JPWO2019181638A1 - Image forming device - Google Patents

Abstract

Provided is an image forming apparatus capable of suppressing slippage on a printing cylinder and suppressing deterioration of image quality. The image forming apparatus 10 is a transport unit 20 that transports the continuous paper 90 along a predetermined transport path, and a printing cylinder 40 that is provided on the transport unit 20 and around which the continuous paper 90 is wound, in the circumferential direction. A printing cylinder 40 formed by arranging grooves 60 extending along the axis in the axial direction, and a ejection portion 30 for spraying ink onto the continuous paper 90 wound around the printing cylinder 40 are provided.

Description

The present disclosure relates to an image forming apparatus.

An image forming apparatus for forming an image on continuous paper such as roll paper, and an inkjet type apparatus for spraying ink onto the continuous paper conveyed by a conveying unit is known (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-2672

When a part of the above-mentioned device is modified to provide one printing cylinder in the transport section and spray ink on the portion of continuous paper wound around the printing cylinder, the printing cylinder If the continuous paper slips (that is, slip occurs in the printing cylinder), the image quality of the formed image will be adversely affected.

An object of the present disclosure is to provide an image forming apparatus capable of suppressing slippage on a printing cylinder and suppressing deterioration of image quality.

The image forming apparatus of the first aspect is a transport unit that transports continuous paper along a predetermined transport path, and a printing cylinder that is provided in the transport unit and around which continuous paper is wound, along the circumferential direction. It is provided with a printing cylinder formed by arranging grooves extending in the axial direction, and a discharge portion for spraying ink onto continuous paper wound around the printing cylinder.

The above-mentioned "groove extending along the circumferential direction" includes a case where the direction in which the groove extends is parallel to the circumferential direction and a case where the groove is slightly inclined with respect to the circumferential direction.

In the image forming apparatus of the second aspect, when the groove width of the groove is W (mm), the groove depth is D (mm), and the groove pitch is P (mm) in the first aspect, the groove width W is It is 0.1 to 2.0 mm.

In the image forming apparatus of the third aspect, the groove width W and the groove depth D satisfy the following relationship in the second aspect.
0.05W ≤ D ≤ W

In the image forming apparatus of the fourth aspect, in the second or third aspect, the groove width W (mm), the groove depth D (mm), and the groove pitch P (mm) satisfy the following relationship.
W ≦ P ≦ WD / 0.02

The image forming apparatus of the fifth aspect has a groove width W of 0.4 to 0.6 mm and a groove depth D of 0.03 to 0.11 mm in any of the second to fourth aspects. ..

The image forming apparatus of the sixth aspect has a groove depth D of 0.03 to 0.05 mm in the fifth aspect.

The image forming apparatus of the seventh aspect has a groove pitch P of 0.4 to 0.6 mm in the fifth or sixth aspect.

In the image forming apparatus of the eighth aspect, in any one of the second to seventh aspects, the radius of curvature of the convex portion of the groove is set to the minimum value at the apex portion, and the minimum radius of curvature R1 of the convex portion of the groove is 0. It is 3 to 0.5 mm.

In the image forming apparatus of the ninth aspect, the minimum radius of curvature R2 of the recess of the groove is 0.1 to 0.5 mm in any one of the second to eighth aspects.

In any of the second to ninth aspects, the image forming apparatus of the tenth aspect has a maximum groove inclination angle θ of 65 degrees or less.

In the image forming apparatus of the eleventh aspect, in any one of the first to tenth aspects, the groove is a spiral groove.

If various dimensions change depending on the position of the groove in the extending direction, the various dimensions are considered as the average value.

According to the present disclosure, slippage on the printing cylinder can be suppressed and deterioration of image quality can be suppressed.

It is the schematic which shows the whole structure of the image forming apparatus which concerns on embodiment. It is a schematic diagram which shows the printing cylinder which concerns on embodiment. It is sectional drawing which shows the groove formed in the printing cylinder which concerns on embodiment (specifically, the sectional view which shows the state cut in the plane orthogonal to the groove extending direction). It is a figure which shows the modification of the groove formed in the printing cylinder. It is a schematic diagram which shows the modification of the printing cylinder. It is a schematic diagram which shows other modification of the printing cylinder.

Hereinafter, embodiments of the present disclosure will be described with reference to FIGS. 1 to 3.

The image forming apparatus 10 shown in FIG. 1 is an apparatus for forming an image on the surface (one side) of continuous paper 90 such as roll paper, and is specifically an inkjet printing machine. The downward direction in FIG. 1 coincides with the gravitational direction.

As the continuous paper 90 used in the image forming apparatus 10 of the present embodiment, the following continuous paper 90 is assumed.
That is, the continuous paper 90 is a high-quality paper, a medium-quality paper, a coated paper, an art paper, a coated paper, and a lightweight coated paper having a thickness of 0.05 to 0.4 mm (more specifically, 0.1 to 0.3 mm). Paper, India paper, high-quality colored paper, fancy paper, newspaper wound paper, or PET, polypropylene, nylon, polyethylene, PVC with a thickness of 0.005 to 0.25 mm (more specifically, 0.012 to 0.050 mm). A flexible packaging material or label used as a base material.

<Overall configuration of image forming device>
The image forming apparatus 10 has a transport unit 20 that transports the continuous paper 90 along a predetermined transport path. The transport unit 20 includes a plurality of rollers including a printing cylinder 40, a drying cylinder 50, and other rollers 29. The transport unit 20 transports the continuous paper 90 from the paper feed unit 21 toward the take-up unit 25 along the transport path.

The image forming apparatus 10 includes a paper feeding unit 21, a preprocessing unit 22, a printing unit 23, a drying unit 24, and a winding unit 25. The paper feeding unit 21, the preprocessing unit 22, the printing unit 23, the drying unit 24, and the winding unit 25 are arranged in this order along the transport path.

(Paper feed unit 21)
The paper feed unit 21 feeds out the continuous paper 90. The paper feed unit 21 has an unwinding roll 21A on which continuous paper 90 is wound in advance. The unwinding roll 21A is a drive roller driven by a motor or the like, and when driven, the continuous paper 90 is sent out. The paper feeding unit 21 applies a constant tension to the continuous paper 90 to feed the continuous paper 90 by rotating in a direction opposite to the feeding direction of the unwinding roll 21A or by a brake mechanism (not shown).

(Pretreatment unit 22)
The pretreatment unit 22 performs pretreatment before printing (ink spraying) on the continuous paper 90. Specifically, the pretreatment unit 22 performs a step of applying an acid precoat liquid and a step of drying the coated acid precoat liquid as an undercoat before printing on the continuous paper 90.

(Printing unit 23)
In the printing unit 23, a step of spraying ink on the continuous paper 90 is performed.

The printing unit 23 includes a printing cylinder 40 around which the continuous paper 90 is wound, and a ejection unit 30 for spraying ink on the continuous paper 90 wound around the printing cylinder 40. The ejection unit 30 has ejection heads 32Y, 32M, 32C, and 32K that eject ink droplets of each color of yellow (Y), magenta (M), cyan (C), and black (K) onto the surface of the continuous paper 90. Each of the ejection heads 32Y to 32K ejects ink droplets by a method such as a thermal method or a piezoelectric method.

The details of the printing cylinder 40 will be described later.

(Drying part 24)
In the drying unit 24, a drying step of drying the ink sprayed by the printing unit 23 is performed.

The drying unit 24 has a drying cylinder 50 around which continuous paper 90 is wound. The drying cylinder 50 is, for example, a heating roll. As the heating roll, one in which a heating heater is incorporated inside the roll is used in order to heat the surface of the roll. Further, the drying cylinder 50 may have an adsorption type roll. As the suction type roll, for example, a suction hole for sucking continuous paper is provided on the roll surface, and suction is carried out by a negative pressure generator (vacuum pump, blower, etc.) installed outside the printing machine. A paper holding the continuous paper 90 is used.

Further, the drying unit 24 may have a drying box structure in order to improve the drying efficiency. That is, the drying unit 24 may have a drying box (not shown) for accommodating the drying cylinder 50 and the like.

Further, the drying unit 24 may have a hot air device (not shown) that blows warm air onto the continuous paper 90. The hot air device includes a hot air generator, a nozzle, a suction blower for circulating hot air in the drying box, and the like.

(Winding section 25)
In the winding unit 25, the continuous paper 90 on which the image is formed is wound. The take-up unit 25 has a take-up roll 25A for winding into a roll form. The take-up roll 25A is a drive roller.

<Printing cylinder>
Next, the details of the printing cylinder 40 will be described with reference to FIGS. 2 to 4.

The diameter (diameter) of the printing cylinder 40 is, for example, 50 to 1300 mm (more specifically, 225 to 743 mm), and is about 450 mm in the present embodiment.

The material of the printing cylinder 40 is not particularly limited, but is stainless steel, carbon steel, aluminum, or the like. As the stainless steel, SUS (Steel Use Stainless) 304, SUS316, SUS313 and the like are used.

The printing cylinder 40 is surface-treated to improve hardness, corrosion resistance, and abrasion resistance. As the surface treatment, a surface treatment such as hard chrome plating, electroless nickel plating, or alumite is used.

As an example, the printing cylinder 40 of the present embodiment is made of stainless steel and has a hard chrome-plated surface treatment.

As shown in FIGS. 2 and 3, grooves 60 extending along the circumferential direction are formed side by side in the axial direction. Therefore, the air entering between the continuous paper 90 and the printing cylinder 40 can be released to the groove 60, and the holding force of the printing cylinder 40 with respect to the continuous paper 90 is improved. Therefore, slippage on the printing cylinder 40 is suppressed, and deterioration of image quality is suppressed. Further, since the printing cylinder 40 is not a suction type roll (suction roll) in which a suction hole or the like is formed on the peripheral surface 42, the manufacturing cost can be suppressed.

FIG. 2 is a schematic view showing the entire printing cylinder 40, and FIG. 3 is a cross-sectional view showing a state of being cut in a plane orthogonal to the groove extending direction. As shown in FIG. 2, the groove 60 is a spiral groove. Therefore, the direction in which the groove 60 extends is a direction slightly inclined with respect to the circumferential direction. Further, in FIG. 3, a plurality of adjacent grooves 60 are connected to each other. The groove 60 is formed by puffing after grooving. The arrows X, Y, and Z shown in FIG. 3 indicate the groove extending direction, one side in the groove width direction, and the outside in the printing cylinder radial direction, respectively.

The groove 60 is configured to include a convex portion 62B and a concave portion 62A. The convex portion 62B is a portion of the groove wall 62 of the groove 60 that is convex outward in the radial direction (upward in FIG. 3). The recess 62A is a portion of the groove wall 62 of the groove 60 that is convex inward in the radial direction (downward in FIG. 3). Specifically, as shown in FIG. 3, one groove 60 is configured to include a recess 62A located at the center of the groove 60 in the width direction and a protrusion 62B located on both sides of the recess 62A in the width direction. ing.

The radius of curvature of the convex portion 62B (the radius of curvature seen in the cross section shown in FIG. 3) is set to the minimum value at the apex portion (hereinafter referred to as “convex portion minimum radius of curvature R1”). The apex portion means a portion (the outermost portion in the radial direction) of the groove wall 62 of one groove 60, which is the farthest from the axis AX (see FIG. 2) of the printing cylinder 40.

The radius of curvature of the recess 62A is set to the minimum value at the bottom thereof. The bottom portion means the portion of the groove wall 62 closest to the axis AX of the printing cylinder 40 (the innermost portion in the radial direction).

The groove 60 has a cross section orthogonal to the groove extending direction (cross section shown in FIG. 3) and has a shape symmetrical in the groove width direction. Of course, due to manufacturing errors, the groove 60 does not have a completely symmetrical shape, but a substantially symmetrical shape.

(Dimensions of groove 60, etc.)
Various dimensions of the groove 60 of the present embodiment are set in consideration of deformation suppression of the continuous paper 90 wound around the printing cylinder 40, cleanability when ink spills on the peripheral surface 42 of the printing cylinder 40, and the like. ing.

Hereinafter, before explaining the various dimensions of the groove 60, various dimensions will be defined (see FIGS. 3 and 4).
The groove width W is the distance from one end of the groove wall 62 in the groove width direction to the other end in the groove width direction (distance in the direction perpendicular to both the groove extension direction and the printing cylinder radial direction, that is, in one groove 60. It means the distance in the left-right direction of FIG. 3, that is, the Y direction.
The groove depth D means the distance between the apex and the bottom of the groove wall 62 (distance in the printing cylinder diameter direction, that is, distance in the Z direction).
The groove pitch P is the distance between one end of the groove 60 in the groove width direction and one end of the groove width of another groove 60 adjacent to the groove 60 (direction perpendicular to both the groove extension direction and the printing cylinder diameter direction). That is, the distance in the groove width direction, that is, the distance in the Y direction).
From the above definition, the relationship of groove width W ≤ groove pitch P always holds.

The groove width W affects the deformation of the continuous paper 90 wound around the printing cylinder 40. Deformation of the continuous paper 90 adversely affects the image quality. Therefore, in the present embodiment, the groove width W is set to 0.1 to 2.0 mm. By setting the groove width W to 2.0 mm or less, deformation of the continuous paper 90 is suppressed.
From the viewpoint of suppressing deformation of the continuous paper 90, the groove width W is more preferably 0.1 to 1.0 mm, and even more preferably 0.1 to 0.6 mm.

(Ratio of groove width and groove depth)
The ratio of the groove depth D to the groove width W (D / W) affects the cleanability of the ink. On the other hand, if the groove depth D is small, it becomes difficult to secure the groove cross-sectional area, and the holding force of the printing cylinder 40 cannot be secured. The ink is cleaned, for example, by wiping the peripheral surface 42 of the printing cylinder 40.
Therefore, in this embodiment, the D / W is set to 0.05 to 1.0. When the D / W is 0.05 or more, the groove cross-sectional area is secured, and when the D / W is 1.0 or less, the cleanability is ensured.
The ratio (D / W) of the groove width W and the groove depth D is more preferably 0.05 to 0.30, preferably 0.05 to 0.20, from the viewpoint of achieving both securing the groove cross-sectional area and cleanability. More preferred.

The groove pitch P affects the number of grooves 60 arranged in the printing cylinder axis direction, and as a result, affects the groove cross-sectional area.
Therefore, in the present embodiment, the groove pitch P is set so as to satisfy the following relationship with the groove width W and the groove depth D.
W ≦ P ≦ W ^{2 /} 0.02
By setting the upper limit value of the groove pitch P, the groove cross-sectional area can be secured. The structure in which the groove pitch P is larger than the groove width W is a structure as shown in FIG. 4, and a flat portion 42A is formed between adjacent grooves 60.
Regarding the relationship between the groove width W and the groove depth D of the groove pitch P, W ≦ P ≦ WD / 0.02 is more preferable, and W ≦ P is more preferable from the viewpoint of securing the groove cross-sectional area and securing the holding force. ≦ WD / 0.03 is more preferable.

In consideration of the above points, specifically, the groove 60 of the present embodiment has a groove width W of 0.4 to 0.6 mm and a groove depth D of 0.03 to 0.11 mm. ing. Therefore, the deformation of the continuous paper 90 is suppressed, the deterioration of the image quality is suppressed, and the cleanability when the ink spills is ensured. From the viewpoint of further improving the cleanability, it is more preferable that the groove depth D is 0.03 to 0.05 mm.
In particular, in the groove 60 shown in FIG. 3, the groove pitch P is 0.4 to 0.6 mm, and the groove pitch P and the groove width W are substantially the same (P = W). That is, the flat portion 42A (see FIG. 4) is not formed between the adjacent grooves 60. Therefore, many grooves 60 can be formed when viewed in a cross section orthogonal to the groove extending direction, and a large groove cross-sectional area can be secured.

(Other dimensions, etc.)
The minimum radius of curvature of the convex portion 62B of the groove 60 (the minimum radius of curvature R1 of the convex portion) affects the deterioration of the continuous paper 90 due to the contact between the continuous paper 90 and the printing cylinder 40. This is because, in the present embodiment, the radius of curvature of the convex portion 62B is set to the minimum value at the apex portion thereof.
Therefore, in the present embodiment, the minimum radius of curvature R1 of the convex portion is set to 0.1 mm or more. Therefore, deterioration of the continuous paper 90 due to contact between the continuous paper 90 and the printing cylinder 40 is suppressed.
The minimum radius of curvature R1 of the convex portion is more preferably 0.2 mm or more, still more preferably 0.3 mm or more, from the viewpoint of suppressing deterioration of the continuous paper 90.

The minimum radius of curvature of the recess 62A of the groove 60 (minimum radius of curvature R2 of the recess) affects the cleanability when ink enters the inside of the groove 60.
Therefore, in the present embodiment, the minimum radius of curvature R2 of the recess is set to 0.1 mm or more. Therefore, it is easy to clean the ink that has entered the groove 60.
The minimum radius of curvature R2 of the recess is more preferably 0.2 mm or more, and further preferably 0.25 mm or more, from the viewpoint of ink cleanability.

In particular, in the present embodiment, the groove width W is 0.45 to 0.55 mm, the groove pitch P is 0.45 to 0.55 mm, the groove depth D is 0.035 to 0.045 mm, and the convex portion minimum radius of curvature R1. Is 0.35 to 0.45 mm, and the minimum radius of curvature R2 of the recess is 0.25 to 0.35 mm.

Further, the maximum groove inclination angle θ affects the cleanability of the ink. The maximum groove inclination angle θ is the maximum angle of the groove wall 62 with respect to the groove width direction (Y direction) when viewed in a cross section orthogonal to the groove extension direction (cross section shown in FIGS. 3 and 4).
Therefore, in the present embodiment, the maximum groove inclination angle θ is set to 65 degrees or less. Therefore, it is easy to clean (wipe off) the ink.
The maximum groove inclination angle θ is more preferably 45 degrees or less, further preferably 30 degrees or less, and further preferably 25 degrees or less from the viewpoint of ink cleanability.

[Supplemental Information]
Although the image forming apparatus according to the embodiment has been described above with reference to the drawings, the image forming apparatus is not limited to the one shown in the drawing, and the design can be appropriately changed within a range not deviating from the gist of the present disclosure. ..

For example, the groove 60 does not have to be a spiral groove, and as shown in FIGS. 5 and 6, even if the grooves (60A, 60B, 60C) adjacent to each other in the axial direction of the printing cylinder 40 are not connected to each other. It may be (the adjacent grooves may be separated from each other). As shown in FIG. 5, the direction in which the groove 60 extends may be a direction parallel to the circumferential direction. Further, the direction in which the groove 60 extends may be a direction slightly inclined with respect to the circumferential direction as shown in FIG. In any case, the groove 60 extends along the circumferential direction of the printing cylinder 40. The inclination angle with respect to the circumferential direction in which the groove 60 extends is preferably 10 degrees or less, and more preferably 5 degrees or less.

For example, the groove 60 does not have to have a shape symmetrical in the groove width direction. Further, for example, the radius of curvature of the convex portion 62B does not have to be the apex portion having the minimum value. Further, for example, the radius of curvature of the recess 62A does not have to have the minimum value at the bottom thereof.

The disclosure of Japanese patent application 2018-051710 filed on March 19, 2018 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards described herein are to the same extent as if the individual documents, patent applications, and technical standards were specifically and individually stated to be incorporated by reference. Incorporated herein by reference.

10 Image forming device 20 Conveying unit 23 Printing unit 30 Discharging unit 40 Printing cylinder 60 Groove 62 Groove wall 62A Convex part 62B Concave 90 Continuous paper AX Printing cylinder shaft W Groove width P Groove pitch D Groove depth R1 Convex part minimum radius of curvature R2 Recessed minimum radius of curvature θ Maximum groove inclination angle

Claims (11)

A transport unit that transports continuous paper along a predetermined transport path,
A printing cylinder provided on the transport portion and around which the continuous paper is wound, wherein grooves extending along the circumferential direction are formed so as to be arranged in the axial direction.
An ejection unit that sprays ink onto the continuous paper wound around the printing cylinder, and
An image forming apparatus comprising. When the groove width of the groove is W (mm), the groove depth is D (mm), and the groove pitch is P (mm),
The groove width W is 0.1 to 2.0 mm.
The image forming apparatus according to claim 1. The groove width W and the groove depth D satisfy the following relationship.
The image forming apparatus according to claim 2.
0.05W ≤ D ≤ W The groove width W (mm), the groove depth D (mm) and the groove pitch P (mm) satisfy the following relationship.
The image forming apparatus according to claim 2 or 3.
W ≦ P ≦ WD / 0.02 The groove width W is 0.4 to 0.6 mm,
The groove depth D is 0.03 to 0.11 mm.
The image forming apparatus according to any one of claims 2 to 4. The groove depth D is 0.03 to 0.05 mm.
The image forming apparatus according to claim 5. The groove pitch P is 0.4 to 0.6 mm.
The image forming apparatus according to claim 5 or 6. The radius of curvature of the convex portion of the groove is set to the minimum value at the apex portion.
The minimum radius of curvature R1 of the convex portion of the groove is 0.3 to 0.5 mm.
The image forming apparatus according to any one of claims 2 to 7. The minimum radius of curvature R2 of the recess of the groove is 0.1 to 0.5 mm.
The image forming apparatus according to any one of claims 2 to 8. The maximum groove inclination angle θ of the groove is 65 degrees or less.
The image forming apparatus according to any one of claims 2 to 9. The groove is a spiral groove,
The image forming apparatus according to any one of claims 1 to 10.