JP2617968B2 - Manufacturing method of neck-in can - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a so-called smooth neck-in can in which the opening end of a can body of a metal can containing drinking water or the like is gently narrowed.

(Prior Art) In recent years, in order to reduce the material of the can body by using a can lid smaller than the can body diameter as one measure of cost reduction of the can body, the opening of the can body engaging with the can lid is reduced in diameter. Attempts to do so are being considered.

Conventionally, the method of reducing the diameter of this can body opening end is
The so-called one-step neck-in processing method disclosed in JP-A-59-33046, JP-A-62-124038 or JP-A-62-235049
There is known a so-called smooth neck-in processing method in which a multi-stage neck-in portion is smoothed by spinning or the like.

However, in the method disclosed in Japanese Patent Publication No. 59-33046, the opening end B of the can body A is slid while the outer periphery of the can body A is slid on the guide surface 1a of the punch 1 as shown in FIG. The diameter is reduced along the drawing surface 2a of the die ring 2, and the opening end B is formed in the gap 4 between the inner surface 2b of the die ring 2 and the center ring 3.
The neck portion C and the neck-in shoulder portion D are formed by press-fitting the tip of the neck portion. In order to increase the diameter reduction of the neck portion C, the length of the drawing surface 2a of the die ring 2 is increased. Then, the joint area between the portion of the opening end B that is to be joined to the stop surface 2a and the stop surface 2a increases, and when the opening end B is slid into the stop surface 2a, the tip end is pressed into the gap 4. Since the frictional force increases, there is a concern that wrinkles or buckling may occur in the neck-in portion formed by the neck portion C and the neck-in shoulder portion D.

Further, in the method disclosed in JP-A-62-124038 or JP-A-62-235049, the diameter of the neck portion formed by repeating the method described in JP-B-59-33046 is repeated. By this, the diameter of the neck portion is reduced, but in order to smooth the neck-in shoulder formed in multiple steps, a roll or the like is pressed against this step and spinning is performed. The stripes are formed in the circumferential direction of the portion D, and the appearance is impaired, and the coating is easily peeled.

(Problem to be Solved) In order to cope with such a problem, the present invention provides a method for manufacturing a neck-in can that can surely and easily increase the diameter reduction amount without damaging the neck-in portion or deteriorating the appearance. The purpose is to do.

(Means for Solving the Problems) In order to achieve the above object, a method for manufacturing a neck-in can according to the present invention comprises a punch having a guide surface having substantially the same diameter and the same diameter as a can body, and being fitted inside the punch. A die ring having a stop surface of a predetermined taper angle and length connected to the guide surface, and an inner surface parallel to the axial direction connected to the stop surface, and a predetermined gap with the stop surface of the die ring. In the method for manufacturing a neck-in can using a forming die having a center ring, the opening end of the can body has a length equal to the length of the first die ring while the outer periphery of the can body is slid on the guide surface of the punch. A first neck-in shoulder reduced in diameter along the drawing surface of L1,
Further, the opening end is press-fitted into the gap between the inner surface of the first die ring and the first center ring, and has a predetermined length of about
A first step of forming a first neck of L2, and then a second step
The length L3 of the drawing surface of the die ring is L1 <L3 <L1 + L2, the taper angle of the drawing surface is the same as that of the first die ring, and other configurations are substantially the same as those of the forming die of the first step. The leading end of the first neck portion is moved to the second position while the outer periphery of the can body is slid in contact with the guide surface of the punch by using a forming die that is
Form a bent part with a reduced diameter along the drawing surface of the die ring,
Subsequently, the bent portion is pressed into a gap between the inner surface of the second die ring and the second center ring to form a second neck portion having a length of about L1 + L2-L3 and a length of about L3. A second step of forming a second neck-in shoulder having a gentle shape.

Further, the method for manufacturing a neck-in can according to the present invention includes a punch having a guide surface substantially coaxial and the same diameter as the can body, a predetermined length L1 fitted to the inside of the punch, and a predetermined length L1 and a taper connected to the guide surface. A first die ring having an angled stop surface, and an inner surface parallel to the axial direction connected to the stop surface;
A first forming die having a drawing surface of a die ring and a first center ring having a predetermined gap; and a drawing surface of the second die ring having a length of L3 and a taper angle of the drawing surface of the first die. The same as the ring, using a second molding die having the other configuration substantially the same as the molding die of the first step,
The first molding die mold is used to reduce the diameter of the open end of the can body along the drawing surface of the first die ring.
A first step of press-fitting the neck-in shoulder and the tip of the open end into the gap between the inner surface of the first die ring and the first center ring to form a first neck having a length of about L2; When,
Next, the first neck portion is deformed along the drawing surface of the second die ring by the second molding die and connected to the first neck-in shoulder portion in a substantially straight line, and has a gentle length of about L3. In a method for manufacturing a neck-in can in which a second neck-in shoulder having a shape is formed and a second neck portion having a length of about L1 + L2-L3 is formed, L1 and L3 are set to L1 <L3, and L2 is set to L3. −L1 <L2.

In addition, the method of manufacturing a neck-in can according to the present invention is characterized in that the tapered angles of the drawn surfaces of the first die ring and the second die ring are set to 20 ° or more and 35 ° or less.

(Operation) In the above means, the length L3 of the drawing surface of the second die ring in the second step is set to L1 <L3, thereby increasing the diameter reduction of the neck-in portion of the can body, and further increasing the length. L3 to L3
By making L1 + L2 or L3−L1 <L2, the tip of the first neck portion is brought into contact with the middle portion of the throttle surface of the second die ring to form the bent portion. And
The bent portion can be press-fitted into the gap between the inner surface of the second die ring and the center ring, and the joint area between the bent portion and the throttle surface during the press-fitting can be reduced.

Further, by making the tapered angles of the drawing surfaces of the first and second die rings the same, when the forming of the first neck portion by the second die ring is completed, the drawing of the second die ring of the first neck portion is completed. The portion formed along the surface is connected to the first neck-in shoulder in substantially the same straight line, and the gentle second neck-in shoulder is formed to increase the diameter reduction.

(Example) Hereinafter, an example of the method according to the present invention will be described in detail.

First, the first step will be described with reference to FIGS.

In FIG. 1, A is a can body, and 1, 2, and 3 respectively denote the punch, the first die ring, and the first center ring which are arranged coaxially with the can body A in the first molding die. Show.

The inner surface of the punch 1 near the opening facing the can body A is provided with the guide surface 1a having a slight taper, and the end of the first die ring 2 has a taper angle of 30 ° and the length L1. Aperture surface 2a and an inner surface portion 2b continuous with the aperture surface 2a.

Further, reference numeral 4 denotes the gap provided between the inner surface 2b of the first die ring 2 and the first center ring 3, and reference numeral 5 surrounds the first center ring 3 and It is an adapter that slides.

The bottom portion A 'of the can body A is held by a can holder 6, and the punch 1 and the first die ring 2 are fixed to a holder necking die 7.

Further, the first center ring 3 is slidably fitted to a bolt 8 fixed coaxially with the holder necking die 7, and further urged toward the can body A by a spring 9.

The first forming die was moved to the can body A side by a driving device (not shown), and the outer periphery of the can body A was slid on the guide surface 1a of the punch 1.

Thereafter, the die is further moved to bring the outer end of the can body A into sliding contact with the inner surface 1a of the punch 1 as shown in FIG. The diameter was reduced and bent along the surface 2a.

Further, the mold is moved and the open end B is press-fitted into the gap 4 between the inner surface 2b of the first die ring 2 and the first center ring 3 while the distal end abuts against the adapter 5 as shown in FIG. And said first neck portion C having a length of about L2 and a length of about L1
And the first neck-in shoulder D of the above.

Next, the second step will be described with reference to FIGS.

The second molding die used in the second step is the second molding die.
At the length L3 of the drawing surface 2a 'of the die ring 2', the taper angle is the same as that of the first die ring 2, that is, 30 degrees, and other configurations are the same as those of the first molding die used in the first step. They are almost the same.

First, as shown in FIG. 4, after the can body A processed in the first step is fixed to the can holder 6, the outer periphery of the can body A is brought close to the guide surface 1a of the punch 1 by approaching the second molding die. The first neck portion C formed in the first step while being in sliding contact with the first neck portion C
Of the second die ring 2 'was brought into contact with the stop surface 2a' of the second die ring 2 '.

Next, the mold was further moved, and the first neck portion C was reduced in diameter along the drawn surface 2a 'and bent to form a bent portion E as shown in FIG.

Thereafter, the mold was continued to move and the bent portion E was pressed into the gap 4 between the inner surface portion 2b 'of the second die ring 2' and the second center ring 3 'as shown in FIG.

As a result, as shown in FIG. 7, the neck-in portion comprising the second neck portion C 'having a length of about L1 + L2-L3 and the gentle second neck-in shoulder portion D' having a length of about L3. Was able to be molded.

Further, according to the method of the present invention, the third step for the second step having the same relationship as the second step for the first step is performed.
By repeating the steps, it is possible to further reduce the diameter of the second neck portion C ′ formed in the second step as shown in FIG. 8 to further increase the diameter of the opening end B of the can body A. it can.

In the above embodiment, the can body A can be used for both two-piece and three-piece can bodies, and the material of the can body A may be aluminum, tinplate or tin-free.

Note that, specifically, the above L1, L2 and L3 are 2.76 mm, 9.04 mm
And 4.74 mm. Further, when the taper angles of the throttle surfaces 2a and 2a 'of the first and second die rings are set to 20 ° or less, the diameter of the opening end B of the can body A can be reduced to a desired degree as in the above embodiment. If the diameter is increased, the length of the second neck-in shoulder D 'becomes longer, and the material cost of the can body A increases.

Further, when the taper angles of the throttle surfaces 2a and 2a 'are set to 35 ° or more, the frictional resistance between the throttle surfaces 2a and 2a' and the open end B of the can body A to be joined increases, and the can body A is seated. Easy to buckle.

(Effect) Therefore, according to the method of the present invention, when the length of the drawing surface of the first die ring in the first step is L1 and the length of the first neck portion is about L2, By making the length L3 of the drawing surface of the second die ring in the process L1 <L3 <L1 + L2, the amount of diameter reduction of the neck-in portion of the can body is increased, and the tip of the first neck portion is moved to the second position. The bent portion is formed by being brought into contact with an intermediate portion of the drawing surface of the die ring, and the bent portion can be pressed into a gap between the inner surface portion of the second die ring and the second center ring, and At the time of the press-fitting, the joining area between the bent portion and the throttle surface can be reduced.

Further, by making the tapered angles of the drawing surfaces of the first and second die rings the same, when the forming of the first neck portion by the second die ring is completed, the drawing of the second die ring of the first neck portion is completed. Since the portion formed along the surface can be connected to the first neck-in shoulder in substantially the same straight line to form the gentle second neck-in shoulder,
A method for manufacturing a neck-in can that can surely and easily increase the diameter reduction amount without damaging the neck-in portion or impairing the appearance can be provided.

In addition, L1 and L3 are set to L3 <L1, and L2 is set to L3−
By setting L1 <L2, the same effect as described above can be obtained.

Furthermore, if the taper angle of the drawing surface is set to 20 ° or more and 35 ° or less, it is possible to manufacture the preferable neck-in portion without increasing the material cost of the can body and without buckling the can body. Can be.

[Brief description of the drawings]

1 to 8 are an explanatory sectional view and a partial sectional view illustrating an embodiment of the method according to the present invention, and FIG. 9 is a partial sectional view illustrating a conventional method. DESCRIPTION OF SYMBOLS 1 ... Punch 1a ... Punch guide surface 2 ... 1st die ring 2 '... 2nd die ring 2a, 2a' ... Drawing surface 2b, 2b '... Inner surface part 3 ... 1st center ring 3 '... Second center ring 4 ... Gap A ... Can body B ... Open end C ... First neck part C' ... Second neck part D ... First neck-in shoulder part D '... 2nd neck-in shoulder

Claims (3)

(57) [Claims] 1. A punch having a guide surface substantially coaxial with and the same diameter as a can body, a throttle surface fitted to the inside of the punch and having a predetermined taper angle and length connected to the guide surface, and the throttle surface. A method of manufacturing a neck-in can using a forming die including a die ring having an inner surface portion parallel to the axial direction and a center ring having a predetermined gap between the drawn surface of the die ring and the punch. A first neck-in shoulder portion in which the opening end of the can body is reduced in diameter along the drawing surface having a length L1 of the first die ring while the outer periphery of the can body is in sliding contact with the guide surface;
Further, the opening end is press-fitted into the gap between the inner surface of the first die ring and the first center ring, and has a predetermined length of about
A first step of forming a first neck of L2, and then a second step
The length L3 of the drawing surface of the die ring is L1 <L3 <L1 + L2, and the taper angle of the drawing surface is the same as that of the first die ring. The leading end of the first neck portion is moved to the second position while the outer periphery of the can body is slid in contact with the guide surface of the punch by using a forming die that is
Form a bent part with a reduced diameter along the drawing surface of the die ring,
Subsequently, the bent portion is pressed into the gap between the inner surface of the second die ring and the second center ring to form a second neck portion having a length of about L1 + L2-L3 and a length of about L3. A second step of forming a second neck-in shoulder having a gentle shape. 2. A punch having a guide surface substantially coaxial with the can diameter and having the same diameter as the can body, a stop surface fitted to the inside of the punch and having a predetermined length L1 and a taper angle connected to the guide surface, and the stop. A first molding die having a first die ring having an inner surface portion parallel to the axial direction connected to a surface, and a first center ring having a predetermined clearance with a drawing surface of the first die ring;
The second molding in which the length of the drawing surface of the second die ring is L3, the taper angle of the drawing surface is the same as that of the first die ring, and the other configuration is substantially the same as the forming die in the first step. A first neck-in shoulder having a length of about L1 obtained by reducing the opening end of the can body along the drawing surface of the first die ring by using the first molding die, using a die mold; A first step of press-fitting the opening end tip into a gap between the inner surface of the first die ring and the first center ring to form a first neck portion having a length of about L2; The first neck portion is deformed along the drawing surface of the second die ring by a die and connected to the first neck-in shoulder portion in a substantially straight line to form a smooth second neck having a length of about L3. How to make a neck-in can that forms a second neck with a length of about L1 + L2-L3 while forming the shoulder In, the L1 and L3 L1 <
L3, and said L2 is L3-L1 <L2. 3. The method for producing a neck-in can according to claim 1, wherein the tapered angles of the drawing surfaces of the first die ring and the second die ring are not less than 20 ° and not more than 35 °.