JP2011092960A - Method for manufacturing metal container and inner molding roll thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a metal container preventing or reducing convex deformation generated at the bead and/or the vicinity of the neck of the side wall of the shell of the metal container and preventing the depression and the shaving of the coating film and printing film of the side wall of the shell during collision and contact of the containers, and also to provide the inner molding roll thereof. <P>SOLUTION: The inner molding roll 40 having an annular recess 41 at a side surface and an outer forming roll having an annular protrusion at the side surface are respectively arranged at the inner side and the outer side of the shell of the metal container. The side wall directed from the annular recess start point S of the inner molding roll 40 to the annular recess 41 of the inner molding roll 40 has an inconstant curvature and has a roundness formed of a smoothly increasing continuous curved line. The bead and/or the neck is formed at the shell of the metal container by the inner molding roll 40 and the outer molding roll. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a metal container having a bead portion and / or a neck portion on a body side wall and an inner forming roll thereof, in particular, convex distortion and deformation generated in the vicinity of the bead portion and / or neck portion of the body side wall. It is an object of the present invention to provide a method for manufacturing a metal container and an inner forming roll thereof, which are less likely to cause dents and coating film / printed film scraping on the barrel side wall against collision / contact between metal containers.

Conventionally, in order to increase the strength of the barrel when decompressing a metal container and reduce the material used by thinning the metal material, the barrel has been subjected to deep bead processing with a relatively large height and width. Yes. (For example, see Patent Document 1.)
In addition, in a powdered milk can or the like, an inner bulging bead portion is provided in the can body for the purpose of attaching a scraping member for taking a fixed amount of milk powder into the can. (For example, see Patent Document 2.)
Furthermore, a neck-in process for reducing the diameter of the body portion is performed at the end portion of the body portion of the metal container for the purpose of reducing the amount of lid material wound around the end portion. (For example, see Patent Document 3)
On the other hand, in large-diameter milk cans, which are metal containers that contain powdered milk, etc., the bead processing in which the barrel side wall is recessed radially inward in order to increase the strength of the can barrel, or the vicinity of the can mouth inward in the radial direction Recessed neck processing is applied.
The weight of powdered milk cans filled with powdered milk is heavy, so it is not easy to hold and carry. In order to solve such problems, a deep bead portion having a large height and width is formed near the end portion of the body portion to improve grip and handling properties.
In addition, with this configuration, the canopy before opening is protected, or it is easy to fix by hand when removing the plastic lid that seals the metal container after opening, and when the milk powder is taken out with a spoon, the can body It also has the advantage of being easy to tilt.
FIG. 11 is an explanatory view showing bead processing for a can body of a metal can which is a conventional metal container. FIG. 11 (a) shows a state before processing, and FIG. 11 (b) shows a state after processing.
FIG. 12 is an enlarged view of the vicinity of the bead processing portion of the outer forming roll 50 and the inner forming roll 40 ′ during bead processing.
In the following, the bead processing will be described with reference to this drawing, but the same tendency occurs also in the processing of the neck portion.
As shown in FIGS. 11 and 12, in order to process the bead portion after forming the cylindrical can body, the inner forming roll 40 ′ located inside the can body holds the can body and is located outside the can body. The annular convex portion 51 of the outer molding roll 50 is molded by pushing the bead-corresponding portion of the can body into the annular concave portion 41 ′ of the inner molding roll 40 ′ while rotating radially inward.
And by pushing the annular convex part 51 of the said outside shaping | molding roll 50 from a can body outer surface, a bead part is processed, but as shown in detail in FIG. 12, from the cyclic | annular recessed part start point of this inside shaping | molding roll 40 '. The shape of the side wall 41′b toward the bottom surface portion 41′a of the annular recess is configured based on an R portion formed of a curve with a constant curvature.
In such metal processing, a springback occurs after the processing, so that the pressing amount of the outer forming roll 50 is set larger than the depth of the bead portion formed in the can body. Further, when the bead processing is performed, bending stress and tensile stress are excessively concentrated on the can body portion (that is, the annular recess starting point) contacting the maximum diameter portion of the R portion of the annular recess 41 ′ of the inner forming roll 40 ′. As a result, the plate thickness of the can body in this portion is reduced, and the bending angle is acute. For this reason, when the outer forming roll 50 is separated to the outside after the processing is finished, the can body is in contact with the vicinity of the maximum diameter portion of the R portion by the metal spring back, and the can body portion protrudes outward (hereinafter, “ Convex deformation "). In particular, when bead processing (big bead portion processing) is performed to increase the depth of the bead portion, this tendency appears remarkably.
When such a convex deformation occurs, when the empty can or the contents-filled can is transported, when the cans collide with each other or the transport guide, the convex deformed portion is easily dented or rubbed. However, although not shown, such a problem is also the case when the height, width, and depth of the neck portion are large, and the appearance In addition, the convex deformation may occur even if it is not conspicuous.

JP-A-55-134049 Japanese Utility Model Publication No. 62-168324 Japanese Patent Laid-Open No. 48-30582

  The present invention has been made in view of the problems in the conventional method for manufacturing a metal container, and the object of the present invention occurs in the vicinity of the bead portion and / or the neck portion of the body side wall of the metal container. Providing a metal container manufacturing method and an inner forming roll thereof that prevent or reduce convex deformation and prevent dents in the body side wall and coating film / printed film scraping during collision / contact between containers. is there.

As an invention for achieving the above object,
An inner forming roll and an outer forming roll are rotatably arranged inside and outside the body portion of the metal container, and the outer forming roll is pushed into the inner forming roll to bead the body portion of the metal container. In the method of manufacturing a metal container for forming a neck portion and / or a neck portion, the inner forming roll has an annular recess formed on a side surface, which includes a bottom surface portion and both side walls corresponding to the bead portion or the neck portion of the body portion. The corner R portion of the side wall corresponding to at least the maximum diameter is an R portion formed of a curve that smoothly increases from the annular recess starting point corresponding to the maximum diameter toward the boundary point with the side wall. By doing so, the convex deformation in the vicinity of the processing portion of the body portion contacting the vicinity of the annular recess start point of the inner forming roll is reduced. The method of manufacturing is provided.

In the method for producing a metal container of the present invention,
1. A part or all of the curve is configured based on a clothoid curve,
2. The bead portion of the metal container is a big bead having a depth of 2 mm or more;
3. The convex deformation in the vicinity of the processing portion of the body portion that contacts the vicinity of the annular recessed portion starting point corresponding to the maximum diameter of the annular recessed portion of the inner forming roll is suppressed to 0.15 mm or less from the protruding amount from the can body flat portion. It is preferable to do so.

As a second invention for achieving the above object,
An inner forming roll for forming a bead portion and / or a neck portion in a body portion of a metal container in cooperation with the outer forming roll;
In an inner forming roll having one or more annular recesses recessed inward in the radial direction on the side, at least the corner R portion of the side wall corresponding to the maximum diameter of the annular recess, the annular recess start point corresponding to the maximum diameter The inner forming roll is characterized in that the curvature toward the boundary point with the side wall is not constant, but is an R portion formed of a smoothly increasing curve.

In the inner forming roll of the second invention,
1. A part or all of the curve is configured based on a similar clothoid curve obtained by similar enlargement conversion of a part of the clothoid curve,
2. The annular recess starting point is the origin of the clothoid curve;
3. The starting point of the annular recess is the origin of the clothoid curve, and the boundary point is an inflection point in the first quadrant or the third quadrant where the sign of the change amount of X with respect to the parameter T in the clothoid curve changes from positive to negative. It is preferable that the point corresponds to.

  According to the metal container manufacturing method and the inner forming roll of the present invention, in processing of the bead portion and / or neck portion, particularly in the processing having a large depth, it corresponds to the maximum diameter of the annular recess of the inner forming roll. Bending and pulling work in which stress is not excessively concentrated can be performed at the processing part of the body part in contact with the vicinity of the starting point of the annular recess, and as a result, convex deformation in the vicinity of the processing part of the body part of the metal container is prevented or As a result, dents in the can body and scraping of the coating film / printed film when the cans collide and contact each other can be suitably prevented.

It is explanatory drawing which shows metal containers. It is the elements on larger scale of FIG. It is explanatory drawing of the inner side forming roll used for the manufacturing method of the metal container of this invention. It is explanatory drawing which shows a clothoid curve. It is a flowchart which shows the design procedure which applies a clothoid curve to the internal angle R part of the annular recessed part of an inner side forming roll. It is explanatory drawing which shows the state which plotted clothoid curve C1, the cyclic | annular recessed part start point S, and the boundary point E. FIG. It is explanatory drawing which shows the similar clothoid curve C'1. It is explanatory drawing which shows the coordinate transformation of the similar clothoid curve C'1. It is a plate | board thickness figure of the big bead part vicinity of this invention can and a conventional can. It is explanatory drawing which shows a rolling impact test method. It is explanatory drawing which shows the bead process with respect to the conventional can body. It is the elements on larger scale of FIG.

  In the following, the present invention is applied to bead processing and will be described in more detail with reference to embodiments shown in the drawings. The application of the present invention is not limited to bead processing, but can be similarly applied to neck processing or the like processed into an annular recess.

FIG. 1 is an explanatory view showing a metal can 100 having a big bead portion 13 obtained by the method for manufacturing a metal container of the present invention, and FIG. 2 is a partially enlarged view thereof.
As described above, a cylindrical outer plate roll 50 (male) disposed on the outer side of the can body is pushed into the cylinder in the radial direction by rounding the metal plate and welding the end portion and the end portion of the cylinder. At the same time, as the inner forming roll 40 (female mold) disposed inside the can body and the body portion 10 receive the outer forming roll while rotating, the body portion 10 serves as an annular recess recessed radially inward. A big bead portion 13 having a large depth is formed. In the present embodiment, a small bead is provided above the big bead portion 13 in the drawing, and the can body diameter on the small bead side is smaller when the can body diameters at the top and bottom of the big bead portion 13 are compared.

  The forming of the bead portion will be described in more detail. After forming the metal plate into a cylinder, the neck and flange portions are respectively formed at both ends of the can body. Next, the both ends of the can body are fixed by being sandwiched by chucks, and the can body is rotated by rotating the chuck. Next, the inner forming roll 40 disposed inside the can body is moved to a predetermined position in the can body radial direction while being rotated in synchronization with the rotation of the can body. In this state, by pressing the free-rotating outer forming roll 50 inward in the can body radial direction, the outer forming roll 50 rotates in synchronization with the can body due to frictional resistance and deformation resistance with the can body, and the body portion 10 A bead part is formed.

Generally, in the vicinity of the big bead portion 13 of the metal can 100, when the depth of the bead is increased, the convex deformation generated radially outward tends to increase. In particular, in the present embodiment, since the upper part of the big bead 13 has a smaller diameter than the lower part, the lower outer diameter D1 is larger than the can body outer diameter D2.
However, in the metal can 100 obtained by the metal container manufacturing method of the present invention, since the big bead portion 13 is processed by the inner forming roll 40 described later, the convex deformation near the lower portion of the big bead portion 13 is shown in FIG. As shown, it can be prevented or reduced, and the amount of protrusion relative to the outer diameter of the can body can be made much smaller than the amount of protrusion of the conventional metal can shown by the broken line in FIG.

FIG. 3 is an explanatory view showing an inner forming roll 40 used in the method for manufacturing a metal container of the present invention. FIG. 3 (a) shows a cross section thereof, and FIG. 3 (b) shows an enlargement of the B portion thereof.
The inner forming roll 40 has an annular recess 41 related to forming the big bead portion 13.
For the corner R portion corresponding to the maximum diameter of the inner forming roll 40, the curvature from the annular recess starting point S corresponding to the maximum diameter toward the side wall 41b of the annular recess 41 is not constant but smoothly increases and continues. The R portion is made of, and the outer shape of the R portion is configured based on a clothoid curve. More specifically, the shape of the R portion from the annular recess starting point S corresponding to the maximum diameter of the annular recess 41 to the boundary point E between the side wall 41b of the annular recess 41 and the R portion is defined as the annular shape. It is preferable that the curvature at the recess starting point S is very small and the curvature gradually and gradually increases from the annular recess starting point S to the boundary point E. The boundary point E is a portion where the R portion substantially coincides with the straight portion of the side wall 41b, and the first inflection point P _{1 at which} the sign of the change amount of X with respect to the parameter T in the clothoid curve changes from positive to negative. , P ₋₁ (see FIG. 4). Accordingly, in the present embodiment, as an example of the curve of the R portion, a similar clothoid curve obtained by converting the above-mentioned annular recess starting point S to the origin of the clothoid curve and a portion of the clothoid curve (origin → P ₁ or P ₋₁ ) is converted. Has been applied.
When bead processing is performed using an outer forming roll (not shown), it is possible to perform processing in which bending stress and tensile stress are not excessively concentrated on the can body part contacting the annular recess starting point S of the inner forming roll 40. It becomes.
As a result, it becomes possible to prevent the convex deformation of the big bead portion 13 or its vicinity due to bead processing, thereby increasing the contact area when adjacent cans collide and contact each other, and impact is preferable. To improve the impact resistance of the can. As a result, even when the metal can 100 is placed in a packing or transporting state where the cans are in close contact with each other or collide with each other, the coating film / printed film on the outer surface of the metal can, such as scraping or deformation Damage is prevented.

  In the present embodiment, the boundary point E is the boundary point of the R portion that substantially coincides with the straight portion of the side wall 41b in the annular recess 41 of the inner forming roll 40, but is not limited to this boundary point. Absent. A range in which at least the can body being processed contacts the side wall 41b of the inner forming roll 40 or the vicinity thereof may be a clothoid curve. Similarly, the annular recess starting point S (starting point of the R portion) is preferably coincident with the origin of the clothoid curve, but may be in the vicinity of the origin.

FIG. 5 is a flowchart showing a design procedure for applying the clothoid curve to the inner corner R portion of the annular recess 41 of the inner forming roll 40.
First, in step S1, it is determined which section of the clothoid curve is to be used. The clothoid curve has a characteristic that the curvature κ increases smoothly with the increase of the parameter T in the entire section. Here, the inner angle R portion of the annular recess 41 is configured using the clothoid curve of C1 (O → P ₁ ) in FIG.

In step S2, the annular recess starting point S and the boundary point E of the inner corner R of the annular recess 41 are made to correspond to the start point and end point of the clothoid curve.
For example, the annular recess starting point S corresponding to the maximum diameter in FIG. 3B is made to correspond to the origin of the clothoid curve, and the boundary point E that becomes the boundary with the side wall 41b is made to correspond to the first inflection point P ₁ of the clothoid curve. Let

In step S3, the annular recess starting point S and the boundary point E of the inner corner R portion of the annular recess 41 are plotted in the coordinate system of the clothoid curve.
Returning to FIG. 3B again, the actual coordinate system (real coordinate system) and the clothoid coordinate system are in a mirror-surface relationship. That is, the real coordinate system is a left-handed system, but the clothoid coordinate system is a right-handed system. Therefore, the coordinates of the boundary point E when the annular recess starting point S is the origin are, for example, the point (−4.10, 2.30) in the real coordinate system, but the point E (4.10, 2.30) in the clothoid coordinate system. Therefore, when displaying a point in the clothoid coordinate system in the real coordinate system, it is necessary to invert the X coordinate. FIG. 6 shows a state in which the clothoid curve C1, the annular recess starting point S, and the boundary point E are plotted in the clothoid coordinate system. Note that the Y coordinate of the boundary point E may be given in advance, but here the Y coordinate of the boundary point E is not given in advance because the similarity enlargement coefficient in step S4 is unified (only k _X ). It was to be. Y coordinate of the boundary point E is that calculated by multiplying the similarity enlargement factor k _X in the X direction to the Y-coordinate of P ₁ in step S4.

In step S4, as the end point P ₁ of the clothoid curve C1 coincides with the boundary point E, to similar enlargement of the clothoid curve C1.
Since the X coordinate of P ₁ is 0.98 and the X coordinate of the boundary point E is 4.10, for example, the X-direction similarity enlargement factor k _X is k _X = 4.10 / 0.98 = 4. 18 times. On the other hand, since the Y coordinate of P ₁ is 0.55, the Y coordinate of the boundary point E becomes 2.30, which is 4.18 times 0.55. Therefore, the plot data of the clothoid curve C1 by multiplying the k _X to X and Y coordinates of (X (T), Y ( T)), similar enlargement clothoid the endpoint P ₁ of the clothoid curve matches the boundary point E A curve C′1 (O → P ₁ ) can be created. Therefore, each plot data (X ′ (T), Y ′ (T)) of the similar enlarged clothoid curve C′1 is (X ′ (T), Y ′ (T)) = (k _X · X (T) , k _X · Y (T)).
As for the similarity enlargement factor k _X, rather than set uniformly in the X direction and the Y direction, it may be set individually for each plot data.

In step S5, the actual coordinate system is converted.
As described above, the clothoid coordinate system is a right-handed system, and the actual coordinate system is a left-handed system. Therefore, similar clothoid curve C'1 in the real coordinate system (O → P _1), the clothoid in FIG clothoid curve C'1 the (O → P ₁₎ folded in the Y-axis of FIG. 8 (a) 8 (b) Curve C′1 (O → P ₁ ) curve.

A tin plate having a plate thickness of 0.26 mm was rolled and welded end to end to form a cylindrical can body.
To this can body, using the inner forming roll (the present invention can) with the aforementioned R portion as a clothoid curve and the inner forming roll (conventional can) with the R portion having a curvature radius of 4.75 mm, bead processing is performed, The canopy was double-rolled to prepare a bead processing can for a milk powder can having a content of 1000 g with a bead width of 15 mm and a depth of 4.0 mm.
FIG. 9 shows measured values of the metal plate thickness in the vicinity of the big bead lower annular recess starting point of the obtained bead processing can. The horizontal axis shows the length from the top. The position of the bead in these bead processing cans is 20 to 35 mm in the height direction from the top surface, and the position of 35 mm is a position in contact with the annular recess starting point of the inner forming roll.
In both the can of the present invention and the conventional can, the plate thickness in the vicinity of the big bead portion is reduced by the bead processing with respect to the original plate thickness of 0.260 mm before processing. The degree of the reduction is particularly large at the annular concave portion starting point contact portion of the inner forming roll. When the present invention can and the conventional can are compared, the present invention can has a larger thickness in the vicinity of the big bead portion. In particular, the plate thickness of the annular recess starting point contact portion is extremely small in the conventional can, whereas the decrease in the can of the present invention is relatively small. From these, it can be seen that the big bead processing method of the present invention is considerably gentler to material deformation than the conventional processing method. As a result, the amount of protrusion from the flat portion of the can body in the vicinity of the big bead (in the vicinity of the annular recess starting point contact portion) of the can of the present invention is 0.10 mm, and the inner forming roll having the corner R portion of the conventional uniform curvature. Compared with the case where it was formed by 0.18 mm, it is much smaller.

This bead-processed can was filled with 1 kg of milk powder, the bottom lid was double-tightened and sealed, and then the rolling impact test shown in FIG. 10 was performed. The dent of the can in each rolling distance L was observed, and the dent length and the dent depth were measured. After the test, about the dent part of the can, the dent length was measured with a scale by applying light to the dent part, and the dent depth was measured with a depth gauge at the deepest part of the dent part.
In the rolling impact test, as shown in FIG. 10, the rolling can is rolled to collide with the standby can, and the rolling distance L is set to 200 mm, 400 mm, 600 mm, and 800 mm. At any level, the tilt angle (θ) was set to 10 degrees. The test was performed 4 times for each level.
The dent length and the dent depth are both average values of the standby can and the rolling can in four tests, and the dent region is a product of the dent length and the dent depth. The average value was calculated assuming that the number of cans without dents was zero. The test results are shown in Table 1.

  As a result of this experiment, the metal can having a bead manufactured by the method for manufacturing a metal container according to the present invention is prevented from the convex deformation of the big bead portion or its vicinity caused by bead processing, and adjacent cans are It can be seen that the contact area at the time of collision / contact increases, the impact is suitably dispersed, and the impact resistance of the can is improved. As a result, even when the cans are in close contact with each other or are placed in a packing or transporting state where the cans collide with each other, damage to the outer surface of the metal can, such as coating film or printed film scraping or deformation, is prevented. I understand that

  The present invention is made of all metal having a bead portion and / or a neck portion formed on a side wall of a body portion by an outer forming roll disposed outside the can body and an inner forming roll disposed inside the can body. It can be suitably applied to the production of containers.

DESCRIPTION OF SYMBOLS 10 trunk | drum 13 big bead part 40 inner side forming roll 41 annular recessed part 50 outer side forming roll 51 annular convex part 100 metal container (metal can)

Claims (8)

  An inner forming roll and an outer forming roll are rotatably arranged inside and outside the body portion of the metal container, and the outer forming roll is pushed into the inner forming roll to bead the body portion of the metal container. In the method of manufacturing a metal container for forming a neck portion and / or a neck portion, the inner forming roll has an annular recess formed on a side surface, which includes a bottom surface portion and both side walls corresponding to the bead portion or the neck portion of the body portion. The corner R portion of the side wall corresponding to at least the maximum diameter is an R portion formed of a curve that smoothly increases from the annular recess starting point corresponding to the maximum diameter toward the boundary point with the side wall. By doing so, the convex deformation in the vicinity of the processing portion of the body portion contacting the vicinity of the annular recess start point of the inner forming roll is reduced. The method of production.   The method for manufacturing a metal container according to claim 1, wherein a part or all of the curve is configured based on a clothoid curve.   The method for producing a metal container according to claim 1 or 2, wherein the bead portion of the metal container is a big bead having a depth of 2 mm or more.   The convex deformation in the vicinity of the processing portion of the body portion that contacts the vicinity of the annular recessed portion starting point corresponding to the maximum diameter of the annular recessed portion of the inner forming roll is suppressed to 0.15 mm or less from the protruding amount from the can body flat portion. The method for producing a metal container according to any one of claims 1 to 3. An inner forming roll for forming a bead portion and / or a neck portion in a body portion of a metal container in cooperation with the outer forming roll;
In an inner forming roll having one or more annular recesses recessed inward in the radial direction on the side, at least the corner R portion of the side wall corresponding to the maximum diameter of the annular recess, the annular recess start point corresponding to the maximum diameter An inner forming roll characterized in that it is an R portion formed of a curved line which is not constant but smoothly increases and continues toward the boundary point with the side wall.   The inner forming roll according to claim 5, wherein a part or all of the curve is configured based on a similar clothoid curve obtained by similar enlargement conversion of a part of the clothoid curve.   The inner forming roll according to claim 6, wherein the starting point of the annular recess is an origin of a clothoid curve.   The starting point of the annular recess of the metal container is the origin of the clothoid curve, and the boundary point is the first quadrant or the third quadrant in which the sign of the amount of change of X with respect to the parameter T in the clothoid curve changes from positive to negative. The inner forming roll according to claim 1, which is a point corresponding to each inflection point.

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