KR20020042953A - Structure of a Ironing punch for improving the strippability of a steel Drawn and Ironed can - Google Patents

Abstract

PURPOSE: An ironing punch is provided to prevent roll-back generated in the process of separating the can from the punch after completing body forming of the can during manufacturing of a steel drawn and ironed can and improve stripping defects of the can. CONSTITUTION: The ironing punch for improving strippability of the steel drawn and ironed can comprises a concave grooved part(42) which is formed on the outer circumferential surface of an ordinary ironing punch to improve stripping performance of the steel drawn and ironed can, a depth of which is 2 to 8% of a wall thickness of a completed can, a length of which is 8 to 16% of a height of the can, and a width of which is 8 to 20% of a radius of the can, wherein the concave grooved part(42) is arranged in such a manner that curvature of both end parts is 50% of the width of the concave grooved part(42), and an interface between the concave grooved part(42) and the surface of the punch is formed in a smooth curvature shape so that a distance between each grooved parts in a circumference direction of the punch is 2 to 5 times of a width of the grooved part, and wherein two rows of the grooved part are arranged in a length direction, namely, axis direction of the punch.

Description

Structure of a Ironing punch for improving the strippability of a steel Drawn and Ironed can}

The present invention relates to a structure of an ironing punch for reducing the rollback occurring in the process of separating the can from the punch after the completion of the body shaping of steel D & I can made of stone steel sheet, and has a large concave shape on the punch surface. It is related with the ironing punch which can form the groove part and can improve the extractability of a can.

Generally, a can is an iron container manufactured to contain a liquid liquid and processed food using a metal material, and is divided into a three-piece can and a two-piece can according to the number of components. The three-piece can consists of three parts: the lid, the body and the bottom, while the two-piece can is molded integrally with the body and the bottom. Therefore, two-piece cans are widely used as storage containers for beverages and foods because they have higher storage safety, higher production efficiency, and lower manufacturing cost than three-piece cans.

Two-piece cans are divided into DRD cans (Drawn & Redrawn cans), D & I cans (Drawn & Ironed cans), and Drawn cans, depending on the processing mode applied to manufacturing. DRD cans are produced by drawing and several redrawing processes, so the wall thickness of the final can is almost the same as the thickness of the original material, whereas the D & I can is an ironing process that makes the wall thickness thin after drawing and redrawing. The wall thickness of the can is 60% thinner than the material thickness. Therefore, when the same cans are manufactured, D & I cans are used for storage containers such as beer or carbonated drinks because they use less material and are lighter than DRD cans. Here, D & I cans are mainly used as tin plate or aluminum alloy, but steel sheets are often used because steel materials are inexpensive and stable supply is possible.

Fig. 1A shows the manufacturing process of a conventional two-piece D & I can and the shape of the product obtained for each process.

(A), (b), and (c) of FIG. 1A show a drawing process, a redrawing process, and an ironing process, respectively. As shown in the drawing, the diameter of the desired can 20 is obtained by deep drawing and redrawing processing with a roughened steel sheet having a thickness of about 0.22 to 0.28 mm, and also by ironing. The wall thickness of 20) is reduced while increasing the height to obtain the final finished can 20.

In particular, a more detailed description of the ironing process of manufacturing the finished can is shown in FIGS. 1B to 1E, and the configuration thereof includes the punch 100 and the first and second dies 26 and 27. , 28). The inner diameters of the dies 26, 27, 28 are designed to gradually decrease in correspondence with the advance direction of the punch 10. Therefore, in the forward stroke of the punch 10, as shown in FIG. 1B, the raw material that has been redrawn, that is, the can 20, may be continuously passed through the dies 26, 27, 28 of three stages while being stuck in the punch 10. FIG. The wall of the can 20 gradually becomes thinner and at the same time the height of the can 20 increases as it passes through the space between the respective dies 26, 27, 28 and the punch 10.

As described above, the ironing process in the D & I can manufacturing process forms the body of the can 20 through three ironing steps, and the wall thickness of the final finished can 20 becomes very thin, approximately 0.08-0.10 mm. The can 20, which has completed the body shaping by three ironing processes, is then moved forward while being stuck in the punch 10, and is moved to the top dead center of the punch stroke, forming a bottom shape of the can 20. It goes through a molding process.

The punch 10 then starts a return stroke, at which time the extraction process of the can 20 separating the can 20 caught in the punch 10 from the punch 10 is performed at the same time.

FIG. 1C is a diagram schematically illustrating the reverse stroke of the punch 10 and the extraction process of the can. Extraction of the can 20 is made by the extractor 30 provided behind the third die 28, and Fig. 1D is an enlarged excerpt of the main portion thereof.

Figure 1e shows the shape seen from the front of the extractor 30, the extractor 30 is usually composed of 16 to 20 pieces 32 and the outer surface is supported by a spring (not shown) is shown in Figure 1a and Likewise, when the punch 10 moves forward, the piece pieces 32 of the extractor 30 are spread out to the outer surface so that the can 20 can easily move forward. And the can 20 is separated from the punch 10.

Since the ironing process of this process is a process of thinning the thickness of the can 20 material, the material in the process is subjected to severe plastic deformation. Therefore, after the processing is completed, residual stresses remain in the circumferential direction, the axial direction, and the thickness direction of the wall portion of the can 20, respectively, which acts as one of the main factors for determining the difficulty of the can 20 extraction process. Since the circumferential residual stress of the wall portion of the can 20 acts in the direction in which the can 20 strongly bites the punch 10, the larger the stress, the more difficult the extraction of the can 20 becomes. In addition, one of the factors that determine the magnitude of residual stress in the circumferential direction is the strength of the material. In the case of steel D & I can, which is a material for steel D & I cans, since the strength is basically higher than that of aluminum, most steel D & I cans produced at present have a difference in degree, but a poor extraction, that is, rollback occurs.

(A) and (b) shown in Fig. 1F illustrate the outline of the can in which rollback occurred when the can was extracted from the punch. In the case of (a) in which rollback occurred, a part of the material on the top of the wall of the can 20 was torn, and the rolled form was shown at several places. In the case of (b), the top of the can 20 was pressed by the extractor 30. Wrinkles occur.

As such, due to the problem of rollback in the process of separating the can 20, a jamming occurs when the can 20 is transferred to a trimming process, which is a subsequent process, so that the machine stops during the continuous process. This is often the case, causing breakage of the trimming knife. As a result, there is a problem that causes time and money loss due to process delay and mechanical failure.

The present invention has been made to solve the above problems, an object of the present invention is to improve the problem that the separation of the can from the punch difficult due to the residual stress remaining in the body of the can after ironing and prevent the rollback of the can It is to provide an ironing punch to improve the extractability.

1a to 1e is a process diagram showing a can manufacturing process according to the prior art,

Figure 1a is a cross-sectional view showing a product molded by two-piece D & I can manufacturing process.

Figure 1b is a state diagram showing the advance stroke of the punch.

Figure 1c is a state diagram showing the reverse stroke and can extraction process of the punch.

1D is a detailed view of FIG. 1C.

1E is a front view of the extractor.

Figure 1f is an illustration showing the appearance of the can extracted by the prior art.

Figure 2 is a schematic diagram showing the outline of the ironing punch according to the present invention.

3a to 3c show the ironing punch is applied to the manufacturing process of the can

As a drawing,

3A is a partial sectional view showing a state after ironing.

Figure 3b is a partial cross-sectional view showing the bottom forming operation of the can.

Figure 3c is a detailed view showing the movement of the can wall material of the present invention.

Figure 4 is a view comparing the embodiment of the prior art and the present invention.

<Description of the symbols for the main parts of the drawings>

20: can 22: can wall portion

24: Can bottom part 26, 27, 28: 1st, 2nd, 3rd stage ironing die

30: extractor pieces: 32

42: groove portion D: groove depth

H: Finished can height I: Can wall thickness

L: Groove length N: Spacing (between grooves)

R: Curvature (both ends) S: Can radius

W: groove width

The present invention is configured as follows to achieve the above object. That is, in the conventional ironing punch used for can body shaping, the present invention has a depth of 2 to 8% of the finished can wall thickness, and a length of 8 to 16% of the finished can height. A concave groove portion having a width of 8 to 20% of the can radius is formed, and the groove portion has a curvature at both ends of 50% of the width, and a smooth curvature at the interface with the punch surface forms a circumference of the punch. Characterized in that the interval between the groove and the groove in the direction to be arranged 2 to 5 times the width of the groove portion.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a view illustrating an outline of the ironing punch according to the present invention, and FIGS. 3A to 3C are views showing the ironing punch applied to the can manufacturing process.

Referring to the drawings, the ironing punch 40 according to the present invention has a groove portion 42 which is elongated in the longitudinal direction, ie, in the axial direction, on the outer surface of a conventional punch. Here, the depth D of the groove 42 constitutes 2 to 8% of the wall thickness I of the finished can, but if smaller than the value, the effect of the groove 42 of the present invention is lost and vice versa. In this case, rather, the can 20 extraction performance is weakened.

On the other hand, the length (L) of the groove 42 makes up 8 to 16% of the height (H) of the finished can and the width (W) of the groove 42 is made of 8 to 20% of the can radius (S). Further, the curvature R at both ends of the groove 42 forms half of the width W of the groove 42, that is, 50%, and the interface between the surface of the ironing punch 40 and the groove 42 is smooth. It is treated with one curvature.

In addition, the grooves 42 are arranged in the circumferential direction of the ironing punch 40 so that the spacing N between the grooves 42 is two to five times the width W of the grooves 42. The ironing punches 40 are arranged in two rows in the longitudinal direction, that is, in the axial direction. The reason for defining the length, width, and number of the grooves 42 is that if the size is excessive, the height H of the finished can is lowered because the amount of material filled in the grooves 42 increases during the ironing process. There is a possibility, on the contrary, if too small, the result of not obtaining the effect of the groove 42 occurs. Therefore, the desired effect of the present invention can be expected only if it corresponds to the appropriate dimension value presented above.

Referring to the operation of the present invention having the configuration as described above are as follows.

First, Figure 3a is a view showing a state of completing the body molding of the can 20 by applying the ironing punch 40 according to the present invention. As shown in the drawing, when the ironing process is completed, the material forming the can 20 is filled in the concave groove 42 formed in the ironing punch 40. In the state in which the material of the can 20 is filled in the groove 42, it may be considered that the extraction operation will be difficult, but in the case of the bottom 20 of the can 20 performed in a conventional steel mill, which will be described later. The effect on the present invention will appear.

FIG. 3B illustrates a bottom forming operation of the can 20. In the bottom forming of the can 20, which gives the can bottom 24 a concave shape, the material, that is, the can wall part 22, moves in the direction of the arrow. ) Moves slightly toward the can 24. This phenomenon is commonly referred to as pull-down, which is a phenomenon that occurs during the manufacture of all D & I cans having concave dome shaped cans 24.

When such a pull-down phenomenon occurs, the can wall portion 22 leaves the groove portion 42 of the surface of the ironing punch 40 and the contact state with the surface of the ironing punch 40 is released as shown in FIG. 3C. Done. Therefore, in the conventional processing method, extraction of the raw material, that is, the can wall portion 22 and the ironing punch 40 while maintaining a strong contact state is performed, whereas most of the can wall portions 22 are extracted during the extraction according to the present invention. Since the ironing punch 40 is separated from the ironing punch 40 while the contact with the outer surface of the ironing punch 40 is released, the extraction performance is excellent and the extraction defect such as rollback is greatly reduced.

In addition, the body of the can 20 completed by the above method is advantageous in terms of stability of the can 20 because there is a portion in which the wall thickness I of the can 20 is reinforced in the middle.

Hereinafter, the effect will be described through comparative examples of the present invention and known technology.

Comparative Example

Fig. 4 shows the results of processing the steel D & I can with a conventional punch (X) and the result of processing with the ironing punch of the present invention (Y), respectively, with the vertical axis representing the material hardness and the horizontal axis representing the It shows rollback incidence according to material hardness.

First, in the present embodiment, the D & I can processing test was carried out on eight stone steel sheets in the hardness range of about 56 to 59, and the extraction performance under each condition was compared by measuring the rollback incidence rate. . Here, the rollback incidence rate is a value obtained by measuring the length of roll can occur at the top of the can and dividing it by the circumference of the can. When this value is 100%, it means that rollback has occurred in the entire circumference of the can.

In addition, the thickness of the steel plate applied in this test is 0.245mm, the radius (S) of the finished can is 33mm, the height (H) of the finished can is 132mm, the wall thickness (I) of the finished can is 0.082mm. The ironing punch 40 of the present invention used in the test has a depth of the groove portion 42 of about 3% of the finished can wall thickness (I), the length of the groove portion 42 is 10.2% of the height of the completion can (H), The width W of the groove 42 is 12.8% of the can radius S, the curvature R of both ends of the groove 42 is about four times the width W of the groove 42, and the ironing punch (40) Two rows of grooves 42 were arranged in the longitudinal direction.

As can be seen from the result shown in the figure, when the average punching rollback occurred about 25%, the ironing punch 40 according to the present invention had a rollback of about 7%. As a result, it can be seen that the rollback phenomenon of the can 20 is greatly reduced and the extraction performance is remarkably improved.

According to the present invention having the above-described configuration, it is possible to significantly reduce the rollback incidence occurred when processing with a conventional ironing punch can reduce the defective rate during can extraction, and also high-strength steel sheet and high strength during D & I can processing Since the workability can be improved also in the same material, time and economic effect can be aimed at.

Claims (2)

To improve the extraction performance of steel D & I cans, the depth is 2 to 8% of the finished can wall thickness, the length is 8 to 16% of the finished can height, and the width is the radius of the can on the outer circumferential surface of a conventional ironing punch. 8-20% of the concave grooves are formed, the grooves of which both ends have a curvature of 50% of the width, and the boundary between the grooves and the punch surface is formed with a gentle curvature to form the circumferential direction of the punch. Ironing punch for improving the extractability of the can, characterized in that the interval between each groove portion is arranged so as to be 2 to 5 times the width of the groove portion. 2. The ironing punch of claim 1, wherein the grooves are arranged in two rows in the longitudinal direction of the punch, that is, in the axial direction.