JPH049232A - Method for necking metallic can body part - Google Patents

Abstract

PURPOSE:To reduce working load and to prevent a wrinkle from generation by specifying the sectional form of a tapered part of a necking die and composing the innermost part of the tapered part of a series of curves having rectilinear parts. CONSTITUTION:In the necking work of drawing the opening end part of a metallic can body, the sectional form of the tapered part of the necking die is composed of an inlet angle theta1 of the tapered part of the necking die which is <=20 degrees and the outlet angle theta2 which is theta1<theta2<35 degrees. Further, rectilinear part Lb is provided on the innermost side of the necking tapered part. Thereby, an excessive drawing in the latter half of the necking work can be prevented, a relief is removed between the die tapered part 1b and the opening end part 5c and the generation of wrinkles is prevented by effective actuation of blank holding force. Further, since the advance of the metal sheet to the gap 6 of the opening end part is guided smoothly, unbending load is lowered, axial load is diminished and the metallic can body part is prevented from buckling.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for manufacturing a neck-in can body. More specifically, the present invention relates to a method for manufacturing metal can bodies that reduces neck-in machining loads and prevents wrinkles.

[Prior art] Filling and sealing cans for beer, juice, carbonated drinks, etc. currently in general use are soldered cans, welded cans, glued cans, and seamless cans (squeezed and squeezed cans) depending on the manufacturing method. It is divided into ``Dokican'' and other types. Conventionally, the opening end of the can body of such cans is necked in, then flanged, and the can lid is double-sealed, and the outer diameter of the double-sealed part is made smaller than the outer diameter of the can body. It is more commonly practiced. This neck-in process improves pressure resistance, reduces the diameter of the can lid to save material, and prevents dents in the can body due to contact between the double seam and the can body during transportation. It has economic and technical advantages. Conventionally, as shown in FIG. 313, neck-in processing of a metal can body is performed by inserting an open end 5c of the metal can body into a gap between a necking die 1a having a tapered part formed from a truncated conical inner surface and a center core 3. This is done by press-fitting and squeezing into a predetermined shape. To explain this conventional method in more detail, first, the metal can body is defined, and by simultaneously pushing down the necking die 1a and the center core 3, the metal can body opening end 5c moves inward along the necking die tapered portion 1b. Narrowed down. Next, the center core 3 is stopped, only the necking die 1a is pushed down and the necking is advanced downward, and the lock end tip jiit 5c enters the gap 6 between the necking die 1a and the center core 3 to form a reduced diameter portion. Another method is to arrange the necking die 1a and the center core 3 so that a gap 6 for bending back is formed in advance, and to perform the necking process by simultaneously pressing down the necking die 1a and the center core 3 until the end of the process. There is also a way to do this. [The problem that the invention attempts to solve! ! ] In recent years, can body materials have become thinner and stronger, and this has led to problems such as buckling of the can body and wrinkles in the neck during necking. In order to solve this problem, A, Special Publication No. Sho 57-160527, Publication IIB, Japanese Unexamined Patent Publication No. Sho 5.
Methods such as those disclosed in Publication No. 6-105838 C0 and Japanese Patent Application Laid-Open No. 55-45594 have been used. However, although method A has the effect of preventing wrinkles from forming, since the exit angle (maximum angle) is as large as 35'' to 50'' and consists only of concave curved surfaces, There is a problem in that the bending unbending load at the exit portion of the necking die that transitions becomes large, and this excessive bending unbending load increases the neck-in load, causing buckling in the thinned can body. In addition, method B above attempts to prevent wrinkles and buckling by applying ultrasonic waves during processing, and although it is certainly effective, it requires incorporating an ultrasonic vibrator into the mold. This makes the device complicated, and requires a separate ultrasonic generator, which leads to an economic cost increase. Further, in method C, the drawing process is performed twice, which can prevent the occurrence of wrinkles and buckling, but increases the number of steps and reduces the dynamic band. The present invention solves the problems of the prior art and easily prevents buckling of the can body during necking, buckling at the initial stage of necking, and wrinkling of the neck by reducing the neck-in load. This provides a method to do so. [Means for Solving the Problems 1] The present invention provides neck-in processing in which the opening end of a metal can body is drawn. angle θ2 to θ1
This neck-in processing method for a metal can body is characterized in that θ2<35' and the neck-in processing method for a metal can body is formed by a series of curved lines having a straight portion at the innermost part of the tapered part. In addition, this is to smooth the relative movement between the necking die and the metal can body during neck-in processing. The plurality of curves and straight lines forming the cross-sectional shape of the necking die taper part must be smoothly connected. [Operation] The following description will be made with reference to figures of embodiments of the present invention. FIG. 1 is a sectional view of a necking die for explaining the present invention in detail, FIG. 112 is a schematic diagram showing a tapered part of the necking die for explaining the present invention in detail, and FIG. FIG. 3 is a cross-sectional view showing the state of wrinkles that occur during processing using a die. Furthermore, in each of the above figures, the necking die 1a and the center core 3 are pushed down from the top to the bottom of the drawing relative to the metal can body, and the metal can body is first drawn to reduce its outer diameter, and then It is bent in the opposite direction and machined in the upward direction. First, the entrance angle θl of the necking die taper part, which is schematically shown in FIG.
It is preferable to set it to 8@. When the entrance angle θ1 exceeds 20@, the opening end of the metal can body undergoes rapid bending deformation at the necking die entrance, and the neck-in load rapidly increases, and at the point when the processing progresses as shown in Figure 14. At this point, the opening end of the metal can body separates from the necking die taper, and as a result, the pressing force from the necking die taper no longer acts on the opening end of the metal can body, and wrinkles 5d occur in this area. On the other hand, if the entrance angle θ1 is too small, a sufficient amount of necking cannot be obtained. Therefore, the entrance angle θ1 is 20'
It is preferably the following, and particularly preferably 10" to 18 degrees. Next, the exit angle θ2 of the necking die taper part, which is schematically shown in Figure J12, is set to θ1<θ2<35', and in particular, the angle difference θ2-01 is preferably 10' or more and 20' or less. If the exit angle θ2 is 35'' or more, the occurrence of wrinkles at the open end 5c of the metal can body can be suppressed, but the axial load due to necking increases. Furthermore, in the unbending process in which the metal can body opening @ portion 5c is bent in the opposite direction and enters the gap 6 between the necking die 1b and the center core 3 after the drawing process, the unbending load increases, and the axial load further increases. This axial load is applied to the can body, causing buckling. In addition, the reason why the inlet angle θ1 is set to the outlet angle θ2 is that if the relationship is reversed, the cross-sectional shape becomes convex and a sufficient amount of necking cannot be obtained. The pressing force from 1b no longer acts, and wrinkles occur in this area. In addition, if the difference between the entrance angle θ1 and the exit angle θ2 is small, the cross-sectional shape of the die taper section becomes almost linear, and a sufficient amount of necking cannot be obtained. The open end of the metal can body undergoes rapid deformation during the necking process, resulting in wrinkles and buckling. Next, if the necking die taper part is formed in a curved line to the innermost side, the opening end of the metal can body will enter the gap from a direction close to perpendicular to the gap, resulting in excessive bending when bending back after drawing. Load is required. Further, due to the springback of the metal can body, the necking die taper portion lifts up, and the pressing force from the die taper portion no longer acts, causing wrinkles to occur in this portion. In the present invention, I! By providing iii & 1 part Lb on the innermost side of the necking die taper part shown schematically in Figure 2, excessive narrowing in the latter half of the necking process is prevented, and the open end 5 of the die taper part 1b is
The generation of wrinkles is prevented by eliminating the lifting of c and applying the pressing force effectively, and furthermore, by smoothly guiding the opening end into the gap 6, the bending unbending load is reduced and the axial load is reduced. This can prevent buckling of the metal can body. Although the length of the straight portion Lb is limited by the amount of necking, it can be adjusted by selecting the inlet angle θ1 and the outlet angle θ2, and can be adjusted based on experiments, calculations, etc. on the material of the metal can body, the amount of necking, and the lubrication conditions. It is also possible to find the optimal relationship between the length, entrance angle, and exit angle according to the combination of the following. The structure of the new surface curve on the entrance side of the B straight part Lb does not need to be convex, and may be formed using straight lines as shown in the schematic diagram of this embodiment, or may be formed by combining a large number of circular arcs and straight lines. You can. [Embodiment 1] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In Figure 2, θ1=15''', θ2=300r
+=5mmR, r2=7. 5mmR, r3=2mmR
Using a necking die, make the can body wall thick. , 110m
When necking was performed at a drawing rate of 4.5% on a drawn and ironed can with an opening end wall thickness of 0.165 mm, no wrinkles or buckling occurred. On the other hand, θ 1=02=30', r+=2mm
R, r3 = 2 mm When necking was performed in the same way using a conventional necking die with a new surface consisting of a straight section of R and curved sections at both ends, buckling did not occur, but as shown in Figure 4. Many wrinkles appeared on the open end of the metal can body. Further, when the necking load was measured, it was 180 Kgf in the conventional necking die, but it was reduced to 160 Kgf in the necking die of the present invention. Next, when necking was performed using a conventional necking die and changing the gap from 0.25 mm to 0.20 mm to prevent wrinkles, a shoulder was formed in the can body. Effects of the Invention As described in detail above, according to the present invention, wrinkles can be prevented from occurring during necking when the can body is made thinner, and the necking load can be reduced to improve seat Ji1.
This has the effect of preventing the occurrence of defects such as

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a necking die for explaining the present invention in detail, FIG. 2 is a schematic diagram showing the tapered part of the necking die for explaining the present invention in detail, and FIG. 13 is a diagram showing a conventional method. FIG. 14 is a new view showing the state of occurrence of wrinkles during processing using a conventional necking die. 1a...necking die, 1b...necking die taper part 2...
...Guide ring, 3...Engraving of center core drawing (no change in content) Negative 1 mountain vJλ mouth 4...Holding body, 5a...Can body, 5
b...Neck part, 5c...Open end, 5d...Wrinkle, 6...Gap,
θ】・・・Entrance angle, θ2・・・Exit angle,
La, Lb...Straight section, r7, r2, r3...Curved section Applicant Sky Aluminum Co., Ltd. LF oral procedure amendment (method) % formula % Name of invention Metal Relationship to the case of a person who corrects the neck-in processing method of can bodies by 3 degrees

Claims (1)

[Claims] 1. In the neck-in process of drawing the opening end of a metal can body, the cross-sectional shape of the tapered part of the neck-in die has an entrance angle θ.
_1 is 20° or less, exit angle θ_2 is θ_1<θ_2<3
A neck-in processing method for a metal can body, characterized in that the neck-in processing method for a metal can body is formed by a series of curved lines having an angle of 5° and a straight line portion at the odoriest part of the tapered part.