JPS6361657B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a method for producing a printed draw-formed product, and more specifically, the present invention relates to a method for producing a printed draw-formed product, and more specifically, a method for producing a pot-shaped container or cap by drawing from a flat material such as metal. The present invention relates to an improvement in a method for displaying an error-free printed image in the state of the drawn product by pre-printing the flat material on a portion corresponding to the side surface of the final drawn product. In particular, the present invention relates to a method in which a printing plate is created from a printing original by computer image processing.

Prior Art and Technical Problems of the Invention Drawing forming of surface-treated steel plates such as tinplate and stain-free steel, and metal plates such as aluminum is widely used in the production of so-called seamless cans (two-piece cans), metal caps, and the like. Painting or printing on each molded body after molding would complicate the operation, so it is desirable to paint or print the flat material in advance before drawing.

In this drawing process, the flat metal material undergoes plastic flow and becomes a pot-shaped compact. Considering the plastic flow in the part of the flat material that will become the circumferential side wall of the final drawn body, this part will expand in the height direction of the body and contract in the radial direction. It is confirmed that there is.

Regarding pre-printing on a flat material for drawing, it is necessary to convert the manuscript, which is rectangular in the unfolded state, into an annular plate, taking into consideration the plastic flow of the material mentioned above. A conversion method is known.

In a method called the hand-drawing method, a rectangular transparent document with grid lines is wrapped around the circumferential side wall of a drawn body, and an area corresponding to the image of the document is hand-drawn on an annular developed surface with squares corresponding to the grid lines. to create a plate for the flat material.
However, this method requires the skill of the operator to create the plate, and requires a great deal of cost and time, and the printed image that is actually reproduced on the circumferential side wall of the drawn product is not accurate. In this respect, I was still not fully satisfied.

A technique has already been proposed in which a rectangular manuscript is optically expanded into a ring shape to make a plate.
-Publication No. 11388 discloses that a rectangular original is photographed so as to be shortened in its height direction, the shortened photograph is wrapped around a mandle, and the photograph is taken again through a truncated conical mirror placed around this. describes the creation of a plate with an annularly developed image, and Japanese Patent Publication No. 48-23455 describes the preparation of a truncated conical prism with a hole in the center having an inner diameter that is approximately the same as the outer diameter of the can. , it is described that a rectangular original is placed on the inner surface of this hole, and an image of this original is photographed with a camera through the prism and a correction lens to create a plate having an annular surface.

However, these methods not only require troublesome operations and special optical equipment, but also have difficulty reproducing fine halftone dot patterns with high precision due to aberrations in the optical system. Moreover, each time the original document for the drawn body changes, a troublesome conversion operation must be performed to create a plate.

OBJECT OF THE INVENTION Therefore, an object of the present invention is to develop an image of a rectangular original in a fine and precise annular manner in units of pixels (halftone dots), taking into consideration the influence of plastic flow of waste material that occurs during drawing. To provide a method for manufacturing a drawn object, which can be made into a double-sided printing plate, thereby forming a defect-free printed image on the circumferential side wall of the drawn object in accurate correspondence with the image of a rectangular original. be.

Another object of the present invention is to provide a method for pre-printing a material for drawing forming, in which a planar plate developed into an annular shape from a rectangular printing original is created by digital computer image processing.

Still another object of the present invention is to simplify and speed up the digital image processing described above by utilizing a constant memory for draw-formed containers and caps of the same size, regardless of changes in original design. The object of the present invention is to provide a method for pre-printing a material for drawing to be performed.

Structure of the Invention According to the present invention, in a method for manufacturing a molded body of a printing press having a printed image on the side wall of the molded body by subjecting a pre-printed material to drawing forming, rectangular coordinates of original pixels are set to be approximately the same as the rectangle. Coordinate transformation is performed on the annular surface of the area to increase the number of pixels in the circumferential direction and decrease the number of pixels in the radial direction, and when the number of pixels increases, the transformation corresponds to adjacent pixels of rectangular coordinates. Calculates new coordinates of pixels that exist in the gaps between coordinates, creates a correspondence table between rectangular coordinates and circularly transformed coordinates, and photoelectrically scans the image to be printed on the original to generate digital pixel signals on the rectangular coordinates. Convert the pixel signals on the rectangular coordinates to the pixel signals on the circularly transformed coordinates based on the correspondence table and record them in memory, read the pixel signals on the circularly transformed coordinates in the order of the coordinates, and write the pixel signals on the material printing plate. A method is provided, characterized in that the printing plate is outputted and the printing plate is used as a material.

Effect When a flat material is drawn, a contraction flow occurs in the circumferential direction and an elongation flow occurs in the radial direction in the side wall portion.

In the present invention, the image of a rectangular original is converted into an annular developed surface in pixel units, and this conversion involves creating a correspondence table between rectangular coordinates and annular transformed coordinates in consideration of the plastic flow of the drawing process described above. This is performed by rewriting rectangular coordinates to circularly transformed coordinates based on a correspondence table.

When creating the correspondence table, the rectangular coordinates are converted into digital coordinates into an annular surface with approximately the same area as this rectangle, and at this time, the number of pixels is increased in the circumferential direction, and the number of pixels is decreased in the radial direction, and When increasing the number of pixels, new coordinates of pixels existing in gaps between transformed coordinates corresponding to adjacent pixels of rectangular coordinates are also calculated and used as circular transformed coordinates.

If the number of pixels in the circumferential direction is not increased, the printing plate on the annular developed surface will become a perforated image, and the negative effect of this perforated image will also appear on the printed image on the side wall of the drawn product. This inconvenience can be solved by calculating new coordinates of a pixel existing in a gap between transformed coordinates corresponding to adjacent pixels of rectangular coordinates, and by substituting a pixel signal into these new coordinates.

In the present invention, once the correspondence table is created,
By converting pixel signals on rectangular coordinates into pixel signals on circular transformation coordinates based on this correspondence table, and reading these in the order of the coordinates to create a printing plate, the influence of plastic flow of the material that occurs during drawing can be reduced. In consideration of this, an image of a rectangular original can be made into a printing plate with an annular development surface in fine detail and precision in pixel units.

In addition, although a certain amount of memory is required to create the correspondence table, the conversion from pixel signals on rectangular coordinates to pixel signals on circular transformation coordinates is performed simply by rewriting, making image processing easy and fast. At the same time, for containers and caps made by drawing of the same size, regardless of the change in document size,
The memory can be used repeatedly.

PREFERRED EMBODIMENTS OF THE INVENTION The invention will be explained in detail below based on specific examples shown in the accompanying drawings.

In FIG. 1 showing a printed and drawn product, this printed and drawn product 1 consists of a bottom portion 2 and a circumferential side wall portion 3 that is integrally formed with the bottom portion 2 without a seam. is provided with a printing layer 4. In FIG. 2, which shows the circumferential side wall 3 developed, it will be understood that the printed layer 4 has a rectangular shape with a length L and a height H.

In Figures 3-A to 3-C for explaining the manufacturing process of this printed drawing-formed body 1, first, using a printing plate 6 on a flat metal material 5, a printing layer is developed into an annular shape. 7 (Figure 3-A). This annular printed layer 7 has an inner circumferential portion 8 approximately equal to the length L of the rectangular printed layer 4, an outer circumferential portion 9 which is larger than the length L, and a difference D between the outer circumferential radius and the inner circumferential radius. It is smaller than the height H of the rectangular printed layer 4, and the rectangular printed layer 4 and the annular printed layer 7 have substantially the same area. The printed metal material 5a is cut into a circular blank 12 using a combination of a shearing die 10 and a shearing punch 11 in the shearing process shown in FIG. 3-B.
Punch out. Next, in the drawing step shown in FIG. 3-C, the circular blank 12 is sandwiched between a drawing die 13 having a diameter corresponding to the outside diameter of the molded body and a wrinkle presser 14, and the circular blank 12 having an outside diameter corresponding to the inside diameter of the molded body. The drawing punch 15 is pushed in to produce the drawn body 1 shown in FIG. 1.

According to the present invention, a printing plate having an annularly expanded printing image is created from a rectangular printing original as shown in FIG. 2 by digital image processing described in detail below.

In the block diagram of FIG. 4 for explaining the process of this image processing, the apparatus used for this processing is, roughly speaking, a rectangular document 16.
An input scanning mechanism 17 for converting the image into an electrical signal; the pixel signal from the input scanning mechanism 17 is converted from analog to digital and input as a digital pixel signal, and if necessary, correction, cutting, and positioning are performed based on the digital pixel signal. A computer 18 for plate making known per se that can perform editing operations such as designation, trimming, and compositing, as well as output digital/analog conversion of digital pixel signals;
An output scanning mechanism 20 for producing printing plates or master plates 19 using electrical signals from; a recording material 21 for storing data from the plate-making computer 18; and digital pixel signals from the plate-making computer 18. It consists of a transformation processing computer 22 that transforms the coordinates from rectangular coordinates to annular coordinates having the same area as the rectangular coordinates and re-inputs pixel signals on the transformed coordinates to the prepress computer 18.

The input scanning mechanism 17 may be any known input mechanism, for example, one that reads one line of a document in the X-axis direction (main scanning), then shifts the position in the Y-axis direction (sub-scanning) and sequentially reads one line at a time. A cylindrical scanning or plane scanning type is used, and the reading operation is performed by detecting reflected or transmitted light using a photomultiplier tube, a phototransistor, a charge coupling device, etc. in general,
For multicolor originals, the colors are separated into cyan, magenta, yellow, and black, and input scanning is performed. Also,
The number of scanning lines can be changed for picture originals and text originals. Such devices are widely marketed under the name of scanners and are easily available.

The prepress computer 18 is a central processing unit (CPU) that accepts input/output commands, analyzes them, executes various programs, controls input/output devices, etc.
It is equipped with a terminal device that issues commands to the central processing unit (CPU), and a station that performs image processing and editing, as well as a disk drive used to store the system and various files, and a disk drive used to store the system and various files. Equipped with a magnetic tape device used for backup and restoration. A suitable example of such a prepress computer is one commercially available from Cytecs of Israel as the Response 300 series, but the present invention is not limited thereto, and similar computers may be used. For example, studio
800 series (Crossfield, UK),
Plate-making computers such as Chromacom System (Rudolf Hell & Co., West Germany), Pagematsch System (Dainippon Ink & Chemicals), and Sigmagraph System 2000 (Dainippon Screen Manufacturing) may also be used.

According to the present invention, the transformed coordinates are obtained when a digital pixel signal on rectangular coordinates input to the plate-making computer 18 is expanded by the transformation processing computer into an annular surface having approximately the same area as the rectangle. A pixel signal or a group of pixel signals on the transformed coordinates is recorded in correspondence with the pixel signals on the transformed coordinates, and the pixel signals on the transformed coordinates are read in the order of the coordinates.

Generally speaking, this processing is performed through (i) creation of a correspondence table between rectangular coordinates and circularly transformed coordinates, and (ii) rewriting from rectangular coordinates to transformed coordinates based on the correspondence table.

In FIG. 5 for explaining the step (i) of creating a correspondence table, in step (a), the size of rectangular coordinates, that is, the number of vertical and horizontal pixels is specified. Next, in step (b), a two-dimensional array (memory) A(n, n) of a size that can be accommodated when the coordinates are transformed in the same area as the rectangular coordinates is prepared. In step (c), coordinate transformation from rectangular coordinates to an annular surface is performed. The sixth part to explain this coordinate transformation is
- In Figure A and Figure 6-B, rectangular coordinates a, b
(Fig. 6-A) and the corresponding transformed coordinates a', b' (Fig. 6-A)
Figure B) is the formula a' = γ sin θ + O ... (1) b' = γ cos θ + O ... (2) In the formula, a' and b' are each rounded integer values, and the radius γ in Figure 6-B is , angle θ and center O are the following formulas θ=2πb/m...(4) The value is determined to satisfy .

At the time of this coordinate transformation, it is necessary to consider the influence of plastic flow during drawing of the flat material.
That is, in the annular surface shown in Fig. 6-B, since contraction flow occurs in the circumferential direction and stretching flow occurs in the radial direction during drawing, the number of pixels is increased in advance in the circumferential direction during coordinate transformation. , it is necessary to reduce the number of pixels in the radial direction.

This operation is performed according to the flowchart shown in FIG. That is, the coordinate values adjacent in the X-axis direction of the rectangular coordinates are read, and the →' and →' coordinate transformations are performed by the operations described above. ′
and ′ by dividing the angle by a fraction of ′ (for example, 1/
5), and calculate a new coordinate ``corresponding to the increment in this angle. If ``≠'', `` is set to ``, and a new coordinate value corresponding to the increase in the angle described above is calculated. If ''=1, set , and repeat the above-mentioned operation. In this way, the correspondence between the coordinate values of the rectangular coordinates and the group of coordinate values in the transformed coordinates is easily performed. The reduction of the coordinate values in the radial direction is easily performed because a plurality of coordinate values of the rectangular coordinates correspond to one coordinate value of the transformed coordinates (later entered data is stored).

Returning again to FIG. 5, in step (d), the original rectangular coordinate values are substituted into the elements of the array A that correspond to the coordinate values obtained by the conversion. That is, No. 6-A and 6-
In diagram B, when converted to a → a' and b → b', A (a', b') ← a * ε + b (however, ε is a number of 10 ^p when b is a number of P digits) is a number).

Steps (c) and (d) are performed for all coordinate values of the rectangular coordinates.

Finally, the obtained two-dimensional array A(n, n) is recorded on an external storage device such as a magnetic disk, and the process of creating the correspondence table is completed. In the present invention, once the operation of creating the correspondence table is performed, the same drawn product can be used repeatedly regardless of changes in the original or design.

In Fig. 8 for explaining the operation (ii) of rewriting rectangular coordinates to converted coordinates based on the correspondence table formed in this way, in step (a), the size (number of vertical and horizontal pixels) of the rectangular original is two-dimensional array (memory),
Prepare B(l,m).

Next, in step (b), a two-dimensional array (memory), A(n,
n) is prepared, and in step (c), a two-dimensional array C(n, n) for rewriting is prepared.

In step (d), pixel signals of the rectangular original from the plate-making computer are read into each element of array B. In step (e), each element of array A of the correspondence table created and saved previously is read.

In step (f), for each element of array A in the correspondence table, the pixel signal of the element of array B that corresponds to the assigned rectangular coordinate value is assigned to the element of array C that is equal to the element number of array A. That is, the correspondence table A(a′,
As mentioned above, the rectangular coordinates assigned to b′) are
(a, b), but the pixel signal is C(a', b')←B
It will be substituted in the form (a, b). Process (f)
By making the elements of array B correspond to all the elements of array A, a pixel signal converted to array C is obtained.

Finally, in step (e), the transformed coordinates obtained in the array C are read in coordinate order and rewritten for input to the prepress computer 18.

According to the present invention, by the operations described above, the pixel signal [B (a, b)] on rectangular coordinates is converted into a corresponding one by the converted coordinates when the rectangular coordinates are expanded into an annular surface having approximately the same area as this rectangle. This makes it possible to convert the converted coordinates into a pixel signal or a group of pixel signals [C(a', b')], and to read and output the pixel signals on the converted coordinates in coordinate order.

The pixel signals on the converted coordinates are supplied to the output scanning mechanism 20 in coordinate order, and a printing plate or block copy is created. The output scanning mechanism 20 may be any scanning recording method known per se, such as silver halide photography, dry silver recording, electrophotography, electrostatic recording, negative or positive photoresist recording, or photopolymer recording. A variety of methods can be employed, including the method, diazo photography, dichromate gelatin plate making method, electrolytic recording method, discharge breakdown recording method, current-carrying thermal recording method, heat-sensitive recording method, pressure-sensitive recording method, and inkjet recording method. The scanning methods include mechanical scanning such as cylindrical scanning, rotary plate scanning, helical cylindrical scanning, belt type plane scanning, multi-needle electrode plane scanning; milled spot tube type, optical fiber tube type,
Electron tube scanning such as a multi-needle electrode tube type; or solid-state scanning such as a multi-needle electrode head type is used.

Among these various recording methods, the present invention has the advantages of concentrating optical energy in a minute area on the order of a wavelength, scanning a wide range of light beams, and quickly turning on and off the original. It is preferable to use a laser recording method for reading and printing. As a laser light source,
He-Ne laser, Ar laser, He-Cd laser, etc. are used.

In the present invention, the pixel density in the rectangular coordinates and the final transformed coordinates can be varied over a wide range as desired, but generally speaking, it is desirable to use within the range of 12 to 100 dots/mm; However, in the case of patterns, the range of 12 to 14 dots/mm,
In the case of letters and letters, it is desirable that the range is 36 to 100 dots/mm.

The output scanning mechanism 20 allows cyan, magenta,
Yellow and black plates can be produced directly and used for printing materials, or negatives can be produced once and then reverse baked to produce printing plates.

Effects of the Invention According to the present invention, when a digital pixel signal of a rectangular original is transformed into a pixel signal of transformed coordinates by coordinate transformation to an annular plane, this processing operation is performed by creating a correspondence table between rectangular coordinates and annular transformed coordinates. This is performed by rewriting the rectangular coordinates to converted coordinates based on the correspondence table. Moreover, when creating the correspondence table, the coordinates of the rectangle are converted to an annular surface having approximately the same area as the rectangle so that the number of pixels increases in the circumferential direction and decreases in the radial direction. When increasing, new coordinates of pixels existing in the gap between transformed coordinates corresponding to adjacent pixels of rectangular coordinates are calculated, and a correspondence table between rectangular coordinates and circular transformed coordinates is created from this. Taking into consideration the effects of plastic flow of the material that occurs during drawing, the image of a rectangular original can be made into a printing plate with an annular development surface finely and precisely in pixel units. Accordingly, there is an advantage that a defect-free printed image can be formed on the circumferential side wall of the drawn body.

In addition, although a certain amount of memory is required for the correspondence table, the conversion from pixel signals on rectangular coordinates to pixel signals on circular transformation coordinates is performed simply by rewriting, making image processing easy and fast. In addition, there is an advantage that the memory can be used repeatedly for draw-formed containers or caps of the same size, regardless of changes in document size.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing a printed and drawn product;
The figure is an expanded view showing the circumferential side wall of the printed and drawn body shown in Figure 1, and Figures 3-A to 3-C illustrate the manufacturing process of the printed and drawn body shown in Figure 1. FIG. 4 is a block diagram for explaining the image processing process. FIG. 5 is a diagram for explaining the process of creating a correspondence table between rectangular coordinates and circular transformation coordinates. -Figure A and Figure 6-B are
FIG. 7 is a flowchart for explaining the coordinate conversion operation. FIG. 8 is a diagram for explaining the rewriting operation from rectangular coordinates to converted coordinates. The figure is shown below. 1 is a printing drawing formed body, 2 is a bottom part, 3 is a circumferential side wall part, 4 is a printing layer, 5 is a metal material, 6 is a printing plate,
7 is a printed layer developed in an annular shape, 8 is an inner periphery, 9 is an outer periphery, 10 is a shearing die, 11 is a shearing punch,
12 is a blank, 13 is a drawing die, 14 is a wrinkle presser, and 15 is a drawing punch.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a printed and drawn body having a printed image on the side wall of the formed body by subjecting a pre-printed material to drawing forming, wherein the rectangular coordinates of the document pixels are set to an annular shape having approximately the same area as the rectangle. Digital coordinate conversion is performed on the surface to increase the number of pixels in the circumferential direction and decrease the number of pixels in the radial direction, and when the number of pixels increases, the conversion coordinates corresponding to adjacent pixels of rectangular coordinates are converted. calculates the new coordinates of the pixels existing in the gap between the two, creates a correspondence table between rectangular coordinates and circularly transformed coordinates, photoelectrically scans the image to be printed on the document and converts it into digital pixel signals on the rectangular coordinates. Then, the pixel signals on the rectangular coordinates are converted to the pixel signals on the circularly transformed coordinates based on the correspondence table and recorded in the memory, and the pixel signals on the circularly transformed coordinates are read in the order of the coordinates and output to the material printing plate. , a method characterized in that this printing plate is used for printing a material.