JP2687662B2 - Can neck forming equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] This invention, when manufacturing a beverage can, etc. The present invention relates to a can neck forming device used for forming.

[Prior Art] Generally, in cans such as aluminum cans for beverages, the engaging portion between the can body and the can lid is located outside the outer periphery of the can body so that it does not interfere with the packaging of the can. , Forming a neck with the periphery of the opening of the can body being inwardly narrowed, and crimping this neck with a can lid having a diameter smaller than the outer diameter of the can body, and this engaging portion is not on the outer periphery of the can body. Is being done. Also,
By reducing the diameter of the can lid, the cost of the can can be reduced.

It should be noted that this neck is not limited to one in which the tip portion of the can is thinly formed in one step, but there is also one in which the diameter is formed in a plurality of step shapes with two or more steps.

Conventionally, when molding a neck at the tip of the can, for example, a neck molding device as shown in FIGS. 6 (A), (B), (C), (D) and FIG. 7 has been used. There is.

This neck forming device is provided with a substantially cylindrical necking die 1.
And a columnar guide block 2 and a device main body (not shown) having a drive device, and the peripheral portion of the opening 3a of the can main body 3 inserted in the outer periphery of the guide block 2 is narrowed inward and the can main body 3 is formed. The guide block 2 is preliminarily advanced and inserted into the opening 3a of the can body 3 fixed to the main body of the device so that the neck 3b is formed on the neck block 3b.
By advancing along the axis of, the peripheral edge of the opening 3a of the can body 3 is pressed. A gap (clearance) 4 is provided between the guide block 2 and the necking die 1 so that the tip portion 3c, which is narrowed inside the can body 3, is sandwiched.

Then, as shown in FIG. 7 and the like, the necking die 1 is formed with a molding hole 1b having a circular cross section in which the opening 3a of the can body 3 is inserted into the die body 1a and the periphery of the opening 3a is narrowed inward. The molding hole 1b is opened in the front surface of the die body 1a, and a can insertion portion 1c is formed in this opening portion to expand the diameter toward the front to facilitate the insertion of a can, and behind the die body 1a. In order to mold the peripheral edge of the can body 3 toward the inner side of the opening 3a by narrowing when advancing along the axis of the can body, a molding portion 1d having a reduced inner diameter toward the rear is formed, The rear portion 1e of the rear molding hole 1b is formed in a cylindrical shape having the same inner diameter as the inner diameter of the rear end of the molding portion 1d.

The symbol L in FIG. 6 indicates the central axes of the can body 3, the guide block 2, and the molding hole 1b of the die body 1a.

Using such a neck forming device, the tip of the can body 3
When molding the neck 3b on 3c, first, see FIG. 6 (A).
As shown in, the can body 3 with the tip 3c opened before attaching the can lid is fixed to the device body, and the guide block is attached to the opening 3a of the can body 3 at the central axis L of the can body 3a. The guide block 2 is moved forward and inserted with the central axes L of the cans 2 aligned with each other so that the necking die 1 is aligned with the axis of the can body 3 and the central axis L of the can body 3 and the molding hole.
Match the central axis L of 1b and move forward.

As the necking die 1 advances, the molding portion 1d of the necking die 1 hits the tip portion 3c of the can body 3, and the neck molding portion 1d causes the tip portion 3c of the can body 3 to move.
Is narrowed inside the opening 3a.

Next, as shown in FIG. 6 (B), the tip portion of the can body 3
3c is squeezed so that its inner diameter is almost equal to the outer diameter of the guide block 2, enters the clearance 4 between the necking die 1 and the guide block 2, and is guided to the guide block 2. At this time, the tip portion 3c of the can body 3 is formed with a warped portion 3d which is curved outward.

Next, as shown in FIG. 6 (C), the necking die 1 is advanced as it is, and the tip 3c of the can body 3 is narrowed inside the opening 3a to lengthen the thinly formed portion. To form the neck 3b. At this time, the warped portion 3d is sandwiched between the necking die 1 and the guide block 2 and comes into contact with the necking die 1.

Then, as shown in FIG. 6 (D), a neck is attached to the can body 3.
3b is formed.

[Problems to be Solved by the Invention] By the way, when a neck is formed on a can body using the necking device, the necking die comes into contact with the warped portion and friction is generated to drive the necking die forward. It requires a great deal of power. Therefore, since it is necessary to press the necking die against the can body with a large force to mold the neck on the can body, a large molding load is applied to the can body, which may cause axial buckling of the can body. There was a problem that it would increase.

Therefore, it is conceivable to widen the clearance between the necking die and the guide block so that the warped portion does not contact the necking die. However, if the clearance between the neck forming part and the guide block is widened, the tip of the can body, which was pressed by the neck forming part of the advancing necking die and guided by the guide block, has a large clearance, so that it is seated in the circumferential direction. Molding proceeds while bending,
There is a problem that several wrinkles extending in the axial direction of the can body are formed, and it is necessary to make the clearance as narrow as possible in order to prevent the wrinkling in the axial direction. In particular, thin cans are prone to wrinkles, and it was necessary to narrow the clearance.

Therefore, it is not possible to widen the clearance between the guide block and the necking die to reduce the molding load at the time of neck molding, and to narrow the clearance to prevent wrinkling in the axial direction of the can body. However, there is a drawback in that it cannot be done because the molding load increases.

The present invention has been made in view of the above circumstances,
By reducing the molding load when molding the neck on the can body, axial buckling of the can body can be prevented and the clearance between the necking die and the guide block can be narrowed to mold the neck of a thin can. It is an object of the present invention to provide a can neck forming device that does not generate wrinkles.

[Means for Solving the Problems] In order to achieve the above object, in the can neck forming apparatus according to claim 1, a can body having a bottomed cylindrical can body is inserted into the outer periphery of a cylindrical guide block. A neck forming apparatus for a can, in which the periphery of the opening of the can body is narrowed inward by a necking die that moves along the axis of the can body to form a neck of the can, wherein the necking die inserts the opening of the can body. And a die body provided with a forming hole that narrows the periphery of the opening inward, and a can body when the die body is circumferentially provided in the forming hole of the die body and the die body is advanced along the axis of the can body. Has a ridge portion having a shape in which the peripheral edge of the ridge is narrowed toward the inside of the opening, and the inner periphery of the rear part of the molding hole of the die main body extends from the top of the ridge portion toward the rear end of the die body. Characterized by forming a tapered portion that expands in diameter It is assumed that.

Further, the can neck forming device according to claim 2 is the can neck forming device according to claim 1, wherein the inner circumference of the hole of the forming hole of the die body is replaced by a taper part and has a diameter larger than the inner diameter of the ridge. It is characterized by having a large annular groove.

Further, the can neck forming apparatus according to claim 3 is the can neck forming apparatus according to claim 1, wherein the die main body having a protruding portion at the rear end of the forming hole is used instead of the die main body having the tapered portion. It is characterized by comprising.

[Operation] In the can neck forming apparatus according to claim 1, a taper portion having a shape whose diameter increases from the top of the ridge toward the rear end of the die body is formed on the inner periphery of the rear portion of the forming hole of the die body. Due to this, the gap between the guide block and the taper part of the die body becomes wider toward the rear end of the die body, so when advancing the die body and forming the neck on the can body, , The warped portion formed after the tip of the can is narrowed inside the opening by the protrusion of the die body does not come into contact with the rear inner circumference of the molding hole of the die body,
Therefore, friction does not occur between the necking die and the warped portion.

In the can neck forming apparatus according to claim 2, the rear portion of the die body is replaced with a taper portion and an annular groove having a shape larger than the inner diameter of the ridge portion is formed.
Since the distance between the rear inner peripheral surface of the molding hole of the die main body and the guide block is wide as in the case of the neck forming device for a can described above, the warped portion and the rear inner periphery of the die main body do not come into contact with each other. There is no friction between the warped portion and the back of the necking die.

In the can neck forming apparatus according to claim 2, the die main body having a protruding portion at the rear end of the forming hole is provided in place of the die main body having the taper portion.
That is, since there is no portion that abuts the rear portion of the molding hole of the die body according to claims 1 and 2, the warped portion does not contact the inner circumference of the rear portion of the molding hole of the die body. There is no friction between the inner periphery of the molding hole and the rear inner periphery of the molding hole.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a drawing showing a necking die 10 of a can neck forming apparatus according to the first embodiment.

The can neck forming apparatus of this embodiment is obtained by replacing the necking die 1 of the conventional can neck forming apparatus shown in FIG. 6 and the like with the necking die 10 shown in FIG. 1 and the like. Constituent elements similar to those of the neck forming apparatus are attached with the same notations and an explanation thereof will be omitted.

The necking die 10 is provided with a die body 10a having a forming hole 10b for inserting the opening of the can body and purging the periphery of the opening inward, and is provided circumferentially within the forming hole 10b of the die body 10a. The die main body 10a has a ridge 10d having a shape that narrows the peripheral edge of the can main body 3 toward the inside of the opening 3a when the die main body 10a is advanced along the axis of the can main body 3, and At the inner periphery of the rear portion of the forming hole 10b, a tapered portion 10f having a shape in which the diameter is expanded from the top portion 10e of the protrusion 10d toward the rear end of the die body 10a.
Is formed.

That is, the necking die 10 is formed by forming the die body 1a on the inner periphery of the rear portion 1e of the molding hole 1b of the conventional necking die 1 described above.
The taper portion 10f is formed so that its diameter increases from the neck forming portion 1d toward the rear end of the die body 1a.

The inclination angle of the taper portion 10f with respect to the center axis of the die body 10a may be any number as long as the tip portion 3c and the taper portion 10f are not in contact with each other during neck molding.
In the embodiment of FIG.

When the neck 3b is molded on the can body 3 by using the neck molding device for a can of the first embodiment having such a necking die 10, as shown in FIGS. 2 (A), (B) and (C). ,
As shown in (D), the process is performed in the same manner as in the conventional can neck forming apparatus.

Next, using the conventional can neck forming apparatus and the can neck forming apparatus of the first embodiment, the necking die 1,
Table 1 shows the measurement results of the maximum forming load applied to the necking dies 1 and 10 when a two-stage neck 3b forming test was performed on the can body 3 while changing the clearance 4 between the guide block 2 and the guide block 2. Show.

The standard of the can sample used at this time is 350 Q / CV.
N (0.355t, 28kg material) F / W = 0.170 / 0.112.

Hexane lanolin was used as the wax at the time of molding, and it was dipped.

As is clear from Table 1, the neck forming device for a can of the first embodiment is different from the neck forming device for a conventional can described above in that the first neck 3b with the standard clearance 4 is used.
The load at the time of molding is 128.5 kg on the average in the conventional can neck molding apparatus, whereas it is 90.8 kg in the neck molding apparatus of the first embodiment, which is 37.7 kg lower.

Similarly, at the time of neck molding of the second stage, the conventional can neck molding device has a weight of 129.1 kg, whereas the neck molding device of the first embodiment has a molding load of 54.7 kg, which is 106.2 kg.

Moreover, in the conventional neck forming device, when the clearance 4 is standard, the neck forming load of the first stage is 128.5k.
On the other hand, when the clearance 4 is 0.025 mm narrower than the standard, it increases to 146.8 kg, but in the neck forming apparatus of the first embodiment, the standard is 90.8 kg, but it is 0.025 mm narrower than the standard. If you do, it is almost the same value as 92.1 kg.

Further, in the neck forming apparatus of the first embodiment, even if the clearance 4 is narrowed by 0.050 mm from the standard, the neck forming load of the first stage is 99.3 kg, which is only slightly increased from the standard. The value is lower than that of the standard clearance 4 of the conventional can neck forming device.

Therefore, the neck 3a of the can can be molded with a low molding load, the molding load is not easily affected by the clearance 4, and the neck molding can be performed with a low molding load even in a narrow clearance. .

After molding the neck 3b on the can body 3 with the can neck molding device of the conventional example and the first embodiment, no wrinkles or dents were found on the neck 3b portion of the can body 3.

Next, the necking dies 1 and 10 when performing a two-stage neck 3b forming test on a thin can using the conventional can neck forming apparatus and the can neck forming apparatus of the first embodiment described above.
Table 2 shows the measurement results of the maximum forming load applied to the.

The standard for thin cans used at this time is 350 Q / CVN (0.3
60t, 25kg material) F / W = 0.137 / 0.080.

Hexane lanolin was used as the wax at the time of molding, and it was dipped.

As is clear from Table 2, even in the neck forming of thin cans, the
The neck forming apparatus for a can of the embodiment has a low molding load of 44.3 kg on average in the first-stage neck molding and a low molding load of 20.5 kg on average in the second-stage neck molding. Therefore, the forming load can be reduced even in a thin-walled can having a weak axial strength of the can itself and easily buckling in the circumferential direction during molding.

Next, a can neck forming test is performed using the can neck forming device of the first embodiment and the conventional can neck forming device, and the neck forming load applied to the necking dies 1 and 10 at that time is measured. FIG. 3 (A) shows a result of the conventional neck forming apparatus for a can as a graph of a neck forming load curve, and FIG. 3 (B) shows a result of the can forming apparatus for a can of the first embodiment. It is shown as a graph of the neck forming load curve.

In the graphs of the neck forming load curves shown in FIGS. 3 (A) and 3 (B), the necking dies 1 and 10 are plotted on the Y axis.
The neck forming load (kg) was applied to the X axis, and the time for neck forming was taken on the X-axis.

About this measurement result, FIG. 2 (A), (B),
(C), (D) and FIGS. 6 (A), (B), (C),
The process of forming the neck of the can will be described later with reference to (D) and FIGS. 3 (A) and 3 (B).

Reference numeral a1 in FIG. 3A and reference numeral a2 in FIG.
As shown in FIGS. 2 (A) and 6 (A), as the necking dies 1 and 10 move forward, the neck forming portions 1d or the ridges 10d of the necking dies 1 and 10 are attached to the tip portion 3c of the can body 3. The load at the time of contact is shown. After this, the neck molding part
As the tip portion 3c of the can body 3 is narrowed inside the opening 3a of the can body 3 by the 1d or the protrusion 10d, the load applied to the necking die 1 and the necking die 10 is similarly increased.

Next, reference numeral b1 in FIG. 3 (A) and reference numeral in FIG. 3 (B)
As for b2, as shown in FIGS. 2 (B) and 6 (B), the tip 3c of the can body 3 is narrowed inside the opening 3a of the can body 3 to form the neck forming part 1d or the ridge. The load when passing through the top portion 10e of the portion 10d is shown. At this point, the tip portion 3c of the can body 3 is warped to form a warped portion 3d. At this point, the necking die 1 and the necking die
The loads on 10 and 10 show almost the same course.

Next, the code c1 in FIG. 3 (A) and the code in FIG. 3 (B)
As shown in FIG. 2 (C) and FIG. 6 (C), c2 shows that the necking dies 1 and 10 are moving forward, and the can body 3 opens rearward from the tip 3c of the can body 3. The load at the time of being narrowed and being thinly formed inside the portion 3a is shown.
At this point, in the conventional neck forming apparatus for a can, a load higher than that of the reference numeral b1 at the previous point in time is shown and there is an increasing tendency, whereas in the neck forming apparatus for a can of the first embodiment, , The code c1 of the conventional can neck forming device
The load is lower, and the load is almost the same as the code b2 at the previous time point, and is in a stable state. this is,
As shown in FIG. 6 (C), in the conventional can neck forming apparatus, the warped portion 3d of the can body 3 comes into contact with the rear portion 1e of the necking die 1 to cause friction, while FIG. As shown in C), in the can neck forming apparatus of the first embodiment, since the taper portion 10f is formed on the inner periphery of the rear portion of the forming hole 10b of the necking die 10, the bent portion of the can body 3 is bent. This is because 3d does not come into contact with the necking die 10 and friction does not occur between the warped portion 3d and the necking die 10.

Next, reference numeral d1 in FIG. 3 (A) and reference numeral in FIG. 3 (B)
d2 indicates the load at the time when the neck forming is completed as shown in FIG. 2 (D) and FIG. 6 (D). At this time, in the conventional neck forming apparatus for a can, the load has a maximum value and is as high as 144.0 kg as indicated by reference numeral d1, whereas in the neck forming apparatus for a can of the first embodiment, , A value as low as 106.0 kg, which is almost the same as the values shown by the reference signs b2 and c2 at the previous time point. This is also FIG. 2 (D).
As shown in FIG. 6 (D), in the conventional can neck forming apparatus, the warped portion 3d of the can main body 3 is in contact with the rear portion of the necking die 1, but the first embodiment In the can neck forming apparatus of the example, since the taper portion 10f is formed on the rear inner circumference of the forming hole 10b of the necking die 10, the warped portion 3d of the can body 3 does not contact the necking die 10 and the warped portion This is because friction does not occur between the 3d and the necking die 10.

As described above, according to the can neck forming apparatus of the first embodiment, the shape of the necking die 10 is changed to the rear end of the inside of the rear portion 1e of the forming hole of the die body 1a of the conventional can neck forming apparatus. By forming the tapered portion 10f having an inner diameter that increases toward the neck 3b, the necking die 10 does not come into contact with the warping portion 3d of the tip portion 3c of the can body 3 that can be formed when the neck 3b is formed. Friction does not occur between 10 and the curved portion 3d. Therefore, since the neck 3b can be formed on the can body 3 with a low forming load, it is possible to prevent the can body from buckling in its axial direction.

Further, since the warping portion 3d does not contact the necking die 10, even if the clearance 4 is narrowed,
Since the frictional force between the necking die 10 and the warped portion 3d does not increase and the molding load does not increase, the clearance 4 is narrowed to prevent wrinkles from being generated at the tip 3c of the can body 3 even in a thin can. be able to.

Further, the necking die 10 is simply formed by forming the taper portion 10f having a diameter increasing toward the rear end in the rear portion 1e of the molding hole 1b of the conventional necking die 1 described above.
Since it can be processed into a necking die 10,
It is possible to change from the conventional can neck forming device to the can neck forming device of the first embodiment from the conventional can neck forming device without much cost.

FIG. 4 is a view showing a necking die 20 used in a can neck forming apparatus according to a second embodiment of the present invention.

In the can neck forming apparatus of the second embodiment, the rear inner circumference of the forming hole 10b of the die body 10a of the necking die 10 of the can neck forming apparatus of the first embodiment is replaced with a tapered portion 10f. The necking die 20 is an annular groove 20a having a diameter larger than the inner diameter of the portion 10d. This necking die
The annular groove 20a of 20 is formed deeper than the inner peripheral surface of the top portion 10e of the protrusion 10d by at least 0.5 mm, that is ,. It is formed in a cylindrical shape having an inner diameter larger than the inner diameter of the top portion 10e of the protrusion 10d by at least 1 mm or more. This second
The method of using the can neck forming apparatus of the second embodiment is the same as that of the can neck forming apparatus of the first embodiment.

The operation and effect of the can neck forming apparatus of the second embodiment is almost the same as that of the can neck forming apparatus of the first embodiment, and the rear portion of the forming hole 10b of the die body 10a has a ridge. Ten
By forming the annular groove 20a having a diameter larger than the inner diameter of d, when the neck 3b is formed in the can body 3, the warped portion of the tip portion 3c of the can body 3 in the annular groove 20a of the forming hole 10b of the die body 10a.
Since the 3d does not come into contact, the neck 3b with a low forming load
Can be molded.

Therefore, while preventing the buckling of the can body in the axial direction,
The clearance 4 can be narrowed to prevent wrinkles from being generated at the tip 3c of the can body 3 even in a thin can.

FIG. 5 is a view showing a necking die 30 used in a can neck forming apparatus according to a third embodiment of the present invention.

The can neck forming apparatus of the third embodiment has a ridge 10b at the rear end of the forming hole 30b instead of the die body 10a having the tapered portion 10e of the can neck forming apparatus of the first embodiment. The die main body 30a is included. That is, the necking die 30 of the third embodiment has a structure in which the annular groove 20c of the necking die 20 of the second embodiment is cut off.

The method of using the can neck forming apparatus of the third embodiment is the same as that of the can neck forming apparatus of the first embodiment.

The operation and effects of the can neck forming apparatus of the third embodiment are almost the same as those of the can neck forming apparatus of the first embodiment, and when forming the neck 3b on the can body 3, Since a portion corresponding to the rear portion 1e of the molding hole 1b of the conventional die body 1a does not exist in the die body 30a of the second embodiment,
Since the necking die 30 does not come into contact with the warped portion 3d at the tip of the can body 3, the neck 3b can be molded with a low molding load.

Therefore, the buckling of the can body 3 in the axial direction can be prevented, and the clearance 4 can be narrowed to prevent wrinkles from being generated at the tip portion 3c of the can body 3.

Further, since the rear portions of the necking dies 1, 10, 20 are cut out, the material cost can be saved.

[Effects of the Invention] As described in detail above, according to the can neck forming apparatus of the present invention, the following effects can be obtained. By forming a taper part in the inner diameter of the rear part of the molding hole of the neck body, the diameter of which increases from the top of the ridge toward the rear end of the die body. Since the gap becomes wider toward the rear end of the die body, when the die body is advanced to form the neck on the can body, the ridges on the die body cause the tip of the can to open. Since the warped portion formed after being inwardly closed does not come into contact with the rear part of the die body, and there is no friction between the necking die and the warped portion, the molding load applied to the necking die during neck molding is reduced. Can be reduced.

Therefore, it is possible to prevent buckling of the can body, and also to set a small clearance between the necking die and the guide block to prevent wrinkles from being generated around the opening of the can body.

Further, the neck forming device for a can of the present invention can be obtained by simply processing the conventional necking die.

The rear portion of the die body is replaced with a taper portion and an annular groove having a diameter larger than the inner diameter of the ridge portion is formed, so that the gap between the rear portion of the die body and the guide block is the same as that of the neck forming device for a can according to claim 1. Since the warp portion and the rear part of the die body do not come into contact with each other, and there is no friction between the warp portion and the rear part of the necking die, the molding load applied to the necking die during neck molding can be reduced. Can be reduced.

Therefore, the buckling of the can body can be prevented, and the clearance between the necking die and the guide block can be set narrow to prevent wrinkles from being generated around the opening of the can body.

By providing a die body having a ridge at the rear end of the molding hole instead of the die body having the taper portion, that is, the necking die according to claim 1 or 2 has no rear portion. , Again, since the warped portion does not come into contact with the back of the necking die and friction does not occur between the warped portion and the back of the necking die, the molding load applied to the necking die during neck molding is reduced. be able to.

Therefore, it is possible to prevent buckling of the can body, and also to set a small clearance between the necking die and the guide block to prevent wrinkles from being generated around the opening of the can body.

In addition, the necking die has a shape in which the rear portion of the conventional necking die is cut off, which can save the material cost when manufacturing the necking die.

[Brief description of the drawings]

1 and 2 (A), (B), (C), and (D) are drawings showing a first embodiment of the present invention, in which FIG. 1 is a sectional view of an upper portion of a necking die, Figure 2 (A), (B),
(C) and (D) are sectional views showing the neck forming process of a can, FIGS. 3 (A) and (B) are graphs showing a forming load curve when forming a neck into a can, and FIG. 2 is a top sectional view of the necking die of the second embodiment, FIG. 5 is a top sectional view of the necking die of the third embodiment, FIGS. 6 (A) and 6 (B),
(C), (D) and FIG. 7 are drawings showing a conventional technique, and FIGS. 6 (A), (B), (C), and (D) are cross-sectional views showing a neck forming process of a can. , FIG. 7 is a cross-sectional view of a necking die. 1 ... Necking die, 1b ... Molding hole 2 ... Guide block, 3 ... Can body, 10 ... Necking die, 10a ... Die body, 10b ... Molding hole, 10d ... Ridge portion, 10e ... … Top of ridge 10f… Tapered part, 20… Necking die, 20a… Annular groove, 30… Necking die, 30a… Die body. 30b ...
… Molding holes.

Claims (3)

(57) [Claims] Claim: What is claimed is: 1. A bottomed cylindrical can body is inserted into the outer periphery of a cylindrical guide block, and the peripheral edge of the opening of the can body is
In a can neck forming device for forming a neck of a can by narrowing it inward by a necking die that moves along the axis of the can body, the necking die inserts the opening of the can body and purifies the periphery of the opening inward. And a die body having a forming hole that is provided circumferentially inside the forming hole of the die body, and when the die body is advanced along the axis of the can body, the peripheral edge of the can body faces the inside of the opening. A tapered portion having a ridge portion that is narrowed and having a shape in which the diameter increases from the top of the ridge portion toward the rear end of the die body is formed on the rear inner periphery of the molding hole of the die body. A neck forming device for a can, which is characterized in that 2. The can neck forming apparatus according to claim 1, wherein the inner peripheral portion of the rear portion of the molding hole of the die body is replaced with a taper portion, and an annular groove having a diameter larger than the inner diameter of the protrusion is formed. Can neck forming device. 3. The can neck forming apparatus according to claim 1, further comprising a die main body having a ridge at the rear end of the forming hole, instead of the die main body having a taper portion. Can neck forming device.