JPS6332381B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a truncated conical can body that is made from a can material that has been printed in advance through a molding process, and has a regular image without distortion on the can body. This invention relates to a method for manufacturing punched cans.

[Conventional technology]

Generally, cylindrical or frustoconical can products having a circular bottom wall and integral upright or sloped side walls are obtained by forming a flat metal stock in a drawing die. ing.

In this squeezing process, the side wall of the can is squeezed and distorted. Therefore, when molding a can having a can side with a desired image from a flat plate material that has been printed in advance before processing, in order to faithfully reproduce the image, the side wall after processing must be printed on the material before processing. It is practiced to print a distorted image such that a desired image is obtained at a desired position. For example, a rectangular image original is generally converted into a circular image original, as seen in the conical mirror method of Novlik Zannem (Norway), the circular prism method of Optelma (Switzerland), and the Prolex method of Prosystem (USA). The plan is to print this on a material board and then process it to obtain a can with the desired image on the side of the can. That is, as shown in FIG. 14, a rectangular original 1 having images X and Y (the bottom side of the can is indicated by b and the flange side is indicated by f) is converted into a circular original by the above-mentioned rectangular to circular original converting means (hereinafter referred to as A film-like circular document 2 with annularly distorted images X' and Y' due to D (called destruction)
This is then printed on a flat thin plate by any suitable known method to form the printed material 3. For example, this material is punched into a predetermined size using a punching/squeezing device (punching/squeezing die 4, punch 5) to obtain a primary squeezing material 6, which is then further punched using a suitable squeezing device (squeezing die 7, punch 8). A deep-squeezed can 9 with a desired image formed using
(referred to as DRD can) is obtained.

Normally, with these methods of converting rectangular originals to circular originals, it is impossible to distort originals with designs that are generally referred to as solid or continuous-tone designs that have not been subjected to halftone separation, which is important in printing technology. Although it is easy to do so, it is extremely difficult to warp a document with a so-called tone pattern, which is composed of extremely fine halftone dots after mesh resolution, into a circular shape.

After molding by the above molding method, in order to return the halftone dot array and halftone dot shape to their normal state, it is necessary to distort the disc-shaped state before molding to some extent. For this purpose, it is sufficient that the rectangular document before conversion has a regular halftone dot array and halftone dot shape.

However, with the above method, it is difficult to distort these halftone dots, so halftone separation necessary for printing technology is performed after the original is made into a circular document. exhibiting a condition. Therefore, the halftone dot array after molding is deformed, and the halftone dots themselves are also deformed, resulting in very poor printing reproducibility.

On the other hand, the method disclosed in "Method and Apparatus for Creating a Circular Image from a Rectangular Original" (Patent Application No. 59-98903, May 18, 1985) by Metal Boxes Ltd. (UK) is By combining the synchronized linear motion with the rotational motion of the film holder and the V-shaped photosensitive slit, it is possible to create not only solid (i.e., solid) patterns and continuous-tone patterns, but also halftone-tone objects composed of fine halftone dots. It has become possible to faithfully reproduce the design on products.

However, in any of the above-mentioned methods, each distortion method can ideally be applied only to punched cans formed into a cylindrical shape.

[Problem that the invention seeks to solve]

Therefore, other than punched cans that are formed into a cylindrical shape, for example, most of them are truncated conical punched cans with a taper angle in the range of 2° to 12.5°, or cans with stepped can bodies. In the case of press-forming, including punched cans formed in the shape of a truncated cone, the unfolded surface of the can body becomes fan-shaped, as shown in FIG. That is, in the figure, as in FIG. 14, a circular original 2 obtained by distortion processing of a rectangular original 1 having images X and Y is formed into a truncated conical punched can, and the can body is expanded. For example, the fan-shaped body 10 has a central angle θ ₀ , and for example, the rectangular images X and Y become distorted sectors X″ and Y″ with central angles θ ₁ and θ ₂ , respectively.
Therefore, there is a problem in that it is inconvenient to accurately display POS (Point of Sales) marks such as barcode marks, brand marks, parts of fair display, etc., where faithful reproduction of shapes is desired.

Therefore, in order to solve the above problems, the present invention creates a printing material board with a distorted print using a distortion original corrected in consideration of the curvature of a truncated conical punched can. An object of the present invention is to provide a method for manufacturing a truncated conical punched can in which a regular image is faithfully reproduced on the can body obtained by molding the can.

[Means for solving problems]

To achieve the above object, a method for manufacturing a truncated conical punched can according to the present invention, and in particular a method for displaying a regular image without distortion on a truncated conical punched can body from a pre-printed can stock. will be explained below with reference to the drawings.

As a method for correcting curvature distortion of a truncated conical punched can according to the present invention, in order to obtain a regular image on the can body after molding, a completed product of a truncated conical punched can having such an image is developed. As shown in FIG. 15, it has a fan shape with a central angle θ ₀ and is distorted by θ ₀ compared to the rectangular original 1. Therefore, we focused on the fact that in order to obtain regular images P and Q on the can body of a developed product, a design configuration as shown in FIG. 1, shown by P' and Q' having the same distortion on a rectangular document, is required. If you do this, the unfolded can body will look like the one shown in Figure 2, and the images P and Q will be close to normal.
is obtained.

FIG. 3 systematically shows the gist of the method for correcting curvature distortion of a truncated conical punched can according to the present invention, (1)
An original rectangular original 1 having regular images X and Y is converted into a fan shape using the distortion method described above. In this case, the original document is upside down. Next, (2) the necessary images X ₁ , Y ₁ obtained by sector transformation
Cut out. (3) Delete images X and Y from rectangular original 1. (4) A regular original 1'' is created by projecting the cut out fan-shaped converted images X ₁ and Y ₁ onto a rectangular original 1' from which the original image has been erased.

To describe one method for converting the rectangular original into a fan shape, the development angle θ ₀ of the can body of a truncated conical punched can generally corresponds to the original length l, which corresponds to 360° as shown in Figure 4. Another rectangular original 1 ₁ of length L is created, and the original rectangular original 1 of length l is incorporated into this. This rectangular original is converted into a circular ring shape as shown in FIG.
In this case, it is necessary to reverse the original document upside down (bottom side and flange side).

In FIG. 5, the necessary images X ₁ and Y ₁ are cut out from within the sector 11 of the hatched area obtained in this way,
Project onto regular original 1.

Next, (5) convert this truncated cone-shaped punched can body manuscript into a circular ring shape as in the conventional method using an arbitrary distortion method to create a circular manuscript 2';
By (6) transferring the image to a can stock plate and (7) forming it into a truncated conical punched can 12 by a known method, regular images X and Y can be obtained on the can body as shown in the figure. That is, (8) If the can body of this truncated conical punched can is developed, it will become a fan-shaped body with the regular image obtained in FIG.

[Effect]

In the above-described method for correcting curvature distortion of a truncated cone-shaped punched can, (1) a desired transformed image is finally formed by a sector transformation in which the regular image is turned upside down;
(2) to (4) By assembling these converted images into the original rectangular image, a rectangular regular original that can be distorted into a desired circular original before processing is created.

〔Example〕

In the method for manufacturing a truncated conical punched can according to the present invention,
An embodiment of a method for correcting curvature distortion of a truncated conical punched can will be described below.

FIG. 6 is a partial sectional view of an example 20 of a truncated conical punched can, showing its main dimensions, and FIG. 7 is a developed view of the can body of the truncated conical punched can, Composition limit x and print limit y are shown. Here H ₁ is the composition limit,
H ₂ indicates the distance from the flange side to the composition upper limit, and H ₀ indicates the distance from the bottom side to the composition upper limit.

(1) Prepare a straight line layout diagram (Figure 8) from the materials in Figures 6 and 7 by turning it upside down. Here, L ₀ =π(d ₁ +d ₂ )/2.

(2) Creating a manuscript for distortion correction Find the center angle θ ₂ of the developed can body of the desired can shape, and
L ₀ in the figure is compared with the reference dimension L and reduced to a ratio of θ ₂ /360. H ₁ , H ₂ , H ₀ are also reduced to the same ratio,
The distortion original shown in FIG. 9 is created by fitting it into the reference dimension L. For example, {H ₁ }=H ₁ ×θ ₂ /360 (3) Perform distortion for distortion correction.

Using the original shown in FIG. 9, distortion is performed with the flange side f facing inside and the bottom side b facing outside. As a result, the circular layout shown in FIG. 10 is obtained. In the figure, d is the effective maximum diameter of the distortion camera.

(4) The part (image) abba that requires distortion correction indicated by diagonal lines in the distortion film obtained by the distortion is enlarged to the same size as the rectangular layout diagram in Fig. 8 as shown in Fig. 11. do.

(5) Preparation of distortion manuscript (final distortion manuscript). As shown in FIG. 12, a new straight line design is constructed by assembling the images in FIG. 11 on the original straight line layout diagram (FIG. 8).

(6) This is enlarged or reduced as shown in FIG. 13 in accordance with the predetermined standard dimensions of the distortion method. Using the final distortion original created in this manner, a distortion film is then created in the conventional manner, and the desired can product is obtained by performing the circular original → transfer to a material → molding.

In addition to the method described above, image conversion using a computer such as the Response 300 series (owned by Toyo Seihan) by Cytecs (Israel) is also a method for converting a rectangular manuscript into a circular ring-shaped manuscript. Conceivable. However, these methods require a considerable amount of time and expense to develop the conversion software, and the resulting converted images are subjected to mesh decomposition after circular conversion, similar to the other methods mentioned above except for the method by Metalbox. Printing reproducibility is inferior to that of Metal Box's method.

〔Effect of the invention〕

The present invention provides a novel method for correcting curvature distortion of frusto-conical cans in particular in the image distortion step included in the method of manufacturing can bodies from pre-printed can stock. It is possible to obtain a desired truncated conical can product with a regular image without distortion on the can body from a can material that has been printed with a desired image using a distortion original. This has a remarkable effect on image formation that requires accurate display, such as a portion of the display.

[Brief explanation of the drawing]

FIG. 1 shows a rectangular original with the desired design for a truncated conical punched can; FIG. 2 shows an exploded view with the desired image of the can body of the truncated conical punched can; and FIG. 3 shows the present invention. FIG. 4 is a schematic diagram of a method for correcting curvature distortion of a truncated conical punched can, FIG. 4 is a schematic diagram of a method for converting a rectangular document into a fan shape, and FIG. 5 is a method for converting a rectangular document into a circular document. FIG. 6 is a partial sectional view of an embodiment of the truncated conical punched can; FIG. 7 is a developed view of the can body of the truncated conical punched can of FIG. 6; The figure shows the original for distortion correction, and Figure 9 shows the original for distortion.
Figure 0 is a circular layout, Figure 11 is an enlarged corrected image, Figure 12 is a straight line design, Figure 13 is the final distortion original with the straight line design corrected to a predetermined size, and Figure 14 is a preliminary image. FIG. 15, an example of a conventional manufacturing method for printed can products, shows an example in which the conventional pre-printed can manufacturing method is applied to a truncated conical punched can. 1... Original manuscript, 1... Regular manuscript, 2, 2 ₁ ... Circular manuscript, 3... Can material, 4, 5... Punching and squeezing device,
6... Primary squeezing material, 7, 8... Squeezing device, 9...
Deep squeeze can, 10... fan-shaped body, 11... fan-shaped, 12...
A truncated conical punched can, 20...A truncated conical punched can.

Claims (1)

[Scope of Claims] 1. A rectangular original having a regular image is turned upside down and converted into a fan shape, an inverted fan-shaped distorted image obtained by the above-mentioned inverted fan conversion is extracted, and the extracted fan shape is transferred to a plain rectangular original. A method for punching a truncated conical can, comprising the steps of: creating a corrected original by projecting a distorted image; converting the corrected original into a circular original; transferring the circular original onto a can material; and molding the can material. Production method. 2. The method for manufacturing a truncated conical punched can according to claim 1, wherein the plain rectangular original is obtained by erasing an original regular image from the rectangular original.