JP2006001619A - Method for producing bottle shaped can - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a bottle shaped can having a mouth/neck part, a shoulder part, a body part and a bottom part integrally formed, the method which easily forms a screw part even when the diameter of the mouth/neck part is small without deforming the screw part by enlarging the gap of the screw pitch and satisfactorily forming the screw part without damaging the film coating of the can surface by the screw part. <P>SOLUTION: After forming a screw part 2c by screw processing using an inner roll and an outer roll, a small diameter short cylindrical part n1 which is a scheduled curl processing part is formed on a short cylindrical part above the part 2c by short diameter processing. The part n1 is curl-processed to form an outward curled part. In screw processing, such an inner roll is used that the ratio (d1/d2) between the inside diameter d1 of a scheduled screw processing part and the outer diameter d2 of the inner roll is in the range of 1.0-1.4. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a bottle-shaped can in which a mouth-and-neck portion, a shoulder portion, a trunk portion, and a bottom portion are integrally formed, and in particular, in such a bottle-shaped can manufacturing method, an inner roll and an outer roll When the threaded part is formed on the peripheral wall of the mouth and neck, the threaded part can be easily formed even if the diameter of the mouth and neck is small, and the screw pitch can be shifted. The present invention relates to a method for manufacturing a bottle-type can that can be formed well without distorting the screw portion and without damaging the coating film on the surface of the can with the screw portion.

  As a method for manufacturing a bottle-shaped can in which the mouth and neck, shoulder, body, and bottom are integrally molded, a cup punched from a thin metal plate is drawn and ironed to obtain a bottom and body. After forming into a bottomed cylindrical can that is integrally molded, the opening end side of the thinned cylindrical body is reduced in diameter (necking) to form a slanted shoulder and a small-diameter cylindrical mouth After forming a bottle-shaped intermediate product by molding on the neck, the mouth and neck are molded into the final shape by molding the curled part of the open end and the threaded part of the peripheral wall to the mouth and neck part. A manufacturing method of such a bottle-shaped can is conventionally known as described in the following patent documents, for example.

  In addition, regarding the method of manufacturing such a bottle-shaped can, the following Patent Document 2 describes that “the curled part and the screw part are formed on the mouth and neck part and the mouth and neck part is formed into the final shape”. When it is desired to form a thread portion such as a single thread or a deformed multiple thread screw on the neck portion, it may be performed at an appropriate stage at the time of drawing the neck portion or may be formed in a separate process. It is done. And from this description, for the step of reducing the diameter near the upper end of the mouth neck (neck) and forming the small-diameter short cylindrical portion (and the inclined portion below it) that will be the curled portion, The screw forming process for forming the screw portion by applying the screw processing to the lower screw processing scheduled portion may be performed later, simultaneously, or before. It is thought that it is suggested by the patent document 2 of this.

Further, in Patent Document 3 below, “After forming the threaded portion on the neck, further drawing the upper tip portion to form a small-diameter portion.” “Externally facing the small-diameter portion made thin. "Curling is applied." In other words, from this description, after the threaded portion of the neck and neck (neck portion) is threaded, the diameter of the tip of the mouth is further reduced, and the small diameter short cylindrical portion (small diameter portion) It is recognized that Patent Document 3 below discloses that the small-diameter short cylindrical portion (small-diameter portion) is subjected to curling to form a curled portion.
Japanese National Patent Publication No. 10-509095 Japanese Patent Laid-Open No. 1-210136 JP 2003-94133 A

  By the way, in the manufacture of a bottle-shaped can in which the mouth / neck part, the shoulder part, the body part, and the bottom part are integrally formed, the screw forming process when the mouth / neck part is formed into the final shape is described in Patent Documents 2 and 3 above. Although it is suggested that the screw forming is performed before the diameter of the upper end of the mouth-neck part is reduced to the curl-scheduled part, conventionally, the body of the bottomed cylindrical can is generally used. A bottle-shaped intermediate molded product that is formed on the mouth neck and shoulders by reducing the diameter of the opening end side, near the upper end of the mouth neck and the small-diameter short cylindrical part that will be the curled part and below And then curling the small-diameter short cylindrical part above the inclined part to form an outer curled part and inclining it. A threaded portion is formed by threading a threaded portion that is below the portion.

  In addition, as a threading method at that time, an inner roll inserted into the mouth and neck and an outer roll arranged on the outer periphery of the mouth and neck are used, and the neck and neck are interposed between the inner roll and the outer roll. The inner roll connected to the drive source is driven to revolve along the inner peripheral surface of the mouth and neck while rotating, with the peripheral wall (scheduled part to be machined) sandwiched, and synchronized with this inner roll. The outer rolls that are rotatably supported are revolved along the outer peripheral surface of the mouth and neck while rotating, and each roll is revolved while revolving so as to have substantially the same peripheral speed. Conventionally, it is generally performed that a screw is roll-formed on the peripheral wall (scheduled part of the screw processing) of the mouth and neck by working.

  On the other hand, the bottle-shaped can with the mouth / neck, shoulder, torso, and bottom integrally formed reduces the material cost of the cap, and the consumer drinks the beverage by placing the mouth directly on the mouth / neck. In view of ease of drinking at times, it is desired to reduce the diameter of the mouth and neck. Further, regardless of the diameter of the mouth and neck, for example, the ratio (d3 / d4) of the outer diameter d3 of the threaded portion to the inner diameter d4 of the small-diameter short cylindrical portion after the diameter reduction processing is 1.1 or more. In addition, it is necessary to sufficiently reduce the diameter of the vicinity of the upper end of the mouth and neck portion as compared with the screw portion below the mouth and neck portion.

  That is, when the diameter of the mouth and neck near the upper end is insufficient (the degree of diameter reduction is smaller than the screw part below it), the curled part of the outer winding formed at the opening end of the mouth and neck The difference between the outer diameter of the screw portion and the outer diameter of the screw portion formed therebelow is small. As a result, the screw portion of the cap screwed with the screw portion of the mouth-and-neck portion is There is a possibility that it becomes difficult to attach and detach the cap by interfering with the curled portion at the opening end.

  In consideration of such a situation, when threading the mouth-and-neck part of the bottle-shaped intermediate molded product by the above-described threading method, for example, the inner diameter of the threaded scheduled part of the peripheral wall of the mouth-and-neck part For a bottle-shaped intermediate molded product of about 28 mm, after reducing the diameter of the vicinity of the upper end of the mouth-and-neck part into a small-diameter short cylindrical part to be curled and a lower inclined part, the inner diameter of the opening end Is about 20 mm, it becomes difficult to insert the inner roll into the mouth-and-neck portion during subsequent screw machining. Moreover, even if the inner roll is inserted into the mouth and neck before the diameter reducing process and then the diameter reducing process and the screw processing are performed at the same time, it is difficult to pull out the inner roll from the mouth and neck. Become.

  In other words, even if the inner roll can be taken in and out even after the upper end of the mouth and neck is reduced in diameter, the inner roll has a drive mechanism for revolving while rotating, even if the outer diameter of the inner roll is reduced. Since there is a limit to reducing the outer diameter of the inner roll, it is necessary to match the inner diameter of the open end after diameter reduction processing, especially when the diameter of the mouth and neck is small. This makes it difficult to reduce the outer diameter of the inner roll. Moreover, even if the outer diameter of the inner roll can be reduced so that it can be taken in and out even after the upper end of the mouth-neck portion has been reduced, the screw pitch shifts during screw processing for the reasons described later. Increases and distortion occurs in the screw portion, so that there is a possibility that the screw molding cannot be performed satisfactorily.

  Therefore, for the bottle-shaped intermediate molded product in which the mouth / neck part, shoulder part, body part, and bottom part are integrally molded, the diameter near the upper end of the mouth / neck part is reduced to a small-diameter short cylindrical part and an inclined part. From the above, do not thread the threaded part below the inclined part, but conversely, apply the threaded part to the threaded part of the peripheral wall of the mouth and neck, and then place the inner roll inside the mouth and neck. From the contents described in Patent Documents 2 and 3 above, it is natural to reduce the diameter of the portion above the already formed screw portion into a small-diameter short cylindrical portion and an inclined portion. Conceivable.

  However, although it is suggested in the above-mentioned Patent Document 2 that the timing of the screw forming process may be appropriately selected, the screw processing tools (inner roll and outer roll) used at the time of screw processing are particularly described. Therefore, in the invention described in the above-mentioned Patent Document 2, the screw machining tools (inner roll and outer roll) to be used can be used regardless of the timing of the screw forming process (the mouth). It is considered that an inner roll having a small outer diameter that can be used even when screwing is performed after reducing the diameter near the upper end of the neck.

  Further, in Patent Document 3 described above, after a threaded portion of the neck and neck portion (neck portion) is subjected to screw processing, the "mouth tip portion" above is further subjected to diameter reduction processing to form a small-diameter short cylindrical portion. (Small-diameter part), but this "mouth part" is threaded in a state before being reduced (drawn) into a small-diameter short cylindrical part (small-diameter part) to be curled. The part that has already been reduced to a smaller diameter than the part to be threaded before being used, and the inner roll used as a threading tool must have a small outer diameter that can pass through this "mouth part" There is. Therefore, when manufacturing a bottle-type can having a small diameter at the mouth and neck, it is necessary to set the outer diameter of the inner roll to be smaller than the limit, and in practice, screw processing becomes impossible. There is a fear.

  Moreover, in any case, when manufacturing a bottle-shaped can in which the mouth and neck, the shoulder, the body and the bottom are integrally formed, before the diameter reduction processing is performed near the upper end of the mouth and neck, Even if the molding process can be completed, if the outer diameter of the inner roll is made too small for that purpose, the difference between the inner diameter of the threaded planned portion of the neck and neck and the outer diameter of the inner roll (that is, , The difference in circumference of the two) is increased, and the ratio of the screw range that can be formed by one rotation of the inner roll in the circumferential direction of the threaded portion of the mouth and neck is reduced, so that The deviation of the pitch of the screw formed in the portion to be screw processed becomes large, and the screw processing at the end of screw processing overlaps the portion of the screw formed at the start of screw processing. As a result, there is a possibility that the screw portion is distorted and the function as a screw is hindered.

  In the past, when the screw processing is performed after the upper neck portion of the mouth and neck portion has been reduced to a small diameter short cylindrical portion to be a curled planned portion, naturally, the inner diameter of the planned screw processing portion is naturally. Therefore, an inner roll having a considerably smaller outer diameter is used. In such a case, adjust the number of rotations of the inner roll and outer roll so that the deviation in the pitch of the screws formed in the threaded portion of the neck and neck does not become large, and screw forming while slipping the roll. In that case, in order to eliminate the displacement of the pitch of the screw so that the entire screw is not distorted, the number of rotations of each roll is controlled to an appropriate value. It becomes necessary, and the productivity is inferior due to the difficulty of the control, and there is a possibility that the coating film on the surface of the can may be damaged by the friction due to the slip.

  The present invention has an object to solve the above-described problems, and specifically, a method for producing a bottle-shaped can in which a mouth / neck portion, a shoulder portion, a trunk portion, and a bottom portion are integrally formed. The screw part can be easily molded even if the diameter of the mouth and neck part is small, and the screw surface can be distorted without increasing the screw pitch deviation, and the screw part can It is an object of the present invention to make it possible to satisfactorily mold the screw part without damaging the coating film.

  In order to solve the above-described problems, the present invention forms a bottomed cylindrical can in which a bottom portion and a body portion are integrally formed from a thin metal plate material by performing at least drawing processing and ironing processing, and then reducing the thickness. After the diameter of the opening end side of the cylindrical body formed is reduced to a slanted shoulder and a small-diameter cylindrical mouth-and-neck, a bottle-shaped intermediate molded product is formed. On the other hand, in the method of manufacturing a bottle-type can where the mouth and neck are formed into a final shape by molding the curled part of the open end and the threaded part of the peripheral wall, etc. When forming into a shape, after threading the inner and outer rolls and forming the threaded portion of the neck and neck into a threaded portion, at least once with respect to the short cylindrical portion above it Curl processing to small diameter short cylindrical part after diameter reduction processing When the outer curled portion is formed and screwed, the ratio (d1 / d2) between the inner diameter d1 of the threaded portion of the mouth and neck portion and the outer diameter d2 of the inner roll is 1.0 to An inner roll that falls within the range of 1.4 is used.

  According to the manufacturing method of the bottle-shaped can of the present invention as described above, the screw for the mouth-and-neck portion of the bottle-shaped intermediate molded product in which the mouth-and-neck portion, the shoulder portion, the trunk portion, and the bottom portion are integrally formed. Compared to the reverse case, after forming the screw part by applying the screw processing to the part to be processed, the diameter of the upper part is reduced to form the small diameter short cylindrical part that will be the curled part. When threading, an inner roll having a large outer diameter can be used as a threading tool inserted into the mouth and neck. As a result, even when a bottle-shaped can having a small diameter at the mouth and neck is manufactured, an inner roll having an outer diameter suitable for the bottle can can be easily prepared.

  When screwing, the ratio (d1 / d2) of the inner diameter d1 of the portion to be screwed of the neck and neck to the outer diameter d2 of the inner roll is in the range of 1.0 to 1.4. Because using the inner roll with a relatively large outer diameter (close to the inner diameter of the threaded portion), the difference between the inner diameter of the threaded portion and the outer diameter of the inner roll is reduced. It is possible to increase the ratio of the range of screws that can be formed by one rotation of the inner roll in the circumferential direction of the thread processing scheduled part, and to adjust the number of rotations of the inner roll and outer roll to slip the roll. Without any problem, only by synchronizing the outer roll with the rotation of the inner roll and interlocking it, the deviation of the pitch of the screw in the circumferential direction of the mouth-and-neck portion can be reduced. As a result, the threaded portion can be formed satisfactorily without almost distorting the threaded portion, the complicated rotation control of each roll is not required, and the can surface is coated with the threaded portion by friction due to slip. There is no damage to the membrane.

  In addition, it is possible to satisfactorily perform screw processing using such an inner roll having a large outer diameter, and when reducing the diameter of the upper portion of the processed screw portion, for example, the outer diameter d3 of the screw portion. Since the diameter of the screw portion can be sufficiently reduced so that the ratio (d3 / d4) of the inner diameter d4 of the small-diameter short cylindrical portion after diameter reduction is 1.1 or more, the final shape was formed. When the cap is attached to the mouth and neck portion, the curl portion formed above the screw portion and the screw portion of the cap do not interfere with each other so that the cap is not easily attached and detached.

  Furthermore, since the curled portion is formed after the screw portion is formed on the mouth and neck portion, the lateral push applied to the mouth and neck portion from the screw processing tool (inner roll or outer roll) at the time of screw processing is performed. Even if the roundness near the upper end of the mouth and neck decreases due to pressure, the roundness of the curled part should be corrected by the curling tool inserted inside the mouth and neck during subsequent curling. As a result, by increasing the roundness of the curled portion, it is possible to improve the sealing performance between the sealing member of the cap and the curled portion that is attached to the mouth and neck portion.

  Regarding the method for manufacturing a bottle-shaped can in which the mouth / neck, shoulder, body, and bottom are integrally molded, the screw part can be easily formed even if the diameter of the mouth / neck is small, and The purpose of making it possible to mold the screw part well without increasing the screw pitch deviation and distorting the screw part, and without damaging the paint film on the can surface with the screw part, As specifically shown in the following examples as the best mode, when the mouth-and-neck portion of the bottle-shaped intermediate molded product is molded into the final shape, the mouth-and-neck portion is subjected to screw processing with an inner roll and an outer roll. After forming the part to be threaded into a threaded part, at least one diameter reduction process is applied to the short cylindrical part above it, and then the reduced diameter small cylindrical part is curled. Molded on the outer curl and threaded When using the inner roll, the ratio (d1 / d2) of the inner diameter d1 of the threaded portion of the mouth and neck to the outer diameter d2 of the inner roll is in the range of 1.0 to 1.4. It was realized by doing.

  Hereinafter, an embodiment of the method of the present invention will be described. As shown in FIG. 1, in a bottle-shaped can 1 manufactured by the method of this embodiment, a dome-shaped bottom portion 5 and a cylindrical body portion 4 are provided. A small-diameter cylindrical mouth-and-neck part 2 is integrally formed above the large-diameter cylindrical body part 4 via an inclined shoulder part 3 formed in a dome-like convex curved surface. Is formed. The mouth-and-neck portion 2 is formed with an outer curled portion 2a at the opening end of the upper end thereof, and an inclined portion 2b having a diameter reduced upward is formed below the curled portion 2a. A screw portion 2c is formed, and an annular convex portion 2d and an annular concave portion (groove portion) 2e are formed below the screw portion 2c. Although not shown in the drawings, the mouth-and-neck portion 2 is made of a metal-made separate pilfer-proof cap that is rolled on by a well-known cap mounting device (capper) after the beverage is filled in the can. By being molded, it is mounted so that it can be resealed (resealed) by screwing.

  Such a bottle-shaped can 1 in which the neck 2, the shoulder 3, the body 4, and the bottom 5 are integrally formed is formed into a metal thin plate material (a conventionally well-known aluminum-based or steel-based metal thin plate material for appropriate making) The outline of the manufacturing process for manufacturing from (1) will be described. First, a cylindrical cup is punched out of the thin metal plate with a cupping device using a thin metal plate that has been previously coated with a lubricant. A machine (body maker) equipped with a drawing die, multiple (usually three) ironing dies and punches, while drawing lubricant on the cup, and drawing ironing by redrawing and multiple ironing operations. By applying to the cup, the cup is formed into a bottomed cylindrical can in which the bottom and the body are integrally formed. The ironing process at that time may be performed by a plurality of ironing apparatuses.

  Next, after trimming the open end of the bottomed cylindrical can, it is conveyed while being inverted on a net conveyor, or while being held inverted by a pin chain and conveyed. After performing cleaning and chemical conversion treatment by spraying preliminary cleaning water, degreasing liquid, cleaning water, chemical conversion liquid, cleaning water, and final cleaning water (pure water) from above and below the bottom cylindrical can After printing and painting on the outer surface of the can, the can is heated to dry the printed coating, the outer surface of the bottom is also painted, the coating is heated to dryness, and the inner coating on the inner surface of the can After spraying the can, heat the can and dry.

  Next, in the neck-in processing step by a plurality of devices arranged along the can conveying direction, the cans are sequentially passed through each device, and a plurality of times (for example, 13 to 14) with respect to the opening end side of the bottomed cylindrical can. In the bottle type, the neck and shoulders, the body, and the bottom are integrally molded by forming the slanted shoulder and the small-diameter cylindrical mouth and neck. Manufactures intermediate molded products. In the method of the present embodiment, as shown in FIG. 2 (A), in this neck-in processing step, the diameter reduction processing is performed at least once with respect to a predetermined range from the opening end of the mouth and neck. In addition, the neck portion 2 of the bottle-shaped intermediate molded product 10 is formed in two steps (a small diameter upper step portion m1 and a large diameter lower step portion m2).

  Next, a screw is formed on the peripheral wall (scheduled portion of the neck) of the mouth-and-neck portion 2 by using a screw processing tool with an inner roll and an outer roll in a screw forming process for the bottle-shaped intermediate molded product. is doing. In the method of the present embodiment, as shown in FIG. 2A, in the two-stage mouth and neck portion 2 having a small-diameter upper portion m1 and a large-diameter lower portion m2, the lower portion of the upper portion m1 is threaded. A threaded portion 2c is formed in the mouth-and-neck portion 2 as shown in FIG.

  After the screw portion 2c is formed in the mouth and neck portion 2 in this manner, the diameter of the short cylindrical portion (the upper portion of the upper portion m1) above the screw portion 2c of the mouth and neck portion 2 is further reduced by several times of diameter reduction processing. As shown in FIG. 2C, the inclined portion 2b whose diameter is reduced upward is formed above the screw portion 2c, and the small diameter short cylinder whose diameter is reduced above the inclined portion 2b. Is formed into a portion (curled processing planned portion) n1. Then, after performing trimming processing for trimming the upper end of the small-diameter short cylindrical portion n1 of the neck and neck portion 2, by curling the small-diameter short cylindrical portion n1 with a curl forming device, as shown in FIG. The bottle-type can 1 has an outer curled portion 2a formed on the opening end of the mouth / neck portion 2 above the inclined portion 2d.

  By the way, in the manufacturing process of the bottle-shaped can as described above, in the method of the present embodiment, in the screw forming process, a screw processing tool with an inner roll and an outer roll is used, and the peripheral wall of the mouth and neck (scheduled thread processing) Part), the inner diameter d1 of the part to be threaded of the mouth and neck is 37 mm or less (for example, 28 mm), whereas in a threading tool using an inner roll and an outer roll, The ratio (d1 / d2) of the inner diameter d1 of the threaded portion of the mouth and neck to the outer diameter d2 of the inner roll is within the range of 1.0 to 1.4 (preferably 1.05 to 1.15. An inner roll having an outer diameter close to the inner diameter of the thread processing scheduled portion is used.

  That is, in the screw forming step, as shown in FIG. 3, an inner roll 21 to be inserted into the mouth and neck portion 2 and an outer roll 22 to be disposed on the outer peripheral side of the mouth and neck portion 2 are used. The inner roll 21 and the outer roll 22 are pressed against the threaded portion of the peripheral wall of the peripheral wall from the inner surface side and the outer surface side, respectively. The inner roll 21 connected to the drive source is driven to revolve along the inner peripheral surface of the mouth-and-neck portion 2 while rotating, and the inner roll 21 is synchronized with the inner roll 21 in a state where the portion to be processed is sandwiched. The outer roll 22 supported rotatably is revolved along the outer peripheral surface of the mouth-and-neck portion 2 while rotating, so that the rolls 21 and 22 do not rotate so as to have substantially the same peripheral speed. Be to cooperate so as to al revolution, and roll forming the screw on the peripheral wall of the neck 2 (thread planned processing unit).

  In addition, when the peripheral wall (screw processing plan part) of a neck and neck part is pinched | interposed between an inner roll and an outer roll, it does not specifically limit about the moving direction of an inner roll and an outer roll. That is, as a first method, there is a method in which the outer roll is not moved in the radial direction, and the inner roll is moved in the radial direction (outer roll side). On the contrary, as the second method, There is a method of moving the outer roll toward the inner side (inner roll side) in the radial direction without moving the inner roll in the radial direction. Further, as a third method, the inner roll is moved outward in the radial direction. There are methods for moving the rolls inward in the radial direction, any of which may be adopted.

  In the case of adopting the first method, since the inner roll moves outward and the screw is formed, the inner diameter after screw forming becomes relatively large, and the inner roll can be easily pulled out. The ratio (d1 / d2) between the inner diameter d1 of the planned machining portion and the outer diameter d2 of the inner roll is 1.0 or close to 1.0 (the outer diameter d2 of the inner roll is almost the same as the inner diameter d1 of the planned machining portion). In some cases, in other methods, in order to avoid deformation due to contact between the inner surface of the formed screw portion and the inner roll, it is necessary to pull out while rotating the inner roll in the direction of pulling out from the formed screw portion. However, in this method, the inner roll can be easily extracted without the necessity.

  When the third method is employed, damage such as cracking or peeling is less likely to occur in the coating film formed on the surface of the mouth and neck as compared with other methods. In other words, when one of the rolls is pushed in unilaterally, the surface on the pushed side is subjected to a large deformation, whereas by placing both rolls close to each other, This is because deformation on the surface (inner surface and outer surface) is alleviated.

  In any case, in the screw forming process as described above, the outer diameter d2 of the inner roll is smaller than the inner diameter d1 of the threaded planned portion of the mouth and neck, as shown in FIG. The inner roll 21 that has been in contact with the mouth and neck part (scheduled part to be threaded) 2 at the point A at the start of screw processing is rotated once with respect to the mouth and neck part 2 as shown in FIG. Then, the entire circumference of the mouth-and-neck portion 2 did not revolve, and further rotated, and as shown in FIG. 4C, at the end of screw processing, the rotation progressed more than the contact point A at the start. At the point B, the processing returns to the processing start position of the mouth-and-neck portion (thread processing scheduled portion) 2.

  And since the screw | thread of the same pitch as the screw formed in the screw process scheduled part of the mouth-and-neck part 2 is formed in the outer peripheral surface of the inner roll 21, it is screwed in all the circumferences of the screw-process scheduled part of the mouth and neck part 2. When the screw processing is completed and the inner roll 21 is rotated, the screw pitch is shifted to the screw pitch (the distance between the screw thread and the screw thread or the center line in the width direction of the screw groove and the screw groove). Will occur. That is, as shown in FIG. 5, the screw is formed in the state indicated by the solid line at the start of the screw processing, and the screw is formed in the state indicated by the broken line at the end of the screw processing. It will be.

  As a result, the greater the difference between the inner diameter d1 of the threaded portion of the mouth and neck portion and the outer diameter d2 of the inner roll, the greater the deviation in the pitch of the screw. Since the inner roll and the outer roll form a screw by sandwiching the screw portion already formed at the start of screw molding, the shape of the screw portion becomes distorted at that portion, The thread groove is not formed well, and the function as a screw is impaired. As a result, the opening and sealing properties are adversely affected.

  In order to deal with such a problem, in the method of the present embodiment, as described above, the ratio (d1 / d2) between the inner diameter d1 of the threaded portion of the mouth and neck portion and the outer diameter d2 of the inner roll is 1. Within a range of 0.0 to 1.4 (preferably within a range of 1.05 to 1.15). Thereby, in the screw forming process, it is possible to suppress the deviation of the pitch of the screw at the time of screw processing within an allowable range, and as a result, it is possible to suppress the distortion of the screw portion within an allowable range, Openability and sealing properties can be improved.

  In addition, when the ratio (d1 / d2) between the inner diameter d1 of the planned threading portion of the neck and neck and the outer diameter d2 of the inner roll is less than 1.0 (that is, the inner roll is smaller than the inner diameter d1 of the planned threading portion). Naturally, the inner roll cannot be inserted into the portion to be threaded, so screwing is impossible. On the other hand, at 1.4 or more, the screw pitch is shifted. When it becomes larger than the allowable range, the sealing performance and the opening performance are deteriorated.

To specifically verify the above points, the thread pitch is 8 threads per inch, that is, the thread pitch interval (the distance between the thread and the center line of each thread) is 3.175 mm. A plurality of inner rolls having different outer diameters d2 for each of the bottle-shaped intermediate molded products having inner diameters d1 of the threaded portions of the neck and neck of 37 mm, 33 mm, and 26 mm (experimental example) Experiments were performed so that each of the screws was processed according to 1 to 8). And about each experiment example, while checking the shaping | molding state of the screw part visually, the state of attachment or detachment of the cap was tested.
In this experiment, the outer roll is not moved in the radial direction when the peripheral wall (scheduled portion of the neck) of the mouth and neck is sandwiched between the inner roll and the outer roll. It is moved toward the roll side.

The results of the above experiment are shown in Table 1 below.
The symbols in the table are as follows.
d1: Indicates the inner diameter of the threaded portion of the mouth and neck.
d2: Indicates the outer diameter of the inner roll.
d3: indicates the outer diameter of the threaded portion.
d4: Indicates the inner diameter of the small-diameter short cylindrical portion (curled processing scheduled portion).
X: Indicates a state in which the displacement of the pitch of the screw portion is large and the cap cannot be attached or detached.
○: Although the deviation of the pitch of the screw part can be visually confirmed, it indicates that there is no problem in attaching and detaching the cap.
A: The gap in the pitch of the screw part is hardly visually confirmed, and the cap can be attached and detached satisfactorily.

  It can also be seen from the results of the experiment shown in Table 1 above (d1 / d2 is not in the present experimental example because it is impossible to perform threading when it is 1.00). Thus, when d1 / d2 is within the range of 1.00 to 1.40, there was no problem in the attachment / detachment of the cap and the sealing performance. In particular, in the range of 1.05 to 1.15, almost no pitch deviation was visually confirmed, and both the cap attachment and detachment and the sealing performance were good. On the other hand, when d1 / d2 is 1.40 or more (1.45), there is a large shift in pitch at the formed screw portion, and the cap cannot be attached or detached satisfactorily.

  In addition, after forming the screw part in the mouth and neck part of the bottle-shaped intermediate molded product as described above, the neck-in process is further repeated on the short cylindrical part above the screw part of the mouth and neck part. By reducing the diameter, as shown in FIG. 2C, an inclined portion 2b is formed above the screw portion 2c, and a small-diameter short cylindrical portion (curled portion to be curled) whose diameter is reduced above the inclined portion 2b. ) N1 is formed so that the ratio (d3 / d4) between the outer diameter d3 of the screw portion 2 and the inner diameter d4 of the small-diameter short cylindrical portion n1 after the diameter reduction processing is 1.1 or more.

  Then, after performing trimming processing for trimming the upper end of the small-diameter short cylindrical portion (curled processing portion) n1, the curling processing is performed to curl the small-diameter short cylindrical portion n1 to the outside, and the screw of the mouth-and-neck portion 2 As shown in FIG. 1, by performing bead processing (processing to form an annular concave portion and forming an annular convex portion on the upper side thereof) at a portion below the portion 2 c to project a part thereof inward. The curl part 2a, the annular convex part 2d, and the annular concave part 2e are formed in the mouth and neck part 2 to complete the manufacturing process of the bottle-type can.

  According to the bottle-shaped can manufacturing method of the present embodiment as described above, when manufacturing a bottle-shaped can in which the mouth-and-neck portion, the shoulder portion, the trunk portion, and the bottom portion are integrally formed, an intermediate molded product of the bottle shape After forming the threaded portion by subjecting the threaded portion of the mouth and neck to a threaded portion, the diameter of the upper portion is reduced to form a small-diameter short cylindrical portion that becomes the curled portion. Therefore, compared to the reverse case, an inner roll having a large outer diameter can be used as an inner roll to be inserted into the neck of the mouth as a screw processing tool during screw processing. As a result, even when manufacturing a bottle-shaped can having a small diameter at the mouth-and-neck portion (for example, a bottle-shaped can in which the inner diameter of the threaded portion of the mouth-and-neck portion is 37 mm or less), it is suitable. An inner roll having an outer diameter can be easily prepared.

  In the threading process, the ratio (d1 / d2) between the inner diameter d1 of the threaded portion of the mouth and neck and the outer diameter d2 of the inner roll 21 is in the range of 1.0 to 1.4. In addition, by using an inner roll with a relatively large outer diameter (a size close to the inner diameter of the threaded portion), the difference between the inner diameter of the threaded portion and the outer diameter of the inner roll is reduced. , The ratio of the range of screws that can be formed by one rotation of the inner roll in the circumferential direction of the thread processing scheduled portion can be increased, and the roll is slipped by adjusting the rotation speed of the inner roll and the outer roll It is possible to suppress the displacement of the screw pitch in the circumferential direction of the mouth-neck portion by merely synchronizing the outer roll with the rotation of the inner roll. As a result, the threaded portion can be formed satisfactorily without almost distorting the threaded portion, the complicated rotation control of each roll is not required, and the can surface is coated with the threaded portion by friction due to slip. There is no damage to the membrane.

  In addition, it is possible to perform the screw processing satisfactorily by using the inner roll having such a large outer diameter, and when the upper diameter of the processed screw portion is reduced, the outer diameter d3 of the screw portion is reduced. Since the upper part of the screw part is sufficiently reduced in diameter so that the ratio (d3 / d4) to the inner diameter d4 of the small-diameter short cylindrical part after diameter processing is 1.1 or more, the final shape is formed. When the cap is attached to the mouth and neck, it is not difficult to attach and detach the cap due to the interference between the curled portion formed above the screw portion and the screw portion of the cap.

  In addition, since the curled part is formed after the screw part is formed in the mouth and neck part, the lateral pressing force applied to the mouth and neck part from the screw processing tool (inner roll or outer roll) during screw processing. Even if the roundness near the upper end of the mouth and neck is reduced by the above, the roundness of the curled portion will be corrected by the curling tool inserted inside the mouth and neck during the subsequent curling. As a result, by increasing the roundness of the curled portion, it is possible to improve the sealing performance between the sealing member of the cap and the curled portion that is attached to the mouth and neck portion.

  Furthermore, in the method of the present embodiment, when the diameter of the opening end side of the body of the bottomed cylindrical can is reduced to form an inclined shoulder and a small diameter cylindrical mouth and neck, the opening of the mouth and neck The neck and neck parts are formed in two steps by applying a diameter reduction process at least once to a predetermined range from the end, and a screw part is formed in the lower part of the upper part, so that a metal pilfer When forming the annular convex part for fixing the rupture band of the proof cap below the screw part (lower part), the molding (the part directly below the part where the annular convex part is to be provided is inward by the groove forming roll. By pressing and molding into an annular recess, as a result, it becomes easy to perform molding such that the upper portion is an annular projection.

  As mentioned above, although the Example of the manufacturing method of the bottle-shaped can of this invention was described, the method of this invention is not limited to the above Examples, It can change suitably, for example, In the above embodiment, when the opening end side of the body portion of the bottomed cylindrical can is formed into an inclined shoulder portion and a small-diameter cylindrical mouth-and-neck portion to form a bottle-shaped intermediate molded product, The neck and neck are formed in two stages by performing diameter reduction processing at least once on a predetermined range from the opening end of the mouth, but the diameter of the mouth and neck decreases from the bottom upward. In this case, after forming the threaded portion, the number of times of diameter reduction processing for the short cylindrical portion above the threaded portion can be reduced. By reducing the diameter, the load on the screw part can be reduced and the screw part can be shaped. It is possible to reduce the possibility that the threaded portion is deformed by diameter reduction of the neck of after.

  When the neck and neck of the bottle-shaped intermediate molded product is formed in three stages, the middle part thereof becomes a threaded part to be subjected to screw machining, and the upper part is reduced in diameter so that the inclined part and the small diameter short part are formed. It becomes a cylindrical part (curled part to be processed), but the inner diameter of the upper part is the middle part, which is the planned part for screw processing, when it is formed into a bottle-shaped intermediate molded product (before being threaded). The inner roll needs to be of a size that is slightly smaller than the inner diameter of the portion and that can pass an inner roll having an outer diameter within the range defined in the present invention. Further, when the mouth-and-neck portion of the bottle-shaped intermediate molded product is formed in three stages, the ratio (d1 / d2) between the inner diameter d1 of the portion to be threaded of the mouth-and-neck portion and the outer diameter d2 of the inner roll is: Although it is 1.4 or less, in 1.0 it becomes impossible to insert the inner roll into the mouth and neck through the upper portion, so it is necessary to be larger than 1.0.

The side view which shows an example of the bottle-shaped can manufactured by the method of this invention. Regarding the method of the present invention, (A) a bottle-shaped intermediate molded product formed from a bottomed cylindrical can, (B) a state in which a screw portion is formed on the mouth and neck, and (C) the mouth and neck The side view which shows the state by which diameter reduction processing was carried out above the thread part, respectively. Cross-sectional explanatory drawing which shows the arrangement | positioning state of the inner roll and outer roll at the time of giving a screw process to the screw process plan part of a mouth neck. The cross-sectional explanatory drawing which shows each state (A), (B), (C) from the time of a process start to the time of a process end about the thread process given to the thread process scheduled part of a mouth neck. The longitudinal cross-sectional explanatory drawing shown about the shift | offset | difference of the screw pitch which arises at the time of the screw processing by an inner roll and an outer roll.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bottle type can 2 Neck part 2a Curl part 2b Inclined part 2c Screw part 2d Annular convex part 2e Annular recessed part 3 Shoulder part 4 Body part 5 Bottom part 10 Bottle type intermediate molded product 21 Inner roll 22 Outer roll d1 Inner diameter of the threaded portion d2 Outer diameter of the inner roll d3 Outer diameter of the screw portion d4 Inner diameter of the small-diameter short cylindrical portion (curled portion)

Claims (3)

  At least drawing and ironing to form a bottomed cylindrical can with a bottom and body integrally formed from a thin metal plate, and then reduce the diameter of the open end of the thinned cylindrical body After forming a bottle-shaped intermediate molded product by molding it into an inclined shoulder and a small diameter cylindrical mouth and neck, the curled part of the opening end and the threaded part of the peripheral wall are made to the mouth and neck. In a manufacturing method of a bottle-type can that forms a mouth-and-neck part into a final shape by molding, when forming the mouth-and-neck part of a bottle-shaped intermediate molded product into a final shape, a screw with an inner roll and an outer roll After processing and forming the threaded portion of the mouth and neck into a threaded portion, the small cylindrical portion is reduced in diameter after at least once reducing the diameter of the short cylindrical portion above it. The part is curled and molded into the outer curled part. When processing the inner roll, the ratio (d1 / d2) of the inner diameter d1 of the threaded portion of the neck and neck to the outer diameter d2 of the inner roll is in the range of 1.0 to 1.4. A method for producing a bottle-shaped can characterized by being used.   For a bottle-shaped intermediate molded product whose inner diameter of the threaded portion of the mouth and neck is 37 mm or less, after the portion of the threaded portion is formed into a screw portion, the diameter of the upper portion of the formed screw portion is reduced. In this case, the diameter reduction processing is performed so that the ratio (d3 / d4) of the outer diameter d3 of the screw portion and the inner diameter d4 of the small-diameter short cylindrical portion after the diameter reduction processing becomes 1.1 or more. Item 2. A method for producing a bottle-shaped can according to Item 1.   When the diameter of the opening end of the body of the bottomed cylindrical can is reduced and formed into an inclined shoulder and a small diameter cylindrical mouth and neck, a bottle-shaped intermediate product is formed. At least one diameter reduction process has been applied to a predetermined range from the opening end of the mouth and neck, and at the time of subsequent screw processing, a screw process is applied to the lower part of the reduced diameter part of the mouth and neck. The method for manufacturing a bottle-shaped can according to claim 1 or 2, wherein a threaded portion is formed.

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