JP2555697B2 - Thin-walled draw-formed printing can and its manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thinned draw-formed printing can and a method for producing the same, and more specifically, to a thin-walled side wall portion obtained by drawing-redrawing from a preprinted metal material. The present invention relates to a printed can and a method for producing the same, in which a printed image of a document is faithfully reproduced.

(Prior Art) Surface-treated steel sheets such as tin and tin-free steel and drawing of metal sheets such as aluminum are widely used for manufacturing so-called seamless cans (two-piece cans). It is desirable to apply coating and printing to the flat plate-shaped material in advance prior to the draw forming, because painting and printing on individual molded articles after forming complicate the operation.

U.S. Pat. No. 4,692,810 proposed by the present inventors (JP-A-61-267053, 61-267763 and 62-9303)
No. 0), an image to be printed on a document is converted into digital pixel signals on rectangular coordinates, and image processing is performed to develop the digital pixel signal on an annular surface having substantially the same area as the rectangle, thereby forming a printing plate. It is described that a metal material to be drawn is preliminarily printed using this printing plate prepared.

(Problems to be Solved by the Invention) According to the method of the prior art, it is possible to make an image of a rectangular original document finely and accurately in units of halftone dots or pixels on a printing plate having an annular development surface. However, there is a limitation that the object is limited to a normal draw-formed can.

On the other hand, it is already known that, at the time of drawing-redrawing forming of a coated metal plate, the curvature corner portion of the redrawing die is formed into a deep drawing cup having a small diameter, and the side wall portion is bent and deformed to be thinned. However, a method of preprinting a metal material to be used in the production of the thin-walled draw-formed can so that a printed image faithful to the original image is displayed on the side wall of the can is not yet known.

Therefore, an object of the present invention is to provide a person who can manufacture a thinned draw-formed printing can in which a printed image corresponding to an image of a rectangular original is formed on a peripheral side wall portion from a preprinted metal material. is there.

Another object of the present invention is to take an image of a rectangular original into consideration for the side wall portion being stretched in the height direction by drawing and redrawing, or in consideration of the anisotropic fluidity of the metal material. The present invention provides a method for producing a thin-walled squeeze-molded printing can in which a side wall portion is stretched and a printed image that is faithful to the original is embodied even when the wall thickness is reduced. It is in.

Still another object of the present invention is to draw a preprinted metal material.
Even though it is formed by redrawing, it is highly drawn and the side wall is made thin, and the printed image on the side wall is suppressed to a level where the deviation is small even in the upper part where the degree of deformation is high. The present invention is to provide a chemical draw forming printing can.

(Means for Solving the Problems) According to the present invention, in a method for producing a draw-formed print can having a print image on a side wall of the can, which is formed by subjecting a preprinted metal material to draw forming. For the printed document, make sure that the reduction ratio in the height direction is approximately equal to the ratio of the average thickness of the side wall of the final can (t _W ) / the bottom thickness of the final can (t _B ), and reduce the pixel size. Reduced digital image processing for erasing corresponding rows on average is performed, and at the same time as or subsequently to this, image processing for developing the reduced processed document image on an annular surface having an area approximately the same as the area of the reduced processed document image is performed. After making a printing plate by doing, print on the material using this printing plate, after molding the printed metal plate into a front draw cup, this front draw cup,
Provided is a method for producing a thin-walled draw-molded printing can, which is characterized in that a redraw die having a small curvature is used to cause bending and debending deformation, thereby thinning a side wall portion.

According to the invention, there is also provided a method for producing a draw-formed printing can having a printed image on a side wall of the can, which comprises subjecting a preprinted metal material to draw forming, wherein a rectangular printing original is reduced in the height direction. The rows corresponding to the reduced portion of the pixels are deleted on average so that the ratio is approximately equal to the ratio of the average thickness of the side wall of the final can body (t _W ) / the bottom thickness of the final can body (t _B ). A surface that has undergone reduced digital image processing, and at the same time as or subsequently to this, a reduction-processed original image which is an annular surface having an area approximately the same as the area of the reduction-processed original image and which has been corrected by the anisotropy of elongation of the metal material A printing plate is created by performing image processing for development, printing is performed on the material using this printing plate, the printed metal plate is molded into a front squeezing cup, and then this front squeezing cup is
Provided is a method for producing a thin-walled draw-molded printing can, which is characterized in that a redraw die having a small curvature is used to cause bending and debending deformation, thereby thinning a side wall portion.

(Operation) Referring to FIG. 1 showing a thinned draw-formed printing can of the present invention, the thin-walled drawn printed can 1 comprises a bottom portion 2 and a circumferential side wall portion 3 which is integrally formed integrally with the bottom portion 2. And consists of. This circumferential side wall 3 is highly squeezed, and the ratio (H / D) of can height (H) to can diameter (D) is generally 1.0 to 4.
0, in particular 1.0 to 3.0, moreover the side wall portion 3 is stretched to have been thinned, the ratio of the side wall thickness (t _W) and the bottom thickness _{(t B) (t W /} t B) is It is generally 0.4 to 1.0, particularly 0.6 to 1.0.

A printing layer 4 is provided on the side wall portion 3 by preprinting. In FIG. 2 showing the circumferential side wall portion 3 in a developed state,
The print layer 4 has a rectangular shape with a length of 1 and a height of h, and the lower reference displacement amount in the upper portion 5 of the print layer 4 is 3.0 in the axial direction.
% Or less, especially 2.5% or less, and 2.0% or less in the circumferential direction, especially
It is less than 1.5%.

Here, the shift amount is a shift amount in a normal meaning, that is, an amount (absolute value) defined by the following formula.

In FIGS. 3A to 3D for explaining the manufacturing process of the thinned draw-formed printing can 1, first, a printing plate 7 is used for a flat plate-shaped coated or unpainted metal material 6,
The printing layer 8 developed in a ring shape is applied (FIG. 3-A). In the annular print layer 8, the inner peripheral portion 9 is substantially equal to the length 1 of the rectangular print layer 4, the outer peripheral portion 10 is larger than the length 1, and the difference m between the outer peripheral portion radius and the inner peripheral portion radius is It is smaller than the height h of the rectangular print layer 4, and the area of the annular print layer 8 is reduced so as to be smaller than the area of the rectangular print layer 4. The degree of reduction of the area corresponds to the degree of thinning of the side wall portion 3 (detailed later).

The printed metal material 6a is punched into a circular blank 13 using a combination of a shearing die 11 and a shearing punch 12 in a shearing step shown in FIG. 3-B. Next, in the pre-drawing step shown in FIG. 3-C, a circular blank is formed between the pre-drawing die 14 having a diameter larger than that of the final molded body and the wrinkle retainer 15.
Insert the front squeeze punch 17 with the 13
To manufacture. Finally, in FIG. 3-D showing the redrawing process, the front drawing cup 17 is held by the annular holding member 18 inserted in the cup and the redrawing die 19 located therebelow, and the inside of the holding member 18 is held. The re-drawing punch 20 provided so as to be able to move in and out is pushed in. The front drawing cup 17 passes through a horizontal plane defined by the annular bottom surface 21 of the annular holding member 18 and the upper surface 22 of the redrawing die 19, and is bent almost perpendicularly to the axial direction by the action corner portion 23 of the redrawing die 19 having a small curvature. Then, the final formed body having a small diameter is deep-drawn and, at the same time, the side wall is thinned by bending and debending deformation.

According to the present invention, a rectangular printing original as shown in FIG. 2 is reduced or further reduced in consideration of the fact that the side wall portion is stretched and thinned in the height direction by drawing and redrawing. In consideration of the anisotropy of elongation of the metal material, a printing plate having a print having a print image developed in a ring shape is prepared by digital image processing described below.

In the block diagram of FIG. 4 for explaining the steps of this image processing, the apparatus used for this processing is roughly the input scanning mechanism 25 for converting the image of the rectangular original 24 into an electric signal; The pixel signal from the input scanning mechanism 25 is analog-to-digital converted and input as a digital pixel signal, and if necessary, based on the digital pixel signal, editing operations such as correction, cutting, position designation, trimming; combining, etc. are performed, and A known plate making computer 26 capable of converting digital pixel signals into digital / analog signals and outputting them; an output scanning mechanism 28 for producing a printing plate or a block 27 by an electric signal from the computer 26; a plate making computer The recording material 29 for storing the data of 26; and the digital pixel signal from the plate-making computer 26, and the extension that occurs during redraw forming. Corresponding to (thinning), the reduction processing digital pixel signal is reduced in the height direction of the original image, and the reduction processing digital pixel signal is changed from the reduction rectangular coordinate to an annular coordinate having the same area (this annular coordinate is an anisotropic expansion of the metal material). It may be modified according to the characteristics) and the transformation processing computer 30 for re-inputting the pixel signal on the transformed coordinates to the plate making computer 26.

According to the present invention, the digital image processing is performed by the deformation processing computer 30 as follows. First, in the flow chart of FIG. 5 for explaining this processing operation, in step (i), the plate making computer 26
Read digital image signal data from. Next, in step (ii), one row of pixels is deleted for each reduction ratio to reduce the image in the height direction.

In FIGS. 6-A and 6-B for explaining this reduction processing, the original rectangular coordinates a, b (FIG. 6-A) and the corresponding reduced rectangular coordinates a ′, b ′ (FIG. 6-B) ) Is the expression b ′ = b (2) where a ′ and b ′ are integer values rounded off by rounding, l ₀ is the height of the original rectangular coordinate, and l is the reduced rectangular coordinate. The height of is determined so as to satisfy. In this reduction process, the area of the original rectangular coordinate is S ₀ , the area of the reduced coordinate is S, the bottom thickness of the final can is t _B , and the average thickness of the side wall is t _W. And the value to be reduced can be easily determined. The reduction processing is performed by erasing the l ₀ -l rows of pixels on average.

Returning to FIG. 5, in step (iii), data is read from the digital pixel signal data of the reduced rectangular original, and in step (iv), data adjacent to the data in the X-axis direction of the reduced rectangular coordinate is read. .

Regarding the data and the data read in steps (iii) and (iv), in step (V), data → ′ and data between the reduced rectangular coordinates and the transformed coordinates converted into an annular surface having the same area as the reduced rectangular coordinates. → Perform the coordinate transformation of ′ and record the data of ′.

7-A and 7-B for explaining this coordinate transformation
In the figure, the reduced rectangular coordinates a ', b' (FIG. 7-A) and the corresponding converted coordinates a ", b" (FIG. 7-B) are expressed by the formula a "= γsinθ + O (4) b". = Γcosθ + O (5) In the formula, a ″ and b ″ are integer values rounded off by rounding off, respectively, and the radius γ, the angle θ, and the center O in FIG. It is determined so that the value of

At the time of this coordinate conversion, it is necessary to consider the influence of plastic flow at the time of drawing the flat plate material. That is, 7th
In the annular surface shown in FIG. B, contraction flow in the circumferential direction and expansion flow in the radial direction occur during drawing-redrawing, respectively. It is necessary to reduce the number of pixels in the direction.

This operation is performed after step (vi) in FIG. That is, first, in step (vi), it is determined whether or not the data adjacent to each other in the X-axis direction of the reduced rectangular coordinates are two points of continuous colors. If and are two points of continuous color, step (Vi
In i), according to the principle shown in FIGS. 7-A and 7-B,
Between ′ and ′, the angle is divided by a fraction of ′ (eg 1 /
5) Increase by only and calculate new coordinate value ″.

Then, in step (Viii), the new coordinate value ″ is compared with the converted coordinate value ′, and if ≠≠, in step (iX) ″ is recorded and the new coordinate value ″ is substituted for ′. Then, in step (Vii), a new coordinate value corresponding to the new increment of the angle is calculated, and thereafter, this operation is similarly repeated until ′ = ″.

In step (Viii), if the new coordinate value ″ is “=”, the rectangular coordinate data is set in step (X), and the rectangular coordinate data reading is completed in step (Xi). If it is not finished, in step (iV), new data is read and the above-mentioned operation is repeated. In step (Vi), when it is determined that the data and the data are not two continuous colors, the data is read and the next data is read.

Thus, according to the present invention, the reduced rectangular coordinate value and the annular surface transformed coordinate value are easily associated with each other, and the new coordinate of the pixel existing in the gap between the two transformed coordinate positions obtained by this association is easily obtained. The calculation can be easily performed, and the pixel signal on the rectangular coordinate can be substituted on the converted coordinate or further on the new coordinate to increase the data in the circumferential direction in advance. Further, the reduction of the coordinate value in the radial direction is easily performed because the data of a plurality of coordinate values of the rectangular coordinate corresponds to one coordinate value of the converted coordinate (data entered later is stored).

In FIG. 5, when it is determined in step (Xi) that the reading of the reduced rectangular coordinate data is completed, the vertical pixel coordinate is set to Y in step (Xii).
= 1 and, in step (Xiii), the data whose Y coordinate is y is read out of the data converted and recorded.

Next, in step (XiV), the read data is rearranged and recorded in the ascending order of the X coordinate (sort). In step (XV), it is determined whether or not the recording of the coordinate-converted data is completed. If not completed, in step (XVi), y = y + 1 is set, and the data is read in step (Xiii). And continue the subsequent operations.

In this way, the coordinate-converted data are input to the plate making computer 26 in the order in which they are recorded.

In the present invention, the elongation anisotropy of the metal material can be corrected during the coordinate conversion. At the portion which becomes the circumferential side wall portion of the draw-formed can, the extensional flow is generated in the height direction of the molded body and the contraction flow is generated in the circumferential direction. These plastic flows do not uniformly occur over the entire surface of the metal material 6, and the flow is anisotropic. FIG. 8 illustrates the anisotropy of the flow of the metal material 6, in which the elongation is the smallest in the rolling direction X and the direction Y perpendicular thereto when the metal material 6 is manufactured. It is recognized that the largest elongation is exhibited in the direction Z forming 45 degrees. Therefore, in the case of a material having a large degree of rolling, when the rectangular printing layer is simply converted into the annular printing layer and printing is performed on the metal material 6, the printing portion that is greatly stretched at every 45 degrees and the small stretching portion is stretched at every 45 degrees. There will be a printed part,
The printed image may have a waveform and the linearity in the circumferential direction may not be maintained. In addition, a positional deviation of the printed image in the circumferential direction also occurs due to the change in the elongation.

In the flowchart shown in FIG. 9 for explaining this correction,
Step (iV) and step (V) are the same as in FIG. In step (XVii) after step (iV), it is determined whether or not the above-described reduced rectangular coordinate value is in the anisotropy-considered setting position. If the reduced rectangular coordinate value is in the anisotropy-considered setting position, the screen shift data in the height direction and / or the circumferential direction at each position is read in step (XViii), the rectangular coordinate value is corrected, and then step (V )
Coordinate conversion in. If the position is other than the set position considering anisotropy, the coordinate conversion in step (V) is directly performed.

According to the present invention, by the operation described above, the pixel signal on the rectangular coordinates is reduced to the pixel signal in the height direction,
This is converted into a pixel signal or a group of pixel signals of the converted coordinates in correspondence with the converted coordinates when the reduced rectangular coordinates are expanded on the annular surface having substantially the same area as this rectangle, and the pixel signals on the converted coordinates are also converted. Can be read and output in the order of coordinates.

The pixel signals on the converted coordinates are output in the order of coordinates by the scanning mechanism.
It is supplied to 28 and a printing plate or a block copy is prepared.

Conversion from a pixel signal of reduced rectangular coordinates to a group of pixel signals or pixel signals of circular conversion coordinates is disclosed in JP-A-61-2670.
The method described in Japanese Patent No. 53 can also be used.

(Explanation of a preferred embodiment of the invention) As the input scanning mechanism 25, an arbitrary input mechanism known per se, for example, a document is read for one line in the X-axis direction (main scanning), and then the position is shifted in the Y-axis direction ( Sub-scan) 1
Cylindrical scanning or plane scanning type which sequentially reads line by line is used, and the reading operation is performed by detecting reflected light or transmitted light by a photomultiplier tube, a phototransistor, a charge coupling device, or the like. Generally, in a multicolor original, color separation is performed into cyan, magenta, yellow, and black, and input scanning is performed. Further, the number of scanning lines can be changed between the pattern original and the character original. Such a device is generally widely marketed under the name of a scanner and is easily available.

The plate-making computer 26 is a central processing unit (CPU) that receives and analyzes input / output commands, executes various programs, controls input / output devices, and the like, and a central processing unit (CPU).
A disk drive used to store the system and various files, and a magnetic tape used to read the system and save and restore various files. It is equipped with a device. A suitable example of such a plate making computer is commercially available as Response 300 series from Cytex of Israel.
The same thing can be used without being limited to this. For example, Studio 800 Series (Crossfield, UK), Chromacom System (Rudolf, West Germany)
Computers for plate making such as Hellsha, Pagematic System (Dainippon Ink and Chemicals), Sigma Maraf System 2000 (Dainippon Screen Mfg. Co., Ltd.) can also be used.

As the output scanning mechanism 28, any scanning recording method known per se, for example, a silver salt photography method, a dry silver recording method,
Electrophotography, electrostatic recording, negative or positive photoresist recording, photopolymer recording, diazo photography,
It is possible to employ various methods using a dichromated gelatin plate making method, an electrolytic recording method, an electric discharge breakdown recording method, an electric heat-sensitive recording method, a heat-sensitive recording method, a pressure-sensitive recording method, an inkjet recording method, etc., and also as a scanning method thereof. , Mechanical scanning such as cylindrical scanning, rotating disk scanning, helix cylindrical scanning, belt type planar scanning, and multi-needle electrode planar scanning; electron tube scanning such as fly spot tube type, optical fiber tube type, multi-needle electrode tube type; A solid-state scanning type such as a needle electrode head type is used.

In the present invention, among these various recording methods, the light energy can be concentrated in a minute region of the wavelength order, the light beam can be scanned over a wide range, and rapid on / off can be performed. It is desirable to use a laser recording method for reading and making a plate. As laser light source, He-Ne laser, Ar laser, He-
A Cd laser or the like is used.

In the present invention, the pixel density in the rectangular coordinate, the reduced rectangular coordinate and the final transformed coordinate can be changed in a wide range as desired, but generally speaking, it is used within the range of 12 to 100 dots / mm. Desirable among these are 12 to 14 dots / mm in the case of patterns and 36 in the case of characters.
It is desirable to set the range to 100 dots / mm.

Cyan, magenta, yellow and black-and-white plates can be directly manufactured by the output scanning mechanism 28 and used for printing materials, or negatives can be manufactured once and then reverse printed to manufacture printing plates. You can also

In the present invention, the reduced data in the rectangular coordinate, l / l _0, 1-
The value such as l / l ₀ may be stored in advance in the internal memory or the external memory of the deformation processing computer 30, or may be input for each image processing.

As the metal material of the can, untreated steel plate (black plate), various surface-treated steel plates, for example, tin-plated steel plate (tin plate), galvanized steel plate, aluminum-plated steel plate, nickel-plated steel plate, chrome-plated steel plate, and other plated steel plates; electrolysis Electrolytically treated steel plates such as chromic acid treated steel plates; chemically treated steel plates such as phosphoric acid and / or chromic acid treated steel plates, light metal plates such as aluminum, or composite materials thereof are used.

The surface plate thickness of the metal material varies depending on the final size of the container and the type of the material, but is preferably 0.1 to 0.5 mm, particularly preferably 0.10 to 0.35 mm.

For metal materials, a coating having excellent workability and corrosion resistance prior to printing, for example, an epoxy-phenolic coating,
Epoxy-aminoplast paint, epoxy-acrylic paint, epoxy-vinyl paint, etc. can be applied,
In addition, a whiting paint in which titanium oxide or the like is mixed with the above paint can be provided on the surface to be the printing surface.

Printing is lithographic printing using a plate manufactured by the method described above, offset printing, screen printing, gravure printing,
The printing can be carried out by any printing such as letterpress printing, intaglio printing, electrophotographic printing, etc. As the printing ink, any printing ink known per se or UV curable ink can be used.

In order to obtain a draw-formed can, the above-mentioned printed metal material is punched into a shape such as a disk, and is subjected to a one-step or multi-step pre-drawing process between the front drawing punch and the front drawing die, and then a small diameter re-formation is performed. Using a drawing punch and a redrawing die, a single-stage or multistage redrawing process is performed. At the time of this redrawing, a redrawing die having a small curvature is used as the redrawing die, and the side wall is thinned by bending and debending.

In general, the radius of curvature (R
If d) is set to 1 to 2.9 times, especially 1.5 to 2.9 times, the thickness of the pre-printed metal plate (t _B ), not only the thinning of the side wall can be effectively achieved by bending and stretching, but also the side wall. The variation in thickness between the lower part and the upper part of the is eliminated, and uniform thinning can be achieved throughout.

In FIG. 3D for explaining the bending and stretching process, the preprinted metal plate 17a is forcibly bent along the working corner portion 23 of the redrawing die having the curvature radius Rd under sufficient back tension. In this case, the material metal plate 17a
No strain is generated on the surface on the side of the working corner portion, whereas the surface on the side opposite to the side of the working corner portion is strained by tension. This strain amount ε _s is given by the following equation, where Rd is the radius of curvature of the working corner and t is the plate thickness. Given in. The surface (inner surface) of the metal plate is stretched by ε _s at the working corner portion, while the other surface (outer surface) is stretched by the back tension just below the working corner portion by the same amount as ε _s . As described above, the thickness of the coated metal plate is reduced by bending and stretching, and the thickness change rate ε _t is calculated by the following equation. Given in. From the above equation (10), it is effective to reduce the radius of curvature Rd of the working corner portion to reduce the thickness of the coated metal plate, that is, the smaller Rd is, the change in thickness | ε _t | You can see it grows. Further, if the radius of curvature Rd of the working corner portion is considered to be constant, it can be seen that the change in thickness | ε _t | increases as the thickness t of the coated metal plate passing through the working corner portion increases.

At the time of draw forming and redraw forming, various lubricants such as liquid paraffin, synthetic paraffin, edible oil, hydrogenated edible oil, palm oil, various natural waxes, and polyethylene wax are applied to the coated metal plate or further cups for forming. Is good. The coating amount of the lubricant varies depending on its type, but it is generally in the range of 0.1 to 10 mg / dm ² , particularly 0.2 to 5 mg / dm ² , and the lubricant is applied to the surface in a molten state. It is carried out by spray coating.

Drawing can be done at room temperature, but generally 20
It is desirable to carry out at a temperature of from 95 to 95 ° C, especially from 20 to 90 ° C.

The molded can is subjected to various processes such as flange trimming, doming, neck-in, and flange processing, to form a can body for two-piece canning.

(Effect of the Invention) According to the present invention, the digital pixel signal of the rectangular original is converted into the digital pixel signal of the rectangular coordinate compressed in the height direction in consideration of the degree of thinning of the side wall of the can, and the annular surface by the computer is converted. To form a printing plate by image processing as a pixel signal of the transformed coordinates by using the coordinate transformation to
By pre-printing the material for redraw forming, the H / D standard draw ratio is as high as 1.0 or more, and even though the side wall is significantly thinned, a printed image that is faithful to the original image can be obtained. It could be embodied on the side wall of a thinned deep-drawn can.

(Example) Example 1 A metal material is prepared in which tin-free steel having a plate thickness of 0.18 mm and a tempering degree of DR-9 is preliminarily coated with an inner paint on the inner surface of the can and a white coating on the outer surface of the can.

The rectangular print original shown in FIG. 2, h = 122.26 (m
m), l = 208.21 (mm) size, 4th
An input scanning mechanism shown in FIG. 25 inputs digital pixel signals to the plate making computer shown in FIG. A chromagraph 299 scanner system is used as an input scanning mechanism, and a response 320 system is used as a plate making computer. The input digital image has a size of h = 4401 (pixels) and l = 7496 (pixels).

The input image data is output to the deformation processing computer shown at 30 in FIG. A Facom M340S computer system is used as the transformation computer. The computer performs a reduction process in the height direction by the method shown in FIG. 6 in consideration of the fact that the side wall portion is stretched in the height direction and thinned by drawing and redrawing. Further, by the method shown in FIG. 7 and FIG. 9, coordinate conversion from rectangular coordinates to annular coordinates is performed in consideration of plastic flow and anisotropy in the height direction during draw forming. In FIGS. 7-A and 7-B for explaining this coordinate conversion, it is assumed that after reduction, l = 3521, m = 7496, and n = 6400.

The coordinate-converted data pixel signal is input to the plate making computer again, and an output scanning mechanism shown in FIG. 4 at 28 takes an annular shape in consideration of the plastic flow and anisotropy in the height direction shown in FIG. Create a printing plate with the developed image.
An ELP II laser plotter system is used as the output scanning mechanism.

The prepared printing plate is used to perform the offset printing method on the surface of the white coating of the metal material described above.

The printed metal material is punched into a circular blank with a diameter of 179 (mm) in the shearing step shown in FIG. 3-B.

Next, in the pre-drawing step shown in FIG. 3-C and the re-drawing step of bending and debending three times as shown in FIG. 3-D, a thinned draw forming can is manufactured. The manufacturing conditions of the redrawing process for thinning and forming are as follows.

・ Die radius of curvature (Rd) 2.0t _B・ Wrinkle pressing force (BHF) 5 (ton) ・ Final punch diameter 65.9 (mm) At this time, the weighing characteristics of the thin-walled draw-molded printing can are as follows. is there.

・ Can height / can diameter (H / D) 1.9 ・ side wall thickness / bottom thickness (t _W / t _B ) 0.8 ・ side wall printed image deviation (position 100 mm above the can bottom) axial deviation 2 % Or less Circumferential deviation amount 1% or less ・ Content amount 370 ml The thinned draw-formed printing can thus produced according to the present invention faithfully reproduces the original rectangular printing original, and the deviation amount is extremely small. A thinned draw-formed printing can was obtained.

Comparative Example On the metal material used in Example 1, a printing plate was prepared by image processing of the same size as a rectangular print original without considering that the side wall portion is stretched in the height direction by drawing and redrawing. Perform offset printing.

In addition, the manufacturing conditions for the drawing and redrawing process were also within the range generally used.

The point greatly different from production conditions of Example 1 to the curvature of the die radius (Rd) and 10t _B, otherwise were carried out under the same conditions.

As a result, the lightweight characteristics of this draw-formed printing can are
Only a product with a can diameter (H / D) of about 1.5, a side wall thickness / bottom thickness (t _W / t _B ) of 1.2 or more and an internal volume of about 300 ml was obtained.

Further, the deviation amount of the side wall printed image is larger than that of the first embodiment, and the deviation amount at the position 100 mm in height from the can bottom reaches 11 to 12% in the axial direction and 12 to 13% in the circumferential direction. In addition, the distortion of the printed image was recognized to the extent that it could be visually confirmed over the entire surface, and it was not possible to faithfully reproduce the rectangular printed document.

Example 2 A metal material having the following characteristics is prepared as the metal material shown in FIG.

-Al-Mg series aluminum alloy plate-Thickness 0.23 (mm) Using the above metal materials, except that the wrinkle holding force in the redraw forming step shown in Fig. 3-D is 1.5 (ton),
By the same method as in Example 1, a thin-walled draw forming printing can was manufactured.

As a result, the deviation of the printed image on the side wall of the draw-molded printing can is suppressed to 2% or less in the axial direction and 1% or less in the circumferential direction at a position 100 mm higher than the bottom of the can. It was possible to obtain a good thin-walled molded printing can made of aluminum that was reproduced and had a small amount of deviation.

[Brief description of drawings]

FIG. 1 is a perspective view showing a thin-walled draw-formed printing can body according to the present invention, FIG. 2 is a diagram showing a circumferential side wall portion of the thin-walled drawn-molded printing can body shown in FIG. -A, FIG. 3-B, FIG. 3-C, and FIG. 3-D are explanatory views for explaining the manufacturing process of the thinned draw forming printing can body shown in FIG. 1, and FIG. , A block diagram for explaining the image processing steps, FIG. 5 is a flowchart for explaining the operation of the digital image processing, and FIGS. 6-A and 6-B are the reduction of the rectangular original of the present invention. 7A and 7B are views for explaining the coordinate conversion from rectangular coordinates to an annular surface, and FIG. 8 is a difference in plastic flow in drawing and redrawing. Fig. 9 is a plan view of a plate having a printed image that takes into account the directionality, and Fig. 9 illustrates the coordinate conversion operation that takes into account the anisotropy of plastic flow. It is a flow chart of the order. Reference numeral 1 is a thinned draw forming printing can, 2 is a bottom portion, 3 is a peripheral side wall portion, 4 is a printing layer, 6 is a metal material, 7 is a printing plate,
8 is an annular printing layer, 9 is an inner peripheral portion, 10 is an outer peripheral portion, 11 is a shearing die, 12 is a shear punch, 13 is a circular blank, 14 is a front drawing die, 15 is a wrinkle retainer, 16 is a front drawing punch, 17 Is a front draw cup, 18 is an annular holding member, 19 is a redraw die, 20 is a redraw punch, 23 is a working corner portion, 24 is a rectangular original, 25 is an input operation mechanism, 26 is a plate making computer, 27 is for printing A plate, 28 is an output scanning mechanism, 29 is a recording material, and 30 is a deformation processing computer.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B65D 25/20 B65D 25/20 NG03F 1/00 G03F 1/00 P

Claims (2)

(57) [Claims] 1. A method for producing a draw-formed printing can having a printed image on a side wall of a can, which comprises subjecting a preprinted metal material to draw forming, wherein a reduction ratio in a height direction is reduced for a rectangular print original. Reduced digital in which the rows corresponding to the reduced portions of pixels are averaged so as to be approximately equal to the ratio of the average thickness of the side wall of the final can body (t _W ) / the bottom thickness of the final can body (t _B ). A printing plate is created by performing image processing, and at the same time as or subsequent to this, performing image processing for developing the reduction-processed document image on an annular surface having an area substantially the same as the area of the reduction-processed document image. After printing on the material using a printing plate and forming the printed metal plate into a front drawing cup, this front drawing cup is bent and rebent by using a redrawing die with a small curvature, and this Makes the side wall thinner A method for producing a thinned draw-formed printing can, which is characterized by: 2. A method of producing a draw-formed printing can having a printed image on a side wall of the can, which comprises subjecting a preprinted metal material to draw forming, wherein a reduction ratio in a height direction is reduced for a rectangular print original. Reduced digital in which the rows corresponding to the reduced portions of pixels are averaged so as to be approximately equal to the ratio of the average thickness of the side wall of the final can body (t _W ) / the bottom thickness of the final can body (t _B ). Image processing is performed, and at the same time or subsequently, the reduced original image is developed on an annular surface having an area substantially the same as the area of the reduced original image and corrected by the anisotropy of elongation of the metal material. After making a printing plate by image processing, print on the material using this printing plate, mold the printed metal plate into a front squeezing cup, and then replace the front squeezing cup with a small curvature. Bending and bending using a drawing die A method for producing a thin-walled draw-molded printing can, characterized in that the side wall portion is thinned by the deformation.