JP7430751B2 - Image forming device - Google Patents

Description

The present disclosure relates to an image forming apparatus.

2. Description of the Related Art There is known an image forming apparatus that forms an image on continuous paper such as roll paper, and an inkjet type apparatus that sprays ink onto the continuous paper conveyed by a conveyance unit (for example, Patent Document 1).

Unexamined Japanese Patent Publication No. 2016-2672

If a part of the above-mentioned device is modified to include one printing cylinder in the conveyance section and spray ink onto the part of the continuous paper that is wrapped around the printing cylinder, it is possible to If the continuous paper slips (that is, if slip occurs on the printing cylinder), the quality of the image formed will be adversely affected.

An object of the present disclosure is to provide an image forming apparatus that can suppress slip on a printing cylinder and suppress deterioration of image quality.

The image forming apparatus of the first aspect includes a conveyance section that conveys continuous paper along a predetermined conveyance path, and a printing cylinder provided in the conveyance section and around which the continuous paper is wound, and which is arranged along a circumferential direction. The printing cylinder includes a printing cylinder in which grooves extending in the axial direction are formed, and a discharge part that sprays ink onto continuous paper wound around the printing cylinder.

Note that the above-mentioned "groove extending along the circumferential direction" includes not only a direction parallel to the circumferential direction but also a direction slightly inclined with respect to the circumferential direction.

In the image forming apparatus of the second aspect, in the first aspect, 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 It is 0.1 to 2.0 mm.

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

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

In the image forming apparatus of the sixth aspect, in the fifth aspect, the groove depth D is 0.03 to 0.05 mm.

In the image forming apparatus of the seventh aspect, in the fifth or sixth aspect, the groove pitch P is 0.4 to 0.6 mm.

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 a minimum value at the apex, 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, in any one of the second to eighth aspects, the minimum radius of curvature R2 of the recessed portion of the groove is 0.1 to 0.5 mm.

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

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

In addition, when various dimensions change depending on the position in the extending direction of the groove, the various dimensions are considered as their average values.

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

1 is a schematic diagram showing the overall configuration of an image forming apparatus according to an embodiment. FIG. 1 is a schematic diagram showing a printing cylinder according to an embodiment. FIG. 2 is a cross-sectional view showing grooves formed in the printing cylinder according to the embodiment (specifically, a cross-sectional view taken along a plane perpendicular to the direction in which the grooves extend). It is a figure which shows the modification of the groove formed in a printing cylinder. FIG. 7 is a schematic diagram showing a modification of the printing cylinder. FIG. 7 is a schematic diagram showing another modification of the printing cylinder.

Embodiments of the present disclosure will be described below using FIGS. 1 to 3.

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

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

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

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

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

(Pre-processing section 22)
In the pre-processing section 22, pre-processing is performed on the continuous paper 90 before printing (ink spraying). Specifically, the pretreatment unit 22 performs a process of applying an acid precoat liquid as an undercoat before printing on the continuous paper 90, and a process of drying the applied acid precoat liquid.

(Printing Department 23)
In the printing section 23, a process of spraying ink onto the continuous paper 90 is performed.

The printing section 23 includes a printing cylinder 40 around which continuous paper 90 is wound, and a discharge section 30 that sprays ink onto the continuous paper 90 wound around the printing cylinder 40. The ejection unit 30 includes ejection heads 32Y, 32M, 32C, and 32K that eject ink droplets 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 using a thermal method, a piezoelectric method, or the like.

Note that details of the printing cylinder 40 will be described later.

(Drying section 24)
In the drying section 24, a drying process is performed to dry the ink sprayed by the printing section 23.

The drying section 24 has a drying cylinder 50 around which the 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 roll surface. Moreover, the drying cylinder 50 may be a suction type roll. For example, a suction type roll has suction holes on the roll surface to suction continuous paper, and a negative pressure generating device (vacuum pump, blower, etc.) installed outside the printing machine suctions the continuous paper while it is being conveyed. Something that holds the continuous paper 90 is used.

Additionally, the drying section 24 may have a drying box structure to improve drying efficiency. That is, the drying section 24 may include a drying box (not shown) that accommodates the drying cylinder 50 and the like.

Further, the drying section 24 may include a hot air device (not shown) that blows hot air onto the continuous paper 90. The hot air device consists of a hot air generator, a nozzle, a suction blower for circulating the hot air inside the drying box, etc.

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

<Print cylinder>
Next, details of the printing cylinder 40 will be explained using FIGS. 2 to 4.

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

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

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

The printing cylinder 40 of this embodiment is made of stainless steel, for example, and is surface-treated with hard chrome plating.

As shown in FIGS. 2 and 3, grooves 60 extending along the circumferential direction are formed in parallel in the axial direction. Therefore, air that enters between the continuous paper 90 and the printing cylinder 40 can be released into the groove 60, and the holding force of the printing cylinder 40 with respect to the continuous paper 90 is improved. Therefore, slip 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 suction holes and the like are formed in the circumferential surface 42, manufacturing costs can be suppressed.

FIG. 2 is a schematic view showing the entire printing cylinder 40, and FIG. 3 is a cross-sectional view taken along a plane perpendicular 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 slightly inclined with respect to the circumferential direction. Further, in FIG. 3, a plurality of adjacent grooves 60 are connected to each other. The grooves 60 are formed by performing a puff finish after cutting the grooves. Note that arrows X, Y, and Z shown in FIG. 3 indicate the groove extending direction, one side in the groove width direction, and the outer side in the printing cylinder radial direction, respectively.

The groove 60 includes 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 toward the outside in the radial direction (upward in FIG. 3). The recessed portion 62A is a portion of the groove wall 62 of the groove 60 that is convex radially inward (downward in FIG. 3). Specifically, as shown in FIG. 3, one groove 60 includes 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 the minimum value (hereinafter referred to as "minimum radius of curvature R1 of the convex portion") at its apex. Note that the apex portion means a portion (the most radially outer portion) of the groove wall 62 of one groove 60 from the axis AX of the printing cylinder 40 (see FIG. 2).

The radius of curvature of the recess 62A has a minimum value at its bottom. Note that the bottom portion refers to the portion of the groove wall 62 that is closest to the axis AX of the printing cylinder 40 (the portion that is closest in the radial direction).

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

(Dimensions of groove 60, etc.)
The various dimensions of the groove 60 in this embodiment are set in consideration of suppressing deformation of the continuous paper 90 wound around the printing cylinder 40 and cleaning efficiency when ink spills onto the circumferential surface 42 of the printing cylinder 40. ing.

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

The groove width W affects the deformation of the continuous paper 90 wound around the printing cylinder 40. If the continuous paper 90 is deformed, image quality will be adversely affected. Therefore, in this 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 cross-sectional area of the groove, and the holding force of the printing cylinder 40 cannot be ensured. Note that ink cleaning is performed, for example, by wiping the peripheral surface 42 of the printing cylinder 40.
Therefore, in this embodiment, D/W is set to 0.05 to 1.0. By setting D/W to 0.05 or more, the groove cross-sectional area is ensured, and by setting D/W to 1.0 or less, cleanability is ensured.
The ratio (D/W) between groove width W and groove depth D is more preferably 0.05 to 0.30, and preferably 0.05 to 0.20, from the viewpoint of ensuring both groove cross-sectional area and cleanability. More preferred.

The groove pitch P affects the number of grooves 60 arranged in the axial direction of the printing cylinder, and as a result, affects the groove cross-sectional area.
Therefore, in this 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 ensured. Note that the structure in which the groove pitch P is larger than the groove width W is a structure as shown in FIG. 4, in which a flat portion 42A is formed between adjacent grooves 60.
In addition, the relationship between the groove pitch P and the groove width W and the groove depth D is more preferably W≦P≦WD/0.02 from the viewpoint of ensuring the groove cross-sectional area and the holding force. ≦WD/0.03 is more preferable.

Taking the above points into consideration, the groove 60 of this 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, deformation of the continuous paper 90 is suppressed, thereby suppressing image quality deterioration, and cleaning performance when ink spills is ensured. Note that, from the viewpoint of further improving cleaning performance, 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 set to 0.4 to 0.6 mm, and the groove pitch P and the groove width W are approximately the same (P=W). That is, flat portions 42A (see FIG. 4) are not formed between adjacent grooves 60. Therefore, many grooves 60 can be formed in a cross section perpendicular 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 (minimum radius of curvature R1 of the convex portion) influences deterioration of the continuous paper 90 due to contact between the continuous paper 90 and the printing cylinder 40. This is because, in this embodiment, the radius of curvature of the convex portion 62B is the minimum value at its apex.
Therefore, in this 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.
In addition, from the viewpoint of suppressing deterioration of the continuous paper 90, the minimum radius of curvature R1 of the convex portion is more preferably 0.2 mm or more, and still more preferably 0.3 mm or more.

The minimum radius of curvature of the recessed portion 62A of the groove 60 (recessed portion minimum radius of curvature R2) affects the cleaning performance when ink enters the inside of the groove 60.
Therefore, in this 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.
Note that the minimum radius of curvature R2 of the recess is more preferably 0.2 mm or more, and even more preferably 0.25 mm or more, from the viewpoint of ink cleaning performance.

In particular, in this 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 minimum radius of curvature of the convex portion 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.

Furthermore, the maximum groove inclination angle θ affects the cleanability of the ink. Note that 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 perpendicular to the groove extending direction (the cross section shown in FIGS. 3 and 4).
Therefore, in this embodiment, the maximum groove inclination angle θ is set to 65 degrees or less. Therefore, cleaning (wiping off) the ink is easy.
Note that the maximum groove inclination angle θ is more preferably 45 degrees or less, even more preferably 30 degrees or less, and even more preferably 25 degrees or less from the viewpoint of ink cleaning performance.

〔supplementary explanation〕
Although the image forming apparatus according to the embodiment has been described above based on the drawings, the image forming apparatus is not limited to what is shown in the drawings, and the design can be changed as appropriate without departing 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, adjacent grooves (60A, 60B, 60C) in the axial direction of the printing cylinder 40 may not be connected to each other. (Adjacent grooves may be separated from each other). The direction in which the groove 60 extends may be parallel to the circumferential direction, as shown in FIG. Further, as shown in FIG. 6, the direction in which the groove 60 extends may be a direction slightly inclined with respect to the circumferential direction. In either case, the groove 60 extends along the circumferential direction of the printing cylinder 40. The angle of inclination of the extending direction of the groove 60 with respect to the circumferential direction is preferably 10 degrees or less, and more preferably 5 degrees or less.

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

The disclosure of Japanese Patent Application No. 2018-051710 filed on March 19, 2018 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards mentioned herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference. Incorporated herein by reference.

10 Image forming apparatus 20 Conveying section 23 Printing section 30 Discharging section 40 Print cylinder 60 Groove 62 Groove wall 62A Convex part 62B Concave part 90 Continuous paper AX Print cylinder axis W Groove width P Groove pitch D Groove depth R1 Minimum radius of curvature of convex part R2 Minimum radius of curvature of the recess θ Maximum groove inclination angle

Claims (11)

a conveyance unit that conveys continuous paper along a predetermined conveyance path;
a printing cylinder provided in the conveying section and around which the continuous paper is wound; a printing cylinder in which grooves extending along the circumferential direction are formed in rows in the axial direction;
a discharge unit that sprays ink onto a portion of the continuous paper that is wound around the printing cylinder ;
Equipped with
the printing cylinder is not a suction roll;
Image forming device. 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. Groove width W and groove depth D satisfy the following relationship,
The image forming apparatus according to claim 2.
0.05W≦D≦W Groove width W (mm), groove depth D (mm) and 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. Groove pitch P is 0.4 to 0.6 mm,
The image forming apparatus according to claim 5 or 6. The groove includes a convex portion that is a convex portion of the groove wall of the groove radially outward of the printing cylinder,
The radius of curvature of the convex portion of the groove has a minimum value at the apex,
The minimum radius of curvature R1 of the convex portion of the groove, which is the minimum radius of curvature of the convex portion, is 0.3 to 0.5 mm;
The image forming apparatus according to any one of claims 2 to 7. The groove includes a concave portion that is a convex portion of the groove wall of the groove inward in the radial direction of the printing cylinder,
The minimum radius of curvature R2 of the groove, which is the minimum radius of curvature of the recess, 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.