JPS6247093B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a small pressure-resistant container used as a beer barrel or the like. This type of container is made of thin plates such as aluminum, and is divided into, for example, a lower piece (first piece) that forms the body and an upper piece (second piece) that forms the lid.
Both pieces are joined together as shown in FIG. 1, which is a partial vertical cross-sectional view. That is, in FIG. 1, on the inner surface 13 (left surface) of the cylindrical opening 1 at the upper end of the lower piece,
Fit the annular recess 3 that has entered the lower part (inside the container) of the upper piece 2, and connect the outward flanges 5, 6 (double-dashed lines) of the opening 1 and the recess 3 to 5', 6' (solid lines). It is wrapped like this. In that case, the plate thickness t is
If it is less than 0.4 mm, it cannot be processed, so it is necessary to make it thicker than that, but the thicker the plate thickness t, the higher the material cost, so in reality, the plate thickness t should be
It was desired that the diameter be 0.4 to 0.6 mm. However, if the plate thickness t is made thinner, the strength of the recess 3 decreases accordingly, so when the container is filled with beer, the temperature of the beer in summer reaches 40℃ and the internal pressure becomes 4.2Kg/cm2 ^.
When the pressure is as high as G, the inner and outer walls 7, 8 and the bottom wall 9 forming the recess 3 roll upward as shown by 3a, and eventually they stand upright as shown by 3b, causing the seaming part 10 to come off. There is a risk that an accident may occur due to loosening. Therefore, it has been desired to calculate in advance the shape of the recess 3 having high strength so that the plate thickness t can be reduced and the recess 3 can be given sufficient strength to prevent curling. . However, the shape of the recess 3 is complex, and the fulcrum P of the uphill movement continuously moves from the lower part of the outer wall 8 to the upper part P1, so it is actually impossible to accurately calculate its strength theoretically. Therefore, it is difficult to finish the recess 3 in a shape with high strength, and the above-mentioned accident cannot be completely prevented without increasing the plate thickness t. This resulted in the problem of increased material costs. The present invention systematizes the relationship between the shape of the recess and its strength through experiments, thereby forming the recess in a shape with sufficient strength, and making it possible to easily fit such a recess into the opening of the lower piece and securely. The cylindrical outer wall of the recess before fitting is made into a tapered shape that becomes slightly smaller in diameter as it goes toward the bottom wall of the recess, and the cylindrical outer wall in the tapered state The part near the bottom wall of the recess is separated from the inner surface of the opening by a distance approximately equal to the plate thickness, and the recess The entire outer surface of the inner wall of the recess is made into a smoothly curved convex surface, the bending radius of the bottom wall of the recess is made approximately equal to the plate thickness, the angle between the outer wall and the inner wall of the recess is made as small as possible within the range where the chuck can be inserted, and seaming is performed. Sometimes, an annular chuck was inserted into the recess so that the outer wall of the recess was in close contact with the opening, and in this state, a seaming roll was pressed against the opening from the outside in the radial direction to tighten the seam, and the chuck and the seaming roll were removed. In this state, a spring back is generated on the cylindrical outer wall of the recess, and the force due to the spring back is applied to the seaming portion to increase the seaming strength. This is explained by: In FIG. 2, the same reference numerals as those in FIG. 1 indicate corresponding parts, and the double-dotted chain line portion indicated by the symbol 3' indicates the recess before fitting the chuck 11 (FIG. 3), which will be described later. , First, the recess 3 after seaming is completed, which is indicated by a solid line, will be explained. The applicant has experimentally found that the smaller the bending radius r of the recess bottom wall 9, the higher the strength of the recess 3 (strength against curling up), and that it is almost impossible to make the bending radius r smaller than the plate thickness t. Therefore, the radius r is made to approximately match the plate thickness t (0.5 mm). M is the angle between the inner wall 7 and the outer wall 8, in particular the angle between the line P and the line Q (on the vertical plane containing the center line of the container) in FIG. P is a straight line on the inner surface 18 (left surface) of the outer wall 8, and line Q is a circle S inscribed in the upper surface 19 of the bottom wall 9.
from the left, and the outer surface 17 (right surface) of the inner wall 7
It is a straight line that touches the arc of radius R + t formed by from the right at the point where the arc touches the circle S. In other words, the line Q is a straight line n that connects the center O of the circle S and the arc center m of the outer surface 17. It is a straight line at right angles to. The applicant confirmed through experiments that the smaller the angle M, the higher the strength of the recess 3.
Confirm the following concrete relationship between angle M, plate thickness t, and strength (pressure resistance Kg/cm ² G) for a container with (inner diameter of opening 1) 15.5 cm and bending radius r = plate thickness t. did.

[Table] As is clear from the table above, when the plate thickness t = 0.5 mm, in order to withstand an internal pressure of 4.2 kg/cm ² G, the angle M must be 10° or less;
If the angle M is smaller than 0°, it becomes difficult to insert the chuck 11 into the recess 3 and tighten the seam as shown in FIG. It is set at 10°. Also, conventionally, the radius R (shoulder radius) of the outer surface 17 is the same as the trunk diameter L.
It is said that the pressure resistance of the container is maximized when the radius R is set at 1/4 to 1/10.
It is determined to be 1/4L to 1/10L, and in the illustrated embodiment, the radius R is determined to be (0.17 to 0.18)L. Note that the force applied per unit length (circumferential direction) of the concave portion 3 and the seaming portion 10 due to internal pressure is proportional to the body diameter L, so if the body diameter L increases, the force must be adjusted accordingly. It is necessary to reduce the angle M. When the angle M and radius r of the recess 3 are made smaller as described above, the distance l between the lowest part e of the bottom wall 9 and the inner surface 13 of the opening becomes extremely small (approximately 1 mm). As a countermeasure for this, in the present invention, the outer wall 8' of the recess 3' before the chuck 11 is inserted (before it is inserted into the opening 1) is replaced with the bottom wall 9, as shown by the two-dot chain line. It is formed in a tapered shape that becomes slightly smaller in diameter as it goes toward the outer wall 8' side, and there is a distance l2 of about 0.5 mm between the lower end 8a' of the outer wall 8' and the inner surface 13 of the opening (a short distance l2 that is approximately the same as the plate thickness t). distance). By forming the recess 3' in the above-described shape, the distance l1 between the lowest part e' of the bottom wall 9' and the inner surface 13 of the opening increases to approximately 1.5 mm, so that the recess 3' can be easily inserted into the opening 1. can do. By setting the distance l2 small, the upper piece 2 can be accurately (concentrically) fitted into the opening 1 in a state close to that of the opening 1 before the seaming process. The dimensions can be set accurately over the entire circumference, and the strength of the seamed portion 10 can be increased. After inserting the recess 3' into the opening 1 as shown,
As shown in FIG. 3, the annular chuck 11 is fitted into the recess 3' from above to bring the outer wall 8 of the recess 3 into close contact with the opening 1, and the flanges 5, 6 and the opening 1 are fitted radially outward (rightward). Then, the seaming roll 12 is brought into pressure contact to perform seaming. When the chuck 11 is removed after the seaming is completed, the lower half of the outer wall 8 separates from the opening 1 due to the springback as shown in FIG. A force is applied to the seaming portion 10 to improve the seaming strength of the seaming portion 10. Note that at least in the section from the bottom wall 9 to a position at the same height as the upper end of the seaming part 10 (a position radially inside the opening end of the seaming part 10), the inner wall outer surface 17
The entire surface is a smoothly curved convex surface, and the outer surface 1
The chuck 11 fitted along 7 has a thickness that increases smoothly as it moves upwards. Therefore, the chuck 11 has high strength and the tapered outer wall 8'
When the chuck 11 is deformed outwardly, problems such as damage to the chuck 11 do not occur. As explained above, according to the present invention, the angle M between the inner wall 7 and the outer wall 8 of the recess 3 is made smaller, and the bending radius r of the bottom wall 9 is made smaller, so that the strength against turning over of the recess 3 is increased, and the container Moreover, since the outer wall 8' before fitting into the opening 1 is tapered so that the diameter becomes smaller as it progresses toward the bottom wall 9', the angle M and the bending radius r can be made smaller. The recess 3' can also be easily fitted into the opening 1.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional partial view showing a connecting portion of a conventional container, and FIGS. 2 and 3 are vertical cross-sectional partial views showing a connecting portion of a container according to the present invention. 1... Opening, 3... Recess, 5, 6... Flange, 7... Inner wall, 8... Outer wall, 9... Bottom wall, 10
... Sealing portion, 11... Chack, 12... Sealing roll, 13... Opening inner surface, 17... Inner wall outer surface,
r...Bending radius.

Claims (1)

[Claims] 1. Fit the annular recess that has entered the inside of the container of the second piece on the end wall side of the pressure container into the inner surface of the cylindrical opening of the first piece on the body side of the pressure container, so that both the opening and the recess face outward. In a method for manufacturing a pressure-resistant container in which a flange is tightened, the cylindrical outer wall of the recess before fitting is tapered so that the diameter becomes slightly smaller toward the bottom wall of the recess, and the bottom wall of the recess of the cylindrical outer wall in the tapered state is Separate the nearby part from the inner surface of the opening by a short distance approximately equal to the thickness of the plate,
The entire outer surface of the inner wall of the recess in the section from the end on the bottom wall side of the recess to the radially inner position of the open end of the opening is a smoothly curved convex surface, and the bending radius of the bottom wall of the recess is equal to the plate thickness. The angle between the outer wall and the inner wall of the recess is made as small as possible within the range in which the chuck can be inserted, and when tightening, the annular chuck is inserted into the recess so that the outer wall of the recess is in close contact with the opening, and in this state the opening is closed. A seaming roll is pressed from the outside in the radial direction to tighten the seam, and when the chuck and the seaming roll are removed, a spring back is generated on the cylindrical outer wall of the recess, and the force of the spring back is used to tighten the seam. 1. A method for manufacturing a pressure-resistant container, characterized in that the seaming strength is increased by increasing the seaming strength.