Friction shaft for slitter

Abstract

The present invention relates to a friction shaft for a slitter having a winding pipe installed on the outer surface thereof for winding a unit material formed by cutting a raw material such as various types of paper, fabric, or film at predetermined intervals into a roll shape, wherein a rotary shaft thereof includes: a first body forming a body; a plurality of main flow paths that penetrate the first body in a longitudinal direction and have different lengths; and a plurality of sub flow paths that connect the plurality of main flow paths and the outside of the first body.

Description

Technical Field

[0001] The present disclosure relates to a friction shaft and, more particularly, to a friction shaft for a slitter, the friction shaft having a winding pipe installed on an outer surface thereof for winding a unit material formed by cutting a raw material such as various types of papers, fabrics, or films at predetermined intervals, in a roll shape.Background Art

[0002] A slitter is a device that cuts a raw material, such as fabric, paper, or synthetic resin film, in a longitudinal direction while unwinding a roll of raw material.

[0003] The raw material is wound and fed into a roll, which is cut by the slitter into a number of unit materials of small widths.

[0004] When using the slitter, the unit materials should be separately wound onto an outer surface of a corresponding winding pipe. However, it is difficult to wind all the unit materials at a uniform torque with a single rotary shaft.

[0005] When all the unit materials are wound onto the single rotary shaft, the unit materials wound on the winding pipe will be wound inconsistently, so some parts are loosely wound and some parts are too tightly wound.

[0006] Therefore, the former case has the problem that the roll may be unwound during the supply or use process, and the latter case has the problem that the unit material is broken or stretched.

[0007] When an expensive film is stretched, it loses its market value, resulting in significant financial losses.

[0008] Therefore, a winding device is provided to wind the unit material with uniform torque for all unit materials.

[0009] A shaft component used significantly in the winding device is referred to as a friction shaft, also known as an air friction shaft, because it typically utilizes pneumatics.

[0010] In this regard, Korean Patent Publication Application No. 10-2014-0083406 (July 04, 2014) proposed a friction shaft for a slitter including: a rod winding shaft rotating by a winding motor; a first hole formed in the winding shaft by perforating it in a longitudinal direction of the winding shaft; a plurality of third holes formed by perforating the winding shaft to penetrate from an outer circumferential surface of the winding shaft to the first hole and spaced from each other at intervals in an extension direction of the first hole; a plurality of holders inserted into an inner circumference of a paper tube to wind a unit material and having a form of short tubes fitted over an outer circumference of the winding shaft sequentially, and installed at each of positions where the third holes are provided; and a first pneumatic generator supplying compressed air to the first hole to allow the holders to pressurize the paper tube. Each of the holders includes: a plurality of lug seating grooves formed into a short tube along an outer circumference; a holder base having connection holes perforated to connect the third holes and the lug seating grooves; lugs inserted into the lug seating grooves to be movable in a radial direction of the winding shaft; a spring having a first end supported by each lug and a second end supported by each lug seating groove to allow each lug to ensure a force of elastically protruding in the radial direction of the winding shaft; a fixation cover pressing an outer edge of each lug to prevent the lug from being separated from each lug seating groove, and fixed to the holder base; and a pneumatic guide means guiding compressed air supplied to the first hole to compress each lug toward a center portion of the winding shaft.

[0011] Air pressure generated from an air compressor of the friction shaft may be introduced from a pneumatic generator coupled to an end of the winding shaft into the winding shaft.

[0012] Then, the air pressure from the end of the winding shaft causes the plurality of lugs arranged in the longitudinal direction of the winding shaft to protrude from the outer circumferential surface of the winding shaft.

[0013] On the other hand, the conventional friction shaft receives air from the end of the winding shaft.

[0014] In this case, even when the same pressure of air is supplied to each of the holders from the winding shaft, there is a problem that torque variation occurs in each of the holders due to various factors including assembly tolerance, surface roughness, heat generated by the operation of the product, wear and tear, stuck foreign objects in the retainers, bearings, etc. that make up the friction shaft.

[0015] As a result, there is a problem that a unit material wound on the winding pipe is wound unevenly.

[0016] Therefore, some parts are wound loosely, while others are wound too tightly, causing an unwinding problem during the supply or use process in the former case, and a breakage or stretch problem of the unit material in the latter case.

[0017] For the above reasons, the field has been developed to find a way to ensure that the unit material wound on the winding pipe is wound consistently, but so far, satisfactory results have not been obtained.Disclosure Technical Problem

[0018] Accordingly, the present disclosure has been made keeping in mind the above problems occurring in the related art, and an objective of the present disclosure is to provide a friction shaft for a slitter that is capable of winding a unit material wound onto a winding pipe evenly.

[0019] The above and other objects, features, and advantages of the present disclosure and a method of achieving them will be more clearly understood with reference to the embodiments described below in detail in conjunction with the accompanying drawings.Technical Solution

[0020] In order to achieve the above-described objective, according to an embodiment of the present disclosure, there is provided a friction shaft for a slitter that has a winding pipe installed on an outer surface thereof for winding a unit material formed by cutting a raw material such as various types of paper, fabric, or film at predetermined intervals, into a roll shape, and the friction shaft for a slitter includes: a rotary shaft rotating by a driving motor and receiving compressed air from an air supply part; a plurality of friction cores shaped into a short pipe and mounted to the rotary shaft side by side; a plurality of lug parts mounted to the friction cores and spaced from each other in a shaft direction of the rotary shaft at equal intervals; and a rotary joint coupled to an end of the rotary shaft and supplying air from the air supply part to the rotary shaft, wherein the rotary shaft may include: a first body forming a body; a plurality of main flow paths penetrating the first body in a longitudinal direction and having different lengths; and a plurality of sub flow paths connecting the plurality of main flow paths and an outside space of the first body.

[0021] Each of the friction cores may include: a second body forming a body; a through hole penetrating the second body in a radial direction and into which each lug part is inserted; a plurality of seating holes formed at locations in the second body where the seating holes do not overlap with the through holes, and spaced from each other in a circumferential direction of the rotary shaft at equal intervals; and a plurality of rollers seated in the seating holes.

[0022] Each of the friction cores may further include: a retainer support mounted to the rotary shaft side by side; and a retainer supported by the retainer support and generating torque through air pressure from the outside space.

[0023] The plurality of friction cores may include: four first cores disposed in a first region that is an end where the rotary joint is coupled; four second cores disposed in a second region that is adjacent to the first region in an opposite directional region to the location where the rotary joint is coupled based on the first region; four third cores disposed in a third region that is adjacent to the second region in the opposite directional region to the location where the rotary joint is coupled based on the second region; and four fourth cores disposed in a fourth region that is adjacent to the third region in the opposite directional region to the location where the rotary joint is coupled based on the third region.

[0024] The plurality of friction cores may be successively mounted to the first body.

[0025] The main flow paths may include: a first main flow path that penetrates from one end to which the rotary joint is coupled, to a first region; a second main flow path that does not overlap with the first main flow path and penetrates from the end to which the rotary joint is coupled, to a second region; a third main flow path that does not overlap with the first main flow path and the second main flow path and penetrates from the end to which the rotary joint is coupled, to a third region; and a fourth main flow path that does not overlap with the first main flow path to the third main flow path and penetrates from the end to which the rotary joint is coupled, to a fourth region.

[0026] The sub flow paths may include: a first sub flow path formed on the first main flow path in the first region; a second sub flow path formed on the second main flow path in the second region; a third sub flow path formed on the third main flow path in the third region; and a fourth sub flow path formed on the fourth main flow path in the fourth region.

[0027] The rotary shaft may further include: a plurality of grooves formed on an outer circumferential surface of the first body in the longitudinal direction and connected to the sub flow paths.

[0028] The grooves may be respectively formed on the first sub flow path, the second sub flow path, the third sub flow path, and the fourth sub flow path.

[0029] Each of the lug parts may include: an upper lug chucking the winding pipe with an upper surface thereof brought into contact with an inner circumferential surface of the winding pipe when compressed air is introduced from the air supply part; a connection part extending downwards from a lower surface of the upper lug; a lower lug having a seating part on an upper surface thereof and extending from a lower end of the connection part to both ends in the circumferential direction of the rotary shaft; and an elastic member having a first end seated on the seating part and a second end brought into contact with an inner circumferential surface of the second body.

[0030] The elastic member may be a compression spring.

[0031] The rotary joint may include: a third body forming a body; a first connection hole penetrating a first end and a second end of the third body and connected to the first main flow path; a second connection hole penetrating a first end and a second end of the third body and connected to the second main flow path; a third connection hole penetrating a first end and a second end of the third body and connected to the third main flow path; and a fourth connection hole penetrating a first end and a second end of the third body and connected to the fourth main flow path.Advantageous Effects

[0032] According to the present disclosure, the plurality of main flow paths is respectively connected to the plurality of friction cores provided in various regions, and different types of air pressures flow into the plurality of friction cores respectively, so that the torques generated by the air pressures are respectively applied to the plurality of friction cores, thereby reducing the torque variation of the plurality of friction cores.Description of Drawings

[0033] FIG. 1 is a perspective view showing a friction shaft for a slitter according to the embodiment of the present disclosure. FIG. 2 is a sectional view showing the friction shaft for a slitter according to the embodiment of the present disclosure. FIG. 3 is a sectional view showing the friction shaft for a slitter according to another embodiment of the present disclosure. FIG. 4 is a perspective view showing a rotary shaft and a rotary joint of the friction shaft for a slitter according to the embodiment of the present disclosure. FIG. 5 is a sectional view cut along line A-A' shown in FIG. 4. FIG. 6 is a sectional view cut along line B-B' shown in FIG. 4. FIG. 7 is a perspective view showing a lug part of the friction shaft for a slitter according to the embodiment of the present disclosure. FIG. 8 is an enlarged view showing part A shown in FIG. 2. FIGS. 9A and 9B are views showing operation of the friction shaft for a slitter according to the embodiment of the present disclosure. FIG. 10 is a perspective view showing a rotary shaft according to another embodiment of the present disclosure. FIG. 11 is a sectional view cut along line C-C' shown in FIG. 10. FIG. 12 is a sectional view cut along line D-D' shown in FIG. 10. Mode for Invention

[0034] Embodiments of the present disclosure are presented to make complete disclosure of the present disclosure and help those who are ordinarily skilled in the art best understand the present disclosure. Various changes to the following embodiments are possible, and the scope of the present disclosure is not limited to the following embodiments. However, the embodiments are provided to make the disclosure more faithful and complete and to fully convey the ideas of the present disclosure to those skilled in the art. Also, in the following drawings, each configuration is exaggerated for illustrative purposes and clarity, and the same reference numerals are used throughout the different drawings to designate the same or similar components. The expression "and / or" is interpreted to include each of enumerated items, and all combinations including one or more items selected from among the enumerated items.

[0035] Terms used in this specification are selected to describe embodiments and thus should not be construed as the limit of the present invention.

[0036] An element expressed in a singular form in this specification may be plural elements unless it is necessarily singular in the context. The terms "comprise" and / or "comprising" means inclusion of a shape, number, process, operations, member, element, and / or a group of those, but do not mean exclusion of or denial of addition of another shape, number, process, operation, element, and / or a group of those.

[0037] Below, an exemplary embodiment of the present disclosure is described in detail with reference to the accompanying drawings.

[0038] FIG. 1 is a perspective view showing a friction shaft for a slitter according to the embodiment of the present disclosure. FIG. 2 is a sectional view showing the friction shaft for a slitter according to the embodiment of the present disclosure. FIG. 3 is a sectional view showing the friction shaft for a slitter according to another embodiment of the present disclosure. FIG. 4 is a perspective view showing a rotary shaft and a rotary joint of the friction shaft for a slitter according to the embodiment of the present disclosure. FIG. 5 is a sectional view cut along line A-A' shown in FIG. 4. FIG. 6 is a sectional view cut along line B-B' shown in FIG. 4. FIG. 7 is a perspective view showing a lug part of the friction shaft for a slitter according to the embodiment of the present disclosure. FIG. 8 is an enlarged view showing part A shown in FIG. 2. FIGS. 9A and 9B are views showing operation of the friction shaft for a slitter according to the embodiment of the present disclosure. FIG. 10 is a perspective view showing a rotary shaft according to another embodiment of the present disclosure. FIG. 11 is a sectional view cut along line C-C' shown in FIG. 10. FIG. 12 is a sectional view cut along line D-D' shown in FIG. 10.

[0039] Referring to FIGS. 1 to 12, according to the embodiment of the present disclosure, a friction shaft having a winding pipe, which is installed on an outer surface thereof for winding a unit material into a roll shape that is formed by cutting a raw material such as various types of paper, fabric, or film at predetermined intervals, includes a rotary shaft 100, friction cores 200 mounted to the rotary shaft 100, lug parts 300 mounted to the friction cores 200 and chucking the winding pipe selectively, and a rotary joint 400 coupled to one end of the rotary shaft 100.

[0040] Meanwhile, the winding pipe may be made of a paper tube, a fiber reinforced plastic (FRP) core, or the like.

[0041] The rotary shaft 100 rotates by a driving motor and receives compressed air from the air supply part 500.

[0042] This rotary shaft 100 includes a first body 110, main flow paths 120, and sub flow paths 130.

[0043] The first body 110 forms a body of the rotary shaft 100.

[0044] The main flow paths 120 penetrate the first body 110 in a longitudinal direction and include a plurality of main flow paths 120 having different lengths.

[0045] Furthermore, the compressed air supplied selectively from the air supply part 500 flows through the main flow paths 120.

[0046] The sub flow paths 130 include a plurality of sub flow paths 130 to correspond to the plurality of main flow paths 120 and connect the main flow paths and the outside space of the first body 110.

[0047] In other words, the sub flow paths 130 supply the compressed air supplied from the air supply part 500 to the friction cores 200.

[0048] The friction cores 200 are shaped into a short pipe, and a plurality of friction cores 200 is mounted to the rotary shaft 100 in the longitudinal direction side by side at predetermined intervals.

[0049] Furthermore, the winding pipe is mounted to the outer circumferential surfaces of the friction cores 200.

[0050] Each of the friction cores 200 includes a second body 210, through holes 220, seating holes 230, rollers 240, retainer supports 250, and retainers 260.

[0051] The second body 210 forms a body of each friction core 200 and is shaped into a short pipe.

[0052] The through holes 220 includes a plurality of through holes 220 and are spaced from each other in a circumferential direction of the second body 210 at equal intervals.

[0053] Furthermore, the through holes 220 penetrate the second body 210 in a radial direction, and the lug parts 300 are inserted into the through holes 220.

[0054] The through holes 220 connect the inside space and the outside space of each friction core 200.

[0055] Furthermore, each through hole 220 is shaped in a T-shape having a section with a wide upper portion and a narrow lower portion.

[0056] The seating holes 230 include a plurality of seating holes 230, and the plurality of seating holes 230 is formed on the second body 210 in the longitudinal direction of the rotary shaft 100 and spaced from each other at equal intervals in the circumferential direction of the second body 210.

[0057] The seating holes 230 are formed in a region of the second body 210 where the seating holes do not overlap with the plurality of through holes 220, i.e., between one through hole and another through hole of the plurality of through holes 220.

[0058] The rollers 240 include a plurality of rollers 240 to correspond to the seating holes 230, and the plurality of rollers 240 is seated into the plurality of seating holes 230 respectively.

[0059] Furthermore, an inner circumferential surface of the winding pipe is brought into contact with the outermost portions of the rollers 240.

[0060] In other words, the rollers 240 enable the winding pipe to be easily transferred from the friction cores 200 when the lug parts 300 do not perform chucking the winding pipe.

[0061] Accordingly, when the position of the winding pipe is adjusted on the friction cores 200 without the winding pipe chucked by the lug parts 300, the rollers 240 rotate with the winding pipe and easily move the heavy winding pipe to adjust the position thereof.

[0062] The retainer supports 250 are preferably shaped into a ring and include a pair of retainer supports 250 arranged at a first end and a second end of the second body 210.

[0063] Furthermore, an outer circumferential surface of each retainer support 250 is brought into contact with an inner circumferential surface of the second body 210, and an inner circumferential surface thereof is brought into contact with each retainer 260.

[0064] The retainers 260 include a pair of retainers 260, and the pair of retainers 260 is arranged on the inner circumferential surface of each retainer support 250 in leftward and rightward directions of the lug parts 300.

[0065] An outer circumferential surface of each retainer 260 is brought into contact with the inner circumferential surface of each retainer support 250, and an inner circumferential surface thereof is brought into contact with an outer circumferential surface of the first body 110.

[0066] The retainers 260 are made of an elastic material such as silicone or urethane and have grooves in facing directions.

[0067] Accordingly, when air pressure is injected from the outside space, the grooves of the retainers 260 are elastically deformed due to the pressure of air, and the outer circumferential surfaces of the retainers 260 pressurize the inner circumferential surfaces of the retainer supports 250, then the inner circumferential surfaces of the retainers 260 pressurize the outer circumferential surface of the first body 110.

[0068] This structure may allow the retainers 260 to efficiently transmit torques to the friction cores 200 when the rotary shaft 100 rotates.

[0069] Meanwhile, the plurality of friction cores 200 having the above-described configuration may include first cores 200_1, second cores 200_2, third cores 200_3, and fourth cores 200_4.

[0070] As shown in FIG. 2, the first cores 200_1 indicate four friction cores 200 of the plurality of friction cores 200 disposed in a first region A1 that is one end to which the rotary joint 400 is coupled, and the second cores 200_2 indicate another four friction cores 200 of the plurality of friction cores 200 disposed in a second region A2 that is adjacent to the first region A1 in an opposite direction to the location with the rotary joint 400 based on the first region A1.

[0071] Furthermore, the third cores 200_3 indicate another four friction cores 200 of the plurality of friction cores 200 disposed in a third region A3 that is adjacent to the second region A2 in the opposite direction to the location with the rotary joint 400 based on the second region A2, and the fourth cores 200_4 indicate another four friction cores 200 of the plurality of friction cores 200 disposed in a fourth region A4 that is adjacent to the third region A3 in the opposite direction to the location with the rotary joint 400 based on the third region A3.

[0072] Meanwhile, the present disclosure is described as the friction shaft for a slitter of the present disclosure is divided into the first region A1 to the fourth region A4 for convenience of description, but as shown in FIG. 3, the friction shaft for a slitter of the present disclosure may be divided into at least two regions according to an usage environment of the present disclosure, in other words, into the first region A1 to an nth region An. Accordingly, the friction cores 200 may include the first cores 200_1 and the second cores 200_2 or the first cores 200_1 to an nth core 200_n so that the friction cores correspond to the regions.

[0073] The multiple friction cores 200, i.e., the first cores 200_1, the second cores 200_2, the third cores 200_3, and the fourth cores 200_4 are sequentially fitted over the first body 110 in the shaft direction.

[0074] Accordingly, the lug parts 300 inserted into the through holes 220 of the second body 210 are brought into contact with different locations on the inner circumferential surface of the winding pipe, allowing the winding pipe to be stably chucked.

[0075] Meanwhile, the main flow paths 120 having different lengths include a first main flow path 121, a second main flow path 122, a third main flow path 123, and a fourth main flow path 124.

[0076] The first main flow path 121 penetrates the first body 110 from one end to which the rotary joint 400 is coupled, to the first region A1, and the second main flow path 122 penetrates the first body 110 from the end to which the rotary joint 400 is coupled, to the second region A2 without overlapping with the first main flow path 121.

[0077] Furthermore, the third main flow path 123 penetrates the first body 110 from the end to which the rotary joint 400 is coupled, to the third region A3 without overlapping with the first main flow path 121 and the second main flow path 122, and the fourth main flow path 124 penetrates the first body 110 from the end to which the rotary joint 400 is coupled, to the fourth region A4 without overlapping with the first main flow path 121 to the third main flow path 123.

[0078] Furthermore, the sub flow paths 130 formed on end portions of the main flow paths 120 include a first sub flow path 131, a second sub flow path 132, a third sub flow path 133, and a fourth sub flow path 134 according to formed location in the first main flow path 121 to the fourth main flow path 124.

[0079] The first sub flow path 131 is formed on the first main flow path 121 penetrating to the first region A1 in the first region A1, and the second sub flow path 132 is formed on the second main flow path 122 penetrating to the second region A2 in the second region A2.

[0080] Furthermore, the third sub flow path 133 is formed on the third main flow path 123 formed to the third region A3 in the third region A3, and the fourth sub flow path 134 is formed on the fourth main flow path 124 formed to the fourth region A4 in the fourth region A4.

[0081] The multiple sub flow paths 130 is formed at positions corresponding to the multiple friction cores 200.

[0082] In other words, the friction shaft of the present disclosure may supply compressed air having different pressures through the main flow paths 120 and the sub flow paths 130.

[0083] Therefore, through the multiple main flow paths 120 and the multiple sub flow paths 130, the compressed air having different pressures is supplied to the friction cores 200 respectively, and torque generated by air pressure are applied to the multiple friction cores 200.

[0084] In other words, this can reduce torque variance caused by various factors, including assembly tolerances, surface roughness, heat generated by the operation of the product, wear and tear, and stuck foreign objects.

[0085] Therefore, it is possible to stably wind a raw material to be wound around the winding pipe by generating constant torque to each friction core with the winding pipe mounted.

[0086] Meanwhile, according to the present disclosure, the torque variation applied to the friction cores 200 including a plurality of friction cores is reduced as the compressed air having a different pressure is supplied to each of the first cores 200_1 to the fourth cores 200_4, or the compressed air is supplied only to a desired region among the first cores 200_1 to the fourth cores 200_4, so the friction shaft of the present disclosure can have the versatility according to the usage environment.

[0087] The plurality of lug parts 300 is provided for chucking the winding pipe, on the friction cores 200, and spaced from each other at equal intervals in a circumferential direction of the rotary shaft 100, and is mounted to the friction cores 200 to be slidingly movable in the radial direction.

[0088] Specifically, the plurality of lug parts 300 is inserted into the plurality of through holes 220 that are formed in the circumferential direction of the second body 210.

[0089] In other words, the lug parts 300 are inserted into the through holes 220 penetrating the outer circumferential surface and the inner circumferential surface of the second body 210, thereby being slidingly movable depending on the compressed air supplied from the sub flow paths 130.

[0090] The lug parts 300 include an upper lug 310, a connection part 320, a lower lug 330, and an elastic member 340.

[0091] The upper lug 310 has an upper surface exposed outwards, and when the compressed air is introduced from the air supply part 500, the upper surface of the upper lug is brought into contact with the inner circumferential surface of the winding pipe.

[0092] In other words, the upper lug 310 chucks the winding pipe when the compressed air is introduced.

[0093] The connection part 320 extends downwards from an upper surface of the upper lug 310, and has a width narrower than a longitudinal width of the rotary shaft 100.

[0094] The lower lug 330 extends from a lower end of the connection part 320 toward both circumferential ends of the rotary shaft 100, and a seating part 331 is formed at each upper surface based on the connection part 320.

[0095] In other words, the lower lug 330 is covered by the second body 210.

[0096] Accordingly, it is possible to efficiently prevent the lower lug 330 from separating from the through holes when being pressed by the sub flow paths 130, thereby preventing it from escaping to the outside.

[0097] Preferably, the elastic member 340 is made of a compression spring and seated on the seating part 331 of the lug parts 300.

[0098] Furthermore, the elastic member 340 allows the lug parts 300 to be returned toward the rotary shaft 100 when the supply of air pressure to the sub flow paths 130 stops.

[0099] To this end, a first end of the elastic member 340 is seated on the seating part 331 and a second end of the elastic member 340 is brought into contact with the inner circumferential surface of the second body 210.

[0100] Therefore, the elastic member 340 elastically supports the lower lug 330, so when supply of air pressure to the sub flow paths 130 stops, the elastic member 340 allows the lug parts 300 to be elastically returned toward the rotary shaft 100.

[0101] The rotary joint 400 is coupled to one of opposite ends of the rotary shaft 100, and supplies air from the air supply part 500 to the main flow path of the rotary shaft 100.

[0102] The rotary joint 400 includes a third body 410, a first connection hole 420, a second connection hole 430, a third connection hole 440, and a fourth connection hole 450.

[0103] The third body 410 may for the body of the rotary joint 400.

[0104] The first connection hole 420 penetrates a first end and a second end of the third body 410 and is connected to the first main flow path 121. The second connection hole 430 penetrates a first end and a second end of a region that does not overlap with the first connection hole 420, and is connected to the second main flow path 122.

[0105] Furthermore, the third connection hole 440 penetrates a first end and a second end of a region that does not overlap with the first connection hole 420 and the second connection hole 430 in the third body 410 and is connected to the third main flow path 123. The fourth connection hole 450 penetrates a first end and a second end of a region that does not overlap with the first connection hole 420 to the third connection hole 440 in the third body 410 and is connected to the fourth main flow path 124.

[0106] Connection tubes are connected to the first connection hole 420 to the fourth connection hole 450 so that connection tubes a compressed air can be supplied from.

[0107] Accordingly, each of the first connection hole 420 to the fourth connection hole 450 may be supplied with compressed air at different pressures from the air supply part 500 as necessary.

[0108] Therefore, the first connection hole 420 to the fourth connection hole 450 supply the compressed air at different pressures to the plurality of main flow paths 120 and the plurality of sub flow paths 130, which can efficiently reduce the torque variation applied to each of the first cores 200_1 to the fourth cores 200_4 of the first region A1 to the fourth region A4.

[0109] For example, when the torque of the second cores 200_2 among the first cores 200_1 to the fourth cores 200_4 is low, relatively greater air pressure is selectively supplied to the second cores 200_2 than the other cores 200_1, 200_3, and 200_4, thereby causing a relatively greater torque to the retainers 260 of the second cores 200_2. When the torque of the fourth cores 200_4 among the first cores 200_1 to the fourth cores 200_4 is high, relatively smaller air pressure is selectively supplied to the fourth cores 200_4 than the other cores 200_1, 200_2, and 200_3, thereby causing a relatively smaller torque to the retainers 260 of the fourth cores 200_4.

[0110] Accordingly, the torque variation of the first cores 200_1 to the fourth cores 200_4 arranged in the first region A1 to the fourth region A4 can be reduced.

[0111] Meanwhile, according to another embodiment of the present disclosure, the rotary shaft 100 may include grooves 140.

[0112] The plurality of grooves 140 is formed in the longitudinal direction of the rotary shaft 100 on the outer circumferential surface of the first body 110, and is connected to the plurality of sub flow paths 130, respectively.

[0113] Specifically, the grooves 140 are formed at the first sub flow path 131, the second sub flow path 132, the third sub flow path 133, and the fourth sub flow path 134, respectively.

[0114] Accordingly, the grooves 140, for example, may supply compressed air at uniform pressure to the lug parts 300 inserted into the four friction cores 200, which constitute the first cores 200_1.

[0115] As described above, the embodiments disclosed herein should be considered from an illustrative perspective and not a limiting perspective. The scope of the present disclosure is presented in the claims, not in the above-described description, and any differences within the scope of the claims have to be construed as included in the present disclosure.

Claims

1. A friction shaft for a slitter having a winding pipe installed on an outer surface for winding a unit material formed by cutting a raw material such as various types of paper, fabric, or film at a predetermined interval, into a roll shape, the friction shaft comprising: a rotary shaft rotating by a driving motor and receiving compressed air from an air supply part; a plurality of friction cores shaped into a short pipe and mounted to the rotary shaft side by side; a plurality of lug parts mounted to the friction cores and spaced from each other in a shaft direction of the rotary shaft at equal intervals; and a rotary joint coupled to an end of the rotary shaft and supplying air from the air supply part to the rotary shaft, wherein the rotary shaft comprises: a first body forming a body; a plurality of main flow paths penetrating the first body in a longitudinal direction and having different lengths; and a plurality of sub flow paths connecting the plurality of main flow paths and an outside space of the first body.

2. The friction shaft of claim 1, wherein each of the friction cores comprises: a second body forming a body; a through hole penetrating the second body in a radial direction and into which each lug part is inserted; a plurality of seating holes formed at locations in the second body where the seating holes do not overlap with the through holes, and spaced from each other in a circumferential direction of the rotary shaft at equal intervals; and a plurality of rollers seated in the seating holes.

3. The friction shaft of claim 2, wherein each of the friction cores further comprises: a retainer support mounted to the rotary shaft side by side; and a retainer supported by the retainer support and generating torque through air pressure from the outside space.

4. The friction shaft of claim 3, wherein the plurality of friction cores comprises: four first cores disposed in a first region that is an end where the rotary joint is coupled; four second cores disposed in a second region that is adjacent to the first region in an opposite directional region to the location where the rotary joint is coupled based on the first region; four third cores disposed in a third region that is adjacent to the second region in the opposite directional region to the location where the rotary joint is coupled based on the second region; and four fourth cores disposed in a fourth region that is adjacent to the third region in the opposite directional region to the location where the rotary joint is coupled based on the third region.

5. The friction shaft of claim 3, wherein the plurality of friction cores is successively mounted to the first body.

6. The friction shaft of claim 5, wherein the main flow paths comprise: a first main flow path that penetrates from one end to which the rotary joint is coupled, to a first region; a second main flow path that does not overlap with the first main flow path, and penetrates from the end to which the rotary joint is coupled, to a second region; a third main flow path that does not overlap with the first main flow path and the second main flow path, and penetrates from the end to which the rotary joint is coupled, to a third region; and a fourth main flow path that does not overlap with the first main flow path to the third main flow path and penetrates from the end to which the rotary joint is coupled, to a fourth region.

7. The friction shaft of claim 6, wherein the sub flow paths comprise: a first sub flow path formed on the first main flow path in the first region; a second sub flow path formed on the second main flow path in the second region; a third sub flow path formed on the third main flow path in the third region; and a fourth sub flow path formed on the fourth main flow path in the fourth region.

8. The friction shaft of claim 7, wherein the rotary shaft further comprises: a plurality of grooves formed on an outer circumferential surface of the first body in the longitudinal direction and connected to the sub flow paths.

9. The friction shaft of claim 8, wherein the grooves are respectively formed on the first sub flow path, the second sub flow path, the third sub flow path, and the fourth sub flow path.

10. The friction shaft of claim 3, wherein each of the lug parts comprises: an upper lug chucking the winding pipe with an upper surface thereof brought into contact with an inner circumferential surface of the winding pipe when compressed air is introduced from the air supply part; a connection part extending downwards from a lower surface of the upper lug; a lower lug having a seating part on an upper surface thereof and extending from a lower end of the connection part to both ends in the circumferential direction of the rotary shaft; and an elastic member having a first end seated on the seating part and a second end brought into contact with an inner circumferential surface of the second body.

11. The friction shaft of claim 10, wherein the elastic member is a compression spring.

12. The friction shaft of claim 6, wherein the rotary joint comprises: a third body forming a body; a first connection hole penetrating a first end and a second end of the third body and connected to the first main flow path; a second connection hole penetrating a first end and a second end of the third body and connected to the second main flow path; a third connection hole penetrating a first end and a second end of the third body and connected to the third main flow path; and a fourth connection hole penetrating a first end and a second end of the third body and connected to the fourth main flow path.

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