KR20180135640A - Apparatus of coating steel sheet using inkjet printing - Google Patents

Abstract

Disclosed is a manufacturing apparatus of a coating steel sheet using inkjet printing. The manufacturing apparatus of a coating steel sheet according to an embodiment of the present invention comprises a printing device for printing on the surface of the steel sheet using the inkjet printing. The printing device includes: a dummy ink head arranged on a printing region in the proceeding direction of the steel sheet; a plurality of ink heads disposed behind the dummy ink head; and a plurality of dimples formed on the lower surface of the dummy ink head facing the steel sheet.

Description

[0001] APPARATUS OF COATING STEEL SHEET USING INKJET PRINTING [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for manufacturing a coated steel sheet, and more particularly to an apparatus for producing a coated steel sheet using inkjet printing.

A steel sheet having a pattern printed on its surface can be divided into a printed steel sheet using a silk screen, a printed steel sheet using a roll printer, and a printed steel sheet using a pattern transfer sheet. Silk-screen printed steel sheet is a batch type process that uses a printing process on a sheet rather than a coil, and a roll-printed steel sheet is coated with an ink or paint on a roll having an etched print pattern. And a pattern transfer paper printing steel sheet is transferred onto a steel sheet by transferring a pattern engraved with a pattern.

However, such conventional techniques have a problem.

In the case of the silk screen method, the manufacturing process is relatively simple. However, it is necessary to separately prepare the screen of the printing plate according to the pattern to be printed or the type of the product, and the number of the screen increases depending on the number of the colors, Slowly, productivity is weak.

Unlike the silk-screen printing method, the roll printing method is a continuous coil coating method, so productivity is high. However, it is difficult to implement various designs because of simple printing patterns and difficult to implement various patterns. In addition, as in the case of the silk screen method, the number of printing rolls is increased according to the number of colors, and production efficiency is lowered due to the complexity of the production process.

Japanese Laid-Open Patent Application No. 2013-111844 (published on June 10, 2013)

An embodiment of the present invention is to provide an apparatus for manufacturing a coated steel sheet capable of improving a productivity and a printing quality by allowing a uniform flow field to develop in a printing region when a printing pattern is coated on a steel sheet by using inkjet printing.

According to an aspect of the present invention, there is provided a printing apparatus for printing on a steel sheet surface using inkjet printing, the printing apparatus comprising: a dummy ink head disposed on a printing region in a traveling direction of the steel sheet; And a plurality of dimples are formed on the lower surface of the dummy ink head facing the steel plate.

And a dummy curing device disposed between the dummy ink head and an ink head disposed behind the dummy ink head, wherein the plurality of dimples can be formed on a lower surface of the dummy curing device.

According to another aspect of the present invention, there is provided a printing apparatus for printing on a steel sheet surface using ink-jet printing, wherein the printing apparatus includes a plurality of ink heads and a plurality of curing apparatuses And a plurality of dimples are formed on the lower surface of the base frame. The apparatus for manufacturing a coated steel sheet according to claim 1,

Further, the depth of the dimple is 10 to 50% of the printing height formed between the ink head and the steel plate.

And the diameter of the dimple is 1 to 5 times the depth of the dimple.

The distance between the dimples is 0.5 to 5 times the depth of the dimple.

And the number of the dimples is 20 to 50.

And further comprises a close transfer unit for supporting the steel sheet below the printing area of the printing apparatus.

The apparatus further includes a tension control device for applying tension to the steel plate, a yaw control device for preventing the steel strip from skewing, and a speed control device for maintaining the progress speed of the steel strip.

The apparatus for manufacturing a coated steel sheet using inkjet printing according to an embodiment of the present invention reduces the occurrence of uneven flow that may affect the ink head due to external flow by forming dimples on the lower surface of the base frame or the dummy ink head It is possible to prevent ink bleeding.

1 is a view schematically showing an apparatus for manufacturing a coated steel sheet according to an embodiment of the present invention.
2 is a side enlarged view showing a difference in dropping point of ink according to the influence of ambient air flow.
3 is a side view showing a printing unit according to the first embodiment of the present invention.
4 is a bottom view of the printing unit according to the first embodiment of the present invention.
5 is a side enlarged view showing a printing unit according to a second embodiment of the present invention.
6 is a bottom view showing a printing unit according to a second embodiment of the present invention.
7 is a flow analysis range for analyzing the change of the flow field in the printing region by the external flow field according to the embodiment of the present invention.
8 shows the flow field in the printing area in the absence of an external flow field.
9 shows the flow field in the printing area when an external flow is generated outside the dummy ink head.
FIG. 10 illustrates a flow field in a printing region when an external flow is generated in the presence of a dimple according to an embodiment of the present invention.
Fig. 11 is a structural diagram for explaining a close contact transfer unit according to the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments described below are provided by way of example so that those skilled in the art will be able to fully understand the spirit of the present invention. The present invention is not limited to the embodiments described below, but may be embodied in other forms. In order to clearly explain the present invention, parts not related to the description are omitted from the drawings, and the width, length, thickness, etc. of the components may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

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

Although not shown in the drawing, the steel sheet may undergo a step of forming a coating layer before entering the printing process. That is, the apparatus for manufacturing a coated steel sheet may include a process of forming a coat layer and a process of forming a print layer using inkjet printing on the coat layer. Here, the coated steel sheet refers to a steel sheet having a coating layer or a printed layer formed on its surface.

The apparatus for manufacturing a coated steel sheet includes a tension control device (10) for imparting a tension to a steel sheet so as to keep the steel sheet in a flat state without bending the steel sheet, a meander control device (10) for preventing the steel sheet from shifting to the left and right without moving along the center of the production line A speed control device (30, 40) for maintaining the speed of the steel plate so that the speed of the steel plate is accurately dropped to the position required by the ink when the printing ink is dropped on the steel plate, The printing apparatus 100 may include a plurality of printing apparatuses.

A deflector roll 51, a dancer roll 53, a speed control device 30, a tension control device 10, a skew control device 20, a deflector roll 51, The printing apparatus 100, the deflector roll 52, and the speed control device 40 may be continuously provided.

The tension controller 10 can maintain the steel sheet within the set tension range by adjusting the speed and contact angle of the tension bridle rolls 11 and 12 (TBR). The tension range can be set within a range in which the surface profile of the steel sheet is flattened, but the rupture does not occur due to excessive tension. For example, the tension range may be set within the range of 2 kgf / mm 2 to 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%, so that the tension of the steel sheet can be maintained.

The tension bridle rolls 11 and 12 may include two rolls arranged adjacent to each other. The steel sheet enters along the upper surface of the tension breeze roll 11 located in the entering direction (hereinafter referred to as the front), and the lower portion of the tension breeze roll 12 located in the advancing direction Advance along the surface. At this time, it is possible to adjust the magnitude of the tension applied to the steel plate by changing the vertical position (or horizontal position) of one of the tension brie rolls 11, 12. [

A tension measuring sensor 13 for measuring the tension of the steel plate may be provided at the rear of the tension bridle rolls 11, The tension measuring sensor 13 measures the tension of the steel plate and transmits a signal to the tension control system 14. The tensile force control system 14 transmits an operation signal to the tensile briide rolls 11 and 12 so as to lower the tensile force of the steel plate when the tensile force of the steel plate is measured in a set range or more, The operation signal is transmitted to the tension brie rolls 11 and 12 so as to increase the tension of the steel sheet.

The steer angle control device 20 controls the steer angle of the steering rolls 21 and 22 (SR) according to the amount of deviation, which is the degree of deviation from the center of the steel plate conveyance line, The axis can be rotated and moved. For example, the amount of meandering of the steel sheet can be controlled within the range of -1 mm to +1 mm.

The steering rolls 21, 22 may be located behind the tension brie rolls 11, 12.

Further, the steering rolls 21 and 22 may include two rolls arranged adjacent to each other. And the steel sheet can be conveyed along the upper surface of two adjacent rolls. At this time, it is possible to control the meandering of the steel sheet by changing the position of the one of the steering rolls 21, 22 in the steel plate width direction (or the slope of the rotation axis in the steel plate width direction).

And a meandering sensor 23 for measuring the meandering of the steel sheet may be installed behind the steering rolls 21, The meandering measurement sensor 23 measures the meandering of the steel sheet and transmits a signal to the meander control system 24. The meandering control system 24 transmits an operation signal to the steering rolls 21 and 22 so as to move the steel plate to the left when the steel plate is meandering to the right and to steer the steel plate to the right when the steel plate meanders to the left. And transmits an operation signal to the rolls 21 and 22.

The meander measurement sensor 23 may also be connected to the printing apparatus 100. For example, when the degree of meandering of the steel sheet exceeds the dangerous range, the printing apparatus 100 can be stopped.

The speed control devices 30 and 40 can adjust the rotational speed of the pinch rolls 31 and 41 (PR; Pinch Roll) to maintain the forward speed of the steel plate at the set speed. This is because the printing ink may drop at a desired position if the speed of the steel sheet is maintained constant. For example, the set speed of the steel sheet can be selected within the range of 30 mpm to 50 mpm. At this time, the variation of the actual traveling speed of the steel sheet can be controlled within the range of -21 μm / sec to +21 μm / sec.

The pinch rolls 31 and 41 may include two rolls disposed above and below the steel sheet. At this time, the advancing speed of the steel sheet can be adjusted by changing the rotational speed of any one or more of the pinch rolls 31, 41.

Further, the pinch rolls 31 and 41 can reduce vibration in the width direction while fixing the movement of the steel plate in the width direction. For example, the pinch rolls 31 and 41 are adjusted so that the horizontal vibration amplitude of the steel sheet is kept within the range of -11 μm to +11 μm.

In addition, the pinch rolls 31 and 41 can be installed at any one or more of the front and rear of the printing apparatus 100. The drawing shows that pinch rolls 31 and 41 are provided both in the front and rear of the printing apparatus 100. FIG. However, the pinch rolls 31 and 41 may be installed only on the rear side of the printing apparatus 100 to control the speed while pulling the steel plate, or may be provided only in front of the printing apparatus 100 to control the speed while pushing the steel plate.

The deflector rolls 51 and 52 can be used to change the direction and angle of the steel sheet. The traveling direction of the steel sheet is provided between the serpentine control device 20 and the speed control devices 30 and 40 so as to be provided between the printing device 100 and the speed control devices 30 and 40, Can change.

The dancer roll 53 is movable in a small range in the vertical direction of the steel sheet by providing the vibration reducing member between the dancer roll 53 and the base. Therefore, the dancer roll 53 can reduce the vibration of the steel sheet, and can further adjust the tension of the steel sheet. Concretely, the dancer roll 53 can reduce the vibration of the steel sheet generated by passing through the tension control device 10 and the serpentine control device 20. For example, the dancer roll 53 is adjusted such that the vertical vibration width of the steel sheet is kept within the range of -60 μm to +60 μm.

The printing apparatus 100 includes an adhesion transfer unit 120 for uniformly spreading the steel sheet in a jetting zone or a printing area A where the ink drops, And a printing unit 110 for dropping printing ink on the steel sheet.

The adhering transfer unit 120 can bring the steel plate into close contact with the conveyor belt 133 to flatten the surface of the steel plate. The flatness of the surface of the steel sheet is achieved through the tension control device 10 in the foregoing. However, the residual wave remains on the surface of the steel sheet finely. As will be described later, since the distance between the ink head 111 and the steel sheet is set in the range of 0.8 mm to 1.2 mm, when the steel sheet moving at a speed of 30 mpm to 50 mpm collides with the ink head 111, 100 may be damaged. Therefore, the remaining adhered wave is removed using the separate adherent transfer unit 120.

The position adjustment unit of the steel plate support rolls 131 and 132 adjusts the vertical position of the steel plate support rolls 131 and 132 for controlling the vertical position of the designated steel plate while supporting the steel plate, . For example, the position adjustment unit of the steel plate supporting rolls 131 and 132 can adjust the vertical position of the steel plate supporting rolls 131 and 132 so that the vertical vibration width of the steel plate is kept within -60 μm to +60 μm.

The printing unit 110 can execute printing design on the surface of the steel sheet by spraying printing ink on the steel sheet moving in the printing area A. [ This will be described in detail later.

Next, the printing unit 110 according to the embodiment of the present invention will be described with reference to FIG. 2 to FIG.

2 is a side enlarged view showing a difference in dropping point of ink according to the influence of ambient air flow.

Referring to FIG. 2, the steel sheet passes through the steel sheet at a relatively high speed to produce a constant air current around the steel sheet. Therefore, the ink falling from the nozzle 2 does not fall vertically, but moves in the direction of advance of the steel plate and falls off. However, if a uniform airflow is formed in each of the ink heads 1, the quality of the printing image is not affected. However, when a non-uniform flow occurs in any one of the ink heads 1, the printed image may be distorted.

A non-uniform flow may occur around the ink head 1. The non-uniform flow changes the drop point of the ink, causing the quality of the printed image to deteriorate. Assuming that there is one ink head 1, the outline quality of the printing image may be deteriorated by the non-uniform flow in front of the ink head 1 and on both sides of the ink head 1. However, the rear of the ink head 1 is less likely to cause uneven flow due to the influence of the air current formed by the steel plate.

In addition, when the plurality of ink heads 1 are provided in the advancing direction of the steel sheet, the ink head 1 positioned at the front most is affected by the peripheral airflow, and the drop point of the ink can be changed. The ink head 1 located relatively inward is less influenced by ambient air flow. Also, the ink head 1 positioned most rearward is also less likely to cause uneven flow due to the air current formed by the steel sheet.

FIG. 3 is a side view showing a printing unit according to a first embodiment of the present invention, and FIG. 4 is a bottom view showing a printing unit according to the first embodiment of the present invention.

3 and 4, the printing unit 110 includes an ink head 111 on which a nozzle 112 for spraying printing ink is mounted, and an ink tank 111 for discharging the ink, A curing device 113 for hardening, and an ink supply device 114 capable of continuously supplying ink without bubbles.

The ink head 111 is provided with a plurality of nozzles 112 arranged to face downward, and the plurality of nozzles 112 are arranged in parallel in the width direction of the steel sheet, but can be arranged at uniform intervals.

The ink supply device 114 may be connected to the ink head 111 and may be detachably coupled to the ink head 111 to be replaceable when the ink is insufficient.

Further, a plurality of the ink heads 111 may be arranged in parallel to the progress direction of the steel sheet. At this time, each of the ink heads 111 arranged in the direction of movement of the steel sheet may spray different colors of ink. For example, the ink heads 111 for spraying inks of C (Cyan), M (Magenta), Y (Yellow), and K (Black) colors from the front of the steel sheet in the traveling direction can be arranged side by side.

In addition, the ink head 111 for spraying ink having a single color may be arranged so that a plurality of ink heads 111 overlap each other in the width direction of the steel sheet. When the length of the ink head 111 is sufficient to cover the width of the steel sheet, one ink head 111 can take on a single color. However, since the length of the ink head 111 corresponds to the width of the steel sheet The plurality of ink heads 111 can be used by connecting them in the width direction of the steel sheet.

In the embodiment of the present invention, the two ink heads 111 are arranged side by side in the width direction of the steel sheet. At this time, the ink heads 111 may be arranged so as to overlap with each other, and the nozzles 112 may be arranged so as not to overlap. More specifically, the distance between the position of the nozzle 112 at the outermost left of the ink head 111 located on the left and the distance between the outermost right nozzle 112 of the ink head 111 located on the right side, (112). ≪ / RTI >

The curing device 113 can cure the ink using ultraviolet light (UV). The ink droplets scattered on the steel sheet can spread continuously over time. However, the larger the ink droplet size, the lower the resolution of the printed image. Therefore, the curing device 113 can harden the ink so that the ink does not reach an appropriate spread amount or more.

And the curing device 113 may be disposed behind the ink head 111. Fig. For example, the curing device 113 may be disposed behind the ink head 111 that is responsible for one color. In this case, the C ink head 111, the curing device 113, the M color ink head 111, the curing device 113, the Y color ink head 111, the curing device 113 ), A K-colored ink head 111, and a curing device 113 may be arranged side by side.

On the other hand, the distance between the steel sheet and the nozzle 112 of the ink head 111 can be adjusted in the range of 0.8 mm to 1.2 mm. If the distance between the steel plate and the nozzle 112 is longer than 1.2 mm, it becomes difficult to precisely control the position where the ink drops, thereby degrading the quality of the printing image. The ink falls on a steel plate moving at a high speed, and is affected by ambient air flow during the drop. Further, if the distance between the steel strip and the nozzle 112 is smaller than 0.8 mm, there is a possibility that the steel strip may impact the ink head 111. This is because a steel plate is not provided in a perfect plane and includes a fine wave, so a safety distance is required between the steel plate and the ink head 111. [

 The printing unit 110 according to the first embodiment of the present invention may include a base frame 115 for fixing the ink head 111 and the curing unit 113. The base frame 115 can confine the plurality of ink heads 111 and the plurality of curing apparatuses 113 to one apparatus. In one example, the base frame 115 may be disposed across a plurality of ink heads 111 and a plurality of curing apparatuses 113.

The base frame 115 can form an opening 115a for exposing the nozzle 112 of the ink head 111 and an opening 115b for exposing the irradiation portion of the curing device 113. [

The base frame 115 secures a flow development distance so that the ink droplet can drop exactly at a desired position, and a uniform flow field can be ensured in the printing area A.

To this end, the bottom surface of the base frame 115 may be located under the ink head 111. [ For example, the bottom surface of the base frame 115 may be located at the lowest position within a range that does not fall below the position of the nozzle 112.

The base frame 115 can prevent the drop point of the ink from being changed by the air current around the nozzle 112. [ That is, the base frame 115 may be provided so as to extend a predetermined distance between the front and rear sides of the nozzle 112 and both sides thereof to form a uniform flow in the printing area A. Here, the printing area A refers to a region where the nozzles 112 are located, or an area where the ink falls to form a printing image.

The lower surface 115a of the base frame 115 extending forward from the ink head 111 located at the foremost position with respect to the moving direction of the steel plate is provided with a plurality of dimples (for example, circular or elliptical grooves) dimple 200 are provided.

The number of dimples 200 and the depth T, the diameter D, the spacing S, and the like of the dimples 200 are adjusted so as to obtain a uniform flow according to the printing speed and the external flow before the printing region A Can be properly designed. This will be described later.

FIG. 5 is a side enlarged view showing a printing unit 110-1 according to a second embodiment of the present invention, and FIG. 6 is a bottom view of a dummy ink head according to a second embodiment of the present invention.

Referring to FIGS. 5 and 6, a dummy unit may be disposed in front of the ink head 111 positioned at the foremost position in the printing unit 110-1. The dummy unit is installed in front of the ink head 111 positioned most forward to provide the same condition as the ink head 111 positioned from the second position, but does not act positively. The dummy unit can ensure a uniform flow field in the print area A so that the ink droplet can drop exactly at the target position.

The dummy unit may include a dummy ink head 116 and a dummy curing unit 117. In this case, the dummy ink head 116, the dummy curing device 117, the C color ink head 111, the curing device 113, the M color ink head 111, the curing device 113, The Y color ink head 111, the curing device 113, the K color ink head 111, and the curing device 113 can be arranged side by side.

That is, the dummy ink head 116 and the dummy curing apparatus 117 are arranged so that the peripheral condition of the ink head 111 of the color C positioned at the foremost position is the same as the peripheral condition of the ink head 111 located below the second ink head 111 So that the influence of the air current on the ink head 111 can be made equal.

The dummy unit can be used when it is difficult to install the base frame 115 shown in Fig. For example, when the steel sheet in the print area A is provided with a curvature, the ink heads 111 should be arranged with the same curvature. This is because the distance between the steel plate and the ink head 111 must be constant. In this case, since it is difficult to provide the base frame 115, the dummy unit can be provided in front of the ink head 111 positioned most forward.

5 and 6, on the lower surface 116a of the dummy ink head 116 and / or the lower surface 117a of the dummy hardening device 117 facing the steel plate, a circular or elliptical A plurality of dimples 200 such as grooves are provided.

The number of dimples 200 and the depth T, the diameter D, the spacing S, and the like of the dimples 200 are adjusted so as to obtain a uniform flow according to the printing speed and the external flow before the printing region A Can be designed properly

Hereinafter, the change of the flow field by the plurality of dimples according to the embodiment of the present invention will be described. First, as shown in FIG. 7, a flow analysis range (B) for analyzing the change of the flow field in the printing region by the external flow field is set. Hereinafter, the flow analysis for a configuration having a plurality of dimples on the lower surface of the dummy ink head will be described, but it is also shown that a plurality of dimples provided in the base frame having a distance as much as the dummy ink head have the same tendency as in Fig. 3 . Here, the external flow V was tested at a different angle of 1 to 3 m / s from 10 to 45 degrees with respect to the steel sheet conveying direction in front of the dummy ink head 116.

First, in order to investigate the effect of the external flow field, the flow analysis was carried out with no flow field (V = 0). 8 shows the flow field in the printing area in the absence of an external flow field. 8, it can be seen that the flow field becomes uniform after several millimeters at the beginning of the dummy ink head 116. This uniform flow field is somewhat changed in speed between the dummy ink head 116 and the actual ink head 111, but its value is very small, so that it stabilizes immediately when it enters the printing area.

9 shows a flow field in the printing area when a flow velocity of 1 m / s is generated outside the dummy ink head 116. In Fig. As shown in FIG. 9, even if there is only an external flow of 1 m / s, the non-uniform flow in the dummy ink head 116 can not be uniformed and a strong non-uniform flow is caused just before the printing area of the actual ink head 111 .

10 is a view showing a flow field in the printing area when a flow field of 1 m / s is generated outside the dummy ink head 116 in the case where a plurality of dimples 200 are provided on the lower surface of the dummy ink head 116 according to the embodiment of the present invention Respectively. As shown in FIG. 10, the non-uniform flow field passes through the dummy ink head 116 so that the velocity is much lowered, so that the influence of the uneven flow field at the front portion of the actual ink head 111 becomes very weak. That is, it can be seen that control of the external flow field is effective by the structure having the plurality of dimples 200, and a relatively stable flow field is formed in the printing region.

 [Table 1] shows the ink jetting of the present invention depending on the presence or absence of dimples in Examples and Comparative Examples of external flow velocity (V) and external flow angle.

External flow field
Speed (m / s) External flow field
Angle (°) Example Ink bleed Comparative Example Ink bleed One 10 Apply dimple Not occurring Dimple not applied Occur 30 Not occurring Occur 45 Not occurring Slight occurrence 2 10 Not occurring Occur 30 Not occurring Occur 45 Not occurring Occur 3 10 Not occurring Occur 30 Not occurring Occur 45 Not occurring Occur

Hereinafter, description will be made of the ink droplet through various embodiments according to the depth (T), the diameter (D), the spacing (S), and the number of dimples according to the embodiment of the present invention. The diameter D of the dimples as a basic condition is 30% of the printing height H formed between the ink heads 111 and 116 and the steel sheet, the depth T and the spacing S are 50% of the dimple diameter D, , And the experiment was conducted by changing each variable.

division Dimple design variables (figures:% of print height, fixed diameter and spacing) Dimple depth Ink bleed Comparative Example 1 5% Occur Example 1 10% Not occurring Example 2 15% Not occurring Example 3 25% Not occurring Example 4 40% Not occurring Example 5 50% Not occurring Comparative Example 2 60% Occur

division Dimple design variables (values:% relative to depth, fixed depth and spacing) Dimple diameter Ink bleed Comparative Example 1 33% Occur Example 1 100% Not occurring Example 2 150% Not occurring Example 3 200% Not occurring Example 4 300% Not occurring Comparative Example 2 500% Slight occurrence

division Dimple design variables (values:% depth, depth and diameter fixed) Dimple spacing Ink bleed Example 1 50% Not occurring Example 2 100% Not occurring Example 3 200% Not occurring Example 4 300% Not occurring Example 5 400% Not occurring Example 6 500% Slight occurrence Comparative Example 1 600% Occur

The depth T of the dimple 200 is 10 to 50% of the printing height H and the diameter D of the dimple 200 is the depth of the dimple 200 as shown in Tables 2 to 4 1 to 5 times and the interval S between the dimples 200 is 0.5 to 5 times the depth T of the dimple 200, The number of the dimples 200 is changed by adjusting the interval S of the dimples 200 to the predetermined bottom length of the dimples 200. The number of the dimples 200 should be at least 20 to 50 do.

Fig. 11 is a structural diagram for explaining a close contact transfer unit according to the embodiment of the present invention.

The adhering and conveying unit 120 includes steel plate supporting rolls 131 and 132 for supporting the steel plate at the front and rear of the steel plate, a conveyor belt 133 for moving together with the steel plate while rotating, A vacuum chamber 134, and a pump 135 that provides vacuum pressure.

The steel plate support rolls 131 and 132 may be integrally provided with a conveyor support roll for supporting the conveyor belt 133. [ In this case, the conveyor belt 133 is disposed so as to surround the plurality of steel plate supporting rolls 131 and 132, and can form an endless track. And the steel plate can be supported on the conveyor belt 133 and moved together with the conveyor belt 133.

The conveyor belt 133 may be provided so as to be deformable in shape. Therefore, even if the rotational orbit is not circular, continuous rotational motion is possible. The steel plate supporting roll 131 located on the front side of the conveyor belt 133 and the steel plate supporting roll 132 located on the rear side apply tension to the conveyor belt 133 so that the conveyor belt 133 can be kept flat. However, since there is a minute wave on the steel sheet entering the close contact transfer unit 120, even if the conveyor belt 133 is kept flat, there is a possibility that a gap is formed between the contact and the conveyor belt 133.

On the other hand, it has been described that the distance between the steel strip and the ink head 111 must be constant because the distance between the steel strip and the ink head 111 is close to the front. To this end, the adherent transfer unit 120 may form a vacuum pressure on the conveyor belt 133 to bring the steel plate into contact with the conveyor belt 133.

For this, a vacuum chamber 134 may be provided in the inner space of the conveyor belt 133, and a vacuum pressure may be formed by connecting the vacuum chamber 134 to the pump 135. The conveyor belt 133 may form a plurality of vacuum holes or vacuum slits so that the vacuum pressure acts on the steel sheet. That is, the vacuum pressure formed in the vacuum chamber 134 acts on the steel sheet through the vacuum hole or the vacuum slit to adsorb the steel sheet. Therefore, the steel plate can be brought into close contact with the conveyor belt 133 and flattened.

The foregoing has shown and described specific embodiments. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined in the appended claims.

10: tension control device, 11, 12: tension breech roll,
13: tension measuring sensor, 14: tension control system,
20: Meander control device, 21, 22: Steering roll,
23: meander measurement sensor, 24: meander control system,
30, 40: speed control device, 31, 41: pinch roll,
51. 52: deflector roll, 53: dancer roll,
100: printing apparatus, 110: printing unit,
111: ink head, 112: nozzle,
113: curing device, 114: ink supply device,
115: base frame, 116: dummy ink head,
117: a dummy curing apparatus, 120: a close transfer unit,
131, 132: steel plate supporting roll, 133: conveyor belt,
134: vacuum chamber, 135: pump,
200: dimple.

Claims (9)

A printing apparatus for printing on a steel sheet surface using inkjet printing,
The printing apparatus includes:
A dummy ink head disposed on the printing region in the direction of travel of the steel sheet; and a plurality of ink heads disposed behind the dummy ink head,
Wherein a plurality of dimples are formed on a lower surface of the dummy ink head facing the steel plate. The method according to claim 1,
Further comprising a dummy curing device disposed between the dummy ink head and an ink head disposed behind the dummy ink head,
Wherein the plurality of dimples are formed on a lower surface of the dummy curing device. A printing apparatus for printing on a steel sheet surface using inkjet printing,
The printing apparatus includes:
Further comprising a base frame extending in a forward direction of the steel sheet in an ink head positioned at the frontmost side, wherein a plurality of ink heads and a plurality of curing devices are alternately arranged in the direction of travel of the steel sheet on the printing area,
And a plurality of dimples are formed on a lower surface of the base frame. 4. The method according to any one of claims 1 to 3,
Wherein a depth of the dimple is 10 to 50% of a printing height formed between the ink head and the steel plate. 4. The method according to any one of claims 1 to 3,
Wherein the diameter of the dimple is 1 to 5 times the depth of the dimple. 4. The method according to any one of claims 1 to 3,
Wherein an interval between the dimples is 0.5 to 5 times the depth of the dimple. 4. The method according to any one of claims 1 to 3,
Wherein the number of the dimples is 20 to 50. The method according to claim 1,
Further comprising: a close transfer unit for supporting the steel sheet below the printing area of the printing apparatus. The method according to claim 1,
A tension control device for applying tension to the steel plate; a skew control device for preventing skewing of the steel strip; and a speed control device for maintaining the progress speed of the steel strip.

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