Spreading unit, spreading roller and digital printing equipment

Abstract

The invention 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 invention 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 working, wrinkles will be generated during the transportation of the media and the printing process of the pattern. If the wrinkles are not removed, the accuracy of the printed pattern will be affected. Severe wrinkles will also scratch the nozzle and may cause damage to the nozzle. The traditional wrinkle removal and stenting method generally uses a brush roller, that is, brush strips are evenly spaced on the circumference of the roller body, and the brush strips extend along the axis of the roller body to both ends of the roller body. The brush bundles on the brush strips are tilted toward one end of the roller body. When the medium passes through the brush roller, due to the soft characteristics of the brush and the tilted texture of the brush bundle, the medium will be expanded from one end of the roller body to the other end to achieve wrinkle removal. However, this structure has the following disadvantages: (1) The brush strip is used 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 will be generated; (2) A brush strip spans the entire length of the brush roller in the direction of the roller axis. The contact area 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 strip is composed of a number of single brush bundles arranged along the axis of the roller body. The brush bundle contains a large number of fine hairs. When the end of the brush bundle contacts the medium, when the brush bundle is subjected to the pressure of the medium, the fine hairs are also easy to spread around with 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. Summary of the invention

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

[0004] The present invention is implemented as follows: an expansion unit comprises:

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

[0006] Furthermore, a first limiting portion is provided on the inner wall of the expanding body, and the first limiting portion is used for circumferential limiting when installed on the expanding 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 several expansion units, wherein the several expansion units are sleeved on the roller body and closely arranged on the roller body along its axial direction, and the several 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.

[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 disposed at both ends of the roller body and pass through the end cover, and 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 arranged 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 be rotated relative to the roller body through the first supporting rotating body, two first limiting members are arranged 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 or retracted along the axial direction of the roller body, the second supporting rotating body can abut against one of the limiting members.

[0012] Furthermore, two second supporting rotating bodies are provided at intervals inside the other end of the roller body along its axial direction, 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 at intervals along the axial direction on the second mounting shaft or the first mounting shaft, 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 invention 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 be in full contact with 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 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 It is a structural schematic diagram of the expansion unit provided by the present invention;

[0017] Figure 2 yes Figure 1 Cross-sectional view at AA in the middle;

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

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

[0020] Figure 5 It is a structural schematic diagram of an implementation mode of an expansion roller provided by the present invention;

[0021] Figure 6 It is a schematic structural diagram of an expansion unit of an expansion roller provided by the present invention, in which all the curved parts 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 8 It is a structural schematic diagram of another embodiment of an expansion roller body provided by the present invention;

[0024] Fig. 9 yes Figure 5 Cross-section at CC;

[0025] Fig.10 It is a structural schematic diagram of a digital printing device provided by the present invention.

[0026] Description of Figure Numbers:

[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 rotating body; 50. Second supporting rotating body; 60. First mounting shaft; 70. Second mounting shaft; 80. First limiting member; 90. Second limiting member; 100. Fixed sleeve; 200. Machine body; 300. Printing platform; 400. Expanding roller; 500. Medium. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0029] See also Figure 1-Figure 4The embodiment of the present invention provides an expansion unit 10, including an expansion body 1, which is an annular structure. The expansion body 1 with an annular structure can facilitate the expansion unit 10 to be installed on the roller body of the expansion roller described below, so as to realize the modular rapid assembly of the expansion roller. The outer wall of the expansion body 1 is evenly spaced along its circumference on a plurality of curved parts 2. When the curved part 2 is subjected to force in the radial direction of the expansion body 1, it can be deformed toward the center direction of the expansion body 1. When the medium passes through the expansion unit 10, the contact between the medium and the curved part 2 will exert a force toward the center direction of the expansion body 1 on the curved part 2. The curved part 2 will be deformed after being subjected to pressure, thereby causing the opening of the curved part 2 to shrink in the direction close to the expansion body 1. Therefore, when the wrinkles of the medium pass through the surface of the curved part 2, the wrinkles will spread toward the opening of the curved part 2, thereby achieving The opening directions of the plurality of curved portions 2 are consistent, so that it is convenient to assemble a plurality of widening units 10 to the roller body described below according to actual needs to achieve the required wrinkle removal range. Two adjacent curved portions 2 of the plurality of curved portions 2 are staggered along the axial direction of the widening body 1 to form two circumferential track arrangements. The two staggered curved portions 2 have an overlapping area in the circumferential direction. In the axial direction of the widening body 1, the free end 2a of the curved portion 2 located on the same circumference in front extends out of the widening body 1. In this way, when the widening unit 10 is assembled on the widening roller described below, no continuous gap is generated on the same circumference between the two adjacent widening units 10, and the widening units 10 can be fully in 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 that the widening unit 10 will not be in full contact with the medium, thereby affecting the wrinkle removal effect (see Figure 6 ).

[0030] When the expansion unit 10 provided by the present invention is applied to the expansion roller, no force blind area will be generated between two adjacent expansion units 10 or on a single expansion unit 10, and the medium can be in full contact with the expansion unit 10. The bending 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 bending portion 2 through the medium to cause the bending portion 2 to deform and achieve the expansion effect, the bending portion 2 only needs a small pressure to deform. Therefore, 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.

[0031] Specifically, the expansion body 1 and the bending portion 2 are both made of deformable materials, including but not limited to plastic, and the bending portion 2 and the expansion body 1 are integrally formed, which can facilitate the production and processing of the expansion unit 10 and improve the structural stability of the expansion body 1 and the bending portion 2.

[0032] See also Figure 1 Furthermore, a first limiting portion 11 is provided on the inner wall of the widening body 1, and the first limiting portion 11 is used for circumferential limiting when installed on the widening roller, that is, it can be used to cooperate with the second limiting portion 201 described below, so that the widening body 1 can be positioned in the axial direction of the widening roller, and the widening unit 10 can be driven to rotate synchronously when the widening 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 a plurality of expansion bodies 1 are installed on the roller body described below, there is no gap between two adjacent expansion units 10 and the sides can still 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 the present embodiment can be preferably designed as a parallelogram. Compared with the isosceles trapezoid structure, which requires the production of positive and inverted isosceles trapezoids separately during production, the parallelogram does not need to be distinguished and only one needs to be produced, 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 expanding roller 400, comprising a roller body 20 and the aforementioned plurality of expanding units 10, wherein the plurality of expanding units 10 are sleeved on the roller body 20 and closely arranged along the axial direction thereof to cover the roller body 20, wherein the plurality of expanding units 10 form at least one group of expanding groups 10a, wherein all the expanding units 10 of each group of expanding groups 10a are symmetrically arranged and the openings of the curved portions 2 face opposite to each other, and the symmetry axis of the group of expanding units 10 corresponds to the center line of the medium, so that 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 widening unit 10 are assembled separately, compared with the integrated structure of the widening roller 400 in the prior art, it is easy to disassemble and reassemble, and the position of the symmetry line of the widening 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 position deviation of the center line of the medium and the symmetry lines of several widening units 10, thereby allowing the medium to be more evenly expanded to both ends along the symmetry plane to achieve the best wrinkle removal effect. In addition, a corresponding number of widening groups 10a can be set according to the current number of media to meet different production needs.

[0037] For example, see Figure 5 , Figure 7 When the number of media is 1, a plurality of widening 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 widening group 10a. The openings of the curved portions 2 of all widening units 10 on each side of the symmetry axis face the same direction, and the openings of the curved portions 2 of the widening units 10 on both sides of the symmetry axis are arranged opposite to each other. When the media passes over the widening roller 400, the center line of the media corresponds to the symmetry axis. When the media passes under pressure on the widening unit 10, the media can be widened from the center to both ends, thereby achieving wrinkle removal; see Figure 8 When the number of media is 2, the plurality of 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, and two media pass through 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 under pressure on the expanding unit 10, each medium can expand from the center to both ends, thereby realizing synchronous expansion of the two media.

[0038] It should be noted that the number of expansion groups 10a provided 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 as cited 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 Further, the two ends of the roller body 20 are detachably provided with end caps 30, and the periphery of the end caps 30 protrudes from the surface of the roller body 20 and abuts against the widening unit 10 of 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 7Furthermore, fixed sleeves 100 are fixedly disposed inside both ends of the roller body 20, and the end caps 30 are connected and fixed to the fixed sleeves 100. The fixed sleeves 100 are connected to the end caps 30 to increase the connection space between the end caps 30 and the roller body 20, so that the roller body 20 can adopt a hollow structure and reduce the thickness of the roller body 20, thereby reducing the weight of the roller body 20 to facilitate the installation of the widening roller 400 and reduce material costs.

[0041] See also Figure 5 , Figure 7 Further, the widening roller 400 further includes a first mounting shaft 60 and a second mounting shaft 70 which are rotatably disposed at both ends of the roller body 20 and pass through the end cover 30, respectively. The first mounting shaft 60 or the second mounting shaft 70 can be retracted relative to the roller body 20 along the axial direction thereof. The widening roller 400 can be installed by means of the first mounting shaft 60 and the second mounting shaft 70. The length of the roller body 20 in the axial direction can be effectively adjusted by setting one of the mounting shafts to be retractable, which makes it easier to install the roller body 20. That is, during installation, the mounting shaft with a retractable function can be retracted to a certain stroke before the mounting shaft and other fixed components are installed, which can avoid the installation shaft and the installation component being extremely close to each other, resulting in differential installation interference, thereby increasing the difficulty of installation, and can also adapt to the installation of spaces of different lengths.

[0042] See also Figure 7 Furthermore, two first supporting rotating bodies 40 are spaced apart inside one end of the roller body 20 along its axial direction, and the first mounting shaft 60 or the second mounting shaft 70 is embedded in the two first supporting rotating bodies 40. The first mounting shaft 60 or the second mounting shaft 70 can rotate relative to the roller body 20 through the first supporting rotating body 40 so that the medium can drive the roller body 20 to rotate relative to the first mounting shaft 60 or the second mounting shaft 70. The two first supporting rotating shafts are provided to mount the first mounting shaft 60 or the second mounting shaft 70, which can ensure the stability of the installation of the first mounting shaft 60 or the second mounting shaft 70 on the roller body 20 and avoid the first mounting shaft 60 or the second mounting shaft 70 on the shaft. In order to produce a shaking phenomenon upward relative to its axis, two first limit members 80 are arranged on the first mounting shaft 60 or the second mounting shaft 70 along its axis direction at intervals, and the two first limit members 80 are distributed on the opposite sides of the first supporting rotating body 40 away from the end of the roller body 20. When the first mounting shaft 60 or the second mounting shaft 70 is extended or retracted along the axis direction of the roller body 20, the second supporting rotating body 50 can abut against one of the limit members, and the first limit member 80 can realize the limitation of the first mounting shaft 60 or the second mounting shaft 70 in the axis direction, and the distance between the two first limit members 80 also provides an axial expansion and contraction space for the first mounting shaft 60 or the second mounting shaft 70.

[0043] See also Figure 7Furthermore, two second supporting rotating bodies 50 are spaced apart inside the other end of the roller body 20 along the axial direction thereof, 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. The two second supporting rotating shafts are provided to mount the second mounting shaft 70 or the first mounting shaft 60, which can ensure that 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. In order to improve the stability of the installation of the second mounting shaft 70 or the first mounting shaft 60 on the roller body 20 and avoid the second mounting shaft 70 or the first mounting shaft 60 from shaking 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 the 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 use but are not limited to bearings, and the first limiting member 80 and the second limiting member 90 can use but are not limited to retaining springs.

[0045] See also Fig. 9 Furthermore, a second limiting portion 201 is provided on the outer wall of the roller body 20, and 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 easily limited in the circumferential direction of the roller body 20.

[0046] See also Fig.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 widening rollers, one of the at least one widening roller is rotatably arranged on one side of the output end of the printing platform 300, and the medium 500 passes through the printing platform 300 and is wound around the widening roller and then moves to the next station.

[0047] The digital printing equipment provided by the present invention has an excellent effect of expanding and removing wrinkles, and can be used to expand thinner thickness media 500 that do not need to bear too much tension, and is adaptable to a wide range of media 500 types; the expanding roller 400 can be easily disassembled and reorganized, and the position of the symmetry line of the expanding 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 of the center line of the medium 500 and the symmetry lines of several expanding units 10, and then the medium 500 can be more evenly expanded to both ends along the symmetry plane, thereby achieving the best wrinkle removal effect. In addition, a corresponding number of expanding groups 10a can be set according to the current number of media 500, so as 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 substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

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

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

5. The expansion roller according to claim 4, characterized in that: End caps are detachably provided at both ends of the roller body, and 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 expansion roller according to claim 5, characterized in that: The expansion roller further comprises a first mounting shaft and a second mounting shaft which are rotatably arranged at both ends of the roller body and pass through the end cover respectively. 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 expansion roller according to claim 6, characterized in that: Two first supporting rotating bodies are arranged 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, two first limiting members are arranged at intervals along the axial direction of the first mounting shaft or the second mounting shaft, the two first limiting members are distributed on the 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 or retracted along the axial direction of the roller body, the second supporting rotating body can abut against one of the limiting members.

8. The expansion roller according to claim 6, characterized in that: Two second supporting rotating bodies are arranged at intervals inside the other end of the roller body along the axial direction thereof, 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 arranged at intervals along the axial direction thereof on the second mounting shaft or the first mounting shaft, 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 expansion roller according to claim 4, characterized in that: A second limiting portion is disposed on the outer wall of the roller body, and the second limiting portion is used to circumferentially limit the expansion unit when the expansion unit is installed on the expansion roller.

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

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