JPH03248729A - Manufacture of multi-stage necked-in can and tool therefor - Google Patents

Abstract

PURPOSE:To manufacture a multi-stage necked-in can difficult to generate vertical wrinkles on an opening part having a contracted diameter by bending the neighborhood of an end face of an opening end part a little to the inside in the radial direction in each die necking before a final die necking. CONSTITUTION:The neighboring part 7 of the end face of an opening end part 10 formed by each die necking before the final necking is bent a little to the inside in the radial direction. Consequently, when this opening end part 10 is inserted into a clearance part between a necking die 2 and a core 4 for the next necking, the neighboring part 7 of the end face grows easily intimate with a shoulder forming curvature part, etc., and is deformed fully along the shoulder forming curvature. Since the innermost end of the clearance between the necking die 2 and the core 4 is inclined a little to the inside in the radial direction, each necking tool used before the final necking can incline the neighboring part 7 of the end face to the inside in the radial direction when necking is performed. In this way, a multistage necked-in can difficult to generate vertical wrinkles on the opening part contracted in diameter can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of application of M collection) The present invention is used for beer cans, carbonated beverage cans, coffee beverage cans, and the like. The present invention relates to a method and tool for manufacturing a multi-stage neck-in can body having a multi-stage neck-in portion at an open end.

(Prior art) The open end of the nine can bodies is pushed into the gap between the necking die and the core of the necking tool to perform necking processing (in this introduction, type C necking processing is referred to as die necking processing). A method for manufacturing a can body having a neck-in-type can is widely put into practical use.

In particular, the multi-stage neck-in can body, which is formed by performing the above-mentioned pressing on each necking tool whose diameter in the nine gaps is successively smaller, has advantages such as reduced material costs due to the miniaturization of the lid and improved design. Because of this, the fields of its use have been increasing recently.

However, in order to further reduce material costs, 5 the body of the can, and therefore the open end, are made relatively thin and hard. .10- In the case of deep-drawn cans etc. made of tin-free steel (and both sides covered with polyethylene terephthalate film), when a multi-stage neck-in part is formed using the conventional die necking method, a large number of neck-in parts are formed in the four parts due to diameter reduction. Vertical wrinkles are likely to occur, and these vertical wrinkles cause cracks during flange processing or double seaming, resulting in a problem of impairing the airtightness of the double seaming portion. Furthermore, the axial load increases during the above-mentioned processing, resulting in the problem that buckling of the body is apt to occur.

(Problems to be Solved by the Invention) The present invention provides a multi-stage neck-in can that is difficult to form vertical wrinkles in the four diameter-reduced portions even if the open end of the can is relatively thin (and hard). The purpose is to provide manufacturing methods and tools for.

(Means for Solving the Problems) The method for manufacturing a multi-stage neck-in can body of the present invention is a method for manufacturing a multi-stage neck-in can having a multi-stage neck-in portion at an open end, and comprises The die necking process is characterized by slightly bending the opening end near the end surface slightly inward in the radial direction.

A manufacturing tool for a multi-stage neck-in can body according to the present invention is a manufacturing tool for a multi-stage neck-in can having a multi-stage neck-in portion at an open end, and the tool is equipped with a necking die and a core, and the tool is equipped with a necking die and a core. Each of the tools used in this invention is characterized in that a portion at the far end of the gap between the necking die and the core is slightly inclined radially inward.

(Function) In the conventional die necking tool, the gap between the necking die and the core has a right cylindrical shape from the inlet end to the back end. In this case, the portion near the end surface of the neck-in portion formed is inclined radially outward (Fig. 4; Japanese Patent Publication No. 53-390
(See Figures 2 and 4 of Publication No. 19; Figure 4 (g) of Special Publication No. 6366616).

When further necking is performed on the open end of a neck-in can body that has a portion near the end surface that is inclined outward in the radial direction, the portion near the end surface that is inclined outward may be the shoulder forming curvature portion of the necking die or the drawing curvature portion ( Vertical wrinkles are likely to occur because they are not pushed into the gap sufficiently along the lines shown in Figure 1 (a > 2a, 2b), and compressive stress is applied in the circumferential direction during squeezing. it is conceivable that.

In the case of the present invention, the portion near the end face of the open end formed in each die necking process before the final die necking process is slightly bent radially inward. Therefore, when this open end is pushed into the gap between the necking die for the next necking process and the core, the area near the end surface easily conforms to the shoulder forming curvature, etc., and is therefore deformed sufficiently along the shoulder forming curvature. Ru. Therefore, the opening end is relatively thin.

Even if the material is hard, it is thought that vertical wrinkles are less likely to occur in the four diameter-reduced portions including the portion near the end face.

Each necking tool used before the final necking process of the present invention has a portion at the far end of the gap between the necking die and the core that is slightly inclined inward in the radial direction, so that the end face The proximal portion can be bent slightly radially inward.

(Example) An example of manufacturing a three-stage neck-in can body will be described.

In FIG. 1(a), l is a necking tool for forming the first stage (lowest stage) neck-in part.

Necking die 2. Guide ring 3. Core 4. and a core holder 5. The necking die 2 includes, from the inlet side, a shoulder forming curvature part 2a, a drawing curvature part 2b, and a right cylindrical part 2c.
, a bending curvature portion 2d for slightly bending a portion near the end face of the open end portion inward in the radial direction, and an inclined portion 2e extending diagonally inward and upward. The inclination angle θ of the inclined part 2e is 3 to 1
The slope width d at the upper end of the slope portion 2e (at the level of the stepped portion 7) is preferably approximately 0.10 to 0.401 na+.

The core 4 has a cylindrical shape except for the deep part, and the parts facing the bent curvature part 2d and the inclined part 2e in the deep part have a diameter of 9.
It has a curvature portion 4b and an inclined portion 4C. Inclined part 4c
The inclination angle δ is preferably equal to or slightly larger than the inclination angle θ.

The width of the gap 6 between the cylindrical portion 4a of the core and the right cylindrical portion 20 of the necking die is set to be slightly thicker than the wall thickness of the open end lO of the three can bodies 9. At the inner end of the core 4, the holder 5 forms a stepped portion 7 that extends outward in the radial direction.

9 is a can body such as a draw-formed can, an iron-drawn can, a welded can, etc.; 10 is a generally cylindrical open end whose outer diameter is slightly smaller than the inner diameter of the guide ring 3; .

Now, with the can body 9 fixed, if the tool l is pushed in the direction of the arrow, the open end lO will become l as shown in Fig. 1(b).
A shoulder portion 11 is formed by the R shadow forming curvature 2a.

Moreover, it is pushed into the gap part 6 while being squeezed by the aperture curvature part 2b. At the beginning of the push-in, the end face 10a is the cylindrical part 4 whose core is
a, but the width of the gap 6 is slightly larger than the thickness of the opening end 10, so it is immediately reversed, and as shown in Figure 9, the end face vicinity part 12 faces slightly outward and upward, and the left end of the end face 10a. is pushed in while contacting the right cylindrical portion 2C.

If the pushing is continued further, as shown in FIG. 1(c), the end surface vicinity portion 12 is bent inward by the bending curvature m2d, enters along the inclined portion 2e, and the end surface 10a is bent into the stepped portion 7.
The formation of the first stage neck-in portion 13 is completed at the time when the two are almost in contact with each other.

Figure 2 shows the one-stage neck-in can body 9 extracted from tool l.
′ is shown. The bent portion below the end surface vicinity portion 12 shown in FIG. 1(c) is corrected by springback, and the shoulder portion 11. A neck-in portion 13 is formed of a right cylindrical reduced-diameter portion 14 and a portion 12 near the end surface that is slightly inclined diagonally inward and upward.

The width of the slope at the end surface 10a is slightly smaller than the slope d of the slope 2e due to springback, but the width is usually about 0.01 to 0.25 mm.

Reference numeral 21 in FIG. 3(a) indicates a tool for forming the second stage (middle stage) neck-in part, which includes the inner diameter of the right cylindrical part 22c of the necking die 22 and the cylindrical part 24a of the core 24. The structure is the same as that of the tool 1 except that the diameters of the diameters of the right cylindrical portion 2C of the necking die 2 and the diameter of the cylindrical portion 4a of the core 4 are smaller. In other words, the necking die 22 has the inclined portion 22e and the core 24.
is provided with an inclined portion 24c.

In this case, the end surface vicinity portion 12 of the can body 9 to be pushed in is slightly inclined diagonally inward and upward, so when the tool 21 is pushed in the direction of the arrow, the shoulder forming curvature portion 22a and the drawing curvature portion 2
2b into the gap 26, and no continuation occurs in the end surface vicinity portion 12 and the reduced diameter portion 14 below it during the insertion, and as shown in FIGS. 3(b) and 3(c). As shown in FIG. 1, as in the case of FIG.
A can body 9'' with 8 is formed.

Reference numeral 31 in FIG. 4 indicates a tool for forming the third stage (top stage) neck-in part. The diameters are smaller than the inner diameter of the right cylindrical portion 22c of the necking die 22 and the diameter of the cylindrical portion 24a of the core 24, and the right cylindrical portion 32c and the cylindrical portion 3.
The point where 4a extends to the rear end and there is no slope is the tool 21.
different from. That is, tool 31 is a conventional necking tool.

Also in this case, since the end surface vicinity portion 27 of the can body 9'' to be pushed in is slightly inclined diagonally inward and upward, a three-stage neck-in can body 9 (final can body) without a continuation plate is formed.

However, the end face vicinity portion 37 after molding is slightly inclined outward and upward. Such an outwardly inclined end surface vicinity portion 37
is advantageous for forming flange parts, and there is no continuation version, so
Cracks are less likely to occur during flange formation or double seaming.

The present invention is not limited to the above embodiments.
For example, the neck-in portion of the neck-in can body to be formed is 2
The necking die and the inclined portions of the core may be curved portions bent inward in the radial direction.

(Effects of the Invention) The present invention has the advantage that even if the opening end of one can body is relatively thin and hard, it is possible to manufacture a multi-stage neck-in can body in which a continuation plate is difficult to occur at the reduced diameter opening. play.

[Brief explanation of drawings]

FIGS. 1(a), (b), and (c) are longitudinal sectional views of main parts showing the process of forming the first stage neck-in part in the present invention,
FIG. 2 is a vertical sectional view of a main part of a one-stage neck-in can body formed by the tool of FIG. 1, and FIG. 3(a). (b) and (c) are longitudinal sectional views of main parts showing the process of forming the one-stage neck-in can body shown in Figure 2 into a two-stage neck-in can body, and Figure 4 is a longitudinal sectional view of the main part showing the process of forming the one-stage neck-in can body shown in Figure 2 into a two-stage neck-in can body. FIG. 3 is a longitudinal sectional view of a main part showing a state in which a three-stage neck-in can body is formed from the formed two-stage neck-in can body. 1.21... Necking tool, 2.22... Necking die, 2e, 22e... Inclined part, 4.24... Core, 4c, 24c... Inclined part, 6.26... Gap part, 9
・3-stage (multi-stage) neck-in can body, 10...opening end,
12.27 - Near the end surface. flute diagram

Claims (2)

[Claims] (1) In the manufacturing method of a multi-stage neck-in can body having a multi-stage neck-in portion at the open end, during each die necking process before the final die necking process, the area near the end face of the open end is moved slightly inward in the radial direction. A method for manufacturing a multi-stage neck-in can body characterized by bending the can body. (2) A manufacturing tool for a multi-stage neck-in can body having a multi-stage neck-in portion at the open end, the tool is equipped with a necking die and a core, and each tool used before the final necking process has a necking die and a core. A manufacturing tool for a multi-stage neck-in can body, characterized in that a portion at a rear end of each gap between the two is slightly inclined radially inward.