional method for manufacturing a bottle can, the neck portion once reduced in diameter is enlarged, and the screw portion 1 is formed at a constant distance n from the opening portion of the enlarged diameter portion, and the screw portion 1 is not formed. Since the enlarged diameter portion is the bulging portion 17, there is a problem in that the formation position and shape of the bulging portion vary due to the diameter expansion processing, screw formation processing, or material anisotropy. For example, when the height h of the bulging portion 17 shown in FIG. 9 is increased and the edge of the opening of the cap is bent, an excessive force is applied to the bridge, causing a bridge break. Further, when the lower surface angle θ of the bulging portion 17 is reduced, buckling is likely to occur when the opening peripheral portion is bent, whereas when the angle θ is increased, the opening peripheral portion rotates with the cap body when the cap is opened, It became difficult to break the bridge. Further, when the angle θ is increased, the holding force with respect to the bulging portion of the cap becomes weak, and when the internal pressure of the can is high, the cap is pushed upward in the axial direction, which may impair the sealing performance. These defects are prominent even when the cross-sectional shapes at different positions in the circumferential direction of the bulging part are not uniform as shown in FIG.
The present invention has been made in view of the above situation, and a bottle can manufacturing method and a bottle can capable of forming a bulging portion having a uniform cross-sectional shape at an arbitrary position in the circumferential direction at a predetermined position. An object of the present invention is to provide a manufacturing apparatus, and to prevent the cap from being broken, buckled, rotated, and sealed.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, the bottle can manufacturing method according to the present invention is such that the diameter of the opening of the bottomed cylindrical can body is once reduced, and then a predetermined distance is increased again from the opening end. Further, in the method of manufacturing a bottle can, in which a screw is formed at a certain distance from the opening end to leave a diameter-expanded portion where the screw is not formed as a bulging portion, after the screw is formed, re-forming having a predetermined outer peripheral shape A roller is rolled on the outer peripheral surface of the bulging portion to reshape the bulging portion.
[0007]
In this bottle can manufacturing method, a re-forming roller having a predetermined outer peripheral shape is rolled on the outer peripheral surface of the bulging portion to re-mold the bulging portion, so that the cross-sectional shape at an arbitrary position in the circumferential direction is uniform. It is possible to form a bulging portion at a predetermined position, which makes it possible to uniformly wind the periphery of the opening of the cap around the bulging portion with a desired bending amount and bending angle, and the bridge breaks. The buckling of the bent part, the circumference of the cap, and the sealing performance are not reduced.
[0008]
The method for manufacturing a bottle can according to claim 2 is the method for manufacturing a bottle can according to claim 1, wherein when the diameter is increased from the opening end by a predetermined distance, a remolding allowance is expected from a position where the bulging portion is formed. The diameter is expanded to a position where the predetermined distance is extended.
[0009]
In this bottle can manufacturing method, when a predetermined distance is expanded from the opening end, the diameter is expanded to a position where the predetermined distance is extended by an amount corresponding to the remolding allowance from the formation position of the bulging portion. As a result, even if the shape and position of the expanded diameter portion varies due to the accuracy of diameter expansion processing and screw forming processing, or the anisotropy of the material, and the bulging portion becomes shallower than the predetermined value, The margin can be crushed by the re-forming roller, and the bulging portion can be re-formed at a predetermined position.
[0010]
The method for manufacturing a bottle can according to claim 3 is the method for manufacturing a bottle can according to claim 1 or 2, wherein three or more re-forming rollers are simultaneously pressed at equal intervals in the circumferential direction to perform re-forming. It is characterized by that.
[0011]
In this bottle can manufacturing method, the bulging portion is simultaneously pressed against three or more re-forming rollers to prevent misalignment between the center of the bulging portion and the center of the re-forming roller arrangement circle. The part is reshaped with high roundness.
[0012]
The bottle can manufacturing apparatus according to claim 4 includes a diameter reducing machine for reducing the diameter of the opening of the bottomed cylindrical can body, and a diameter increasing machine for expanding the diameter of the reduced diameter opening at a predetermined distance from the opening end. In a bottle can manufacturing apparatus comprising a screw forming machine that forms a screw at a certain distance from the opening end at a diameter-expanded portion and leaves a diameter-expanded portion where no screw is formed as a bulging portion, the same as the axis of the can body And a re-forming machine that presses and rolls a re-forming roller that is rotatable about a direction axis to the outer peripheral surface of the bulging portion.
[0013]
In this bottle can manufacturing device, after forming the screw, the re-forming roller can be rolled to the outer peripheral surface of the bulging part, and the bulging part can be re-molded. Variations in the shape and position of the bulge caused by the characteristics can be corrected.
[0014]
The bottle can manufacturing apparatus according to claim 5 is the bottle can manufacturing apparatus according to claim 4, wherein the remolding machine has at least three or more remolding rollers arranged at equal intervals in the circumferential direction. It is characterized by.
[0015]
In this bottle can manufacturing apparatus, three or more re-forming rollers can be pressed against the outer periphery of the bulging portion at the same time, and there is a misalignment between the center of the bulging portion and the center of the re-forming roller arrangement circle. It becomes possible to prevent.
[0016]
The bottle can manufacturing apparatus according to claim 6 is the bottle can manufacturing apparatus according to claim 4 or 5, wherein the re-forming roller has a bulging portion re-forming portion on an outer periphery on one end side in the axial direction. It has a relief part that does not have a larger outer diameter than the bulging part reshaping part on the outer periphery on the other end side in the direction.
[0017]
In this bottle can manufacturing apparatus, a bulging part that is relatively low in accuracy is required by a relief part that is formed so that the distortion generated when the bulging part is reshaped is not larger than the outer diameter of the bulging part remolding part. The upper part will be released, and the distortion of the lower part of the bulging part due to the spring back after re-molding will be prevented.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a bottle can manufacturing method and a bottle can manufacturing apparatus according to the present invention will be described in detail with reference to the drawings.
1 is a block diagram showing a re-forming machine in a bottle can manufacturing apparatus according to the present invention, FIG. 2 is a view taken along the line A-A in FIG. 1, and FIG. 3 is an enlarged view of a main part of the re-forming roller shown in FIG. 4 is a configuration diagram of a bottle can manufacturing apparatus provided with the remolding machine of FIG.
[0019]
The bottle can manufacturing apparatus according to the present embodiment is characterized by including a re-molding machine 31 shown in FIG. 1 in addition to conventional mechanisms such as a diameter-reducing machine, a diameter-expanding machine, and a screw forming machine, which will be described later. . The remolding machine 31 is fixed to the head support rod 33 via a support block 35 fixed to the outside of the head support rod 33. As shown in FIG. 2, the support block 35 rotatably holds three support shafts 39 at equal intervals on the circumference around the axis O of the bulging portion 37. The support shaft 39 has a support arm 41 fixed to the lower part and a support member 43 fixed to the upper part.
[0020]
Further, a torsion spring (biasing member) 45 is fitted to the support shaft 39. The torsion spring 45 has its lower end portion 45a fixed to the support shaft 39 and its upper end portion 45b fixed to the support block 35, so that the reshaping roller 47 is always in the direction of approaching the axis O in the direction of the support shaft 39 (support arm). 41, a torsion spring that urges the support member 43) to rotate. That is, the re-molding machine 31 can roll the three re-formable rollers 47 that are freely rotatable against the outer peripheral surface of the bulging portion 37 simultaneously.
[0021]
As shown in FIG. 2, the support arm 41 has one end in the longitudinal direction and rotatably supports the re-forming roller 47 via a shaft 49 in the same direction as the axis of the can body, and the other end bulges. It is fixed to a support shaft 39 provided along the axis О of 37, and rotates with the rotation of the support shaft 39 so that the re-forming roller 47 approaches or separates from the bulging portion 37. In this embodiment, an example of a structure in which three re-forming rollers 47 can be simultaneously pressed against the bulging portion 37 will be described. However, at least three or more re-forming rollers 47 are arranged at equal intervals in the circumferential direction. What is necessary is just to be arrange | positioned.
[0022]
By adopting such a pressing mechanism, the bulging portion 37 is simultaneously pressed against three or more re-forming rollers 47, and the center misalignment between the center of the bulging portion 37 and the center of the re-forming roller arrangement circle is caused. This prevents the bulging portion 37 from being reshaped with high roundness.
[0023]
A cam roller 53 is rotatably supported by the support member 43 via a cam shaft 51 provided at one end along the axis O. The cam roller 53 is brought into contact with a cone cam (not shown) provided so as to be movable up and down with respect to the head support rod 33, and the radial position with respect to the axis O is moved as the cone cam moves up and down. The other end of the support member 43 is engaged with the support shaft 39. When the cam roller 53 is moved by the cone cam, the support member 43 is rotated in the horizontal direction around the support shaft 39, and the support shaft 39, that is, the support arm 41 is rotated to move the re-forming roller 47 to the bulging portion 37. Approach or move away from each other.
[0024]
Further, as shown in FIG. 3, the reshaping roller 47 has a bulging portion reshaping portion 47a on the outer periphery on one end side in the axial direction (lower side in FIG. 3), and the other end side in the axial direction (upper side in FIG. 3). ) Has a relief portion 47b that does not have a larger outer diameter than the bulging portion re-forming portion 47a. The bulging portion re-forming portion 47a has a tapered shape with a gradually increasing diameter toward the lower side, and the inclined surface at the substantially central portion of the taper has a straight cross-sectional outline. The straight line portion 55 is formed with an angle of 48 degrees with the horizontal line 57, for example. The bulging portion re-forming portion 47 a re-shapes the bulging portion 37 by bringing the tapered surface into contact with the lower surface side of the bulging portion 37.
[0025]
Further, the relief portion 47b is formed so as to be continuous with the tapered surface and not to have a larger outer diameter than the bulging portion re-forming portion 47a. That is, it is formed with the same outer diameter as the bulging part re-forming part 47a or a smaller outer diameter than the bulging part re-forming part 47a. By providing such a relief portion 47b on the reshaping roller 47, distortion generated when the lower portion of the bulging portion, which is particularly required for accuracy, is reshaped is transferred from the bulging portion reshaping portion 47a to the escaping portion 47b. Thus, distortion of the lower portion of the bulging portion due to the spring back after re-molding is prevented.
[0026]
As shown in FIG. 4, the bottle can manufacturing apparatus 61 includes a main body frame 62 including a cylindrical holding cylinder 63 that rotates about a horizontal driving shaft. The holding cylinder 63 includes a plurality of accommodating portions 67 in the circumferential direction for accommodating and holding the can 65 in the horizontal direction. The holding cylinder 63 is rotated counterclockwise in FIG. 4 by a driving unit (not shown). The main body frame 62 includes supply means 68 that rotates around the horizontal axis so that a part of the outer periphery overlaps the outer periphery of the holding cylinder 63. The supply means 68 includes a plurality of gripping portions 69 that hold the can 65 supplied by the supply guide 68a in the circumferential direction. The supply means 68 can rotate in synchronization with the holding cylinder 63 to sequentially supply the can 65 supplied to the gripping portion 69 to the accommodating portion 67 of the holding cylinder 63.
[0027]
Further, the manufacturing apparatus 61 includes a discharge unit 71 in the vicinity of the supply unit 68. The discharge means 71 rotates around the horizontal axis such that a part of the outer periphery overlaps the outer periphery of the holding cylinder 63. The discharge means 71 includes a plurality of gripping portions 73 for holding the cans 65 discharged from the holding cylinder 63 in the circumferential direction, and sequentially supplies the cans 65 discharged to the gripping portions 73 to subsequent processes. ing.
[0028]
In this manufacturing apparatus 61, a diameter reducing machine 75, a diameter expanding machine 77, a screw forming machine 79, a curl processing machine 81, a slot processing machine 83, etc. are rotated along the circumferential direction of the holding cylinder 63. It arranges sequentially from the direction upstream to the downstream. The diameter reducing machine 75 performs a process of reducing the diameter of the opening of the bottomed cylindrical can 65 by using a plurality of drawing dies in stages. The diameter expanding machine 77 performs a process of expanding the diameter of the opening of the reduced diameter can 65 by a predetermined distance from the opening end. The screw forming machine 79 performs a process of forming a screw in the enlarged diameter portion at a certain distance from the opening end and leaving the enlarged diameter portion where no screw is formed as the bulging portion. The above-described remolding machine 31 is disposed on the downstream side of the machining process of the screw forming machine 79. That is, the re-forming machine 31 performs re-forming on the can 65 after the processing of the threaded portion and the bulging portion 37 by the screw forming machine 79 is completed.
[0029]
Next, operation | movement of the manufacturing apparatus 61 of the bottle can comprised as mentioned above is demonstrated with the procedure of the manufacturing method of a bottle can.
FIG. 5 is an enlarged view of the bulging portion before re-forming by the re-molding machine, and FIG. 6 shows the contour of the lower surface of the bulging portion at different positions in the circumferential direction of the bulging portion re-formed by the re-forming machine of FIG. It is explanatory drawing.
[0030]
When the can 65 formed into a cylindrical shape with a bottom in the previous process is supplied to the supply guide 68a, the bottle can manufacturing apparatus 61 causes the holding portion 69 of the supply means 68 to sequentially hold the can 65. The supply means 68 inserts the can 65 of the grip portion 69 into the storage portion 67 when the grip portion 69 coincides with the storage portion 67 of the holding cylinder 63. By repeating this operation, the cans 65 are sequentially supplied to the accommodating portion 67 of the holding cylinder 63.
[0031]
When the can 65 held in the accommodating portion 67 reaches the diameter reducing machine 75 by rotating the holding cylinder 63, the diameter reducing machine 75 reduces the diameter of the opening of the cylindrical can 65 (so-called neck-in processing). )I do. In this diameter reduction processing step, oiling, drawing (diameter reduction), trimming and the like are repeated a plurality of times.
[0032]
When the can 65 that has been subjected to the diameter reduction process reaches the diameter expansion machine 77 by the rotation of the holding cylinder 63, the diameter expansion machine 77 expands the diameter of the neck portion once reduced in diameter. At this time, in the diameter expansion process, when the predetermined distance is expanded from the opening end 85 shown in FIG. 5, the re-forming allowance Δh is estimated from the formation position h of the bulging portion 37 to the position H where the predetermined distance is extended. Expand the diameter.
[0033]
The can 65 subjected to the diameter expansion process then reaches the screw forming machine 79. The screw forming machine 79 performs a process of forming the screw portion 87 in the enlarged diameter portion at a constant distance from the opening end 85 and leaving the enlarged diameter portion where the screw portion 87 is not formed as the bulging portion 37.
[0034]
The can 65 in which the screw portion 87 and the bulging portion 37 are formed reaches the re-forming machine 31. The re-molding machine 31 presses and rolls the bulging part 37 already formed by the screw forming machine 79 from the outer periphery with the three re-forming rollers 47, thereby crushing the re-molding part Δh and Remold.
[0035]
The can 65 in which the re-forming of the bulging portion 37 has been completed in this way reaches the curling machine 81, the opening end 85 is bent outward, and then reaches the slot machine 83. The bent portion (curl portion) 89 is crushed, and the neck-in processing step of the can 65 and the screw portion / bulging portion forming step are completed.
[0036]
As described above, according to the bottle can manufacturing method described above, the re-forming roller 47 having a predetermined outer peripheral shape rolls on the outer peripheral surface of the bulging portion 37 so that the bulging portion 37 is re-formed. As shown, the bulging portion 37 having a uniform cross-sectional shape at an arbitrary position in the circumferential direction can be formed at a predetermined position. As a result, it is possible to uniformly wind the periphery of the opening of the cap around the bulging portion with a desired amount and angle of bending, resulting in a broken bridge, bending of the bent portion, around the cap, and a decrease in sealing performance. Disappear.
[0037]
Further, when expanding the predetermined distance from the opening end, the diameter is expanded to the position H where the predetermined distance is extended from the formation position of the bulging portion 37, so that the reshaping allowance Δh is expected. Even if the shape and position of the enlarged diameter portion varies due to processing accuracy or material anisotropy, and the bulging portion 37 becomes shallower than a predetermined value, the re-forming allowance Δh is set by the re-forming roller 47 during re-forming. It can be crushed and the bulging portion 37 can be reshaped into a predetermined position.
[0038]
According to the bottle can manufacturing apparatus 61, after forming the screw portion 87, the re-forming roller 47 can be rolled to the bulging portion 37, and the bulging portion 37 can be re-molded. Variations in the shape and position of the bulging portion 37 caused by processing and material anisotropy can be corrected.
[0039]
【The invention's effect】
As explained in detail above, according to the bottle can manufacturing method according to the present invention, after leaving a diameter-expanded portion where no screw is formed by forming a screw at a constant distance from the open end, Since the re-rolling roller having a predetermined outer peripheral shape rolls on the outer peripheral surface of the bulging portion to re-form the bulging portion, the bulging portion having a uniform cross-sectional shape at an arbitrary position in the circumferential direction is It can be formed in the position. As a result, the periphery of the opening of the cap can be uniformly wound around the bulging part with the desired amount and angle of bending, ensuring that bridge breakage, buckling of the bent part, rotation of the cap, and loss of sealing performance are reliably prevented. it can.
And, when expanding the predetermined distance from the opening end, the diameter is expanded to a position where the predetermined distance is extended from the formation position of the bulging portion by taking into account the re-molding allowance, so depending on the accuracy of diameter expansion processing and screw formation processing Even when the shape and position of the enlarged diameter part is uneven and the bulging part is shallower than the predetermined value, the re-molding allowance is crushed by the re-forming roller at the time of re-forming, and the bulging part is re-shaped to the predetermined position. Will be able to.
In addition, since three or more re-forming rollers are simultaneously pressed at equal intervals in the circumferential direction to perform re-forming, the misalignment between the center of the bulging portion and the center of the re-forming roller arrangement circle is prevented. The bulge can be reshaped with high roundness.
[0040]
According to the bottle can manufacturing apparatus of the present invention, the bottle can manufacturing apparatus includes a remolding machine that presses and rolls a remolding roller that is rotatable about an axis in the same direction as the axis of the can body against the outer peripheral surface of the bulging portion. Therefore, after forming the screw, the re-forming roller can be rolled to the outer peripheral surface of the bulging part, and the bulging part can be re-molded. It is possible to correct variations in the shape and position of the bulging portion that occurs.
Further, since the re-forming machine has at least three or more re-forming rollers arranged at equal intervals in the circumferential direction, re-forming is performed by simultaneously pressing the re-forming rollers at equal intervals in the circumferential direction of the bulging portion. It is possible to prevent misalignment between the center of the bulging portion and the center of the re-forming roller arrangement circle.
Further, the re-forming roller has a bulging portion re-forming portion on the outer periphery on one end side in the axial direction, and has a relief portion on the outer periphery on the other end side in the axial direction that does not have a larger outer diameter than this re-forming portion. Therefore, the distortion that occurs when the lower part of the bulging part, which requires particularly high accuracy, can be relieved to the upper part of the bulging part, which does not require relatively high accuracy, and Distortion can be prevented.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a re-molding machine in a bottle can manufacturing apparatus according to the present invention.
FIG. 2 is an AA arrow view of FIG.
FIG. 3 is an enlarged view of a main part of the re-forming roller shown in FIG.
4 is a configuration diagram of a bottle can manufacturing apparatus including the re-molding machine of FIG. 1;
FIG. 5 is an enlarged view of a bulging portion before re-forming by a re-forming machine.
6 is an explanatory view showing the contour of the lower surface of the bulging portion at different positions in the circumferential direction of the bulging portion re-formed by the re-molding machine of FIG. 1. FIG.
FIG. 7 is an explanatory diagram of a bottle can having a threaded portion and a bulging portion formed by a conventional bottle can manufacturing method and a cap attached to the bottle can.
FIG. 8 is an explanatory diagram showing a schematic procedure of a conventional method for manufacturing a bottle can.
FIG. 9 is an enlarged view of a bulging portion formed by a conventional bottle can manufacturing method.
FIG. 10 is an explanatory view showing the contour of the lower surface of the bulging portion at different positions in the circumferential direction of the bulging portion formed by a conventional bottle can manufacturing method.
[Explanation of symbols]
31 ... Re-forming machine 35 ... Can 37 ... Swelling part 47 ... Re-forming roller 47a ... Swelling part re-forming part 47b ... Relief part 49 ... Shaft 61 ... Bottle can manufacturing device 75 ... Diameter reducing machine 77 ... Diameter expanding machine 79 ... Screw forming machine 85 ... Open end 87 ... Screw Δh ... Reforming allowance

Claims (6)

After reducing the diameter of the opening of the bottomed cylindrical can body, the diameter of the opening is increased again by a predetermined distance from the opening end, and a screw is formed at a fixed distance from the opening end to thereby form an enlarged diameter portion where no screw is formed. In the manufacturing method of the bottle can left as the bulging part,
A method of manufacturing a bottle can, wherein after forming the screw, a re-forming roller having a predetermined outer peripheral shape is rolled on the outer peripheral surface of the bulging portion to re-mold the bulging portion. In the manufacturing method of the bottle can of Claim 1,
When expanding a predetermined distance from the opening end,
A method for manufacturing a bottle can, wherein the diameter is expanded to a position where the predetermined distance is extended by an amount corresponding to a re-forming allowance from a position where the bulging portion is formed. In the manufacturing method of the bottle can according to claim 1 or 2,
A method of manufacturing a bottle can, wherein three or more re-forming rollers are simultaneously pressed at equal intervals in the circumferential direction to perform re-forming. A diameter-reducing machine for reducing the diameter of the opening of the bottomed cylindrical can body, a diameter-expanding machine for expanding the diameter-reduced opening at a predetermined distance from the opening end, and a diameter-expanding part at a constant distance from the opening end. In a bottle can manufacturing apparatus comprising a screw forming machine that forms a screw and leaves a diameter-expanded portion where no screw is formed as a bulging portion,
An apparatus for manufacturing a bottle can, comprising: a re-forming machine that presses and rolls a re-forming roller that is rotatable about an axis in the same direction as the axis of the can body against the outer peripheral surface of the bulging portion. In the bottle can manufacturing apparatus according to claim 4,
The remolding machine
An apparatus for manufacturing a bottle can, wherein at least three or more of the re-forming rollers are arranged at equal intervals in the circumferential direction. In the bottle can manufacturing apparatus according to claim 4 or 5,
The re-forming roller is
It has a bulging part re-forming part on the outer periphery on one end side in the axial direction,
An apparatus for producing a bottle can characterized by having an escape portion that does not have a larger outer diameter than the bulging portion re-forming portion on the outer periphery on the other end side in the axial direction.

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