Spreading unit, spreading roller and digital printing equipment

Abstract

The utility model is suitable for the field of digital printing, and provides a spreading unit, a spreading roller and digital printing equipment. Each expanding unit comprises an expanding body which is of an annular structure, a plurality of bent parts are evenly distributed on the outer wall of the expanding body in the circumferential direction at intervals, the bent parts can deform in the center direction of the expanding body when stressed in the radial direction of the expanding body, and the opening directions of the bent parts are consistent. Every two adjacent bending parts of the multiple bending parts are arranged in a staggered mode in the axis direction of the expanding body so as to form two circumferential track arrangement, the two staggered bending parts have an overlapping area in the circumferential direction, and in the axis direction of the expanding body, the free ends of the bending parts located on the front same circumference extend out of the expanding body. And when being applied to the spreading roller, the anti-wrinkling device has an excellent anti-wrinkling effect, can also be suitable for spreading a thin medium which does not need to bear too large tension, and is suitable for wide medium types.

Description

Technical Field

[0001] The utility model belongs to the technical field of digital printing, and in particular relates to an expansion unit, an expansion roller and digital printing equipment. Background Art

[0002] When digital printing equipment is in operation, wrinkles are generated during the media conveyance and pattern printing process. If wrinkles are not removed, the accuracy of the printed pattern will be affected. Severe wrinkles can even scratch the printhead, potentially damaging it. Traditional wrinkle removal and stenting methods generally use brush rollers. This involves evenly spaced brush strips around the roller's circumference, extending along the roller's axis to both ends. The brush bundles on the brush strips are tilted toward one end of the roller. As the media passes through the brush roller, the soft nature of the brushes and the tilted pattern of the brush bundles cause the media to expand from one end of the roller to the other, thereby removing wrinkles. However, this structure has the following disadvantages: (1) The brush strips serve as a local wrinkle removal unit on the roller body. On the one hand, there is a blank area between the brush strips. When the medium passes through the brush roller, the area between the brush strips does not generate an expansion force on the medium, that is, a force blind area is generated; (2) A brush strip spans the entire length of the brush roller in the direction of the roller axis. The area of ​​contact between a single brush strip and the medium is too large, and the brush strip cannot ensure that each local position generates a uniform expansion force on the medium; (3) The brush strips are composed of a number of individual brush bundles arranged along the axis of the roller body. The brush bundles contain a large number of fine hairs. When the end of the brush bundle contacts the medium, the brush bundle is subjected to the pressure of the medium, and the fine hairs are easy to spread out around the brush bundle as the center, resulting in the expansion force on the current force point of the medium not being concentrated in the inclination direction of the brush strip. Therefore, the above problems will lead to poor wrinkle removal effect. Utility Model Content

[0003] The expansion unit provided by the utility model aims to solve the problem of poor wrinkle removal effect in the existing structure.

[0004] The utility model is implemented as follows: an expansion unit comprises:

[0005] The expansion body has an annular structure, and the outer wall of the expansion body is evenly spaced along its circumference. When the bending portion is subjected to force in the radial direction of the expansion body, it can be deformed toward the center of the expansion body. The openings of several of the bending portions are in the same direction. Two adjacent bending portions of several of the bending portions are staggered along the axial direction of the expansion body to form two circular trajectory arrangements. The two staggered bending portions have an overlapping area in the circumferential direction. In the axial direction of the expansion body, the free end of the bending portion located on the same circumference ahead extends out of the expansion body.

[0006] Furthermore, a first limiting portion is provided on the inner wall of the expansion body, and the first limiting portion is used for circumferential limitation when installed on the expansion roller.

[0007] Furthermore, the cross section of the expansion body passing through its axis is an isosceles trapezoid or a parallelogram.

[0008] The present invention also provides an expansion roller, comprising a roller body and the aforementioned plurality of expansion units, wherein the plurality of expansion units are sleeved on the roller body and closely arranged on the roller body along its axial direction, and the plurality of expansion units form at least one expansion group, wherein all the expansion units in each expansion group are symmetrically arranged and the openings of the curved portions face opposite directions, and the symmetry axis of the expansion group is used to correspond to the center line of the medium.

[0009] Furthermore, end covers are detachably provided at both ends of the roller body, and the periphery of the end covers protrudes from the surface of the roller body and abuts against the expansion unit of the expansion unit.

[0010] Furthermore, the expanding roller also includes a first mounting shaft and a second mounting shaft which are rotatably provided at both ends of the roller body and pass through the end cover. The first mounting shaft or the second mounting shaft can be extended and retracted relative to the roller body along its axial direction.

[0011] Furthermore, two first supporting rotating bodies are provided at intervals along the axial direction inside one end of the roller body, the first mounting shaft or the second mounting shaft is embedded in the two first supporting rotating bodies, the first mounting shaft or the second mounting shaft can rotate relative to the roller body through the first supporting rotating body, and two first limiting members are provided at intervals along the axial direction of the first mounting shaft or the second mounting shaft, the two first limiting members are distributed on opposite sides of the first supporting rotating body away from the end of the roller body, and when the first mounting shaft or the second mounting shaft is extended and retracted along the axial direction of the roller body, the first supporting rotating body may abut against one of the limiting members.

[0012] Furthermore, two second supporting rotating bodies are provided at intervals along the axial direction of the other end of the roller body, the second mounting shaft or the first mounting shaft is embedded in the two second supporting rotating bodies, and the second mounting shaft or the first mounting shaft can rotate relative to the roller body through the second supporting rotating body, and two second limiting members are provided at intervals along the axial direction of the second mounting shaft or the first mounting shaft, and the two second limiting members are distributed on opposite sides of the second supporting rotating body away from the end of the roller body and abut against the second supporting rotating body.

[0013] Furthermore, a second limiting portion is provided on the outer wall of the roller body, and the second limiting portion is used to circumferentially limit the expanding unit when the expanding unit is installed on the expanding roller.

[0014] The present utility model also provides a digital printing device, comprising a machine body, a printing platform arranged on the machine body and at least one of the aforementioned expansion rollers, at least one of the expansion rollers being rotatably arranged on one side of the output end of the printing platform, and the medium passing through the printing platform and being wound around the expansion roller before moving to a rear workstation.

[0015] The beneficial effect achieved by the present invention is that when it is applied to the expansion roller, no force blind area will be generated between two adjacent expansion units or on a single expansion unit, the medium can fully contact the expansion unit, and the curved portion, as the smallest expansion unit, can form an integral action surface when in contact with the medium, which can avoid pressure dispersion, greatly improve the expansion effect, and have an excellent wrinkle removal effect. Moreover, since pressure is applied to the curved portion by the medium to cause the curved portion to deform and thus achieve the expansion effect, the curved portion only needs a small pressure to deform, so the present structure can also be used for expansion of thinner thickness media that do not need to bear too much tension, and is adaptable to a wide range of media types. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a structural diagram of the expansion unit provided by the utility model;

[0017] Figure 2 yes Figure 1 Cross-section at AA;

[0018] Figure 3 This is a schematic structural diagram of a bending portion of an expansion unit provided by the present invention;

[0019] Figure 4 This is a structural comparison diagram of the bending portion of an expansion unit provided by the utility model before and after being subjected to force;

[0020] Figure 5 This is a structural schematic diagram of an embodiment of an expansion roller provided by the utility model;

[0021] Figure 6 This is a schematic structural diagram of an expansion roller provided by the utility model, in which all the curved parts on the expansion units are arranged on the same circumference and then arranged on the roller body;

[0022] Figure 7 yes Figure 5 Cross-section at the middle BB;

[0023] Figure 8is another embodiment of the structure schematic diagram of the expanding roller body provided by the utility model.

[0024] Figure 9 is Figure 5 the cross section view at C-C in the middle;

[0025] Figure 10 is the structure schematic diagram of the digital printing equipment provided by the utility model.

[0026] Explanation of reference numerals:

[0027] 1, expanding body; 11, first limiting part; 2, bending part; 2a, free end; 10, expanding unit; 10a, expanding group; 20, roller body; 201, second limiting part; 30, end cover; 40, first supporting rotary body; 50, second supporting rotary body; 60, first mounting shaft; 70, second mounting shaft; 80, first limiting piece; 90, second limiting piece; 100, fixed shaft sleeve; 200, machine body; 300, printing platform; 400, expanding roller; 500, medium. Specific implementation

[0028] In order to make the utility model's purpose, technical scheme and advantage more clearly clear, the following is combined with the drawing and example, and the utility model is further detailedly explained.It should be understood that the specific example described here is only used to explain the utility model, and is not used to limit the utility model.

[0029] See Figures 1-4The embodiment of the present invention provides an expansion unit 10, including an expansion body 1, which has an annular structure. The expansion body 1 with an annular structure can facilitate the installation of the expansion unit 10 on the roller body of the expansion roller described below, thereby realizing the modular and rapid assembly of the expansion roller. The outer wall of the expansion body 1 is evenly spaced along its circumference on a number of curved portions 2. When the curved portion 2 is subjected to force in the radial direction of the expansion body 1, it can be deformed toward the center of the expansion body 1. When the medium passes through the expansion unit 10, the contact between the medium and the curved portion 2 will apply a force toward the center of the expansion body 1 to the curved portion 2. After being subjected to pressure, the curved portion 2 will be deformed, thereby causing the opening of the curved portion 2 to shrink close to the expansion body 1. Therefore, when the wrinkles of the medium pass through the surface of the curved portion 2, the wrinkles will spread toward the opening of the curved portion 2, thereby achieving To achieve the effect of wrinkle removal, the openings of several curved portions 2 are oriented in the same direction, so that it is convenient to assemble multiple expansion units 10 into the following roller body according to actual needs to achieve the required wrinkle removal amplitude. Two adjacent curved portions 2 of several curved portions 2 are staggered along the axial direction of the expansion body 1 to form two circular track arrangements. The two staggered curved portions 2 have an overlapping area in the circumferential direction. In the axial direction of the expansion body 1, the free end 2a of the curved portion 2 located on the same circumference in front extends out of the expansion body 1. In this way, when the expansion unit 10 is assembled on the following expansion roller, no continuous gap is generated on the same circumference between the adjacent two expansion units 10, and they can fully contact with the medium, so that no force blind area is generated, the force is more uniform, and the best wrinkle removal effect can be achieved (see Figure 5 When the plurality of curved portions 2 are arranged on the same circumference, when the widening unit 10 is assembled on the roller body of the widening roller, the curved portions 2 are not arranged in the axial direction, and a continuous gap h is generated between two adjacent curved portions 2 in the circumferential direction, resulting in the widening unit 10 not being in full contact with the medium, thereby affecting the wrinkle removal effect (see Figure 6 ).

[0030] The expansion unit 10 provided by the present invention, when applied to the expansion roller, will not produce a force blind area between two adjacent expansion units 10 or on a single expansion unit 10, the medium can fully contact the expansion unit 10, and the curved portion 2, as the smallest expansion unit 10, can form an integral action surface when in contact with the medium, which can avoid pressure dispersion, greatly improve the expansion effect, and have an excellent wrinkle removal effect. Moreover, since pressure is applied to the curved portion 2 by the medium to cause the curved portion 2 to deform and thus achieve the expansion effect, the curved portion 2 only needs a small pressure to deform, so this structure can also be used for expansion of thinner thickness media that do not need to bear too much tension, and is adaptable to a wide range of media types.

[0031] Specifically, the expansion body 1 and the bending part 2 are both made of deformable materials, including but not limited to plastic, and the bending part 2 and the expansion body 1 are integrally molded, which facilitates the production and processing of the expansion unit 10 and improves the structural stability of the expansion body 1 and the bending part 2.

[0032] See also Figure 1 Furthermore, a first limiting portion 11 is provided on the inner wall of the expansion body 1. The first limiting portion 11 is used for circumferential limitation when installed on the expansion roller, that is, it can be used to cooperate with the second limiting portion 201 described below, so that the expansion body 1 can be positioned in the axial direction of the expansion roller, and the expansion unit 10 can be driven to rotate synchronously when the expansion roller rotates.

[0033] Furthermore, the cross section of the expansion body 1 passing through its axis is an isosceles trapezoid or a parallelogram. Thus, when several expansion bodies 1 are mounted on the roller body described below, there is no gap between two adjacent expansion units 10 and the sides can engage with each other, which facilitates installation and improves the compactness and stability of the structure.

[0034] See also Figure 2 Furthermore, the cross-section of the expansion body 1 of this embodiment can be preferably designed as a parallelogram. Compared with the structure using an isosceles trapezoid, which requires the production of positive and inverted isosceles trapezoids separately during production, the parallelogram does not need to be distinguished and only needs to produce one type, which can facilitate the mass production of the expansion unit 10.

[0035] See also Figure 5 、 Figure 7 、 Figure 8 The embodiment of the present invention further provides an expansion roller 400, comprising a roller body 20 and the aforementioned plurality of expansion units 10, wherein the plurality of expansion units 10 are sleeved on the roller body 20 and closely arranged along the axial direction of the roller body 20 to cover the roller body 20, and the plurality of expansion units 10 form at least one group of expansion groups 10a, and all the expansion units 10 of each expansion group 10a are symmetrically arranged and the openings of the curved portions 2 face opposite to each other, and the symmetry axis of the expansion unit 10 group corresponds to the center line of the medium. In this way, when the medium passes through the roller surface of the roller body 20, the medium can be expanded from the middle to both ends to remove wrinkles. Compared with the prior art in which the brush strips are tilted in one direction as a whole to remove wrinkles from one end to the other end of the medium, the present design structure can reduce the distance of wrinkle removal in the same direction, reduce the possibility of wrinkle superposition generated during the wrinkle removal process, and improve the wrinkle removal effect.

[0036] By adopting a structure in which the roller body 20 and the expansion unit 10 are assembled separately, compared with the integrated structure of the expansion roller 400 in the prior art, it can be easily disassembled and reassembled. The position of the symmetry line of the expansion unit 10 on the roller body 20 can be adjusted according to the center line position of the medium so that the symmetry line can be aligned with the center line of the medium, thereby reducing the positional deviation between the center line of the medium and the symmetry lines of several expansion units 10, and thus the medium can be more evenly expanded toward both ends along the symmetry plane, achieving the best wrinkle removal effect. In addition, a corresponding number of expansion groups 10a can be set according to the current amount of media to adapt to different production needs.

[0037] For example, see Figure 5 、 Figure 7 When the number of media is 1, the plurality of expanding units 10 on the roller body 20 are symmetrically arranged with the center line of the roller body 20 perpendicular to the axial direction as the symmetry axis to form a group of expanding units 10a. The openings of the curved portions 2 of all the expanding units 10 on each side of the symmetry axis face the same direction, and the openings of the curved portions 2 of the expanding units 10 on both sides of the symmetry axis are arranged opposite to each other. When the media passes over the expanding roller 400, the center line of the media is aligned with the symmetry axis. When the media passes over the expanding unit 10, the media can expand from the center to both ends, thereby achieving wrinkle removal; see Figure 8 When the number of media is two, the several expanding units 10 on the roller body 20 are divided into two expanding groups 10a. Each expanding group 10a is located on both sides of the roller body 20. Two media pass over the roller body 20 at the same time. The center line of the media corresponds to the symmetry axis of each expanding group 10a. When the media passes over the expanding unit 10, each media can expand from the center to both ends, thereby achieving synchronous expansion of the two media.

[0038] It should be noted that the number of expansion groups 10a set on the roller body 20 can be assembled using a corresponding number of expansion units 10 according to the actual number of media, and is not limited to 1 group or 2 groups listed in this example. The length of each expansion group 10a is adapted to the width of the medium, so that it can be used more flexibly and can adapt to different production needs.

[0039] See also Figure 7 Furthermore, end caps 30 are detachably provided at both ends of the roller body 20. The periphery of the end caps 30 protrudes from the surface of the roller body 20 and abuts against the widening unit 10. By disassembling the end caps 30, the assembly of the widening unit 10 on the roller body 20 can be facilitated.

[0040] See also Figure 7Further, the inner part of the two ends of the roller body 20 is respectively provided with a fixed shaft sleeve 100, and the end cover 30 is connected and fixed with the fixed shaft sleeve 100. The fixed shaft sleeve 100 is arranged on the end cover 30 to increase the connecting space of the end cover 30 and the roller body 20, so that the hollow structure of the roller body 20 is realized and the thickness of the roller body 20 is reduced, thereby reducing the weight of the roller body 20 to facilitate the installation of the expanding roller 400 and reduce the material cost.

[0041] Referring to Figure 5 , Figure 7 Further, the expanding roller 400 further comprises a first mounting shaft 60 and a second mounting shaft 70 which are respectively rotatably arranged at the two ends of the roller body 20 and pass through the end cover 30, and the first mounting shaft 60 or the second mounting shaft 70 can be telescoped along the axial direction of the roller body 20. Through the first mounting shaft 60 and the second mounting shaft 70, the installation of the expanding roller 400 can be realized. By arranging one of the mounting shafts to be telescopic, the length of the roller body 20 in the axial direction can be effectively adjusted, and the installation of the roller body 20 is more convenient, that is, after the mounting shaft with the telescopic function is retracted by a certain stroke, the mounting shaft is installed with other fixed parts, which can avoid the installation interference caused by the close proximity of the mounting shaft and the mounting part, thereby improving the installation difficulty, and also can adapt to the installation of different length spaces.

[0042] Referring to Figure 7 Further, the inner part of one end of the roller body 20 is spaced apart along the axial direction and provided with two first support rotating bodies 40, the first mounting shaft 60 or the second mounting shaft 70 is embedded in the two first support rotating bodies 40, and the first mounting shaft 60 or the second mounting shaft 70 can be rotated relative to the roller body 20 through the first support rotating body 40 to enable the medium to drive the roller body 20 to rotate relative to the first mounting shaft 60 or the second mounting shaft 70. By arranging the two first support rotating shafts to install the first mounting shaft 60 or the second mounting shaft 70, the stability of the installation of the first mounting shaft 60 or the second mounting shaft 70 on the roller body 20 can be ensured, and the phenomenon of shaking of the first mounting shaft 60 or the second mounting shaft 70 relative to the axis in the axial direction can be avoided. Two first limiting pieces 80 are arranged on the first mounting shaft 60 or the second mounting shaft 70 along the axial direction and are distributed on the opposite sides of the first support rotating body 40 away from the end part of the roller body 20. When the first mounting shaft 60 or the second mounting shaft 70 is telescoped along the axial direction of the roller body 20, the first support rotating body 40 can abut against one of the limiting pieces, and the first limiting piece 80 can limit the first mounting shaft 60 or the second mounting shaft 70 in the axial direction. The distance between the two first limiting pieces 80 also provides the first mounting shaft 60 or the second mounting shaft 70 with the telescopic space in the axial direction.

[0043] Referring to Figure 7Furthermore, two second supporting rotating bodies 50 are spaced apart inside the other end of the roller body 20 along its axial direction, and the second mounting shaft 70 or the first mounting shaft 60 is embedded in the two second supporting rotating bodies 50. The second mounting shaft 70 or the first mounting shaft 60 can be rotated relative to the roller body 20 through the second supporting rotating body 50 so that the medium can drive the roller body 20 to rotate relative to the second mounting shaft 70 or the first mounting shaft 60. Setting two second supporting rotating shafts to install the second mounting shaft 70 or the first mounting shaft 60 can ensure that the second mounting shaft 70 or the first mounting shaft 60 0 or the first mounting shaft 60 is installed on the roller body 20 to ensure stability, and to avoid shaking of the second mounting shaft 70 or the first mounting shaft 60 relative to its axis in the axial direction, two second limiting members 90 are provided on the second mounting shaft 70 or the first mounting shaft 60 at intervals along the axial direction thereof, and the two second limiting members 90 are distributed on opposite sides of the second supporting rotating body 50 away from the end of the roller body 20 and abut against the second supporting rotating body 50, so that the second mounting shaft 70 or the first mounting shaft 60 can be fixedly connected to the roller body 20 in the axial direction.

[0044] See also Figure 7 Specifically, the first supporting rotating body 40 and the second supporting rotating body 50 are respectively nested and matched with the corresponding fixed sleeves 100 on the roller body 20. The first supporting rotating body 40 and the second supporting rotating body 50 can be selected from but not limited to bearings, and the first limiting member 80 and the second limiting member 90 can be selected from but not limited to retaining springs.

[0045] See also Figure 9 Furthermore, a second limiting portion 201 is provided on the outer wall of the roller body 20. The second limiting portion 201 is used to circumferentially limit the expanding unit 10 when the expanding unit 10 is installed on the expanding roller, that is, the second limiting portion 201 can cooperate with the first limiting portion 11 on the expanding body 1, so that the expanding body 1 can be conveniently limited in the circumferential direction of the roller body 20.

[0046] See also Figure 10 The embodiment of the present invention further provides a digital printing device, including a body 200, a printing platform 300 arranged on the body 200, and at least one of the aforementioned expansion rollers. One of the at least one expansion roller is rotatably arranged on the output end side of the printing platform 300. The medium 500 passes through the printing platform 300 and is wound around the expansion roller before moving to the next workstation.

[0047] The digital printing equipment provided by the present invention has an excellent expansion and wrinkle removal effect. It can be used to expand thinner media 500 that do not need to bear too much tension, and is adaptable to a wide range of media 500 types. The expansion roller 400 can be easily disassembled and reassembled, and the position of the symmetry line of the expansion unit 10 on the roller body 20 can be adjusted according to the center line position of the medium 500 so that the symmetry line can be aligned with the center line of the medium 500, thereby reducing the position deviation between the center line of the medium 500 and the symmetry lines of several expansion units 10, and thus the medium 500 can be expanded more evenly toward both ends along the symmetry plane, achieving the best wrinkle removal effect. In addition, a corresponding number of expansion groups 10a can be set according to the current number of media 500 to adapt to different production needs.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An expansion unit, characterized in that: include: The expansion body has an annular structure, and the outer wall of the expansion body is evenly spaced along its circumference. When the bending portion is subjected to force in the radial direction of the expansion body, it can be deformed toward the center of the expansion body. The openings of several of the bending portions are in the same direction. Two adjacent bending portions of several of the bending portions are staggered along the axial direction of the expansion body to form two circular trajectory arrangements. The two staggered bending portions have an overlapping area in the circumferential direction. In the axial direction of the expansion body, the free end of the bending portion located on the same circumference ahead extends out of the expansion body.

2. The expansion unit according to claim 1, wherein: The inner wall of the expansion body is provided with a first limiting portion, and the first limiting portion is used for circumferential limiting when installed on the expansion roller.

3. The expansion unit according to claim 1, wherein: The cross section of the expansion body passing through its axis is an isosceles trapezoid or a parallelogram.

4. An expansion roller, characterized in that: It comprises a roller body and a plurality of expansion units as described in any one of claims 1 to 3, wherein the plurality of expansion units are sleeved on the roller body and closely arranged on the roller body along the axial direction thereof, and the plurality of expansion units form at least one expansion group, and all the expansion units in each expansion group are symmetrically arranged and the openings of the curved parts face opposite directions, and the symmetry axis of the expansion group is used to correspond to the center line of the medium.

5. The expanding roller according to claim 4, wherein: End caps are detachably provided at both ends of the roller body. The periphery of the end caps protrudes from the surface of the roller body and abuts against the expansion unit of the expansion unit.

6. The expanding roller according to claim 5, characterized in that: The expanding roller further includes a first mounting shaft and a second mounting shaft rotatably disposed at both ends of the roller body and passing through the end cover. The first mounting shaft or the second mounting shaft can be extended and retracted relative to the roller body along its axial direction.

7. The expanding roller according to claim 6, characterized in that Two first supporting rotating bodies are provided inside one end of the roller body along the axial direction thereof, and the first mounting shaft or the second mounting shaft is embedded in the two first supporting rotating bodies. The first mounting shaft or the second mounting shaft can rotate relative to the roller body through the first supporting rotating body, and two first limiting members are provided on the first mounting shaft or the second mounting shaft along the axial direction thereof. The two first limiting members are distributed on opposite sides of the first supporting rotating body away from the end of the roller body. When the first mounting shaft or the second mounting shaft is extended and retracted along the axial direction of the roller body, the first supporting rotating body can abut against one of the limiting members.

8. The expanding roller according to claim 6, wherein: Two second supporting rotating bodies are provided inside the other end of the roller body along its axial direction, and the second mounting shaft or the first mounting shaft is embedded in the two second supporting rotating bodies. The second mounting shaft or the first mounting shaft can rotate relative to the roller body through the second supporting rotating body, and two second limiting members are provided on the second mounting shaft or the first mounting shaft along its axial direction. The two second limiting members are distributed on opposite sides of the second supporting rotating body away from the end of the roller body and abut against the second supporting rotating body.

9. The expanding roller according to claim 4, wherein: A second limiting portion is provided on the outer wall of the roller body, and the second limiting portion is used to circumferentially limit the expanding unit when the expanding unit is installed on the expanding roller.

10. A digital printing device, characterized in that: The machine comprises a body, a printing platform arranged on the body, and at least one expanding roller as described in any one of claims 4 to 9, wherein at least one of the expanding rollers is rotatably arranged on one side of the output end of the printing platform, and the medium passes through the printing platform and is wound around the expanding roller and then moves to the next workstation.

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