JPH0213292B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a pre-printing method for drawing materials, and more specifically, takes into account the anisotropy of radial elongation associated with the history of metal materials. , relates to a method of pre-printing on a draw-forming material in which a printed image with no errors and excellent circumferential linearity is displayed on a draw-forming can.

(Prior Art) Drawing forming of surface-treated steel plates such as tinplate and stain-free steel, and metal plates such as aluminum is widely used for manufacturing so-called seamless cans (two-piece cans). 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 elongate in the height direction of the body and contract in the circumferential direction. It is confirmed that there is.

For 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 drawn on an annular developed surface with squares corresponding to the grid lines. Paint by hand and create a plate for the flat material.

In addition, a technique has already been proposed in which a rectangular original is optically expanded into a ring shape for plate making. It is described that a plate with an annularly expanded image can be created by taking a photo of a mandrel, wrapping the shortened photo around a mandrel, and taking the photo again through a truncated conical mirror placed around the mandrel. . Furthermore, in Japanese Patent Publication No. 48-23455, a truncated conical prism having a hole in the center with an inner diameter that is approximately the same as the outer diameter of the can is prepared, a rectangular original is placed inside the hole, and an image of the original is transferred to the prism and the inner diameter of the can. It is described that a plate of an annular surface is created by photographing with a camera through a correction lens.

(Problems to be Solved by the Invention) However, the above-mentioned hand-drawing method requires the operator's skill to create the plate, and also requires a great deal of cost and time. The printed images reproduced in this paper are still not fully satisfactory in terms of accuracy and the like.

Furthermore, the latter optical conversion method not only requires troublesome operations and special optical equipment, but also makes it difficult to accurately reproduce fine halftone dot patterns due to aberrations in the optical system. Moreover, each time the original of the drawn body changes, a troublesome conversion operation must be performed to create a plate.

Furthermore, all metal materials for can making are made thinner by advanced rolling operations, and due to the influence of this rolling, anisotropy occurs in the plastic flow of the materials during drawing. For this reason, the printed image on the side wall of the resulting draw-formed can, particularly in the upper portion of the side wall, is likely to be disturbed, and the accuracy and linearity of the image may be impaired.

Therefore, an object of the present invention is to convert the image of a rectangular original into
Taking into account the anisotropy of plastic flow of metal materials and the anisotropy of radial elongation due to history, printing plates with annular development surfaces can be made finely and accurately in units of halftone dots or pixels. The object of the present invention is to provide a method for pre-printing a metal material for drawing forming, thereby forming a printed image on the circumferential side wall of a drawing object in accurate correspondence with the image of a rectangular original.

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 using 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.

Still another object of the present invention is to provide a method for preparing a pre-printing plate for drawing material, in which the above-mentioned conversion process can be quickly performed using a relatively small-capacity computer.

Still another object of the present invention is to form a draw-formed material in which a printed image with good accuracy and linearity is realized on the outer surface of the can side wall by pre-printing, despite the anisotropy of radial elongation due to rolling of the metal material. Provides a method for pre-printing materials for printing.

(Means for Solving the Problem) The present inventors converted an image to be printed on a document into a digital pixel signal on rectangular coordinates, and developed the rectangular coordinates into an annular surface having approximately the same area as the rectangle. The pixel signal on the rectangular coordinates is converted into a pixel signal or a group of pixel signals on the converted coordinates, and the pixel signal on the converted coordinates is converted into a pixel signal on the converted coordinates. By reading the signals in the order of coordinates and creating a material printing plate, the drawbacks of the above-mentioned conventional methods can be solved at once. It has been found that by pre-printing the material, a printed image with good precision and excellent linearity can be realized on the circumferential side wall of the draw-formed can.

In addition, the present inventors converted the image to be printed on a document into pixel signals on digital rectangular coordinates corresponding to pixels, and converted the rectangular coordinates to a circular surface with approximately the same area as the rectangle and a history of a metal material. Digital coordinates are converted to a surface corrected by the accompanying anisotropy of radial elongation, new coordinates of pixels existing in the gap between converted coordinates corresponding to adjacent pixels of rectangular coordinates are calculated, and new coordinates are calculated on the digital rectangular coordinates. The above-mentioned problem can also be effectively solved by substituting the pixel signals in the corresponding transformed coordinates and new coordinates, reading the pixel signals on the transformed coordinates in the order of the coordinates, and photoelectrically converting them to the printing plate. I discovered that.

That is, the present invention converts an image to be printed on a document into a digital pixel signal on rectangular coordinates in a pre-printing method on a metal material for draw forming, and converts the rectangular coordinates into a ring surface having approximately the same area as the rectangle. The pixel signal on the rectangular coordinates is converted into a pixel signal or a group of pixel signals of the converted coordinates by expanding the pixel signal into a pixel signal or a group of pixel signals of the converted coordinates and corresponding to the converted coordinates that are expanded and corrected by the anisotropy of radial elongation due to the history of the metal material. , there is provided a method for pre-printing a material for drawing forming, which is characterized in that a material printing plate is created by reading pixel signals on converted coordinates in the order of the coordinates, and this is used for printing the material.

According to the present invention, in the pre-printing method for drawing material, an image to be printed on a document is converted into pixel signals on digital rectangular coordinates corresponding to pixels, and the rectangular coordinates are converted into pixel signals having approximately the same area as the rectangle. The pixels existing in the gaps between the converted coordinates corresponding to adjacent pixels of the rectangular coordinates are converted into digital coordinates on the annular surface, which is also corrected by the anisotropy of radial elongation due to the history of the metal material. calculates the new coordinates of the digital rectangular coordinates, substitutes the pixel signals on the digital rectangular coordinates into the corresponding transformed coordinates and new coordinates, reads the pixel signals on the transformed coordinates in the order of the coordinates, and photoelectrically converts them to the printing plate. A method is provided, characterized in that a plate is used for printing a material.

(Function) In FIG. 1 showing a printed and drawn can, this printed and drawn can 1 consists of a bottom part 2 and a circumferential side wall part 3 that is seamlessly formed integrally with the bottom part 2. A printed layer 4 is provided on the side wall portion 3 . 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 the printing and drawing forming can 1, first, a printing layer is developed in a ring shape on a flat metal material 5 using a printing plate 6. 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 is held between a drawing die 13 having a diameter corresponding to the outside diameter of the molded body, and a blank having an outside diameter corresponding to the inside diameter of the molded body. The drawing punch 15 is pushed in to produce the drawing can 1 shown in FIG.

As already pointed out, in the portion that will become the circumferential side wall portion 3 of the drawn can 1, an elongated flow occurs in the height direction of the molded product, and a contractive flow occurs in the circumferential direction. These plastic flows do not occur uniformly over the entire surface of the metal material 5, and anisotropy is observed in the flows. FIG. 4 explains the anisotropy of the flow of the metal material 5. When manufacturing the metal material 5, the elongation is smallest in the rolling direction It is recognized that the largest elongation is shown in the direction Z that forms 45 degrees. Therefore, if the rectangular printing layer is simply converted to an annular printing layer and printing is performed on the metal material 5, 45
There will be a printed part that is greatly stretched and a printed part that is slightly stretched at every turn, and the printed image will be wavy and the linearity in the circumferential direction will not be maintained. Further, along with this variation in elongation, a positional shift of the printed image in the circumferential direction also occurs.

According to the present invention, from a rectangular printing original as shown in FIG. 2, a printing plate having an annularly developed printing image is created by taking into account the anisotropy of plastic flow shown in FIG. , created by digital image processing described below.

In the block diagram of FIG. 5 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; converts the pixel signal from the input scanning mechanism 17 from analog to digital and inputs it as a digital pixel signal, and performs corrections and cutting based on this digital pixel signal as necessary. , position designation, trimming; a plate-making computer 18 which is known per se and can perform editing operations such as compositing and convert digital pixel signals into digital/analog and output; Lower 1
output scanning mechanism 20 for manufacturing 9; recording material 21 for storing data from the plate-making computer 18; and digital pixel signals from the plate-making computer 18 from rectangular coordinates corrected for screen deviation during drawing forming. It consists of a transformation processing computer 22 that transforms the coordinates into annular coordinates having the same area as this and re-inputs the pixel signals on the transformed coordinates to the prepress computer 18.

(Description of First Embodiment) According to the present invention, a digital pixel signal on rectangular coordinates inputted to the plate-making computer 18 is converted into a ring shape having approximately the same area as the rectangle by a transformation processing computer. The pixel signals on the transformed coordinates are recorded as a pixel signal or a group of pixel signals on the transformed coordinates in correspondence with the transformed coordinates developed on a plane and corrected by the anisotropy of the elongation of the metal material, and the pixel signals on the transformed coordinates are read in the order of the coordinates.

Generally speaking, this process consists of (i) creation of a correspondence table between rectangular coordinates and annular transformation coordinates that takes into account the anisotropy of plastic flow during drawing, and (ii) conversion from rectangular coordinates based on the correspondence table. This is done through an operation of rewriting the coordinates.

In FIG. 6 for explaining the step (i) of creating a correspondence table, in step (a), image shift data is read into memory. In step (b), specify the size of the rectangle coordinates, that is, the number of vertical and horizontal pixels. Next, in step (c), a two-dimensional array (memory) of a size that can be accommodated when the rectangular coordinates are converted taking into account the image shift, is created.
Prepare (n, n). In step (d), coordinates are transformed from rectangular coordinates to an annular surface in consideration of the anisotropy of plastic flow during drawing. In Figures 7-A and 7-B for explaining this coordinate transformation, the transformed coordinates a', corresponding to the rectangular coordinates a, b (Figure 7-A),
b' (Figure 7-B) is the formula a'=γsinθ+O...(1) b'=γcosθ+O...(2) In the formula, a' and b' are each rounded integer values, and the 7th - The radius γ, angle θ, and center O in diagram B are calculated using the following formula. 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. 7-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.

Furthermore, during this coordinate transformation, it is also important to consider the anisotropy of plastic flow during drawing. In other words, elongation in the can axis direction (radial direction of the material) is maximum in the direction Z that is 45° away from the rolling direction mentioned above, and elongation is minimum in the rolling direction X or in a direction perpendicular to this. It is necessary to reduce the size of the printed image on the material in advance by an amount commensurate with the size of the image. For this purpose, for a large number of representative positions spaced at certain predetermined intervals on rectangular coordinates,
Image displacement data in the height direction and circumferential direction is prepared, and based on this image displacement data, the anisotropy of plastic flow is corrected during coordinate transformation.

This operation is performed according to the flowchart shown in FIG. That is, the coordinate values adjacent to each other in the X-axis direction of the rectangular coordinates are read, and it is determined whether these coordinate values are at a set position where anisotropy of plastic fluidity should be considered. If these coordinate values are outside the set positions, use the operations described above to →
′ and →′ coordinate transformations are performed. Increase the angle between ′ and ′ by a fraction of ′ (for example, 1/5) and calculate a new coordinate value ″ corresponding to this increased angle. If ′≠″, then ″ Let `` be ``, and calculate a new coordinate value corresponding to the increase in the angle described above. If ''=1, let `` be ``, and repeat the above 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).

If the read coordinate values are at the anisotropy consideration setting position, read the screen deviation data in the height direction and/or circumferential direction at each position, correct the rectangular coordinate values, and perform the coordinate transformation described above. .

Returning again to FIG. 6, in step (e), 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, 7-A and 7-
In diagram B, when converted into a→a′ and b→b′, A(a′, b′)←a*∈+b (where ∈ is 10 ^p when b is a p-digit number) is the number of ).

Steps (d) and (e) 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 Figure 9 for explaining the rewriting (ii) operation from 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), the previously created and saved correspondence table is read into each element of array A.

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 (g), 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 operation described above, the pixel signal [B (a, b)] on the rectangular coordinates is expanded to an annular surface having approximately the same area as this rectangle, and the elongation of the metal material is Correlate with the transformed coordinates corrected by anisotropy, transform into a pixel signal of the transformed coordinates or a group of pixel signals [C (a', b')], and read and output the pixel signals on the transformed coordinates in the order of the coordinates. It becomes possible to do so.

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.

(Description of the second aspect) In the second aspect of the present invention, the conversion coordinates that correct the elongation anisotropy of the material directly from the pixel signal on the rectangular coordinates without creating the above-mentioned correspondence table. The above pixel signal can be obtained.

According to this aspect of the present invention, the deformation processing computer 22 digitally transforms the rectangular coordinates into an annular surface having approximately the same area as the rectangle and modified by the anisotropy of elongation of the metal material. The new coordinates of the pixel existing in the gap between the transformed coordinates corresponding to adjacent pixels are calculated, and the pixel signal on the rectangular coordinates input to the plate-making computer 18 is substituted into the corresponding transformed coordinate and new coordinate. , reads and outputs pixel signals on the converted coordinates in coordinate order.

Flowchart 1 to explain this operation
In FIG. 0, first, in step (i), data is read from digital pixel signal data from the plate-making computer 18, and then in step (i).
In (ii), data adjacent to the data in the X-axis direction of the rectangular coordinates is read.

Regarding the data read in steps (i) and (ii), in step (iii) it is determined whether the rectangular coordinate values are at the anisotropy-considered setting position.
If the rectangular coordinate value is at the anisotropic consideration setting position,
In step (iv), screen displacement data in the height direction and/or circumferential direction at each position is read, rectangular coordinate values are corrected, and then coordinate transformation is performed in step (v). If the position is outside the set position considering anisotropy, coordinate transformation is directly performed in step (v).

That is, in step (v), coordinate transformations of data →' and →' are performed between the rectangular coordinates and the transformed coordinates converted into an annular surface having the same area as the rectangular coordinates, and the data of ' is recorded.

This coordinate transformation is performed by the means described with respect to Figures 7-A and 7-B. Each step is also 8th
It is similar to that shown in the figure.

In FIG. 10, if it is determined in step (ⓓ) that reading of the rectangular coordinate data has been completed, in step (),
Let the pixel coordinate in the vertical direction be y=1, and step (
), data whose Y coordinate is y is read out of the coordinate-converted and recorded data.

Next, in step ( ), the read data is sorted and recorded in ascending order of X coordinate (sort). In step (), it is determined whether or not the recording of the coordinate-transformed data has been completed. If it has not been completed, in step (), y=y+1 is set, and in step (), the data is read. Continue the operation.

In this way, the coordinate-converted data is input to the prepress computer 18 in the order in which it was recorded.

According to the present invention, by the operations described above, the pixel signals on the rectangular coordinates are expanded to a surface that is an annular surface having approximately the same area as this rectangle, and in which the anisotropy of plastic flow during drawing is corrected. It is possible to convert into a pixel signal or a group of pixel signals in the converted coordinates in correspondence with the converted coordinates at the time of conversion, 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.

(Description of Preferred Embodiments of the Invention) 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) A cylindrical scanning or plane scanning type is used that sequentially reads one line at a time, and the reading operation is performed by detecting reflected or transmitted light using a photomultiplier tube, phototransistor, 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 the Chromacom system (Rudolf Hell, West Germany), the Page Matsik system (Dainippon Ink & Chemicals), and the Sigmagraph system 2000 (Dainippon Screen Mfg.) may also be used.

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. Various methods can be adopted, such as diazo photography, dichromate gelatin plate making, electrolytic recording, discharge breakdown recording, current thermal recording, heat recording, pressure sensitive recording, and inkjet recording. The scanning methods include cylindrical scanning, rotating disk scanning, helical cylindrical scanning, belt-type plane scanning, multi-needle electrode plane scanning mechanical scanning; milled spot tube type, optical fiber tube type, and multi-needle electrode tube type. An electron tube scanning system such as the above; or a solid state scanning system such as a multi-needle electrode head system 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 characters, it is desirable that the range is 36 to 100 dots/mm.

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

In the present invention, the image shift data regarding rectangular coordinates is obtained by setting a range of positions on the rectangular coordinates in which the anisotropy of the plastic flow of the material during drawing is to be considered,
Positional deviation data within this setting range may be recorded in the internal memory or external memory of the deformation processing computer 22.

Among the circumferential side walls of the can, the degree of plastic flow is small in the part close to the bottom of the can, and the degree of plastic flow increases toward the top of the can edge, so generally the height on the rectangular coordinates is More than a quarter of the population, especially 3
If the position above 1/2 is set as the anisotropy-considered setting position, satisfactory results can be obtained in terms of preventing screen shift. Regarding the circumferential direction, the entire circumference can be set as an anisotropic consideration setting position. However, as shown in Figure 4, image shift occurs symmetrically about the axes X and Y, and also about the axis Z. If you prepare data with an angle within 45 degrees, you can use this data as image shift data over the entire circumference. The finer the interval between each position where image shift data is taken, the more accurately the anisotropy can be corrected, but on the other hand, a larger memory is required. In general, it has been found that satisfactory correction can be achieved if the interval on the rectangular coordinates of the image shift data is in the range of 0.1 to 2 mm, particularly 0.5 to 1 mm. Image misalignment data is obtained by printing on a flat metal material using a printing plate created from a rectangular original without considering the anisotropy of plastic flow, and then drawing the printed material. This can be easily obtained by wrapping a rectangular original around the circumferential side wall of a molded can and actually measuring the misalignment between the original and the printed image on the circumferential side wall.

The obtained image shift data can be repeatedly used regardless of the printing design, as long as a certain drawing process is performed on a certain metal material.

Metal materials for cans include untreated steel plates (black plates), various surface-treated steel plates, such as tin plated steel plates (tin plated), galvanized steel plates, aluminum plated steel plates, nickel plated steel plates, chrome plated steel plates, etc.; electrolytic chromic acid treatment Electrolytically treated steel plates such as steel plates; chemically treated steel plates such as phosphoric acid and/or chromic acid treated steel plates, light metal plates such as aluminum, or composites thereof, etc. are used.

The thickness of the base metal material varies depending on the final dimensions of the container and the type of material, but generally it is 0.1 to 0.5.
mm, preferably in the range of 0.2 to 0.35 mm.

For metal materials, paints with excellent processability and corrosion resistance, such as epoxy-phenol paints, epoxy-aminoplast paints, etc., are applied prior to printing.
Epoxy-acrylic paint, epoxy-vinyl paint, etc. can be applied, and the surface to be printed can be provided with a whiting paint made by blending titanium oxide or the like with the above-mentioned paint.

Printing can be performed by any printing method such as lithographic printing, offset printing, screen printing, gravure printing, letterpress printing, intaglio printing, electrophotographic printing, etc. using a plate manufactured by the method described above, and printing ink can be used as printing ink. Any printing ink or ultraviolet curing ink known per se may be used.

In order to obtain a drawing-formed can, the above-described printed metal material is punched into a shape such as a disk, and subjected to one-stage or multi-stage drawing between a drawing punch and a drawing die. The total drawing ratio, expressed as the ratio of the diameter of the material to the bottom diameter of the drawn container, is generally between 1.2 and 3.0, particularly 1.3.
It is desirable that it be within the range of 2.9 to 2.9.

According to the present invention, by the above-described method, the linearity of the printed image in the circumferential direction at the upper part of the side wall is such that the deviation between the rolling direction and the direction intersecting the same at 45 degrees is within 1% of the height of the side wall. The linearity of the printed image in the axial direction is maintained at a position approximately 22 degrees away from the rolling direction, and the deviation is 1% of the outer circumference of the side wall.
This results in a draw-formed printed can that is maintained within the following range.

(Operations and Effects of the Invention) According to the present invention, a computer converts the digital pixel signals of the rectangular original into the annular plane by using a computer, and the converted coordinates are By using a pixel signal of
It becomes possible to perform pre-printing with excellent fidelity and reproducibility on the drawing material, and it also becomes possible to significantly reduce the number of steps and processing time required to create a plate. Furthermore, during aperture processing, image distortion due to differences in direction can be completely addressed, making it easy to improve image quality. Furthermore, if a correspondence table to converted coordinates is created according to the first aspect of the present invention, the same type of can can be used even if the design or original is changed.
By reusing this, there is an advantage that rapid processing becomes possible.

Furthermore, by performing coordinate transformation according to the second aspect of the present invention, printing plates can be quickly created using a relatively small-capacity computer.

(Example) The invention is illustrated by the following example.

Example 1 A metal material shown in 5 in Figure 3-A having the following characteristics is prepared.

●Tein-free steel ●Tempering degree T-4CA ●Steel type Aluminum killed steel ●Thickness 0.21 (mm) Rectangular printing manuscript shown in Figure 2, here H=27.5
(mm), using a size of L = 206.25 (mm),
The input scanning mechanism shown at 17 in FIG.
The signal is input as a digital pixel signal to the plate-making computer shown in 8. A Chromagraph 299 scanner system is used as the input scanning mechanism, and a Response 320 system is used as the plate-making computer. In addition, the input digital image is
=990 (pixels) and L=7425 (pixels).

The input image data is output to a transformation processing computer shown at 22 in FIG. A Huacom M340S computer system is used as the computer for deformation processing. The computer performs coordinate transformation from rectangular coordinates to annular coordinates by the method shown in FIGS. 7, 8, and 10, taking into consideration the anisotropy of plastic flow during drawing. In Figures 7-A and 7-B for explaining this coordinate transformation, l=990, m=7425,
Let n=4300.

The coordinate-converted digital pixel signal is input again to the plate-making computer, and the process shown at 20 in FIG. 5 is performed.
Using the output scanning mechanism, a printing plate having an annularly developed image as shown in FIG. 4 is created in consideration of the anisotropy of plastic flow. ELP as output scanning mechanism
Use a laser plotter system.

Using the prepared printing plate, the above-mentioned surface of the metal material is printed by an offset printing method.

The printed metal material is punched into a circular blank with a diameter of 126.5 (mm) in the shearing process shown in Figure 3-B. Next, in the drawing process shown in FIG. 3-C twice, the drawing can shown in FIG. 1 is manufactured. The manufacturing conditions at that time were as follows.

●Wrinkle press pressure 4 (Kg/cm ² ) ●Drawing punch diameter 64.9 (mm) ●Drawing ratio 1.95 As mentioned above, this is the printed image on the side wall of the drawing can. The image misalignment with the rectangular printed original is maintained within 1% in the height direction of the can side wall between the rolling direction and the direction intersecting it at 45 degrees, and within 1% in the circumferential direction of the can side wall. A good draw-formed printing can was obtained that maintained the following properties.

Comparative example A printing plate was created using the same rectangular printing original on the surface of a metal material with the same characteristics, using the same method, but without taking into account the anisotropy of plastic flow during drawing, using the offset method. Print. The same drawing process as in Example 1 was carried out using the printed metal material.

As a result, the misalignment between the printed image on the side wall of the draw-formed can and the rectangular printed document was determined by the rolling direction.
Maximum of 7.2% in the height direction of the can side wall and 10% in the circumferential direction of the can side wall
, and clear distortion of the printed image was observed by visual inspection.

Example 2 A metal material shown in 5 in Figure 3-A having the following characteristics is prepared.

●Al-Mg-based aluminum alloy plate●Thickness 0.24 (mm) Using the above metal material, the following steps were carried out except that the wrinkle pressing pressure in the drawing process shown in Figure 3-C was 2 (Kg/cm ² ). A squeeze-printed can was manufactured in the same manner as in Example 1.

As a result, the misalignment between the printed image on the side wall of the draw-formed can and the aforementioned rectangular printed document was determined to be within 1% in the height direction of the can side wall between the rolling direction and the direction intersecting it at 45 degrees. A draw-formed printed can was obtained in which the amount was maintained within 1% in the circumferential direction of the side wall of the can.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing a printed and drawn product;
The figures are an expanded view of the circumferential side wall portion of the printed and drawn product in Fig. 1, Fig. 3-A, Fig. 3-B, and Fig. 3.
-C is an explanatory diagram for explaining the manufacturing process of the printed drawing-formed body shown in Fig. 1, and Fig. 4 is a plan view of a plate having a printed image taking into account the anisotropy of plastic flow in drawing. , FIG. 5 is a block diagram for explaining the image processing process, and FIG. 6 is a block diagram for explaining the image processing process.
Figures 7-A and 7-B for explaining the process of creating a correspondence table between rectangular coordinates and circular transformation coordinates
The figure is a diagram for explaining the coordinate transformation from rectangular coordinates to an annular surface, FIG. 8 is a flowchart for explaining the coordinate transformation operation taking into account the anisotropy of plastic flow, and FIG. FIG. 10, an explanatory diagram for explaining the rewriting operation from coordinates to transformed coordinates, is a flowchart for explaining coordinate transformation taking into account the anisotropy of plastic flow and reading of pixel signals from transformed coordinates. . 1 is a printing drawn product, 2 is a bottom portion, 3 is a circumferential side wall portion, 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)

[Claims] 1. In a pre-printing method on a metal material for drawing forming, an image to be printed on a document is converted into a digital pixel signal on rectangular coordinates, and the rectangular coordinates are converted into an annular shape having approximately the same area as the rectangle. Converting a pixel signal on a rectangular coordinate into a pixel signal or a group of pixel signals of a transformed coordinate in correspondence with a transformed coordinate that is developed on a plane and corrected by the anisotropy of radial elongation accompanying the history of the metal material, A method of pre-printing on material for drawing forming, characterized in that the pixel signals on the coordinates are read in the order of the coordinates to create a material printing plate for conversion, and this is used for printing the material. 2. In the pre-printing method on metal materials for drawing, the image to be printed on the document is converted into digital pixel signals on rectangular coordinates, and the rectangular coordinates are printed on an annular surface with approximately the same area as the rectangle, and on the metal material. The digital coordinates are converted to a surface corrected by the anisotropy of the radial elongation due to the history, and the new coordinates of pixels existing in the gaps between the converted coordinates corresponding to adjacent pixels of rectangular coordinates are calculated, and the digital rectangular coordinates are calculated. It is characterized by substituting the above pixel signals into the corresponding transformed coordinates and new coordinates, reading the pixel signals on the transformed coordinates in the order of the coordinates, photoelectrically converting them to a printing plate, and using this printing plate for printing the material. Pre-printing method for drawing material.