JP2021536378A - Manufacturing equipment for coated steel sheets using inkjet printing - Google Patents

Abstract

The present invention relates to an apparatus for manufacturing a coated steel plate using inkjet printing, which does not cause blurring of an image or clogging of the head nozzle due to light reflection even when produced for a long time, and this relates to inkjet printing on the surface of the steel plate. The printing device includes a printing device for printing using the ink head, and the printing device is arranged downstream of the ink head and an ink head that ejects ink cured by light to the printing area of the steel plate, and irradiates the ink in the printing area with light. The shielding member includes a light source and a shielding member arranged around the light source and preventing the light reflected from the steel plate from reaching the ink head, and the shielding member is obliquely directed toward the surface of the steel plate. It is characterized in that a plurality of concave grooves are formed in the surface.

Description

The present invention relates to an apparatus for manufacturing a coated steel sheet using inkjet printing, in which image blurring and head nozzle clogging due to light reflection do not occur even after long-term production.

Steel sheets with a pattern printed on the surface are divided into printed steel sheets using a silk screen and printed steel sheets using a roll printer. Silk-screen printed steel sheets are manufactured in an intermittent batch type process using a printing process on a sheet rather than a coil, and roll-printed steel sheets are ink on rolls with etched print patterns. The printed steel sheet with a pattern transfer paper is manufactured by using a method of transferring a transfer paper with a pattern engraved on the steel sheet to the steel sheet.

Such conventional techniques have the following problems.

The silk screen method has a relatively simple manufacturing process, but it is necessary to separately manufacture a screen that is a printing board depending on the type of pattern or product to be printed, and the number of screens increases depending on the number and type of hue. As a result, the work speed becomes slow and the productivity is low.

Unlike the silk screen method, the roll printing method has high productivity because it is a continuous coil coating method, but it is difficult to diversify the product design because the printed pattern is simple and it is difficult to realize various patterns. Further, as in the silk screen method, the number of print rolls increases depending on the number of hues, and there is a drawback that the production process is complicated and the production efficiency is low.

As a reference, as the prior art related to the present invention, Korean Patent Publication No. 2018-0021321 can be mentioned.

Therefore, an object of the present invention is to provide a coating steel sheet manufacturing apparatus capable of improving productivity and print quality by using inkjet printing.

Another object of the present invention is to provide an apparatus for manufacturing a coated steel sheet using inkjet printing, which does not cause image blurring or head nozzle clogging due to light reflection even after long-term production.

The apparatus for manufacturing a coated steel plate according to an embodiment of the present invention includes a printing apparatus that prints on the surface of the steel plate by using inkjet printing, and the printing apparatus includes an ink head that ejects ink cured by light to a printing area of the steel plate. A light source that is arranged downstream of the ink head and irradiates the ink in the printing area with light, and a light source that is arranged around the light source to prevent the light reflected from the steel plate from reaching the ink head. The shielding member includes a shielding member, and the shielding member is characterized in that a plurality of concave grooves are formed in an oblique direction on a surface facing the steel plate.

According to the present invention as described above, continuous coil process production is possible by using inkjet printing, the process is simple, but the production speed and efficiency are high, and various patterns and hues are realized with high resolution. Therefore, the effect of printing on a steel plate can be obtained without causing distortion in the computer digital image.

Further, according to the present invention, even if the printing height is increased in order to prevent the head from being damaged due to the flatness of the steel plate, the printing speed is dramatically increased without degrading the image quality. It is possible to print a vivid image for a long time by extending the service life because the nozzle of the head is not clogged.

It is a figure which showed schematicly the manufacturing apparatus of the coated steel sheet by one Embodiment of this invention. It is a perspective view which showed the main part of the printing apparatus among the manufacturing apparatus of the coated steel sheet by one Embodiment of this invention. It is sectional drawing of FIG. It is a bottom view of FIG. It is a schematic diagram for demonstrating the state which the image blurring and the nozzle clogging of a head occur. It is a graph which showed the change of the intensity of light by the number of reflections. It is a bottom view which showed the other modification of the shielding member. It is a bottom view which showed the further modification example of the shielding member. It is a photograph for comparing the image quality of this invention and the prior art. It is an enlarged photograph of a part of FIG.

Hereinafter, description will be made in detail with reference to the exemplary drawings of the present invention. However, it should be noted that when assigning drawing codes to the components of each drawing, the same components are given the same code as much as possible even if they are displayed on different drawings. .. Further, in explaining the present invention, if it is determined that a specific description of the related known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted. do.

FIG. 1 is a diagram schematically showing an apparatus for manufacturing a coated steel sheet according to the first embodiment of the present invention.

Although not shown in the drawings, the steel sheet can go through a step of forming a coating layer before entering the printing step. That is, the coated steel sheet manufacturing apparatus can include a process of forming a coating film layer and a process of forming a printing layer on the coating film layer by using inkjet printing. Here, the coated steel sheet means a steel sheet in which a coating film layer or a printed layer is formed on the surface.

The coating steel sheet manufacturing equipment includes a tension control device 10 that applies tension so that the steel sheet is maintained in a flat state without bending, and the steel sheet moves unevenly to the left and right without moving along the center of the production line. The meandering control device 20 that prevents this from happening, the speed control devices 30 and 40 that maintain the traveling speed of the steel sheet so that the ink drops exactly at the desired position when the ink is dropped on the steel sheet, and the design that drops the ink on the steel sheet. Alternatively, it may include a printing device 100 for printing hues.

Referring to the drawings, the tension control device 10, the meandering control device 20, the deflector roll 51 (Defector Roll), the dancer roll 53 (Dancer Roll), the speed control device 30, the printing device 100, the deflector roll 52, from the approach direction of the steel plate. And the speed control device 40 can be continuously provided.

The tension control device 10 can keep the steel plate within the set tension range by adjusting the speed and the contact angle of the tension bridle rolls 11 and 12 (Tension Bridle Roll). The tension range can be set to a range in which the surface shape of the steel sheet is flattened and fracture does not occur due to excessive tension. As an example, the tension range can be set within the ^{range of 2-4 kgf / mm 2.} At this time, the tension error of the steel sheet is adjusted to be within the range of -1 to + 1%, and the tension of the steel sheet can be maintained.

Two tension bridle rolls 11 and 12 can be placed adjacent to each other. The steel plate enters along the upper surface of the tension bridle roll 11 located in the approach direction, and advances along the lower surface of the tension bridle roll 12 located in the advance direction. Here, the magnitude of the tension applied to the steel sheet can be adjusted by changing the vertical position (or horizontal position) of any one of the tension bridle rolls.

A tension measuring sensor 13 for measuring the tension of the steel plate can be installed downstream of the tension bridle rolls 11 and 12. This tension measuring sensor measures the tension of the steel sheet and transmits a signal to the tension control system 14. When the tension of the steel sheet above the set range is measured, this tension control system transmits an operation signal to the tension bridle roll so as to reduce the tension of the steel sheet, and when the tension of the steel sheet below the set range is measured. In, an operation signal is transmitted to the tension bridle roll so as to increase the tension of the steel sheet.

The meandering control device 20 is a shaft of the steering rolls 21 and 22 (Steering Roll) according to the meandering amount indicating the degree to which the center position in the width direction of the steel plate is deviated from the center of the steel plate transport line, which is notified by the meandering measurement sensor 23. Can be rotated and moved. As an example, the meandering amount of the steel sheet can be controlled to be within the range of -1 to + 1 mm.

The steering rolls 21 and 22 can be located downstream of the tension bridle rolls 11 and 12.

Further, the two steering rolls 21 and 22 can be arranged adjacent to each other. The steel plate can be transported along the upper surface of two adjacent rolls. Here, the meandering of the steel plate can be controlled by changing the position in the width direction of the steel plate of any one of the steering rolls (or the gradient in the width direction of the steel plate of the rotating shaft).

A meandering measurement sensor 23 for measuring meandering of a steel plate can be installed downstream of the steering rolls 21 and 22. This meandering measurement sensor measures the meandering of the steel plate and transmits a signal to the meandering control system 24. This meandering control system transmits an operation signal to the steering roll to move the steel plate to the left when the steel plate meanders to the right, and moves the steel plate to the right when the steel plate meanders to the left. The operation signal is transmitted to the steering roll so as to move to.

Further, the meandering measurement sensor 23 may be connected to the printing device 100. As an example, when the degree of meandering of the steel sheet exceeds the dangerous range, the operation of the printing apparatus 100 can be stopped.

The speed control devices 30 and 40 can maintain the speed in the traveling direction of the steel sheet at the set speed by adjusting the rotation speed of the pinch rolls 31 and 41 (Pinch Roll). This is because the ink drops in a desired position when the speed of the steel sheet is kept constant. For example, the set speed of the steel sheet can be selected from the range of 30 mpm to 50 mmp. At this time, the fluctuation amount of the actual traveling speed of the steel sheet can be controlled to be within the range of -21 to +21 μm / sec.

The pinch rolls 31 and 41 can consist of two rolls arranged above and below the steel plate. Here, the traveling speed of the steel sheet can be adjusted by changing the rotation speed of any one or more pinch rolls.

Further, the pinch rolls 31 and 41 can fix the movement of the steel sheet in the width direction and reduce the vibration in the width direction. As an example, the pinch roll is adjusted so that the horizontal vibration width of the steel sheet is maintained within the range of -11 to +11 μm.

Further, the pinch rolls 31 and 41 can be installed on at least one of the upstream side and the downstream side of the printing apparatus 100. The drawing shows an example in which pinch rolls are installed both upstream and downstream of the printing device. For example, the pinch roll is installed only downstream of the printing device to control the speed while pulling the steel plate. Alternatively, the speed may be controlled while being installed only upstream of the printing apparatus and extruding the steel plate.

The deflector rolls 51 and 52 can be used to change the traveling direction and angle of the steel sheet. As an example, it is provided between the meandering control device 20 and the speed control devices 30 and 40 to change the traveling direction of the steel sheet, and is provided between the printing device 100 and the speed control devices 30 and 40 to change the traveling direction of the steel sheet. Can be changed.

The dancer roll 53 can move within a small range in the vertical direction of the steel plate by installing a vibration reducing member between the dancer roll 53 and the base. Therefore, the dancer roll can reduce the vibration of the steel sheet and can also adjust the tension of the steel sheet.

Specifically, the dancer roll 53 can reduce the vibration of the steel plate generated in the process of passing through the tension control device 10 and the meandering control device 20. As an example, the dancer roll is adjusted so that the vertical vibration width of the steel sheet is maintained within -60 to +60 μm.

On the other hand, the printing apparatus 100 includes a close contact transfer unit 120 that allows the steel sheet to extend flat without bending in a jetting zone or a printing area where ink drops, and a steel plate support that adjusts the vertical position of the steel sheet. A position adjusting unit (not shown) of rolls 131 and 132 can be included.

The close contact transfer unit 120 can bring the steel sheet into close contact with the conveyor belt 133 by vacuum to flatten the surface of the steel sheet. As described above, the flatness of the surface of the steel sheet is achieved by the tension control device 10, but residual waves remain finely on the surface of the steel sheet. For example, when the distance between the ink head 101 and the steel plate is 0.5 to 1.0 mm, if the steel plate moving at a speed of 30 to 50 mmp collides with the ink head, the printing apparatus 100 may be damaged. .. Therefore, the residual wave is removed by using another close contact transport unit.

The position adjustment unit of the steel plate support rolls 131 and 132 adjusts the vertical position of the steel plate support roll that supports the steel plate and controls the vertical position of the designated steel plate, so that the ink drops to the correct position of the steel plate. Can be done. As an example, the position adjusting unit of the steel plate support roll can adjust the vertical position of the steel plate support roll so that the vertical vibration width of the steel plate is maintained within -60 to +60 μm.

The tension control device 10, the meandering control device 20, the speed control devices 30, 40, the close contact transfer unit 120 of the printing device 100, the position adjustment unit of the steel plate support rolls 131, 132, and the like described above have high resolution on the steel plate by inkjet printing. It plays a role in creating steel plate conditions in the ink head, which enables the formation of digital images with high accuracy. That is, in the jet area or the printing area where the ink drops to form an image, the center position of the steel sheet in the width direction of the steel sheet must be located at the center of the steel sheet transport line, and the distance from the ink head is the set value. Need to be maintained.

The printing apparatus 100 can perform inkjet printing on the surface of the steel sheet by injecting ink onto the steel sheet moving in the printing area.

FIG. 2 is a perspective view showing a main part of a printing apparatus among the apparatus for manufacturing a coated steel sheet according to an embodiment of the present invention, FIG. 3 is a cross-sectional view of FIG. 2, and FIG. 4 is a bottom view of FIG. Is.

As shown in these drawings, the coated steel plate manufacturing apparatus according to one embodiment of the present invention includes a printing apparatus 100 that prints on the surface of the steel plate by using ink jet printing, and the printing apparatus is cured by light. An ink head 101 that ejects ink to the print area of the steel plate 1, a light source 103 that is arranged downstream of the ink head and irradiates the ink in the print area, and a light source 103 that is arranged around the light source and reflected from the steel plate. A shielding member 150 for preventing light from reaching the ink head is included, and the shielding member has a plurality of concave grooves 151 formed in an oblique direction on a surface facing a steel plate.

The ink head 101 is provided with a plurality of nozzles 102 arranged so as to face downward, and the plurality of nozzles can be arranged so as to be arranged at uniform intervals in the width direction of the steel plate 1. Uniform print quality can be obtained when the nozzles are arranged at regular intervals.

Further, a plurality of ink heads 101 can be arranged side by side in the traveling direction of the steel plate. Each ink head arranged in the traveling direction of the steel plate 1 can inject ink having different hues from each other. For example, ink heads for injecting inks of C (Cyan), M (Magnenta), Y (Yellow), and K (Black) hues can be arranged side by side along the traveling direction of the steel sheet.

At least one ink head 101 for injecting ink having a single hue can be arranged in the width direction of the steel plate 1. If the length of the ink heads is sufficient to cover the width of the steel plate, one ink head may be arranged, but if the length of the ink heads is smaller than the width of the steel plate, a plurality of ink heads may be arranged. Ink heads can be used by connecting them in the width direction of the steel plate.

The ink heads 101 arranged along the traveling direction of the steel plate 1 can be arranged so that a part of the heads overlap each other in the traveling direction of the steel plate. At this time, in each ink head, the nozzles 102 located on the outermost side in the width direction of the steel plate can be arranged so as not to overlap with each other in the traveling direction of the steel plate. As a result, it is possible to print uniformly over the entire area of the steel sheet in the width direction of the printed area without causing blurring.

Further, the printing apparatus 100 can include an ink supply apparatus (not shown) capable of continuously supplying ink without bubbles. This ink supply device can be connected to the ink head 101 to supply ink to the nozzle 102, can be detachably coupled to the ink head, and can be provided so as to be replaceable when the ink is insufficient.

As the ink, an ink that is cured by light can be used.

Ultraviolet (UV) light is used as the light emitted from the light source 103, and the ink can be cured.

The ink droplets (Droplets) 2 ejected onto the steel plate 1 continuously spread over time, but the larger the size of the ink droplets, the lower the resolution of the printing image. Therefore, the light source 103 can cure the ink so that the ink does not spread more than an appropriate spreading amount.

The light source 103 can be arranged downstream of the ink head 101. For example, a light source can be arranged downstream of the ink head in charge of one hue. In this case, the C hue ink head, the light source, the M hue ink head, the light source, the Y hue ink head, the light source, the K hue ink head, and the light source can be arranged in this order in the traveling direction of the steel plate.

The distance between the ink heads 101, the distance between the light sources 103, and the distance between the adjacent ink heads and the light source can be constant. As a result, the degree to which each hue is cured can be made uniform.

The printing apparatus 100 can further include a base frame 105 for fixing the ink head 101 and the light source 103.

The base frame 105 can combine a plurality of ink heads 101 and a plurality of light sources 103 as one unit. As an example, the base frame extends in the traveling direction of the steel plate 1 and can combine a plurality of ink heads and a plurality of light sources.

One base frame 105 can combine the ink head 101 and the light source 103 as one unit, but unlike this, a plurality of base frames may be provided for each hue.

The base frame 105 can include an opening 106 for accommodating the ink head 101 and an opening 104 for the light source 103.

The distance between the steel plate 1 and the nozzle 102 of the ink head 101 is adjustable. The closer the distance between the steel sheet and the nozzle is, the better the print quality is. However, due to constraints such as the strength and intrinsic flatness of the steel sheet used as the printing material, the distance between the steel sheet and the nozzle is practically The distance of is not as close as possible.

For example, if the distance between the steel plate 1 and the nozzle 102 of the ink head 101 is smaller than about 0.5 mm, the steel plate may collide with the ink head and the printing apparatus 100 may be damaged. Since the steel sheet is not a perfect flat surface and contains fine waves, a safe distance is required between the steel sheet and the nozzle.

FIG. 5 is a schematic diagram for explaining a state in which image blurring and head nozzle clogging occur.

For example, as shown in FIG. 5, when inkjet printing is performed with the distance between the steel plate 1 and the nozzle 102 of the ink head 101 being about 3 mm, the light emitted from the light source 103 is reflected from the surface of the steel plate. It is scattered and the reflected light thus scattered reaches the nozzle of the ink head.

Here, the average reflectance on the surface of the steel sheet is about 87%, and some products have a mirror-like surface and the reflectance reaches 95%.

The intensity of the light reflected from the surface of the steel plate 1 is weakened, but it reaches the vicinity of the ink head 101 and pre-cures the falling ink droplets 2, which causes the ink to spread poorly. Become. As a result, the ink that has fallen on the steel sheet is not sufficiently spread and is cured, and a blurred image is printed.

Further, a part of the reflected light reflected and scattered from the surface of the steel plate 1 is applied to the nozzle 102 of the ink head 101, and the ink adhered to the nozzle is cured after the ejection is completed. After that, the cured ink causes nozzle clogging, which makes it impossible to eject the ink smoothly, which adversely affects the print quality. For example, ink may not be ejected from a portion where the nozzle is clogged, and there is a risk of streaks appearing in the printed image.

Therefore, a safe distance is secured between the steel plate 1 and the nozzle 102 of the ink head 101, and even if the distance between the steel plate and the nozzle is about 3 mm or more, the image is blurred or the head nozzle is clogged during printing. The coating steel sheet manufacturing apparatus according to the embodiment of the present invention is characterized in that the printing apparatus 100 includes a shielding member 150 that prevents the light reflected from the steel sheet from reaching the ink head. And.

In the shielding member 150, a plurality of concave grooves 151 are formed on the surface toward the steel plate 1 in an oblique direction with respect to the traveling direction of the steel plate. In addition, the shielding member may be made of a material capable of absorbing reflected light or coated with a coating material having a hue similar to black or black, and as a specific example, anodizing a metal material such as aluminum. Anodizing coating may be applied.

The shielding member 150 can be integrally formed with the base frame 105, or can be manufactured separately and then coupled or assembled to the base frame using any fixative (eg, fixing screw).

The groove wall of the concave groove 151 formed in the shielding member 150 is preferably at an angle of about 90 degrees, that is, at a right angle to the surface of the steel plate 1, but is not necessarily limited to this, and is, for example, a light source. It can have an arbitrary angle according to the change in the irradiation angle from 103 and the reflection angle due to the change in illuminance on the surface of the material.

In this way, by maximizing the number of times the reflected light is reflected in the shielding member 150 and causing it to be reflected inside the concave groove 151, the intensity of the light passing through the shielding member can be reduced.

On the other hand, due to the structure of the concave groove 151 of the shielding member 150 extending in the diagonal direction, the reflected light may be repeatedly internally reflected toward the upstream side, in other words, toward the ink head 101, and may pass through the concave groove. be. In order to prevent this, a blocking wall 152 that crosses the concave groove can be further formed at the end portion of each concave groove that is open to the ink head on the upstream side. As a result, each concave groove of the shielding member can confine the reflected light inside the groove, and the number of internal reflections can be increased.

FIG. 6 is a graph showing the change in light intensity depending on the number of reflections.

As shown in this, the shielding member 150 made of aluminum without a coating (Bare state) has a low intensity of reflected light of about 8% when the number of internal reflections reaches 30 times. Become. Therefore, it is preferable to design the concave groove 151 to a depth at which internal reflection occurs at least 30 times or more in the concave groove of the shielding member.

Further, the number of the concave grooves 151 has a strength that does not induce the curing of the ink even if the reflected light continuously contacts the nozzle 102 of the ink head 101 during the printing time of the steel sheet (about 100 minutes, 50 mpm standard). Can be set to.

For example, in consideration of the safety factor, the intensity of the reflected light that does not cause clogging of the nozzle of the head even after being irradiated for up to 300 minutes is 0.00006% of the initial intensity, and the number of internal reflections at this time is 88 times. The depth and number of the concave grooves 151, which are design variables of the shielding member 150, can be changed according to the printing height and the minimum reflection angle of the steel plate surface in consideration of the number of internal reflections in the concave grooves.

FIG. 7 is a bottom view showing another modified example of the shielding member.

In the shielding member 150 shown in FIG. 7, a plurality of concave grooves 151 are formed on the surface toward the steel plate 1 in an oblique direction with respect to the traveling direction of the steel plate, and the plurality of concave grooves are bent in the middle. Have. As a result, a plurality of concave grooves formed in a substantially V shape can be arranged on both sides of the light source 103.

As described above, when the plurality of concave grooves 151 are formed in a shape bent in the middle, there is an advantage that the blocking wall 152 in the concave grooves can be arranged only on the tip side on one side of the shielding member 150.

First, the concave groove 151 bent in the middle maximizes the number of times the reflected light is reflected so that the reflected light is reflected inside the concave groove, so that the intensity of the light passing through the shielding member 150 can be reduced. ..

Further, these concave grooves 151 are repeatedly internally reflected by the bent diagonally extending structure so that the reflected light is mainly reflected downstream, in other words, toward the light source 103 or downstream thereof. At this time, even if the reflected light passes through the concave groove, it is emitted toward the light source or its downstream, so that the possibility that the reflected light reaches the ink head 101 can be significantly reduced.

Here, on the upstream side in the concave groove 151, the advance of the reflected light is blocked by the blocking wall 152.

FIG. 8 is a bottom view showing still another modification of the shielding member.

In the shielding member 150 shown in FIG. 8, a plurality of concave grooves 151 are formed on the surface toward the steel plate 1 in an oblique direction with respect to the traveling direction of the steel plate, and a plurality of concave grooves 151 are formed in each of the concave grooves. The partition wall 153 is formed. As a result, a plurality of concave grooves formed in a grid pattern in a substantially diagonal direction can be arranged.

As described above, when the plurality of concave grooves 151 are formed in a grid pattern in the diagonal direction, it is not necessary to separately form a blocking wall in the concave grooves.

Further, the groove wall or the partition wall 153 of each concave groove 151 is provided with a protruding surface 154 protruding from the wall surface, and at least two spatial layers can be formed in each concave groove. FIG. 8 shows an example in which three spatial layers are formed as an enlarged cross-sectional view.

The concave groove 151 having the plurality of spatial layers can be formed by molding or machining at the time of manufacturing the shielding member 150. Alternatively, a concave groove having a plurality of spatial layers may be formed by laminating a plurality of thin plate members having holes or grooves corresponding to the concave grooves.

In this way, in the concave groove 151 having a plurality of spatial layers inside, the number of times the reflected light is reflected is maximized so that the reflected light is reflected inside the concave groove, thereby increasing the intensity of the light passing through the shielding member. Can be lowered.

Further, these concave grooves 151 can confine the reflected light inside the concave groove 151 due to the internal structure in which the plurality of spatial layers and the protruding surface 154 are formed, and the number of internal reflections can be increased. This can significantly reduce the possibility that the reflected light cannot escape from the concave groove and reach the ink head 101.

In the apparatus for manufacturing a coated steel plate according to an embodiment of the present invention, in order to confirm the influence of the shielding member 150 of the printing apparatus 100 on the image quality, the present invention is carried out in which the shielding member is attached while changing the printing height. The test was performed with an example and a comparative example of the prior art without a shielding member.

As the printing conditions, printing was performed at a steel plate speed of 50 mpm, an ink ejection speed of 20 kHz, and a resolution of 600 dpi, and the printing height, that is, the distance between the steel plate and the nozzle 102 of the ink head 101 was 0.5 mm and 1 mm. It was divided into 2 mm and 3 mm.

When printing on a steel plate by the conventional technique, the nozzle clogging of the head did not occur when the recommended printing height, that is, the distance between the steel plate 1 and the nozzle 102 of the ink head 101 was within 1 mm, but 1 mm was used. If it exceeds the limit, nozzle clogging occurs and the image quality is deteriorated.

On the other hand, when printing is performed by attaching the shielding member 150 to the printing device 100 as in the device for manufacturing the coated steel sheet according to the embodiment of the present invention, the nozzle of the head is printed even at a printing height of 3 mm. No clogging occurred.

Therefore, according to the present invention, even when the printing height, that is, the distance between the steel sheet 1 and the nozzle 102 of the ink head 101 must be unavoidably increased due to the constraint conditions such as the flatness of the steel sheet itself. Since the head nozzle was not clogged during printing, it was confirmed that damage to the head due to poor flatness of the steel plate was prevented and that a vivid image could be printed for a long time.

FIG. 9 is a photograph for comparing the image quality of the present invention and the prior art, and FIG. 10 is an enlarged photograph of a part of FIG.

9 and 10 are images of a coated steel plate using the inkjet printing of the present invention and the prior art when the printing height, that is, the distance between the steel plate 1 and the nozzle 102 of the ink head 101 is 3 mm. Shows quality.

In the embodiment of the present invention to which the shielding member 150 is attached, a vivid and dark image is realized even when the printing height is 3 mm, whereas in the comparative example of the prior art without the shielding member, the printing height is high. It can be seen that a blurred image is printed at 3 mm. In particular, a comparative example of the prior art shows an example in which a blurred image is printed as a result of the reflected light pre-curing the falling ink droplets and deteriorating the spread of the ink.

As described above, according to the present invention, by using inkjet printing, digital images can be continuously printed on a steel plate, continuous coil process production is possible, and printing is performed to prevent head damage due to the flatness of the steel plate. Even if the height is increased for printing, the printing speed can be dramatically increased without degrading the image quality, and the head nozzle is not clogged, so that the service life can be extended. It has the effect of being able to print vivid images for a long time.

The above description is merely an exemplary explanation of the technical idea of the present invention, and a person having ordinary knowledge in the technical field to which the present invention belongs does not deviate from the essential characteristics of the present invention. Various modifications and modifications are possible. Therefore, the embodiments disclosed in the present specification and the drawings are not for limiting the technical idea of the present invention, but for explaining the present invention, and such an embodiment covers the scope of the technical idea of the present invention. Not limited. The scope of protection of the present invention should be construed as being included in the scope of the claims of the present invention, and all technical ideas within the equivalent scope should be construed as being included in the scope of rights of the present invention.

The present invention is useful for manufacturing coated steel sheets using inkjet printing.

Claims (8)

Includes a printing device that prints on the surface of a steel sheet using inkjet printing.
The printing device is
An ink head that ejects light-cured ink to the printed area of a steel sheet,
A light source arranged downstream of the ink head and irradiating the ink in the printing area with light,
A shielding member arranged around the light source and preventing the light reflected from the steel plate from reaching the ink head, and the like.
The shielding member is a coated steel sheet manufacturing apparatus in which a plurality of concave grooves are formed in an oblique direction on a surface facing the steel sheet. The printing apparatus further includes a base frame for fixing the ink head and the light source.
The coated steel sheet manufacturing apparatus according to claim 1, wherein the base frame includes an opening for the ink head and an opening for the light source. The coated steel sheet manufacturing apparatus according to claim 1, wherein a blocking wall that crosses the concave groove is formed in each concave groove at an end opened to the upstream side. The coated steel sheet manufacturing apparatus according to claim 1, wherein the plurality of concave grooves have a shape bent in the middle. The coated steel sheet manufacturing apparatus according to claim 1, wherein a plurality of partition walls crossing the concave groove are formed in each concave groove. The coated steel sheet according to claim 5, wherein the groove wall or partition wall of each concave groove is provided with a protruding surface protruding from the wall surface, and at least two spatial layers are formed in each of the concave grooves. manufacturing device. The coated steel sheet manufacturing apparatus according to any one of claims 1 to 6, wherein the shielding member is made of a material capable of absorbing light or coated with a black coating material. The depth and number of the concave grooves can be changed in consideration of the number of internal reflections of the reflected light in the concave grooves.
The coating according to any one of claims 1 to 6, wherein the number of internal reflections is the number of times when the intensity of the reflected light is 0.8% or less of the intensity of the initial light. Steel plate manufacturing equipment.

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